Pneumococcal disease among children in a rural area of west Africa

BACKGROUND

The pneumococcus is a frequent cause of pneumonia and other serious infections among young children in developing countries. Defining the pattern of pneumococcal infection in these countries is important so that, with the advent of pneumococcal conjugate vaccines, rational vaccination policies can be developed.

METHODS

Children younger than 5 years of age who attended clinics in a rural area of The Gambia, West Africa, were screened by assistants during a 2-year period. Children with predefined features suggestive of a diagnosis of pneumonia, meningitis or septicemia were referred to the Medical Research Council Field Station at Basse for investigation.

RESULTS

Of 2898 children investigated 103 cases of invasive pneumococcal disease (70 definite and 33 probable) were identified, suggesting that the incidence of this infection in the study community is at least 554/100,000/year in children younger than 1 year of age and 240/100,000/year in those younger than 5 years, rates many times higher than those found in industrialized societies. The mean age of presentation was 15 months; more boys than girls were affected. Cases of pneumonia were encountered 8 times more frequently than those of meningitis. Antibiotic resistance was rarely found and cases of pneumonia, but not meningitis, responded well to treatment. Case-fatality rates in children with pneumonia and meningitis were 1 and 55%, respectively. The most prevalent pneumococcal serotypes were types 6, 14, 19, 1 and 5.

CONCLUSION

About 60% of invasive pneumococcal infection in children in this community could potentially be prevented by a nine-valent pneumococcal conjugate vaccine (types 1, 4, 5, 6B, 9, 14, 18, 19F and 23) given at the ages of 2, 3 and 4 months.

Irritable bowel syndrome: a study to investigate the mechanism(s) of visceral hypersensitivity

Irritable bowel syndrome (IBS), is characterized by gastrointestinal hyperalgesia. In this study we investigated mucosal application of dyclonine on urge to defecate and pain threshold in volunteers and IBS patients (n = 10). Either saline or dyclonine (40 ml enema) was administered 10 minutes prior to rectosigmoid distension or cutaneous cold water pressor test. In IBS patients and volunteers no differences in cutaneous pain thresholds were noted. However, IBS patients had a lower pain threshold in the rectosigmoid than volunteers. In volunteers there was a significant difference between the threshold for urge to defecate and the threshold for rectosigmoid pain that was not apparent in IBS patients. Dyclonine administered directly into the rectosigmoid did not alter urge to defecate or pain threshold induced by distension in volunteers or IBS patients. These data suggest that the origin of pain perception is localized in deeper structures within the wall of the rectosigmoid colon.

A randomized trial of chloroquine, amodiaquine and pyrimethamine-sulphadoxine in Gambian children with uncomplicated malaria

The increasing occurrence of chloroquine-resistant Plasmodium falciparum in sub-Saharan Africa makes it essential to reconsider current recommendations for the treatment of uncomplicated P.falciparum malaria. In an open, randomized trial, we have compared chloroquine (CQ), amodiaquine (AQ), and pyrimethamine-sulphadoxine (PS) in rural Gambian children with uncomplicated P.falciparum malaria. Three hundred children were randomly assigned at the time of consultation (Do) to oral treatment with 25 mg/kg CQ, 25 mg/kg AQ (both given over 3 days), or 1.25/25 mg/kg PS. They were reviewed on day 7 (D7) and day 28 (D28) for symptoms, malaria parasitaemia, and packed cell volume (PCV). Significantly more children treated with PS compared to CQ (17 vs 7%, P = 0.03) or AQ (17 vs 3%, P = 0.001) returned with clinical complaints during the first 3 days after treatment. Five of these patients had a generalized convulsion (1 from the AQ group, 4 from the PS group), of whom 4 developed cerebral malaria. At D7, significantly more patients treated with CQ compared to AQ (25 vs 7%, P = 0.0009) or PS (25 vs 4%, P = 0.0001) were parasitaemic. By D28, the cumulative number of parasitological failures was significantly higher in the CQ group compared to the AQ group (65 vs 35%, P = 0.0001), and significantly higher in the AQ group compared to the PS group (35 vs 14%, P = 0.001). Overall, 91% of parasitological failures observed during the study period were symptomatic and were consequently treated with an alternative antimalarial drug. Over the 28-day study period the mean PCV increased significantly less in the CQ group than in the PS group (1.2 vs 3.8%, P = 0.016) and was lower in the CQ group than in the AQ group (1.2 vs 2.7%, P = 0.12, not significant). These results suggest that PS acts more slowly than 4-aminoquinolines in controlling the clinical features of malaria, and that AQ can be considered as an interim alternative to CQ in the first-line therapy of uncomplicated malaria in African areas of high CQ resistance.

Activation of the hypothalamic dorsomedial nucleus stimulates intestinal motility in rats

Blockade of gamma-aminobutyric acidA (GABAA) receptors in the dorsomedial nucleus of the hypothalamus (DMH) in rats induced cardiovascular and behavioral changes resembling those associated with emotional stress. The purpose of this study was to test the hypothesis that microinjection of the GABA antagonist bicuculline methiodide (BMI) into the DMH of anesthetized rats would produce increases in intestinal motility measured manometrically with saline-filled cannulas. Arterial pressure and heart rate were also recorded. Microinjection of BMI (15-30 pmol/15 nl) into the region of the DMH elicited reproducible and dose-related increases in jejunal motility, colonic motility, heart rate, and arterial pressure. Similar microinjection at sites anterior to the DMH into or nearer to the hypothalamic paraventricular nucleus elicited significantly attenuated cardiovascular effects accompanied by either no change in intestinal function or changes that were significantly reduced. Either vagotomy or treatment with atropine methyl bromide (1 mg/kg i.v.) blocked the increase in jejunal motility and reduced but did not abolish the colonic stimulation. Increases in heart rate and arterial pressure were essentially unaffected by either intervention. The observations suggest that disinhibition of neurons in the DMH increases jejunal motility through vagal cholinergic pathways and enhances colonic motility through vagal and nonvagal cholinergic and noncholinergic pathways.

Financing mechanisms for village activities in The Gambia and their implications for financing insecticide for bednet impregnation

The recent enthusiasm for impregnated bednets as a malaria control measure leaves unresolved the question of how to finance them. The National Impregnated Bednet Programme in The Gambia faced the question of how to obtain funds from villages to finance the cost of insecticide, but knew very little about current village fundraising for development purposes. A survey was conducted of such fundraising, and questions also asked about willingness to pay for insecticide and preferred means of paying. All 53 villages surveyed paid taxes/rates, but 34% of villages reported no voluntary fundraising. The most common reason for collecting money was for the maintenance of wells (40% of villages). Collective farming was used as a means of raising money in 32% of villages. There was some variation in the type and extent of fundraising by region and also by the predominant ethnic groups of the village. Villages with voluntary fundraising activities seemed to have well established collective mechanisms for agreeing on sums to be collected and their use, and for collecting and recording income and expenditure. Non-payment was rare, and misuse of funds was not reported. Respondents were asked how much compounds might be willing to pay for insecticide impregnantion: the most frequently cited maximum amounts were D5 and 10, and minimum D1 and 5 (D15 = 1 pound). The paper discusses payment options for insecticide, such as whether the village should be allowed to decide itself how to raise funds, and whether the payment should be made only by households with nets or by a village-wide mechanism such as collective farming.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast cancer: causes of patients' distress identified by qualitative analysis

BACKGROUND

Previous investigations of the psychological consequences of having breast cancer have usually involved quantitative analysis within medical models.

AIM

This qualitative study set out to identify key events which had caused distress to women with breast cancer and to compare the frequency of these events with doctors' beliefs about their relative frequency.

METHOD

The causes of distress in 26 women with breast cancer were identified by qualitative analysis of unstructured interviews. Subsequently, all hospital doctors and general practitioners in the Exeter health district were sent a list in random order of the eight events which had most commonly caused distress and were asked to rank them in order of frequency for patients with breast cancer.

RESULTS

The responses suggest a mismatch between the doctors' expectations and the experience of the patients.

CONCLUSION

Patients may suffer distress in areas of management doctors do not suspect are important; qualitative analysis can identify these areas.

Detection of Streptococcus pneumoniae DNA in blood cultures by PCR

We have developed a PCR assay, with primers derived from the autolysin (lyt) gene, for the detection of Streptococcus pneumoniae DNA in blood cultures. The predicted fragment of 247 bp was detected in all strains of pneumococci, embracing 12 different serotypes that were tested. Although DNA extracted from four viridans streptococci spp. Streptococcus oralis, Streptococcus mitis, Streptococcus sanguis, and Streptococcus parasanguis) gave amplification products, these were quite different from the predicted fragment for S. pneumoniae. Application of the assay for diagnosis of septicemia caused by S. pneumoniae showed concordance between PCR and culture results. However, on four occasions PCR was positive in supernatants from both paired culture bottles while pneumococci were cultured from only one. Performing PCR on negative cultures in controlled studies such as vaccine trials may provide a sensitive tool for increasing case detection.

Xanomeline: a novel muscarinic receptor agonist with functional selectivity for M1 receptors

Xanomeline [3(3-hexyloxy-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1- methylpyridine] has been evaluated as a muscarinic receptor agonist. In vitro, xanomeline had high affinity for muscarinic receptors in brain homogenates, but had substantially less or no affinity for a number of other neurotransmitter receptors and uptake sites. In cells stably expressing genetic m1 receptors, xanomeline increased phospholipid hydrolysis in CHO, BHK and A9 L cells to 100, 72 and 55% of the nonselective agonist carbachol. In isolated tissues, xanomeline had high affinity for M1 receptors in the rabbit vas deferens (IC50 = 0.006 nM), low affinity for M2 receptors in guinea pig atria (EC50 = 3 microM), was a weak partial agonist in guinea pig ileum and was neither an agonist nor antagonist in guinea pig bladder. In vivo, xanomeline increased striatal levels of dopamine metabolites, presumably by acting at M1 heteroreceptors on dopamine neurons to increase dopamine release. In contrast, xanomeline had only a relatively small effect on acetylcholine levels in brain, indicating that it is devoid of actions at muscarinic autoreceptors. In the gastrointestinal tract, xanomeline inhibited small intestinal and colonic motility, but increased small intestinal transmural potential difference. In contrast to the nonselective muscarinic agonist oxotremorine, xanomeline did not produce salivation, tremor nor hypothermia; it did, however, increase heart rate. The present data are consistent with the interpretation that xanomeline is a novel muscarinic receptor agonist with functional selectivity for M1 muscarinic receptors both in vitro and in vivo.

Effects of LY267108, an erythromycin analogue derivative, on lower esophageal sphincter function in the cat

BACKGROUND/AIMS

Erythromycin (EM-A) and some of its analogues stimulate gastrointestinal smooth muscle contractions. Because gastroesophageal reflux disease (GERD) in humans is in part caused by a reduction in lower esophageal sphincter (LES) pressure, the aim of this study was to investigate the effect of LY267108 (an EM-A analogue with no significant antimicrobial activity) on LES function.

METHODS

In ketamine-anesthetized cats, LES pressure was recorded using a Dent sleeve.

RESULTS

In cats, LY267108 increased LES pressure, as did motilin and EM-A. Neither LY267108, EM-A, nor motilin altered LES relaxation in response to a swallow. LY267108 increased LES pressure in cats in which the basal LES pressure was lowered experimentally by perfusing the distal esophagus with HCl (0.1 N for 3 days) or following isoproterenol (3.0 micrograms/kg intravenously). In summary, LY267108 increases LES pressure in normal cats, did not affect the relaxation of the LES in response to a swallow, and increases LES pressure in animals with an experimentally induced decrease in LES pressure.

CONCLUSIONS

The results suggest that LY267108 may be useful in treating GERD because of its ability to increase LES pressure and thus present a barrier for gastroesophageal reflux.

Regional content of enteric substance P and vasoactive intestinal peptide during intestinal inflammation in the parasitized ferret

Our aim was to characterize and quantitate changes in two key neuropeptides, substance P (SP) and vasoactive intestinal peptide (VIP), that are involved in governing neurally-mediated gastrointestinal (GI) reflex activity during enteric inflammation in the ferret. Neuropeptide content was determined by radioimmunoassay of extracts of jejunal, ileal and colonic muscularis externa from uninfected ferrets and ferrets infected with enteric stages of the parasitic nematode, Trichinella spiralis. Increased myeloperoxidase activity (MPO), an enzymatic marker of inflammation, occurred in all three gut regions. Histopathological changes were present only in the small intestine. Significant reductions were detected in both SP (72% decrease) and VIP (62% decrease) in the inflamed jejunum. Ileal concentrations of both SP (77% decrease) and VIP (46% decrease) were also decreased during T. spiralis infection compared to uninfected ferrets. Only SP (58% decrease) concentration showed a significant change in colonic tissues from infected ferrets; colonic VIP was unaltered. Parasite-induced inflammation caused significant changes in peptide-containing enteric neural pathways and might contribute to functional GI motor disturbances that occur during nematode infections in mammalian hosts.

Controlled trial of lambda-cyhalothrin impregnated bed nets and Maloprim chemosuppression to control malaria in children living in a holoendemic area of Sierra Leone, west Africa. Study design and preliminary results

The effect of lambda-cyhalothrin impregnated bed nets and maloprim/placebo was studied in approximately 1,500 children living in 17 villages in a rural area of Sierra Leone, approximately 150 miles south east of Freetown, 30 miles north of the town of Bo. Villages were selected randomly amongst villages with impregnated bed nets and villages with no nets at all. Within these villages, children with ages ranging between 3 months to 6 years were chosen to receive maloprim or a double-blind distributed placebo fortnightly. In the villages randomised to receive nets, all beds have received nets. Malaria morbidity is estimated from weekly active case detection, and the impact on the Anopheles vector is being estimated by indoor spray catching, exit trap catching, human night landing catches and light trap catches. During the first 8 weeks of the intervention there was a significant reduction in slide positive rates, reported fever rates and children with temperature > or = 37.5 degrees C in the villages with impregnated bed nets.

An improved microassay for Plasmodium falciparum cytoadherence using stable transformants of Chinese hamster ovary cells expressing CD36 or intercellular adhesion molecule-1

Stable transformants of Chinese hamster ovary (CHO) cell lines expressing high levels of human CD36 or intercellular adhesion molecule-1 (ICAM-1) have been produced as target cells for cytoadherence of Plasmodium falciparum-infected erythrocytes. An improved adherence microassay has been designed using small sample volumes and allowing convenient and reliable measurements on a large number of samples. The assay can be used both with purified proteins spotted on plastic and with the stably transformed CHO cell lines. The same assay plate can be evaluated either microscopically or by scintillation counting after use of 3H-hypoxanthine-labeled parasites. Using the microassay, functional expression of the transfected receptor molecules on CHO-CD36 and CHO-ICAM was confirmed using parasites with different cytoadherence phenotypes and cytoadherence inhibition experiments with a panel of anti-CD36 antibodies. The use of isolates from The Gambia confirmed the applicability of these assays for laboratory studies of these isolates.

Spontaneous neoplasia in the ferret (Mustela putorius furo)

Thirteen spontaneous tumours in ferrets from two laboratory breeding colonies are described, including two types not previously reported in this species, namely, uterine teratoma and neurilemmoma. The literature on tumours in laboratory and domestic ferrets is comprehensively reviewed from the first reported case in 1950. Only 20 cases were reported from 1950 to 1979, nearly all from laboratory or zoological collections. In the following 10 years more than 170 further cases were reported, about half of them in domestic pet ferrets. A review of the limited literature on tumours in related species reveals substantial incidences in black-footed ferrets and ranch mink allowed to live out their lifespan, and isolated cases in polecats and at least eight other species of Mustelidae.

The cost-effectiveness of chemoprophylaxis with Maloprim administered by primary health care workers in preventing death from malaria amongst rural Gambian children aged less than five years old

In recent trials in The Gambia, mass chemoprophylaxis with Maloprim administered over several years by primary health care workers to children aged 3-59 months has reduced both mortality and morbidity without inducing impairment of natural immunity or significant development of drug resistance. Taking expenditure of both time and money, by both public authorities and village volunteers, into account, the costs and the cost effectiveness of such mass chemoprophylaxis are estimated here. The cost per child protected per season was (1990 US) $2.84; the cost per childhood death averted was $143. Both costs compare favourably with those of permethrin bed net impregnation. So in some circumstances where malaria is holoendemic, control of childhood malaria by chemoprophylaxis may be more economically efficient than provision of impregnated bed nets.

Mucin and protein release in the rabbit jejunum: effects of bethanechol and vagal nerve stimulation

The role of the vagus nerve and cholinergic mechanisms in the control of rabbit jejunal mucin and protein release was investigated in vivo. In anesthetized animals, a 10-cm segment of the jejunum was cannulated and perfused with saline. Perfusate was collected and analyzed for mucin (by immunoassay) and protein. Bilateral cervical vagotomy had no effect on basal mucin or protein output, suggesting that the vagus nerve does not exert a tonic control on jejunal macromolecule secretion. Electrical stimulation of the vagi did not alter mucin release, even in the presence of muscarinic cholinergic (scopolamine) or adrenergic (propranolol and phentolamine) blockade. In contrast, protein output increased significantly after vagal stimulation, an effect inhibited by scopolamine. In both vagotomized and vagally intact rabbits, the cholinergic agonist bethanechol (200 micrograms/kg intraperitoneally) induced a scopolamine-sensitive increase in both mucin and protein output. Predominantly serum proteins were released into intestinal perfusates after vagal or cholinergic stimulation. It is concluded that the extrinsic vagus nerve does not regulate rabbit jejunal mucin secretion in vivo and that cholinergic control of intestinal goblet cells is implemented entirely by the intrinsic enteric nervous system. In addition, cholinergic or vagal stimulation increases intestinal vascular and epithelial permeability, resulting in the passage of serum proteins into the lumen, possibly by opening tight junctions and paracellular pathways.

Epidemiology of acute lower respiratory tract infections, especially those due to Haemophilus influenzae type b, in The Gambia, west Africa

Mortality surveys undertaken in rural areas of The Gambia, a small country on the west coast of Africa, indicate that acute lower respiratory tract infections (ALRI) are the most frequent cause of death among children and that approximately 1 in 25 rural Gambian children dies from an ALRI before the age of 5 years. Community surveys suggest that each child experiences an average of one episode of ALRI accompanied by radiographic changes before reaching this age. Etiologic studies have shown that pneumococci, Haemophilus influenzae type b (Hib), and respiratory syncytial virus are the most important causes of ALRI in Gambian children who present to a hospital, and the same three organisms are probably the major causes of severe ALRI in rural communities. Hib probably accounts for 5%-10% of cases of severe ALRI in Gambian children, and because the incidence of severe ALRI is high, an effective Hib conjugate vaccine might save as many childhood deaths by preventing pneumonia as by preventing meningitis.

Prostaglandins and modulation of small bowel myoelectric activity

We explored the effects of prostaglandins (PG) F2 alpha and E2 on the motor and myoelectric activity of the small intestine using closed intra-arterial injections in conscious chronically instrumented dogs. PGF2 alpha (0.125-5 micrograms) and PGE2 (1-10 micrograms) were injected via a T tube into a branch of the superior mesenteric artery perfusing a 15-cm segment of jejunum. Experiments were performed on four dogs in which the recording devices had been implanted above, below, and within the perfused segment. PGF2 alpha given during phase I of the migrating myoelectric complex cycle induced phasic contractions in the perfused segment of intestine in a dose-dependent manner. Atropine (50-100 micrograms), hexamethonium (15 mg), or TTX (10-15 micrograms) administered before the injection of PGF2 alpha failed to inhibit the effects of PGF2 alpha. In contrast pretreatment of the perfused segment with verapamil (2.5 mg) or PGE2 (1-5 micrograms) abolished the effects of PGF2 alpha. Moreover, PGE2 injected 5 min after the administration of PGF2 alpha inhibited the PGF2 alpha-induced contractions. Administration of PGE2 alone (3-10 micrograms) before the arrival of phase III activity in the perfused segment abolished phase III from this segment of intestine. Our studies indicate opposing effects of PGF2 alpha and PGE2 on small intestinal myoelectric and contractile activities. PGF2 alpha has a direct excitatory effect on the intestinal smooth muscle, which is calcium channel dependent but independent of intrinsic nerves. PGE2 has an inhibitory effect both on the spontaneous and PGF2 alpha-induced small intestinal myoelectric and contractile activity.

Nicotine stimulates esophageal peristaltic contractions in cats by a central mechanism

The aim of the present study was to 1) characterize nicotine-induced peristalsis in the feline esophagus and 2) determine the site of action of nicotine. Experiments were done on ketamine-sedated cats. Esophageal contractions were measured using a multilumen catheter assembly system. After recording 1 degree and 2 degrees peristaltic sequences nicotine (50-100 micrograms/kg iv) was administered. Nicotine induced a peristaltic contraction through the esophageal striated and smooth muscle part of the esophagus, which was not associated with any mylohyoid electromyogram activity or pharyngeal response, although the upper esophageal sphincter did relax. Addition of either atropine (20-50 micrograms/kg iv) or hexamethonium (10-20 mg/kg iv), a peripherally acting nicotinic antagonist, did not affect the striated muscle portion of the nicotine-induced esophageal contractile response but antagonized the smooth muscle response. However, mecamylamine (0.5-1 mg/kg iv), a ganglionic antagonist that crosses the blood-brain barrier, abolished the esophageal response to nicotine. Succinylcholine (0.5-1 mg/kg iv) abolished the striated muscle response without affecting the nicotine-induced smooth muscle contractility. Finally, the nicotine-induced peristaltic sequence was abolished after bilateral cervical vagotomy. In conclusion, nicotine, administered peripherally, activates central brain stem mechanisms that mediate a peristaltic sequence through the feline esophagus.

Effect of mebeverine hydrochloride on jejunal motility and epithelial transport in the anesthetized ferret

Previous in vitro and in vivo studies demonstrate that mebeverine, administered to isolated smooth muscle preparations or given intravenously, (i.v.), acts as an antispasmodic agent and may be useful in treating intestinal hypermotility. Whether mebeverine affects intestinal mucosal transport is, however, unknown. The aim of the present study was to characterize the effect of mebeverine on both small intestinal motor activity and electrogenic epithelial transport in the urethane anesthetized ferret. The effects of mebeverine were compared following i.v. and intrajejunal (i.j.) administration. Following both routes of drug administration mebeverine dose dependently inhibited jejunal motility, with the i.j. route being more potent. However, when administered i.v. but not i.j., the doses of mebeverine that inhibited jejunal motility also significantly reduced heart rate and arterial blood pressure. Mebeverine (0.1-10 mg/kg) administered i.v. had no significant effect on epithelial transport as measured by a change in transmural potential difference. However, when dosed i.j., mebeverine (0.1-10 mg/kg) induced a decrease in potential difference towards lower lumen negativity, which was suggestive of a decrease in fluid secretion or enhancement of absorption. In conclusion, the results confirm in vivo the antispasmodic effect of mebeverine and suggested that mebeverine can influence epithelial transport, probably in the direction of enhanced intestinal absorption.

DNA fingerprinting in the epidemiology of African serogroup A Neisseria meningitidis

The restriction endonuclease (RE) technique was used to compare 172 meningococcal group A strains collected between 1969 and 1990, mainly from countries of the so-called African Meningitis Belt, the Gambia and Ethiopia. The 64 strains from various African countries (Niger, Chad, Burkina Faso, Cameroon, Morocco, Djibouti) were distributed within 3 main restriction enzyme patterns (REPs); the 77 Gambian strains fell into 5 REPs and the 24 Ethiopian strains into 2 such patterns. Several of the main REPs were formed by clusters of closely related clones. Clones, very similar to dominating REPs of the 1960s in Niger, Burkina Faso and Cameroon, were in the 1980s found to be strongly represented in the Gambia to the extreme west of the Meningitis Belt. One of the Gambian clones from 1983-86 was identical to an Indian clone recovered in New Delhi 1986-87. Another clone was detected in 1983 in the Gambia, in 1989 again in the Gambia as well as in Ethiopia, and in 1990 in Tanzania. Our results are largely in line with those of previous studies based on modern techniques of protein and isoenzyme electrophoresis. The RE method is useful mainly for the exact genotypic differentiation of closely related clones, and seems to be a valuable complement to phenotypic tools for epidemiological mapping of Group A meningococcal infection.