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L A Marks

Publications and source records attributed to L A Marks.

At least 19 recordsLinked to original sources
PubMed2000

Effect of maturation on the fluoride release of resin-modified glass ionomer and polyacid-modified composite resin cements.

The effect of an early water contact on the fluoride release is studied for the resin-modified glass ionomer cements (RM-GIC) GC Lining LC, PhotacBond, Vitremer and Vitrebond and for the polyacid-modified composite resins (PAM-C) Variglass and Dyract. Six months fluoride release profiles were determined in regularly renewed water (37 degrees C), for the products directly after light curing and after 24 h maturation in a humid atmosphere (85% RH). ANOVA shows that both the short-term and the long-term fluoride release of a RM-GIC are influenced by this maturation. This indicates that direct water contact for this material should be avoided. For the RM-GIC a correlation is found between the initial fluoride release process and the long-term process. For the PAM-C materials, no differences in the fluoride release are found as a function of maturation, indicating that early water contact has no effect. The amounts of fluoride released by PAM-C are low compared to RM-GIC, which can affect their caries preventive potential. The results are explained on the basis of the setting reaction of both types of materials.

Acrylic Resins↗
PubMed2000

Effect of a neutral citrate solution on the fluoride release of resin-modified glass ionomer and polyacid-modified composite resin cements.

The effect of 0.01 mol/l citrate solution at pH = 7 on the fluoride release is compared for the resin-modified glass ionomer cements (RM-GIC) GC Lining LC, PhotacBond, Vitremer and Vitrebond and for the polyacid-modified composite resins (PAM-C) Variglass and Dyract by means of the six-month fluoride release profiles at 37 degrees C. The fluoride release of both RM-GIC and PAM-C increases in the neutral citrate solution as compared to water, which can be explained by the ability of citrate to complex metal ions and hence to degrade the glass as well as the polysalt matrix of the cement. Although RM-GIC release more fluoride than PAM-C in water as well as in citrate solution, the relative increase in fluoride release upon immersion in citrate solution is most pronounced for PAM-C. Whereas for the latter citrate affects both the short-term and long-term fluoride release, for RM-GIC only the long-term fluoride release is affected. This suggests that the action of citrate increases with decreasing importance of the polysalt formation in the hardening of the material. This could be explained on the basis of the difference in the chemical properties of the cement matrix.

Acrylic Resins↗
PubMed2000

Optimizing cuff width for noninvasive measurement of blood pressure.

BACKGROUND: It is well established that indirect measurements of blood pressure made with a standard 13cm-wide cuff are erroneously high for large arms and low for small arms. To correct for this error, the American Heart Association recommends adjusting cuff width to 40% of the arm's circumference. OBJECTIVE: To test the validity of this method of correction. DESIGN: This study was a prospective, nonblinded, paired Student's t-test analysis. METHODS: Blood pressures in 50 subjects were measured directly by using a radial artery line and indirectly by the Korotkov method. For each subject multiple indirect measurements of blood pressure were made with the cuff width:arm circumference ratio varied from 30-55% in 5% increments. Error was defined as indirect blood pressure minus direct blood pressure. RESULTS: A ratio of 40% resulted in overestimation of blood pressure for most arms and with particularly high errors for small arms. The ratio producing zero mean error for the pooled study group was 46.4+/-0.7% (mean+/-SEM). Using this ratio of 46.4%, the error varied inversely with arm circumference (P<0.02), resulting in overestimation of systolic blood pressure for small arms and underestimation of systolic blood pressure for large arms. This error is comparable in magnitude, but opposite in sign, to that which occurs with a standard 13cm-wide cuff for all arms. The optimum ratio was found to be closely approximated by the relationship, cuff width=9.34 log(10) arm circumference. Using this relationship, error in systolic blood pressure was insensitive to arm circumference (r=0.04, P>0.05) and near zero. CONCLUSION: The optimum cuff width for the indirect measurement of blood pressure is not directly proportional to arm circumference, but is proportional to the logarithm of the arm's circumference.

Adult↗
PubMed1998

Fluoride release process of (resin-modified) glass-ionomer cements versus (polyacid-modified) composite resins.

The fluoride release of conventional and resin-modified glass-ionomers is reviewed and compared to that of fluoride-releasing (polyacid-modified) composite resins. Each formulation displays a typical fluoride release profile. The cumulative amount of fluoride released is described by [F]c = [F](I)t/(t + t1/2) + beta square root t for glass ionomers whether resin-modified or not, whereas for composite resins this quantity is given by [F]c = [F](I)t/(t + t1/2) + alpha t. Both equations indicate that two kinetic processes are responsible for the fluoride release profiles. The kinetic parameters [F](I), t1/2, beta and alpha depend on the formulation. On the basis of the exchange characteristics for fluoride, an attempt is made to explain the mechanisms responsible for these fluoride release processes.

Acids↗
PubMed1998

[Use of fluorides in children: recommendations of the European Academy for Pediatric Dentistry].

The European Academy of Paediatric Dentistry (EAPD) strongly endorses that fluoride use should be part of any preventive programme for the control of dental caries in children. Each child under the care of a dentist should have a carefully planned programme appropriate to the level of caries risk and age of each child. Such a preventive programme should be reevaluated at least every six or 12 months and changed according to the patient's risk and the improvement or not of his or her's overall health. It is the combination of the use of an appropriate fluoride toothpaste with good oral hygiene that is the key to good dental health. This policy document deals with guidelines for systemic use of fluorides, fluoride supplements, topical methods (varnishes, mouthrinses and gels) and toothpastes. Moreover some recommendations are given to toothpaste manufacturers.

Age Factors↗
PubMed1995

Validation of right ventricular volume measurements by magnetic resonance imaging in small hearts using a fetal lamb model.

RATIONALE AND OBJECTIVES: Cine-magnetic resonance (MR) imaging is established as an accurate method of determining cardiac ventricular volumes in adults but has not been validated for the smaller ventricular volumes found in infants. The purpose of the authors study was to evaluate the accuracy and reproducibility of MR imaging to measure small ventricle volumes. METHODS: The volume of silicone-rubber casts of the right ventricle of 11 fetal lamb hearts was measured by MR imaging using different imaging planes and slice section thicknesses and by water displacement. RESULTS: The ventricle volumes of the 11 hearts ranged from 0.45 to 3.00 mL. Accurate and reproducible values for the right ventricle volumes were obtained by MR imaging. Thin sections (3 mm) in the axial plane produced the best results. CONCLUSIONS: Based on studies in the nonmoving heart, MR imaging can accurately measure the small ventricular volumes expected in infants.

Animals↗
PubMed1993

Staged repair of pentalogy of Cantrell with tetralogy of Fallot.

We report a successful two-stage repair of tetralogy of Fallot associated with pentalogy of Cantrell. The first stage, performed in the neonatal period, consisted of repairing the omphalocele, separating the peritoneal from the pericardial cavities, and covering the heart. The second stage, performed at 6 years of age, consisted of complete intracardiac repair and placing the heart in the chest. The patient is alive and well 18 months after the operation.

Abnormalities, Multiple↗
PubMed1991

Percutaneous transluminal balloon angioplasty of stenotic standard Blalock-Taussig shunts: effect on choice of initial palliation in cyanotic congenital heart disease.

To date, attempted balloon dilation of stenotic standard Blalock-Taussig shunts has been largely disappointing. It has been suggested that this may be due to the use of balloons of insufficient diameter. Balloon dilation of stenotic Blalock-Taussig shunts was attempted with use of relatively large balloons in five patients (11 to 67 months old) with cyanotic heart disease who were becoming progressively cyanotic and polycythemic (hemoglobin 17.9 +/- 1.1 g/dl) because of discrete shunt stenosis at the site of pulmonary anastomosis. Balloon diameters selected were equal to or within 1 mm of the unobstructed proximal shunt diameter. Before balloon dilation the diameter at the site of the stenosis was 2.8 +/- 0.8 mm (range 1.7 to 4); after balloon dilation it was 5.7 +/- 1.1 mm (range 4.5 to 7.5). The diameter increased in all patients (range 2.0 to 3.5 mm); the mean increase was 2.8 +/- 0.2 mm (p less than 0.005). Expressed as a percent, the increase in diameter at the stenosis ranged from 80% to 182.4% (mean 108.2 +/- 16.8%). Before balloon dilation the systemic oxygen saturation was 72.8 +/- 9.2% (range 55% to 80%) and after balloon dilation it was 83.6 +/- 2.9% (range 80% to 87%). A satisfactory increase (range 6% to 25%) in blood oxygen saturation was seen in all patients; the mean increase was 10.8 +/- 3.2% (p less than 0.01). At follow-up, the oxygen saturation by pulse oximetry was 85.8 +/- 2.9% (mean 5.8 +/- 1.7 months after balloon dilation) and the hemoglobin was 15.6 +/- 1.9 g/dl (mean 6.6 +/- 1.5 months after balloon dilation).(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1985

Erythromycin-sulfisoxazole vs amoxicillin in the treatment of acute otitis media in children. A double-blind, multiple-dose comparative study.

A fixed combination of erythromycin ethylsuccinate and sulfisoxazole acetyl (erythromycin-sulfa) was compared with amoxicillin for the treatment of acute otitis media (AOM) in children. Of 145 patients studied, 76 boys and 69 girls were compliant and were evaluated for drug efficacy (72 amoxicillin, 73 erythromycin-sulfa). Based on otoscopic and tympanometric results, cure rates at ten to 14 days for AOM due to all organisms were 83% (63/72) for amoxicillin and 89% (65/73) for erythromycin-sulfa; for Haemophilus species (including mixed infections), they were 84% for amoxicillin (26/31) and 83% for erythromycin-sulfa (20/14). Cure rates for ampicillin-resistant Haemophilus were 1/1 for amoxicillin and 7/8 (88%) for erythromycin-sulfa; one patient (12%) had persistent AOM at day 10. Of the patients with AOM due to Streptococcus pneumoniae, 82% (29/35) in the amoxicillin-treated group and 98% (39/40) in the erythromycin-sulfa-treated group were cured. Patients with S pneumoniae as the initial infecting organism who were treated with amoxicillin had significantly more clinical recurrences then their erythromycin-sulfa-treated counterparts, 66% (8/12) vs 33% (3/9). There was no difference between treatment groups in recurrence rates for patients with Haemophilus as the initial infecting organism. On the treatment day indicated, the following number of patients had middle ear effusion: by days 10 to 14, 38% (27/72) amoxicillin-treated patients and 48% (35/73) erythromycin-sulfa-treated patients; by day 28, 10% (7/71) amoxicillin-treated patients and 16% (11/70) erythromycin-sulfa-treated patients. There were no significant differences in adverse reactions. The erythromycin-sulfa combination is safe and effective treatment for AOM, including ampicillin-resistant Haemophilus.

Acute Disease↗
PubMedDate not supplied

Familial occurrence of discrete subaortic membrane.

The first case of multiple family members with discrete subaortic membrane and no other congenital defects is presented. One family member presents with findings suggesting a forme fruste of this disease. Increased surveillance of family members of individuals with discrete subaortic membrane is warranted, as the clinical findings of mild subaortic obstruction may be indistinguishable from those of an innocent flow murmur.

Adult↗
PubMedDate not supplied

Shots and shunts.

Explore the source record for details and available documents.

Aortography↗
PubMedDate not supplied

Evaluation of magnetic resonance imaging in coarctation of the aorta: the importance of multiple imaging planes.

Coarctation of the aorta can be evaluated reliably and noninvasively by magnetic resonance imaging. However, the value of different imaging planes in the evaluation of restenosis or aneurysm has not previously been studied. Our purpose was to study the relative sensitivity for oblique coronal and oblique parasagittal magnetic resonance imaging to detect restenosis or aneurysm formation in children following surgical repair or balloon angioplasty of coarctation of the aorta. The study included magnetic resonance imaging studies in 27 children. Each exam included ECG gated, spin-echo imaging in oblique coronal and oblique parasagittal planes. Recoarctation was defined as a greater than 50% narrowing of the aorta. Aneurysms were defined as focal dilatation of the aorta in the region of coarctation 20% or greater than the adjacent aortic diameter. Recoarctation was detected in 11 children, but in both views in only five children. Aneurysms were detected in 15 children, but in both views in only three children. Recoarctation and aneurysm detection were both statistically more likely to be detected if oblique coronal and oblique parasagittal views were obtained, indicating that multiple imaging planes are necessary to completely evaluate magnetic resonance imaging of coarctation.

Angioplasty, Balloon↗
PubMedDate not supplied

Dyract versus Tytin Class II restorations in primary molars: 36 months evaluation.

Due to the changed treatment approach of proximal caries and the amalgam controversy, clinicians are in search for new materials. The aim of the present study was to compare amalgam with an adhesive material in deciduous molars in a clinical, split-mouth design study. At baseline 30 polyacid modified composite (Dyract) and 30 amalgam (Tytin) restorations were placed in primary molars, of which 24 and 17 could be evaluated after 24 and 36 months, respectively. Modified USPHS criteria were used for clinical evaluation every 6 months. Annual bite-wing radiographs were taken for evaluation of recurrent caries and cervical gap formation. In the present study, for Dyract as well as for Tytin restorations, low rates of recurrent caries were found, while Dyract restorations showed a better marginal adaptation and surface texture compared to Tytin restorations. In the Dyract group more radiolucencies were found at baseline. In both groups no patient complaint or pain was reported related to the radiolucencies. After 3 years the colour of Dyract was not comparable to the original. For Dyract no excessive wear was noticed compared to enamel. During the study one Dyract (recurrent caries: 18 months) and two Tytin (pulpal aetiology: 6 months, recurrent caries: 36 months) restorations had to be replaced. Even though the restorations were placed in caries risk children, at the 36 months' evaluation of this clinical study, the results indicate that Dyract can be an alternative for Tytin in the primary dentition.

Child↗