Calculated stress-shielding in the distal femur after total knee replacement corresponds to the reported location of bone loss

This study sought to determine the similarities between features of calculated stress-shielding and observed bone loss in the distal femur after total knee replacement. Stress-shielding was determined by comparing the magnitudes and distributions of strain energy density, calculated using three-dimensional finite element models of the intact bone, the bone after total knee replacement with bonding assumed at all prosthesis-bone interfaces, and the bone after total knee replacement with bonding assumed only at the distal interface. The loading condition simulated static lifting with the knee flexed at 45 degrees, producing tibiofemoral and patellofemoral joint reactions of 900 and 450 N, respectively. The maximum magnitudes of strain energy density calculated using the total knee replacement models were less than 15% of the corresponding magnitudes from the intact bone model. The greatest difference was found to occur at the anterior distal corner of the femur, suggesting this location as the one most vulnerable to stress-shielding. Clinically observed bone loss after total knee replacement frequently occurs at this location. At the anterior distal corner, the calculated magnitudes for the two total knee replacement models were similar, suggesting that stress-shielding at this location was not reduced by limiting fixation only to the distal interface. Although the study corresponded to one loading condition and one geometry of the total knee replacement femoral component with the inherent limitations of model calculations, the results suggest a possible scenario for stress-shielding.

Separation of tryptophan and related indoles by micellar electrokinetic chromatography with KrF laser-induced fluorescence detection

Micellar electrokinetic chromatography (MEKC) was applied for the separation of tryptophan and related indoles. Using a 5 mM sodium borate buffer (pH 9.2) containing 50 mM sodium dodecyl sulfate and 5% acetonitrile, eleven indoles were baseline separated in under 17 min. Most of the indoles were detected at the nM level by native fluorescence using KrF laser-induced fluorescence (LIF), which was approximately 100 times more sensitive than UV absorption detection at 200 nm. Preliminary results show that the MEKC-LIF with direct sample injection is a feasible method for assessing indole profiles in diluted urine and serum.

Separation and detection of acidic and neutral impurities in illicit heroin via capillary electrophoresis

The separation and detection of acidic and neutral impurities in illicit heroin using capillary electrophoresis (CE) is described. Separations were achieved using charged cyclodextrin modified micellar electrokinetic capillary chromatography. The use of the anionic beta-cyclodextrin sulfobutyl ether 1V in combination with sodium dodecyl sulfate significantly increased resolution. Improved selectivity and/or sensitivity in detection was obtained using photodiode array ultraviolet and laser-induced fluorescence detection. The phenanthrene-like heroin impurities exhibit high native fluorescence under krypton-fluoride laser excitation (248 nm). The limit of detection by laser-induced fluorescence detection for one of these solutes (acetylthebaol) is 1.8 ng/ml, 500 times more sensitive than UV. This methodology is applicable to analysis of both crude and refined heroin.

Separation and detection of amino acids and their enantiomers by capillary electrophoresis: a review

Since its introduction as an analytical technique capillary electrophoresis has been used for the separation of amino acids and their enantiomers; over 150 studies have been published to date. This review deals with their separation and detection. Amino acids have been resolved using both capillary zone electrophoresis and micellar electrokinetic chromatography. Pre-column derivatization schemes which are employed for the sensitive detection of amino acids are discussed. Criteria for the selection of the pre- or post-column derivatizing agent, chromophore or fluorophore, are presented. Detection systems, direct and indirect, that have been used are given with emphasis on fluorogenic reagents and laser induced fluorescence detection. Also, procedures for the separation of amino acid enantiomers are discussed and illustrated.

Enantiomeric separation of amino acids using micellar electrokinetic chromatography after pre-column derivatization with the chiral reagent 1-(9-fluorenyl)-ethyl chloroformate

Direct enantiomeric separations of some racemic amino acids derivatized with 9-fluorenylmethyl chloroformate were obtained using cyclodextrin-modified micellar electrokinetic chromatography (CD/MEKC) with a buffer made up of 5 mM sodium borate (pH 9.2), 150 mM sodium dodecyl sulfate (SDS) and 40 mM gamma-CD. Alternatively, enantiomeric separations were also achieved indirectly using MEKC after pre-column derivatization with (+)-1-(9-fluorenyl) ethyl chloroformate (FLEC). Using either a 10 mM sodium phosphate (pH 6.8) or a 5 mM sodium borate buffer (pH 9.2), each of which contained 25 mM SDS and 10-15% of acetonitrile, FLEC-derivatized serine, alanine, valine, methionine, leucine, phenylalanine, tryptophan, and their diastereomeric pairs were all separated: the L-isomers migrated faster than the corresponding D-isomers. However, when (-)-FLEC was used for derivatization, the D-isomers migrated faster than the corresponding L-isomers. Also, the diastereomers of aspartic acid, glutamic acid, and proline were resolved using a 10 mM sodium citrate buffer (pH 4.4). Using KrF (248 nm) laser-induced fluorescence, the detection limit of (+)-FLEC derivatized DL-amino acids was obtained at the nM level, which was about 100 x more sensitive than UV absorption at 200 nm. Analyte concentrations as low as 3 x 10(-8) M (DL-Val) could be derivatized with (+)-FLEC.

Separation of estrogens by micellar electrokinetic chromatography

Capillary electrophoresis of the sex hormone estrogens using different buffer components was investigated. Free zone electrophoresis with 10 mM phosphate buffer (pH 11.5) or 10 mM phosphate buffer with 10-20% methanol was not effective in separating the ten estrogens used in this study. However, nine estrogens were resolved by micellar electrokinetic chromatography using a 10 mM borate buffer (pH 9.2) containing 100 mM sodium cholate. In addition, some estrogens were partially separated using sodium dodecyl sulfate (SDS) micellar buffers; however, the addition of modifiers such as organic solvents or cyclodextrins improved resolutions significantly. Using a 10 mM phosphate buffer (pH 7.0) containing 50 mM SDS and 20% methanol, or a 10 mM borate buffer (pH 9.2) containing 50 mM SDS and 20 mM gamma-cyclodextrin, all ten of the tested estrogens were separated. However, the cyclodextrin-modified buffer allowed faster separation.

Extracorporeal membrane oxygenation and the treatment of critical pulmonary hypertension in congenital heart disease

Certain forms of congenital heart disease (CHD) confer a high risk for the development of severe pulmonary hypertension before and after corrective cardiac surgery. Extracorporeal membrane oxygenation (ECMO) has theoretical benefits in the treatment of this complication in that it assures oxygenation, corrects acid-base balance and provides haemodynamic support at the same time as allowing lung rest from ventilation. We examined our experience of the 117 children and neonates supported with ECMO between November 1989 and July 1993. Of these, five received support for critical pulmonary hypertension associated with congenital heart disease. They comprised three who had undergone surgical repair of CHD, one whose total anomalous pulmonary venous drainage was diagnosed and corrected whilst on ECMO and one neonate with functional pulmonary atresia. Pulmonary artery pressure (PAP) was estimated by Doppler echocardiography in all patients and confirmed invasively in two. The median systolic PAP was 46 (range 42-65) mmHg prior to ECMO. The median ratio of pulmonary to systemic arterial pressure (PAP/SAP) was 0.75 (0.70-0.92). Following ECMO of 16-120 h duration, the median systolic PAP was 34 (30-49) mmHg with PAP/SAP 0.50 (0.35-0.60). All patients survived and there were no complications related to ECMO. Extracorporeal membrane oxygenation is an effective treatment in critical pulmonary hypertension and should be considered in all patients in whom this is refractory to conventional measures.

Micellar electrokinetic chromatography of the anti-human immunodeficiency virus (HIV) agent michellamine B with absorption and laser-induced fluorescence detection

Micellar electrokinetic chromatography (MEKC) was applied to the separation of the anti-HIV agents, michellamines A and B, and two other structurally related monomers found in the extract of the Ancistrocladus plants. Using buffers containing either 10 mM sodium phosphate (pH 7.0), 50 mM sodium deoxycholate and 10-20% acetonitrile or 5 mM sodium phosphate (pH 7.0), 20 mM sodium dodecyl sulfate and 25% acetonitrile allowed baseline separations of the four components in the mixture in less than 10 min. The MEKC methods gave sharper peaks and better resolution compared to high-performance liquid chromatography. For MEKC separation of the plant extracts, UV absorption detection provided adequate sensitivity; however, higher sensitivity could be achieved with UV laser-induced fluorescence detection (LIF). Using the sodium dodecyl sulfate-containing buffer and LIF, the limit of detection for michellamine B was approximately 2 ng/mL. The sensitivity was degraded approximately 100-fold when using the deoxycholate buffer because of high background fluorescence. Preliminary results show that MEKC with LIF is feasible for the sensitive detection of michellamine B in serum.

Marginal seal of new-generation dental bonding agents

This in vitro study evaluated microleakage of three new adhesive systems--All-Bond 2, Gluma 2000, and Scotchbond Multi-Purpose. Enamel was removed from the buccal surfaces of 40 extracted molars, and cavity preparations were made on both the buccal and lingual surfaces of each tooth. Buccal cavities were entirely in dentin, and the lingual cavities had enamel margins. Specimens were randomly assigned to three groups for treatment with All-Bond 2, Gluma 2000, or Scotchbond Multi-Purpose adhesive systems. A fourth group of specimens was untreated to serve as the control. All cavity preparations were restored with a visible light-cured microfilled composite resin. Specimens were thermocycled and subjected to a crystal violet staining technique to detect marginal microleakage. Microleakage was recorded as ordinal data and analyzed with nonparametric statistical tests. Each of the adhesives tested significantly reduced microleakage at the enamel and dentin margins. The extent of leakage at dentin margins was only slightly greater than at enamel margins in each treatment group.

Incomplete forms of Beckwith-Wiedemann syndrome: report of a case

Beckwith-Wiedemann syndrome is a rare disease characterized by a constellation of congenital and time-dependent abnormalities such as defects of the abdominal wall, gigantism, craniofacial dysmorphism, visceromegaly and hemihypertrophy. The syndrome is divided into complete and incomplete forms and, as it may only have subtle phenotypic features, it is easily neglected by clinicians. Patients with this syndrome, particularly those associated with hemihypertrophy, have a high risk of growing malignant tumors. This is a case report of a patient with an incomplete form of this syndrome with left hemihypertrophy, hepatosplenomegaly and a small right adrenal cystic lesion.

Right ventricular outflow reconstruction with cryopreserved homografts in pediatric patients: intermediate-term follow-up with serial echocardiographic assessment

OBJECTIVES

This study was performed to assess by echocardiography the intermediate-term outcome of cryopreserved homografts employed in pulmonary outflow reconstruction in children and to validate the reliability of Doppler echocardiography in their evaluation.

BACKGROUND

Cryopreserved homografts have become the most widely used pulmonary conduits. Previous reports have shown the occurrence of homograft regurgitation in the immediate postoperative period and the propensity of regurgitation to progress. Although Doppler echocardiography has been useful in assessing extracardiac valved conduit stenosis, its reliability in assessing a large series of cryopreserved homografts has not been documented.

METHODS

Echocardiograms of 41 patients (43 homografts) who underwent operations between December 1986 and October 1992 were retrospectively reviewed. The median age of patients at operation was 37.5 months (range 3 to 333), and the median duration of follow-up was 28.5 months (range 1 to 68). Homograft regurgitation was classified on a scale of 0 to 4+. Pressure gradients across the homografts measured in 23 catheterizations were correlated with corresponding echocardiographic gradients.

RESULTS

Regurgitation: Homograft regurgitation occurred in 100% of patients at follow-up. Progression of severity > 2 grades occurred during follow-up in 35% and was associated with operation before age 18 months (p < 0.002) and stenosis progression (p < 0.05) but not with homograft type (aortic or pulmonary). These data predict that 50% of patients operated on before 18 months of age will have severe regurgitation by 15 months postoperatively compared with only 15% operated on after 18 months. Stenosis: At follow-up, 51% of homografts had a stenotic gradient > or = 25 mm Hg predominantly at the distal anastomosis, and stenosis progression was related to young age at operation (< 18 months, p < 0.005) and small conduit size (p < 0.01). Fifty percent of conduits implanted before age 18 months could be predicted to stenose by 21.8 months compared with only 5% of those implanted after age 18 months. The gradient measured from Doppler echocardiography correlated well with the catheterization gradient (r = 0.86).

CONCLUSIONS

Cryopreserved homograft dysfunction is frequent and progressive. Young age at operation (< 18 months) predicts more rapid deterioration. Doppler echocardiography is reliable in assessing the systolic gradients across homografts. Serial echocardiographic assessment in the follow-up of these patients accurately characterizes these problems.

High-performance liquid chromatography and micellar electrokinetic chromatography of taxol and related taxanes from bark and needle extracts of Taxus species

High-performance liquid chromatography (HPLC) and micellar electrokinetic chromatography (MEKC) were applied for the separation of taxol, cephalomannine, and baccatin III in crude extracts from the needle and bark of Taxus species. The chromatogram of the bark extract was cleaner than that of the needle allowing a more reliable detection of taxol and cephalomannine in the bark extract. However, HPLC quantitation of taxol in the needle extract would be difficult due to coeluting taxinines. Nevertheless, this was not a problem in the MEKC experiment. In comparison to HPLC, MEKC offered baseline resolution of taxol from taxinines in the needle extract, less solvent waste, a smaller sample requirement, and the simultaneous detection of taxol, cephalomannine and baccatin III in a relatively simpler electrophoretic run.

Analysis of nitrate and nitrite in water and urine by capillary zone electrophoresis

A capillary zone electrophoresis method for the separation and analysis of nitrate and nitrite in water and urine was developed. No interference in the electropherogram from other anions is observed by using a polyacrylamide-coated column with a modified phosphate buffer at pH 3 for the separation, and UV absorption at 214 nm for the detection. The method does not require sample pretreatment or the use of organic solvents. The limit of detection for each analyte (S/N = 3), using a 75 microns I.D. capillary, is 0.5 microgram/ml. Urine samples require 40-fold dilution in order to maintain migration time reproducibility to within 1% relative standard deviation.

Characterization of rat serum insulin-like growth factor-binding proteins by two-dimensional gel electrophoresis: identification of a potentially novel form

The insulin-like growth factor-binding proteins (IGFBPs) in rat serum were analyzed by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western ligand or immunoblotting. A ligand blot of adult female rat serum revealed at least 20 proteins that bound labeled IGF-I specifically. They ranged in size from about 24-50K, and their pI values ranged from approximately 5.5-8.0. Immuno- and ligand blots showed that IGFBP-3 appeared as a broad band composed of numerous individual spots of about 40-45K, with pI values ranging from about 5.5-7.7. Immunoblots showed that IGFBP-4 resolved into at least three spots of approximately 29K, with pI values of about 6.3-6.7 and an approximately 24K nonglycosylated form that usually appeared as a single spot with a pI of about 7, but occasionally it resolved into a doublet. Immunoblots of neonatal rat serum using antiserum to IGFBP-2 resulted in immunoreactivity of two sets of proteins: approximately 33K forms composed of two proteins and approximately 30K forms comprising at least five different variants with pI values of about 7.0-7.5. However, ligand analysis showed that only the 30K forms had binding activity. IGFBP-1, -5, and -6 were not detectable by immunoblotting. However, a set of about 29K IGFBPs with pI values of approximately 5.9, which appears in significant amounts in the serum of pups and diabetic rats and in placental tissue-conditioned medium, has been tentatively identified as IGFBP-1 by ligand blotting. One finding of particular interest is an approximately 50K BP with a pI of about 6 that comigrates with IGFBP-3. However, unlike IGFBP-3, which is glycosylated and undergoes proteolysis during gestation, this approximately 50K IGFBP is not susceptible to endoglycosidase-F treatment and persists throughout pregnancy. Immunoblotting analysis revealed weak cross-reactivity between the approximately 50K IGFBP and antiserum to IGFBP-4. These results show that the rat serum IGFBPs are more heterogeneous than was previously realized. The two-dimensional system will allow changes in these different forms to be evaluated critically in different physiological and experimental states.

Effect of third-order dispersion on soliton-effect pulse compression

The effect of third-order dispersion on soliton-effect pulse compression is investigated. We show that third-order dispersion causes severe degradation in dispersion-shifted fibers in the compression of high-order soliton pulses. As much as an 80% reduction is found in the optimum compression ratio of 15th-order solitons of 1-ps width. We also show that fiber loss cannot be neglected in soliton-effect compression schemes, which gives rise to an initial pulse-width dependence in the compression ratio and to the existence of an optimum initial width.

Micellar electrokinetic chromatography of hydroxyproline and other secondary amino acids in biological samples with laser-induced fluorescence detection

Micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence (LIF) was used for the rapid and sensitive detection of hydroxyproline in serum and hydrolyzed urine that were pre-column derivatized with 9-fluorenylmethyl chloroformate (FMOC). The application of the combined o-phthalaldehyde (OPA)/FMOC derivatization in MEKC for the selective detection of secondary amino acids in biological samples is investigated.

Separation of pyridinecarboxylic acid isomers and related compounds by capillary zone electrophoresis. Effect of cetyltrimethylammonium bromide on electroosmotic flow and resolution

The effect of the addition of cetyltrimethylammonium bromide (CTAB) to the buffer system in capillary electrophoresis on electroosmotic flow (EOF) is examined. At a CTAB concentration of 2.5 x 10(-4) M, EOF is anodal (flow towards the positive detector column end). With bare silica columns, anodal EOF first increases with increasing pH, up to a maximum in the pH range 4-6 depending on CTAB concentration, then decreases as pH is further increased. Optimum resolution of pyridinecarboxylic acid isomers is obtained at pH 2.7 with a 10 mM phosphate buffer and 30 mM CTAB. Using the same buffer system, optimum resolution for hydroxy-substituted pyridinecarboxylic acid isomers is obtained at pH 7.5. The use of CTAB results in a dramatic improvement in peak shape. Preliminary results, using an excimer laser operated at 248 nm, show that the fluorescence intensity of isonicotinic acid is substantially enhanced with the addition of 0.3% hydrogen peroxide to the phosphate buffer system.

Laser-induced fluorescence detection of 9-fluorenylmethyl chloroformate derivatized amino acids in capillary electrophoresis

Laser-induced fluorescence (LIF) was applied to the detection of 9-fluorenylmethyl chloroformate (FMOC-Cl) derivatized amino acids separated by capillary electrophoresis. Fluorescence excitation was provided by a pulsed, KrF laser operating at 248 nm. A limit of detection of 5 x 10(-10) M was obtained for FMOC-alanine (S/N = 2). Separation of FMOC-derivatized proline, hydroxyproline, and sarcosine was achieved with a 20 mM borate buffer (pH 9.2), and the separation of FMOC-derivatized amino acid standard mixture was obtained using a 20 mM borate buffer (pH 9.2) containing 25 mM sodium dodecyl sulfate.

Repair of newly condensed amalgam restorations

This study investigated the tensile strength of the newly condensed amalgam repaired with newly triturated amalgam in different times. A separable plexiglass mold with a dumbbell shape "cavity" was prepared. Amalgam was condensed in the "cavity" and allowed to set for one hour before it was removed from the mold and used for control. Five controls were prepared. Five groups with five samples in each group were prepared. Amalgam was condensed in the first half of the "cavity" and 5, 15, 30, 60 minutes and 24 hours later newly triturated amalgam was condensed in the second half of the "cavity" for the 5, 15, 60 minutes and 24 hour group samples. All samples were allowed to set in the mold for one hour then removed and stored in 100% humidity condition at room temperature for 24 hours. Tensile strength was tested on the Instron testing machine. It was found that when the newly condensed amalgam was repaired in five minutes, it has 84% of the tensile strength and was not significantly different from the controls. When it was repaired in 15, 30, 60 minutes and 24 hours, the tensile strength was significantly lower than the controls and significantly different from the controls.

High casein-lactalbumin diet accelerates blood coagulation in rats

This study investigates the influence of a high protein intake on normal hemostasis, fluid balance and organ growth. Adult rats were fed semipurified diets that contained either 18 or 56 g/100 g casein-lactalbumin for 2 wk, and the following functions were measured: food and water intake, weight gain, blood pressure, bleeding and clotting time, ADP-stimulated platelet aggregation, thrombin time, prothrombin time and partial thromboplastin time. Although food intake was depressed by the high protein diet, weight gain was not affected by the regimen. Water consumption, 24-h urine excretion and kidney weight were significantly greater in rats fed the high protein diet than in controls. High protein intake resulted in shorter barbiturate-induced sleeping time. Bleeding time and clotting time were significantly lower in rats fed the high protein diet for 7 d. However, heart rate, mean arterial pressure, plasma protein and osmolarity, platelet aggregation, prothrombin time, partial thromboplastin time and thrombin time did not differ significantly. Because a high protein intake caused rapid coagulation of blood in rats without affecting the activity of clotting factors, we suggest that this diet sensitized rats to factors that initiate clotting in vivo.

Radiofrequency-assisted balloon dilatation in patients with pulmonary valve atresia and an intact ventricular septum

OBJECTIVE

To investigate the efficacy and safety of transcatheter radiofrequency-assisted valve dilatation for infants with pulmonary valve atresia and intact ventricular septum as an alternative to the use of laser heated wires.

DESIGN

Prospective clinical study.

SETTING

Three paediatric cardiology centres.

PATIENTS

Four children (aged 5-101 days, weight 2.8 kg) with pulmonary valve atresia and intact ventricular septum underwent percutaneous radiofrequency-assisted valve dilatation.

METHODS

After delineating the atretic valve by angiography, 0.020 inch or 0.018 inch radiofrequency wires were used to perforate the atretic valve. The valve was then dilated with conventional balloon dilatation catheters up to the valve annulus diameter.

RESULTS

In all four cases the radiofrequency wire perforated the atretic pulmonary valve and balloon dilatation was successful. In one patient the radiofrequency wire also passed through the anterior wall of the pulmonary artery causing tamponade which required surgical repair shortly afterwards. This patient died from sepsis six days later. One patient died three weeks after the procedure from septicaemia and a paradoxical coronary embolus. Two patients were discharged after 4 and 14 days respectively.

CONCLUSIONS

Radiofrequency-assisted valve dilatation is a promising alternative to the recently developed laser wire technique. The major advantages are a reduction in cost and improved safety for the staff performing the procedure.

Morphological variations of fossa ovalis atrial septal defects (secundum): feasibility for transcutaneous closure with the clam-shell device

OBJECTIVE--To assess the morphology of fossa ovalis atrial septal defects (FOASD; secundum atrial septal defect) to determine in what proportion percutaneous closure with the clam-shell device might be feasible. DESIGN--Review of the intraoperative description of the morphology and size of FOASD. PATIENTS--106 consecutive patients with FOASD. SETTING--A regional children's cardiac referral centre. MAIN OUTCOME MEASURES--Determination of morphology and size of FOASD. RESULTS--Morphological variations in the FOASD were found: (1) central FOASD, 70 (66%); (2) superior FOASD, 4 (3.7%); (3) inferior FOASD, 8 (7.6%); (4) posterior FOASD, 2 (1.9%); (5) subtotal absence of atrial septum, 3 (2.8%); (6) completely fenestrated FOASD, 10 (9.4%); (7) partially fenestrated FOASD, 9 (8.5%). Depending on its site, the edge of the FOASD may be close to important atrial structures such as the orifices of the superior and inferior caval veins, coronary sinus, and right pulmonary veins. The shape of the FOASD was usually oval with the major diameter ranging from 10 to 50 mm with a mean (SD) of 27.8 (0.93) mm. The minor diameter ranged from 4 to 30 mm with a mean (SD) of 15.3 (5.9) mm. The ratio of the major to minor diameter ranged from 1.0 to 5.0 with a mean of 2.01. Based on intraoperative measurement and description, it is postulated that it should be possible to close about 50% of these defects with the clam-shell device.

Salvage of postoperative pulmonary hypertensive crisis using ECMO via cervical cannulation in a case of truncus arteriosus

The survival of patients with truncus arteriosus beyond one year of age is rare without surgical treatment [3 . Early surgery may be associated with a mortality but is still preferable, as the risks of established pulmonary hypertensive disease complicate delayed surgery [2]. We report the successful salvage of a pulmonary hypertensive crisis 24 h after corrective surgery in a late presenting patient using extracorporeal membrane oxygenation (ECMO) via cervical cannulation. Post-operative pulmonary hypertensive crises may present a difficult management problem. Extracorporeal membrane oxygenation is therapeutic in these circumstances in addition to providing life support. Cervical cannulation remains the method of choice in the postoperative cardiac patient.

Fetal and neonatal outcome of exposure to anticoagulants during pregnancy

We studied fetal and neonatal outcome of women maintained on anticoagulants (warfarin and/or heparin) during pregnancy. Among 22 Chinese families, 13 mothers (59%) had a history of recurrent abortion or stillbirth while being maintained on warfarin treatment. Twenty-nine liveborn children (17 boys, 12 girls), ages 0.6-11.3 years at follow-up, were analysed for evidence of embryopathy. These were subdivided into 2 groups. Group 1 consisted of 18 children (12 boys, 6 girls) whose mothers were only given warfarin during pregnancy. Five were small for gestational age, and 12 had features of warfarin embryopathy such as nasal hypoplasia. One had subependymal intraventricular hemorrhage shown on neonatal ultrasonography. Group 2 consisted of 11 children (5 boys, 6 girls) whose mothers were maintained on warfarin and heparin during pregnancy. Three were premature deliveries, and 4 had nasal hypoplasia. One had cleft lip, cleft palate, cataract, microphthalmia, intraventricular hemorrhage, and hydrocephalus. We found that despite the high risk of fetal wastage, there was a relative lower risk of major complications, except for some minor cosmetic defects such as nasal hypoplasia. This might lead to readjustment of advice concerning contraception given to pregnant women who were maintained on anticoagulant therapy.

Continuous wave Doppler echocardiography after surgical repair of coarctation of the aorta

OBJECTIVE

To find how closely pressure gradients across the aortic arch derived from Doppler echocardiography reflect gradients measured by catheter after surgical repair of coarctation of the aorta.

DESIGN

Pressure drop across the aortic arch was measured simultaneously by continuous wave Doppler and double lumen catheter in 20 patients with repaired coarctation of the aorta.

RESULTS

The peak pressure drop estimated by Doppler was almost invariably higher than the peak to peak gradient measured by catheter, as might be expected. Wide variation was seen between the Doppler measured pressure drop and instantaneous peak gradient measured by catheter, ranging from +22 to -17 mm Hg. The reasons for these differences are unclear but are probably related to a combination of complex flow dynamics in the aortic arch, difficulty in closely aligning the Doppler beam with flow, and inability to measure flow velocity immediately proximal to the site of the surgical repair with continuous wave Doppler.

CONCLUSIONS

Continuous wave Doppler echocardiography may significantly overestimate or underestimate the pressure drop after repair of coarctation and it should be interpreted with caution in individual patients. Catheterisation with angiography remains the reference standard for assessment of surgical repair of the aortic arch.

Microleakage between glass-ionomer cement and composite resins

This study investigated the microleakage between glass-ionomer cement and Silux or Herculite with and without Scotchbond 2. Cavities were prepared in polymerized composite resin samples and "restored" with a glass ionomer cement with and without Scotchbond 2. The samples were thermocycled and immersed in 0.05% crystal violet solution for 2 hours, then embedded in clear casting resin, sectioned, and examined with an optical microscope. The results indicated that a high degree of dye penetration was found in samples of GC and Silux, and GC and Herculite without Scotchbond 2. The use of Scotchbond 2 significantly reduced the degree of dye penetration, but did not completely eliminate dye penetration.

Effects of 'resin-compatible' cavity varnishes on composite resin microhardness

Although the use of cavity varnishes with composite resins has traditionally been discouraged, several "resin-compatible" varnishes are currently available. This in vitro study evaluated the effects of resin-compatible cavity varnishes on a hybrid composite resin. The results of the study indicate that these varnishes soften the composite resin in contact with varnished dentin.

Microleakage between different types of base materials

This study investigated the sealing properties of various combinations of base materials. Three chemically cured and three light-activated base materials were combinationally used to make 15 sample groups. The samples were thermocycled and immersed in 0.05% crystal violet solution for 1 hour. They were then embedded in clear casting resin, sectioned, and photographed. The interfaces of the samples were digitized. The ratio of the total interface length to the penetration of leakage was calculated and compared. The results indicated that the combination of Cavalite and VLC Dycal materials had the least microleakage and was significantly different from the other 14 groups.

Microleakage between composite resin and basing materials

This study investigated the microleakage between a composite resin restorative material and six basing materials. Cavities were prepared in polymerized composite resin samples and "restored" with Cavitec, Life, Ketac-Bond, BaseLine, Cavalite, and VLC Dycal. The samples were thermocycled and immersed in 0.05 percent crystal violet solution for 2 hours, then embedded in clear casting resin, sectioned and examined with an optical microscope. Our results indicated that Cavalite and VLC Dycal allowed no dye penetration. Cavitec and Life had a moderate degree of dye penetration and Ketac-Bond and BaseLine had a relatively high degree of penetration.

Leakage of a light-activated base: effect of dentin bonding agents

This study investigated the sealing properties of Cavalite light-activated base material in conjunction with various dentin bonding agents. Thirty extracted molars were selected and cleaned. Slot preparations with standard dimensions were made. The prepared cavities were filled with Cavalite material after application of the dentin bonding agents Gluma, Prisma Universal Bond, Scotchbond 2, and Tenure. Samples were thermocycled for 180 cycles between 3 degrees C and 60 degrees C, then immersed in 0.05% crystal violet solution for 2 hours. The samples were embedded in clear casting resin, sectioned, and examined with a light microscope. Results indicated that Cavalite material used alone, without a dentin bonding agent, allowed the greatest degree of dye penetration. Cavalite material with Tenure bonding agent had the lowest degree of leakage. Cavalite material used with Scotchbond 2, Gluma, or Prisma Universal Bond bonding agents allowed an intermediate degree of dye penetration. According to an analysis of variance, however, there was no statistical difference in the effects of Tenure, Scotchbond 2, and Gluma bonding agents.

Effect of varnishes on surface microhardness of basing materials

This study investigated the surface microhardness of five basing materials with four varnishes applied to them. Ten Plexiglass molds with 7-mm diameter holes were prepared. Basing materials of Cavitec, Life, Ketac Bond, TimeLine, and Cavalite were placed in the molds to produce 20 samples each. Copalite, Universal, Contact, and Barrier varnishes were applied to the top and bottom surfaces of the base material samples at 1 hour and 24 hours. After air drying, the surface microhardness of the samples was tested with a Micromet II microhardness tester. The surface microhardness of all the basing materials tested was reduced when varnishes were applied to them. Contact and Barrier reduced surface microhardness value more than Copalite and Universal.

Effect of the tenure dentin bonding system on leakage of light-activated liners

This study investigated the effect of the Tenure dentin bonding system on the sealing properties of four light-activated liners. Dentinal slot preparations were made in extracted human molars and "restored" with Cavalite, TimeLine, VLC Dycal, and Zionomer liners. Samples were immersed in 0.05 percent crystal violet solution for 2 hours, then embedded in clear casting resin, sectioned, and examined with an optical microscope. Our results indicated that the Tenure dentin bonding system reduced dye penetration around each of the light-activated liners tested. The Tenure/VLC Dycal system provided a more effective seal than the other liners.

Microleakage of seven dentin bonding agents

The purpose of this study was to evaluate the ability of seven dentin bonding agents to reduce dye penetration at the margins of microfill composite restorations in dentinal cavities. Forty extracted molars were selected and cleaned. Cavity preparations were made in dentin with #55 carbide burs. The preparations were restored with Silux after application of one of the following dentin bonding agents: Gluma, Scotchbond 2, Tenure, Prisma Universal Bond 2, Mirage-Bond, XR Bond, and All-Bond. Samples were thermocycled for 200 cycles between 3 degrees C and 60 degrees C, then immersed in a 0.05 percent crystal violet solution for 2 hours. The samples were embedded in clear casting resin, sectioned, and examined with a light microscope. Our results indicated that the dentin bonding systems reduced, but failed to totally eliminate, microleakage around the composite resin restorations.

Cardiovascular malformations in Malaysian neonates with Down's syndrome

A prospective study was done to determine the incidence of cardiovascular malformations in neonates with Down's syndrome. 17/34 (50%) of the babies with Down's syndrome born at the Maternity Hospital, Kuala Lumpur, Malaysia had congenital heart defects. These included 7 cases of ventricular septal defect (VSD), 3 cases of patent ductus arteriosus (PDA), 2 cases of atrio-ventricular canal defect, 2 cases of ventricular septal defect with patent ductus arteriosus, 1 case of hypertrophic cardiomyopathy, 1 case of hypertrophic obstructive cardiomyopathy and 1 case of complex cyanotic heart. Only 8/17 (47%) of these babies had any clinical signs suggesting underlying cardiac defects. In view of the common occurrence of cardiac anomalies, it is recommended that echocardiographic screening should be carried out on all neonates with Down's syndrome.

Sequential Forearm Intravenous Regional and Infiltration Anaesthesia: Value for Haemostasis

Intravenous regional anaesthesia using 0.5% lignocaine with a forearm tourniquet is a satisfactory technique for operations on the distal forearm, wrist and hand. Since recovery of pain sensation is rapid, haemostasis after release of tourniquet becomes difficult and sometimes impossible. Local wound infiltration or metacarpal block with 1% lignocaine just before release of the tourniquet can allow subsequent haemostasis and wound closure to be carried out without causing pain. 55 patients received this sequential forearm intravenous regional and infiltrative anaesthesia. Subsequent haemostasis and wound closure could be carried out without pain in 51 patients (92.7%); three patients (5.5%) noticed mild discomfort but the operations could be finished without any additional anaesthetic agent. No complications were encountered with this modified technique.

Sequential forearm intravenous regional and infiltration anaesthesia: value for haemostasis

Intravenous regional anaesthesia using 0.5% lignocaine with a forearm tourniquet is a satisfactory technique for operations on the distal forearm, wrist and hand. Since recovery of pain sensation is rapid, haemostasis after release of tourniquet becomes difficult and sometimes impossible. Local wound infiltration or metacarpal block with 1% lignocaine just before release of the tourniquet can allow subsequent haemostasis and wound closure to be carried out without causing pain. 55 patients received this sequential forearm intravenous regional and infiltrative anaesthesia. Subsequent haemostasis and wound closure could be carried out without pain in 51 patients (92.7%); three patients (5.5%) noticed mild discomfort but the operations could be finished without any additional anaesthetic agent. No complications were encountered with this modified technique.

Surgical correction of tetralogy of Fallot in the presence of Ebstein's anomaly of the tricuspid valve

The combination of tetralogy of Fallot and Ebstein's anomaly of the tricuspid valve is extremely rare. We report the case of a child with such anatomy, who underwent successful repair of tetralogy in infancy despite the tricuspid valve abnormality.

Functional aortic atresia in congenitally corrected transposition

An infant with congenitally corrected transposition and severe regurgitation through the left atrioventricular valve presented with clinical and Doppler echocardiographic features of aortic atresia. This eventually proved to be functional. This clinical situation had not, to the best of our knowledge been previously reported before.

Leakage of chemical and light-cured basing materials

This study investigated the sealing properties of chemical and light-cured basing materials in dentin. Fifty extracted molars were selected and cleaned. Slot preparations with standard dimensions were made. The prepared cavities were filled with Cavitec, Life, Ketac-Bond, VLC Dycal, and Cavalite materials. Samples were immersed in 0.05% crystal violet solution for 2 hours. The samples were then embedded in clear casting resin, sectioned, and examined with a microscope. Results indicated that Cavalite and Ketac-Bond materials allow a greater degree of dye penetration that the three other materials. Cavitec, VLC Dycal, and Life materials were similar to each other in degree of dye penetration.