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Biomedical subjects

C E Brown

Publications and source records attributed to C E Brown.

At least 73 records · Page 4Linked to original sources
PubMed1991

The comparative antimicrobial effect of calcium hydroxide.

The antimicrobial effectiveness of calcium hydroxide, camphorated paramonochlorophenol, and formocresol in root canals of extracted human teeth was compared. Canals in single-rooted teeth were enlarged and inoculated with Streptococcus mutans, Actinomyces viscosus, and Bacteroides gingivalis or Bacteroides fragilis. After treatment with a test agent and sealing and incubation for 1 hour, the canal contents were analyzed for the number of viable test bacteria and compared with that of inoculated teeth not treated with test agents. All test agents exhibited antimicrobial activity against all bacteria, with percent reductions in viable bacteria ranging from 64.3% to 100%. The combined data for Pulpdent paste and calcium hydroxide showed significantly higher antimicrobial activity than the combined data for camphorated paramonochlorophenol and formocresol for S. mutans and B. gingivalis or B. fragilis but showed no difference for A. viscosus.

Actinomyces↗
PubMed1991

Radiographic interpretation of endodontic file length.

The purpose of this study was to evaluate the accuracy of examiners when asked to make file length adjustments with only a radiograph. The examiners viewed several radiographs under proper viewing conditions but without the aid of measuring devices. Two files of varying lengths (sizes 10 and 15) were placed in maxillary and mandibular premolars and molars from cadavers. The nine examiners were 67.91% in agreement of actual file length adjustment needed when adjustments of up to 0.5 mm were needed, 17.76% when adjustments of from 0.5 up to 1.0 mm were needed, and 14.33% when adjustments of greater than 1.0 mm were needed.

Dental Pulp Cavity↗
PubMed1991

Human saliva coronal microleakage in obturated root canals: an in vitro study.

This study assessed salivary penetration through obturated root canals as related to time by using two methods of analysis--histological examination and dye penetrations. A total of 160 human maxillary anterior teeth were instrumented to size 60 Hedstrom file. Ten of the teeth were not obturated; 150 teeth were obturated by lateral condensation of gutta-percha and Roth's root canal sealer. Fifty of these teeth received intermediate restorative material temporaries to a thickness of approximately 3 mm. All teeth were immersed in 50 ml of whole human saliva and kept at 37 degrees C and 100% humidity. The saliva was changed daily. At 2, 7, 14, 28, and 90 days, 32 teeth were removed from the saliva. Of these, two were unobturated and were examined for bacterial penetration by culturing of the apical one-third. Ten teeth without temporaries were immersed in Pelikan ink for 2 days to demonstrate the extent of salivary penetration. These teeth were decalcified and cleared to allow direct measurement of dye penetration. Decalcified serial 7-microns-thick sections were prepared from the remaining 20 teeth, 10 with and 10 without intermediate restorative material temporaries. The sections were stained with hematoxylin and eosin stain and Brown and Hopps stain. Saliva penetration assessed in histological sections was significantly less than was visualized with dye analysis. Salivary penetration at 3 months was significantly greater than at the four earlier study periods. This amount of salivary penetration was considered to be clinically significant. The results strongly suggest retreatment of obturated root canals that have been exposed to the oral cavity for at least 3 months.

Analysis of Variance↗
PubMed1991

An analysis of success and failure of apicoectomies.

The radiographs from 715 patient charts were analyzed to study the effect of 11 factors on the success and failure of apicoectomies. Of these, 424 had recall radiographs of 6 months or more and were evaluated for changes in radiolucencies. The data were analyzed by cross-tabulation and chi-square analysis for significant relationships. Complete healing was found in 65% of the recall cases, while incomplete and unsatisfactory healing occurred in 29.4% and 5.6% of the cases, respectively. Complete healing was found to increase with patient age. Those over 60 yr of age had the highest percentage of complete healing. No statistical difference in healing was found between maxillary and mandibular teeth. Also, postsurgical healing associated with those teeth which were inadequately obturated with gutta-percha, silver points, or paste-filling materials did not differ significantly. No significant difference in healing was found between the teeth that were retreated nonsurgically before surgery and those that were not. Healing was independent of the placement of a retrofilling as well as the type of retrofilling period. Significantly better healing was seen with teeth that were permanently restored following surgery.

Adolescent↗
PubMed1991

A clinical evaluation of the Endocater--an electronic apex locator.

The purpose of this study was to evaluate the accuracy of an electronic apex locator, the Endocater, in determining the location of the apical constriction or cementodentinal junction (CDJ). Measurements made by the Endocater were also compared with the adjustments recommended by an experienced endodontist. A total of 69 teeth with 99 canals from nine patients were evaluated. The results indicated that the evaluator was 95.8% and the Endocater 67.7% accurate in positioning the probe within +/- 1.000 mm from the CDJ. Thirty-three canals or 34.4% appeared to be clinically acceptable radiographically and no adjustments were deemed necessary by the evaluator. There was a significant difference (p less than 0.003) between the evaluator's ability to adjust the electronically generated file length radiograph to acceptable clinical standards and the Endocater's ability to determine the location of the CDJ. A total of 59 canals (59.6%) of the electronically determined working lengths were beyond the CDJ (n = 99). In 27 canals, the tip of the probe was greater than 1 mm beyond the constriction. Without radiographs to confirm working lengths, many canals in this study would have been overinstrumented. Future research with electronic apex locators is needed before accepting the technique as a substitution for radiographic working length determination.

Dental Pulp Cavity↗
PubMed1991

Antiarrhythmic activity of amiloride: mechanisms.

We have previously shown that amiloride suppresses the induction of sustained ventricular tachycardia both in dogs late following myocardial infarction and in patients. In those studies the only electrophysiologic correlate of amiloride's antiarrhythmic activity observed was prolongation of ventricular effective refractory period at the zone bordering the infarct. The purpose of this study was to assess the pharmacologic effects of amiloride associated with antiarrhythmic efficacy. However, amiloride has multiple pharmacologic effects, including inhibition of the slow inward calcium current (ICa), inhibition of the sodium-calcium and sodium-hydronium ion exchangers, acidification of intracellular pH resulting in partial inhibition of the inwardly rectifying potassium current (IK1), and increase in serum potassium and magnesium. The approach used in this study was to use selective pharmacologic probes to produce the known components of amiloride's pharmacologic effects. The selective agents consisted of verapamil (partial blockade of ICa), 3',4'-dichlorobenzamil (partial inhibition of the Na-Ca exchanger), 5-(N-ethyl-N-isopropyl) amiloride (partial inhibition of the Na-H exchanger), the combination of these congeners, KCl infusions to increase serum potassium, MgSO4 infusions to increase serum magnesium, the combination of KCl and MgSO4 infusions, barium (partial block of IK1), ryanodine (partial blockade of sarcoplasmic reticulum calcium release), and placebo. In this study only barium produced antiarrhythmic and electrophysiologic effects similar to those of amiloride. However, amiloride prolongs border zone refractoriness selectively, whereas barium prolongs refractoriness diffusely throughout the myocardium. Blockade of ICa by verapamil, increases in serum magnesium and potassium alone or in combination, and partial blockade of sarcoplasmic reticulum by ryanodine were not antiarrhythmic in this model. Monotherapies that produced partial blockade of the Na-Ca and Na-H exchangers separately did not produce antiarrhythmic activity. However, the combination of these amiloride congeners reproduced the antiarrhythmic activity of amiloride but did not prolong border zone refractoriness. From these studies we conclude that the antiarrhythmic activity of amiloride relates to (a) selective blockade of IK1 in the border zone and/or (b) combined inhibition of sodium-calcium and sodium-hydronium ion exchangers.

Amiloride↗
PubMed1991

CT appearance of the pelvis after cesarean section.

Myometrial defects at the incision site after cesarean section may appear bizarre on CT scans, especially in the case of low transverse incisions, but may not indicate clinically significant dehiscence. These CT findings should be regarded as common in the patient without complications after cesarean section, so that unnecessary surgical intervention and additional treatment can be avoided.

Cesarean Section↗
PubMed1991

Computed tomography for evaluation of puerperal infections.

Pelvic computed tomography was used to evaluate 74 women with persistent puerperal infection. There was at least one abnormal roentgenographic finding in 57, and these are correlated with clinical and surgical findings. In 16 women, a palpable pelvic mass was seen on tomography, however, masses not appreciated clinically were visualized in another 29 women, and in five, a clinically palpable mass was not visualized by tomography. In 12 women who had a normal pelvic examination, septic pelvic thrombophlebitis was diagnosed by tomography. Over-all, there was poor correlation with roentgenographic findings and uterine incisional necrosis and dehiscence. We conclude that pelvic tomography is useful to evaluate some women with persistent puerperal infection, but that these studies must be correlated with clinical findings.

Adolescent↗
PubMed1990

Low-dose aspirin. II. Relationship of angiotensin II pressor responses, circulating eicosanoids, and pregnancy outcome.

Forty pregnant women (28 to 32 weeks' gestation) were given low-dose aspirin therapy (81 mg/day) from the time of enrollment until delivery; circulating eicosanoid levels and angiotensin II pressor responses were measured before and after 1 week of aspirin therapy. Subsequent clinical outcome was correlated with these results. All women had significant reductions in serum and plasma thromboxane B2 levels with aspirin treatment (p less than 0.01). Eleven women who remained sensitive to the pressor effects of angiotensin II (effective pressor dose less than 10 ng/kg/min) after 1 week of low-dose aspirin treatment exhibited significant decreases (p less than 0.05) in plasma 6-keto-prostaglandin F1 alpha (264 +/- 119 vs 161 +/- 31 pg/ml, mean +/- SD) and prostaglandin E2 (476 +/- 174 vs 351 +/- 112 pg/ml) levels. In contrast, patients who were either nonsensitive (refractory) to angiotensin II (n = 18; greater than or equal to 10 ng/kg/min) before aspirin or became nonsensitive after aspirin administration (n = 11) had no change in either plasma 6-keto-prostaglandin F1 alpha or prostaglandin E2 concentrations. The occurrence of pregnancy-induced hypertension was 100% in the women who remained angiotensin II sensitive during aspirin therapy as compared with 36% and 39% in the other two groups (x2 = 16.14; p less than 0.001). Thus during low-dose aspirin therapy a failure to develop refractoriness to infused angiotensin II is associated with a nonselective inhibition of eicosanoids and the almost certain development of pregnancy-induced hypertension. These observations may reflect a basic defect in vascular adaptation to pregnancy.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Placental transfer of cefazolin and piperacillin in pregnancies remote from term complicated by Rh isoimmunization.

Although the administration of prophylactic antibodies for intrauterine transfusion is controversial, little information is available regarding placental transfer of antibiotics administered to the mother, or whether the presence of hydrops affects this placental transfer. Sixteen intravascular intrauterine transfusions were performed in 10 patients. Seven (10 procedures) patients were given 2 gm of cefazolin before the procedure and samples were obtained by fetal vascular access. Three patients (six procedures) were given 4 gm of piperacillin and samples were similarly obtained. Specimens were obtained for fetal serum, maternal serum, and amniotic fluid antibiotic concentration. The mean serum cefazolin concentration in hydropic fetuses was 18.04 +/- 3.37 micrograms/ml, and in nonhydropic fetuses the concentration was 21.02 +/- 17.8 micrograms/ml (p = 0.72). The mean fetal serum concentration of piperacillin was 22 +/- 12 micrograms/ml. The placental transfer of both drugs was similar. We conclude that the transplacental passage of these antibiotics is prompt and that the presence of hydrops does not significantly impair the passage of cefazolin.

Blood Transfusion, Intrauterine↗
PubMed1990

Nomograms for rapid estimation of intravascular intrauterine exchange transfusion.

Fetal exchange transfusion is complicated by the fact that vascular access must be maintained while the number of exchanges needed to achieve a desired post-transfusion hematocrit is calculated. A rapid method for estimating the number of exchange transfusions would greatly simplify fetal exchange transfusion for blood group isoimmunization. In this report, we present a graphic method for determining the number of exchange transfusions necessary to achieve a post-transfusion hematocrit of 45%, using a nomogram for 5- and 10-mL exchange transfusion volumes.

Blood Transfusion, Intrauterine↗
PubMed1989

The effects of steam sterilization and usage on cutting efficiency of endodontic instruments.

The effects of steam sterilization and usage on sharpness were evaluated on #25 endodontic files. Files were used to instrument 1, 5, and 10 molars. Control groups determined the effect of steam sterilization alone on cutting efficiency of unused files. A cutting efficiency test was performed on an apparatus that compares sharpness of files when used in linear motion. Scanning electron microscopic analysis was performed in each group. Significant differences were found between experimental files used to instrument 1 molar and those used for 5 or 10 molars. The difference in cutting efficiency between the second and third experimental groups was not significant, indicating that most of the decrease in sharpness occurred with use between one and five molars. No significant difference was found between the control groups, indicating no decrease in cutting efficiency by sterilization alone. The scanning electron microscopic analysis supported the statistical data.

Dental Instruments↗
PubMed1989

A statistical analysis of surgical and nonsurgical endodontic retreatment cases.

A total of 1300 endodontic patient charts were analyzed for factors that may have contributed to the failure of the original treatment or the success of the retreatment. Of those surveyed, 667 had recall information of 6 months or more and were used to consider success rates. The remaining cases were analyzed for other information. The findings were tabulated and analyzed by computer for significant relationships. The overall success rate for retreatment was 65.6% with an additional category of "uncertain" of 18.3%. Surgical treatment was necessary to retreat 53.5% of the cases.

Adolescent↗
PubMed1989

Cardiac arrhythmias during pregnancy.

Arrhythmias of the pregnant patient are rare. In most cases, the therapeutic agent chosen should be much the same as that in the nonpregnant patient, and an understanding of the pharmacology of the antiarrhythmic agents is necessary for rational use in the pregnant patient with an arrhythmia. Substantial experience has been accumulated using some of the older agents for treatment of arrhythmias in pregnancy. As newer agents become available, there may be indications for their use in pregnancy; however, we recommend initially using well-known drugs until more experience is gained with the newer ones. The choice of an agent should be made only after thorough evaluation of the patient's symptoms, accurate diagnosis and an analysis of potential benefit versus potential risk to the mother or fetus.

Anti-Arrhythmia Agents↗
PubMed1989

Prevalence of lumbosacral intervertebral disk abnormalities on MR images in pregnant and asymptomatic nonpregnant women.

The prevalence of lumbosacral intervertebral disk bulge and herniation on sagittal magnetic resonance (MR) images was determined in 45 pregnant subjects and 41 asymptomatic nonpregnant women of childbearing age. MR technique differed for the pregnant and nonpregnant groups. Fifty-three percent of pregnant and 54% of nonpregnant women had an abnormal disk (bulge or herniation) at one or more levels (L3-4, L4-5, or L5-S1). The difference was not statistically significant. There was also no significant difference in the distribution of outcomes among the 45 pregnant subjects, 17 parous nonpregnant women, and 24 nulliparous women. The results suggest that lumbosacral disk bulges or herniations are common in women of childbearing age, whether pregnant or not, and that, contrary to an earlier report, pregnant women do not have an increased prevalence of disk abnormalities.

Adult↗