Fasting glycaemia to simplify screening for gestational diabetes

OBJECTIVE

Recommendations in Switzerland on screening for gestational diabetes endorse the International Association of Diabetes in Pregnancy Study Group consensus. As universal testing is time consuming and glucose loading is unpleasant, the recommendations include a simplification, not performing the glucose loading in women with fasting glycaemia <4.4 mmol/l. Our objective was to evaluate the diagnostic performance of this simplified strategy, compared with the complete test, in our population with a low prevalence of gestational diabetes.

DESIGN

We collected 2298 complete 75-g glucose tolerance tests. We simulated stopping the test, so avoiding the glucose loading and further glycaemia, if fasting glycaemia was <4.4 or ≥5.1 mmol/l.

SETTING AND POPULATION

Unselected pregnant women from Geneva and Basel, at 24-28 weeks of gestation.

METHODS

We calculated the sensitivity, and the percentage of women who would avoid the complete test with the strategy based on fasting glycaemia.

RESULTS

The prevalence of gestational diabetes was 10.9% in our population. Among 251 women with gestational diabetes, fasting glycaemia was ≥5.1 mmol/l in 119 women (47.4%), between 4.4 and <5.1 mmol/l in 78 women (31.1%) and <4.4 mmol/l in 54 women (21.5%). Proceeding with the complete test only in women with fasting glycaemia between 4.4 and <5.1 mmol/l will result in a sensitivity of 78.5%. This strategy would avoid glucose loading in 63.8% of women.

CONCLUSIONS

Screening with fasting glycaemia is an attractive alternative to universal screening with the complete 75-g glucose tolerance test. This strategy is, however, slightly less sensitive than previously reported in higher-risk populations.

TWEETABLE ABSTRACT

Fasting glycaemia can be considered as an alternative to the complete test for gestational diabetes screening.

Trends in antibiotic resistance of staphylococci over an eight-year period: differences in the emergence of resistance between coagulase positive and coagulase-negative staphylococci

The antimicrobial susceptibilities of 1058 Staphylococcus aureus and 2,163 coagulase-negative staphylococci (CNS) isolates obtained from clinical specimen between 1988 and 1995, were determined against 13 anti-staphylococcal antibiotics. During the study period the resistance of Staphylococcus aureus to ciprofloxacin, ceftazidime, and norfloxacin increased significantly by 7%, 4%, and 6%, respectively (p < or = 0.001). By comparison, the antibiotic resistance of CNS to ceftazidime, oxacillin, norfloxacin, ciprofloxacin, fusidic acid, and cefoxitin increased by 20%, 17%, 15%, 14%, 12% and 10%, respectively (p < or = 0.001). Invasive and noninvasive S. aureus had similar antibiotic resistance, whereas CNS invasive isolates were more resistant than noninvasive isolates to every antibiotics, except vancomycin and fusidic acid. These differences were significant (p < 0.001) for oxacillin, cefoxitin, and clindamycin. Our observations confirm that staphylococci and particularly CNS isolates show an important rate of increased resistance to the standard antimicrobials used for therapy, and that the rate of emergence of resistance differ considerably between coagulase-positive and coagulase-negative staphylococci.

Modulation of human chorionic gonadotrophin bioactivity during the first trimester of pregnancy

The objective of this study was to evaluate the bioactivity of human chorionic gonadotrophin (HCG) during first trimester pregnancy. This was done by means of a retrospective analysis of sera from patients with first trimester normal intrauterine and ectopic pregnancies. Serum samples were obtained from 38 women with amenorrhoea of <10 weeks. From these, 19 had a normal intrauterine pregnancy (IUP) and 19 an ectopic pregnancy (EP). Cases were allocated to either low serum immunoreactive HCG (HCGi), intermediate HCGi or high HCGi concentrations (HCGi <5000 mUI/ml, between 5000 and 40,000 mIU/ml and >40,000 mIU/ml respectively). HCGi and oestradiol were measured by enzyme immunoassays and bioactive HCG by the mouse Leydig cell bioassay. All results were analysed by analysis of variance and unpaired Student's t-test. There was a significant difference between bioactive to immunoreactive HCG ratios (b/i ratio) between the subgroups of low, intermediate and high HCGi concentrations. Lower b/i ratios were found when HCGi concentrations were high (HCG b/i mean +/- SEM: high subgroup, 0.33 +/- 0.07 versus low subgroup: 1.50 +/- 0.12; P < 0.0001). Furthermore, the b/i ratios were inversely correlated with oestradiol (P < 0.0001) and HCGi (P < 0.0001) concentrations but not with gestational age. There was no difference in the b/i ratios when comparing IUP with EP. It is concluded that, in first trimester pregnancies, there is a likely modulation of HCG bioactivity which is inversely correlated with HCGi and oestradiol concentration. The underlying mechanisms and their physiological relevance remain to be elucidated.

Distribution of the uncoupling protein 2 mRNA in the mouse brain

The present study was conducted to investigate the brain distribution of the recently cloned uncoupling protein 2 (UCP2). Northern blot analyses were first carried out to confirm the presence of UCP2 in the brain. These analyses revealed the brain presence of UCP2 mRNA and the absence of the mRNAs encoding uncoupling protein 1 and uncoupling protein 3. They also demonstrate that UCP2 mRNA expression was abundant in the hypothalamus and not affected by cold acclimation. In situ hybridization histochemistry was used to determine the brain distribution of the mRNA encoding UCP2. A markedly intense hybridization signal was found in the hypothalamus, the ventral septal region, the caudal hindbrain (medulla), the ventricular region, and the cerebellum. A very highly intense hybridization signal was apparent in the suprachiasmatic nucleus, the medial parvicellular part of the paraventricular hypothalamic nucleus, the arcuate nucleus, the dorsal motor nucleus of the vagus nerve, and the choroid plexus. The specifically localized expression of UCP2 mRNA suggests that this mRNA has a neuronal localization. Neuronal expression was particularly manifest in the nucleus of the horizontal limb of the diagonal band, the submedius thalamic nucleus and the dorsal motor nucleus of the vagus nerve, where agglomerations of the silver grains delineated individual cells. The role played by UCP2 in the brain has yet to be fully described, but the pattern of distribution of the transcript suggests that this mitochondrial protein is part of neuronal circuitries controlling neuroendocrine functions, autonomic responses, and the general arousal of the brain. Given the involvement of the proteins from the uncoupling protein's family in the uncoupling of cellular respiration, it can be argued that UCP2 contributes to the metabolic rate and thermoregulation of these circuitries. In addition, by promoting oxygen consumption in the brain, UCP2 could control the production of reactive oxygen species and thereby influence the process of neural degeneration.

Effects of leptin on corticotropin-releasing factor (CRF) synthesis and CRF neuron activation in the paraventricular hypothalamic nucleus of obese (ob/ob) mice

The effects of leptin on the levels of CRF messenger RNA (mRNA) in the paraventricular hypothalamic nucleus (PVN), on the activation of the PVN CRF cells, and on the plasma levels of corticosterone were investigated in lean (+/?) and obese (ob/ob) C57BL/6J male mice. Murine leptin was s.c. infused using osmotic minipumps. The treatment period extended to 7 days, and the daily dose of leptin delivered was 100 microg/kg. The mice were killed either in a fed state or following 24 h of total food deprivation. The starvation paradigm was employed to enhance the activity of the hypothalamic-pituitary-adrenal axis in obese mice. In situ hybridization histochemistry was performed to determine the PVN levels of CRF mRNA and the arcuate nucleus levels of neuropeptide Y mRNA. The activity of the PVN CRF cells was estimated from the number of PVN cells colocalizing CRF mRNA and the protein Fos. Leptin led to a reduction in body weight gain and fat deposition. These effects were seen in both +/? and ob/ob mice and were observed to be particularly striking in obese mutants, in which leptin also caused an important reduction in food intake. Leptin also was found to affect plasma levels of corticosterone. It lowered the high corticosterone levels of obese mutants, an effect that appeared more evident in food-deprived than in fed mice. Finally, leptin prevented the induction of CRF synthesis in the PVN and the activation of the PVN CRF neurons observed in food-deprived ob/ob mice and hindered the elevation of arcuate nucleus neuropeptide Y synthesis in ob/ob mice. Together these results suggest a role for leptin in the excessive response of the hypophysiotropic CRF system of the ob/ob mouse.

Ovariectomy and estradiol treatment affect the dopamine transporter and its gene expression in the rat brain

The impact of gonadal hormone withdrawal and estrogen therapy was investigated on the rat dopamine transporter (DAT). Short-term ovariectomized (ST-OVX, 2 weeks) and long-term ovariectomized (LT-OVX, 3 months) rats were treated or not with 17beta-estradiol (E2) for 2 weeks. DAT mRNA expression was measured by in situ hybridization in the substantia nigra pars compacta (SNc) for the nigrostriatal pathway and the ventral tegmental area (VTA) for the mesolimbic pathway whereas DAT levels were assessed by [3H]GBR-12935 autoradiography, respectively, in the striatum and the nucleus accumbens. Ovariectomy produced a time-dependent decrease of the DAT density in the striatum and the nucleus accumbens and the E2 treatment did not significantly restore these DAT levels. Neither ST-OVX nor E2 treatment of the ST-OVX animals altered the DAT mRNA expression in the SNc and the VTA. However, LT-OVX animals showed increased DAT mRNA levels in these regions. E2 treatment of LT-OVX animals partially restored DAT mRNA levels in the SNc and left these levels unchanged in the VTA. These opposite variations induced by OVX on the DAT density and their mRNA levels suggest the involvement of non-genomic mechanisms, such as post-transcriptional events and/or membrane effects. Altered neurotransmission following gonadal hormone withdrawal may contribute to CNS disorders occurring at menopause in predisposed women. Ovariectomized rats constitute a useful model to study the changes in neurotransmitters balance occurring after menopause.

Expression of corticotropin-releasing factor and its receptors in the brain of lean and obese Zucker rats

Expression of CRF messenger RNA (mRNA) and heteronuclear RNA (hnRNA) as well as the mRNAs encoding the CRF receptors of type 1 (CRF1R) and type 2 alpha (CFR2R) in the brain has been investigated in lean (Fa/?) and obese (fa/fa) Zucker rats. Exonic and intronic in situ hybridization histochemistry was employed to measure the mRNA and hnRNA levels in rats killed before (resting state), during, and 120 min after a treadmill running session. The resting expression of CRF hnRNA in the hypothalamic paraventricular nucleus (PVN) of obese rats was minimal and comparable to that of lean rats. However, during treadmill running, this expression was higher in obese than in lean rats. In obese rats, the transcription of the CRF1R mRNA in the PVN was high under resting conditions, dropped considerably during running, and rose again to elevated levels 120 min after the treadmill session. In lean rats, CRF1R mRNA in the PVN was minimal before and during running, but rose to a value similar to that in obese rats 120 min after running. In the PVN of obese rats, expression of the CRF1R gene measured during resting conditions was comparable to the level seen after running and proved to be dependent upon the feeding state of the rats. Expression of the CRF2R transcript was reduced in the ventromedial nucleus of the hypothalamus (VMH) of the obese rat. Plasma ACTH concentrations during treadmill running were lower in obese than in lean animals. Basal and postrunning levels of circulating corticosterone were higher in fa/fa than in Fa/? rats. However, there was no difference in corticosterone levels between lean and obese animals during running. The present results provide evidence for differences between lean and obese rats in the expression of CRF and its receptor within selective hypothalamic nuclei. Given the anorectic and thermogenic properties of CRF and the roles of PVN and VMH in the regulation of energy balance, it can be argued that the observed alterations in the biosynthesis of CRF and its receptors within the PVN and VMH might be related to the development of obesity.

Comparison of antimicrobial susceptibilities of Corynebacterium species by broth microdilution and disk diffusion methods

Corynebacterium species are increasingly being implicated in foreign-body infections and in immunocompromised-host infections. However, there are no specific recommendations on the method or the criteria to use in order to determine the in vitro activities of the antibiotics commonly used to treat Corynebacterium infections. The first aim of our study was to compare the susceptibilities of various species of Corynebacterium to vancomycin, erythromycin, and penicillin by using a broth microdilution method and a disk diffusion method. Second, the activity of penicillin against our isolates was assessed by using the interpretative criteria recommended by the National Committee for Clinical Laboratory Standards for the determination of the susceptibility of streptococci and Listeria monocytogenes to penicillin. Overall, 100% of the isolates were susceptible to vancomycin, while considerable variations in the activities of erythromycin and penicillin were noted for the different species tested, including the non-Corynebacterium jeikeium species. A good correlation in the susceptibilities of vancomycin and erythromycin between the disk diffusion and the microdilution methods was observed. However, a 5% rate of major or very major errors was detected with the Listeria criteria, while a high rate of minor errors (18%) was noted when the streptococcus criteria were used. Our findings indicate considerable variations in the activities of erythromycin and penicillin against the various species of Corynebacterium. Because of the absence of definite recommendations, important discrepancies were observed between the methods and the interpretations of the penicillin activity.

Elevations of nucleus accumbens dopamine and DOPAC levels during intravenous heroin self-administration

Extracellular dopamine and DOPAC (3,4-dihydroxyphenylacetic acid) levels in nucleus accumbens were sampled by microdialysis and quantified with high-performance liquid chromatography during intravenous heroin self-administration sessions in rats. Dopamine levels in 10 and 20 min samples were elevated following the first injection of each session, reaching a plateau of elevation within the first two or three injections and falling back toward baseline only when drug access was terminated. Elevations were in the range of 150-300% when unit dosages of 0.05-0.2 mg/kg were given. Increasing the work requirement from FR-1 to FR-10 did not appear to alter the degree of elevation of dopamine levels, and dopamine levels fell during extinction while lever-pressing rates increased 20-fold. While animals compensated for unit dose changes between 0.05 and 0.2 mg/kg/injection, adjusting their response rate such that the same hourly drug intake and the same asymptotic dopamine levels were maintained across these conditions, at 0.4 mg/kg/injection hourly drug intake and asymptotic dopamine levels were elevated beyond the levels sustained by the lower doses. These findings confirm that self-administered doses of intravenous heroin are sufficient to activate the mesolimbic dopamine system and suggest that significant heroin "craving" can emerge when dopamine levels are still moderately elevated, long before the development of dopamine depletion associated with opiate withdrawal.

Brain dopamine transporter: gender differences and effect of chronic haloperidol

Gender differences and the effect of chronic haloperidol on the rat brain dopamine transporter is reported. The density of striatal dopamine transporter sites labelled with [3H]GBR 12935, and of substantia nigra dopamine transporter mRNA measured by in situ hybridization were higher in female compared to male rats whereas striatal D2 specific binding labelled with [3H]spiperone was not significantly higher. Daily haloperidol treatment (1 mg/kg, i.p.) for 21 days increased striatal [3H]spiperone specific binding but left unchanged striatal [3H]GBR 12935 binding density and affinity as well as substantia nigra dopamine transporter mRNA levels. A reduce clearance rate of dopamine in the striatum after acute and chronic haloperidol was previously reported; the present results indicate that this may occur without changes in the sites of dopamine transport or in gene expression of this transporter.

Atypical neuroleptic-like behavioral effects of neurotensin

To better characterize the neuroleptic-like properties of neurotensin, the dose-related effects of the peptide on the following behavioral phenomena were examined: a) the yawning-penile erection syndrome induced by small doses of the dopamine agonists apomorphine and N-propylnorapomorphine (NPA); b) yawning produced by the anticholinesterase physostigmine, and c) stereotyped climbing and sniffing produced by a larger dose of apomorphine. Several doses of the peptide were injected intraventricularly 30 min prior to drug administration. Results indicate that neurotensin markedly decreased yawning and penile erections produced by both apomorphine and NPA. These effects were seen with relatively small doses (0.9-3.75 micrograms). Neurotensin also potently decreased physostigmine-induced yawning with the initial inhibitory effect seen with 50 ng of the peptide. Apomorphine-induced climbing was significantly attenuated with 30.0 and 60.0 micrograms neurotensin, whereas stereotyped sniffing was unaffected, even by doses as large as 120.0 micrograms. These findings suggest that neurotensin might antagonize dopamine autoreceptors and indicate that the peptide possess central anticholinergic activity. Furthermore, these results lend support to the hypothesis that neurotensin's profile of central actions resemble that of atypical neuroleptics.

Muscarinic antagonists attenuate neurotensin-stimulated accumbens and striatal dopamine metabolism

The effect of scopolamine and atropine upon the increase in extracellular 3,4-dihydroxyphenylacetic acid induced by central injection of neurotensin was examined in the nucleus accumbens and the striatum of anaesthetized rats using in vivo differential pulse voltammetry with carbon fibre electrodes. Scopolamine (1 and 3 mg/kg, i.p.) and atropine (20 micrograms, i.c.v.) did not alter the 3,4-dihydroxyphenylacetic acid level in the nucleus accumbens or the striatum, measured for 60 min after administration. Neurotensin (10 micrograms, i.c.v.) increased the 3,4-dihydroxyphenylacetic acid peak height in both regions. Pretreatment with scopolamine (1 mg/kg) 15 min before neurotensin injection blocked the increase in extracellular 3,4-dihydroxyphenylacetic acid in the striatum but not in the nucleus accumbens whilst scopolamine (3 mg/kg) partially attenuated the effect of neurotensin in the nucleus accumbens and blocked the increase in 3,4-dihydroxyphenylacetic acid in the striatum. Atropine partially attenuated the effect produced by neurotensin in the nucleus accumbens and blocked the increase in 3,4-dihydroxyphenylacetic acid induced by the peptide in the striatum. However, the increase in extracellular 3,4-dihydroxyphenylacetic acid induced by haloperidol (1 mg/kg, s.c.) was not altered by scopolamine (1 mg/kg) or atropine. Also, the increase in dopamine metabolism in the nucleus accumbens and the striatum after centrally injected haloperidol (10 micrograms, i.c.v.) was not altered by atropine (20 micrograms, i.c.v.). Together, the results demonstrate a functional interaction between muscarinic antagonists and neurotensin on in vivo dopamine metabolism in the nucleus accumbens and the striatum but with a greater effect in the latter region.

Differential effects of amfonelic acid on the haloperidol- and clozapine-induced increase in extracellular dopac in the nucleus accumbens and the striatum

This study compares the effects of the nonamphetamine stimulant amfonelic acid on the increase in extracellular 3,4-dihydroxyphenylacetic acid (DOPAC) induced by haloperidol and clozapine in the nucleus accumbens and the striatum of anaesthetized rats. DOPAC was simultaneously recorded in both regions using differential pulse voltammetry with electrically pretreated carbon fibre electrodes. Amfonelic acid (2.5 mg/kg s.c.) did not alter basal striatal DOPAC but produced a significant reduction in extracellular DOPAC in the nucleus accumbens. Haloperidol (1 mg/kg s.c.) increased extracellular DOPAC in both regions. When amfonelic acid was injected 5 min before haloperidol, the increase in DOPAC was potentiated in both the nucleus accumbens and the striatum but with a greater effect in the striatum. Clozapine (30 mg/kg i.p.) increased extracellular DOPAC in both regions, an effect partially attenuated by amfonelic acid in both regions but to a greater extent in the striatum. When ritanserin (5 mg/kg i.p.), a serotonergic antagonist (5-HT-2), was co-administered with haloperidol, the potentiation by amfonelic acid of the increase in extracellular DOPAC induced by haloperidol was attenuated in both the nucleus accumbens and the striatum. The present results confirm that amfonelic acid can be used to discriminate neurochemically between haloperidol and clozapine in vivo. The effects of amfonelic acid on the neuroleptic-induced changes in extracellular DOPAC were greater in the striatum than the nucleus accumbens. These results further demonstrate that both neuroleptics increase dopamine metabolism in the two brain regions but by different mechanisms, supporting the view that the regulation of dopamine metabolism differs in the two regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscarinic antagonists attenuate the increase in accumbens and striatum dopamine metabolism produced by clozapine but not by haloperidol

1. The effect of the muscarinic antagonists, scopolamine and atropine, were examined on the increase in extracellular 3,4-dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens and the striatum induced by haloperidol and clozapine by use of in vivo differential pulse voltammetry with carbon fibre electrodes in anaesthetized rats. 2. Animals received saline (1 ml kg-1, s.c.), scopolamine (1 mg kg-1, o.p.) or atropine (20 micrograms, i.c.v.) followed 15 min later by saline (10 microliters, i.c.v.), haloperidol (1 mg kg-1, s.c.) or clozapine (30 mg kg-1, i.p.) and extracellular DOPAC was simultaneously recorded in the nucleus accumbens and the striatum every 5 min for 60 min after drug administration. 3. Scopolamine or atropine alone had no effect on the DOPAC peak height but attenuated the increase in extracellular DOPAC induced by clozapine in both brain regions. Neither scopolamine nor atropine altered the haloperidol-induced increase in accumbens or striatal extracellular DOPAC. 4. The present results demonstrate that muscarinic antagonists attenuate the increase in accumbens and striatal dopamine metabolism in vivo produced by the atypical neuroleptic clozapine but not the haloperidol-induced increase in dopamine metabolism. The results indicate that central muscarinic receptors are involved in the actions on dopaminergic function of clozapine but not haloperidol.

Posterior hypothalamic receptors involved in the cardiovascular changes elicited by electrical stimulation of the rostral ventrolateral medulla

The posterior hypothalamic receptors involved in the cardiovascular responses to electrical stimulation of the rostral ventrolateral medulla were investigated in urethane-anaesthetized rats. Electrical stimulation of the rostral ventrolateral medulla produced a significant increase in systolic blood pressure. This response was significantly attenuated by the prior administration of d,l-propranolol (20 micrograms), clonidine (8 micrograms), atropine (8 micrograms) or methysergide (10 micrograms) into the posterior hypothalamus, but not by cimetidine (11 micrograms), chlorpheniramine (12 micrograms), naloxone (10 micrograms) or a vasopressin V1 antagonist (100 ng). The effect of clonidine (8 micrograms) on the pressor response to stimulation of the rostral ventrolateral medulla was antagonized by idazoxan (66 micrograms). These results confirm that the cardiovascular changes elicited by stimulation of the rostral ventrolateral medulla area are, in part, centrally modulated by alpha 2 and beta-adrenoceptors in the posterior hypothalamus which exert respectively, inhibitory and stimulatory effect. Furthermore the results indicate the involvement of posterior hypothalamic cholinergic and serotonergic receptors in the pressor response produced by stimulation of the rostral ventrolateral medulla.

Neuropeptides can interfere with the recording properties of voltammetric carbon fibre electrodes

The effects of neuropeptides on the recording properties of carbon fibre micro-electrodes used with differential pulse voltammetry were examined both in vitro and in vivo. The in vitro voltammetric signal recorded in a solution containing 3,4-dihydroxyphenylacetic acid (10(-4) M) was attenuated after the addition of thyrotropin releasing hormone, neuromedin N and neurotensin (10(-5) M). The administration of neurotensin (1 or 3 micrograms/microliters) into the nucleus accumbens adjacent to the carbon fibre electrode produced a decrease in the extracellular 3,4-dihydroxyphenylacetic acid peak. However, evidence was obtained that peptides alter the recording properties of the microelectrodes when present at sufficient concentrations and such an effect may explain the result obtained in vivo. In contrast, neurotensin administered into the ventral tegmental area increased the 3,4-dihydroxyphenylacetic acid peak in the nucleus accumbens as previously reported. Thus, attenuation of the voltammetric signal was caused by an effect of the peptide on the recording properties of the electrode rather than real diminution of the free oxidisable amine around the electrode. Caution should be taken when investigating the effects of peptides on extracellular amines or their metabolites using in vivo voltammetry with carbon fibre electrodes if the peptides are administered in high concentrations close to the electrode.

Use of amfonelic acid to discriminate between classical and atypical neuroleptics and neurotensin: an in vivo voltammetric study

Previous ex vivo studies have shown that the non-amphetamine stimulant amfonelic acid potentiates the increase in DOPAC induced by classical but not by atypical neuroleptics. In the present study, we have demonstrated that this neurochemical model can be used to discriminate typical from atypical neuroleptics in vivo using differential pulse voltammetry with carbon fibre electrodes. The study also compared the effect of intracerebroventricular (i.c.v.) administration of neurotensin, on extracellular striatal DOPAC following amfonelic acid, with the effects of both classical and atypical neuroleptics. Saline or amfonelic acid (2.5 mg/kg s.c.) were administered; followed 5 min later by the classical neuroleptics haloperidol, perphenazine, or the atypical neuroleptics clozapine, thioridazine, or by neurotensin. After drug administration extracellular striatal DOPAC was recorded every 5 min for 90 min. Amfonelic acid did not alter basal striatal DOPAC but potentiated the increase in DOPAC induced by haloperidol (1.0 and 0.05 mg/kg s.c.) and perphenazine (10 mg/kg s.c.). Both clozapine (30 mg/kg i.p.) and thioridazine (20 mg/kg s.c.) increased extracellular DOPAC, but pretreatment with amfonelic acid prevented the increase in DOPAC produced by both drugs. Neurotensin (10 micrograms, i.c.v.), in a similar manner to the atypical neuroleptics, increased extracellular DOPAC in the striatum and the effect was prevented by amfonelic acid. The present study demonstrates that pretreatment with amfonelic acid is a valuable tool to discriminate between classical and atypical neuroleptics in vivo. The results also indicate that neurotensin in the presence of amfonelic acid has a profile similar to the atypical neuroleptics.

Hypokinesia, rigidity, and tremor induced by hypothalamic 6-OHDA lesions in the rat

Bilateral administration of 6-hydroxydopamine in the medial fore-brain bundle at the level of the posterolateral hypothalamus in rats resulted in hypokinesia, muscular rigidity and tremor as determined by various behavioral assessment procedures. These neurological signs were accompanied by marked decreases in the concentrations of dopamine and its main metabolites dihydroxyphenylacetic acid and homovanillic acid in both striatum and nucleus accumbens. Administration of apomorphine (1 mg/kg) or L-Dopa (60 mg/kg) reversed or totally abolished the hypokinesia, rigidity and tremor in lesioned animals. Together, the present findings demonstrate that bilateral intrahypothalamic administration of 6-OHDA results in the appearance of the three cardinal symptoms of Parkinson's disease in rats. This model should prove to be valuable for both the study of the neuropathological processes underlying the neurological signs of this disease and the screening of potential antiparkinson agents.

Neurobehavioral profile of neuropeptide Y

In order to better delineate the profile of central actions of neuropeptide Y (NPY), the effects of intracerebroventricular administration of several doses (2.5-20 micrograms) of the peptide on spontaneous activity, muscular tone, body temperature, food intake, nociception and cataleptic manifestations were examined in rats. Results indicate that, starting at 5 micrograms. NPY significantly decreased motor activity of animals in a dose-related fashion. NPY also significantly lowered body temperature of animals. The hypothermic effect was obtained following injections of 10.0 and 20.0 micrograms of the peptide. Administration of the same two doses of NPY resulted in significant increases in food intake, muscular tone and induced a significant catalepsy in animals. On the other hand, nociceptive response times of animals in the hot plate test were not affected by any of the NPY doses tested. Together, these results indicate that the profile of NPY's neurobehavioral actions is more complex than previously reported and suggest that the peptide might be implicated functionally in a variety of neurophysiological processes.

Neurotensin selectively antagonizes apomorphine-induced stereotyped climbing

In order to better characterize the neuroleptic properties of neurotensin, the dose-related effects of the peptide on stereotyped climbing, sniffing and licking induced by 0.6 mg/kg apomorphine were examined. The following doses of the peptide were injected intraventricularly 30 min prior to apomorphine administration: 0.9, 3.75, 30.0 and 60 micrograms. Results indicate that, whereas oro-facial stereotypies remained unaffected by the peptide, stereotyped climbing was significantly decreased with the two largest doses of neurotensin. These findings indicate that the profile of neurotensin's neurobehavioral effects is more akin to that of atypical than typical neuroleptics.

Neurobehavioral evidence for kappa agonist activity of the morphinan derivative 14-beta-methyl 8-oxacyclorphan [BC (3016)]

The purpose of the present study was to determine if the in vivo neurobehavioral effects of the morphinan 14-beta-methyl 8-oxacyclorphan, [BC (3016)], would reflect the kappa agonist activity found in our previous in vitro studies. The effects of intracisternal administration of various doses (10-80 micrograms) of BC (3016) on body temperature, muscle rigidity, nociception of thermal, chemical and mechanical stimuli as well as its ability to induce catalepsy were examined. The effects of intrathecal administration of the same doses of the compound on reactivity of animals to a thermal stimulus were also assessed. Finally, the ability of BC (3016) to antagonize well known neurobehavioral effects of morphine was investigated. Results indicate that the analgesic properties of BC (3016) resemble those of typical kappa agonists: Intracisternal administration of the drug failed to affect nociception to an aversive thermal stimulus but markedly reduced the reactivity of animals subjected to noxious chemical or mechanical stimuli. On the other hand, intrathecal administration of BC (3016) significantly attenuated nociception of animals to a thermal stimulus. The in vivo neurobehavioral effects of BC (3016) appear to be kappa selective since the drug did not decrease body temperature, increase muscular tone or induce catalepsy, three effects generally attributed to mu agonists. Furthermore, BC (3016) antagonized the immobility, trunk rigidity, catalepsy and analgesia induced by morphine. In summary, the present results reveal that BC (3016) displays a profile of neurobehavioral effects similar to that of well known kappa agonists.

Antiparkinson-like effects of neurotensin in 6-hydroxydopamine lesioned rats

The aim of the present study was to examine the effects of neurotensin in an animal model of Parkinson's disease (PD). Bilateral administration of 6-OHDA in the medial forebrain bundle at the level of the posterolateral hypothalamus of rats resulted in the appearance of the 3 principal neurological signs of PD: hypokinesia, rigidity and tremor. These symptoms were accompanied by severe losses of dopamine and its main metabolites in terminal regions of well-known dopamine pathways. Norepinephrine concentrations were also decreased in several regions but to a lesser extent than dopamine. Intracerebroventricular administration of neurotensin, in doses ranging from 7.5 to 120.0 micrograms, resulted in dose related attenuations of both muscular rigidity and tremors of animals. However, hypokinesia, defined as decreased motor activity was not significantly affected by the peptide. Administration of 120.0 micrograms of [Ala]NT, an inactive analogue of neurotensin, failed to alter any of the 3 neurological signs. Together, these results reveal selective antiparkinson-like effects of neurotensin in an animal model. The theoretical significance of these findings is discussed.

Neurotensin causes a greater increase in the metabolism of dopamine in the accumbens than in the striatum in vivo

Differential pulse voltammetry with carbon fibre electrodes was used to study the effect of central administration of neurotensin on the extracellular level of 3,4-dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens and the striatum in anaesthetised rats. Intracerebroventricular injection of neurotensin (10 micrograms) increased the peak height for DOPAC 20 min after administration in the nucleus accumbens but only after 40 min in the striatum. The maximum increase was similar in both regions, with 30% and 27% above the pre-injection basal level, respectively. Neurotensin (1 micrograms) however increased the extracellular level of DOPAC in the nucleus accumbens alone. Neurotensin (0.1, 1.0 and 3.0 micrograms/0.5 microliter), injected into the ventral tegmental area, induced a potent and long-lasting elevation of the peak height for DOPAC in the nucleus accumbens, while the same doses in the substantia nigra produced effects on the metabolism of dopamine in the striatum of smaller amplitude and shorter duration. The maximum effect of each dose was about 2.5 times greater in the mesolimbic, compared to the nigrostriatal system. Amphetamine (2 mg/kg, s.c.) decreased the extracellular level of DOPAC with a similar magnitude, both in the nucleus accumbens (52%) and the striatum (47%). Intracerebroventricular administration of neurotensin (1 micrograms), 5 min after amphetamine, did not alter the effect of amphetamine on the extracellular level of DOPAC either in the nucleus accumbens or the striatum. However, neurotensin (10 micrograms) partially reversed the effect of amphetamine in the nucleus accumbens and had a similar but smaller and delayed effect in the striatum. The results from the present study, together with previous neurobehavioural studies, suggest that neurotensin has a relatively selective action on the mesolimbic dopaminergic system in the rat.

Structure-activity studies of neurotensin on muscular rigidity and tremors induced by 6-hydroxydopamine lesions in the posterolateral hypothalamus of the rat

It has previously been reported that intracerebroventricular administration of neurotensin (30 micrograms) reduced muscular rigidity and tremors, induced by a neurochemical lesion with 6-hydroxydopamine in the posterolateral hypothalamus of rats. In the present study, the effects of two fragments (NT1-10 and NT8-13) and two analogues ([D-Tyr11]-NT and [Ala11]-NT) of neurotensin on the grasping time (index of muscle rigidity) and tremors in 6-hydroxydopamine-lesioned rats are reported. Intracerebroventricular administration with 120 micrograms of NT1-10 and [Ala11]-NT had no effect on the muscle rigidity and tremors induced by the neurochemical lesion. The administration of NT8-13 60 micrograms) significantly attenuated both behavioural responses. The analogue [D-Tyr11]-NT produced a much greater attenuation of the muscle rigidity and tremors. The dose of 1.8 micrograms of [D-Tyr11]-NT significantly reduced the grasping time, while the number of tremors was attenuated with the threshold dose of 0.9 micrograms. Together, these results suggest that the effects of neurotensin on muscle rigidity and tremors, induced by pretreatment with 6-hydroxydopamine injected into the posterolateral hypothalamus, were not caused by non-specific effects but largely depended on the carboxy terminal of the peptide. The tyrosine residue in position 11 of the molecule plays a critical role in the action of neurotensin, as shown with the high potency and duration of action of the analogue [D-Tyr11]-NT. As previously suggested, the greater effect with [D-Tyr11]-NT may be due to greater resistance of the analogue to enzymatic degradation because of the incorporation of the D-Tyr amino acid, in position 11 of neurotensin.

Mitoxantrone use in breast cancer patients with elevated bilirubin

To determine the safety and efficacy of mitoxantrone use in hyperbilirubinemic breast cancer patients, a prospectively determined dosage schedule was evaluated in a multi-center trial. Pretreatment bilirubin prospectively defined three groups: Controls (with normal bilirubin) and two Study groups (with either moderate or severe bilirubin increase). Bilirubin determined initial mitoxantrone dose as well: bilirubin less than 3.5 mg/dl, 14 mg/m2; and bilirubin greater than or equal to 3.5 mg/dl, 8 mg/m2. Mitoxantrone at 14 mg/m2 was well tolerated in patients with moderate hepatic dysfunction. Patients with severe hepatic dysfunction demonstrated a mixed toxicity picture, with performance status (ECOG level 3) defining a population with limiting myelosuppression and/or early death. The survival of Study patients with severe hepatic dysfunction (median 17 days) was significantly worse than both Control (p less than 0.01) and Study (p less than 0.05) patients with lower bilirubin. Entry performance status (ECOG level 0-2 versus level 3) profoundly influenced survival (median survival 222 days versus 25 days, respectively, p less than 0.0001). Objective responses were seen in patients with both normal and elevated bilirubin. Bilirubin reduction following mitoxantrone commonly occurred, representing at least an indicator of favorable prognosis. Recommendations for mitoxantrone use include: 1. Patients with moderate bilirubinemia tolerate 14 mg/m2 mitoxantrone with reasonable chance for benefit. 2. Patients with severe hepatic dysfunction and poor performance status should not be given mitoxantrone. A definitive recommendation regarding use of reduced 8 mg/m2 mitoxantrone in patients with severe hyperbilirubinemia and favorable performance status requires further study.

Phase I clinical and pharmacokinetic study of mitoxantrone given to patients by intraperitoneal administration

On the basis of its high degree of cytotoxicity against fresh human ovarian cancers and its relative lack of vesicant activity, mitoxantrone administered by the i.p. route was studied in a Phase I and pharmacokinetic trial. Thirty-three patients with good performance status and diagnoses of metastatic or recurrent ovarian (31 patients) and colon (two patients) cancers were treated with 12- to 38-mg/m2 doses, administered by the i.p. route every 4 wk for up to ten treatment courses. Mitoxantrone doses were escalated at 2- to 3-mg/m2 increments in groups of three to 11 patients. Thirty-eight mg/m2 (by i.p. dwell without removal) were considered the maximally tolerated dose in that, of eight treated patients, four experienced severe leukopenia and six experienced severe abdominal pain. Response to i.p. mitoxantrone was evaluable in 17 patients. None of seven patients with clinically measurable intraabdominal or pelvic tumor masses responded; however, in three (50%) of six patients with nonmeasurable disease, there was normalization of previously elevated serum CA-125 concentrations for 3, 17, and 24 mo. Additionally, two (50%) of four patients who underwent third-look laparotomies were found to have greater than 75% reductions in i.p. tumor masses with response lasting 24 and 25 mo. At 38 mg/m2, mitoxantrone was associated with a mean concentration.time product of 100 micrograms.h/ml in the i.p. space and of 0.071 micrograms.h/ml in plasma, yielding an i.p./plasma area under the curve ratio of 1408. We conclude that chemical peritonitis is the dose-limiting toxicity of i.p. administered mitoxantrone and that a dose of 23 mg/m2 every 3 to 4 wk should be used in future Phase II trials in ovarian cancer patients with minimal residual intraabdominal and pelvic disease following second-look laparotomy.

The effects of neurotensin and [D-Tyr11]-NT on the hyperactivity induced by intra-accumbens administration of a potent dopamine receptor agonist

The effects of neurotensin on the strong and persistent hyperactivity induced in rats by intra-accumbens administration of ADTN, a potent dopamine agonist, were examined. Neurotensin was administered intraventricularly as well as bilaterally into the accumbens. With both routes of administration neurotensin significantly decreased the hyperactivity produced by ADTN. However, important differences in doses required to produce this effect were noted between the two routes of administration. Whereas intraventricular injection of doses as small as 0.05 micrograms neurotensin was sufficient to reduce hyperactivity, bilateral intra-accumbens administration of at least 1.8 micrograms was required to replicate the effect. ADTN induced hyperactivity was also significantly decreased by intraventricular and intra-accumbens injections of the structural analog [D-Tyr11]-NT. In both routes of administration, the inhibitory action of the analog was more persistent than that observed with neurotensin. As was the case for neurotensin, intraventricular administration of [D-Tyr11]-NT was more potent than intra-accumbens injections. Finally, the results of a preliminary experiment indicate that neurotensin injected intraventricularly can also decrease hyperactivity elicited by intra-accumbens administration of dibutyryl cyclic AMP. Taken together, the results of the present study demonstrate that neurotensin can affect hyperactivity elicited by a strong and persistent activation of mesolimbic dopamine receptors or by stimulation of events beyond these receptors. The observed greater efficacy of intraventricularly administered neurotensin in decreasing ADTN induced hyperactivity suggests an action of the peptide on regions distant from the accumbens, probably on efferent outputs of mesolimbic stimulation.

Relationships between structure and duration of neurotensin's central action: emergence of long acting analogs

Relationships between structure and duration of neurotensin's central action were examined. Included in the study were analogs containing amino acid substitutions at purported enzymatic cleavage sites of neurotensin: the arg8-arg9, the Pro10-Tyr11, and the Tyr11-Ile12 peptide bonds. Peptides were administered in rats via the cerebro-ventricular route and the ensuing hypothermia was monitored repeatedly until the effect dissipated. Results indicate that substitutions of the Tyr11 residue of the neurotensin molecule with either Dopa, Trp, D-Trp, or D-Tyr yielded analogs displaying markedly increased durations of action. Substitutions at other sites did not alter the time course of neurotensin's hypothermic effect. The longest acting analog was [Dopa11]-NT. At a dose of 7.5 micrograms the hypothermia induced by this analog persisted for 660 min while the effect of a same dose of neurotensin endured for only 90 min after injection. No clear correlation was found between the relative potency of analogs and their duration of action. Taken together, the results confirm the predominant role of Tyr11 in the inactivation of neurotensin by the brain, but do not support the hypothesis that relative potencies of structural analogs are solely dependent on differing susceptibilities to enzymatic degradation.