Effects of thermal boundary condition on methane oxidation in landfill cover soil at different ambient temperatures

Microbial aerobic methane oxidation (MAMO) has been considered as an environmental-friendly method for mitigating methane emission from municipal landfill sites. Soil column has in a landfill cover under one-dimensional (1-D) condition. However, most of the published soil column tests failed to simulate 1-D heat transfer due to the use of thermal conductive boundary at the sidewall. In the present study, a heavily instrumented soil column was developed to quantify the effects of thermal boundary condition on the methane oxidation efficiency under different ambient temperatures in landfill cover soil. The sidewall of the soil column was thermally insulated to ensure 1-D heat transport as would have been typically expected in the field condition. Two soil column tests with and without thermal insulation were conducted at a range of controlled ambient temperatures from 15 to 30°C, for studying how soil moisture, matric suction, gas pressure, soil temperature and gas concentration evolve with MAMO. The test results reveal that ignoring thermal insulation in a soil column test would result in a greater loss of soil heat generation by MAMO and hence oxidation efficiency by up to 100% for the range of temperature considered. When the ambient temperature increased to 30°C (but less than the optimum temperature for MAMO), the MAMO efficiency increased abruptly at first but then decreased substantially with time, and this is likely due to the accumulation of biomass generated by MAMO.

Theoretical analysis of coupled effects of microbe and root architecture on methane oxidation in vegetated landfill covers

Reduction of soil moisture by plant root-water uptake could improve soil aeration for microbial aerobic methane oxidation (MAMO) in a landfill cover, but excessive soil moisture removal could suppress microbial activity due to water shortage. Existing models ignore the coupled microbe-vegetation interaction. It is thus not known whether the presence of plants is beneficial or adverse to MAMO. This study proposes a newly-improved theoretical model that couples the effects of root-water uptake and microbial activity for capturing water-gas flow and MAMO in unsaturated soils. Parametric studies are conducted to investigate the effects of root characteristics and transpiration rate on MAMO efficiency. Uniform, parabolic, exponential and triangular root architectures are considered. Ignoring the effects of water shortage on microbe over-predicts the MAMO efficiency significantly, especially for plants with traits that give high root-water uptake ability (i.e., uniformly-rooted and long root length). The effects of plants on MAMO efficiency depends on the initial soil moisture strongly. If the soil is too dry (i.e., close to the permanent wilting point), plant-water uptake, with any root architecture considered, would reduce MAMO efficiency as further soil water removal by plants suppresses microbial activity. Plants with exponential or triangular root architectures could preserve 10% higher MAMO than the other two cases. These two architectures are more capable of minimizing the adverse effects of root-water uptake due to microbial water shortage. This implies that high-water-demand plants such as those with long root length and with uniform or parabolic root architectures require more frequent irrigation to prevent from excessive reduction of MAMO efficiency.

Numerical modelling of methane oxidation efficiency and coupled water-gas-heat reactive transfer in a sloping landfill cover

Microbial aerobic methane oxidation in unsaturated landfill cover involves coupled water, gas and heat reactive transfer. The coupled process is complex and its influence on methane oxidation efficiency is not clear, especially in steep covers where spatial variations of water, gas and heat are significant. In this study, two-dimensional finite element numerical simulations were carried out to evaluate the performance of unsaturated sloping cover. The numerical model was calibrated using a set of flume model test data, and was then subsequently used for parametric study. A new method that considers transient changes of methane concentration during the estimation of the methane oxidation efficiency was proposed and compared against existing methods. It was found that a steeper cover had a lower oxidation efficiency due to enhanced downslope water flow, during which desaturation of soil promoted gas transport and hence landfill gas emission. This effect was magnified as the cover angle and landfill gas generation rate at the bottom of the cover increased. Assuming the steady-state methane concentration in a cover would result in a non-conservative overestimation of oxidation efficiency, especially when a steep cover was subjected to rainfall infiltration. By considering the transient methane concentration, the newly-modified method can give a more accurate oxidation efficiency.

A multicenter phase II study of sorafenib, capecitabine, and oxaliplatin (SECOX) in patients with advanced hepatocellular carcinoma: Final results of Hong Kong-Singapore Hepatocellular Carcinoma Research Collaborative Group study

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Background: This is a single arm, multi-center, phase II study to assess the efficacy and tolerability of sorafenib, oxaliplatin and capecitabine combination for the treatment of advanced hepatocellular carcinoma (HCC) patients. Methods: Eligible patients received SECOX regime—sorafenib 400 mg bid (Day one-fourteen), oxaliplatin 85 mg/m2 (Day one) and capecitabine 1700 mg/m2(Day one-seven) every two weeks. Response assessment was based on RECIST 1.0 criteria. The primary endpoint was time-to-progression (TTP) and the secondary endpoints were tumor response rate (RR), progression-free survival (PFS), overall survival (OS) and tolerability. Results: A total of 51 patients were enrolled in the trial.The median age was 58 years (range, 28-81) and 84% of patients were chronic hepatitis B carriers. Ninety percent of recruited patients belonged to BCLC stage C disease and 41 (80%) patients had extra-hepatic metastasis. The best RR was 16% and they were all partial response. Another 62% of patients achieved stable disease for at least eight weeks. The median TTP was 5.29 months (95% CI 3.81-5.88 months), PFS 5.26 months (95% CI 3.75-5.88 months) and OS was 11.73 months (95% CI 8.87- 15.38 months). Diarrhea (75%), Hand-foot-skin reaction (73%) and transient liver function derangement were the most commonly encountered adverse events, with the majority of patients having grade one or two. No treatment-related death was reported. Conclusions: The SECOX regime indicates preliminary promising activity and safety in Asian population with advanced HCC. Our data support a randomized trial comparing SECOX versus sorafenib alone for treatment of advanced HCC. Clinical trial information: NCT00752063.

Drooling in children

Although drooling may occur in healthy children under two years of age, it is commonly observed in neurologically impaired children and carries a considerable social stigma. Drooling can be socially embarrassing, and at times may cause serious medical complications. Drooling may result from the hypersecretion of saliva or, more commonly, the impairment of swallowing. Most of the causes of drooling can be diagnosed from a history and physical examination of the patient. Laboratory investigations are usually unnecessary. Treatment should be directed at the underlying cause whenever possible. No active management is necessary for patients who have little functional and psychological impairment from their objectively mild or intermittent drooling. Treatment options for moderate and severe drooling include physiotherapy, behavioural or biofeedback modification, pharmacotherapy and surgery.

Acute appendicitis in an incarcerated inguinal hernia

A preterm infant with acute appendicitis in an incarcerated inguinal hernia is described. We suggest that extraluminal compression of the neck of a hernial sac caused by incarceration may be a predisposing factor for appendicitis.

State-of-the-art methods for geometric and biomechanical assessments of residual limbs: a review

A review is presented on the state-of-the-art methods for geometric and biomechanical assessments of residual limb tissues. Residual limb assessments are needed throughout different stages of prosthetic management, namely preamputation, residual limb maturation, prosthetic design, prosthetic fitting, and subsequent follow-ups. Geometric assessments include the monitoring of the volumetric change as the residual limb matures after amputation. Geometric and biomechanical assessments of the residual limb are important considerations in prosthetic design. Quantitative geometric and biomechanical assessments are becoming more important in the development of a computer-aided system for prosthetic socket design. It is noted that, except for the external shape measurements of residual limbs, most of the instruments used in residual limb assessment are not particularly cost-effective for clinical applications in prosthetics. Further developments are needed to facilitate the incorporation of the internal geometric assessments and biomechanical assessments into the current computer-aided design systems for clinical prosthetics.

Scarring resulting from chickenpox

Nine hundred and eighty-six children (519 boys, 467 girls) who had chickenpox at least 1 year previously were examined for the presence of scars resulting from this disease. Ninety-six (18.5%) boys and 88 (18.8%) girls had chickenpox scars, giving rise to an overall prevalence of 18.7%. The scars were found on the face in 75 (40.8%), neck 2 (1.1%), shoulders 8 (4.3%), upper limbs 15 (8.2%), anterior thorax 50 (27.2%), abdomen 106 (57.6%), back 65 (35.3%), buttocks 9 (4.9%), and lower limbs 12 (6.5%) affected children. The mean number of scars in the 184 children was 2.8 (standard deviation 1.9). The scars were hyperpigmented in 32, hypopigmented in 160, depressed in 38, and hypertrophic in 32 children. Keloids were noted in two children.

Evaluating the child with purpura

Purpura is the result of hemorrhage into the skin or mucosal membrane. It may represent a relatively benign condition or herald the presence of a serious underlying disorder. Purpura may be secondary to thrombocytopenia, platelet dysfunction, coagulation factor deficiency or vascular defect. Investigation to confirm a diagnosis or to seek reassurance is important. Frequently, the diagnosis can be established on the basis of a careful history and physical examination, and a few key laboratory tests. Indicated tests include a complete blood cell count with platelet count, a peripheral blood smear, and prothrombin and activated partial thromboplastin times.

Structural analyses of nucleotide binding to an aminoglycoside phosphotransferase

3',5"-Aminoglycoside phosphotransferase type IIIa [APH(3')-IIIa] is a bacterial enzyme that confers resistance to a range of aminoglycoside antibiotics while exhibiting striking homology to eukaryotic protein kinases (ePK). The structures of APH(3')-IIIa in its apoenzyme form and in complex with the nonhydrolyzable ATP analogue AMPPNP were determined to 3.2 and 2.4 A resolution, respectively. Furthermore, refinement of the previously determined ADP complex was completed. The structure of the apoenzyme revealed alternate positioning of a flexible loop (analogous to the P-loop of ePK's), occupying part of the nucleotide-binding pocket of the enzyme. Despite structural similarity to protein kinases, there was no evidence of domain movement associated with nucleotide binding. This rigidity is due to the presence of more extensive interlobe interactions in the APH(3')-IIIa structure than in the ePK's. Differences between the ADP and AMPPNP complexes are confined to the area of the nucleotide-binding pocket. The position of conserved active site residues and magnesium ions remains unchanged, but there are differences in metal coordination between the two nucleotide complexes. Comparison of the di/triphosphate binding site of APH(3')-IIIa with that of ePK's suggests that the reaction mechanism of APH(3")-IIIa and related aminoglycoside kinases will closely resemble that of eukaryotic protein kinases. However, the orientation of the adenine ring in the binding pocket differs between APH(3')-IIIa and the ePK's by a rotation of approximately 40 degrees. This alternate binding mode is likely a conserved feature among aminoglycoside kinases and could be exploited for the structure-based drug design of compounds to combat antibiotic resistance.

Functions of the Growth Arrest Specific 1 Gene in the Development of the Mouse Embryo

The growth arrest specific 1 (gas1) gene is highly expressed in quiescent mammalian cells (Schneider et al., 1988, Cell 54, 787-793). Overexpression of gas1 in normal and some cancer cell lines could inhibit G(0)/G(1) transition. Presently, we have examined the functions of this gene in the developing mouse embryo. The spatial-temporal expression patterns for gas1 were established in 8.5- to 14.5-day-old embryos by immunohistochemical staining and in situ hybridization. Gas1 was found heterogeneously expressed in most organ systems including the brain, heart, kidney, limb, lung, and gonad. The antiproliferative effects of gas1 on 10.5 and 12.5 day limb cells were investigated by flow cytometry. In 10.5 day limbs cells, gas1 overexpression could not prevent G(0)/G(1) progression. It was determined that gas1 could only induce growth arrest if p53 was also coexpressed. In contrast, gas1 overexpression alone was able to induce growth arrest in 12.5 day limb cells. We also examined the cell cycle profile of gas1-expressing and nonexpressing cells by immunochemistry and flow cytometry. For 10.5 day Gas1-expressing heart and limb cells, we did not find these cells preferentially distributed at G0/G1, as compared with Gas1-negative cells. However, in the 12.5 day heart and limb, we did find significantly more Gas1-expressing cells distributed at G0/G1 phase than Gas1-negative cells. These results implied that Gas1 alone, during the early stages of development, could not inhibit cell growth. This inhibition was only established when the embryo grew older. We have overexpressed gas1 in subconfluent embryonic limb cells to determine the ability of gas1 to cross-talk with various response elements of important transduction pathways. Specifically, we have examined the interaction of gas1 with Ap-1, NFkappaB, and c-myc responsive elements tagged with a SEAP reporter. In 10.5 day limb cells, gas1 overexpression had little effect on Ap-1, NFkappaB, and c-myc activities. In contrast, gas1 overexpression in 12.5 day limb cells enhanced AP-1 response while it inhibited NFkappaB and c-myc activities. These responses were directly associated with the ability of gas1 to induce growth arrest in embryonic limb cells. In the 12.5 day hindlimb, gas1 was found strongly expressed in the interdigital tissues. We overexpressed gas1 in these tissues and discovered that it promoted interdigital cell death. Our in situ hybridization studies of limb sections and micromass cultures revealed that, during the early stages of chondrogenesis, only cells surrounding the chondrogenic condensations expressed gas1. The gene was only expressed by chondrocytes after the cartilage started to differentiate. To understand the function of gas1 in chondrogenesis, we overexpressed the gene in limb micromass cultures. It was found that cells overexpressing gas1/GFP could not participate in cartilage formation, unlike cells that just express the GFP reporter. We speculated that the reason gas1 was expressed outside the chondrogenic nodules was to restrict cells from being recruited into the nodules and thereby defining the boundary between chondrogenic and nonchondrogenic forming regions.

Crystal structure of the lytic transglycosylase from bacteriophage lambda in complex with hexa-N-acetylchitohexaose

The three-dimensional structure of the lytic transglycosylase from bacteriophage lambda, also known as bacteriophage lambda lysozyme, complexed to the hexasaccharide inhibitor, hexa-N-acetylchitohexaose, has been determined by X-ray crystallography at 2.6 A resolution. The unit cell contains two molecules of the lytic transglycosylase with two hexasaccharides bound. Each enzyme molecule is found to interact with four N-acetylglucosamine units from one hexasaccharide (subsites A-D) and two N-acetylglucosamine units from the second hexasaccharide (subsites E and F), resulting in all six subsites of the active site of this enzyme being filled. This crystallographic structure, therefore, represents the first example of a lysozyme in which all subsites are occupied, and detailed protein-oligosaccharide interactions are now available for this bacteriophage lytic transglycosylase. Examination of the active site furthermore reveals that of the two residues that have been implicated in the reaction mechanism of most other c-type lysozymes (Glu35 and Asp52 in hen egg white lysozyme), only a homologous Glu residue is present. The lambda lytic transglycosylase is therefore functionally closely related to the Escherichia coli Slt70 and Slt35 lytic transglycosylases and goose egg white lysozyme which also lack the catalytic aspartic acid.

Mongolian spots with involvement of the temporal area

A Chinese baby girl was born after an uncomplicated pregnancy and a normal spontaneous vaginal delivery to a gravida 2, para 1, 32-year-old mother at 37 weeks' gestation. Neither parent had a history of alcohol or drug ingestion. There was no history of consanguinity. The Apgar scores were 7 at 1 min and 9 at 5 min. Her birth weight was 5 lb 14 oz and her length was 46 cm. At birth, she was noted to have grayish areas on the face and lower back. The infant was seen at 3 months of age because of persistent regurgitations. On average, she regurgitated 7-8 times a day. Physical examination showed that the infant was not in distress. Her weight was 6 lb 4 oz and length 47 cm. She had a Mongolian spot measuring 0.8 x 1.2 cm in the left temporal area (Fig. 1) and another Mongolian spot measuring 4 cm in diameter in the lumbar area. The Mongolian spots were grayish in color and the pigmentation was uniform in intensity. The rest of the examination was essentially normal. The infant was diagnosed to have Mongolian spots and gastroesophageal reflux. The latter was treated with postural therapy, thickened feedings, and metoclopramide 0.35 mg q.i.d. The infant was seen again at 4 months of age for a reassessment. There was no noticeable change in shape, size, or color of the Mongolian spots.

Iron deficiency anemia

Iron deficiency anemia is the most common cause of anemia worldwide and results from inadequate iron supply for erythropoiesis. Iron deficiency is most prevalent during periods of rapid body growth: in infancy and again at puberty. Insufficient intake accounts for most cases. The clinical manifestations of iron deficiency anemia can be subtle, but irreversible delayed psychomotor development may occur if the anemia is severe and prolonged. The optimal approach is prevention and early treatment.

Crystallization of the Mycobacterium tuberculosis cell-division protein FtsZ

Mycobacterium tuberculosis FtsZ (MtbFtsZ), an essential protein in bacterial cell division, has been crystallized in the presence of a new inhibitor of MtbFtsZ polymerization and GTPase activity, ethyl (6-amino-2,3-dihydro-4-phenyl-1H-pyrido[4,3-b][1, 4]diazepin-8-yl)carbamate (SRI-7614). Crystals of the MtbFtsZ-SRI-7614 complex (form I, 30% polyethylene glycol 4000, 0.1 M sodium citrate pH 5.6, 0.2 M NH(4)OAc, 293 K) belong to space group P6(1) or P6(5), with unit-cell parameters a = 88.78, c = 178. 02 A, and diffract to 2.3 A resolution. A second crystal form, of the GDP complex, grows in the presence or absence of Mg(2+) from PEG 4000 at 277 K or from (NH(4))(2)SO(4) at 293 K, respectively (form II, space group P6(2)22 or P6(4)22, with unit-cell parameters a = 135.02, c = 328.97 A or a = 129.30, c = 327.97 A, respectively). Complete data sets to approximately 7 A resolution have been collected from both. Exceptional form II crystals diffract to at least 4.5 A resolution. Determination of the MtbFtsZ structure may advance the design of improved inhibitors of FtsZ polymerization.

Oedema in childhood

Oedema is a common childhood problem with important public health implications. It is an abnormal accumulation of fluid in the interstitial space which might result from a decrease in intravascular oncotic pressure, an increase in intravascular hydrostatic pressure, an increase in capillary permeability or impaired lymphatic drainage. Renal sodium retention is an important factor in generalised oedema. This article reviews the pathophysiology and aetiology of oedema in children and suggests an approach to evaluation, diagnosis and management of the problem.

Garlic burns

A 3-month-old infant with blistering lesions and a second-degree burn from topical application of garlic is reported. The literature on garlic burns is reviewed.

Scleral melanocytosis and oculodermal melanocytosis (nevus of Ota) in Chinese children

Two thousand nine hundred fourteen Chinese children (1510 males and 1404 females) were examined for the presence of scleral melanocytosis (SM) and oculodermal melanocytosis in a cross-sectional prevalence survey. SM was found in 4.9% of boys and 4.1% of girls under the age of 1 year. The peak prevalence was at 6 years of age, when 44.6% of boys and 46.6% of girls were affected. At 18 years of age, only 11.1% of boys and 13.2% of girls had SM. The overall prevalence, regardless of age, was 27.6% in boys and 27. 1% in girls. The condition was bilateral in 78% of cases. The medial superior quadrant was the most frequently affected site, and the lateral inferior quadrant was the least frequently affected site. Oculodermal melanocytosis occurred only in one patient; the pigmentation affected the left side of the face and the ipsilateral sclera.

Secondary nocturnal enuresis

Secondary nocturnal enuresis accounts for about one quarter of patients with bed-wetting. Although a psychological cause is responsible in some children, various other causes are possible and should be considered. This article reviews the epidemiology, psychological and social impact, causes, investigation, management, and prognosis of secondary nocturnal enuresis.

Subcutaneous nodules in Henoch-Schönlein purpura

A 6.5-year-old boy with active Henoch-Schönlein purpura developed subcutaneous nodules (SCN), a vasculitic manifestation previously unreported in children with this disease. The authors suggest that pressure played a role in the pathogenesis of the SCN.

Otalgia in children

Otalgia is a common symptom in the pediatric age group. The most common cause is acute otitis media, followed by otitis externa. In the majority of cases, the diagnosis can be established by a thorough history and a careful otologic examination. When the otologic findings are normal and the etiology is obscure, a thorough work-up to determine the source of referred pain is essential. Laboratory investigations are usually not necessary. Treatment should always be directed at the underlying cause.

Evaluating the child with proteinuria

Proteinuria is a common laboratory finding in children. It might represent a benign condition or herald the presence of a serious underlying renal disease or systemic disorder. Investigation to confirm a diagnosis or seek reassurance is important. This paper discusses the various causes of proteinuria, and those aspects of the history, physical examination, and the laboratory tests that will help determine the cause or reassure that a serious problem is not currently present.

Bmp-4 requires the presence of the digits to initiate programmed cell death in limb interdigital tissues

The effects of Bmp-4 on interdigital cell death were investigated in the mouse. Affi-Gel beads, loaded with recombinant Bmp-4 protein, were transplanted into the interdigital tissues of day 12.5 hindlimb, ex utero. It was established that Bmp-4 could induce precocious interdigital cell death. Using in situ hybridization, the expression patterns of bmp-4 and alk-6 receptor were established. Both genes were found coexpressed in the interdigital region of 12.5- and 13. 5-day hindlimbs. This suggests that Bmp-4 may act in an autocrine fashion. We have also studied the effects of Bmp-4 on 12.5-day interdigital tissue cultures. In all specimens examined, the interdigital tissues produced cartilage instead of participating in cell death. The addition of exogenous Bmp-4 to the interdigital cultures did not induce apoptosis but instead enhanced chondrogenesis. The discrepancy between the effects of Bmp-4 in vitro and ex utero was attributed to the presence of digits. When a flanking digit was left attached to the interdigital tissues, in vitro, Bmp-4 promoted apoptosis instead of chondrogenesis. In sum, the results suggest that Bmp-4 is a multifunctional protein and its effect on the interdigital tissues is dependent on the modulating influence of the digits.

Diagnosis of stridor in children

Stridor is a sign of upper airway obstruction. In children, laryngomalacia is the most common cause of chronic stridor, while croup is the most common cause of acute stridor. Generally, an inspiratory stridor suggests airway obstruction above the glottis while an expiratory stridor is indicative of obstruction in the lower trachea. A biphasic stridor suggests a glottic or subglottic lesion. Laryngeal lesions often result in voice changes. A child with extrinsic airway obstruction usually hyperextends the neck. The airway should be established immediately in children with severe respiratory distress. Treatment of stridor should be directed at the underlying cause.

Application of image analysis techniques to two-dimensional crossed immunoelectrophoresis study

Two-dimensional crossed immunoelectrophoresis (2D-CIEP) is a technique widely used for studying composition of protein mixtures in biological and clinical studies. A low cost image analysis system with the use of an optical flatbed scanner and a IBM-compatible PC was set up in this work for capturing 2D-CIEP patterns. A computer package CIEPEASY was developed for modification and analysis of the image acquired to determine various peak parameters such as the migration distance, peak height and peak area of the constituting components for both qualitative and quantitative studies. In this approach, more composition information of the standard and sample gel patterns could be extracted from the proposed image analysis system. The time required for data collection and interpretation of 2D-CIEP images was shortened significantly and the results obtained have a higher accuracy than those obtained by using conventional methods. Moreover, a linear relationship between the peak area and the amount of antigen present in a sample was confirmed accurately and reported for the first time in the literature.

Extensive mongolian spots with involvement of the scalp

A Chinese infant boy had extensive Mongolian spots in the occipital, gluteal, sacrococcygeal, and lumbar areas. The occurrence of a Mongolian spot in the scalp area has not been previously reported. Awareness of such an occurrence is important so that a false accusation of child abuse is not made.

Nocturnal leg cramps in children: incidence and clinical characteristics

The records of 2527 healthy children seen in an ambulatory care clinic were evaluated for nocturnal leg cramps in the preceding 12 months, frequency and duration of the cramps, whether the cramps affected one leg or both legs at a time, whether there was associated muscle cramps in feet, whether the cramps occurred when the child was awake or asleep, and whether there was residual tenderness in the affected muscles. Nocturnal leg cramps were present in 185 children for an overall incidence of 7.3%. Leg cramps were noted only in children aged > or = 8 years. The incidence increased at 12 years and peaked at 16 to 18 years of age. A majority (81.6%) of the affected children had nocturnal leg cramps 1 to 4 times per year. The mean duration of episodes was 1.7 minutes. Leg cramps were unilateral in 98.9% of cases and the ipsilateral foot also was involved in 18.9% of cases. One hundred thirty-five (73%) children had leg cramps while asleep, and the remaining 23 (12.4%) children had leg cramps in either state. Fifty-seven (30.8%) children had residual tenderness in the affected muscles. The mean duration of residual tenderness was 33.2 minutes (range: 2 minutes-1 day). We conclude that nocturnal leg cramps are common in children aged > 12 years. A majority of the affected children have leg cramps 1 to 4 times per year. The cramps are usually unilateral and occur when the children are asleep. Normal duration of the leg cramp is < 2 minutes. Residual tenderness is present in approximately 30% of the affected children. Residual tenderness, if present, usually lasts for half an hour.

Evaluation and management of the child with speech delay

A delay in speech development may be a symptom of many disorders, including mental retardation, hearing loss, an expressive language disorder, psychosocial deprivation, autism, elective mutism, receptive aphasia and cerebral palsy. Speech delay may be secondary to maturation delay or bilingualism. Being familiar with the factors to look for when taking the history and performing the physical examination allows physicians to make a prompt diagnosis. Timely detection and early intervention may mitigate the emotional, social and cognitive deficits of this disability and improve the outcome.

Hypohidrosis in children

Hypohidrosis has many causes. The condition may be generalised or segmental, acute or progressive and central or peripheral in origin. Most of the causes can be diagnosed from the history and physical examination. Laboratory investigations are usually not necessary. Treatment should be directed at the underlying cause whenever possible.

Multiple sialoliths and a sialolith of unusual size in the submandibular duct: a case report

A 49-year-old man with multiple sialoliths in the submandibular duct is described. One of the sialoliths was of remarkable size. This report is of interest because of the unusual size and weight of this sialolith and because of the patient's symptoms, which were relatively mild and of short duration.

Hepatocyte growth factor stimulates chemotactic response in mouse embryonic limb myogenic cells in vitro

In this study we investigate the influence of Hepatocyte Growth Factor (HGF) on the motility of embryonic forelimb myoblasts. Using Blindwell chemotactic chambers, it was found that HGF at concentrations of 1-50 ng/ml dramatically enhanced the ability of myogenic cells to migrate. This stimulatory effect was elicited in a dose-dependent fashion and the effect was reversed with the addition of HGF neutralizing antibodies. A checkerboard analysis was performed and it revealed that HGF's effect on limb myoblast motility was through both chemokinesis and chemotaxis. HGF was also examined for its ability to stimulate myogenic cell proliferation, using MF20 antibody as the myogenic marker. At all concentrations tested, HGF did not stimulate an overall increase in the numbers of MF20-positive myoblasts in culture. To examine the chemokinetic effect of HGF on cell migration in the limb, cells were isolated from the proximal regions of the limb (areas rich in myogenic cells), exposed to HGF, labeled with DiI and transplanted into 11.5 day mouse forelimbs. After 36 h of culture, it was found that DiI-labeled limb cells, pretreated with HGF, migrated significantly further in the limb than labeled cells that have not been exposed to HGF. The chemotactic effect of HGF was also investigated by implanting beads loaded with and without HGF into the 11.5 day limb. Proximal to the beads, DiI-labeled limb cells were also transplanted. It was found that HGF was able to chemotactically attract and direct the migration of DiI-labeled limb cells. Immunohistological staining was performed with HGF antibodies to determine the distribution of HGF in the 11.5 day mouse forelimb. It was found that HGF was strongly expressed by the apical ectodermal ridge (AER), the ectoderm and the mesenchyme directly beneath the AER. Positive staining was also obtained for the myogenic regions. However, the pattern was heterogeneous--punctuated with myogenic cells expressing and not expressing HGF.

Pruritus in children

Pruritus is the most common of all dermatological complaints. Although pruritus is usually due to a primary skin disease, it may be a manifestation of a systemic illness. The majority of causes can be diagnosed from the history and physical examination. Laboratory investigations are usually not necessary. Treatment should be directed at the underlying cause whenever possible.

Mechanism of N-acetylgalactosamine binding to a C-type animal lectin carbohydrate-recognition domain

The mammalian hepatic asialoglycoprotein receptor, a member of the C-type animal lectin family, displays preferential binding to N-acetylgalactosamine compared with galactose. The structural basis for selective binding to N-acetylgalactosamine has been investigated. Regions of the carbohydrate-recognition domain of the receptor believed to be important in preferential binding to N-acetylgalactosamine have been inserted into the homologous carbohydrate-recognition domain of a mannose-binding protein mutant that was previously altered to bind galactose. Introduction of a single histidine residue corresponding to residue 256 of the hepatic asialoglycoprotein receptor was found to cause a 14-fold increase in the relative affinity for N-acetylgalactosamine compared with galactose. The relative ability of various acyl derivatives of galactosamine to compete for binding to this modified carbohydrate-recognition domain suggest that it is a good model for the natural N-acetylgalactosamine binding site of the asialoglycoprotein receptor. Crystallographic analysis of this mutant carbohydrate-recognition domain in complex with N-acetylgalactosamine reveals a direct interaction between the inserted histidine residue and the methyl group of the N-acetyl substituent of the sugar. Evidence for the role of the side chain at position 208 of the receptor in positioning this key histidine residue was obtained from structural analysis and mutagenesis experiments. The corresponding serine residue in the modified carbohydrate-recognition domain of mannose-binding protein forms a hydrogen bond to the imidazole side chain. When this serine residue is changed to valine, loss in selectivity for N-acetylgalactosamine is observed. The structure of this mutant reveals that the beta-branched valine side chain interacts directly with the histidine side chain, resulting in an altered imidazole ring orientation.

Can we predict body height from segmental bone length measurements? A study of 3,647 children

It is well known that significant differences exist in the anthropometric data of different races and ethnic groups. This is a cross-sectional study on segmental bone length based on 3,647 Chinese children of equal sex distribution aged 3-18 years. The measurements included standing height, weight, arm span, foot length, and segmental bone length of the humerus, radius, ulna, and tibia. A normality growth chart of all the measured parameters was constructed. Statistical analysis of the results showed a very high linear correlation of height with arm span, foot length, and segmental bone lengths with a correlation coefficient of 0.96-0.99 for both sexes. No differences were found between the right and left side of all the segmental bone lengths. These Chinese children were found to have a proportional limb segmental length relative to the trunk.

Biomedical gait evaluation of the immediate effect of orthotic treatment for flexible flat foot

Flexible flat foot subjects attending the prosthetics and orthotics units come with prescriptions from orthopaedic surgeons for arch supports. Usually a pair of thermoformed plastic inserts are fabricated and fitted to treat the patients. However the effect of the orthotic treatment is not yet clear. A motion analysis system with two video cameras placed on the lateral and rear sides of the subject together with one force platform was used to investigate the immediate effects of the orthotic treatment. The force platform collected force data and the two cameras captured two-dimensional displacement data of the lower limb. Eight subjects, all having an arch index (AI) larger than 3.0 participated in the study. For each subject, three successful steps on the force platform were videotaped for both the shod (with shoe only) and the orthotic (with shoe and orthosis) conditions. The kinetic variables were normalized to individual body weight and averaged for each subject. A Paired t-test was conducted to analyse sample means of matched pairs between the shod and the orthotic conditions. The results showed changes in displacement data with relatively little change in the collected force data. The modified UCBL shoe insert evaluated significantly affected the orientation and movements of the subtalar joint, ankle joint and knee joint. These immediate effects reduced the degree and duration of abnormal pronation during the stance phase and thus had the potential for decreasing strain in the plantar ligaments and reducing abnormal tibial rotation which may be therapeutic for the foot.