One hundred years of orthopedics in the Netherlands. VIII. Pediatric orthopedics

Orthopaedic disorders in children differ in type from those in adults: most frequent are congenital anomalies and disorders of growth and development. The special nature and relative rarity of these conditions justify the separate development of this branch of the discipline. Fractures almost always heal normally after closed reduction and immobilization in a plaster cast; fractures close to epiphyseal discs and in joints require special attention. Slipping of the upper femoral epiphysis necessitates surgical fixation of the epiphysis. Benign bone tumours occur relatively often and mostly require no surgical intervention. The prognosis of solid malignant bone tumours has improved since the introduction of (neo)adjuvant chemotherapy and limb-sparing surgery. In case of difference in leg length, the length of both legs is predicted with the aid of roentgenological measurements. Inhibition of the growth of the longer leg gives rise to fewer complications than lengthening of the short leg. The essence of the treatment of growth disorders due to abnormal ossification of the cartilage is to monitor the natural repair process and to intervene if permanent malformation threatens.     

Identification of myoglobin in human smooth muscle

Myoglobin (Mb) has been believed to be absent generally from mammalian smooth muscle tissue. Examination of human rectal, uterine, bladder, colon, small intestine, arterial, and venous smooth muscle by immunohistochemical techniques shows that each of these tissues is immunopositive for both smooth muscle myosin and human Mb. Mb-specific primers were used for the polymerase chain reaction to generate cDNA from smooth muscle tissues. Southern hybridization with a Mb-specific probe gave a very strong signal with the cDNA from rectum, weaker signals from small intestine and uterus, a faint signal from colon, and no signal from bladder tissue. High performance liquid chromatography analysis coupled with sequence determination has shown that contaminating heme-binding serum albumin as well as hemoglobin in extracts of smooth muscle seriously compromise any heme-based or spectrophotometric assay of Mb. Combined affinity and size exclusion chromatography, however, provide the necessary resolution. The cDNA-derived amino acid sequence of human smooth muscle Mb was found to be identical to that of Mb from striated muscle.     

Toxoplasmosis in goats in the Netherlands: a pilot study

A pilot-study was carried out on ten Dutch goat farms to see whether there is a relationship between farm management factors and the occurrence of toxoplasmosis. Questionnaires were used to collect information about farm management factors and blood samples were taken to determine the prevalence of toxoplasmosis on these farms. The mean prevalence was 47% (range 5-90%). The presence of kittens on a farm was a risk factor for a higher prevalence of toxoplasmosis.     

Diaphragm activation with intramuscular stimulation in dogs

We studied in 10 supine anesthetized dogs diaphragm contraction produced by electrical activation with intramuscular electrodes surgically implanted in the ventral surface of the diaphragm and compared this with activation of the ipsilateral phrenic nerve (C5, 6, and 7) before it entered the thorax. Repetitive 40-Hz pulse trains with supramaximal current stimulus were used after hyperventilation of the animals to apnea. A single intramuscular electrode within 1 to 2 cm of the site of phrenic nerve entry into the diaphragm produced a mean transdiaphragmatic pressure of 12.0 cm H2O +/- 0.97 SE and mean tidal volume of 0.27 L +/- 0.04 SE. Mean values observed with phrenic nerve stimulation were not statistically different, and both electrode systems produced equivalent outward abdominal motion and upper rib cage paradox, as monitored by inductive plethysmography. There was no difference in gas exchange during stimulation with a single hemidiaphragm electrode and mechanical ventilation compared at the same tidal volume and respiratory rate. Blockade of neuromuscular transmission with curare eliminated intramuscular and phrenic nerve stimulation proportionately, suggesting that activation of the diaphragm is dependent in both cases on the phrenic nerve. This technique does not entail manipulation of the phrenic nerve and may have clinical application as an alternative technique for diaphragm pacing.     

A technique for identifying the subgroup membership of certain misarticulating children

Cluster analysis was used to identify two homogeneous clusters of 8-9 1/2-year-old children who misarticulated /s/, /r/, or both. The analysis was based on the children's scores on 40 measures of language, reading, auditory processing, and other variables. Discriminant function analysis was then used to identify a subset of five measures and a means of computing classification scores. These measures and the classification scores can be used to identify the cluster membership of new subjects. The use of classification scores for identifying cluster membership was cross-validated against cluster analysis of a second group of children. The two clusters are described in terms of their performance on language and reading measures.     

Multiple biological sequence alignment in heterogeneous multicore clusters with user-selectable task allocation policies

Multiple Sequence Alignment (MSA) is an important problem in Bioinformatics that aims to align more than two sequences in order to emphasize similarity regions. This problem is known to be NP-Hard, so heuristic methods are used to solve it. DIALIGN-TX is an iterative heuristic method for MSA that generates alignments by concatenating ungapped regions with high similarity. Usually, the first phase of MSA algorithms is parallelized by distributing several independent tasks among the nodes. Even though heterogeneous multicore clusters are becoming very common nowadays, very few task allocation policies were proposed for this type of architecture. This paper proposes an MPI/OpenMP master/slave parallel strategy to run DIALIGN-TX in heterogeneous multicore clusters, with several allocation policies. We show that an appropriate choice of the master node has great impact on the overall system performance. Also, the results obtained in a heterogeneous multicore cluster composed of 4 nodes (30 cores), with real sequence sets show that the execution time can be drastically reduced when the appropriate allocation policy is used.     

The sizes of peptides generated from protein by mammalian 26 and 20 S proteasomes. Implications for understanding the degradative mechanism and antigen presentation

Knowledge about the sizes of peptides generated by proteasomes during protein degradation is essential to fully understand their degradative mechanisms and the subsequent steps in protein turnover and generation of major histocompatibility complex class I antigenic peptides. We demonstrate here that 26 S and activated 20 S proteasomes from rabbit muscle degrade denatured, nonubiquitinated proteins in a highly processive fashion but generate different patterns of peptides (despite their containing identical proteolytic sites). With both enzymes, products range in length from 3 to 22 residues, and their abundance decreases with increasing length according to a log-normal distribution. Less than 15% of the products are the length of class I presented peptides (8 or 9 residues), and two-thirds are too short to function in antigen presentation. Surprisingly, these mammalian proteasomes, which contain two "chymotryptic," two "tryptic," and two "post-acidic" active sites, generate peptides with a similar size distribution as do archaeal 20 S proteasomes, which have 14 identical sites. Furthermore, inactivation of the "tryptic" sites altered the peptides produced without significantly affecting their size distribution. Therefore, this distribution is not determined by the number, specificity, or arrangement of the active sites (as proposed by the "molecular ruler" model); instead, we propose that proteolysis continues until products are small enough to diffuse out of the proteasomes.