Inhibition by long-chain acyl-CoAs of glucose 6-phosphate metabolism in plastids isolated from developing embryos of oilseed rape (Brassica napus L.)

The effects of long-chain acyl-CoA (lcACoA) esters (both added exogenously and synthesized de novo) and acyl-CoA binding protein (ACBP) on plastidial glucose 6-phosphate (Glc6P) and pyruvate metabolism were examined using isolated plastids. The binding of lcACoA esters by ACBP stimulated the utilization of Glc6P for fatty acid synthesis, starch synthesis and reductant supply via the oxidative pentose phosphate (OPP) pathway. Stimulation occurred at low (1-10 microM) concentrations of ACBP. Pyruvate-dependent fatty acid synthesis was not directly affected by ACBP. However, addition of ACBP did increase the Glc6P-dependent stimulation of pyruvate utilization mediated through the OPP pathway. On the basis of these experiments, we conclude that lcACoA esters may inhibit Glc6P uptake into plastids, and that this inhibition is relieved by ACBP. We also suggest that utilization of other substrates for fatty acid synthesis may be affected by lcACoA/ACBP via their effects on the OPP pathway.

Structure and binding specificity of the second N-terminal cellulose-binding domain from Cellulomonas fimi endoglucanase C

The 1,4-beta-glucanase CenC from Cellulomonas fimi contains two cellulose-binding domains, CBD(N1) and CBD(N2), arranged in tandem at its N-terminus. These homologous CBDs are distinct in their selectivity for binding amorphous and not crystalline cellulose. Multidimensional heteronuclear nuclear magnetic resonance (NMR) spectroscopy was used to determine the tertiary structure of CBD(N2) in the presence of saturating amounts of cellopentaose. A total of 1996 experimental restraints were used to calculate an ensemble of 21 final structures for the protein. CBD(Nu2) is composed of 11 beta-strands, folded into two antiparallel beta-sheets, with a topology of a jellyroll beta-sandwich. On the basis of patterns of chemical shift perturbations accompanying the addition of cellooligosaccharides, as well as the observation of intermolecular protein-sugar NOE interactions, the cellulose-binding site of CBD(N2) was identified as a cleft that lies across one face of the beta-sandwich. The thermodynamic basis for the binding of cellooligosaccharides was investigated using isothermal titration calorimetry and NMR spectroscopy. Binding is enthalpically driven and consistent with a structural model involving hydrogen bonding between the equatorial hydroxyls of the glucopyranosyl rings and polar amino acid side chains lining the CBD(N2) cleft. Affinity electrophoresis was used to determine that CBD(N2) also binds soluble beta-1,4-linked polymers of glucose, including hydroxyethylcellulose and beta-1,3-1,4-glucans. This study complements a previous analysis of CBD(N1) [Johnson, P. E., Joshi, M. D., Tomme, P., Kilburn, D. G., and McIntosh, L. P. (1996) Biochemistry 35, 14381-14394] and demonstrates that the homologous CBDs from CenC share very similar structures and sugar binding properties.

The NMR structure of the nucleocapsid protein from the mouse mammary tumor virus reveals unusual folding of the C-terminal zinc knuckle

The nucleocapsid protein (NC) from the mouse mammary tumor virus (MMTV) has been overexpressed in Escherichia coli and purified to homogeneity for structural studies by nuclear magnetic resonance (NMR) spectroscopy. The protein contains two copies of a conserved zinc-coordinating "CCHC array" or "zinc knuckle" motif common to the nucleocapsid proteins of nearly all known retroviruses. The residues comprising and adjacent to the zinc knuckles were assigned by standard two-dimensional (1)H and three-dimensional (1)H-(15)N NMR methods; the rotational dynamic properties of the protein were determined from (15)N relaxation experiments, and distance restraints derived from the nuclear Overhauser effect (NOE) data were used to calculate the three-dimensional structure. The (1)H-(1)H NOE and (15)N relaxation data indicate that the two zinc knuckles do not interact with each other, but instead behave as independently folded domains connected by a flexible 13-residue linker segment. The proximal zinc knuckle folds in a manner that is essentially identical to that observed previously for the two zinc knuckles of the human immunodeficiency virus type 1 nucleocapsid protein and for the moloney murine leukemia virus nucleocapsid zinc knuckle domain. However, the distal zinc knuckle of MMTV NC exhibits a rare three-dimensional fold that includes an additional C-terminal beta-hairpin. A similar C-terminal reverse turn-like structure was observed recently in the distal zinc knuckle of the Mason-Pfizer monkey virus nucleocapsid protein [Gao, Y., et al. (1998) Protein Sci. 7, 2265-2280]. However, despite a high degree of sequence homology, the conformation and orientation of the beta-hairpin in MMTV NC is significantly different from that of the reverse turn in MPMV NC. The results support the conclusion that structural features of NC zinc knuckle domains can vary significantly among the different genera of retroviridae, and are discussed in terms of the recent and surprising discovery that MMTV NC can facilitate packaging of the HIV-1 genome in chimeric MMTV mutants.

In situ splitting of a rib graft for reconstruction of the orbital floor

A technique of in situ split rib graft harvest is described. It has been used in bone graft reconstructions of the orbital floor when small, thin, malleable grafts are desired. The advantages of in situ rib harvest are technical simplicity, diminished risks of known rib harvest-associated complications, and avoidance of the risks involved with in situ split cranial bone harvesting.

Production of prostanoids and nitric oxide by infarcted heart in situ and the effect of aspirin

The production of prostacyclin (PGI2) and thromboxane A2 (TXA2) in infarcted and noninfarcted portions of the rabbit heart was studied prior to and following administration of acetylsalicylic acid (aspirin). Aspirin was administered intravenously (iv) as water-soluble Aspisol, d-lysinmono (acetylsalicylate) (Bayer, Leverkusen, Germany) into an ear vein. A branch of the left circumflex coronary artery was ligated. The animals were divided into three groups. The first group received 150 mg/kg/day of aspirin (75 mg/kg of aspirin every 12 h, n = 10). The first administration of aspirin was 1 h after ligation of the coronary artery and the last injection was 1 h before euthanasia. The second group received 5 mg/kg/day of aspirin (every 24 h, n = 10). A separate group of rabbits not receiving aspirin served as controls (n = 12). Two days following onset of ischemia, inducible form of nitric oxide synthase (iNOS) was measured in heart muscle and the oxidation products of nitric oxide (nitrite, NO-2 plus nitrate, NO-3: their sum referred to as NOx) were determined in arterial and coronary venous blood. Concentrations of both PGI2 and TXA2 were elevated in the infarcted portions of the heart compared to the noninfarcted regions. Formation of prostanoids was accompanied by increased activation of iNOS. Both doses of aspirin diminished the concentrations of PGI2 and TXA2 in infarcted heart muscle; in contrast, small doses of aspirin failed to influence myocardial iNOS activity. Apparently small doses of aspirin changed the relationship of iNOS to cyclooxygenase (COX). Coronary arterial-venous difference of NOx and myocardial iNOS activity showed parallel increases. Diminution of prostacyclin by aspirin can damage gastric mucosa and interfere with vasodilatation. Since NO counters these deficiencies, a combination of aspirin with a nitric oxide donor may be advantageous.

The cellulose-binding domains from Cellulomonas fimi beta-1, 4-glucanase CenC bind nitroxide spin-labeled cellooligosaccharides in multiple orientations

The N-terminal cellulose-binding domains CBDN1 and CBDN2 from Cellulomonas fimi cellulase CenC each adopt a jelly-roll beta-sandwich structure with a cleft into which amorphous cellulose and soluble cellooligosaccharides bind. To determine the orientation of the sugar chain within these binding clefts, the association of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl-4-yl) spin-labeled derivatives of cellotriose and cellotetraose with isolated CBDN1 and CBDN2 was studied using heteronuclear 1H-15N NMR spectroscopy. Quantitative binding measurements indicate that the TEMPO moiety does not significantly perturb the affinity of the cellooligo-saccharide derivatives for the CBDs. The paramagnetic enhancements of the amide 1HN longitudinal (DeltaR1) and transverse (DeltaR2) relaxation rates were measured by comparing the effects of TEMPO-cellotetraose in its nitroxide (oxidized) and hydroxylamine (reduced) forms on the two CBDs. The bound spin-label affects most significantly the relaxation rates of amides located at both ends of the sugar-binding cleft of each CBD. Similar results are observed with TEMPO-cellotriose bound to CBDN1. This demonstrates that the TEMPO-labeled cellooligosaccharides, and by inference strands of amorphous cellulose, can associate with CBDN1 and CBDN2 in either orientation across their beta-sheet binding clefts. The ratio of the association constants for binding in each of these two orientations is estimated to be within a factor of five to tenfold. This finding is consistent with the approximate symmetry of the hydrogen-bonding groups on both the cellooligosaccharides and the residues forming the binding clefts of the CenC CBDs.

Estrogen improves working but not reference memory and prevents amnestic effects of scopolamine of a radial-arm maze

This study investigated the effect of estrogen treatment on working memory and reference memory of female rats. In addition, the impact of estrogen on the sensitivity of these two types of memory to the cholinergic antagonist scopolamine was investigated. At 35 days of ages, rats were ovariectomized and implanted chronically with Silastic capsules containing either 25% crystalline estradiol or 100% cholesterol. Thirty days after surgery, animals were trained on an eight-arm radial maze with four arms baited to assess both working and reference memory performance. Following training, females were given scopolamine hydrobromide (0.2 mg/kg i.p.) prior to retesting on the task. Results indicated that estrogen treatment improved working memory performance during maze acquisition but did not affect reference memory performance. Scopolamine treatment impaired performance on the working memory component, but not the reference memory component, while estrogen prevented the impairment of working memory by scopolamine. Results support previous evidence that estrogen selectively enhances performance on tasks that depend on working memory.

Calcium binding by the N-terminal cellulose-binding domain from Cellulomonas fimi beta-1,4-glucanase CenC

The interaction of the N-terminal cellulose-binding domain, CBDN1, from Cellulomonas fimi beta-1,4-glucanase CenC with calcium was investigated using NMR spectroscopy and calorimetry. CBDN1 binds a single calcium ion with an equilibrium association constant of approximately 10(5) M-1 at 35 degreesC and pH 6.0. Binding is exothermic (-42 +/- 2 kJ mol-1) under these conditions and is accompanied by a small negative change in heat capacity (DeltaCp = -0.41 +/- 0.16 kJ mol-1 K-1). From an NMR line shape analysis, the rate constants for calcium association and dissociation were found to be (5 +/- 2) x 10(7) s-1 M-1 and (4.5 +/- 0.6) x 10(2) s-1, respectively. The rapid association kinetics indicate that the calcium-binding site on CBDN1 is accessible and, to the first approximation, preformed. Based on patterns of chemical shift perturbations, and structural comparisons with the Bacillus sp. 1, 3-1,4-beta-glucanases, the backbone carbonyl oxygens of Thr8, Gly30, and Asp142 and a side chain carboxyl oxygen of Asp142 are postulated to form the calcium-binding site of CBDN1. Consistent with the calcium-independent affinity of CBDN1 for cellopentaose, this exposed site is located on the face of CBDN1 opposite to that forming the oligosaccharide-binding cleft. The midpoint denaturation temperature of CBDN1 is increased by approximately 8 degreesC at pH 6.0 in the presence of saturating amounts of calcium, confirming that metal ion binding is thermodynamically linked to native-state stability.

New reference allelic ladders to improve allelic designation in a multiplex STR system

This paper reports the composition of a new reference allelic ladder mixture for use with a multiplex DNA profiling system consisting of six short tandem repeat loci. The loci included in this mixture are HUMTH01, D21S11, D18S51, D8S1179, HUMVWAF31/A, HUMFIBRA/FGA and an amelogenin sex test. Sequence analysis of individual ladder alleles was carried out and allelic designations made in accordance with the recommendations of the International Society of Forensic Haemogenetics (1992; 1994). A series of rare alleles which increase the range of alleles previously reported were identified. By including some of the rare alleles into the ladder marker system, we have significantly improved the ability to identify new alleles in unknown samples.

Radiologic percutaneous gastrostomy: results in 56 patients with head and neck cancer

OBJECTIVE

The establishment of a direct enteral feeding route is critical in the overall treatment of many patients with head and neck cancer. Use of radiologic percutaneous gastrostomy (RPG), the newest technique for gaining enteral access, has not been studied in such patients extensively. This study evaluated the indications, technique, success rate, and complications associated with RPG in patients with head and neck cancer.

STUDY DESIGN

Retrospective.

METHODS

A comprehensive chart review was undertaken of 56 patients with head and neck cancer treated at a tertiary care institution who had undergone successful or attempted RPG at some point during their treatment course.

RESULTS

Most study patients had advanced oropharyngeal squamous cell carcinoma. The most frequent indications for RPG were dysphagia/aspiration following tumor resection (n = 26) and dysphagia following completion of single- or combined-modality therapy (n = 22). The success rate of attempted RPGs was 98.2%. The overall complication rate for RPG was 12.7% (10.9% minor and 1.8% major).

CONCLUSIONS

RPG is a valuable tool for establishing enteral nutrition in patients with head and neck cancer. Advantages of RPG include high success rate despite obstructing lesions, low complication rate, time efficiency and scheduling ease compared with intraoperative percutaneous gastrostomy (PEG) by a second team, no reported tumor seeding of the tube site, and the fact that postoperative RPG allows for more accurate selection of patients who require a gastrostomy tube.

Stability and oligosaccharide binding of the N1 cellulose-binding domain of Cellulomonas fimi endoglucanase CenC

Differential scanning calorimetry has been used to study the thermal stability and oligosaccharide-binding thermodynamics of the N-terminal cellulose-binding domain of Cellulomonas fimi beta-1,4-glucanase CenC (CBDN1). CBDN1 has a relatively low maximum stability (delta Gmax = 33 kJ/mol = 216 J/residue at 1 degree C and pH 6.1) compared to other small single-domain globular proteins. The unfolding is fully reversible between pH 5.5 and 9 and in accordance with the two-state equilibrium model between pH 5.5 and 11. When the single disulfide bond in CBDN1 is reduced, the protein remains unfolded at all conditions, as judged by NMR spectroscopy. This indicates that the intramolecular cross-link makes a major contribution to the stability of CBDN1. The measured heat capacity change of unfolding (delta Cp = 7.5 kJ mol-1 K-1) agrees well with that calculated from the predicted changes in the solvent accessible nonpolar and polar surface areas upon unfolding. Extrapolation of the specific enthalpy and entropy of unfolding to their respective convergence temperature indicates that per residue unfolding energies for CBDN1, an isolated domain, are in accordance with those found by Privalov (1) for many single-domain globular proteins. DSC thermograms of the unfolding of CBDN1 in the presence of various concentrations of cellopentaose were fit to a thermodynamic model describing the linkage between protein-ligand binding and protein unfolding. A global two-dimensional minimization routine is used to regress the binding enthalpy, binding constant, and unfolding thermodynamics for the CBDN1-cellopentaose system. Extrapolated binding constants are in quantitative agreement with those determined by isothermal titration calorimetry at 35 degrees C.

Specific (15)N, NH correlations for residues in(15) N, (13)C and fractionally deuterated proteins that immediately follow methyl-containing amino acids

A triple-resonance pulse scheme is described which records(15)N, NH correlations of residues that immediately follow amethyl-containing amino acid. The experiment makes use of a(15)N, (13)C and fractionally deuterated proteinsample and selects for CH(2)D methyl types. The experiment isthus useful in the early stages of the sequential assignment process as wellas for the confirmation of backbone (15)N, NH chemical shiftassignments at later stages of data analysis. A simple modification of thesequence also allows the measurement of methyl side-chain dynamics. This isparticularly useful for studying side-chain dynamic properties in partiallyunfolded and unfolded proteins where the resolution of aliphatic carbon andproton chemical shifts is limited compared to that of amide nitrogens.

Diagnosing congenital heart defects using the Fallot computational model

This paper describes a computational model developed for the diagnosis of multiple defects. If multiple defects interact, meaning that the cues observable for multiple defects are not a sum of the cues observable for the component defects, diagnosis is particularly difficult. We developed a description and classification of the ways cues change when defects interact. A computational model (named Fallot) was implemented and a knowledge-base was constructed for the diagnosis of congenital heart defects. On each case, Fallot performs recognition-based reasoning followed by solution construction and evaluation with the cue combination methods. Fallot was tested on cases from hospital files and correctly diagnoses cases with multiple interacting defects for which conventional methods are not applicable or fail.

Structure of the N-terminal cellulose-binding domain of Cellulomonas fimi CenC determined by nuclear magnetic resonance spectroscopy

Multidimensional heteronuclear nuclear magnetic resonance (NMR) spectroscopy was used to determine the tertiary structure of the 152 amino acid N-terminal cellulose-binding domain from Cellulomonas fimi 1,4-beta-glucanase CenC (CBDN1). CBDN1 was studied in the presence of saturating concentrations of cellotetraose, but due to spectral overlap, the oligosaccharide was not included in the structure calculations. A total of 1705 interproton nuclear Overhauser effect (NOE), 56 phi, 88 psi, 42 chi 1, 9 chi 2 dihedral angle, and 88 hydrogen-bond restraints were used to calculate 25 final structures. These structures have a rmsd from the average of 0.79 +/- 0.11 A for all backbone atoms excluding disordered termini and 0.44 +/- 0.05 A for residues with regular secondary structures. CBDN1 is composed of 10 beta-strands, folded into two antiparallel beta-sheets with the topology of a jelly-roll beta-sandwich. The strands forming the face of the protein previously determined by chemical shift perturbations to be responsible for cellooligosaccharide binding [Johnson, P. E., Tomme, P., Joshi, M. D., & McIntosh, L. P. (1996) Biochemistry 35, 13895-13906] are shorter than those forming the opposite side of the protein. This results in a 5-stranded binding cleft, containing a central strip of hydrophobic residues that is flanked on both sides by polar hydrogen-bonding groups. The presence of this cleft provides a structural explanation for the unique selectivity of CBDN1 for amorphous cellulose and other soluble oligosaccharides and the lack of binding to crystalline cellulose. The tertiary structure of CBDN1 is strikingly similar to that of the bacterial 1,3-1,4-beta-glucanases, as well as other sugar-binding proteins with jelly-roll folds.

Interaction of soluble cellooligosaccharides with the N-terminal cellulose-binding domain of Cellulomonas fimi CenC 2. NMR and ultraviolet absorption spectroscopy

The N-terminal cellulose-binding domain (CBDN1) from Cellulomonas fimi beta-1,4-glucanase CenC binds amorphous but not crystalline cellulose. To investigate the structural and thermodynamic bases of cellulose binding, NMR and difference ultraviolet absorbance spectroscopy were used in parallel with calorimetry (Tomme, P., Creagh, A. L., Kilburn, D. G., & Haynes, C. A., (1996) Biochemistry 35, 13885-13894) to characterize the interaction of soluble cellooligosaccharides with CBDN1. Association constants, determined from the dependence of the amide 1H and 15N chemical shifts of CBDN1 upon added sugar, increase from 180 +/- 60 M-1 for cellotriose to 4,200 +/- 720 M-1 for cellotetraose, 34,000 +/- 7,600 M-1 for cellopentaose, and an estimate of 50,000 M-1 for cellohexaose. This implies that the CBDN1 cellulose-binding site spans approximately five glucosyl units. On the basis of the observed patterns of amide chemical shift changes, the cellooligosaccharides bind along a five-stranded beta-sheet that forms a concave face of the jelly-roll beta-sandwich structure of CBDN1. This beta-sheet contains a strip of hydrophobic side chains flanked on both sides by polar residues. NMR and difference ultraviolet absorbance measurements also demonstrate that tyrosine, but not tryptophan, side chains may be involved in oligosaccharide binding. These results lead to a model in which CBDN1 interacts with soluble cellooligosaccharides and, by inference, with single polysaccharide chains in regions of amorphous cellulose, primarily through hydrogen bonding to the equatorial hydroxyl groups of the pyranose rings. Van der Waals stacking of the sugar rings against the apolar side chains may augment binding. CBDN1 stands in marked contrast to previously characterized CBDs that absorb to crystalline cellulose via a flat binding surface dominated by exposed aromatic rings.

Probing the role of tryptophan residues in a cellulose-binding domain by chemical modification

The cellulose-binding domain (CBDCex) of the mixed function glucanase-xylanase Cex from Cellulomonas fimi contains five tryptophans, two of which are located within the beta-barrel structure and three exposed on the surface (Xu GY et al., 1995, Biochemistry 34:6993-7009). Although all five tryptophans can be oxidized by N-bromosuccinimide (NBS), stopped-flow measurements show that three tryptophans react faster than the other two. NMR analysis during the titration of CBDCex with NBS shows that the tryptophans on the surface of the protein are fully oxidized before there is significant reaction with the two buried tryptophans. Additionally, modification of the exposed tryptophans does not affect the conformation of the backbone of CBDCex, whereas complete oxidation of all five tryptophans denatures the polypeptide. The modification of the equivalent of one and two tryptophans by NBS reduces binding of CBDCex to cellulose by 70% and 90%, respectively. This confirms the direct role of the exposed aromatic residues in the binding of CBDCex to cellulose. Although adsorption to cellulose does afford some protection against NBS, as evidenced by the increased quantity of NBS required to oxidize all of the tryptophan residues, the polypeptide can still be oxidized completely when adsorbed. This suggests that, whereas the binding appears to be irreversible overall [Ong E et al., 1989, Bio/Technology 7:604-607], each of the exposed tryptophans interacts reversibly with cellulose.

Acute puerperal mastitis in the augmented breast

Acute puerperal mastitis is an inflammatory condition of the breast with an onset 2 to 3 weeks postpartum and often complicated by abscess formation in the affected breast if treatment is delayed. This case demonstrated a periprosthetic seroma in a patient who developed acute puerperal mastitis in the augmented breast that has not been described previously. Treatment of acute puerperal mastitis includes antistaphylococcal antibiotic coverage within the first 48 hours, with ultrasound examination in the presence of persistent induration, swelling, or tenderness to diagnose breast abscess. Plastic surgeons performing breast augmentation need to be aware of this entity.

New approaches to establish mineral element requirements and recommendations: an introduction

Early efforts to establish dietary recommendations were focused on defining minimum intakes of nutrients needed to prevent deficiency diseases. Although these early recommendations have proven to be successful in preventing frank deficiency diseases, new knowledge regarding the functions of nutrients at the biochemical, physiological, and gene levels has shifted the emphasis to defining the kinds and amounts of nutrients needed to optimize physiological and mental functions and to prevent or minimize the development of degenerative diseases that now are dominant public health concerns. Several challenges must be faced in producing recommendations based on this new knowledge. It must be recognized that nutrients are not consumed in isolation from one another, and interactions between a single nutrient and other nutrients and nonnutrients in foods will need to be taken into account when making dietary recommendations for that nutrient. Another factor that will influence dietary recommendations is the genetic variation of humans. New knowledge regarding the effects of genetic variability on human metabolism will ultimately lead to the development of dietary recommendations that address genetic influences on the nutritional needs of specific segments of our population.

The pKa of the general acid/base carboxyl group of a glycosidase cycles during catalysis: a 13C-NMR study of bacillus circulans xylanase

The 20 kDa xylanase from Bacillus circulans carries out hydrolysis of xylan via a two-step mechanism involving a covalent glycosyl-enzyme intermediate. In this double-displacement reaction, Glu78 functions as a nucleophile to form the intermediate, while Glu172 acts as a general acid catalyst during glycosylation, protonating the departing aglycone, and then as a general base during deglycosylation, deprotonating the attacking water. The dual role of Glu172 places specific demands upon its ionization states and hence pKa values. 13C-NMR titrations of xylanase, labeled with [delta-13C]glutamic acid, have revealed pKa values of 4.6 and 6.7 for Glu78 and Glu172, respectively. These agree well with the apparent pKa values obtained from a study of the pH dependence of kcat/Km and demonstrate that, at the enzyme's pH optimum of 5.7, the nucleophile Glu78 is deprotonated and the general acid Glu172 initially protonated. Remarkably, the pKa for Glu172 drops to 4.2 in a trapped covalent glycosyl-enzyme intermediate, formed by reaction with 2', 4'-dinitrophenyl 2-deoxy-2-fluoro-beta-xylobioside [Miao et al. (1994) Biochemistry 33, 7027-7032]. A similar pKa is measured for Glu172 when a glutamine is present at position 78. This large decrease in pKa of approximately 2.5 units is consistent with the role of Glu172 as a general base catalyst in the deglycosylation step and appears to be a consequence of both reduced electrostatic repulsion due to neutralization of Glu78 and a conformational change in the protein. Such "pKa cycling" during catalysis is likely to be a common phenomenon in glycosidases.

Validation of highly discriminating multiplex short tandem repeat amplification systems for individual identification

Short tandem repeat (STR) loci are routinely employed for individual identification. WE have examined the performance and reproducibility of a highly informative co-amplification system containing the tetranucleotide STR loci: HUMVWFA31/A, HUMTH01, D20S85, D8S1179, HUMFIBRA, D21S11, and D18S51, in conjunction with the amelogenin sex test, in addition to a modified system omitting the locus D20S85. Polymerase chain reaction (PCR) products were fluorescently detected on an automated sequencer and automatically sized against an internal size standard by Genescan software. Both systems were routinely able to type 500 pg of undegraded DNA. At DNA concentrations between 50-500 pg, partial profiles were produced, but no allelic drop-out was observed. Balanced amplification of all loci occurred over a wide range of DNA concentrations from 50 pg to 10 ng. Alteration of reagent concentrations and cycling parameters from optimal resulted in variation in the efficiency of individual locus amplification relative to the other loci within the system. This was also observed at high ionic strength or extreme pH. However, at all reagent concentrations and conditions, allelic drop-out was not observed. These multiplex systems have potential in both routine forensic and intelligence database applications.

Refining silicone implant correction of pectus excavatum through computed tomography

Silicone implant correction of pectus excavatum has yielded satisfactory results in asymptomatic patients. Problems have been encountered with accurate implant fabrication and fit due to the soft-tissue masking of actual sternal contours. We have employed computed tomography to reconstruct the pectus deformity to improve implant design and fit. Instability can be prevented with the reduced need for intraoperative manipulation as well.