Children with repaired bilateral cleft lip/palate: effect of age at premaxillary osteotomy on facial growth.

This study compared facial growth in three groups of patients with bilateral complete cleft lip/palate: those who had (1) no premaxillary osteotomy, (2) premaxillary osteotomy before age 8 years, and (3) premaxillary osteotomy after age 8 years. Of 24 children with bilateral complete cleft lip/palate, 7 had early premaxillary osteotomy (mean age, 6.1; range, 3.7 to 7.6 years), 10 had late osteotomy (mean age, 11.2; range, 8.3 to 20.7 years), and 7 did not require premaxillary repositioning and served as controls (mean age, 12.4; range, 6.4 to 17.8 years). Presurgical and postsurgical lateral cephalograms were digitized using the Dentofacial Planner software; most current lateral cephalograms comprised the control group. Forty-one bony and 25 soft-tissue landmarks were digitized, and 8 angles were measured: SNA, (sella-nasion-A point), SNPg (sella-nasion-pogonion), ANB (A point-nasion-B point), NAPg (nasion-A point-pogonion), ST convexity (glabella-subnasale-soft-tissue pogonion), Sn-G vertical (line perpendicular to the horizontal plane dropped from glabella and distance measured from subnasale to this vertical), Cm-Sn-Ls (columella-subnasale-abial superioris), and Sn-Gn-C (subnasale-soft-tissue gnathion-chin point). Statistical difference in mean preoperative and postoperative values were measured with analysis of variance. Tests of significance were adjusted for multiple comparisons using the Bonferroni correction. Mean age at follow-up for early, late, and control groups was 11.8, 14.0, and 12.4 years, respectively. Mean follow-up for early and late groups was 5.7 and 2.8 years. There was a significant preoperative difference among the three groups for mean SNA (p < 0.01), ANB (p < 0.01), and NAPg (p < 0.01). Bonferroni analyses revealed that the early group had significantly greater SNA, ANB, and NAPg angles than the late (p < 0.01) and control groups (p < 0.05). There was a significant postoperative difference among groups for ANB (p < 0.05); Bonferroni analyses also showed that the control group had a significantly greater ANB than the late group (p < 0.05). The t test for equity of means established postoperative change for SNA (p < 0.01), ANB (p< 0.01), NAPg (p < 0.01), and ST convexity (p < 0.01) for the early group was significantly greater than for the late group. Children who required early premaxillary positioning had more significant preoperative deformity; however, this group's postoperative profile was not, on average, significantly different from either the late or control groups. Our findings that the early group had more significant change with premaxillary osteotomy than the late group suggest that premaxillary positioning can be done before completion of facial growth without compromise.     

Stent implantation through a self-expanding stent

Jailing of a side-branch is a known complication of stent implantation, and makes access to the side-branch difficult, especially if the stent is of the self-expanding type. Although plain balloon angioplasty is feasible for the jailed side-branches, the use of newer devices (a stent, Rotablation or atherectomy) has not been described. We describe a novel way of treating a side-branch jailed by a self-expanding stent by using stent implantation through the strut of a self-expanding stent.     

Hierarchical analysis of variation in the mitochondrial 16S rRNA gene among Hymenoptera

Nucleotide sequences from a 434-bp region of the 16S rRNA gene were analyzed for 65 taxa of Hymenoptera (ants, bees, wasps, parasitoid wasps, sawflies) to examine the patterns of variation within the gene fragment and the taxonomic levels for which it shows maximum utility in phylogeny estimation. A hierarchical approach was adopted in the study through comparison of levels of sequence variation among taxa at different taxonomic levels. As previously reported for many holometabolous insects, the 16S data reported here for Hymenoptera are highly AT-rich and exhibit strong site-to-site variation in substitution rate. More precise estimates of the shape parameter (alpha) of the gamma distribution and the proportion of invariant sites were obtained in this study by employing a reference phylogeny and utilizing maximum-likelihood estimation. The effectiveness of this approach to recovering expected phylogenies of selected hymenopteran taxa has been tested against the use of maximum parsimony. This study finds that the 16S gene is most informative for phylogenetic analysis at two different levels: among closely related species or populations, and among tribes, subfamilies, and families. Maximization of the phylogenetic signal extracted from the 16S gene at higher taxonomic levels may require consideration of the base composition bias and the site-to-site rate variation in a maximum-likelihood framework.      

A high-throughput microscale method to release N-linked oligosaccharides from glycoproteins for matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis

This report describes a convenient method for the rapid and efficient release of N-linked oligosaccharides from low microgram amounts of glycoproteins. A 96-well MultiScreen assay system containing a polyvinylidene difluoride (PVDF) membrane is employed to immobilize glycoproteins for subsequent enzymatic deglycosylation. Recombinant tissue-type plasminogen activator (rt-PA) is used to demonstrate the deglycosylation of 0.1-50 micrograms of a glycoprotein. This method enabled the recovery of a sufficient amount of N-linked oligosaccharides released enzymatically with peptide N-glycosidase F (PNGaseF) from as little as 0.5 microgram rt-PA for subsequent analysis by matrix-assisted laser desorption/ionization time-of-flight (MALDI- TOF) mass spectrometry. The immobilization of rt-PA to the PVDF membrane did not sterically inhibit the PNGaseF-mediated release of oligosaccharides from rt-PA as determined by tryptic mapping experiments. Comparison of the oligosaccharides released from 50 micrograms of rt-PA by either the 96-well plate method or by a standard solution digestion procedure showed no significant differences in the profiles obtained by high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Both neutral and sialylated oligosaccharide standards spiked into wells were recovered equally as determined by HPAEC-PAD. One advantage of this approach is that reduction and alkylation can be performed on submicrogram amounts of glycoproteins with easy removal of reagents prior to PNGaseF digestion. In addition, this method allows 60 glycoprotein samples to be deglycosylated in 1 day with MALDI-TOF or HPAEC-PAD analysis being performed on the following day.      

Progression of facial asymmetry in hemifacial microsomia

Hemifacial microsomia is a common craniofacial anomaly, variably affecting structures derived from the first and second pharyngeal arches. Correction of the skeletal deformity in children has been advocated to improve growth potential and reduce secondary deformity. However, contrary reports have suggested that facial asymmetry in hemifacial microsomia does not increase with growth; therefore, skeletal correction can be postponed, even until adolescence. The purpose of this study was to test the hypothesis that facial asymmetry in hemifacial microsomia is progressive. This is a retrospective evaluation of 67 patients with untreated hemifacial microsomia. The patients were categorized as: group I (mandible type I, IIa), n = 38, and group II (mandible type IIb, III), n = 29. Pretreatment posterior-anterior cephalometric radiographs were used to analyze asymmetry by measuring the angle between the true horizontal and the following planes: piriform rim, maxillary occlusal plane, and intergonial angle. Angular measurements were averaged for patients in the deciduous (<6 years), mixed (> or =6<13 years), and permanent dentition (> or =13 years). In group I, angle piriform rim, maxillary occlusal plane, and intergonial angle increased from 7.0, 4.3, and 4.4 to 8.4, 6.6, and 6.1 degrees, respectively [mean age, 4.1 (deciduous) to 8.6 (mixed) to 21.0 (permanent) years]. In group II, angle piriform rim, maxillary occlusal plane, and intergonial angle increased from 9.5, 6.2, and 5.3 to 11.7, 7.6, and 8.0 degrees, respectively [mean age, 3.4 (deciduous) to 8.0 (mixed) years]. These data demonstrate that hemifacial microsomia is progressive and underscores the importance of early surgical correction of mandibular asymmetry in this disorder.     

Analysis of fronto-orbital advancement for Apert, Crouzon, Pfeiffer, and Saethre-Chotzen syndromes

The purposes of this study were (1) to document outcome after primary fronto-orbital advancement for the four major eponymous craniosynostotic syndromes (Apert, Crouzon, Pfeiffer, and Saethre-Chotzen) and (2) to identify factors that might influence need for primary and secondary fronto-orbital advancement or foreheadplasty. Also tested was the hypothesis that coincident sagittal synostosis could modulate brachycephaly and affect whether a primary or secondary frontal operation was necessary. Data were collected on age and indications for initial operation, type of primary and secondary frontal procedures, and concomitant sagittal synostosis. Patients initially managed by subcranial Le Fort III were included in the study group but excluded from analysis of fronto-orbital advancement. Patients treated by monobloc advancement or Le Fort III osteotomies with frontal grafting or Anderl modification were assessed as having had primary fronto-orbital advancement. Minimum time to follow-up was 5 years. A total of 126 patients met inclusion criteria. Lateral photographs were examined to assess preoperative and postoperative sagittal position of supraorbital rims-to-globes. Frontal re-advancement was indicated if the corneal apex was anterior to the supraorbital rim. Foreheadplasty was indicated for unacceptable frontal contour and normal supraorbital rim-to-globe relationship. Primary correction for frontal retrusion was not required in 4 percent of Apert (1 of 25), 16 percent of Crouzon (7 of 44), 6 percent of Pfeiffer (2 of 31), and 19 percent of Saethre-Chotzen (5 of 26) patients. Of those infants who had a primary fronto-orbital advancement, reoperation for either supraorbital retrusion or frontal deformity was necessary in all 16 Apert patients and in 5 of 19 Crouzon (26 percent), 10 of 26 Pfeiffer (38 percent), and 13 of 20 Saethre-Chotzen (65 percent) patients (p < 0.001). Age at initial fronto-orbital advancement did not influence reoperative rate. No correlation was found between concomitant sagittal synostosis and necessity for primary or secondary frontal correction (p = 0.22). In summary, phenotypic diagnosis was determinant for outcome as defined by need for secondary fronto-orbital advancement, foreheadplasty, or both. Apert patients had the highest incidence of reoperation for frontal retrusion or forehead contour. Crouzon and Saethre-Chotzen patients were most likely to express a minor phenotype and not require fronto-orbital correction. Coincident sagittal synostosis did not influence frontal projection, as reflected in need for either primary or secondary frontal advancement.     

Autosomal dominant craniometaphyseal dysplasia is caused by mutations in the transmembrane protein ANK

Craniometaphyseal dysplasia (CMD) is a rare skeletal disorder characterized by progressive thickening and increased mineral density of craniofacial bones and abnormally developed metaphyses in long bones. Linkage studies mapped the locus for the autosomal dominant form of CMD to an approximately 5-cM interval on chromosome 5p, which is defined by recombinations between loci D5S810 and D5S1954. Mutational analysis of positional candidate genes was performed, and we describe herein three different mutations, in five different families and in isolated cases, in ANK, a multipass transmembrane protein involved in the transport of intracellular pyrophosphate into extracellular matrix. The mutations are two in-frame deletions and one in-frame insertion caused by a splicing defect. All mutations cluster within seven amino acids in one of the six possible cytosolic domains of ANK. These results suggest that the mutated protein has a dominant negative effect on the function of ANK, since reduced levels of pyrophosphate in bone matrix are known to increase mineralization.     

Nucleotide sequence of the Acinetobacter calcoaceticus trpGDC gene cluster

A plasmid library of Acinetobacter calcoaceticus HindIII fragments was constructed, and clones that complemented an Escherichia coli pabA mutant were selected. Plasmids containing a 3.9-kb fragment of A. calcoaceticus DNA that also complemented E. coli trpD and trpC-(trpF+) mutants were obtained. We infer that complementation of E. coli pabA mutants was the result of the expression of the amphibolic anthranilate- synthase/p-aminobenzoate-synthase glutamine-amidotransferase gene and that the plasmid insert carried the entire trpGDC gene cluster. In E. coli minicells, the plasmid insert directed the synthesis of polypeptides of 44,000, 33,000, and 20,000 daltons, molecular masses that are consistent with the reported molecular masses of phosphoribosylanthranilate transferase, indoleglycerol-phosphate synthase, and anthranilate-synthase component II, respectively. A 3,105- bp nucleotide sequence was determined. Comparison of the A. calcoaceticus trpGDC sequences with other known trp gene sequences has allowed insight into (1) the evolution of the amphibolic trpG gene, (2) varied strategies for coordinate expression of trp genes, and (3) mechanisms of gene fusions in the trp operon.      

Two modes of gating during late Na+ channel currents in frog sartorius muscle

Na+ currents were measured during 0.4-s depolarizing pulses using the cell-attached variation of the patch-clamp technique. Patches on Cs-dialyzed segments of sartorius muscle of Rana pipiens contained an estimated 25-500 Na+ channels. Three distinct types of current were observed after the pulse onset: a large initial surge of inward current that decayed within 10 ms (early currents), a steady "drizzle" of isolated, brief, inward unitary currents (background currents), and occasional "cloudbursts" of tens to hundreds of sequential unitary inward currents (bursts). Average late currents (background plus bursts) were 0.12% of peak early current amplitude at -20 mV. 85% of the late currents were carried by bursting channels. The unit current amplitude was the same for all three types of current, with a conductance of 10.5 pS and a reversal potential of +74 mV. The magnitudes of the three current components were correlated from patch to patch, and all were eliminated by slow inactivation. We conclude that all three components were due to Na+ channel activity. The mean open time of the background currents was approximately 0.25 ms, and the channels averaged 1.2 openings for each event. Neither the open time nor the number of openings of background currents was strongly sensitive to membrane potential. We estimated that background openings occurred at a rate of 0.25 Hz for each channel. Bursts occurred once each 2,000 pulses for each channel (assuming identical channels). The open time during bursts increased with depolarization to 1-2 ms at -20 mV, whereas the closed time decreased to less than 20 ms. The fractional open time during bursts was fitted with m infinity 3 using standard Na+ channel models. We conclude that background currents are caused by a return of normal Na+ channels from inactivation, while bursts are instances where the channel's inactivation gate spontaneously loses its function for prolonged periods.     

Kinetics of veratridine action on Na channels of skeletal muscle

Veratridine bath-applied to frog muscle makes inactivation of INa incomplete during a depolarizing voltage-clamp pulse and leads to a persistent veratridine-induced Na tail current. During repetitive depolarizations, the size of successive tail currents grows to a plateau and then gradually decreases. When pulsing is stopped, the tail current declines to zero with a time constant of approximately 3 s. Higher rates of stimulation result in a faster build-up of the tail current and a larger maximum value. I propose that veratridine binds only to open channels and, when bound, prevents normal fast inactivation and rapid shutting of the channel on return to rest. Veratridine-modified channels are also subject to a "slow" inactivation during long depolarizations or extended pulse trains. At rest, veratridine unbinds with a time constant of approximately 3 s. Three tests confirm these hypotheses: (a) the time course of the development of veratridine-induced tail currents parallels a running time integral of gNa during the pulse; (b) inactivating prepulses reduce the ability to evoke tails, and the voltage dependence of this reduction parallels the voltage dependence of h infinity; (c) chloramine-T, N-bromoacetamide, and scorpion toxin, agents that decrease inactivation in Na channels, each greatly enhance the tail currents and alter the time course of the appearance of the tails as predicted by the hypothesis. Veratridine-modified channels shut during hyperpolarizations from -90 mV and reopen on repolarization to -90 mV, a process that resembles normal activation gating. Veratridine appears to bind more rapidly during larger depolarizations.