Differential gene expression in a murine model of cancer cachexia.

Murine adenocarcinoma 16 (MAC16) tumors and cell lines induce cachexia in NMRI nude mice, whereas histologically similar MAC13 tumors do not. After confirming these findings in BALB/c nude mice, we demonstrated that this tissue wasting was not related to decreased food intake or increased total body oxidative metabolism. Previous studies have suggested that MAC16's cachexigenic properties may involve the production of tumor-specific factors. We therefore screened for genes having increased expression in the MAC16 compared with the MAC13 cell line by performing hybridization to a murine cDNA expression array, by generation and comparison of cDNA libraries from each cell line, and by PCR-based subtractive hybridization. Northern blot hybridization was performed to confirm differences in transcript expression. Transcripts encoding insulin-like growth factor binding protein-4, cathepsin B, ferritin light and heavy chain, endogenous long-terminal repeat sequences, and a viral envelope glycoprotein demonstrated increased expression in the MAC16 cell line. The roles of a number of these genes in known metabolic pathways identify them as potential participants in the induction of cachexia.

The safety and efficacy of parent-/nurse-controlled analgesia in patients less than six years of age.

UNLABELLED: Over the past 5 yr, we have treated nonsurgical and postoperative pain in children <6 yr of age by using a patient-controlled analgesia pump to deliver small-dose continuous IV opioid infusions supplemented by parent- and nurse-controlled opioid bolus dosing. We call this technique parent-/nurse-controlled analgesia (PNCA). Because the safety and efficacy of PNCA have not been previously evaluated, we have undertaken a prospective, 1-yr observational study to determine patient demographics, effectiveness of analgesia, and the incidence of complications (pruritus, vomiting, and respiratory depression) in patients receiving PNCA. Data were collected on 212 children (98 female) who were treated on 240 occasions with PNCA for episodes of pain. Patients averaged 2.3 +/- 1.7 yr of age and 11 +/- 5 kg, and received a median of 4 (range 2-54) days of PNCA therapy. Maximum daily pain scores were < or =3/10 (objective pain scale) or < or =2/5 (objective or self-report pain scale) in more than 80% of all occasions of PNCA use. PNCA usage was associated with an 8% incidence of pruritus and a 15% incidence of vomiting on the first day of treatment. Nine children studied received naloxone, four (1.7%) for treatment of PNCA-related apnea or desaturation. All had improvement in their symptoms after naloxone administration. IMPLICATIONS: Parent-/nurse-controlled analgesia provided effective pain relief in most children <6 yr of age experiencing nonsurgical or postoperative pain. The observed incidence of vomiting and pruritus was similar to that seen in older patients treated with patient-controlled analgesia. However, significant respiratory depression, although uncommon, did occur, thus reinforcing the need for close patient monitoring.

Cerebral blood flow regulation in neonatal rabbits is altered by chronic cocaine administration.

Maternal cocaine abuse has several deleterious effects in the newborn, including perinatal asphyxia, hypoxia, and hypercapnia. We hypothesized that chronic cocaine exposure during development may alter cerebral blood flow (CBF) regulation. We studied 16 neonatal rabbits that had received cocaine (20 mg/kg, i.p. b.i.d.) or saline since birth. Changes in CBF were measured by laser doppler flowmetry before (baseline), and during hypercapnia (FiCO2 = 7.5%), hypoxia (FiO2 = 12%), and asphyxia (apnea for 1 min). During hypercapnia, CBF increased less in cocaine than in control animals (28 +/- 3% vs. 69 +/- 10%, P < 0.05). During hypoxia, CBF increased similarly in both groups. During reventilation after asphyxia, CBF increased more in cocaine than in control animals (391 +/- 52% vs. 225 +/- 43%, P < 0.05). Chronic cocaine exposure during brain development appears to alter CBF regulation to hypercapnia and asphyxia, which may put the drug exposed newborn at risk for neurologic injury around birth.

Effect of dopamine antagonism on the behavioral and hemodynamic responses to cocaine in piglets.

Cocaine (1.5 mg/kg i.v.) was administered to awake newborn piglets that were pretreated with either intravenous saline (placebo) or SCH23390, a dopamine antagonist, to study dopamine's role in cocaine's vascular and behavioral actions. In the placebo group, cocaine increased the locomotor activity and cerebellar and cardiac blood flow (31 +/- 36 and 72 +/- 66%), but decreased choroid plexus and renal blood flow (47 +/- 23 and 18 +/- 19%). In the SCH23390-treated group, cocaine did not affect organ blood flow or locomotor activity. Cocaine transiently increased the mean arterial blood pressure in both groups (10 +/- 7 and 18 +/- 13%). These data indicate that the behavioral and blood flow responses to cocaine in cerebellum, choroid plexus, heart, and kidneys are mediated by dopamine, whereas the arterial pressor response to cocaine is not.

Effect of chronic cocaine exposure on carotid artery reactivity in neonatal rabbits.

Chronic cocaine abuse by pregnant women results in chronic neonatal drug exposure. In adults, chronic cocaine use alters neurotransmitter concentrations and receptor dose-response relationships. Similar changes may also occur in the neonatal cerebrovasculature after in utero cocaine exposure. This study examined the effect of chronic cocaine exposure on internal carotid artery reactivity to norepinephrine, serotonin, acetylcholine, sodium nitroprusside, adenosine, and cocaine in neonatal rabbits. Internal carotid artery rings were isolated from 16 to 20 day old rabbits that had received cocaine (20 mg/kg IP BID, n = 8) or saline (n = 8) from 5 days of age and were studied in organ baths using standard in vitro techniques. Chronic treatment with cocaine decreased the half-maximal relaxant response (ED50) to adenosine (control 6.9 +/- 1.8 vs cocaine 3.5 +/- 0.99 microM, p = 0.05). The half-maximal contractile responses (EC50) to norepinephrine and serotonin and the half-maximal relaxant responses (ED50) to acetylcholine and sodium nitroprusside were similar between groups. The threshold concentration of cocaine that induced vessel contraction was altered by chronic cocaine exposure (control group 10(-6) M vs chronic cocaine group 10(-4) M). We conclude that chronic cocaine exposure sensitizes carotid arteries to the relaxant effects of adenosine. In addition, chronic cocaine exposure desensitizes carotid arteries to the contractile effects of acute cocaine. These vasoreactivity changes may underlie altered cerebrovascular responses to asphyxia and play a role in the pathogenesis of postnatally acquired brain injury in critically ill "crack" babies.

Ethanol, morphine and barbiturate alter the hemodynamic and cerebral response to cocaine in newborn pigs.

Newborns delivered to cocaine-abusing mothers are often exposed to other concurrently consumed illicit drugs, which may alter the hemodynamic and cerebral response to cocaine. This study examined the interaction of ethanol, morphine or barbiturate with cocaine on mean arterial pressure (MAP), cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in newborn pigs. CBF, CMRO2 and cerebral O2 extraction (CEO2) were measured before and 4 and 10 min after cocaine (1.5 mg/kg i.v.) was administered in piglets that were awake, or pretreated with morphine, ethanol or pentobarbital. In awake piglets, cocaine increased CMRO2 and CEO2 while it had no significant effect on CBF. Conversely, in morphine- and ethanol-pretreated piglets, cocaine decreased CMRO2, decreased CBF and had not effect on CEO2. In awake piglets, cocaine increased MAP, whereas in morphine- or ethanol-pretreated piglets, cocaine decreased MAP. In the pentobarbital group, cocaine had no effect. These data demonstrate that other drugs of abuse alter the hemodynamic and cerebral effects of cocaine in the immature animal and may contribute to the central nervous system abnormalities in 'crack babies'.

The effect of fentanyl, sufentanil, and alfentanil on cerebral arterioles in piglets.

The effect of fentanyl, sufentanil, and alfentanil on cerebral arterioles was determined in 17 halothane-anesthetized newborn piglets. A closed cranial window was inserted over the parietal cortex, and changes in the luminal diameter of pial arterioles were measured by intravital microscopy as increasing concentrations of opioid (10(-9)-10(-5) M) were suffused over the cortical surface. Each opioid caused a dose-dependent decrease in arteriolar diameter that was attenuated by coadministration of naloxone (10(-5) M). Fentanyl was more potent than either alfentanil or sufentanil. Naloxone alone had no effect at concentrations < or = 10(-5) M, suggesting that endogenous opioids contribute little to resting cerebrovascular tone. These results indicate that fentanyl, sufentanil, and alfentanil produce cerebral vasoconstriction by action at an opioid receptor and that their vasoconstrictive potency appears to differ from their analgesic potency.

Molecular motion of DNA as measured by triplet anisotropy decay.

We have used triplet anisotropy decay techniques to measure the internal flexibility and overall rotational motion of DNA, covering a time range from 15 ns to 200 mus. Nearly monodisperse DNA fragments 65--600 base pairs long were studied by using the intercalating dye methylene blue as a triplet probe. We found that the slow end-over-end tumbling of short DNA fragments (less than or equal to 165 base pairs) is as predicted for a rigid rod. As expected, a longer DNA fragment (600 base pairs) experiences slow segmental motion of its helix axis. We found that, at the earliest times, anisotropy decays more rapidly than expected for a rigid rod, suggesting that, when bound, methylene blue monitors fast internal motion of the helix. Since the rod-like end-over-end tumbling of short fragments rules out fast bending motions, we conclude that the fast components of DNA anisotropy decay are due to twisting motion of the helix, occurring with a time constant near 50 ns.