Sonographic evaluation of hip effusion in children. Improved visualization with the hip in extension and abduction

PURPOSE

To assess the difference in the sonographic appearance of hip effusions when the hip was placed in the extended and abducted position as compared to a neutral position.

MATERIAL AND METHODS

Twenty-one consecutive children (aged 2-14 years) with hip pain or limping were examined for hip effusions by means of ultrasound. The capsule-femoral-neck distance, the presence of joint fluid, and the shape of the anterior capsule were compared in hips in slight extension and abduction with those in hips in a neutral position.

RESULTS

Of the 11 positive hip effusions, the maximal distance between the capsule and femoral neck was significantly larger (p < 0.005) in the extended and abducted hip position than in the neutral hip position, with a mean difference of 1.6 mm. Convex bulging of the anterior capsule was more confidently diagnosed in 3 hip effusions in the extended and abducted hip, and better visualization of fluid between the capsule and femoral neck was achieved in 4 joint in this posture.

CONCLUSION

The study demonstrated an improvement in the sonographic detection of hip effusion in the extended and abducted position compared to the neutral position.

Change of foot size with weightbearing. A study of 2829 children 3 to 18 years of age

The change of foot length and width with age has been reported in a few anthropometric studies in the literature. However, the relationship with body height rarely is reported, and the dynamic effect of weightbearing on foot size has not been documented. In this series, 2829 children 3 to 18 years of age of equal gender distribution were included in the study. The foot length and width on weightbearing and nonweightbearing were measured with a special precision electronic caliper. The foot length and width were found to increase linearly from the age of 3 years until 12 years in girls and 15 years in boys. This was followed by a phase during which the increase plateaued. The foot length and width increased significantly on weightbearing at all ages in both genders with a mean of 2.1 to 4.4 mm or 3.1% to 4.8%, respectively. The foot length and width also were found to correlate significantly with the body height in both genders, with a correlation coefficient of 0.96 to 0.98. No significant differences were found between the sizes of the dominant and nondominant foot in either gender.

Osteopenia in adolescent idiopathic scoliosis. A primary problem or secondary to the spinal deformity?

STUDY DESIGN

A cross-sectional study to assess the lumbar spinal and proximal femoral bone mineral density in girls aged 12, 13, or 14 years with adolescent idiopathic scoliosis and to compare them with bone mineral densities of an age-matched control group.

OBJECTIVES

To determine whether there is an association of osteopenia with idiopathic scoliosis, to compare bone mineral density in patients with scoliosis in different age groups with healthy controls, and to correlate bone mineral density with scoliotic parameters, including the pattern and magnitude of the curve.

SUMMARY OF BACKGROUND DATA

Routine radiographs allow very limited assessment of osteopenia. Therefore, only a few studies have compared osteopenia in patients with scoliosis with that in healthy individuals. New techniques allow a more reliable quantification of the bone mineral state in adolescent idiopathic scoliosis. Available series in the literature either had a small sample population with inadequate controls or examined a large age range.

METHODS

Using a dual energy x-ray absorptiometer, bone mineral density was measured in the predominant trabecular bone area, i.e., the lumbar spine (L2-L4) and bilateral proximal femur, in 81 girls aged 12, 13, or 14 years old with idiopathic scoliosis of various degrees of severity. Results were compared with those of 220 age-matched healthy control girls.

RESULTS

In all three age groups, scoliotic patients had significantly lower bone mineral density in all measured regions than that in the control individuals (student's t test). Sixty-eight percent of the scoliotic individuals had a significantly reduced bone mineral density. Differences in bone mineral density between bilateral hips (paired t test) were not statistically significant either in scoliotic patients or in healthy control individuals. No differences in body weight, body height, or menarche status were found between the scoliotic and control individuals. Correlation studies showed that, in scoliotic patients, the values of bone mineral density did not correlate with the curve degree or curve pattern.

CONCLUSIONS

There is a persistently lower bone mineral density in patients between 12 years and 14 years of age with idiopathic scoliosis. The decreased bone mineral density occurred in patients with idiopathic scoliosis before the age of 12 years, with no further progression from the age 12 to age 14, and did not correlate with the scoliosis degree or pattern. These findings suggest that the osteopenia in idiopathic scoliosis may be related to the primary etiology of the disease rather than secondary to the asymmetrical mechanical forces associated with the back deformities.

Cellular differentiation regulated by gibberellin in the Arabidopsis thaliana pickle mutant

The plant growth regulator gibberellin (GA) has a profound effect on shoot development and promotes developmental transitions such as flowering. Little is known about any analogous effect GA might have on root development. In a screen for mutants, Arabidopsis plants carrying a mutation designated pickle (pkl) were isolated in which the primary root meristem retained characteristics of embryonic tissue. Expression of this aberrant differentiation state was suppressed by GA. Root tissue from plants carrying the pkl mutation spontaneously regenerated new embryos and plants.

Dual-energy X-ray absorptiometry predicts bone formation in lower limb callotasis lengthening

The rate of regenerate bone mineral content (BMC) acceleration was studied using dual-energy X-ray absorptiometry (DEXA) in callotasis lengthening of the lower limb. Eleven youngsters (age range 5-17 years) undergoing callotasis lengthening for congenital, post-traumatic or post-infective conditions were studied longitudinally. Patients were initially scanned once a week until completion of the lengthening phase, and at 2-week intervals thereafter until removal of the fixator. They were subsequently followed up at regular intervals on an outpatient basis for up to 2 years after removal of the fixator (average, 14 months). The BMC accretion slopes exhibited by the patients and the rate of new bone formation allowed the identification of three groups. In the fast formation group, the rate of new bone formation was 0.3-0.6% per day. In the moderate formation group the rate of new bone formation is 0.1-0.3% per day, while in the poor formation group the rate of new bone formation is < 0.1% per day. From the analysis of time graphs, a direct correlation emerged between early bone formation and subsequent bone mineral content accretion. Measurement of BMC during callotasis lengthening in the lower limb allows precise monitoring of the process. It may prove useful to prevent complications occurring after removal of the fixator at an unduly early stage, such as plastic deformation and fracture through the regenerate bone. It may be used to predict the bone formation rate in a given patient, and to implement measures to try to influence it.

Auditory ERPs during rhyme and semantic processing: effects of reading ability in college students

Event-related potential (ERP), reaction time (RT), and response accuracy measures were obtained during the phonological and semantic categorization of spoken words in 14 undergraduates: 7 were average readers and 7 were reading-impaired. For the impaired readers, motor responses were significantly slower and less accurate than were those of the average readers in both classification tasks. ERPs obtained during rhyme processing displayed a relatively larger amplitude negativity at about 480 ms for the impaired readers as compared to the average readers, whereas semantic processing resulted in no major group differences in the ERPs at this latency. Also, N480 amplitude was larger during semantic relative to phonological classification for the average readers but not for the impaired readers. Results are compared to a previous study of reading-impaired children on the same tasks.

Subtalar realignment in congenital clubfoot using the Cincinnati approach

GOAL OF SURGERY

Surgical correction of clubfoot through an extensive and meticulous posterior, lateral, medial, subtalar, and plantar release.

INDICATIONS

Failed conservative treatment of clubfoot at 6 months of age.

CONTRAINDICATIONS

Previous failed surgery with a different incision.

PREOPERATIVE WORK UP

Radiographs of both foot and ankle in the anterior-posterior and lateral projections.

POSITIONING AND ANAESTHESIA

Supine. Tourniquet. General anaesthesia. Free draping above the knee.

SURGICAL TECHNIQUE

Through a Cincinnati incision the Achilles tendon is exposed and lengthened and the posterior capsule excised. The talofibular and the calcaneofibular ligaments are incised and released. The plantar aponeurosis is divided and the small plantar muscles are detached. Finally a medial release is achieved having excised the abductor hallucis muscles. Release of the dorsal talonavicular joint capsule. In severe cases the calcaneoucuboid joint must also be released. The corrected position is maintained with Kirschner wires.

POSTOPERATIVE MANAGEMENT

Long leg cast with the knee bent at 90 degrees . Cast changed after 10 to 14 days. Eight weeks postoperatively removal of cast and Kirschner wires and prescription of a Dennis-Brown boot to be worn for 12 to 18 months.

POSSIBLE COMPLICATIONS

Injury to neurovascular structures. Pin tract infection. Tightness, loosening or slipping of cast. Inadequate correction and damage to articular surfaces.

RESULTS

From 1985 to 1992 60 infants (70 feet) were operated. Average follow-up was 5 years (1 to 7). Assessment of clinical and functional results was based on the Magone rating system: 60% excellent, 18.6% good, 11% fair results were obtained; 2 infants had a minor skin breakdown, 7 were undercorrected and 2 were overcorrected.

Bone mineral acquisition in low calcium intake children following the withdrawal of calcium supplement

Our recent 18-month calcium supplementation trial demonstrated a significant increase in radial bone mineral mass in 7-year-old children with calcium intake approximately 300 mg/day (Am J Clin Nutr 1994; 60: 744-50). The persistence of higher bone mass after cessation of calcium supplementation is unknown. This is a follow-up study to investigate the lasting effect of calcium supplementation on bone acquisition. Subjects were 159 Chinese children aged 8.7 years. Distal one-third radial bone mineral content (BMC) and bone width (BW) were measured by single-photon absorptiometry. After 12 months, the significant difference in mean +/- SD percentage radial BMC disappeared between the study and control groups (7.34 +/- 6.77% vs 8.67 +/- 6.46%, p > 0.05). Dietary calcium intakes were similar between the groups. During the supplementation phase, the study group had 17.9% greater BMC gain than that of controls. In the follow-up phase, however, the study group had 16.1% less BMC gain than that of controls. It appears that an increased acquisition rate during the supplementation phase was almost balanced by a reduced acquisition rate during follow-up phase. Moreover, throughout the entire 30-month period, the overall BMC acquisition rates of the study and control groups were 25% and 23.8%, respectively. Hence, the overall acquisition rate of the study group was only 5% higher than that of controls. Therefore, the effect of calcium supplementation on bone mineral gain appears to reflect a transient reduction in bone turnover rate. Longer-term calcium trials are necessary to confirm whether a sustainable higher calcium intake throughout childhood will enhance peak bone mass.

Giant cell tumor of bone. Prognosis and treatment of pulmonary metastases

Giant cell tumor of bone is a challenging clinicopathologic entity. Despite its benign designation, it has the capacity to recur locally and develop rare pulmonary metastases. Between 1945 and 1991, 104 patients with histologically benign giant cell tumors of bone, 5 of which metastasized to the lung, were treated at the authors' institution. In these cases, histologic materials from the lung were identical to those found in the primary bone lesion. The primary bone lesions were treated with local curettage (3), wide resection (1), and wide resection with prosthesis placement (1). The patients were observed for a mean of 12.6 years (range, 5-38 years). Four of the 5 patients experienced local recurrences (average time interval, 34 months), with 3 patients experiencing 2 or more recurrences. The average time to lung metastasis was 23 months; 1 patient presented initially with pulmonary findings. Four patients underwent surgical resection of pulmonary metastases. All 4 patients are alive with no disease progression, despite incomplete pulmonary resections in 2 patients. Locally aggressive disease and multiple recurrences appear to be risk factors for pulmonary metastases in benign giant cell tumor of bone. Pulmonary metastases occurred within the first few years after discovery of primary bone tumors. Radiographs and computed tomographs of the chest are recommended to rule out this complication in patients with local recurrences. Resection of pulmonary metastasis is recommended. Long term survival is not incompatible with persistent pulmonary lesions.

Pigmented villonodular synovitis of the shoulder after anterior capsulolabral reconstruction

Pigmented villonodular synovitis (PVNS) is a proliferative disorder of the synovium affecting joints, bursae, or tendon sheaths. PVNS is further classified into diffuse and localized forms and rarely affects the shoulder. We report a case of nodular synovitis of the shoulder after arthroscopic and open anterior capsulolabral reconstruction. The histopathology and treatment of a nodular form of PVNS of the shoulder is discussed.

Geschlossene Reposition und perkutane Drahtfixation kindlicher suprakondylärer Extensionsfrakturen vom Typ III

GOAL OF SURGERY

Closed reduction of acute type III (according to Gartland) supracondylar extension fractures of the distal humerus and unicondylar pin fixation.

INDICATIONS

Type III and unstable type II supracondylar fractures.

CONTRAINDICATIONS

Swelling of the elbow. Compartment syndrome.

PREOPERATIVE WORK UP

Radiographs of both elbows in the anterior-posterior and lateral projections.

POSITIONING AND ANAESTHESIA

Supine with arm on arm board. General anaesthesia.

SURGICAL TECHNIQUE

Closed reduction through manipulation under fluoroscopic control. Fixation with 2 Kirschner wires introduced percutaneously through the lateral condyle. Long arm cast for 4 to 5 weeks.

POSTOPERATIVE MANAGEMENT

Radiographs on the first postoperative day, 1 week later and at time of cast and pin removal 4 to 5 weeks postoperatively. At that time active mobilisation of the elbow is started. Follow-up for 1 to 2 years is recommended.

POSSIBLE COMPLICATIONS

Damage of ossific nucleus of physis. Damage to neurovascular structures. Wire migration. Pin tract infection.

RESULTS

Out of 82 children (mean age 6.5 years) 73 had a follow-up of more than 6 months. 80.8% had good or excellent results. 15.1% had a decrease of the carrying angle of more than 10 degrees (4.1% more than 20 degrees ). There were 2 pin tract infections and 1 iatrogenic transient ulnar palsy.

The cutometer and ultrasonography in the assessment of postburn hypertrophic scar--a preliminary study

Sixteen patients with various degrees of postburn hypertrophic scars were evaluated by ultrasonography and elastometry. An Aloka Echo Camera (SSD-500) with a 7.5 MHz probe and a Cutometer SEM 575 skin elastometer were used. Serial monthly examinations were performed using both pieces of equipment. In some patients, more than one scar was assessed. The assessments were correlated with clinical grading of the progress of the scars. It was noted that ultrasonography was very sensitive in the localization of scar tissues, distinguishing them from normal skin, assessment of thickness and also delineation of the extent of scar tissues. The subcutaneous part of the scar could be assessed. Cutometer SEM 575 is a new machine that applies a gentle suction to the skin to measure its viscoelasticity. It is sensitive, the inter-observer variation is low, and it could be used for the grading of a scar. These two assessment techniques compliment other methods of scar assessment and will prove useful when assessment of response to treatment is required.

Nonsteroidal anti-inflammatory drugs and aspirin: a comparison of the antiplatelet effects

Antiplatelet effects of common analgesics were assessed in vitro. The Streck Platelet Aggregation Test Kit (Omaha, NE) was used to measure percent platelet aggregation in response to sodium arachidonate, collagen, adenosine diphosphate, and ristocetin in patients on various analgesics. In comparison with the control group, the response to arachidonate and collagen of ibuprofen (86% vs. 33% and 55% vs. 23%), naproxen (86% vs. 43% and 55% vs. 29%), indomethacin (86% vs. 26% and 55% vs. 17%), and aspirin (86 vs. 21% and 55 vs. 23%) all demonstrated a significant yet comparable reduction in platelet aggregation (p < 0.01). Because of the comparable antiplatelet effects of aspirin and NSAIDs, the additional benefits of daily aspirin in those patients on chronic and consistent NSAID therapy must be reconsidered.

Knee arthroscopy in Chinese children and adolescents: an eight-year prospective study

In the period January 1985 to December 1992, 69 Chinese boys and 20 Chinese girls (average 14.6 years, age range 6 to 16 years) with a total of 92 involved knees underwent examination under anaesthesia and knee arthroscopy. Two thirds of the patients were engaged in sports activities. A haemarthrosis was present in 51 patients. In one patient, Staphylococcus aureus was shown, and in two children a serous-purulent aspirate grew Mycobacterium tuberculosis. The lateral meniscus was torn in four knees and the medial meniscus in six. An intact discoid lateral meniscus was found in five girls. Three partial anterior cruciate ligament (ACL) tears, three complete ACL tears and two posterior cruciate ligament tears were diagnosed. One child had an osteochondral defect of the lateral femoral condyle accompanying an ACL and a lateral meniscal tear. Nonspecific synovitis of unknown etiology was diagnosed in six patients who had presented subacutely with at least a 2-month history of a symptomatic monoarticular knee effusion with low grade local inflammation and no history of major trauma. The synovitis gradually resolved over a 6- to 10-month period after arthroscopy. Knee arthroscopy in children and adolescent patients is safe, gives a high diagnostic accuracy, and allows treatment of a variety of intraarticular conditions. This study also demonstrates that the range of intraarticular knee problems found in Chinese children and adolescents differs from that described in their Western counterparts.

Cloning and nucleotide sequencing of the protease gene of Vibrio vulnificus

The gene (vvp) encoding a thermolabile protease of Vibrio vulnificus was cloned and sequenced. The transcription start point was also determined by primer extension. The product of this gene is very likely the secretory neutral metalloprotease that has been purified and characterized previously.

Refinement of the modified-relative-dose-response test as a method for assessing vitamin A status in a field setting: experience with Indonesian children

The modified-relative-dose-response (MRDR) test, which has been used extensively throughout the world for assessing vitamin A status, has been simplified. The major methodologic change resulting from the current studies in Indonesia is the use of graded standard doses of 3,4-didehydroretinyl acetate (DRA) based on the age range of the population of interest. Instead of a dose of 0.35 mumol/kg body wt, standard doses of 5.3 mumol for children younger than 6 y, 7.0 mumol for children between 6 and 12 y of age, and 8.8 mumol for adults and children > 12 y of age are suggested for field use. The acceptable time between administering the oral dose and obtaining a blood sample was validated as being 4-7 h in a group of children (n = 84) by taking two blood samples per child between 3 and 7 h after dosing with DRA. Furthermore, DRA in vitamin E-containing corn oil, with or without the addition of 4.6 mmol all-rac-alpha-tocopheryl acetate/L, was found to be stable for > or = 18 mo at 2 degrees C and at -20 degrees C, but not at 22 degrees C or at 37 degrees C. When DRA was stored in amber glass vials, stability was affected more by temperature than by exposure to room light. In keeping with earlier studies in adults, the ratio of 3,4-didehydro-retinol to retino tends to be independent of body weight. Indeed, slower growing children (ie, those with lower weight-for-age) may have a somewhat better vitamin A status than their heavier counterparts.

Paediatric sports injuries in Hong Kong: a seven year survey

OBJECTIVE

To ascertain the epidemiological characteristics of sports injuries in children in Hong Kong.

METHODS

Retrospective review of all cases seen in the Sports Injury Clinic of the Prince of Wales Hospital, Shatin, Hong Kong, in the period May 1984 to December 1990. The variables studied were age at presentation, gender, side of the body injured, anatomical location of the injury, type and severity of injury, sport played, level (school, recreational, amateur and professional) and frequency of sports participation, length in years of sports practice, and initial management of the injury.

RESULTS

Of the 2293 patients seen, 238 were youngsters (54% boys) 16 years old or younger. Ball games accounted for the greatest number of injuries, with 37 children taking part in basketball, 28 in soccer, 12 in volleyball, and 31 children taking part in a variety of other ball games. Of the remaining children, the single largest group was practising track and field, with sprinting and middle distance running accounting for 42 injuries, and 28 children were injured while cycling. Most of the injuries (85%) were classified as non-serious, but 15% of children presented with a total of 21 fractures, two joint dislocations, five concussions, and seven torn knee ligaments.

CONCLUSIONS

Children sports participation in Hong Kong, although not at high level and not as widespread as in the West, accounts for significant morbidity. These injuries should be carefully monitored to ascertain whether they result in any detrimental long term effects.

The hypertrophic scar and microcirculation properties

Blood-flow measurements of microcirculation were used as a quantitative indicator for scar assessment and healing. A laser doppler flowmeter (LDF), giving an integrated instantaneous flux value through a measured volume of skin, was used for the measurements. It has been postulated that the degree of hypertrophy after thermal injury correlates with the degree of microvascular regeneration. This study looked quantitatively at microcirculation in normal and scarred skin of different clinical grading and investigated the comparative responses to changes in local temperature stimuli. An attempt is made to define microcirculation using the parameters of Vasodilation Index (Dli) and Vasomotion Intensity (% Vsm) as respective responses to a rise in local temperature of the skin from 36 degrees C to 44 degrees C. The improvements in both Dli and % Vsm with healing of scar relate to the degree of microvascular regeneration, which in turn correlates with the clinical assessment.

Mechanical properties of normal skin and hypertrophic scars

The non-linear viscoelastic properties of skin tissue were characterized by modulus of elasticity E, which represents stiffness, and percentage extension (strain, xi) at load intensities of 20, 40 and 100 gm. The latter property is a measure of the extensibility for both normal skin and hypertrophic scar. A quasi-static extensometer applies a standard rate of extension to the skin and its mechanical properties were obtained from 15 Chinese patients with burn injuries of superficial to full skin thickness burns. Clinical evaluation of hypertrophic scar is qualitative and depends on colour, thickness and hardness or firmness. Using mechanical properties assists in the characterization by providing a quantitative indicator. Higher scar grading is synonymous with increased stiffness and decreased extensibility. Correlation with clinical assessment was achieved with these in vivo viscoelastic properties.

A follow-up study on the effects of calcium-supplement withdrawal and puberty on bone acquisition of children

Recent calcium supplementation trials in children have confirmed a positive but moderate effect of calcium intake on bone mineral accretion. However, the lasting effect of a higher bone mineral mass after calcium-supplement withdrawal is not known. This is an 18-mo follow-up study conducted after an 18-mo controlled calcium supplementation trial to study the persistent effect of higher bone mineral mass in children. Radial bone mineral mass was determined by single-photon absorptiometry; lumbar spine and femoral neck bone mineral mass were evaluated by dual-energy X-ray absorptiometry in 84 healthy Hong Kong children at age 8.5 y and these evaluations were repeated at age 10 y. Pubertal status was determined by Tanner staging. At the end of the follow-up, the differences in percentage gains in lumbar spine bone mineral content (12.1 +/- 8.2% compared with 14.9 +/- 10.05%, P = 0.24) and lumbar spine area (8.6 +/- 5.1% compared with 9.4 +/- 5.5%, P = 0.47) between the study and control groups disappeared. Dietary calcium intakes during follow-up were similar for the two groups (555 and 640 mg/d, P = 0.23). In multiple-regression analyses, pubertal status was the strongest correlate of bone acquisition and linear growth in the study period. In conclusion, higher percentage gains in bone mineral mass in childhood by calcium supplementation for 18 mo were reversible. Our study showed that the benefits of calcium supplementation disappear after treatment is withdrawn. Longer-term calcium trials are necessary to determine whether peak bone mass can be modified through sustained supplementation so that appropriate calcium intakes can be determined.

Femoral lengthening after type IVB septic arthritis of the hip in children

Septic arthritis of the hip in the newborn baby can result in severe long-term sequelae in the form of dislocation of the hip, loss of movement, and growth disturbance with leg-length discrepancy. For more severe discrepancies often with concomitant hip dislocation, no good solutions are readily available. This series comprised four patients with Choi's type IVB septic hip sequelae. They all had associated multiple-joint sepsis and resultant major leg-length discrepancies ranging from 6.9 to 14 cm. All underwent distraction lengthening with simultaneous correction of angulation and other deformities of the femur, three with the Ilizarov and one with the Orthofix system. The age at operation ranged from 9 to 13 years, with an average follow-up of 3 years. The overall lengthening achieved ranged from 4.5, 6.8, 12, to 13 cm, with the lengthening index from 24 to 51 days/cm. All hips remained stable, and the loss of range of hip and knee motion was not significant. Other complications included one deep pin-tract infection and one fracture of the callus.

Expression of DC8 is associated with, but not dependent on embryogenesis

DC8 is a late embryogenesis-abundant (LEA) protein gene isolated from carrot (Daucus carota). Deletion analysis of the DC8 promoter was performed to determine the sequences required for ABA and seed-specific regulation of DC8 transcription. To investigate the mechanism of DC8 expression during seed development, chimeric gene constructs containing DC8 promoter fragments fused to a promoterless beta-glucuronidase gene (DC8:GUS) were introduced into carrot, tobacco (Nicotiana tobacum) and Arabidopsis thaliana plants. Seed-specific DC8 expression patterns was conserved among the three plant species. However, differences among the species in the patterns of DC8 expression in the embryo and endosperm that correlated with differences in the rates of embryo and endosperm growth were found. Lack of correspondence between DC8 activation and embryo development among the seeds of the three species suggests that DC8 expression, which is associated with seed maturation, is not coupled to the embryo development program. The presence of DC8 activity in carrot callus and endosperm is consistent with the notion that DC8 expression is independent of embryo morphogenesis. A similar DC8 activity time-course during callus induction and seed development suggests that explantation and 2,4-D treatment initiates a course of events similar to that in the carrot ovule. After fertilization, two pathways one leading to embryo development and another to seed maturation are initiated, but they are not closely linked. As a result we find DC8, part of the maturation program, being activated at different embryonic stages in different plant species.

Late cognitive brain potentials, phonological and semantic classification of spoken words, and reading ability in children

Event-related potential (ERP), reaction time, and response accuracy measures were obtained during rhyming and semantic classification of spoken words in 10 average (mean age 11.64 years) and 9 impaired reading (mean age 12.10 years) children. The behavioral measures of classification did not distinguish the groups. In the ERPs, rhyme processing produced more pronounced group differences than did semantic processing at about 480 ms, with a relatively more negative distribution for the impaired readers at centroparietal sites. At about 800 ms in both classification tasks, the impaired readers displayed a late positivity that was delayed in latency and of larger amplitude at frontal sites than that for the average readers. The ERP findings suggest that the categorization of spoken words for meaning and sound result in increasingly more aberrant correlates of these processing demands in reading-impaired children.