Accounting for the spatial rainfall variability in urban modelling applications

In hydrological and hydrodynamic modelling of urban catchments, the spatial variability of rainfall is often neglected. This spatial variability encloses two aspects: (1) the spatial variability of the statistical properties of rainfall, and (2) the non-uniform spatial distribution of rainfall over the modelled catchments. In an ongoing research project for the Ministry of the Flemish Community (Belgium), the influence of this spatial rainfall variability on the results of modelling applications is studied. At the same time, most efficient methods to reduce this influence are determined. The results of the research can be applied directly in Flanders. They consist of a combination of unified IDF-relationships, spatial correction factors (generally applicable formulas), a stochastic simulation model for spatial rainfall (software) and a methodology for improving the spatial correction factors in a case-specific way by performing simulations with the model.

Modeling of nitrogen in river water using a detailed and a simplified model

To model catchment surface water quantity and quality, different model types are available. They vary from detailed physically based models to simplified conceptual and empirical models. The most appropriate model type for a certain application depends on the project objectives and the data availability. The detailed models are very useful for short-term simulations of representative events. They cannot be used for long-term statistical information or as a management tool. For those purposes, more simplified (conceptual or meta-) models must be used. In this study, nitrogen dynamics are modeled in a river in Flanders. Nitrogen sources from agricultural leaching and domestic point sources are considered. Based on this input, concentrations of ammonium (NH4-N) and nitrate (NO3-N) in the river water are modeled in MIKE 11 by taking into consideration advection and dispersion and the most important biological and chemical processes. Model calibration was done on the basis of available measured water quality data. To this detailed model, a more simplified model was calibrated with the objective to more easily yield long-term simulation results that can be used in a statistical analysis. The results show that the conceptual simplified model is 1800 times faster than the MIKE 11 model. Moreover the two models have almost the same accuracy. The detailed models are recommended for short-term simulations unless there are enough data for model input and model parameters. The conceptual simplified model is recommended for long-term simulations.

A new combined DTP-HBV-Hib vaccine--strategy for incorporation of Hib vaccination into childhood immunisation programmes

OBJECTIVES

To evaluate the immunogenicity and reactogenicity of a pentavalent vaccine prepared by extemporaneously mixing diphtheria-tetanus pertussis-hepatitis B vaccine (DTP-HBV) and lyophilised Haemophilus influenzae type B (Hib)-tetanus conjugate vaccines in the same syringe, compared with the same vaccines given as separate, concomitant administrations.

DESIGN

Open, randomised comparative study.

SETTING

Durban, South Africa.

SUBJECTS

A total of 120 healthy male and female infants were enrolled in the trial and randomised into two groups; group 1 received the combined administration (DTP-HBV-Hib), and group 2 received separate administrations of DTP-HBV and Hib vaccines. Vaccines were given as a three-dose primary vaccination course at 2, 4 and 6 months [corrected] of age.

OUTCOME MEASURES

Antibody levels were measured using standard techniques and local and general solicited symptoms were recorded using diary cards.

RESULTS

All subjects had seroprotective titres against diphtheria and tetanus; and antipolyribose-ribitol phosphate (PRP) titres > or = 0.15 microgram/ml 1 month after the final dose. A vaccine response (defined as post-vaccination titres > or = 15 ELISA (EL).U/ml in initially seronegative subjects; and as post-vaccination titres > or = pre-vaccination titres in initially seropositive subjects) against the pertussis component was seen in 83% and 85% of subjects in the groups receiving combined and separate administration. No differences were seen in any of the geometric mean titres (GMTs) between the two administrations either 2 months after the second dose or 1 month after the final dose. There was no observed increase in reactogenicity in the group receiving the mixed administration.

CONCLUSIONS

The results demonstrate that combined DTP-HBV-Hib vaccine is well tolerated and immunogenic.

Limb-body wall complex: 4 new cases illustrating the importance of examining placenta and umbilical cord

Limb-body wall complex (LBWC) is a rare, sporadic, congenital defect defined as a combination of at least two of three characteristics: 1. limb defects, 2. anterior body wall defects, and 3. exencephaly or encephalocoele with/without facial clefts. Three pathogenic mechanisms have been proposed: early amnion rupture, vascular disruption and embryonic dysgenesis. In this study we carried out the pathological evaluation of four fetuses with LBWC and their placentas. None of the cases had craniofacial defects. Three fetuses showed an abdominal wall defect with eventration of abdominal organs, cloacal exstrophy, absent external genitalia, abnormal internal genitalia, scoliosis and lower limb defects. One fetus showed failure of closure of both thoracic and abdominal walls with ectopia cordis, evisceration of left lung and abdominal organs, severe reduction defect of left arm, but normal colon, anus, bladder, genitalia and lower limbs. All cases had a short, malformed umbilical cord, incompletely covered by amnion. The umbilical vessels were embedded in an amniotic sheet which connected the skin margin of the anterior body wall defect to the placenta. These anomalies suggest an abnormal body stalk development as a pathogenic mechanism for LBWC. Prenatally, the abnormal fetoplacental attachment can be detected ultrasonographically by the end of the first gestational trimester. Postnatally, the examination of placenta, umbilical cord and membranes is crucial in confirming the diagnosis of LBWC.

Increased bone density in sclerosteosis is due to the deficiency of a novel secreted protein (SOST)

Sclerosteosis is a progressive sclerosing bone dysplasia with an autosomal recessive mode of inheritance. Radiologically, it is characterized by a generalized hyperostosis and sclerosis leading to a markedly thickened and sclerotic skull, with mandible, ribs, clavicles and all long bones also being affected. Due to narrowing of the foramina of the cranial nerves, facial nerve palsy, hearing loss and atrophy of the optic nerves can occur. Sclerosteosis is clinically and radiologically very similar to van Buchem disease, mainly differentiated by hand malformations and a large stature in sclerosteosis patients. By linkage analysis in one extended van Buchem family and two consanguineous sclerosteosis families we previously mapped both disease genes to the same chromosomal 17q12-q21 region, supporting the hypothesis that both conditions are caused by mutations in the same gene. After reducing the disease critical region to approximately 1 Mb, we used the positional cloning strategy to identify the SOST gene, which is mutated in sclerosteosis patients. This new gene encodes a protein with a signal peptide for secretion and a cysteine-knot motif. Two nonsense mutations and one splice site mutation were identified in sclerosteosis patients, but no mutations were found in a fourth sclerosteosis patient nor in the patients from the van Buchem family. As the three disease-causing mutations lead to loss of function of the SOST protein resulting in the formation of massive amounts of normal bone throughout life, the physiological role of SOST is most likely the suppression of bone formation. Therefore, this gene might become an important tool in the development of therapeutic strategies for osteoporosis.

Nutritional lipid emulsions modulate cellular signaling and activation of human neutrophils

Although numerous studies suggest that nutritional lipids modulate human immune responses, the mechanism behind this observation remains unclear. On the basis of the hypothesis that lipids might affect cellular signaling we evaluated the effects of various lipid emulsions on two major pathways involved in neutrophil activation: second messenger (Ca(2)+) mobilization and protein kinase C (PKC) activation. Activation by opsonized yeast particles (serum-treated zymosan; STZ) increased cytosolic [Ca(2)+] ([Ca(2)+](i)) in neutrophils, with an initial slow rise that turned into a fast phase until a plateau was reached. The PKC activator 4-alpha-phorbol 12-myristate 13-acetate (PMA) markedly increased the initial STZ-induced [Ca(2)+](i) rise. This PMA effect was mimicked by emulsions containing medium-chain triglycerides (MT), but not by long-chain triglycerides (LT) or structured lipids (SL). However, like PMA, all emulsions decreased the STZ-induced [Ca(2)+](i) plateau and all activated purified PKC, suggesting that only MT emulsions activate PKC in the context of the intact cell. MT, like PMA, evoked a leftward shift of the dose-response curve for the STZ-induced [Ca(2)+](i) rise, indicating PKC-dependent sensitization of neutrophils for stimulation by STZ. This study is the first to show that nutritional lipids distinctively modulate cellular signaling and stimulation of neutrophils through effects on calcium mobilization and PKC activation: i) MT emulsions sensitize neutrophils for STZ in a PKC-dependent manner, and ii) MT, LT, and SL emulsions all reduce the stimulatory effect of STZ in a nonspecific manner. -- Wanten, G., S. van Emst-de Vries, T. Naber, and P. Willems. Nutritional lipid emulsions modulate cellular signaling and activation of human neutrophils. J. Lipid Res. 2001. 42: 428--436.

A new DTPa-HBV-IPV vaccine co-administered with Hib, compared to a commercially available DTPw-IPV/Hib vaccine co-administered with HBV, given at 6, 10 and 14 weeks following HBV at birth

Three hundred and twenty eligible infants were enrolled in an open randomized clinical trial and allocated to one of two groups to receive either separate concomitant injections of a candidate combined DTPa-HBV-IPV and commercial Hib vaccine (candidate administration: DTPa-HBV-IPV+Hib) or separate concomitant injections of licensed DTPw-IPV mixed in the same syringe with Hib and HBV vaccines (comparator administration: DTPw-IPV/Hib+HBV). Vaccines were administered at 6, 10 and 14 weeks of age preceded by a monovalent dose of HBV at birth. The candidate vaccine administration was shown to be at least as immunogenic (primary objective) as the candidate administration with respect to the diphtheria, tetanus, polio, HBs and PRP seroprotection rates (primary endpoints). Post vaccination, both vaccine administrations showed an equivalent level of seroprotection with nearly all subjects (>96%) acquiring seroprotective titers against diphtheria, tetanus, polioviruses, HBsAg and PRP antigens. A markedly higher anti-HBs response post dose 2 at week 14 in the group receiving the candidate vaccine, 98.6% of subjects had seroprotective titers (GMT of 505.7 mIU/ml) compared with only 88.7% (GMT of 107.5 mIU/ml) in the comparator group. There was a lower incidence of adverse events following the DTPa-based candidate administration compared with the DTPw-based comparator. Despite the early age and short interval between doses, both administrations were immunogenic, with the concomitant administration of DTPa-HBV-IPV and Hib vaccines showing an improved tolerability over the commercial vaccines DTPw-IPV/Hib and HBV.

Protein kinase C alpha controls erythropoietin receptor signaling

Protein kinase C (PKC) is implied in the activation of multiple targets of erythropoietin (Epo) signaling, but its exact role in Epo receptor (EpoR) signal transduction and in the regulation of erythroid proliferation and differentiation remained elusive. We analyzed the effect of PKC inhibitors with distinct modes of action on EpoR signaling in primary human erythroblasts and in a recently established murine erythroid cell line. Active PKC appeared essential for Epo-induced phosphorylation of the Epo receptor itself, STAT5, Gab1, Erk1/2, AKT, and other downstream targets. Under the same conditions, stem cell factor-induced signal transduction was not impaired. LY294002, a specific inhibitor of phosphoinositol 3-kinase, also suppressed Epo-induced signal transduction, which could be partially relieved by activators of PKC. PKC inhibitors or LY294002 did not affect membrane expression of the EpoR, the association of JAK2 with the EpoR, or the in vitro kinase activity of JAK2. The data suggest that PKC controls EpoR signaling instead of being a downstream effector. PKC and phosphoinositol 3-kinase may act in concert to regulate association of the EpoR complex such that it is responsive to ligand stimulation. Reduced PKC-activity inhibited Epo-dependent differentiation, although it did not effect Epo-dependent "renewal divisions" induced in the presence of Epo, stem cell factor, and dexamethasone.

Consensus strategy to quantitate malignant cells in myeloma patients is validated in a multicenter study. Belgium-Dutch Hematology-Oncology Group

Recently the Belgium-Dutch Hematology-Oncology group initiated a multicenter study to evaluate whether myeloma patients treated with intensive chemotherapy benefit from additional peripheral stem cell transplantation. To determine treatment response accurately, we decided to quantitate malignant cells. To test a consensus quantitation strategy, 5 centers independently determined the immunoglobulin heavy chain sequences of patient tumor cells and developed allele-specific oligonucleotides (ASO) and ASO-polymerase chain reaction (PCR). We compared the reproducibility of real-time quantitation with quantitation using limiting dilutions. We distributed DNA samples with a 4-log range of tumor cell concentrations and found average quantitation values deviating 74% and 42% from the input values with real-time PCR (1 center) and limiting dilutions (4 centers), respectively. Within single centers we found an average variation coefficient of 0.74, with limiting dilutions not significantly different from the average 0.82 center-to-center variation coefficient. Within a single center, real-time quantitation proved more reproducible (average variation coefficient, 0.36). Quantification was confirmed in 3 patients during treatment in the protocol. This report shows that real-time PCR or limiting dilution assays can be used for quantitation in a single multicenter trial. We present a consensus strategy that allows an accurate comparison of quantitation data generated in independent centers.

A new needle-crystalline computed radiography detector

The most successful digital radiography detectors to date have been storage phosphor plates used in computed radiography (CR). The detector is cheap, has good producibility, and is robust. Direct radiography (DR) systems are being developed based on flat-panel technology. Better image quality is claimed for some DR systems. On the other hand, DR detectors have low producibility and robustness, and a high price. A new CR detector is being developed at Agfa that combines the advantages of CR and DR. It is a storage phosphor plate made up of needle-shaped crystals. The phosphor efficiently converts absorbed x-ray quanta into photostimulable centers for efficient read out. It has a large dynamic range and its emission is efficiently detected with both photomultiplier tube (PMT) and charge coupled device (CCD). It is shown that CR systems based on the new detector offer image quality that matches that of the best DR systems.

Control of rapid aimed hand movements: the one-target advantage

A series of 8 experiments examined the phenomenon that a rapid aimed hand movement is executed faster when it is performed as a single, isolated movement than when it is followed by a second movement (the 1-target advantage). Three new accounts of this effect are proposed and tested: the eye movement hypothesis, the target uncertainty hypothesis, and the movement integration hypothesis. Data are reported that corroborate the 3rd hypothesis, but not the first 2 hypotheses. According to the movement integration hypothesis, the first movement in a series is slowed because control of the second movement may overlap with execution of the first. It is shown that manipulations of target size and movement direction mediate this process and determine the presence and absence of the 1-target advantage. Possible neurophysiological mechanisms and implications for motor control theory are discussed.

Safety and immunogenicity of combined Dtpa-IPV vaccine for primary and booster vaccination

This study evaluated the safety and immunogenicity of combined diphtheria, tetanus, acellular pertussis, inactivated poliomyelitis vaccine (DTPa-IPV) given as primary immunization at ages 3, 4.5 and 6 months and a booster dose between the ages of 18 and 27 months to healthy children. The acellular pertussis tricomponent vaccine contains pertussis toxoid (PT), filamentous haemaglutinin (FHA) and 69 kDa outer membrane protein (PRN). Serum immune responses to the administered antigens were measured before and after the primary and the booster vaccination series. The safety of the vaccine was evaluated based on diary cards completed by parents within 4 d following each vaccination. A total of 237 and 150 children completed the primary and booster vaccination series, respectively. A total of 483 (66.5%) and 111 (74%) local and 317 (43.7%) and 98 (65.3%) general adverse events were reported after 726 doses of the primary series and 150 of the booster doses, respectively. Compared with primary vaccination, the incidence of all adverse symptoms was greater after the booster dose and a previous severe reaction was a risk factor for a severe reaction after the booster dose (OR = 5.11). All but 1 child, who failed to have antibodies to diphtheria toxoid after the booster dose, responded to all administered antigens with antibody titres greater than the assay cut-off points. The combined DTPa-IPV used for primary and booster immunization induced good immunity, but was associated with large local reactions in 21.3% of children after the booster dose.

Control of rapid aimed hand movements: the one-target advantage

A series of 8 experiments examined the phenomenon that a rapid aimed hand movement is executed faster when it is performed as a single, isolated movement than when it is followed by a second movement (the 1-target advantage). Three new accounts of this effect are proposed and tested: the eye movement hypothesis, the target uncertainty hypothesis, and the movement integration hypothesis. Data are reported that corroborate the 3rd hypothesis, but not the first 2 hypotheses. According to the movement integration hypothesis, the first movement in a series is slowed because control of the second movement may overlap with execution of the first. It is shown that manipulations of target size and movement direction mediate this process and determine the presence and absence of the 1-target advantage. Possible neurophysiological mechanisms and implications for motor control theory are discussed.

Comparison study of combined DTPw-HB vaccines and separate administration of DTPw and HB vaccines in Thai children

The safety, immunogenicity and tolerability of two different DTPw-HBV combination vaccines, containing 5 and 10 microg of HBsAg; were investigated in comparison with separate administration of DTPw and HBV (10 microg of HBsAg). A three dose primary vaccination course at 2, 4 and 6 months of age was followed by a booster dose at 18 months. All vaccines were safe and well tolerated. The DTPw-HBV combination vaccine containing 10 microg of HBsAg elicited significantly higher anti-HBs titres than the other two vaccines after the primary and booster vaccination course. All vaccines elicited a high response against the other components. Based on these results, DTPw-HBV (10 microg HBsAg) was the most effective vaccine at this schedule.

Safety and immunogenicity of Haemophilus influenzae-tetanus toxoid conjugate vaccine given separately or in combination with a three-component acellular pertussis vaccine combined with diphtheria and tetanus toxoids and inactivated poliovirus vaccine for the first four doses

The purpose of this randomized, controlled trial was to assess the safety and immunogenicity of a three-component acellular pertussis vaccine combined with diphtheria and tetanus toxoids and inactivated poliovirus vaccine given either separately or combined as a single injection with a Haemophilus influenzae type b-tetanus toxoid conjugate vaccine. A total of 180 infants were immunized at 2, 4, and 6 months of age; 129 were given a booster dose at 16-19 months of age. Vaccine-associated adverse events were similar whether the vaccines were combined as a single injection or given separately. There were no differences in levels of antibodies to Bordetella pertussis antigens (pertussis toxoid, filamentous hemagglutinin, and pertactin), diphtheria toxoid, or the three poliovirus types. The tetanus antitoxin level after the primary three-dose series was higher in recipients of the combined vaccine (2.37 IU/mL) than in recipients of the separate injections (1.32 IU/mL; two-sided P = .0001). In contrast, combined vaccine recipients had lower levels of antibody to H. influenzae type b polysaccharide after the third dose (1.57 microg/mL) than did those given separate injections (3.22 microg/mL; two-sided P = .0026). The antibody levels were not significantly different before or 1 month after the booster dose (32.9 microg/mL vs. 47.8 microg/mL, respectively; two-sided P = .07). We conclude that the vaccines were immunogenic and well tolerated. Despite lower levels of antibody to the H. influenzae type b polysaccharide after the primary three-dose series, mixing of the vaccines in a single syringe likely induced immunologic priming, as suggested by the high antibody levels after the booster dose.

The new DTPw-HBV-Hib combination vaccine can be used at the who schedule with a monovalent dose of hepatitis B vaccine at birth

An open, randomized, clinical trial was conducted in order to assess the reactogenicity and immunogenicity of DTPw-HBV and Haemophilus influenzae type b (Hib) vaccines when given either as a mixed administration or as separate concomitant injections using the WHO schedule at 6, 10 and 14 weeks of age, following a dose of HBV at birth. There were no clinically relevant differences in the immune response to any component between the mixed and separate administrations. In fact the anti-tetanus GMTs were significantly higher (p=0.002) in mixed administration (3.9 IU/ml) compared with the separate administration (1.9 IU/ml). However although all subjects achieved anti-PRP titers > or = 0.15 microg/ml, higher anti-PRP GMTs were seen in the group receiving the separate administration. Importantly, the addition of Hib did not adversely alter the reactogenicity profile of DTPw-HBV. This report which demonstrates that this novel combination can be used in WHO recommended schedule.

Clinical, biochemical and molecular findings in a patient with X-linked liver glycogenosis followed for 40 years

Phosphorylase kinase (PHK) is a regulatory enzyme in glycogen metabolism. Mutations in the gene encoding the alpha subunit of PHK (PHKA2) have been shown to be responsible for X-linked liver glycogenosis (XLG). XLG, a frequent type of glycogen storage disease, is characterised by hepatomegaly and growth retardation. Two subtypes of XLG have been described: XLG type I patients have a clear-cut PHK deficiency in liver and blood cells, whereas XLG type II patients have a normal or residual activity. Here, we present clinical, biochemical and molecular findings on a liver glycogenosis patient in whom the diagnosis XLG II only became clear after enzyme assays in the liver and identification of the disease-causing mutation. A missense mutation replacing arginine at amino acid position 186 by histidine (R186H) was identified in the PHKA2 gene. Mutations of the same arginine residue have been previously found in at least four other unrelated XLG II patients.

CONCLUSION

Arginine at position 186 of the alpha subunit seems to play an important role in the structure or the regulation of PHK. In patients with XLG having normal or residual PHK activity where XLG II is suspected, the identification of mutations in PHKA2 leads to the final classification.

Sporadic imprinting defects in Prader-Willi syndrome and Angelman syndrome: implications for imprint-switch models, genetic counseling, and prenatal diagnosis

The Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) are caused by the loss of function of imprinted genes in proximal 15q. In approximately 2%-4% of patients, this loss of function is due to an imprinting defect. In some cases, the imprinting defect is the result of a parental imprint-switch failure caused by a microdeletion of the imprinting center (IC). Here we describe the molecular analysis of 13 PWS patients and 17 AS patients who have an imprinting defect but no IC deletion. Heteroduplex and partial sequence analysis did not reveal any point mutations of the known IC elements, either. Interestingly, all of these patients represent sporadic cases, and some share the paternal (PWS) or the maternal (AS) 15q11-q13 haplotype with an unaffected sib. In each of five PWS patients informative for the grandparental origin of the incorrectly imprinted chromosome region and four cases described elsewhere, the maternally imprinted paternal chromosome region was inherited from the paternal grandmother. This suggests that the grandmaternal imprint was not erased in the father's germ line. In seven informative AS patients reported here and in three previously reported patients, the paternally imprinted maternal chromosome region was inherited from either the maternal grandfather or the maternal grandmother. The latter finding is not compatible with an imprint-switch failure, but it suggests that a paternal imprint developed either in the maternal germ line or postzygotically. We conclude (1) that the incorrect imprint in non-IC-deletion cases is the result of a spontaneous prezygotic or postzygotic error, (2) that these cases have a low recurrence risk, and (3) that the paternal imprint may be the default imprint.

Paget's disease of bone: evidence for a susceptibility locus on chromosome 18q and for genetic heterogeneity

Paget's disease of bone is a common condition characterized by bone pain, deformity, pathological fracture, and an increased incidence of osteosarcoma. Genetic factors play a role in the pathogenesis of Paget's disease but the molecular basis of the disease remains unclear. Previous genetic linkage studies have mapped the rare Paget's disease-like bone dysplasia familial expansile osteolysis (FEO) to chromosome 18q21-22, and recent work has shown evidence of linkage between this locus and Paget's disease in one family. Here we studied the relationship between the 18q21-22 locus and Paget's disease in eight large multiplex families from diverse ethnic backgrounds with inherited Paget's disease. Paget's disease was inherited as an autosomal dominant trait in all families, with high penetrance by the sixth decade. Analysis of seven highly polymorphic markers from chromosome 18q21-22 showed positive summated two-point log10 odds ratio (lodscores) of +2.97 with the marker D18S42 at a recombination fraction (theta) = 0.05, and of +2.95 with the marker D18S60 at theta = 0.00, values which are close to the cut-off of +3.0, which is generally accepted as evidence of linkage. Segregation analysis of the haplotypes and formal statistical analysis using the HOMOG program provided evidence for genetic heterogeneity, however, with evidence for linkage in five families and against linkage in the remaining three families (chi square 8.82; df = 2; p < 0.025). Multipoint linkage analysis in the five linked families showed lodscores of above +3.5 across the whole susceptibility region and a maximum summated lodscore of 3.89 at the marker D18S465. In the three nonlinked families, negative multipoint results were obtained for the whole region, with lodscores below -2.0 in one family, excluding this as a candidate locus for the disease. Our studies demonstrate the importance of hereditary factors in the pathogenesis of Paget's disease and confirm evidence of linkage between Paget's disease and chromosome 18q21-22 in some families. This raises the possibility that Paget's disease and FEO may share a common molecular basis, perhaps due to different mutations in the same gene or family of genes. Data from three families did not support evidence of linkage to 18q21-22 however, indicating that Paget's disease is genetically heterogeneous and suggests the presence of at least one additional locus which remains to be discovered.

Nonsyndromic autosomal dominant progressive sensorineural hearing loss: audiologic analysis of a pedigree linked to DFNA2

An analysis was performed of the regression of the individual hearing threshold on age in the affected persons in a six-generation Dutch family with nonsyndromic autosomal dominant sensorineural hearing loss, which showed linkage to the DFNA2(1p34) region, similar to at least four previously reported nonrelated families. The offset threshold was significantly higher at the high frequencies (around 30 dB at 2 to 8 kHz) than at the lower ones (approximately 0 dB at 0.25 to 1 kHz). Hearing impairment at the higher frequencies may therefore have been present already at birth or in early childhood. The regression coefficient, or the 'annual threshold increase,' expressed in dB/y, was about 1 dB/y on average, but the higher frequencies (1 to 8 kHz) showed significantly more rapid progression than the lower frequencies (0.25 to 0.5 kHz).

Safety and immunogenicity of a combined pentavalent diphtheria, tetanus, acellular pertussis, inactivated poliovirus and Haemophilus influenzae type b-tetanus conjugate vaccine in infants, compared with a whole cell pertussis pentavalent vaccine

BACKGROUND

We compared the safety and immunogenicity of two combined diphtheria-tetanus-pertussis-inactivated poliovirus vaccines containing either acellular (Pa, SmithKline Beecham Biologicals) or whole cell (Pw, Pasteur Merieux Connaught) pertussis components, mixed with a Haemophilus influenzae type b polysaccharide polyribosylribitol phosphate-tetanus conjugate vaccine in an open, randomized study in healthy infants.

DESIGN

The combined vaccines were given at 2, 4, 6 and 12 months of age, and serum samples were obtained at ages 2, 6, 7, 12 and 13 months. Adverse events were obtained by diary cards.

RESULTS

The Pa group (n = 101) had a clearly lower incidence of both local and systemic adverse events than the Pw group (n = 100). Immunogenicity was comparable for the diphtheria and tetanus components, but significantly superior for pertussis toxin, filamentous hemagglutinin, pertactin and polioviruses 1, 2 and 3 in the Pa group. Both groups had an appropriate response with regard to H. influenzae type b polysaccharide polyribosylribitol phosphate, but the dynamics of the response were significantly different: geometric mean concentrations (micrograms per ml) after the second, third and booster doses were 1.27, 5.06 and 23.12 in the Pa group and 2.72, 6.66 and 13.59 in the Pw group, respectively (P = 0.0002 after second dose; P = 0.0005 after booster).

CONCLUSION

The presently studied diphtheria, tetanus, acellular pertussis-H. influenzae b vaccine conjugated to tetanus toxoid combination was at least as immunogenic as the diphtheria, tetanus, whole cell pertussis-H. influenzae b vaccine conjugated to tetanus toxoid combination, with a significantly better safety profile. This is of obvious importance in countries where inactivated poliovirus vaccine is part of the routine infant immunization programs.

Does walking speed influence the time pattern of muscle activation in normal children?

Dynamic electromyography (EMG) of the extrinsic muscles of the ankle is used more and more frequently to assist in the planning of tendon transfers in children with equinovarus deformities. Since these children walk at low speeds (1 to 4km/h), and since walking speed modifies the EMG-time pattern, the clinical investigator must be able to differentiate EMG modifications due to pathology versus those due to slow walking speed. The aim of this work was to study the effect of walking speed on the EMG-time pattern of the extrinsic ankle muscles in healthy children between 4 and 11 years of age. This pattern was found to change significantly with speed of progression but is independent of growth over this age range. A nomograph of EMG timing, taking into account walking speed, is proposed for clinical gait analysis.