Hypertension: variations in prevalence in the black population

Prevalence trends in hypertension in black men and women show an inversion at about ages 45 to 54 years. Incidence, mortality, and treatment of hypertension after age 35 can probably be related to this inversion. Incidence data are inconsistent and scanty. Morbidity data are incomplete and mostly unreliable. Mortality data partially explain the inversion. Long-term epidemiologic studies of hypertension in black elderly persons are needed to explain these variations in prevalence, which may have a beneficial impact on treatment and prognosis.

Ca2+-dependent facilitated shortening in isotonic contraction of trachealis muscle

We compared isotonic shortening with isometric force generation as a function of external Ca2+ in 166 tracheal smooth muscle (TSM) strips from 27 mongrel dogs in vitro. Concentration-response curves were generated with muscarinic stimulation (acetylcholine, ACh), alpha-adrenergic receptor activation (norepinephrine after beta-adrenoceptor blockade, NE), serotonin (5-HT), and KCl-substituted Krebs-Henseleit solution. The concentrations of 5-HT causing half-maximal shortening (ECS50, 1.54 +/- 0.14 X 10(-7) M) and half-maximal active isometric tension (ECT50, 1.72 +/- 0.30 X 10(-7) M) were similar (P = NS). Likewise, ECS50 (21.9 +/- 0.7 mM) and ECT50, (22.0 +/- 0.9 mM) were similar for KCl. In contrast, facilitated isotonic shortening (i.e., greater isotonic shortening for comparable degrees of force generation) was elicited with ACh and NE for all levels of force generation between 15 and 85% of maximum and for all concentrations of ACh from 3 X 10(-8) to 3 X 10(-5) M (P less than 0.05 for all points). Facilitated isotonic shortening also was elicited for all concentrations of NE from 10(-8) to 10(-6) M (P less than 0.05 for all points). Removal of Ca2+ from the perfusate substantially reduced the potency of ACh (P less than 0.001) and abolished differences between ECS50 (2.23 +/- 0.28 X 10(-5) M) and ECT50 (2.50 +/- 0.46 X 10(-5) M, P = NS). We demonstrate that for comparable degrees of force generation, muscarinic and alpha-adrenergic receptor activation cause greater isotonic shortening than KCl or 5-HT and that this facilitated shortening is associated with the concentration of external Ca2+.

The use of calcium channel blockade for the prevention of postoperative adhesion formation

Prevention of postoperative adhesion formation is an issue of fundamental concern to the reproductive surgeon. The disappointing results of current adjunctive regimens have prompted a search for more potent antiadhesion therapies. Administration of nifedipine hydrochloride, a prototypical calcium channel blocking agent, to hamsters receiving a standardized traumatic lesion of the left uterine horn significantly inhibited primary adhesion formation as compared to control animals. These preliminary results suggest that calcium channel blockade may have the potential to favorably influence events related to peritoneal repair; further study of these agents as surgical adjuvants in the treatment of chronic pelvic adhesive disease is indicated.

Dopamine receptor stimulation does not affect phosphoinositide hydrolysis in slices of rat striatum

The effect of dopamine receptor stimulation on the accumulation of labelled inositol phosphates in rat striatal slices under basal and stimulated conditions was examined following preincubation with [3H]inositol. Incubation of striatal slices with the selective D-1 agonist SKF 38393 or the selective D-2 agonist LY 171555 for 5 or 30 min did not affect the basal accumulation of labelled inositol mono-, bis-, tris-, and tetrakisphosphate. Resolution by HPLC of inositol trisphosphate into inositol-1,3,4-tris-phosphate and inositol-1,4,5-trisphosphate isomers revealed that under basal conditions dopamine did not influence the accumulation of inositol-1,4,5-trisphosphate. Depolarisation evoked by KCl, or addition of the muscarinic receptor agonist carbachol, produced a marked increase in the accumulation of labelled inositol phosphates in both the presence and absence of lithium. Addition of dopamine did not reduce the ability of KCl or carbachol to increase inositol phospholipid hydrolysis. In the presence of lithium, dopamine (100 microM) enhanced KCl-stimulated inositol phospholipid hydrolysis, but this effect appears to be mediated by alpha 1 adrenoceptors because it was blocked by prazosin. SKF 38393 (10 microM) or LY 171555 (10 microM) also did not affect carbachol-stimulated inositol phospholipid hydrolysis. These data, in contrast to recent reports, suggest that striatal dopamine receptors do not appear to be linked to inositol phospholipid hydrolysis.

Identification of the C5a des Arg cochemotaxin. Homology with vitamin D-binding protein (group-specific component globulin)

The chemotactic activity of human C5a des Arg is enhanced significantly by an anionic polypeptide (cochemotaxin) in normal human serum and plasma. The cochemotaxin attaches to sialic acid residues within the oligosaccharide chain of native C5a des Arg to form a complex with potent chemotactic activity for human PMN. We investigated the nature of the cochemotaxin and found that vitamin D-binding protein is the putative cochemotaxin. Vitamin D-binding protein enhanced the chemotactic activity of native C5a des Arg, but had no effect on the chemotactic activity of either native C5a or FMLP. Sialic acid prevented both enhancement by vitamin D-binding protein of the chemotactic activity of native C5a des Arg and formation of C5a des Arg-vitamin D-binding protein complexes, detected by molecular sieve chromatography. Furthermore, vitamin D-binding protein and cochemotaxin exhibited identical molecular weights, isoelectric points, antigenic reactivity, and amino acid composition.

Residual urine volumes in patients with spinal cord injury: measurement with a portable ultrasound instrument

Spinal cord injured (SCI) patients are often placed on an intermittent catheterization (IC) program during their initial rehabilitation in an effort to establish a catheter-free state. A noninvasive method to quantitatively determine residual urine volumes would decrease unnecessary catheterizations and be useful in the management of an IC program. This study was undertaken to determine if bladder volumes could be accurately determined in a group of SCI patients using a portable ultrasound scanner. Fifteen SCI patients underwent a total of 224 ultrasonic bladder volume determinations and 57 urethral catheterizations. Immediately prior to catheterization, two investigators alternately performed a total of four ultrasound readings on each patient using a hand-held portable instrument, the BVI 2000. The first ultrasound volume determination was comparable to the average ultrasound volume (r2 = 0.956). For catheterized volumes versus the initial ultrasound volume determination, r2 = 0.80. The average error was 18% for catheterized volumes within the range 50-700ml. Our results compare favorably with both real-time scanning using standard equipment and other portable instruments. The noninvasive nature, negligible risks, and reasonable estimates of volume warrant consideration of portable ultrasound scanning for the determination of bladder volumes in SCI patients.

Out-of-hospital cardiac arrest. Use of electrophysiologic testing in the prediction of long-term outcome

We examined the role of electrophysiologic testing in the prediction of long-term outcome in 166 survivors of out-of-hospital cardiac arrest not associated with acute myocardial infarction. Ventricular arrhythmias were inducible in 131 patients (79 percent) at base line and were suppressed by antiarrhythmic drugs or surgery (or both) in 91 of 127 (72 percent). During a median follow-up period of 21 months, cardiac arrest recurred in 29 patients: 11 (12 percent) of the 91 in whom inducible arrhythmias had been suppressed (including 5 patients in whom treatment had been discontinued), 12 (33 percent) of the 36 in whom inducible arrhythmias persisted, and 6 (17 percent) of the 35 in whom arrhythmias could not be induced at the initial electrophysiologic study. Cox survival analysis identified the following three variables as significant independent predictors of recurrent cardiac arrest: persistence of inducible ventricular arrhythmias (relative risk, 3.97 [95 percent confidence interval, 1.80 to 8.75], P = 0.0006), a left ventricular ejection fraction of 30 percent or less (relative risk, 2.60 [1.21 to 5.53], P = 0.0138), and the absence of cardiac surgery (relative risk, 4.20 [0.99 to 17.77], P = 0.0512). We conclude that electrophysiologic testing is useful in quantifying the subsequent risk of cardiac arrest among survivors of out-of-hospital cardiac arrest.

Endogenous dopamine functionally activates D-1 and D-2 receptors in striatum

Rat striatal slices incubated with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine at 1 mM were exposed to different concentrations (1-100 microM) of the catecholamine-releasing drug amphetamine. This produced both a concentration-dependent release of endogenous dopamine and accumulation of cyclic AMP in the slices. The cyclic AMP accumulation due to amphetamine was greatly increased when slices were coincubated with the selective dopamine D-2 antagonist (-)-sulpiride (30 microM), but the amphetamine-induced release of dopamine from the slices was the same in the presence or absence of (-)-sulpiride. Pretreatment of animals with reserpine (5 mg/kg s.c., 18 h before death) and in vitro incubation with alpha-methyl-p-tyrosine (50 microM for 90 min), respectively, reduced the ability of amphetamine (1-100 microM) [in the presence of 30 microM (-)-sulpiride] to induce release of dopamine and to elevate cyclic AMP accumulation in striatal slices. A similar reduction in amphetamine-induced dopamine release and cyclic AMP accumulation in striatal slices was observed 7 days following unilateral 6-OHDA lesions of the medial forebrain bundle of rats. These results suggest that amphetamine induces release of endogenous dopamine from the terminals of nigrostriatal dopamine neurones. Released dopamine is then able functionally and concomitantly to activate D-1 and D-2 receptors, seen as stimulation and inhibition of cyclic AMP accumulation, respectively.

Beyond the online catalog: developing an academic information system in the sciences

The online public access catalog consists essentially of a machine-readable database with network capabilities. Like other computer-based information systems, it may be continuously enhanced by the addition of new capabilities and databases. It may also become a gateway to other information networks. This paper reports the evolution of the Bibliographic Access and Control System (BACS) of Washington University in end-user searching, current awareness services, information management, and administrative functions. Ongoing research and development and the future of the online catalog are also discussed.

Neurochemical and behavioural evidence that dopamine D-2 receptors in striatum couple to the Ni regulatory protein and inhibition of cyclic AMP accumulation

The effects of intrastriatal pertussis toxin, which inactivates the regulatory protein Ni, were investigated in various models of striatal D-2 receptor function in the rat. Using a multiple injection technique unilateral intrastriatal injections of pertussis toxin induced, after a lag phase, ipsilateral postural asymmetries which intensified upon peripheral administration of apomorphine. Injections of pertussis toxin also partially reduced the ability of a selective D-2 agonist, RU 24926 [N-n-propyl di-beta (3-hydroxyphenyl)-ethylamine], to inhibit cyclic AMP accumulation due to a selective D-1 agonist SKF 38393 (2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine), whilst also reducing the affinity of dopamine for D-2 binding sites in striatal membranes from animals given prior intrastriatal injections of the toxin. Pertussis toxin also increased striatal dopamine metabolism, seen as a reduction in the dopamine: DOPAC (3,4-Dihydroxyphenylacetic acid) ratio, similar to that seen following intrastriatal injections of the selective D-2 antagonist (+/-)-sulpiride. These results suggest that pertussis toxin has dopamine D-2 antagonist-like properties in the rat striatum, consistent with the idea that striatal D-2 function may rely, in part at least, upon the regulatory protein Ni and adenylate cyclase inhibition.

Reality perceptions of television: a comparison of emotionally disturbed, learning disabled, and nonhandicapped children

The Stony Brook Videotest (SBV), a measure of reality perceptions of television programs and commercials, was administered to 38 emotionally disturbed (ED), 35 learning disabled (LD), and 159 nonhandicapped elementary school children. The ED and LD children scored significantly lower than the comparison group, indicating that ED and LD children are less able to distinguish between reality and fantasy on television. The clinical implications of these findings and possible remedial actions are discussed.

Dopamine D-2 receptors inhibit D-1 stimulated cyclic AMP accumulation in striatum but not limbic forebrain

The effect of dopamine D-2 receptor activation on dopamine D-1 stimulated cyclic AMP accumulation was investigated in slices of rat striatum and limbic forebrain (nucleus accumbens and tuberculum olfactorium). In striatal slices the dose-dependent increase in cyclic AMP accumulation due to dopamine (3-100 mumol/l) was enhanced by selective D-2 receptor blockade using (-)-sulpiride (30 mumol/l). In limbic slices the increase in cyclic AMP due to dopamine (3-50 mumol/l) was unaffected by selective D-2 receptor blockade. The enhancement of cyclic AMP accumulation due to the selective D-1 agonist SKF 38393 (2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; 1 mumol/l) in striatal slices was attenuated in the presence of the selective D-2 receptor agonist LY 171555 (quinpirole hydrochloride; 10 mumol/l). This attenuation was in turn blocked by (-)-sulpiride (10 mumol/l). In limbic slices LY 171555 (10 mumol/l) had no effect on SKF 38393 (1 mumol/l) stimulated cyclic AMP accumulation. Conversely muscarine receptor activation, using carbachol (10 mumol/l), attenuated D-1 stimulated cyclic AMP accumulation in both striatum and limbic forebrain. Dopamine D-2 or muscarine receptor stimulation in either striatal or limbic slices did not attenuate cyclic AMP accumulation due to VIP (vasoactive intestinal polypeptide; 0.5 mumol/l), isoprenaline (10 mumol/l) or 2-chloroadenosine (100 mumol/l). This suggests that in striatal slices, D-2 receptors mediate a selective inhibition of D-1 stimulated cyclic AMP accumulation, but that in the limbic forebrain D-2 receptors are unlikely to be coupled to D-1 receptor-linked adenylate cyclase. These data indicate a fundamental difference in the properties of D-2 receptor-effector coupling in these brain regions.

Comparison of changes in locomotor activity with striatal homovanillic acid and 3,4-dihydroxyphenylacetic acid concentrations following the bilateral intranigral injection of dopamine agonist drugs in rats

Bilateral injection of apomorphine (2.5 micrograms) into the substantia nigra zona reticulata of rats reduced both locomotor activity and striatal HVA and DOPAC concentrations. Bilateral injection of dopamine (10 micrograms) did not affect locomotor activity whereas a higher dose of dopamine (50 micrograms) enhanced locomotor activity. Striatal HVA and DOPAC concentrations were unchanged following injection of dopamine. Bilateral injection of (+/-)-3PPP (0.1 or 2.5 micrograms) into the zona reticulata of the substantia nigra did not alter locomotor activity while a higher dose (10 micrograms) enhanced locomotion. Injection of (+/-)-3PPP (0.1-10 micrograms) into the zona reticulata was without effect on striatal HVA or DOPAC concentrations. The bilateral manipulation of nigral dopaminergic neurotransmission alters motor activity and nigrostriatal dopamine turnover in conscious rats. However, the changes in motor activity are not necessarily related to altered nigrostriatal activity, suggesting the involvement of dopamine receptors located at non-dopaminergic sites within the substantia nigra.

Reproducibility of ventricular tachycardia suppression by antiarrhythmic drug therapy during serial electrophysiologic testing in coronary artery disease

The short-term reproducibility of pharmacologic suppression of ventricular tachycardia (VT) induced by programmed cardiac stimulation was tested in patients with coronary artery disease presenting with documented recurrent VT or ventricular fibrillation. Sixty-three consecutive patients in whom sustained VT (30 patients) or nonsustained VT (33 patients) was induced by programmed cardiac stimulation without antiarrhythmic drug treatment, and in whom at least 1 oral antiarrhythmic drug regimen suppressed the induced VT during serial electrophysiologic testing, were entered into the study. Programmed cardiac stimulation was repeated after a mean of 37 +/- 14 hours during the same antiarrhythmic drug regimen. No VT was induced in 59 of the 63 patients during the second study, resulting in a rate of 94% for short-term reproducibility of pharmacologic suppression of induced VT. Of the remaining 4 patients, programmed cardiac stimulation during the second drug study induced sustained VT in 1 patient and nonsustained VT in 3 patients. There was no significant difference in mean right ventricular effective refractory period and QT interval between the first and second drug study. Thus, in this selected population of patients, pharmacologic suppression of electrically induced VT is a reproducible phenomenon.

Specific inhibition of dopamine D-1-mediated cyclic AMP formation by dopamine D-2, muscarinic cholinergic, and opiate receptor stimulation in rat striatal slices

The ability of different receptors to mediate inhibition of cyclic AMP accumulation due to a variety of agonists was examined in rat striatal slices. In the presence of 1 mM 3-isobutyl-1-methylxanthine, dopamine D-2, muscarinic cholinergic, and opiate receptor stimulation by RU 24926, carbachol, and morphine (all at 10(-8)-10(-5) M), respectively, inhibited the increase in cyclic AMP accumulation in slices of rat striatum due to dopamine D-1 receptor stimulation by 1 microM SKF 38393. In contrast, these inhibitory agents were unable to reduce the ability of a number of other agonists, including isoprenaline, prostaglandin E1, 2-chloroadenosine, vasoactive intestinal polypeptide, and cholera toxin, to increase cyclic AMP levels in striatal slices. These results suggest that in rat striatum either dopamine D-2, muscarinic cholinergic, and opiate receptors are only functionally linked to dopamine D-1 receptors or that the D-1 and D-2 receptors linked to adenylate cyclase lie on the cells, distinct from other receptors capable of elevating striatal cyclic AMP levels.

The effect of adrenal demedullation on cardiovascular responses to environmental stimulation in conscious rats

Circulating plasma adrenaline has been implicated in the facilitation of neurogenic pressor responses and development of hypertension. Bilateral adrenal demedullation in rats did not affect body weight, urine output, urinary electrolyte (Na+, K+ and Cl-) excretion, nor plasma corticosterone concentration, indicating the selective nature of the demedullation procedure. Adrenal demedullation did induce significant reductions in adrenal catecholamine content, plasma adrenaline levels, resting blood pressure and heart rate in conscious rats, but did not affect alerting-induced increases in blood pressure. The adrenal medulla and circulating plasma adrenaline appear to contribute to the maintenance of resting cardiovascular parameters, but would not appear to be involved in nor facilitate the cardiovascular responses to environmental stimulation.

Mesolimbic dopamine function is not altered during continuous chronic treatment of rats with typical or atypical neuroleptic drugs

Rats were treated continuously for up to 20 months with either haloperidol (1.4-1.6 mg/kg/day), sulpiride (102-109 mg/kg/day) or clozapine (24-27 mg/kg/day). Bmax for specific mesolimbic binding of 3H-spiperone, 3H-N, n-propylnorapomorphine or 3H-piflutixol did not differ in tissue taken from animals treated for up to 12 months with haloperidol, sulpiride or clozapine by comparison to age-matched control rats. Mesolimbic dopamine (50 microM)-stimulated adenylate cyclase activity was not altered in any drug treatment group. Spontaneous locomotor activity was transiently decreased during treatment with haloperidol for 1 or 3 months, but not by chronic sulpiride or clozapine treatment. Locomotor activity was not consistently increased in any drug treatment group. After 20 months of continuous drug treatment, focal bilateral application of dopamine (12.5 or 25 micrograms) into the nucleus accumbens caused equivalent increases in locomotor activity in control rats and in animals receiving haloperidol, sulpiride or clozapine. These findings suggest that dopamine receptor blockade is not maintained in the mesolimbic area following chronic treatment with haloperidol, sulpiride or clozapine, and indicate that, under these conditions, clozapine and sulpiride may not act selectively on mesolimbic dopamine receptors.

The effects of dopamine and dopamine agonists on the release of 3H-GABA and 3H-5HT from rat nigral slices

Only high micromolar concentrations of dopamine and dopamine agonists altered spontaneous and KCl-evoked release of 3H-GABA and 3H-5HT from rat nigral slices in vitro. Apomorphine (100 microM) and dopamine (100 microM) enhanced the spontaneous release of 3H-5HT but the effect of dopamine was not reversed by haloperidol (1 microM). Both apomorphine (100 microM) and dopamine (100 microM) enhanced the KCl-evoked release of 3H-5HT but these effects were not reversed by haloperidol (1 microM). Apomorphine (10-250 microM) and dopamine (10-250 microM) inhibited 3H-5HT uptake into nigral synaptosomal preparations in a concentration-dependent manner. Accordingly, a major portion of the apparent effect of these drugs on 3H-5HT release may be due to inhibition of 3H-5HT uptake. Dopamine (100 and 1000 microM), amphetamine (100 microM), apomorphine (100 microM) and 2-amino-6,7-dihydroxytetralin (ADTN; 100 microM) were without effect on the spontaneous release of 3H-GABA from nigral slices. Apomorphine (100 microM) and ADTN (100 microM) reduced the KCl-evoked release of 3H-GABA from substantia nigra, an effect antagonized by haloperidol (1 microM). However, amphetamine (100 microM) and dopamine (100-1000 microM) were without effect on KCl-evoked 3H-GABA release. These results suggest that only high concentration of some dopamine agonists can modulate 3H-5HT and 3H-GABA release in substantia nigra. However, dopamine either had no effect, or its actions were not reversed by dopamine receptor blockade, so it appears unlikely that dendritic dopamine release will influence GABA and 5HT release in substantia nigra.

Determinants of the outcome of electrophysiologic study in patients with ventricular tachyarrhythmias

To determine those factors predictive of the ability to both initiate and suppress ventricular tachyarrhythmias during electrophysiologic study, the results of programmed cardiac stimulation were evaluated in 261 patients: 66 presenting with nonsustained ventricular tachycardia, 91 with sustained ventricular tachycardia and 104 with ventricular fibrillation. Multivariate logistic regression analysis revealed that the presenting arrhythmia was a potent and independent predictor of the ability to provoke ventricular arrhythmias at electrophysiologic study; a history of myocardial infarction and male sex were also significant independent predictors. Of patients presenting with sustained ventricular tachycardia, 89% (81 of 91) had inducible ventricular arrhythmias compared with 61 (40 of 66) and 66% (69 of 104) of patients with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Complete suppression of inducible arrhythmias could be achieved in only 52% (34 of 66) of patients with sustained ventricular tachycardia, compared with 73 (24 of 33) and 75% (46 of 61) of patients presenting with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Multivariate analysis showed that the major independent determinants of the ability to suppress inducible arrhythmias were the number of drug trials performed before electrophysiologic study (inversely correlated) and the nature of the induced arrhythmia. The nature of the presenting clinical arrhythmia is, therefore, a highly significant and independent predictor of the ability to induce ventricular arrhythmias during electrophysiologic testing and an important determinant of the ability to suppress induced arrhythmias in patients with spontaneous ventricular tachyarrhythmias.

Manual stimulation of reflex voiding after spinal cord injury

Thirty-four urodynamic studies were performed in 20 patients with spinal cord injury (SCI) to determine the most effective triggering mechanism for reflex voiding. The studies were performed at a time when the patient was normally scheduled for catheterization, which avoided stimulation of the detrusor and sphincter by bladder filling via a catheter. The three methods chosen were used in a random sequence. Suprapubic tapping and jabbing were equally effective in producing a rise in detrusor pressure, and the sphincter responses were almost identical. Cutaneous stimulation of the thigh rarely produced any change in detrusor and sphincter activity. When detrusor contractions were produced, a dyssynergic sphincter response prevented voiding in 46% of the studies; however, voiding always occurred when the sphincters were either coordinated or showed no change. Both tapping and jabbing were more effective as the time from injury increased, which reflects the natural recovery from spinal shock.

Evidence that [3H]dopamine is taken up and released from nondopaminergic nerve terminals in the rat substantia nigra in vitro

Potassium chloride (25 mM) and (+)-amphetamine (100 microM) both stimulated the release of radioactivity from slices of substantia nigra preincubated with [3H]3,4-dihydroxyphenylethylamine [( 3H]dopamine). Potassium chloride (25 mM) released radioactivity from slices of both zona compacta and zona reticulata. Prior 6-hydroxydopamine (6-OHDA) lesions of one nigrostriatal pathway did not reduce the spontaneous release of radioactivity, or the potassium chloride- or amphetamine-induced release of radioactivity from slices of nigra ipsilateral to the lesion after preincubation with [3H]dopamine. The accumulation of radioactivity following incubation of nigral slices from 6-OHDA-lesioned animals with [3H]dopamine was increased when compared to uptake into slices from intact tissue. In synaptosomal preparations of striatum, nomifensine but not desipramine or fluoxetine inhibited [3H]dopamine uptake. In contrast, nomifensine, desipramine, and fluoxetine all inhibited [3H]dopamine uptake in nigral synaptosomal preparations. Following 6-OHDA lesions of one nigrostriatal pathway the uptake of [3H]dopamine into nigral synaptosomal preparations was unchanged but uptake into striatal preparations was substantially decreased. In contrast, bilateral electrolesions of the dorsal and medial raphe nuclei reduced [3H]dopamine uptake into nigral preparations but not into striatal synaptosomes. The uptake of [3H]5-hydroxytryptamine ([3H]5-HT) into synaptosomal preparations of substantia nigra was abolished by fluoxetine and reduced by desipramine, but was unaffected by nomifensine. In contrast, fluoxetine, desipramine, and nomifensine all inhibited [3H]5-HT uptake into striatal synaptosomal preparations. Following 6-OHDA lesions of one nigro-striatal pathway the uptake of [3H]5-HT into nigral synaptosomal preparations was unchanged but uptake into striatal preparations was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of effect of intranigral administration of a dopamine analogue, (+/-)-3-(3-hydroxyphenyl)-N,n-propylpiperidine [(+/-)-3-PPP], on nigrostriatal dopamine neurones

Bilateral injection of apomorphine into the zona reticulata of substantia nigra in rats reduced locomotor activity and striatal dopamine (DA) turnover. In contrast, bilateral injection of (+/-)-3-(3-hydroxyphenyl)-N,n-propylpiperidine [(+/-)-3-PPP] into the zona reticulata (ZR) did not reduce locomotor activity and did not affect striatal DA turnover. A high dose of (+/-)-3-PPP increased locomotor activity. Unilateral injection of (+/-)-3-PPP, but not of apomorphine, into the ZR induced a brief period of contraversive rotation. (+/-)-3-PPP may not alter nigral DA autoreceptor function but may interact with DA receptors located on non-dopaminergic nigral neurones.

Biological properties of N4- and N1,N8-spermidine derivatives in cultured L1210 leukemia cells

Eleven novel spermidine (SPD) derivatives were synthesized as potential anticancer agents and evaluated for their ability to compete with [3H]SPD for cellular uptake, to inhibit cell growth, to affect polyamine biosynthesis, to suppress enzyme activity, and to substitute for SPD in supporting growth of cultured L1210 leukemia cells. The compounds included a series of N4-SPD derivatives (N4-methyl-SPD, N4-ethyl-SPD, N4-acetyl-SPD, N4-hexyl-SPD, N4-hexanoyl-SPD, N4-benzyl-SPD, and N4-benzoyl-SPD) and a series of N1,N8-SPD derivatives [N1,N8-bis(ethyl)-SPD, N1,N8-bis(acetyl)-SPD, N1,N8-bis(propyl)-SPD, and N1,N8-bis(propionyl)-SPD]. Uptake studies revealed N4-alkyl derivatives to be the most effective competitive inhibitors of [3H]SPD uptake (Ki, 26 to 43 microM) followed by N1,N8-alkyl derivatives (Ki, 71 to 115 microM), then N4-acyl derivatives (Ki, 115 to greater than 500 microM), and N1,N8-acyl derivatives (Ki, greater than 500 microM). The data indicate the relative importance of the terminal amines and of charge as determinants of cellular uptake. Of the 11 derivatives, only N4-hexyl-SPD, N1,N8-bis(ethyl)-SPD, and N1,N8-bis(propyl)-SPD demonstrated antiproliferative activity at 0.1 mM with 50%-inhibitory concentration values at 48 h of 30, 40, and 50 microM, respectively. In the case of the N1,N8-SPD derivatives, recovery from growth inhibition was enhanced considerably by exogenous SPD, suggesting involvement of polyamine depletion. At 10 to 30 microM, both N1,N8-bis(ethyl)-SPD and N1,N8-bis(propyl)-SPD (but not N4-hexyl-SPD) inhibited polyamine biosynthesis as indicated by significant reductions in polyamine pools and in biosynthetic enzyme activities. The more effective of the two, N1,N8-bis(ethyl)-SPD, depleted intracellular putrescine and SPD and reduced spermine by approximately 50% at 96 h and decreased ornithine and S-adenosylmethionine decarboxylase activities by 98 and 62%, respectively. Since neither derivative (at 5 mM) directly inhibited these enzymes from untreated cell extracts by significantly more than SPD itself, it is suspected that they act by regulating enzyme levels. As a measure of regulatory potential of the derivatives, ornithine decarboxylase was assayed in cells treated for 24 h and compared to the effects of 10 microM SPD which reduced the enzyme activity by 80%. None of the N4-SPD derivatives affected ornithine decarboxylase activity, while N1,N8-bis(ethyl)- and (propyl)-SPD were nearly as effective as SPD. Apparently, the central amine of the molecule is critical for regulatory function.(ABSTRACT TRUNCATED AT 400 WORDS)

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonism in the common marmoset

The administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (1-4 mg/kg i.p.) for 4 days induced dose-dependent parkinsonism in the common marmoset within 48 h. MPTP produced profound akinesia, rigidity of the trunk and limbs, postural abnormalities, loss of vocalization and, in some cases, postural tremor. In a single animal the administration of L-DOPA in conjunction with a peripheral decarboxylase inhibitor, reversed the parkinsonian symptoms. Subsequent biochemical analysis showed a profound loss of dopamine and [3H]dopamine uptake in the caudate-putamen, but no change in specific [3H]spiperone binding.

Effect of aspirin and dipyridamole on the patency of lower extremity bypass grafts

Recent clinical studies indicate that the use of aspirin and dipyridamole improves graft patency rates in patients with infrainguinal polytetrafluoroethylene (PTFE) grafts and aortocoronary vein grafts. We undertook a prospective, double-blind, randomized study to determine whether these drugs administered postoperatively to patients with PTFE or autologous vein infrainguinal bypasses would improve graft patency during the first 24 months after operation. Patients received either aspirin 325 mg and dipyridamole 75 mg or identical placebo tablets three times a day, taken orally. Patency rates were compared by computing standard life tables and comparing cumulative patency rates. One hundred patients with 102 grafts were studied. The cumulative patency rate at 24 months was not significantly different for the treatment (57%) versus control (67%) groups or for any subgroup. We conclude that aspirin and dipyridamole administered postoperatively in the doses used in this study do not improve the overall patency rates of vein or PTFE infrainguinal bypass grafts.

Is lactation a risk factor of IUD- and sterilization-related uterine perforation? A hypothesis

A recent article reported a high risk of IUD-related uterine perforation in lactating women in the U.S. This article prompted the authors to examine the large international datasets on IUDs and tubal sterilizations collected by Family Health International. The findings are somewhat suggestive of such a positive association in IUD users as well as in women undergoing laparoscopic or minilaparotomy sterilization. More definitive studies are urged.

Dopamine receptor binding sites in the rat superior colliculus

Following intravenous administration of [3H]spiperone or [3H]N,n-propylnorapomorphine (NPA) to rats, radioactivity derived from the ligands accumulated in the striatum and superior colliculus when compared with cerebellar levels. The accumulation of [3H]spiperone in both areas was prevented by intraperitoneal administration of (+)-butaclamol, haloperidol and sulpiride but not by (-)-butaclamol, cinanserin, propranolol or prazosin. The accumulation of [3H]NPA was prevented by administration of (+)-butaclamol, haloperidol and apomorphine but not by (-)-butaclamol. In in-vitro experiments, membrane preparations from the superior colliculus showed a small number of specific binding sites for both [3H]spiperone and [3H]NPA. The dissociation constant (KD) for [3H]NPA was not different from that for striatal preparations but that for [3H]spiperone was 10-fold higher. We conclude that dopamine receptors may be present within the superior colliculus.

Behavioural effects mediated by unilateral nigral dopamine receptor stimulation in the rat

Unilateral intranigral injections of dopamine in conscious rats pretreated with nialamide resulted in either ipsiversive or contraversive rotation depending upon the site of injection. Injection of dopamine (50 micrograms) into the zona compacta of the substantia nigra induced weak ipsiversive or mixed ipsiversive and contraversive rotation. Injection of dopamine (12.5-50.0 micrograms) into zona reticulata of substantia nigra induced only contraversive circling. Destruction of the ipsilateral medial forebrain bundle (MFB) using 6-hydroxydopamine (6-OHDA) abolished ipsiversive circling but enhanced contraversive circling produced by dopamine or apomorphine. The combination of a unilateral 6-OHDA lesion of MFB with a kainic acid or electrolesion of the ipsilateral strio-nigral and pallido-nigral pathways reduced contraversive circling to intranigral apomorphine (10 micrograms). Ipsiversive circling produced following intranigral injection of dopamine is dependent upon the integrity of ascending dopamine neurones. Contraversive rotation is independent of ascending dopamine pathways but is reliant upon afferent input to the substantia nigra from the striatum and/or globus pallidus.

Repeated administration of N-methyl-4-phenyl 1,2,5,6-tetrahydropyridine to rats is not toxic to striatal dopamine neurones

N-Methyl-4-phenyl-1,2,5,6-tetrahydropyridine ( MPTP ) (10 mg/kg/day i.p.) was administered to rats for 16 days, which were then observed for a further 9-11 days. MPTP administration did not alter spontaneous locomotor activity or amphetamine (2.5 mg/kg ip)-induced locomotion. Apomorphine (0.25 mg/kg sc) did not alter locomotion in control rats but increased activity in MPTP treated animals. The stereotyped response to apomorphine (0.25 mg/kg sc) and amphetamine (2.5 and 5.0 mg/kg ip) was unaltered by MPTP administration. The striatal content of dopamine, HVA and DOPAC was unaltered by MPTP intake. The uptake of [3H]dopamine and [3H] 5HT in striatal synpatosomes was not changed by MPTP . The results suggest that MPTP , in the dose used, is not toxic to nigro-striatal dopamine neurones in the rat. This contrasts with its neurotoxic actions in monkeys and man.

Induction of idiotope suppression in the anti-azophenylarsonate response of T-depleted A/J mice

The homologous, monoclonal antiidiotope, MB, induced idiotope suppression that was remarkably stable and could be transferred by B lymphocytes. Marked depletion of T cell function, confirmed by limiting diluting analysis, did not affect the ability of MB to suppress the corresponding idiotope. Suppression induced by MB appears to result from direct interaction with idiotope-positive B cells, without the intervention of idiotope-specific T suppressor cells.

Stimulation of presynaptic dopamine autoreceptors by 4-(2-di-n-propylaminoethyl) indole (DPAI)

The dopaminergic activity of 4-(2-di-n-propylaminoethyl)indole (DPAI) was investigated. In animal models for postsynaptic dopaminergic activity DPAI showed only very weak or no effects. In rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal tract, very weak contralateral turning behavior was induced in 4/6 rats. DPAI did not induce stereotyped behavior but caused a pronounced reduction in locomotor activity. In male rats pretreated with reserpine, DPAI lowered serum prolactin levels. Levels of homovanillic acid (HVA) were monitored in the striatum of the chloral hydrate anesthetized rat by means of in vivo voltammetry. DPAI administration reduced the faradaic peak corresponding to HVA. In rats pretreated with the decarboxylase inhibitor, NSD-1015, DPAI blocked the accumulation of dopa in response to gamma-butyrolactone. The results of this study indicate that DPAI possesses a high degree of selectivity for presynaptic dopamine autoreceptors, and little or no effect on postsynaptic dopamine receptors.

Adverse reactions during treatment with amiodarone hydrochloride

Amiodarone was administered to 80 patients with recurrent cardiac tachyarrhythmias previously resistant to drug treatment. Forty nine patients were treated for ventricular tachycardia or fibrillation and 31 for supra-ventricular arrhythmias. The mean (range six days to 51 months), permitting a total of 100 patient years of observation. Adverse reactions were observed in 69 patients. Severe side effects were encountered in 13: four patients developed interstitial pneumonitis, four patients developed incessant ventricular tachycardia, three patients taking amiodarone and digoxin sustained sinus node arrest with depression of escape foci, one patient developed hepatitis, and one patient developed hypercalcaemia with renal failure. Furthermore, a rise in the serum concentration of digoxin and potentiation of warfarin anticoagulation occurred in cases in which these agents were combined with amiodarone. Amiodarone was stopped in 14 patients because of side effects. Although amiodarone is effective in suppressing arrhythmias in most patients in whom extensive use of antiarrhythmic drugs has been unsuccessful, it is associated with diverse and serious toxicity. These observations suggest that at present the use of amiodarone should be reserved for patients with life threatening or seriously disabling arrhythmias in whom longer established drugs have been ineffective or are contraindicated.

Differential anatomical location of [3H]-N,n-propylnorapomorphine and [3H]-spiperone binding sites in the striatum and substantia nigra of the rat

Specific [3H]-spiperone and [3H]-N,n-propylnorapomorphine (NPA) binding was measured in striatum and substantia nigra of the rat following unilateral 6-hydroxydopamine (6-OHDA) lesions of the medial forebrain bundle, kainic acid lesions of the substantia nigra or striatum, and following decortication. Binding sites labelled by [3H]-spiperone in striatum were found to lie on striatal cell bodies and on the terminals of cortico-striate glutamate fibres, but not on presynaptic dopamine terminals. In contrast, binding sites labelled by [3H]-NPA were demonstrated on striatal cell bodies and on the terminals of nigro-striata dopamine fibres, but not on cortical afferents. In substantia nigra, specific [3H]-spiperone binding sites were found only on non-dopamine cell bodies. No clear evidence was found for their existence on dopamine cell bodies, the terminals of strio-nigral fibres or the terminals of cortico-nigral fibres. In contrast, specific binding sites for [3H]-NPA were found on dopamine cell bodies and the terminals of strio-nigral fibres. Localization on non-dopamine cell bodies or on cortico-nigral fibres was not demonstrated. These studies support the concept of differential localization of agonist and antagonist binding sites.

Physiological predisposition toward becoming a cigarette smoker: experimental evidence for a sex difference

In two experiments, nonsmoking females whose urine was acidified were more willing after smoking one cigarette to volunteer to smoke additional cigarettes than were females whose urine was made alkaline. Males did not exhibit this effect. The results indicate that physiological factors that influence nicotine intake during the early smoking experiences of nonsmokers help determine who becomes a cigarette smoker, at least for females. These results may help us interpret recent increases in smoking among teenage females.

Relationship between plasma Ara-C and intracellular Ara-CTP pools under conditions of continuous infusion and high-dose Ara-C treatment

Plasma level Ara-C and Ara-U in vivo and intracellular Ara-CTP pools in vivo and in vitro were measured using high-performance liquid chromatography and radioimmunoassay. Plasma Ara-C during High Dose therapy was found in two phases; one, a peak at t1/2 of approximately 5-8 minutes, the other approaching that of Continuous Infusion with a t1/2 of about 6 to 8 hours. There appears to be no relationship between peak levels of plasma Ara-C and intracellular Ara-CTP formed during High Dose therapy. Intracellular Ara-CTP pools were found to be higher in peripheral blood than in bone marrow during High Dose treatment and were also higher in bone marrow of patients treated with High Dose rather than conventional dose Ara-C. In vitro experiments with various concentrations of Ara-C on patient cells prior to treatment suggest that patients may benefit from High Dose therapy when an increase in intracellular Ara-CTP occurred with higher extracellular concentrations of Ara-C. In patients with metabolically sensitive cells containing the necessary enzymes to activate Ara-C to Ara-CTP, where resistance is due to limited drug transport, High Dose therapy may prove beneficial. Conversely, in patients with no increase in Ara-CTP pools in vitro due to a depletion of activating enzymes, High Dose treatment may not be warranted. Therefore, it may be possible to determine patients most likely to benefit from High Dose chemotherapy by measuring pre-treatment in vitro intracellular Ara-CTP.

Centrally mediated hypotension and bradycardia by methysergide in anesthetized dogs

In anesthetized dogs, methysergide (1 and 3 mg/kg i.v.) caused reductions in systolic and diastolic blood pressure, heart rate, left ventricular pressure and peripheral resistance. Caardiac output was unchanged because of an increase in stroke volume. Methysergide exhibited no alpha-receptor, ganglion, or adrenergic neuron-blocking properties nor did it have marked direct vasocilator action. The BCO, but not the orthostatic, reflex was severely inhibited by the drug, evidence for a central inhibitory action. Atropine, vagotomy or carotid sinus debuffering had little or no effect on the hypotension and bradycardia produced by methysergide, whereas guanethidine pretreatment essentially abolished these effects. Direct intracerebronventricular administration of small doses of methysergide (0.2 mg/kg) caused significant hypotension and bradycardia. It is concluded that methysergide causes centrally mediated hypotension and bradycardia, the mechanism of which is not clearly understood.