Quantitative determination of 2-hydroxy-3-methoxy-6 beta-naltrexol (HMN), naltrexone, and 6 beta-naltrexol in human plasma, red blood cells, saliva, and urine by gas liquid chromatography

Two gas liquid chromatographic methods differing mainly in sensitivity are described for the quantitative determination of 2-hydroxy-3-methoxy-6 beta-naltrexol (HMN), a minor metabolite of naltrexone (NT), in human body-fluids. The methods also incorporate simultaneous determinations of naltrexone and its major human metabolite, 6 beta-naltrexol (beta-OL), in urine, serum (or plasma), red blood cells (RBC), and saliva. Flame ionization detection of the bis-(trimethylsylil) trifluoroacetamide (BSTFA) derivatives provided sufficient sensitivity for quantitation of the bases in urine. However, lower levels in serum, RBC and saliva necessitated the use of more sensitive electron capture detection of the pentafluoropropionate (PFPA) derivatives of the bases. Because HMN and 6 beta-naltrexol PFPA derivatives have nearly identical gas chromatographic retention times, their separation was achieved by differential extraction, based on their different partition characteristics between aqueous and organic solvents. In the plasma of 4 subjects, 16 and 24 hrs. after 2 X 200 mg NT doses, the relative percentages were 23.1% HMN, 3.4% NT and 73.5% beta-OL. In urine samples collected at the same time as the blood samples the relative percentages were 14.4% HMN, 9.0% NT and 76.6% beta-OL. The nonpolar nature of HMN and the greater polarity of beta-OL may have influenced their differential distribution into RBCs and saliva. In the RBCs, 96.1% HMN and no significant amount of beta-OL was found, in saliva, 92.3% of beta-OL and no HMN was found.     

Disposition and metabolism of [3H] cocaine in acutely and chronically treated monkeys

Monkeys were chronically treated with cocaine, 1 mg/kg subcutaneously twice daily for the first week and four times daily for the subsequent 21 weeks, followed by the same dose of [³H] cocaine injected intravenously. The $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ values of cocaine in the plasma, cerebrospinal fluid, liver, kidney and heart of acutely and chronically treated monkeys were 1.32, 0.85; 0.91, 0.75; 1.60, 1.29; 0.90, 0.91; and 1.02, 0.91 h, respectively. In areas of the central nervous system (CNS) the values for the acute and chronic group ranged between 0.75 – 0.90 and 0.62 – 0.84 h, respectively. With the exception of the temporal cortex, cerebellum and caudate nucleus, the $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ were not significantly different in the two groups. Norcocaine, benzoylnorecgonine, benzoylecgonine, and minor amounts of ecgonine were the metabolites of cocaine in the brain of monkeys. Significant amounts of total radioactivity due to benoylnorecgonine and benzoylecgonine persisted in the CNS of chronically treated monkeys. Norcocaine constituted approximately 3, 21, 8, and 6% of the values of cocaine in the CNS areas in the acutely treated monkeys, and 14, 13, 14, and 16% in the chronically treated ones, 0.25, 0.5, 1 and 2 h after cocaine injection. A biphasic pattern of peak levels in the plasma and bile of chronically treated monkeys indicated enterohepatic circulation of cocaine. Brain to plasma and CSF to plasma ratios of cocaine were higher in the chronic than in the acute group. The amounts of cocaine excreted in urine and feces as a percentage of dose were 0.23 – 5.1 and 0.1 – 0.23 in the acute group, 0.54 – 7.0 and 0.1 – 0.14 in the chronic group. Major excretion of radioactivity occurred in urine within 24 h and the mean values of the total radioactivity in urine and feces (96 h) in the acute and chronic groups were 60.4 and 63.2% of the dose, respectively. Norcocaine, benzoylnorecgonine, benzoylecgonine, ecgonine methyl ester, ecgonine, and unidentified compounds were the urinary metabolites of cocaine in the two groups. The percentage of benzoylecgonine was higher, that of benzoylnorecgonine lower, in the chronic than in the acute group and the values of other metabolites were not markedly different in the two groups. Data support the postulate that chronic treatment of monkeys with cocaine does not produce dispositional tolerance.     

Non-adrenergic, non-cholinergic inhibitory responses to nerve stimulation in rat colonic circular muscle.

The nerve-mediated response to electrical field stimulation (EFS) in rat colonic circular muscle was investigated using the single sucrose-gap technique. EFS with a single pulse (0.4 ms, supramaximal voltage) elicited transient TTX-sensitive hyperpolarization (IJP) often followed by an 'off' depolarization associated with muscular contraction. No relaxation associated with the IJP could be seen unless tone was pharmacologically induced by carbachol (10(-6) M). IJPs were due to non-adrenergic, non-cholinergic (NANC) nerve activation since they were not affected by atropine (10(-7) M) or guanethidine (10(-6) M) superfusion. The mechanism underlying the IJP was presumably an increase in K+ conductance, and the NANC neurotransmitter might open largely apamin-sensitive, Ca(2+)-dependent K+ channels. Purines or vasoactive intestinal polypeptide (VIP) did not mimic the effects of NANC nerve stimulation. Therefore, the NANC inhibitory system, producing IJPs, in rat colonic circular muscle is not purinergic or VIPergic in nature.     

Skin blood flow changes during apneic spells in preterm infants

Changes in skin blood flow during apneic spells were determined in 18 preterm infants using a diode laser Doppler flow meter without light conducting fibres. Heart rate, nasal air flow, impedance pneumography, skin and incubator temperature and laser Doppler skin blood flow were recorded simultaneously in each infant. During 212 apneic spells with a duration of 11.6 ± 7.5 s (mean ± S.D.) (range 6.0–48.0 s), the laser Doppler skin blood flow was measured. In all children except one, the majority of the apneic spells was associated with a decrease in skin blood flow. During 155 apneic spells (73%) skin blood flow decreased significantly P < 0.025), the maximum decrease being 16.7 ± 14.8%, 28.5 ± 23.9% and 18.9 ± 16.1% (mean ± S.D.) for central, obstructive and mixed apneic spells, respectively. The decrease in skin blood flow started immediately after the beginning of apneic spells in 71%, the rest started with a mean delay of 3.4 s (range 0.1–7.0 s). No relation was found between the decrease in skin blood flow and the duration of the apneic spells. Thirty-four percent of the apneic spells were accompanied by bradycardia. In apneic spells accompanied by bradycardia the decrease in skin blood flow was not related to the fall in heart rate.     

Low seminal zinc bound to high molecular weight proteins in asthenozoospermic patients: evidence of increased sperm zinc content in oligoasthenozoospermic patients [published erratum appears in Hum Reprod 1998 Jun;13(6):1750]

Total seminal zinc concentration, seminal zinc fraction bound to high molecular weight proteins (HMW-Zn%) and zinc content in spermatozoa were assayed in the ejaculates of 90 asthenozoospermic patients subdivided into two study groups: normoasthenozoospermics (group I: n = 50) and oligoasthenozoospermics (group II: n = 40). The zinc concentrations of patients were compared with those of a control group of donors showing normal semen parameters. All samples were also investigated for their sperm membrane functional integrity by the hypo- osmotic swelling test (HOS). The results showed normal total zinc concentrations but very low HMW-Zn% values (P < 0.001) in seminal plasma of the two groups of asthenozoospermic patients compared to the controls. Furthermore higher zinc amounts (P < 0.001) were measured in spermatozoa of oligoasthenozoospermic patients compared to group I and to the control group. Oligoasthenozoospermics also displayed a lower HOS score (P < 0.001) compared to the other two groups. These data suggest that the increased unbound seminal zinc could contribute to the decrease of sperm motility in normoasthenozoospermic and oligoasthenozoospermic patients. A further impairment in sperm motility could occur in the oligoasthenozoospermic patients where the increase of seminal free zinc was followed by a major zinc uptake by spermatozoa. The higher intrasperm zinc content in these patients could be a reflection of their low sperm membrane functionality.      

Forehead skin blood flow in normal neonates during active and quiet sleep, measured with a diode laser Doppler instrument

Changes in forehead skin blood flow during active and quiet sleep were determined in 16 healthy neonates using a recently developed semi-conductor laser Doppler flow meter with-out light conducting fibres. Measurements were carried out at a postnatal age varying from 5 hours to 7 days. The two sleep states could be distinguished in 17 recordings. The mean skin blood flow values during active sleep were significantly higher (p less than 0.01) than those during quiet sleep, the mean increase being 28.1%. The variability of the flow signal, expressed as the coefficient of variation, changed significantly from 23.1% during active sleep to 18.2% during quiet sleep.