Anatomical danger zone reconsidered: a micro-CT study on dentine thickness in mandibular molars.

AIM: To investigate the smallest dentine thickness in mesial canals of mandibular molars along the cervical and middle thirds of the root by means of a micro-computed tomographic (micro-CT) technology and digital image analysis. METHODOLOGY: Fifty mesial roots of mandibular molars having two independent canals (mesiobuccal and mesiolingual), in the coronal and middle levels, were selected and scanned in a micro-CT device. After reconstruction procedures, approximately 468 slices per root covering the 7 mm below the furcation area of the mesial root were analysed to measure the smallest dentine thickness (danger zone [DZ]) in each slice from both distal and mesial regions of the mesial canals by an automatic segmentation process. RESULTS: The DZ values in the mesiobuccal canals varied from 0.67 to 1.93 mm, with an average of 1.13 ± 0.21 mm. For the mesiolingual canals, the DZ varied from 0.77 to 1.89 mm with an average of 1.10 ± 0.21 mm. There was no correspondence in the DZ between the mesiobuccal and mesiolingual canals at the same cross-sectional level in 71% of the specimens. Moreover, the smallest dentine thickness was towards the mesial region of the roots in 22% and 18% of the mesiolingual and mesiobuccal canals, respectively. (Figs 1 and 2 CONCLUSIONS: The smallest dentine thickness was on the mesial plane of the roots in about 40% of the canals. The vertical location of the DZ in relation to the furcation area was in the middle third of the root.

Novel hydroxyapatite nanorods improve anti-caries efficacy of enamel infiltrants.

OBJECTIVES: Enamel resin infiltrants are biomaterials able to treat enamel caries at early stages. Nevertheless, they cannot prevent further demineralization of mineral-depleted enamel. Therefore, the aim of this work was to synthesize and incorporate specific hydroxyapatite nanoparticles (HAps) into the resin infiltrant to overcome this issue. METHODS: HAps were prepared using a hydrothermal method (0h, 2h and 5h). The crystallinity, crystallite size and morphology of the nanoparticles were characterized through XRD, FT-IR and TEM. HAps were then incorporated (10wt%) into a light-curing co-monomer resin blend (control) to create different resin-based enamel infiltrants (HAp-0h, HAp-2h and HAp-5h), whose degree of conversion (DC) was assessed by FT-IR. Enamel caries lesions were first artificially created in extracted human molars and infiltrated using the tested resin infiltrants. Specimens were submitted to pH-cycling to simulate recurrent caries. Knoop microhardness of resin-infiltrated underlying and surrounding enamel was analyzed before and after pH challenge. RESULTS: Whilst HAp-0h resulted amorphous, HAp-2h and HAp-5h presented nanorod morphology and higher crystallinity. Resin infiltration doped with HAp-2h and HAp-5h caused higher enamel resistance against demineralization compared to control HAp-free and HAp-0h infiltration. The inclusion of more crystalline HAp nanorods (HAp-2h and HAp-5h) increased significantly (p<0.05) the DC. SIGNIFICANCE: Incorporation of more crystalline HAp nanorods into enamel resin infiltrants may be a feasible method to improve the overall performance in the prevention of recurrent demineralization (e.g. caries lesion) in resin-infiltrated enamel.

Performance and morphology of intestinal mucosa of broilers fed mannan-oligosaccharides and enzymes / Desempenho e morfologia da mucosa intestinal de frangos de corte alimentados com mananoligossacarídeos e enzimas

The performance and the morphology of intestinal mucosa of broilers fed mannan-oligosaccharides (MOS) and enzymes (E) from one to 21-day-old were evaluated using 750 one-day-old chicks, assigned to a 2 x 2 + 1 factorial design - two levels of MOS (0 and 0.1 percent), two levels of E (0 and 0.05 percent) plus an antibiotic positive control diet - performing five treatments of five replications each one. MOS x E interaction was significant for both duodenal (P<0.002 and P<0.002) and ileal (P<0.04 and P<0.05) perimeters and heights of villi, being the values lower in the mucosa of birds fed non-supplemented diets. MOS based-diet determined an increase on perimeter of jejunal villi (P<0.05). Compared with antibiotic treatment group, villi perimeter (P<0.02) and height (P<0.005), and crypt depth (P<0.02) of duodenum of broiler fed MOS were higher. Broilers fed MOS and/or E did not perform better, but higher villi perimeter and height were observed in the intestinal mucosa of those birds.

Avaliaram-se o desempenho e a morfologia da mucosa intestinal de frangos de corte alimentados com mananoligossacarídeos (MOS) e enzimas (E) até os 21 dias de idade. Utilizaram-se 750 pintainhos de um dia em delineamento experimental inteiramente ao acaso, em esquema fatorial 2 x 2 + 1 (dois níveis de MOS - 0 e 0,1 por cento, dois níveis de E - 0 e 0,05 por cento e uma dieta controle positivo com antibióticos) totalizando cinco tratamentos com cinco repetições cada. A interação MOS x E foi significativa para o perímetro de altura de vilos no duodeno (P<0,02 e P<0,02) e no íleo (P<0,04 e P<0,05), sendo os valores menores observados na mucosa das aves alimentadas com dietas não-suplementadas. A dieta contendo MOS determinou aumento no perímetro dos vilos no jejuno (P<0,05). Comparado com o grupo controle positivo, o perímetro (P<0,02) e a altura (P<0,005) dos vilos e a profundidade de cripta (P<0,02) no duodeno das aves do tratamento com MOS foram maiores. As aves que consumiram dietas com MOS e/ou E não tiveram melhor desempenho, mas maiores perímetros e alturas de vilos foram observados na mucosa intestinal dessas aves.

Scabies epidemic: price and prejudice.

Scabies epidemics are not unusual, and the recommended way of stopping them is by simultaneous treatment of everybody in the facility; this has been known since the last century, when Norwegian scabies was a problem in Norway. When this is not done, scabies epidemics can smolder for months. Scabies should not spread with good infection control measures, but we learned that a good infection control service is not enough. Efforts have to be done to educate everybody in the hospital, including laundry workers, and to improve work conditions.

Postpartum acute myocardial infarction successfully treated with intravenous streptokinase--a case report.

A twenty-three-year-old woman had an acute myocardial infarction during the early postpartum period successfully treated with intravenous streptokinase. The possible mechanisms of postpartum myocardial infarction are reviewed, and the clinical implication for the use of streptokinase in this situation is discussed.

Prevalence and functional significance of transient ST-segment depression during daily life activity: comparisons of ambulatory ECG with stress redistribution thallium 201 single-photon emission computed tomographic imaging.

To assess the prevalence and functional significance of ischemic ambulatory ECG responses, we prospectively performed ambulatory ECG monitoring in 244 patients (mean age 61 +/- 10 years) referred for stress redistribution thallium 201 myocardial perfusion scintigraphy. The prevalence of ST-segment depression during ambulatory ECG was 33% among patients with a positive exercise ECG, but prevalence varied in selected patient subgroups. Among three groups with coronary artery disease (CAD), the group with ambulatory ECG ischemia (group 1) had a greater frequency of ischemic thallium responses (p = 0.07), a greater median number of reversible thallium defects (p < 0.05), and a greater summed thallium "reversibility" score (p < 0.05) than did the group with a positive exercise ECG but negative ambulatory ECG response (group 2) or that with negative exercise and ambulatory ECG responses (group 3). Exercise ST depression in group 1 versus group 2 was significantly greater (p = 0.002), occurred at a lower heart rate threshold (p = 0.002), and lasted longer after exercise (p = 0.001). Notably, one third of group 1 patients also manifested evidence of transient ischemic dilation of the left ventricle after exercise (p < 0.01 vs groups 2 and 3), a sign of severe ischemia. However, although functionally less "sick" than group 1 patients, 66% of group 2 patients and 50% of group 3 patients still had an ischemic thallium response, which was sometimes severe. Thus transient ischemia during ambulatory ECG monitoring identifies a functionally sicker cohort of patients with CAD and occurs in approximately one third of CAD patients with positive results of exercise tests. A negative ambulatory ECG response, however, does not exclude functionally significant disease among CAD patients. These results imply that caution should be applied in the interpretation of a negative ambulatory ECG response for the purpose of patient risk stratification.

Significance of dipyridamole-induced transient dilation of the left ventricle during thallium-201 scintigraphy in suspected coronary artery disease.

The occurrence and significance of transient dilation of the left ventricle during dipyridamole stress-redistribution thallium-201 scintigraphy was studied in 73 patients who underwent both dipyridamole thallium-201 study and coronary angiography. Transient dilation ratio was calculated from planar anterior images by dividing the computer-derived left ventricular area on the initial image by that of the 4-hour image. In 11 patients with normal coronary arteriograms or less than 50% coronary stenosis, the transient dilation ratio was 0.98 +/- 0.046. An abnormal transient dilation ratio was defined as greater than or equal to 1.12, representing greater than or equal to 3 standard deviations above the mean normal value. When the 15 patients with an abnormal ratio were compared with the 58 with a normal ratio, the former group had a significantly higher frequency of 3 critical (greater than or equal to 90%) coronary stenoses (33 vs 5%), higher prevalence of collaterals (67 vs 24%), more extensive myocardial reversible defects by planar (71 vs 10%) or by single-photon emission computed tomography (87.5 vs 35%) imaging and a higher incidence of dipyridamole-induced anginal chest pain (53 vs 22%). No significant difference between the 2 groups was noted with respect to age, gender, prior myocardial infarction, single or double critical coronary stenosis, dipyridamole-induced ischemic electrocardiographic response and increased lung uptake. An abnormal transient dilation ratio of greater than or equal to 1.12 was a specific marker of multivessel (87%) or 3-vessel (85%) critical coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of long-term treatment with calcium antagonists on left ventricular diastolic function in stable angina and heart failure.

The appearance of impaired left ventricular diastolic function in chronic ischemic heart disease often precedes systolic dysfunction. Myocardial ischemia and increased calcium loading have been implicated in the genesis of increased left ventricular stiffness. We have assessed the effects of long-term therapy with different classes of calcium channel-blocking drugs on left ventricular peak filling rate in patients with chronic stable angina and congestive heart failure secondary to ischemic heart disease. Therapeutic effects of nicardipine (30 mg t.i.d.), nisoldipine (10 mg b.i.d.), and verapamil (120 mg t.i.d.) (4 weeks) have been assessed on radionuclide left ventricular diastolic filling parameters in patients with chronic stable angina using placebo-controlled studies. All three drugs significantly improved exercise capacity as compared with placebo. Verapamil produced significant improvements in peak filling rate (p less than 0.005), time to peak filling rate (p less than 0.01), and first one-third filling fraction (p less than 0.005), whereas nicardipine only improved peak filling rate (p less than 0.005); neither drug altered the mean ejection fraction (n = 20). Nisoldipine did not significantly alter diastolic filling parameters or ejection fraction (n = 10). Nisoldipine and digoxin were also assessed in congestive heart failure (New York Heart Association [NYHA] classes II and III) associated with ischemic heart disease (n = 26) (open parallel design). Neither produced significant alterations in peak filling rate and ejection fraction after 3 months of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of myocardial washout rate of thallium-201 between rest, dipyridamole with and without aminophylline, and exercise states in normal subjects.

The myocardial washout rate of thallium-201 was studied in 85 subjects with a less than 5% likelihood of coronary artery disease undergoing rest (group I, n = 12), dipyridamole (group II, n = 24) and exercise (group III, n = 49) stress thallium-201 scintigraphy. Subjects receiving dipyridamole were subdivided into group IIA (n = 11), who received an aminophylline injection 10 minutes after dipyridamole infusion, and group IIB (n = 13), who did not. The mean and highest washout rate values in each of 3 segments in the anterior, 45 degrees and 85 degrees left anterior oblique views were calculated. In group II the mean washout rate of thallium-201 was similar in all segments of each view and the overall mean washout rate did not differ between the 3 views studied. There was a good correlation between the mean and highest washout rate values in individual subjects (r = 0.98, p less than 0.001). The mean +/- standard deviation myocardial 4-hour washout rate of thallium-201 (anterior view) was 10 +/- 6% in group I compared with 40 +/- 14% in group IIA (p less than 0.05 vs group I), 31 +/- 13% in group IIB (p less than 0.05 vs group I) and 54 +/- 11% in group III (p less than 0.05 each vs group IIA and group IIB, respectively). There was a wide variation in mean washout rate values in group II (range 12 to 58%), and this variation was not altered by aminophylline administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Subclinical cardiac dysfunction in acromegaly: evidence for a specific disease of heart muscle.

Acromegaly is associated with an increased cardiac morbidity and mortality, but it is not clear whether this is the result of increased incidence of hypertension and coronary heart disease or of a specific disease of heart muscle. Thirty four acromegalic patients were studied by non-invasive techniques. Seven of these patients had raised plasma concentrations of growth hormone at the time of study; three were newly diagnosed and had not received any treatment. Hypertension was present in nine (26%) but only three (9%) had electrocardiographic left ventricular hypertrophy. Echocardiography showed ventricular hypertrophy in 12 (48%) and increased left ventricular mass in 17 (68%) patients. Holter monitoring detected important ventricular arrhythmias in 14 patients. Thallium-201 scanning showed evidence for coronary heart disease in eight patients. Systolic time intervals were normal except when there was coexistent ischaemic heart disease. A comparison between 19 acromegalic patients with no other detectable cause of heart disease and 22 age matched controls showed appreciably abnormal left ventricular diastolic function in the group with acromegaly. The abnormalities shown did not correlate with left ventricular mass or wall thickness. There was no difference in diastolic function between patients with active acromegaly and those with treated acromegaly. Hypertensive acromegalic patients had worse diastolic function than hypertensive controls, suggesting that hypertension may further impair the left ventricular diastolic abnormality in acromegaly. This is the first study to find evidence of subclinical cardiac diastolic dysfunction in acromegaly and it supports the suggestion that there is a specific disease of heart muscle in acromegaly.

Responses of left and right ventricular ejection fractions to aerobic and anaerobic phases of upright and supine exercise in normal subjects.

The effects of aerobic and anaerobic exercise on ventricular performance were studied in 13 normal subjects who underwent simultaneous pulmonary gas exchange evaluation and exercise radionuclide ventriculography in the supine and upright postures. Right and left ventricular ejection fraction was measured serially at 2-minute intervals during exercise. The anaerobic threshold occurred at 74% and 80% of maximum heart rate, respectively, during upright and supine exercise. Left and right ventricular ejection fractions rose from rest to the anaerobic threshold (p less than 0.01, p less than 0.01, respectively) and there was a further increase between the anaerobic threshold and maximum exercise (p less than 0.01, p less than 0.01, respectively). The rate of rise of ejection fraction beyond the anaerobic threshold was slightly blunted compared with the rise prior to attaining the anaerobic threshold. There was no significant difference in ventricular performance between supine and upright exercise. The data demonstrate that ventricular performance increases steadily during exercise and is not limited by the conversion of aerobic to anaerobic metabolism.

Effects of carvedilol in patients with impaired left ventricular function due to ischaemic heart disease.

In this single-blind, placebo-controlled trial, carvedilol, a nonselective beta-blocking and vasodilating agent was studied in six patients with chronic stable angina. All patients had reproducible treadmill exercise time without medical treatment and developed chest pain in association with ST-segment depression (greater than 1 mm at J + 80 msec) on exercise. None had a history of rest or unstable angina or myocardial infarction within three months prior to the study. In all patients, anti-anginal medication except sublingual nitroglycerin was discontinued for 10 days. The patients entered an initial two week-phase of placebo. They then received carvedilol, 25 mg and then 50 mg twice daily for two weeks on each dose, followed by another two week-placebo-phase. Radionuclide ventriculography was performed at the end of each phase at rest and during maximal symptom-limited exercise. Bicycle ergometry was carried out in the supine position with incremental workloads. Exercise time and workload were recorded at the end of the first phase and imaging was performed at the same time and workload throughout the trial. Carvedilol produced a dose-related reduction in rest and exercise heart rate and blood pressure. Peak exercise ST-segment change was reduced by both doses of carvedilol, but this did not achieve a level of significance. After the first placebo phase all patients had abnormal left ventricular wall motion and resting ejection fraction (range: 35% to 45%). Four out of six patients had significant improvement in wall motion abnormalities, in two patients there was no change, and none developed a deterioration in abnormal wall motion.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of bevantolol and atenolol in chronic stable angina.

A randomized, double-blind, parallel-group study design was used to compare the antianginal efficacy of bevantolol (200 to 400 mg) and atenolol (50 to 100 mg) each administrated once daily for 8 weeks in 39 patients with chronic stable angina. Assessments were made using 24-hour ambulatory monitoring and treadmill exercise testing performed 22 to 24 hours after the last dose of medication. Both groups were comparable at the end of the placebo phase. In the bevantolol group, exercise time increased from 7.9 +/- 0.7 minutes with placebo to 9.3 +/- 0.7 minutes with bevantolol (mean +/- standard error of the mean) (p less than 0.05). Time to 1 mm ST depression was unaltered. Rest and exercise heart rate decreased (p less than 0.0001 and less than 0.0005, respectively) as did exercise double product (p less than 0.0001). In the atenolol group exercise time increased from 7.1 +/- 0.7 minutes with placebo to 8.2 +/- 0.8 minutes with atenolol (p less than 0.02). Time to 1 mm ST depression increased (p less than 0.005) and rest and exercise heart rate and double product decreased (p less than 0.0001 and less than 0.05, respectively). When within-group differences between placebo and active drug were compared for bevantolol and atenolol, no significant differences were detected. Both drugs were well tolerated and reduced ambulatory heart rate throughout the 24 hours. This study confirms that both bevantolol and atenolol are effective antianginal agents. Bevantolol compares well with atenolol in the treatment of patients with chronic angina, and there was a similar response to exercise testing with the 2 drugs.

Comparison of nicardipine and verapamil in the management of chronic stable angina.

Twenty-two patients with stable angina were studied in a randomised double-blind, placebo-controlled crossover trial to compare the antianginal effects of nicardipine (30 mg) and verapamil (120 mg), each given three times a day. Efficacy was assessed using treadmill exercise testing and 24-hour ambulatory electrocardiographic monitoring performed after an initial 2-week placebo phase and at the end of each 4-week active treatment period. Exercise time (mean +/- standard error of mean) increased from 7.4 +/- 0.5 min on placebo to 8.4 +/- 0.7 min on nicardipine (P less than 0.05) and to 9.9 +/- 0.7 min on verapamil (P less than 0.001). Resting heart rate was decreased by verapamil (P less than 0.002) and increased by nicardipine (P less than 0.02). Exercise heart rate was increased on nicardipine (P less than 0.005) but heart rate gain was higher on verapamil (P less than 0.01). Blood pressure and peak ST segment depression were unaltered by either drug but the time to 1 mm ST segment depression increased on both drugs. Ambulatory heart rates were lower on verapamil than on nicardipine and patient subjective preference was in favour of verapamil. This study confirms that both nicardipine and verapamil improve exercise capacity, but verapamil produces a greater improvement in exercise tolerance and indices of myocardial ischaemia whilst nicardipine is associated with an increase in the number of episodes of ST segment depression on ambulatory monitoring.

Improvement in left ventricular diastolic function in patients with stable angina after chronic treatment with verapamil and nicardipine.

A placebo-controlled double-blind randomized crossover study was carried out to assess the effects of chronic therapy with two calcium antagonists on left ventricular diastolic function in patients with stable angina. Ventricular function was assessed using equilibrium radionuclide angiography and the data was analysed using an automated algorithm. The mean +/- SD ejection fraction on placebo was 59 +/- 10% and this remained unchanged on both verapamil (59 +/- 9%; P = NS) and nicardipine (58 +/- 7%; P = NS). Verapamil increased the peak filling rate index (P less than 0.001) and first one-third filling fraction (P less than 0.005). Nicardipine increased the peak filling rate index (P less than 0.005), but did not alter the other diastolic indices. Early filling rate index was not altered by either drug. Comparison of the effects of nicardipine and verapamil revealed no significant differences in ejection fraction, peak filling rate index or early filling rate index. However, verapamil showed a greater improvement in time to peak filling rate and first one-third filling fraction (P less than 0.01, P less than 0.01, respectively) compared with nicardipine. Heart rate (P less than 0.002) and systolic blood pressure (P less than 0.01) were also lower on verapamil than on nicardipine. These data suggest that left ventricular 'relaxation' abnormalities may be detected in patients with chronic angina pectoris before systolic dysfunction becomes apparent and that these abnormalities may be partially corrected by calcium antagonists.

Effects of a new vasodilating beta-blocking drug, carvedilol, on left ventricular function in stable angina pectoris.

The effects of a new vasodilating beta-blocking drug, carvedilol, were studied in 20 patients with chronic stable angina using a single-blind, placebo-controlled protocol. Two doses of carvedilol, 25 mg twice daily and 50 mg twice daily, were compared with placebo using analysis of variance. The study design consisted of 2 weekly phases of initial placebo followed by carvedilol, 25 mg twice daily and then 50 mg twice daily, and a second placebo period. Supine rest and exercise radionuclide ventriculography was performed at the end of each phase. Carvedilol produced a significant dose-related reduction in rest and exercise heart rate and blood pressure (p less than 0.01 to less than 0.0001). Ejection fraction at rest increased significantly, from a mean (+/- standard error) of 53 +/- 3% with placebo to 58 +/- 3% with carvedilol, 50 mg twice daily, but no improvement was noted in ejection fraction on exercise. Relative, counts-based end-systolic and end-diastolic volumes were significantly reduced at rest (p less than 0.001). Rest peak filling rate index, first-third filling fraction and ejection rate index increased significantly with carvedilol. A dose-related change was observed with rest ejection fraction, peak filling rate index and ejection rate index. Exercise-induced ST-segment depression improved significantly with both doses of carvedilol compared with placebo. Carvedilol was well tolerated and produced significant hemodynamic improvement. This salutary effect on left ventricular function may confer advantages in long-term treatment of patients with chronic stable angina.