Duane K. Rorie

Functional Anatomy of the Brachial Plexus Sheaths

The brachial plexus sheath was examined in cadavers by suing a combination of anatomic dissection, histologic preparations, and x-rays made after injection of x-ray contrast media, and in surgical patients by using computed tomography (CT) dye studies. The connective tissue forming the sheath was organized more densely proximally near its origin and became loosely organized distally as it ended by joining the medial intermuscular septum of the arm. The connective tissue forming the sheath extends inward, forming septa between components of the plexus. Thus, the sheath is a multicompartmented structure, formed by the thin connective tissue sheath surrounding the plexus and by the septa which extend inward from the sheath. A fascial compartment is created for each nerve, and this compartment serves to define the anatomic limits of that nerve. These compartments have potential clinical importance and implication in the techniques for brachial plexus block. They serve functionally to limit the circumferential spread of injected solutions of local anesthetics. These studies also indicate that injected anesthetic solutions spread easily in a longitudinal manner up and down the nerve and remain compartmentalized. The data presented here provide a rational explanation for the not uncommon occurrence of a profound block of rapid onset in one nerve, yet partial or absent block in other nerves, following any of the techniques of brachial plexus anesthesia.

Assessment of block of the sciatic nerve in the popliteal fossa.

Success of block of the sciatic nerve in the popliteal fossa in 130 patients was assessed by an anesthesiologist at the time of surgery. The patients were evaluated for complications by the anesthesiologist during postoperative rounds and by the orthopedic surgeon at the 1-month follow-up visit. Acceptance of the block by the patient was judged by answers on a questionnaire filled out by the patients after they had gone home. The questionnaire was designed to determine satisfaction with the block, discomfort associated with performance of the block, and whether sensations suggestive of paresthesias or other complications not evident at the time of discharge from the hospital had occurred. Of 119 patients responding to the questionnaire, 105 (88.2%) expressed overall satisfaction with the anesthesia. Two patients described sensations compatible with postoperative paresthesias, and two others described sensations that may have been paresthesias; in none did the sensations last longer than 1 month. Assessment of the blocks by the anesthesiologist in all 130 patients in the study revealed that anesthesia satisfactory for completion of the operative procedure was achieved in 107 (82.3%). General anesthesia was needed in eight patients (6.2%), and in 15 patients (11.5%) intravenous sedation or injection of the site of surgical incision with local anesthesia (or both) was needed.

Concurrent separation of catecholamines, dihydroxyphenylglycol, vasoactive intestinal peptide, and neuropeptide Y in superfusate and tissue extract

A method is described for separation and quantification of 3,4-dihydroxyphenylglycol (DO-PEG), norepinephrine (NE), dopamine (DA), vasoactive intestinal peptide (VIP), and neuropeptide Y (NPY) from single samples of tissue homogenate and from superfusate from in vitro dog blood vessel preparations using cartridges containing 0.4 g of octadecylsilane (Sep-Pak C-18). Samples were passed through the cartridge at pH 7.4. A step-gradient system was used to first selectively desorb the catechols (DOPEG, NE, DA) with a moderately polar eluent; subsequently VIP and NPY were eluted with 2.5 ml of a mixture of 1% trifluoroacetic acid, 80% acetonitrile. Five Sep-Pak catechol eluents were tested. Catechols were quantified by HPLC with electrochemical detection and peptides by radioimmunoassay. An HPLC solvent system is described which is particularly useful for chromatography of the more hydrophilic catechols DOPEG, 3,4-dihydroxymandelic acid, and 3,4-dihydroxyphenylalanine concurrently with catecholamines. For superfusion studies, sample cleanup time was reduced to about 4 min per sample by attachment of the cartridges directly to the bottom of the superfusion chamber. Superfusate was subsequently pulled through the cartridges immediately after they were passed over the tissue. Batches of 12 high-speed tissue supernates were processed through the method in about 30 min. The method was used to analyze DOPEG, NE, DA, VIP, and NPY in various rat and dog tissues. The values obtained were similar to values obtained previously by other methods. Because the catechols and peptides are separated from a single sample, the method has several advantages over those described previously; e.g., it is rapid, simple, and more sensitive.

Intraoperative and External Beam Irradiation With or Without Resection: Mayo Pilot Experience

At our institution, intraoperative radiation therapy (IORT) with an electron beam has been administered as a single boost dose of 1,000 to 2,000 cGy (rad) in combination with 4,500 to 5,000 cGy (rad) of fractionated external beam irradiation. From April 1981 to July 1983, 50 patients received such treatment, and results are analyzed in detail in this article. All patients had locally advanced disease (initially unresectable for cure, residual after resection, or recurrent), and the main disease sites were gastrointestinal (pancreatic, colorectal, and biliary tumors) and soft tissue (sarcomas). Disease-free survival to date has been excellent in our colorectal and biliary subsets of patients. Although local progression has not been a major problem in patients with unresectable pancreatic lesions, failures in the liver and peritoneal cavity have been excessive, and treatment strategies have been altered in an attempt to decrease the frequency of such failures. Although both short-term and long-term morbidity are acceptable, pilot trials with use of radiation-dose modifiers are planned to determine whether the therapeutic ratio of local control to associated complications can be improved even further.

Free and Conjugated Amines in Human Lumbar Cerebrospinal Fluid

Significant amounts of acid‐hydrolyzable conjugates of 3,4‐dihydroxyphenylethylamine, norepinephrine, and 5‐hydroxytryptamine were detected in lumbar CSF from 22 awake unpremedicated healthy individuals. In the CSF samples, the amounts of conjugated amines almost always exceeded the amounts of free amines, but were less than the amounts of the acid metabolites 3,4‐dihydroxyphenylacetic acid, homovanillic acid, and 5‐hydroxyindoleacetic acid.

Nitric oxide modulates evoked catecholamine release from canine adrenal medulla.

Nitric oxide has various actions, acting in a neurotransmitter-like role and also as a paracrine messenger between vascular endothelial and smooth muscle cells. This study was done to determine whether endogenous nitric oxide has a role in modulating evoked catecholamine release from the canine adrenal medulla. Isolated adrenal glands were perfused with Krebs-Ringer solution as a control, or with Krebs-Ringer solution containing either N(G)-monomethyl-L-arginine (L-NMMA; 3x10(-4) M) to non-selectively inhibit nitric oxide synthase or 7-nitroindazole (10(-4) M), a relatively selective inhibitor of neuronal nitric oxide synthase. Catecholamine release was evoked using the nicotinic cholinergic agonist 1,1-dimethyl-4-phenylpiperazinium iodine. From the collected perfusate epinephrine, norepinephrine, and dopamine were measured by high performance liquid chromatography. Previous studies have shown that in the presence of L-NMMA, basal releases of epinephrine, norepinephrine and dopamine are increased. 7-Nitroindazole had no effect on basal catecholamine release, suggesting that nitric oxide from an endothelial source was responsible for the inhibition of basal catecholamine release from the adrenal medulla. Epinephrine and norepinephrine releases were augmented when either of the nitric oxide synthase inhibitors was added during submaximal nicotinic stimulation, indicating that endogenous nitric oxide inhibited release of epinephrine and norepinephrine. Both neuronal and endothelial nitric oxide synthases appeared to be responsible for this inhibition. In summary, these studies suggest that nitric oxide, from both neuronal and endothelial sources, modulates evoked catecholamine release from canine adrenal medulla, while nitric oxide from an endothelial source is most likely responsible for modulation of catecholamine release under basal conditions.

Nitric oxide reduces basal efflux of catecholamines from perfused dog adrenal glands.

Norepinephrine, epinephrine, dopamine, and both the free and extended forms of [met]enkephalin spontaneously efflux from adrenal glands under basal conditions. The present study was done to determine whether nitric oxide has a regulatory role in these effluxes. Isolated adrenal glands (n = 63) from mongrel dogs were perfused retrogradely with Krebs-Ringer solution. In some experiments NG-monomethyl-L-arginine (3 x 10(-4) M), an inhibitor of nitric oxide synthesis, was added to the perfusate. In other experiments one of the nitric oxide donors, 3-morpholinosydnonimine (10(-7) M or 10(-5) M) or sodium nitroprusside (10(-6) M or 10(-4) M) was added. Norepinephrine, epinephrine, dopamine and their metabolites 3,4-dihydroxyphenylglycol and 3,4-dihydroxyphenylacetic acid in perfusates were quantitated by high performance liquid chromatography with electrochemical detection and in some experiments the [met]enkephalins were determined by radioimmunoassay. In the presence of NG-monomethyl-L-arginine, the basal effluxes of norepinephrine, epinephrine, and dopamine were significantly increased from control, but the effluxes of the free and extended forms of the [met]enkephalins were not changed. The effects of NG-monomethyl-L-arginine on catecholamine efflux were reversed in the presence of L-arginine (10(-3) M). Sodium nitroprusside (10(-6) M) inhibited effluxes of norepinephrine and epinephrine and 3-morpholinosydnonimine had no effect on these effluxes. Dopamine efflux appeared to be under different controls from those of norepinephrine and epinephrine since dopamine efflux was unaffected by sodium nitroprusside and was decreased over time by 3-morpholinosydnonimine (10(-7) M). It is concluded that endogenously produced nitric oxide inhibits the basal efflux of norepinephrine, epinephrine, and dopamine from isolated dog adrenal glands; this inhibition appears to be near maximal for norepinephrine and epinephrine but not for dopamine.

Effects of L-dopa and L-tyrosine on release of free and conjugated dopamine, homovanillic acid and dihydroxyphenylacetic acid from slices of rat striatum

Conjugation (presumably with sulfate) is a demonstrable metabolic pathway for 3, 4-dihydroxyphenylethylamine (dopamine, DA) in brain. Studies were done to determine whether conjugation becomes of increased significance in the presence of precursors of DA. The effects of 3, 4-dihydroxyphenylalanine (L-DOPA) and L-tyrosine on the efflux of free and conjugated DA, 3, 4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid from slices from striatum in rats were studied under quiescent conditions and during release evoked by 40 mM K+ or by 5 X 10(-5) M phenylethylamine (PEA). Conjugated DA was present in the basal efflux from striatal slices and the amounts present were increased during evoked release. More conjugated DA was present in superfusate during K+-evoked release than during PEA-evoked release. L-Tyrosine (5 X 10(-4) M or 5 X 10(-5) M) had little effect on the efflux of conjugated DA, but decreased the amounts of free DA released by PEA, and attenuated the increase in DOPAC that occurred during K+-evoked release of transmitter. L-DOPA (5 X 10(-5) M) increased the formation of conjugated DA, but to a lesser extent than that of free DA or of DOPAC. Thus even after the addition of precursors, conjugation remains a minor metabolic pathway for DA relative to O-methylation or oxidative deamination. The data also suggest that conjugation of DA occurs chiefly outside of the dopaminergic neurons in striatum.

The specific activity of retained and released norepinephrine in dog saphenous vein prelabeled with radiolabeled norepinephrine

Abstract The specific activities of released and retained norepinephrine (NE) in the isolated superfused dog saphenous vein preparation, prelabeled with [ 3 H]NE, have been determined. Norepinephrine was isolated from extracts of vein superfusate and its concentrations were measured by high pressure liquid chromatography with electrochemical detection. The specific activity of NE in superfusate collected under basal conditions was lower than that of NE in veins after electrical stimulation or in parallel unstimulated veins. However, NE released during electrical stimulation had a specific activity 1.5 to 3 times higher than the NE in the veins. Thus, NE taken up by neuronal uptake in the prelabeling procedure enters a pool from which is preferentially released by electric stimulation. In addition, NE is released from different compartments during basal conditions and during electric stimulation.

Dihydroxyphenylalanine and Dopamine Are Released from Portal Vein Together with Noradrenaline and Dihydroxyphenylglycol During Nerve Stimulation

Abstract: The overflows of 3,4‐dihydroxyphenylalanine, dopamine, noradrenaline, and 3,4‐dihydroxyphenylglycol in canine portal vein superfused in vitro were studied before, during, and after depolarization of sympathetic nerve endings. The four compounds were separated from superfusate and from tissue on Sep‐Pak C‐18 cartridges and quantified by HPLC with electrochemical detection. Physiological and biochemical methods were used to show that the compound released was most probably 3,4‐dihydroxyphenylalanine; the identity of the other endogenous compounds has been established previously. Release of 3,4‐dihydroxyphenylalanine was calcium and frequency dependent, inhibited by α‐m‐L‐p‐tyrosine (an inhibitor of tyrosine hydroxylase) and augmented by 3‐hydroxybenzylhydrazine (an inhibitor of aromatic amino acid decarboxylase). The overflows of dopamine, noradrenaline, and 3,4‐dihydroxy phenylglycol from the vein were calcium and frequency dependent. It was estimated that under control conditions, ∼ 80% of the total 3,4‐dihydroxyphenylalanine that was synthesized was directed to catecholamine biosynthesis, ∼8% overflowed from the vein, and ∼ 14% remained unchanged within the tissue. It is concluded that 3,4‐dihydroxyphenylalanine and dopamine are released together with noradrenaline and 3,4‐dihydroxyphenylglycol from portal vein upon nerve depolarization.