Comparative analysis of parents' and teachers' view points on contraceptive practice among adolescents in Port Harcourt, Nigeria.

The study compares the viewpoint of parents and teachers on contraceptive practice by sexually active adolescents in the study environment The instrument for the study was a structured and pre-tested questionnaire. Data was analysed using frequency counts and chi-square statistical test of significance (P = .05). Findings showed that there was significant difference in opinion (P < 0.05) between parents and teachers on the use of contraceptives by adolescent girls. Most (79.1%) parents will not encourage girls to use contraceptives. However, a substantial number (45.8%) of teachers would similarly not encourage adolescents to use contraceptives. Various reasons are given by both repondents for discouraging adolescents from using contraceptives although there was significant difference (P < 0.05) in the reasons given. Based on the findings, it was concluded that for family planning programme directed towards adolescents to succeed parents' and teachers' view point must be put into consideration. In addition, teachers and parents need training in reproductive health.

L-2-chloropropionic acid inhibits glutamate and aspartate release from rat cerebellar slices but does not activate cerebellar NMDA receptors: implications for L-2-chloropropionic acid-induced neurotoxicity.

L-2-Chloropropionic acid (L-CPA), when orally administered at single high dose to rats produces a selective lesion in the cerebellum involving destruction of a high proportion of granule cells by a mechanism which involves N-methyl-D-aspartate (NMDA) receptors. Receptor binding studies demonstrated that L-CPA a had low affinity at the glutamate and glycine binding sites at NMDA receptors (530-660 microM), respectively, whereas L-CPA did not displace [3H]AMPA, [3H]NBQX or [3H]kainate from AMPA or kainate receptors. Whole cell-patch clamp experiments using cultured granule cells failed to demonstrate changes in membrane potential of cultured granule cells when either L-CPA (0.25 or 1 microM) was added alone to the bathing solution, or in combination with glycine (10 microM). Furthermore L-CPA did not alter the magnitude of the inward current produced by application of NMDA (100 microM)) to cultured granule cells, in the presence of glycine, as measured by patch clamp techniques. Experiments were also performed to discover whether L-CPA may alter the release of the excitatory amino acids from the cerebellum, which may then indirectly alter activity at glutamate receptors, leading to neuronal cell death. L-CPA (2 mM) did not affect either basal or stimulated (electrical or high potassium) endogenous aspartate release from superfused cerebellar slices nor did it alter the basal or stimulated release of [3H]aspartate from preloaded slices when introduced into the superfusion medium over 30 min. However, when cerebellar slices were preincubated with 2 mM L-CPA for 2 h at concentrations that are known to be neurotoxic to the brain in vivo, but not in vitro, the stimulated endogenous glutamate and aspartate net release was significantly attenuated, as compared to controls. Basal release was not significantly affected by the introduction of L-CPA-induced cerebellar neurotoxicity may be related to the inhibition of excitatory amino acid release from the cerebellum. In conclusion, although L-CPA does not appear to directly alter NMDA receptor activity the L-CPA-induced cerebellar neurotoxicity may be related to the inhibition of excitatory amino acid release from the cerebellum.

Effects of Zeneca ZD7288 in comparison with alinidine and UL-FS 49 on guinea pig sinoatrial node and ventricular action potentials.

ZENECA ZD7288 (4-(N-ethyl-N-phenyl-amino)-1,2-dimethyl-6-(methylamino) pyrimidium chloride) is a novel compound which we compared with alinidine and UL-FS 49 (zatebradine) in guinea pig sinoatrial node (SAN) and papillary muscle preparations, using conventional microelectrode techniques. At low concentrations (1 x 10(-8)-1 x 10(-6) M), ZD7288 caused slowing of the diastolic depolarisation rate of SAN pacemaker cells, thus prolonging the diastolic interval and slowing the beating rate. Alinidine and UL-FS 49 also had qualitatively similar effects on diastolic depolarisation rate, but ZD7288 caused least prolongation of the action potential duration (APD) of SAN cells at the concentrations that had "selective bradycardic actions." ZD7288 affected the APs of ventricular cells in guinea pig papillary muscle only at relatively high concentrations (3 x 10(-6)M-1 x 10(-4) M), which reduced plateau potential duration, although total APD was less affected. Reduced force of contraction (FOC) was also observed at these high concentrations; significant effects on AP Vmax were noted only at concentrations > or = 3 x 10(-5)M. Alinidine also had negative inotropic effects on papillary muscle, but its effects were noted at concentrations similar to those with bradycardic actions; in contrast, UL-FS 49 had marked positive inotropic actions and also increased ventricular APD within the bradycardic concentration range. These data provide a basis for the selective actions of ZD7288 on heart rate (HR).

Inhibitory actions of ZENECA ZD7288 on whole-cell hyperpolarization activated inward current (If) in guinea-pig dissociated sinoatrial node cells.

1. ZENECA ZD7288 (4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyridinium chloride) is a sinoatrial node (SAN) modulating agent which produces a selective slowing of the heart rate. Its effects have been studied in single, freshly dissociated guinea-pig SAN cells, by standard patch clamp procedures. 2. Whole-cell inward currents were evoked by hyperpolarizing voltage clamp steps from a holding potential of -40 mV. ZD7288 inhibited the hyperpolarization activated cationic current (If) in a concentration-dependent manner. The 'selective bradycardic agents' alinidine and UL-FS 49 (zatebradine) both also inhibited If. 3. The activation of If was investigated by measuring tail current amplitudes at +20 mV after hyperpolarizing steps to different potentials to activate the current. The reduction in If resulted from both a shift in the If current activation curve in the negative direction on the voltage axis, and also a reduction in the activation curve amplitude. 4. ZD7288 did not affect the ion selectivity of the If channel, since the tail current reversal potential was unchanged in the presence of the drug. 5. With ZD7288 the inhibition of If was not use-dependent, whereas UL-FS 49 displayed use-dependence in the block of the If current. 6. Whereas ZD7288 had no significant effect on the delayed rectifier current (Ik) in these cells, both alinidine and UL-FS 49 significantly reduced Ik at the same concentrations which reduced If. 7. The data show that ZD7288 reduces If by affecting the activation characteristics of the If current; this inhibition may account for this agent's selective bradycardiac properties.

Prevalence and causes of low vision and blindness in northern KwaZulu.

A survey of the prevalence of blindness and low vision was conducted in the Ingwavuma district of KwaZulu to assess the effectiveness of existing eye care facilities in the prevention and treatment of impaired vision and blindness. One hundred subjects from each of 60 randomly selected clusters (N = 6,090) were screened. Of these, 293 were identified and referred to an ophthalmologist for examination. Of the 268 (91,5%) examined, 241 were found to have visual impairment. Sixty-one of these people were blind, 85 had low vision, 61 were blind in one eye but had normal vision in the other, and 34 had low vision in one eye but normal vision in the other. The prevalence of blindness was 1,0% (95% confidence interval 0,7-1,2%), and the prevalence of impaired vision was 1,4% (95% confidence interval 1,1-1,7%). Age-related cataract (59,0%) and chronic glaucoma (22,9%) were the two main causes of blindness. Age-related cataract (75,3%), refractive error (10,0%) and chronic glaucoma (4,7%) were the main causes of impaired vision. Existing eye care services for the region have reduced the prevalence of blindness by only 7,0%. The training of ophthalmic nurses and the establishment of a sight-saver clinic in the area are necessary to reduce the prevalence of low vision and blindness.

ICI D7288, a novel sinoatrial node modulator.

We evaluated the cardiovascular effects of the sinoatrial (SA) node modulating agent, ICI D7288, in guinea pig isolated atria and SA node, anaesthetised and exercising dogs, and conscious rats. ICI D7288 (0.1-100 microM) caused a reduction in spontaneous beating rate in guinea pig isolated right atria without affecting the contractile force of paced left atria. The effect was associated with a reduction in the rate of diastolic depolarisation recorded intracellularly from pacemaker cells in the SA node. In anaesthetised dogs, ICI D7288 (0.02-1 mg/kg intravenously, i.v.) caused a dose-related reduction in heart rate (HR) without directly affecting left ventricular (LV) contractility. Exercise tachycardia in dogs was reduced by the compound (0.1-1 mg/kg i.v. and 0.3-10 mg/kg orally, p.o.). The increase in cardiac output (CO) during exercise was well maintained unless the tachycardia was reduced by > 30%, when it was attenuated. Administration of ICI D7288 p.o. (3-100 mg/kg) to conscious rats reduced HR by < or = 40%, but had no effects on blood pressure (BP). We suggest that ICI D7288, through its selective effects on the SA node, may be of use in treatment of ischaemic heart disease to reduce increased HR without impairing cardiac function.

Human bradykinin B2 receptor: nucleotide sequence analysis and assignment to chromosome 14.

Functional cDNA clones for human bradykinin B2 receptor were isolated from uterus RNA by a polymerase chain reaction (PCR)-based method and by screening a human cosmid library with rat bradykinin B2 receptor probe. We isolated several overlapping clones from the cosmid library, each of which encodes the entire protein coding sequence. The human bradykinin B2 receptor gene codes for a 364-amino-acid protein with a molecular mass of 41,442 Da that is highly homologous to rat bradykinin B2 receptor cDNA (81%). The entire human cDNA sequence was cloned into an expression vector and mRNA was synthesised by in vitro transcription. Applications of bradykinin caused membrane current responses in Xenopus oocytes injected with the in vitro-synthesized mRNA. Preincubation with the potent B2 antagonist, HOE140, prevented this response. The genomic clone is intronless, and we have identified an upstream promoter region and a downstream polyadenylation signal. The human bradykinin B2 receptor gene has been mapped to chromosome 14 using PCR to specifically amplify DNA from somatic cell hybrids.

Previous birth outcome of antenatal clinic attenders in northern KwaZulu--perinatal and infant mortality rates.

A questionnaire survey was undertaken among pregnant women presenting for the first time to antenatal clinics attached to Mosvold Hospital in rural northern KwaZulu. They were asked details of the outcome of their previous pregnancies and the survival of their last-born children. Of 2,388 mothers interviewed, 1,795 had given birth previously. Of these, 41% had had their last deliveries at home, 47% in hospital and 10% at clinics. The perinatal mortality rate was 38/1,000, with no significant differences between home and hospital or clinic births. The infant mortality rate for live-born children was 62/1,000. Fifty per cent of child deaths occurred at home. The study methodology was easily applied and provided an acceptable alternative technique for measuring child mortality rates, which are so difficult to obtain in rural areas in southern Africa.

Isolation and characterisation of the human lung NK-1 receptor cDNA.

Functional cDNA clones for human NK-1 receptor were isolated from human lung RNA using the polymerase chain reaction (PCR). We have screened a human cosmid library and isolated a clone which appeared to contain the entire NK-1 receptor gene. From the published rat NK-1 receptor cDNA sequence we designed primers within the protein coding sequence, but outwards towards both the 5' and 3' ends of the putative human protein sequence. By this method we derived DNA sequence from the 3' end of the human gene. In order to determine the 5' end of the gene we used a PCR based method called Rapid Amplification of cDNA Ends (RACE). From the derived human sequences amplimers were designed upstream of the ATG initiation codon and downstream of the stop codon. The entire cDNA was obtained by RNA-PCR from human lung RNA. The sequence obtained was 407 amino acids in length, encoding an open-reading frame that was highly homologous to the rat NK-1 receptor cDNA (89%). The entire human cDNA was then cloned into a mammalian expression vector and mRNA was synthesized by in vitro transcription. Applications of tachykinins caused membrane current responses in Xenopus oocytes injected with the in vitro synthesized mRNA. The most potent of the three tachykinin peptides tested was Substance P. The human NK-1 receptor gene has been mapped to chromosome 2 using the polymerase chain reaction to specifically amplify the human sequence in hamster/human hybrid DNA and also in mouse/human monochromosome hybrids.

Isolation and characterisation of the human lung NK-2 receptor gene using rapid amplification of cDNA ends.

Functional cDNA clones for human NK-2 receptor were isolated from human lung RNA using a polymerase chain reaction (PCR) based method (RACE-PCR). In this method the cDNA was isolated as 5' end and 3'-end fragments; the entire cDNA was obtained by RNA-PCR. The sequence derived was 398 amino acids in length encoding an open-reading frame that was highly homologous to both the bovine and rat NK-2 receptor. The entire human cDNA sequence was cloned into a mammalian expression vector and mRNA was synthesised by in vitro transcription. Applications of tachykinins caused membrane current responses in Xenopus oocytes injected with the in vitro synthesised mRNA. The most potent of the three tachykinin peptides tested was neurokinin A. We have screened a human cosmid library and isolated a clone which contains the entire NK-2 receptor gene. The gene contains five exons and we have determined the complete sequence of the exons and the intron-exon junctions.

Actions of opioids on the dorsal root potential of the isolated spinal cord preparation of the neonate rat.

The effects of opioids were studied on the dorsal root-dorsal root evoked potential (DRP) of the neonatal hemisected spinal cord of the rat in vitro. Applications of [D-Ala2,Met5]enkephalinamide (DAME), [D-Ala2,D-Leu5]enkephalin (DADL), Leu5 enkephalin, Met5 enkephalin, Dynorphin 1-9 and normorphine produced dose-dependent depressions of the dorsal root potential. The depressant effects of these agents were antagonised by naloxone but not by the highly selective delta-opioid receptor antagonist ICI 174864. Compounds acting on the kappa opioid receptor had only weak and inconsistent inhibitory effects on the dorsal root potential. Morphine had antagonist properties on the dorsal root potential, as did the kappa agonists ethylketocyclazocine and bremazocine, but not U50488 and tifluadom. The depressant actions of opioids on the dorsal root potential thus appeared to be mediated by actions on the mu receptor type. However, only mu agonists with relatively high intrinsic activity were able to reduce the dorsal root potential. Other mu agonists, including morphine, acted as antagonists. Actions on receptors for the delta and kappa agonists, in contrast, appeared to have little influence on this response. The antagonist actions of certain kappa agonists were probably due to their high affinity for, but low efficacy at mu receptors.

Analogues of substance P. Peptides containing D-amino acid residues in various positions of substance P and displaying agonist or receptor selective antagonist effects.

Agonist and antagonist analogues of substance P were synthesized by replacing at least two of the amino acid residues with D-Trp, D-Phe, D-Val, or D-Pro residues. The syntheses of these compounds were achieved by solid-phase methodology using the hydroxymethyl resin. The analogues were tested for agonist and antagonist activity on guinea pig ileum and rat spinal cord preparations. Two types of antagonists were obtained. The first type of compounds, e.g., [N alpha-Z-Arg1,N epsilon-Z-Lys3,D-Trp7,8,D-Met11]-SP-OMe (1), antagonized SP and SP(6-11)-hexapeptide on the ileum but only SP(6-11)-hexapeptide on the spinal cord. The second type of antagonists, e.g., [N alpha-Z-Arg1,N epsilon-Z-Lys3,D-Pro9,10]-SP-OMe (17), were inactive on the ileum but were potent antagonists of the hexapeptide on the spinal cord. Two of the antagonists, [N alpha-Z-Arg1,N epsilon-Z-Lys3,D-Trp7,8,D-Met11]-SP (3) and [D-Trp7,8,9]-SP (43), were also tested in vivo. Both of these depressed hypotensive responses to SP and SP(6-11)-hexapeptide in rabbits.

Antagonists of substance P. Further modifications of substance P antagonists obtained by replacing either positions 7, 9 or 7, 8 and 11 of SP with D-amino acid residues.

Antagonists of SP and the C-terminal (6-11)-hexapeptide have been obtained by multiple D-amino acid substitutions in various positions of SP and by protecting the N alpha-Arg1 and N epsilon Lys3 amino groups with benzyloxycarbonyl groups. On the guinea pig ileum a number of these antagonized both SP and the hexapeptide. Except [N alpha-Z-Arg1,D-Pro2,N epsilon-Z-Lys3,Asn5,Arg6,D-Phe7,D-Trp9]-SP-OMe (4) and the corresponding amide 7, which were more potent antagonists of SP than the hexapeptide, all the others, e.g., [N alpha-Z-Arg1,D-Pro2,4,N epsilon-Z-Lys3,D-Phe7,8,Sar9,D-Met11]-SP-OMe (9), [N alpha-Z-Arg1,D-Pro2,4,N epsilon-Z-Lys3,D-Phe7,8,Sar9,MeLeu10,D-Met11]-SP -OMe (11), were more potent antagonists of the hexapeptide. On the rat spinal cord preparation, most of the antagonists were only active against the hexapeptide. A few antagonized SP, but these also reduced carbachol or both carbachol and glutamate responses. Two of the antagonists, [D-Pro2,Asn5,Lys6,D-Phe7,D-Trp9]-SP-OMe (2) and [Boc-D-Pro4,D-Phe7,8,Sar9,D-Met11]-SP(4-11)-OMe (10), were inactive on the ileum but still antagonized the hexapeptide on the spinal cord. The smallest peptides to antagonize SP and the hexapeptide were two heptapeptides, 6 and 21, [Z-Asn5,Arg6,D-Phe7,8,Gly9 psi (CH2S)D-Leu10,D-Met11]-SP(5-11)-OMe (21) being more potent than 6. None of the antagonists showed significant analgesic activity without side effects. Some of the antagonists were shown to release histamine from isolated rat peritoneal cells.

Excitatoty effects of TRH on medullary reticular neurones.

Thyrotropin releasing hormone (TRH) was applied iontophoretically to single neruones in the rat bulbar reticular formation. TRH excited 41 to 56 cells tested; none were inhibited. Excitation developed slowly and was prolonged, and desensitization often occurred. TRH effects were not correlated with effects of acetylcholine, noradrenaline, dopamine or serotonin on the same cells. Atropine applied to cells affected by both acetylcholine and TRH did not affect TRH responses although the acetylcholine actions were blocked. The results support a transmitter role for TRH in this brain area and may explain certain arousal effects of TRH mediated via the reticular formation.

Spontaneous activity and responses of reticular neurones in monoamine-depleted rats.

Depletion of rat brain serotonin by p-chlorophenylalanine (PCPA) pretreatment, or of monoamines by reserpine pretreatment, was associated with reduced spontaneous firing rates of bulbar reticular neurones. Administration of 5-hydroxytryptophan to PCPA-treated rats reversed the reduction of neuronal activity. It is suggested that the results indicate a tonic excitatory serotoninergic input to a significant proportion of these neurones, which is abolished by serotonin depletion. Responses to serotonin and noradrenaline were greater in PCPA-treated and reserpire-treated rats respectively, indicating the development of supersensitivity.

Excitatory responses of neurones in rat bulbar reticular formation to bulbar raphe stimulation and to iontophoretically applied 5-hydroxytryptamine, and their blockade by LSD 25.

1. The micro-iontophoretic technique has been used to study the responses of single neurones in the bulbar reticular formation to 5-hydroxytryptamine and to noradrenaline, ACh or glutamate, and to compare these with the responses to electrical stimulation in or near the bulbar raphe nuclei. 2. In the bulbar reticular formation, most neurones were excited by 5-hydroxytryptamine; forty-three of fifty-one neurones excited by 5-hydroxytryptamine were also excited by stimulation in nucleus raphe magnus, nucleus raphe pallidus or nucleus raphe obscurus. Most of these stimulation-induced excitations were of long latency: LSD reduced six of seven of these excitations tested, while 5-hydroxytryptamine excitations were blocked on all seven. 3. In contrast, stimulation of areas adjacent to the raphe nuclei excited only fifteen of forty-six neurones excited by 5-hydroxytryptamine. Most of these stimulation effects were of short latency and none of the three tested were reduced by LSD, although 5-hydroxytryptamine excitations were blocked. 4. The relationship of the long-latency excitatory effects of stimulation with the position of the stimulating electrode in the raphe nuclei indicates that these effects are probably mediated via the raphe neurones and this is supported by the correlation of the effects of raphe stimulation with the effects of 5-hydroxytryptamine applied iontophoretically and by the ability of LSD to block both effects. 5. The results provide a physiological basis for the excitatory effects of iontophoretically applied 5-hydroxytryptamine in the bulbar reticular formation.