Biomedical subjects

J H Judkins

Publications and source records attributed to J H Judkins.

9 recordsLinked to original sources

PubMed1996

Intraoperative ketorolac and posttonsillectomy bleeding.

OBJECTIVE: To determine the occurrence of posttonsillectomy bleeding in patients who received intraoperative ketorolac tromethamine. DESIGN: Retrospective analysis. SETTING: Academic tertiary care center. PATIENTS: Three hundred eleven patients who underwent tonsillectomy in an 18-month period. MAIN OUTCOME MEASURE: Occurrence of bleeding complications in patients who received ketorolac during tonsillectomy. RESULTS: Fifty-eight of 311 patients who underwent tonsillectomy received intraoperative ketorolac with an overall postoperative bleeding rate of 17%. This high rate of bleeding complications compares with 4.4% in the remaining 253 patients who received traditional opioid analgesics. CONCLUSIONS: Until further controlled studies have been conducted, the use of ketorolac in patients undergoing tonsillectomy should be avoided because of the increased incidence of postoperative bleeding complications.

Adolescent↗

PubMed1993

The development of age-related deficits in several presynaptic processes associated with brain [3H]acetylcholine release.

Isolated nerve terminals were prepared from the neocortices and striate cortices of Fischer 344 rats from 6 to 26 months of age and then assayed for release of newly synthesized [3H]acetylcholine (ACh) triggered by secretagogues with different mechanisms of action: 35 mM K+, 10 microM veratridine and 5 microM A23187. Secretagogue-induced release of newly synthesized [3H]ACh decreased with age in both brain regions, with reductions in A23187-induced release paralleling those seen with depolarizing agents. This observation was consistent with the hypothesis that aging attenuates the release-triggering ability of calcium ions coincident with or before it affects voltage-sensitive calcium influx. In neocortex, phorbol-stimulated translocation of protein kinase C (PKC) activity was attenuated in isolated nerve terminals concomitantly with A23187-induced release deficits. These results suggest that one of the earliest deficits in the ACh-release process may involve intracellular calcium potency, which may be associated with the onset of functional PKC deficits. Both brain regions also displayed gradual, age-related reductions in [3H]ACh synthesis, but this effect was more pronounced in the striatum. Choline acetyltransferase (CAT) activity decreased only in the striatum with aging.

Acetylcholine↗

PubMed1993

Recovery of [3H]acetylcholine synthesis after AF64A-treatment in primary, neuron-enriched, rat septal-hippocampal and striatal cultures.

Neuron-enriched cultures prepared from several different rat brain regions were incubated with 10 microM or 30 microM monoethylcholine mustard aziridinium ion (AF64A) under conditions (1 h, 37 degrees C in Krebs Ringer buffer) that reduced acetylcholine (ACh) synthesis coupled to high-affinity choline uptake, without affecting choline acetyltransferase activity. Co-cultures of septum-hippocampus and cultures of striatum were similarly sensitive to the AF64A-induced inhibition of ACh synthesis. However, ACh-synthesis recovered more rapidly in the striatal cultures than in septal-hippocampal co-cultures after AF64A washout. In septal-hippocampal co-cultures, neither tunicamycin (20 micrograms/ml) nor cycloheximide (0.5 microgram/ml) had any effect on the basal synthesis of ACh or its recovery within 24 h following 10 microM AF64A washout. However, the recovery of ACh synthesis in these co-cultures after 30 microM AF64A-washout was blocked by either tunicamycin or cyclohexamide. Neither tunicamycin nor cyclohexamide interfered with ACh-synthesis recovery after washout of 30 microM AF64A in striatal cultures. These studies suggest that the turnover of high-affinity choline transporters can be modulated in a brain-region specific manner in intact primary neuronal cultures.

Acetylcholine↗

PubMed1993

Effects of membrane peroxidation on [3H]acetylcholine release in rat cerebral cortical synaptosomes.

[3H]Acetylcholine (ACh) release, malonaldehyde formation and 45calcium-uptake were measured in rat cerebral cortical nerve terminal that were exposed to various concentrations of ferrous and ascorbate ions. At a constant molar ratio of 25:1, ferrous:ascorbate, these ions increased malonaldehyde (MA) synthesis in a concentration-dependent manner. Treatment with these ions in the same ratio also induced a dose-related inhibition of the K(+)-depolarization-induced release of newly synthesized [3H]ACh. Combined exposure to Fe2+/ascorbate also reduced calcium ionophore A23187-induced [3H]ACh release. Neither ferrous nor ascorbate ions alone altered depolarization- or ionophore-induced [3H]ACh release over this concentration range. Depolarization- and A23187-induced 45calcium uptake were not affected by peroxidation, suggesting that membrane peroxidation influenced some process in the release-process subsequent to calcium influx in a manner similar to what is observed during aging.

Acetylcholine↗

PubMed1988

Insulin receptors in the brain: structural and physiological characterization.

The present study was conducted to characterize insulin receptors and to determine the effects of insulin in synaptosomes prepared from adult rat brains. Binding of 125I-insulin to synaptosome insulin receptors was highly specific and time dependent: equilibrium binding was obtained within 60 minutes, and a t1/2 of dissociation of 26 minutes. Cross-linking of 125I-insulin to its receptor followed by SDS-PAGE demonstrated that the apparent molecular weight of the alpha subunit of the receptor was 122,000 compared with 134,000 for the liver insulin receptor. In addition, insulin stimulated the dose-dependent phosphorylation of exogenous tyrosine containing substrate and a 95,000 MW plasma membrane associated protein, in a lectin-purified insulin receptor preparation. The membrane associated protein was determined to be the beta subunit of the insulin receptor. Incubation of synaptosomes with insulin caused a dose-dependent inhibition of specific sodium-sensitive [3H]norepinephrine uptake. Insulin inhibition of [3H]norepinephrine uptake was mediated by a decrease in active uptake sites without any effects in the Km, and was specific for insulin since related and unrelated peptides influenced the uptake in proportion to their structural similarity with insulin. These observations indicate that synaptosomes prepared from the adult rat brain possess specific insulin receptors and insulin has inhibitory effects on norepinephrine uptake in the preparation.

Animals↗

PubMed1987

Insulin receptors and insulin action in dissociated brain cells.

The present study was conducted to characterize insulin receptors and insulin action in rat brain cells. Binding of [125I]insulin to cells obtained by mechanically dissociating rat brains was 86% specific, time-dependent and reached equilibrium within 90 min. The t1/2 of association was 14 min and t1/2 of dissociation was 8 min. Scatchard analysis demonstrated the typical curvilinear plot providing high affinity (0.03 nM) and low affinity (6.6 nM) binding sites. The total number of binding sites were 0.15 pmol/mg protein. Crosslinking of [125I]insulin to its receptors on dissociated brain cells followed by SDS-PAGE and autoradiography showed that the alpha-subunit of the receptor had a molecular weight of 122,000. This was in contrast with a molecular weight of 134,000 for the liver alpha-subunit. Incubation of dissociated brain cells with insulin resulted in a concentration-dependent inhibition of total [3H]norepinephrine (NE) uptake. This inhibitory effect of insulin on [3H]NE uptake was sodium ion-dependent suggesting that 80-90% of the sodium ion-dependent uptake was insulin-sensitive. Incubation of lectin-purified insulin receptors with insulin resulted in a time- and concentration-dependent stimulation of phosphorylation of the tyrosine residue of an exogenous substrate poly (Glu, Tyr) (4:1). In addition, insulin also stimulated the autophosphorylation of the beta-subunit of the insulin receptors. These observations corroborate our contention that insulin exerts neuromodulatory effects mediated by the specific insulin receptors in the brain.

Animals↗

PubMed1987

Effects of nucleus basalis lesions on the muscarinic and nicotinic modulation of [3H]acetylcholine release in the rat cerebral cortex.

Presynaptic muscarinic and nicotinic receptors in the cerebral cortex reportedly inhibit and increase acetylcholine (ACh) release, respectively. In this study, we investigated whether these receptors reside on cholinergic nerve terminals projecting to the cerebral cortex from the nucleus basalis magnocellularis (nbm). Adult male rats received unilateral infusions of ibotenic acid (5 micrograms/1 microliter) in the nbm. Two weeks later, cerebral cortical cholinergic markers (choline acetyltransferase activity, high-affinity choline uptake, and coupled ACh synthesis) were significantly reduced in synaptosomes prepared from the lesioned hemispheres compared to contralateral controls. The depolarization-induced release of [3H]ACh from these synaptosomes was also reduced in the lesioned hemispheres, reflecting the reduced synthesis of transmitter. However, the nbm lesions had no effect on the inhibition of release induced by 100 microM oxotremorine. Synaptosomal [3H]ACh release was not altered by nicotine or the nicotinic agonists anabaseine and 2-(3-pyridyl)-1,4,5,6-tetrahydropyrimidine. Nicotine (10-100 microM) did increase [3H]ACh release in control and lesioned hemispheres in cortical minces, but to a similar extent. These results suggest that neither muscarinic nor nicotinic receptors modulating ACh release reside on nbm-cholinergic terminals.

Acetylcholine↗

PubMed1987

Ubiquitin-directed antibodies inhibit neuronal transporters in rat brain synaptosomes.

Affinity-purified antibodies specific for ubiquitin were found to inhibit the sodium-dependent uptake of [3H]choline, gamma-[3H]aminobutyric acid [( 3H]GABA), [3H]glutamate, [3H]norepinephrine, [3H]aspartate, and [3H]serotonin in rat cerebral cortical synaptosomes at a low concentration (10 micrograms/ml). These antibodies (termed anti-Ub) had no effect on the sodium-independent uptake of these substances or their calcium-dependent efflux. Synaptosomal [3H]deoxyglucose uptake was not affected in normal Krebs Ringer buffer containing 10 mM glucose, but was inhibited in glucose-free medium. Other nonneuronal sodium-dependent transport processes were found to be unaffected by 10 micrograms/ml anti-Ub, suggesting that anti-Ub does not bind indiscriminantly to sodium-binding sites on sodium-dependent organic solute transporters. Finally, anti-Ub inhibited sodium-dependent [3H]GABA and [3H]glutamate uptake in plasma membrane ghosts, devoid of membrane potential, which were derived from rat cerebral cortical synaptosomes. These results suggest that neuronal transporters or sites proximal to them may be ubiquitinylated on the plasma membrane surface.

Animals↗

PubMedDate not supplied

Effects of peroxidation and aging on rat neocortical ACh-release and protein kinase C.

Cerebral cortical synaptosomes were prepared from 2- or 24-month-old Fischer 344 rats and exposed to a peroxidizing condition (50 microM ferrous ions and 2 microM ascorbate ions) before measuring either the release of newly synthesized [3H]acetylcholine (ACh) or protein kinase C activity (PKC). Several secretagogues with different mechanisms of action and different responses to aging were used to trigger release: K+ depolarization (5 mM-60 mM), calcium ionophore A23187 (1-10 micrograms/ml), and 4-aminopyridine (0.1-10 mM). Aging reduced K+ depolarization-induced release at every K+ concentration studied, reduced A23187-induced release at low but not high concentrations and did not affect 4-aminopyridine-induced release. Membrane peroxidation of synaptosomes from 2-month-old rats altered the response to secretagogues to match that seen in 24-month-old rats. Membrane peroxidation also attenuated the A23187-stimulated translocation of free to bound synaptosomal PKC activity in 2-month-old but not 24-month-old animals. These results suggest that membrane peroxidation may mimic some age-related deficits in secretagogue-induced [3H]ACh release.

4-Aminopyridine↗