Identification of the vectors of lymphatic filariasis in the Lower Shire Valley, southern Malawi

An investigation of lymphatic filariasis vectors in Malawi is reported. Anopheles funestus, A. arabiensis, and A. gambiae sensu stricto had high rates of filarial infection (2.2-3.1%) and carried infective larvae. Anopheles funestus was the predominant species collected (77.6%) and was the primary vector during the study period of April to May 2002.

Genetic structure of Anopheles gambiae (Diptera: Culicidae) in São Tomé and Príncipe (West Africa): implications for malaria control

The impact of a vector eradication programme, conducted in the 1980s, on Anopheles gambiae populations from the islands of São Tomé and Príncipe, was evaluated by microsatellite DNA analysis. Significant genetic differentiation was observed within and between the two islands and between the islands and a population from Gabon, suggesting a degree of isolation between them. Large estimates of long-term N(e) suggested that the control programme did not affect the effective population size of the vector. Heterozygosity tests were also not consistent with a recent bottleneck.

Evidence for recent population expansion in the evolutionary history of the malaria vectors Anopheles arabiensis and Anopheles gambiae

Gene flow in malaria vectors is usually estimated based on differentiation indices (e.g., F(ST)) in order to predict the contemporary spread of genes such as those conferring resistance to insecticides. This approach is reliant on a number of assumptions, the most crucial, and the one most likely to be violated in these species, being mutation-migration-drift equilibrium. Tests of this assumption for the African malaria vectors Anopheles gambiae and Anopheles arabiensis are the focus of this study. We analyzed variation at 18 microsatellite loci and the ND5 region of the mitochondrial genome in two populations of each species. Equilibrium was rejected by six of eight tests for the A. gambiae population from western Kenya and by three tests in eastern Kenya. In western Kenya, all departures from equilibrium were consistent with a recent population expansion, but in eastern Kenya, there were traces of a recent expansion and a bottleneck. Equilibrium was also rejected by two of the eight tests for both A. arabiensis populations; the departure from equilibrium was consistent with an expansion. These multiple-locus tests detected a genomewide effect and therefore a demographic event rather than a locus-specific effect, as would be caused by selection. Disequilibrium due to a recent expansion in these species implies that rates of gene flow, as inferred from differentiation indices, are overestimates as they include a historical component. We argue that the same effect applies to the majority of pest species due to the correlation of their demography with that of humans.

Evidence for extensive genetic differentiation among populations of the malaria vector Anopheles arabiensis in Eastern Africa

We describe the geographical population structure of the malaria vector Anopheles arabiensis in Eastern Africa. Allelic variation at eight microsatellite loci was scored in samples from nine localities along a 4500 km transect from Sudan to Mozambique. Highly significant differences in genotype frequencies were found between all populations separated by more than 200 km. Populations within Malawi separated by 191 km were indistinguishable, as were those within Sudan separated by 134 km. FST and rhoST gave significant estimates of isolation by distance. These data, lead us to conclude that there are extensive barriers to gene flow in this region. The high estimates of Nm (9.4 from FST and 5.2 from rhoST) indicate recent range expansion in this species rather than extensive contemporary gene flow.

Macrofilaricidal activity of tetracycline against the filarial nematode Onchocerca ochengi: elimination of Wolbachia precedes worm death and suggests a dependent relationship

Filarial nematodes are important and widespread parasites of animals and humans. We have been using the African bovine parasite Onchocerca ochengi as a chemotherapeutic model for O. volvulus, the causal organism of 'river blindness' in humans, for which there is no safe and effective drug lethal to adult worms. Here we report that the antibiotic, oxytetracycline is macrofilaricidal against O. ochengi. In a controlled trial in Cameroon, all adult worms (as well as microfilariae) were killed, and O. ochengi intradermal nodules resolved, by nine months' post-treatment in cattle treated intermittently for six months. Adult worms removed from concurrent controls remained fully viable and reproductively active. By serial electron-microscopic examination, the macrofilaricidal effects were related to the elimination of intracellular micro-organisms, initially abundant. Analysis of a fragment of the 16S rRNA gene from the O. ochengi micro-organisms confirmed them to be Wolbachia organisms of the order Rickettsiales, and showed that the sequence differed in only one nucleotide in 858 from the homologous sequence of the Wolbachia organisms of O. volvulus. These data are, to our knowledge, the first to show that antibiotic therapy can be lethal to adult filariae. They suggest that tetracycline therapy is likely to be macrofilaricidal against O. volvulus infections in humans and, since similar Wolbachia organisms occur in a number of other filarial nematodes, against those infections too. In that the elimination of Wolbachia preceded the resolution of the filarial infections, they suggest that in O. ochengi at least, the Wolbachia organisms play an essential role in the biology and metabolism of the filarial worm.

Head and neck schwannomas--a 10 year review

Schwannomas of the head and neck are uncommon tumours that arise from any peripheral, cranial or autonomic nerve. Twenty-five to 45 per cent of extracranial schwannomas occur in the head and neck region and thus are usually in the domain of the otolaryngologist. They usually present insidiously and thus are often diagnosed incorrectly or after lengthy delays, however, better imaging and cytological techniques have lessened this to some degree more recently. For benign lesions conservative surgical excision is the treatment of choice bearing in mind possible vagal or sympathetic chain injury. Malignant schwannomas are best treated with wide excision where possible. The role of adjuvant therapy remains uncertain and irrespective of treatment modality prognosis is poor with an overall survival of 15 per cent. However, recent advances in ras oncogene inhibitors may hold hope for the future.

Population structure in the malaria vector, Anopheles arabiensis patton, in East Africa

The population structure of the malaria vector Anopheles arabiensis was investigated using data from six microsatellite loci in samples from localities in Mozambique and Tanzania. Genotype frequencies were neither significantly different between houses in a village in Tanzania nor between villages within a 20-km radius in Mozambique. Thus a deme has an area greater than 20 km in radius. At five of the six loci the heterozygosity of the population from Mozambique was lower than that from Tanzania, implying a lower effective population size (Ne) at this southern edge of the species range. There were significant differences in genotype frequencies between the Tanzanian and Mozambique populations at five of the six loci (P<0.05). Values for both FST (mean=0.069) and RST (mean=0.025) were significantly different from zero (P<0.05) at four and three out of five loci, respectively, but there was no significant correlation between the two statistics. The wide variation in values of FST and RST across loci suggests that care should be taken in interpreting values derived from averaging across loci. Whether the variation results from sampling effects or selectional constraints on some loci is unclear. Although there is evidence for significant differentiation between these populations, estimates of gene flow (Nm) calculated from mean FST and RST statistics were relatively high, 3.4 and 4.9, respectively. We argue that this is more likely to reflect recent separation of these populations and/or large effective population size rather than large-scale present day migrations.

Second malignancies in patients treated for childhood acute lymphoblastic leukemia

PURPOSE

Second malignant neoplasms (SMN) are devastating late complications of childhood acute lymphoblastic leukemia (ALL) and its treatment. We evaluated the incidence and type of SMN diagnosed before leukemic relapse in a large series of patients with ALL.

PATIENTS AND METHODS

We reviewed the outcome of all patients treated for childhood ALL between 1972 and 1995 on Dana-Farber Cancer Institute (DFCI) and DFCI ALL Consortium protocols. The follow-up time from diagnosis of ALL to induction failure, relapse, remission death, or SMN, whichever occurred first, ranged from 0 to 24.0 years (median, 7.6 years; mean, 6.7 years).

RESULTS

Thirteen SMNs were diagnosed among 1,597 patients. Eight tumors occurred in a radiation field (five in the CNS and three in the head and neck), two occurred outside of a radiation field (one adenocarcinoma of the sigmoid colon and one epithelioid sarcoma of the chest wall), and three were hematopoietic malignancies. The median time to occurrence was 6.7 years (range, 1.0 to 17.2 years) and the cumulative incidence of second malignancy before another first event was 2.7% (95% confidence interval, 0.7 to 4.7). The risk of a first event, which included induction failure, relapse, or remission death, was 31.0% (95% confidence interval, 28.5 to 33.5).

CONCLUSION

We found a more than 10-fold risk of other first events when compared with SMN. Thus, we conclude that SMN before first relapse is a relatively uncommon occurrence among survivors of childhood ALL. Future therapeutic regimens must focus on reducing leukemia relapse and enhancing quality of life, as well as preventing SMNs.

Intensified therapy for infants with acute lymphoblastic leukemia: results from the Dana-Farber Cancer Institute Consortium

BACKGROUND

Infants with acute lymphoblastic leukemia (ALL) have a very poor prognosis. Since 1985, we have intensified therapy for infants with ALL by including a month of high dose multiagent chemotherapy after remission induction.

METHODS

Between 1985 and 1995, we treated 23 infants (age < 12 months). We compared the presenting characteristics and outcomes of these infants with the 11 infants treated on our protocols between 1973 and 1985, an era prior to the intensification of therapy. Available bone marrow samples from infants treated since 1985 were analyzed for the presence of MLL gene rearrangements by Southern blot analyses and for TEL-AML1 gene fusion by reverse transcriptase-polymerase chain reaction.

RESULTS

With a median follow-up of 5.6 years, the 50-month event free survival (EFS) (+/- standard error) for the 23 infants was 54 +/- 11%, a significant improvement (P = 0.001) compared with the outcome for the 11 infants treated on our protocols prior to 1985 (EFS = 9 +/- 9%). Of the seven infants found to have a rearranged MLL gene, three (43%) remained in first complete remission. None of the nine infant bone marrow specimens tested had evidence of TEL-AML1 gene fusion. The intensified therapy was complicated by a high incidence of infections, including septicemia in 52% of patients and Pneumocystis carinii pneumonitis in 22% of patients. Late effects identified in the 13 long term survivors (median age, 6 years) included developmental delay and learning disabilities of varying severity (82% of evaluable patients), asymptomatic cataracts (67%), asymptomatic echocardiographic abnormalities (30%), obesity (27%), and short stature (18%).

CONCLUSIONS

Intensification of therapy significantly improved the EFS of infants with ALL compared with previous, less intensive regimens and with the experience of other investigators. Future treatment for infants should attempt to improve efficacy while minimizing toxicity.

Acute food bolus impaction: aetiology and management

A prospective study into the aetiology of acute food bolus obstruction (AFBO) was carried out on 17 consecutive patients who presented with this complaint. There were nine males and eight females. Twelve patients (71 per cent) had symptoms of oesophageal disease and 10 patients (59 per cent) had prior food bolus obstruction. Investigations included endoscopy, barium swallow, oesophageal pH and manometry studies. Evidence of oesophageal pathology was found in 12/14 (86 per cent) of patients investigated. No patients had malignancy and the most common abnormality, gastroesophageal reflux (GOR) was found in eight out of 14 (57 per cent) of cases. Oesophageal dysmotility was seen in five out of 12 (42 per cent) patients who had manometric studies. With such a high incidence of recurrence of AFBO, we suggest that patients with this condition be investigated to exclude malignancy and to identify benign oesophageal pathology using techniques such as oesophageal pH and manometry. Appropriate treatment of oesophageal disease may help prevent recurrence of this distressing condition.

The effect of tonsillectomy on eustachian tube function

A two-part study was designed to investigate the effect of tonsillectomy on eustachian tube function and to identify if any change is related to postoperative pain. Middle ear pressure was measured by tympanometry and results were classified as type A (+50 daPa to -99 daPa), type B (flat) or type C (-100 daPa to -350 daPa). Thirty-one patients with type A tympanograms, undergoing tonsillectomy enrolled in study A. Patients had tympanometry the next day and filled in a questionnaire incorporating visual analogue pain scores. In study B, 30 patients underwent a similar protocol and were followed up at 1 week tympanometry and a questionnaire. A control group of 26 patients undergoing appendicectomy was recruited. Follow-up was available on 23 patients from study B. Combining A and B, on the first postoperative day 39% of patients developed type C tympanograms. No member of the control group developed any change in middle ear pressure. There was no significant relationship between pain scores for throat pain or otalgia and the development of negative middle ear pressure. By day 7 all patients had type A tympanograms. Otalgia was a delayed symptom significantly associated with increased throat pain. Transient negative middle ear pressure commonly occurs following tonsillectomy.

Tonsillitis, tonsillectomy and weight disturbance

To determine the relationship between tonsillitis, tonsillectomy and abnormalities in body weight, we have analyzed pre- and post-operative weights in a population of 55 children who underwent adenotonsillectomy in our department. Pre-operative mean weight was 9.8% heavier than the standard mean normal weight for age and post-operative mean weight was 22% greater than standard mean weight for age. The mean weight gain during the follow-up period was 12% greater than that which would be normally expected (p < 0.001). This study suggests that children undergoing tonsillectomy are slightly heavier than their peers and that following the procedure this discrepancy increases.

Improvements in health and behaviour following childhood tonsillectomy: a parental perspective at 1 year

To determine subjective parental impressions following routine tonsillectomy we have interviewed the parents of 80 children 1 year following the procedure. Results show that the procedure carried a 100% parental satisfaction rating. All parents felt their child's symptoms of recurrent acute tonsillitis had improved and over 90% of parents felt their child's general health had improved. Sixty-four percent of the parent population reported a noticeable improvement in their child's sleeping pattern and over 30% described an improvement in their child's general behavior. Although this study reports subjective data, and we do not have a comparable control population, these findings provide an interesting insight into parental impressions regarding alterations in their child's health, sleep pattern and behaviour following this procedure.

Clearance of recalcitrant psoriasis after tonsillectomy

Infection is a well-recognized triggering factor for both guttate and chronic plaque psoriasis. We investigated prospectively 13 patients with recalcitrant psoriasis exacerbated by recurrent tonsillitis, who underwent tonsillectomy between 1990 and 1993. There were 12 female patients and one male, with a mean age of 17 yr (range 6-28). Six patients had guttate psoriasis resistant to standard treatments and seven patients had chronic plaque psoriasis exacerbated by tonsillitis that was severe enough to warrant at least one admission to hospital. Patients were followed by chart review and postal questionnaire. Psoriasis was cleared completely after tonsillectomy in five out of the six patients (83%) with guttate psoriasis and was improved in one patient. Two out of seven patients with plaque psoriasis (29%) were cleared, two (29%) were improved and three (42%) were unchanged. We conclude that tonsillectomy may be a successful treatment modality in selected patients with recalcitrant guttate or chronic plaque psoriasis.

Examining the ear: clinical teaching

Although otolaryngology represents up to 20% of the workload of general practitioners, the time allocated in the undergraduate medical curriculum to clinical teaching of ENT disorders is disproportionately small. Many GPs have indicated a desire for further training in ENT, particularly in small groups. This study was carried out on a group of 27 GPs who wished to revise their diagnostic skills in otoscopy by attending a 2-hour teaching session on basic examination of the ear and the recognition and management of common otological conditions. The GPs skill in otoscopy before and after the course was assessed subjectively by means of a self-administered questionnaire and scored objectively by ENT surgeons. Aspects of otoscopy chosen for assessment were technique of examination of the external ear, choosing correct speculum size, techniques of holding the otoscope and pinna, tympanic membrane description and diagnostic ability. An improvement between the objective pre- and post-workshop scores was found for assessment of the external ear, choice of speculum size, description of the tympanic membrane and diagnostic ability. No significant differences in the pre- and post-workshop scores was found for the techniques of holding the otoscope or holding the pinna. The majority of the GPs found the workshop beneficial. Postgraduate teaching of specialist diagnostic skills such as otoscopy to GPs is useful. An improvement in such skills should enable the GPs to manage ENT problems more confidently and refer patients appropriately to the ENT outpatients.

The role of IGFBP-3 in the regulation of IGFBP-4 proteolysis

The biological effects of insulin-like growth factors (IGFs) are mediated by cell surface receptors but their bioavailability is regulated by IGF binding proteins (IGFBPs) which bind IGF with higher affinity than the receptor. Proteolytic cleavage of the binding proteins reduces their affinity for IGF making the IGF more available to the cell receptor. In the current study we have examined the regulation of IGFBP-4 protease produced by cultured human dermal fibroblasts. IGF-I and the analogs of IGF-I (LR3 and Des[1-3]) induced a dose dependent increase in both proliferation and IGFBP-3 production. Low concentrations of IGF-I induced a marked loss of IGFBP-4 by Western ligand blotting (WLB). This effect was confirmed by the ability of media collected from cells exposed to increasing concentrations of IGF-I to fragment recombinant IGFBP-4, an effect blocked by EDTA. IGFBP-4 proteolysis was observed when cells were exposed to Des[1-3] (albeit at higher concentrations) but not with LR3. Both analogs bind to the IGF receptor but do not bind to IGFBP-4 and have reduced (Des[1-3]) or no (LR3) affinity for IGFBP-3. This demonstrated that neither receptor activation nor ligand binding directly to IGFBP-4 was necessary for IGF induced proteolysis. Protease activity correlated with affinity for IGFBP-3 suggesting a role for IGFBP-3 in the regulation of IGFBP-4 proteolysis. This was confirmed by the ability of excess recombinant IGFBP-3 to inhibit the IGF-I and Des[1-3] induced proteolysis of IGFBP-4. Addition of IGF-I to media from cells unexposed to IGF induced IGFBP-4 proteolysis but this was not seen with LR3 which does not bind to IGFBP-3. Fragmentation occured at higher concentrations of Des[1-3] consistent with its reduced affinity for IGFBP-3. This data suggests that IGFBP-4 proteolysis is regulated in a novel manner by IGFBP-3 which is dependent on the relative proportions of the different binding proteins and the levels of IGFs.

A twenty year (1971-1990) review of tracheostomies in a major paediatric hospital

Changing trends in the indications for paediatric tracheostomies, with decreasing numbers of tracheostomies being performed, have been reported in the literature. In a retrospective analysis of the period 1971 to 1990 the experience of tracheostomies in children under the age of 15 at Our Lady's Hospital (Dublin) is reviewed. Only 29 tracheostomies were performed during this time with an increase in numbers (90%) performed during the second 10 year period. The major underlying indication for tracheostomy in both 10 year periods was for the management of an airway problem secondary to congenital abnormalities (65%). In 14 children the operation was performed during the first year of life. However, while 90% of the children were under the age of one in the period 1971-1980 this fell to 26% during 1981-1990. Complications occurred in 41% overall, however, in the under 1 year old group 64% developed complications. There were no deaths as a direct result of the tracheostomy or its complications, but six children died because of the severity of the underlying disease. The average length of time before decannulation was 2.1 years, with decannulation difficulties occurring infrequently (11%).

[Dysphonia and inhalation of corticoids: a prospective study]

Dysphonia or hoarseness is a well recognised but poorly understood complication of inhaled steroid therapy. 20 asthmatics were investigated, using a perceptual rating score of hoarseness, videolaryngoscopy and videostroboscopy, prior to and after three months of high dose inhaled steroid therapy (1 mg/day). A group of 22 healthy volunteers acted as controls. Prior to commencing inhaled steroid therapy six of the asthmatics were hoarse. Erythema and oedema was noted in 10 asthmatics and vocal fold nodules in 2 asthmatics. 4 of the control group had erythema and oedema. There was significantly more vocal fold pathology in the asthmatic group, p = 0.0135. After three months of inhaled steroid therapy, improvement in voice was noted in 2 of the 6 hoarse asthmatics. This was associated with resolution of vocal fold nodules in one case and with resolution of oedema in another. One asthmatic developed a mid glottic chink. This study demonstrates that asthmatics have significantly more vocal fold pathology than healthy controls. These findings improve with commencement of inhaled steroid therapy. The development of steroid induced myopathy of the vocal folds is a possible cause for the development of a mid glottic chink in one of our subjects. Further studies are necessary to investigate this area further.

Investigations on a curved intracochlear array

A curved electrode array and inserting tool have been developed at the University of Melbourne. This electrode array can be successfully implanted with few modifications to the surgical procedure presently in use. When implanted, the curved electrode array adopts a position closer to the modiolus than does the standard straight electrode array.

Chronic middle ear disease and cochlear implantation

We have presented three patients with bilateral CSOM who were otherwise suitable for cochlear implantation. These patients had conventional surgical management of CSOM and were implanted after a period of 6 months through apparently healthy middle ears. However, all three had a recurrence of middle ear disease requiring further surgery, and one had a potentially life-threatening complication necessitating removal of the implant. Before considering cochlear implantation in patients with bilateral CSOM, it is essential to eradicate all disease, and radical mastoidectomy with obliteration may be necessary. The use of a cochlear sealing device may further ensure prevention of infection spreading into the cochlea.

Initial investigation of the efficacy and biosafety of sodium hyaluronate (Healon) as an aid to electrode array insertion

Sodium hyaluronate has potential uses as an electrode lubricant in cochlear implant surgery. Deeper electrode insertions were achieved in six temporal bones implanted with sodium hyaluronate, compared to 22 patients implanted without sodium hyaluronate. Preliminary biosafety studies measuring hearing thresholds of six cats 4 months after implantation with dummy electrodes did not show evidence of ototoxicity caused by sodium hyaluronate. Until the biosafety studies are complete, we cannot recommend sodium hyaluronate for routine use, but the results so far are promising.

ENT and general practice: a study of paediatric ENT problems seen in general practice and recommendations for general practitioner training in ENT in Ireland

A questionnaire survey of 225 general practitioners was carried out to establish the proportion of their workload formed by paediatric ENT problems. Approximately 50% of children seeking medical care from their general practitioners had problems in this area. Infections of the upper respiratory tract and associated organs were the most commonly dealt with complaints. The monthly referral rate by GPs of paediatric patients in their practice to an ENT outpatient clinic was 4.3%. As ENT problems are seen so commonly in general practice it is important that teaching of otolaryngology at undergraduate and postgraduate levels is emphasised. We examined the present teaching structure of ENT in Irish universities and established that the appointment of a professorial unit dramatically improved the extent of the undergraduate curriculum. Non-specialist postgraduate ENT exposure was found to be inadequate and a number of mechanisms to improve postgraduate ENT training for GPs are suggested.