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Biomedical subjects

R Gilmore

Publications and source records attributed to R Gilmore.

117 records · Page 7Linked to original sources
PubMed1979

Rotational relaxation times of 1,6-diphenyl-1,3,5-hexatriene in phospholipids isolated from LM cell membranes. Effects of phospholipid polar head-group and fatty acid composition.

Phospholipids were isolated from mitochondrial, microsomal, and plasma membranes of LM cells and fractionated into individual phospholipid classes on silicic acid columns. The fatty acid composition and the rotational relaxation time of 1,6-diphenyl-1,3,5-hexatriene (DPH) were determined for each phospholipid class. Sphingomyelin was the only phospholipid isolated from LM cell membranes that showed a phase transition within the temperature range investigated, 5-40 degrees C. The rotational relaxation times for DPH were lowest in phosphatidylcholine in all the membrane fractions. Phosphatidylcholine isolated from the three membrane fractions of choline-supplemented cells had similar rotational relaxation times and phosphatidylcholine isolated from microsomal membranes of linoleate-supplemented cells had lower rotational relaxation times. The results indicate that the differences in the rotational relaxation times of DPH between mitochondrial, microsomal, and plasma membrane phospholipids could be explained primarily by differences in the polar head-group composition, while differences in the fatty acid composition had only a minor effect. This provides a basis for understanding how the different lipid components in these cells contribute to membrane fluidity.

Animals↗
PubMed1978

Deuterium nuclear magnetic resonance investigation of the effects of proteins and polypeptides on hydrocarbon chain order in model membrane systems.

Deuterium Fourier-transform nuclear magnetic resonance spectra have been obtained of 1-myristoyl 2-(14,14,14-trideutero)myristoyl phosphatidylcholine bilayers at 34.1 MHz by using the quadrupole echo pulse technique. Thereby, we have investigated the effects upon the deuterated dimyristoyl phosphatidylcholine bilayers of the following proteins and polypeptides: gramicidin A, bacteriophage f1 coat protein, beef brain myelin proteolipid apoprotein, cytochrome b(5), and cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). Above T(c), the transition temperature between the gel and liquid crystal phases, the quadrupole splitting of the deuterium-labeled methyl group is reduced or collapsed in the presence of protein or polypeptide. No evidence has been found for ordered "boundary lipid." Below T(c), the spectra show that the hydrocarbon chains are prevented from crystallizing by the protein (or polypeptide) incorporated in the membrane. Similar disordering effects above T(c) are also seen when an unsaturated lipid, 1-(16,16,16-trideutero)palmitoyl 2-palmitoleyl phosphatidylcholine is complexed with cytochrome oxidase.

Journal Article↗
PubMedDate not supplied

Integral membrane glycoprotein properties of the prohormone pro-transforming growth factor-alpha.

Transforming growth factor-alpha (TGF-alpha) is a mitogenically active polypeptide hormone produced by acutely proliferating neoplastic and embryonic tissues. Molecular cloning of TGF-alpha cDNA from human and rat has indicated that this factor is synthesized as part of a larger precursor, proTGF-alpha. An intriguing feature of proTGF-alpha is that it contains a sequence of 24 hydrophobic amino acids following the bioactive TGF-alpha sequence. Similar hydrophobic sequences present in transmembrane proteins are cotranslationally anchored into the phospholipid bilayer of the rough endoplasmic reticulum, suggesting the possibility that pro TGF-alpha might be an integral membrane protein. Other secretory proteins including all known prohormones lack membrane anchoring sequences and are completely translocated across the endoplasmic reticulum membrane. To address the question of whether proTGF-alpha is as an integral membrane protein we have translated rat proTGF-alpha mRNA transcripts in the presence of rough endoplasmic reticulum membrane vesicles. The results indicate that proTGF-alpha is synthesized as an integral membrane glycoprotein. The 50-amino-acid TGF-alpha sequence in proTGF-alpha is exposed to the fluid extracellular phase where it can be released after cleavage by the appropriate enzyme.

Amino Acid Sequence↗
PubMedDate not supplied

Chronic intractable epilepsy as the only symptom of primary brain tumor.

We identified 39 patients with chronic epilepsy (seizures > or = 2 years) proven to have primary brain tumors. These cases represent approximately 12% of the surgery cases for epilepsy in the same period. Mean age of seizure onset was 13.2 years: mean duration before operation was 10.5 years. Thirty-eight of 39 had normal neurologic examination. Twenty-six tumors were temporal, 7 were frontal, 4 were parietal, and 2 were occipital. Nine of 26 (34.6%) of the temporal group had contralateral interictal EEG spikes. Pathology was 15 ganglioglioma, 13 low-grade astroctoma, 4 oligodendroglioma, 2 low-grade mixed glioma, 1 pleomorphic xanthoastrocytoma, 2 dysembryoplastic neuroepithelial tumor, and 1 ependymoma. Postoperative seizure frequency (minimum follow-up 6 months) ranged from 15 to 16 seizure-free auras only in patients with temporal tumors and total gross tumor removal (mean follow-up 28 months) to 0 of 6 seizure-free in patients with extratemporal tumors who underwent subtotal resection or biopsy.

Adolescent↗
PubMedDate not supplied

Mirror focus: function of seizure frequency and influence on outcome after surgery.

The concept of the mirror focus (MF) implies that an actively discharging epileptiform region may induce similar paroxysmal behavior in a homologous site. In a group of patients with complex partial seizures (CPS) we investigated whether occurrence of a MF was influenced by certain clinical factors and whether surgical outcome was influenced by the presence of an MF. Factors studied included age at onset, duration, and total number of seizures. Patients had had CPS for > 3 years and had pathologically proven temporal lobe neoplasms. Seizure frequency was estimated by the history-taking physician. We estimated total seizure number by multiplying frequency by duration. Seven patients had MF, and 15 did not. Mean age at onset of seizures, duration of seizure disorder, and total seizure number did not vary statistically between the two groups of patients. All patients with an MF except 1 were seizure-free at follow-up. Ten of the 15 patients without MF were seizure-free. Three patients who were not seizure-free had had subtotal resection owing to tumor overlap with eloquent cortex. We conclude that an MF is not a contraindication to operation even when the preponderance of interictal spike activity is contralateral to the tumor or when seizures appear to arise from the MF on scalp EEG.

Adolescent↗
PubMedDate not supplied

Intraarterial use of sodium methohexital for provocative testing during brain embolotherapy.

PURPOSE AND METHODS: To assess its vascular effects and safety, we used sodium methohexital (Brevital)--an ultrashort-acting barbiturate--as the provocative intraarterial agent in a series of 30 patients with arteriovenous malformations at a 1% concentration and at doses of less than 5 mg per injection. Digital vascular imaging was performed just prior to and just after the injections. RESULTS: No angiographic or clinical evidence of apparent vasospasm occurred in the trial population (66 vascular pedicle injections in 30 patients). When functional tissue was perfused with 1-6 mg of the 1% Brevital solution, evidence of altered neurologic status became immediately apparent, but cleared within 2 minutes in all cases. None of the patients experienced either prolongation of the induced clinical symptoms or seizures to suggest any adverse effects related to either crystallization of the Brevital or the effects of injecting an alkaline solution in the cerebral circulation. CONCLUSION: Though the full effects of methohexital in the cerebral circulation remain to be elucidated, existing reports suggest it is a safe provocative agent for use prior to embolotherapy for brain arteriovenous malformations.

Cerebral Angiography↗