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Biomedical subjects

C E Brown

Publications and source records attributed to C E Brown.

At least 55 records · Page 3Linked to original sources
PubMed1996

PAN3 encodes a subunit of the Pab1p-dependent poly(A) nuclease in Saccharomyces cerevisiae.

The Pab1p-dependent poly(A) nuclease (PAN) from Saccharomyces cerevisiae copurifies with polypeptides of approximately 127 and 76 kDa. Previously, it was demonstrated that the 127-kDa Pan2 protein is required for PAN activity (R. Boeck, S. Tarun, M. Reiger, J. Deardorff, S. Müller-Auer, and A.B. Sachs, J. Biol. Chem. 271:432-438, 1996). Here we demonstrate that the 76-kDa protein, encoded by the nonessential PAN3 gene, is also required for enzymatic activity. Deletion of PAN3 resulted in the loss of PAN activity in yeast extracts, and immunodepletion of Pan3p from purified PAN fractions abolished enzymatic activity. We show by coimmunoprecipitation and directed two-hybrid studies that the Pan2 and Pan3 proteins physically interact. In addition, we demonstrate that a deletion of PAN2, PAN3, or both resulted in similar increases in mRNA poly(A) tail lengths in vivo. These data strongly suggest that both Pan2p and Pan3p are required subunits of the PAN enzyme and that PAN functions in vivo to shorten mRNA poly(A) tails.

Amino Acid Sequence↗
PubMed1995

Management of a radial fracture in an adult bull.

An 823-kg 4-year-old Holstein bull was examined because of acute lameness of the left forelimb. Radiography revealed a closed, comminuted, spiral fracture of the radius that extended from the distal portion of the diaphysis to the antebrachiocarpal joint. The fracture was repaired with combination of internal fixation (2 compression plates, 1 of which incorporated a condylar screw and both of which were luted) and external coaptation (full-limb cast and Thomas-Schroeder splint). The development of larger implants and the combination of internal and external fixation methods provides hope that certain fractures in cattle that were once thought irreparable can now be treated.

Animals↗
PubMed1995

Serotonin-induced paw edema in the rat: pharmacological profile.

1. Serotonin (5-HT) induced a linear increase in paw weight in rats within 1 hr of an intraplantar injection (50 microliters vol) over a concentration range of 0.005-0.2 mg/ml. At the 0.2 mg/ml concentration, a 16-fold increase in paw weight was observed as compared to saline-injected controls. 2. Serotonin antagonists, such as LY53857, were the most effective antagonists of 5-HT induced paw swelling, producing near complete antagonism and an approximate ED50 of 0.1 mg/kg. A mixed 5-HT/histamine antagonist, cyproheptadine, also produced a nearly complete inhibition of the 5-HT response with an approximate ED50 of 1.3 mg/kg. 3. Dopamine agonists (pergolide, quinpirole), yohimbine, dexamethasone and nifedipine also produced a significant degree of antagonism of the 5-HT response. 4. Clonidine, prazocin, chlorpheniramine, cimetidine, various dopamine antagonists, imipramine, cyclosporine A, piroxicam and superoxide dismutase were all ineffective at altering the paw swelling response to 5-HT.

Adrenergic Agonists↗
PubMed1995

Unusual fracture of a maxillary second premolar.

Root fractures of posterior teeth are rare and occur as a result of severe trauma. This study describes a horizontal root fracture of a maxillary second premolar discovered during routine full-mouth radiographic examination. The tooth was asymptomatic and responded positively to electric pulp testing. The patient had no recollection of a causative event nor was there physical evidence of previous trauma. It is speculated that the fracture was caused when overzealous force was used in seating an overcontoured complete gold crown restoration of an adjacent tooth.

Aged↗
PubMed1995

An in vitro study of apical extrusion of sodium hypochlorite during endodontic canal preparation.

One hundred fifty-three single rooted teeth were divided into four groups. Canals were cleaned and shaped using the balanced forces technique. In one group of 50 teeth, irrigation was delivered with the irrigation needle deep within the root canal. In the other group of 51 teeth, the needle was placed passively in the coronal access cavity and the irrigation carried into the root canal during filing. The remaining 52 teeth in the control groups were treated in the same manner using distilled water as the irrigation solution. The concentration of sodium extruded apically was measured by means of atomic emission spectrophotometry, and the volume of sodium hypochlorite extruded was calculated. Significantly more sodium hypochlorite was extruded apically during deep delivery of the irrigation (p<0.05). It is concluded that the use of a reservoir of irrigation in the coronal access cavity results in significantly less apical extrusion of irrigation solution than with deep delivery.

Analysis of Variance↗
PubMed1994

Effect of root canal treatments on dentin permeability.

Calcium hydroxide has been used to slow or reverse external root resorption subsequent to trauma. In this study, an experimental model was established to study the diffusion of calcium ions from the canal to the root periphery after various intracanal treatments. Analyses of calcium ion concentrations from extraradicular samples revealed that dentin specimens varied in their rates of diffusion of calcium and that treatment of the canals with various agents affected the amounts of calcium recovered.

Analysis of Variance↗
PubMed1994

Interpretation of periapical lesions using RadioVisioGraphy.

Density and gray-scale changes in radiographs are important visual features the clinician uses to evaluate changes in bone pattern. With the advent of a new direct digital radiology system, RadioVisioGraphy (RVG), the controlled adjustment of contrast is now possible. The purpose of this study was to compare RVG's diagnostic potential for detecting periapical lesions with that of conventional radiography. Lesions were created in human cadaver specimens and radiographed conventionally and with RVG. Images were evaluated by three endodontists. Results were: (a) when no lesion existed, conventional radiographs were more diagnostic than RVG at a significance level at p < or = 0.05; (b) when lesions were enlarged to involve lamina dura and medullary bone, RVG was superior at p < or = 0.05; and (c) no difference was found between conventional radiography and RVG when the lesion involved cortical bone.

Alveolar Bone Loss↗
PubMed1994

Interpretation of endodontic file lengths using RadioVisiography.

The purpose of this investigation was to compare RadioVisioGraphy (RVG) imaging with conventional radiography in determining endodontic file length adjustment. Human cadaver sections with first or second molars were used. Files were inserted into canals at randomly selected lengths, from 4 mm short of the radiographic apex to 3 mm beyond. Radiographs and RVG images were evaluated to determine the adjustment needed to place the file 0.5 mm from the radiographic apex. Results showed no significant difference in the ability of endodontists to make accurate file length adjustments using conventional radiography versus RVG. In this study, it was found that: (a) accurate file length adjustments can be made from an image two times larger than the actual tooth; (b) RVG is not significantly better than conventional radiography; and (c) if both methods are available, RVG is preferred because of the significant reduction in radiation dose.

Analysis of Variance↗
PubMed1994

Evaluation of an apatite cement as a root end filling material.

A self-setting apatite cement, EBA cement, and amalgam with varnish were tested for root end sealing ability using a fluid filtration and dye technique. Single-rooted human teeth were prepared in vitro to receive root end fillings. Experimental groups were amalgam with two layers of varnish, EBA cement with dry cavity, EBA cement within a wet cavity, apatite cement within a dry cavity, and apatite cement within a wet cavity. Fluid filtration measurements were made at 6, 24, and 7 days, and 1 and 3 months. Each specimen was also subjected to a dye leakage test using Procion Green dye at 3 months. Results indicated that apatite cement provided a comparable seal to amalgam and EBA cement. This finding, in conjunction with its excellent biocompatibility, suggests that apatite cement is an acceptable alternative to present-day root end filling materials.

Aluminum Oxide↗
PubMed1994

Effects of antiviral nucleoside analogs on human DNA polymerases and mitochondrial DNA synthesis.

Inhibition constants were determined for 16 nucleoside analog triphosphates against human DNA polymerases alpha, beta, gamma, and epsilon, and 7 nucleoside analogs were examined as inhibitors of mitochondrial DNA synthesis in human Molt-4 cells in culture. The results demonstrate no clear quantitative or qualitative correlation between inhibition of DNA polymerases, particularly mitochondrial DNA polymerase gamma, and the inhibition of mitochondrial DNA synthesis in Molt-4 cell culture. Furthermore, the data indicate that inhibition of isolated DNA polymerases may not be predictive of in vitro or in vivo toxicity. Finally, it is not clear whether inhibition of mitochondrial DNA synthesis will be an accurate predictor of the potential in vivo toxicity of antiviral nucleoside analogs.

Antiviral Agents↗
PubMed1994

The economic advantages of measured change in health care: an example from obstetrics.

To evaluate the economic effects of an increased oxytocin dosage for labor stimulation at a large urban hospital, a cost analysis of a before and after cohort, analytic clinical trial was performed. Delivery outcomes for two different oxytocin dosages were evaluated from the perspective of provider and consumer costs attributable to the oxytocin regimen. The high-dose oxytocin regimen resulted in an estimated provider and consumer cost savings of approximately $350,000 per year. We conclude that a small change in health care, such as an increased infusion rate of a single drug, can have economic advantages.

Cost Savings↗
PubMed1993

Antepartum prediction of pulmonary hypoplasia: an elusive goal?

Diagnosis of fetal pulmonary hypoplasia could be of great benefit to the obstetrician in the management of those pregnancies complicated by prolonged preterm ruptured membranes. Ultrasonography and magnetic resonance imaging were employed for fetal diagnosis of pulmonary hypoplasia and we were unable to predict accurately those fetuses with pulmonary hypoplasia using two different published ultrasound formulas. Moreover, magnetic resonance imaging appears not to offer any advantages over sonographic evaluation in the diagnosis of fetal pulmonary hypoplasia.

Adult↗
PubMed1993

Endothelin levels in human amniotic fluid at mid-trimester and at term before and during spontaneous labor.

Endothelin (ET)-1 is synthesized in human amnion and immunoreactive (ir) ET is present in amniotic fluid in concentrations 10- to 100-times those found in plasma. ET-1 is a potent uterotonin; therefore, the possibility must be considered that ET-1, derived from amnion/amniotic fluid, serves to promote the uterine contractions of human labor. In term pregnancies, after labor begins, the amniotic fluid normally becomes divided into the upper and forebag compartments as the fetal presenting part is engaged in the maternal pelvis. The forebag tissues are exposed in the vagina because of cervical dilatation. Vaginal fluid contains microorganisms, bacterial toxins, and cytokines, e.g., interleukin-1 beta, that oblige an inflammatory reaction. Increased ET-1 formation in these tissues of the forebag would be indicative that the greater rate of ET-1 formation and entry into amniotic fluid was an aftereffect of labor, not a cause of parturition. The levels of irET in amniotic fluid during the midtrimester of human pregnancy, 93.3 +/- 7.4 pmol/L (mean +/- SEM, n = 38), were significantly greater than those in amniotic fluid at term before the onset of labor, 39.8 +/- 4.1 (n = 33, p < 0.01). The levels of irET in the upper compartment during labor, 45.5 +/- 3.5 pmol/L (n = 40), were not significantly different from those in amniotic fluid before labor, but were significantly less (p < 0.01) than those in amniotic fluid of the forebag, 82.1 +/- 5.2 pmol/L (n = 125). These findings are suggestive that increases in the concentration of ET in amniotic fluid at parturition are confined to the forebag and are the result of ET formation after labor begins. Inflammation of the tissues lining the forebag compartment of the amniotic fluid is a normal consequence of labor. Therefore, the entry of inflammatory response mediators, some of which are uterotonins, viz., ET and prostaglandins, into forebag amniotic fluid is an aftereffect of labor and not indicative of a role for these agents (in amniotic fluid) in the initiation of parturition. In a subset of the amniotic fluids from normal pregnancies at term, prostaglandin (PG) levels also were determined. There was a highly significant correlation between the levels of irET and PGE2 in the forebag compartment (p < 0.0001); there was no correlation between irET and PGE2 levels in the upper compartment or in amniotic fluid collected at term prior to labor onset.(ABSTRACT TRUNCATED AT 400 WORDS)

Amniotic Fluid↗
PubMed1993

The pelvis after cesarean section and vaginal delivery: normal MR findings.

OBJECTIVE: In postpartum women, pain and fever can indicate serious complications, such as phlegmon or abscess of the parametrium or bladder flap, ovarian vein thrombosis, or uterine dehiscence. The purpose of this study was to ascertain the MR appearance of the normal pelvis after uncomplicated cesarean section and vaginal delivery. SUBJECTS AND METHODS: Twenty-two patients (14 who had cesarean sections and eight who had vaginal deliveries) were imaged with a superconducting 0.35-T MR system 1-5 days after delivery. Sagittal and axial T1-weighted, proton density-weighted, and T2-weighted spin-echo images were acquired. Phase reconstruction of the axial T1-weighted sagittal images was performed to confirm flow in the ovarian veins. The ovarian veins, parametrium, bladder flap, endometrium, and uterine incision were analyzed on all images. RESULTS: The uterine incision was well seen in all 14 patients who had cesarean section. The signal characteristics of the incision suggested subacute hematoma within the myometrium, and no myometrial defects were seen. In all 13 patients with a low transverse incision, a hematoma of the bladder flap was seen. Patency was confirmed in the majority of ovarian veins (39/44). No evidence of parametrial edema or mass, which can be seen in abscess or phlegmon, was found in any of the 22 patients. The ovarian perivenous fat did not show edema, which can indicate acute ovarian vein thrombosis. Increased signal in the endometrial cavity was seen in all patients; the signal characteristics were similar to those of subacute hematoma, consistent with clinical findings. CONCLUSION: Normal findings of the postpartum pelvis on MR imaging are subacute hematoma in the uterine incision, bladder flap, and endometrial cavity. Patent ovarian veins are demonstrated in most (89%) cases.

Adult↗
PubMed1993

Extracorporeal shock wave lithotripsy treatment of lower caliceal stones: an update on the use of a cobra catheter for direct irrigation.

As the general experience with extracorporeal shock wave lithotripsy (ESWL) for renal calculi broadens, it is increasingly evident that the clearance of stone fragments in lower pole calices needs to be improved. The stone-free rate posttreatment for lower caliceal stones is consistently less than that for other upper tract locations. Utilization of a cystoscopically placed cobra catheter for directed irrigation during ESWL with a Dornier HM4 lithotripter resulted in an increase of our lower caliceal stone-free rate to 64% (29/45) at 1 month follow-up and 73% (33/45) at 3 months follow-up compared to 36% (15/42) of randomly selected controls at 1 month (p less than 0.007) and 54% (23/42) at 3 months (p < 0.070). Patients were included in the study if they had a solitary calculus, less than 2 cm in size, located in a normal lower pole calix and had no indwelling stent placed by the referring physician. The cobra catheter was positioned in the appropriate calix with fluoroscopic guidance under intravenous sedation. Statistical analysis was performed using Pearson's Chi-square test. We conclude that the pre-ESWL treatment placement of a cobra catheter into the lower pole calix and intermittent irrigation during the procedure is a useful adjunct in the successful treatment of lower caliceal calculi.

Endoscopy↗
PubMed1992

An evaluation of 646 stone patients treated on the HM4 extracorporeal shock wave lithotriptor.

Extracorporeal shock wave lithotripsy (ESWL) has become the preferred treatment modality for the majority of urinary tract calculi. This form of treatment boasts excellent patient acceptance and has significantly reduced the need for surgical intervention. An evaluation of our first 646 patients undergoing 722 ESWL treatments at Walter Reed Army Medical Center revealed an overall stone-free rate at 1 and 3 months of 52% and 79%, respectively. The exact location of each stone within the kidney and ureter further determined the stone-free rates at 1 and 3 months. Stone-free rates at 3 months ranged from 89% for renal pelvic stones to 64% for lower pole caliceal stones. Upper third ureteral stones treated in situ without stenting resulted in a 74% stone-free rate at 3 months. This rate increased to 85% when these patients were stented and treated in situ. Although statistically insignificant, when the upper third ureteral stones were manipulated into and treated in the renal pelvis (31% of our patient population) the 3-month stone-free rate increased to 87%. Attempts were made to stent all ureteral stones before treatment. The stone-free rate at 3 months was 86% for mid third ureteral stones and 81% for lower third ureteral stones. The overall retreatment rate was 11.8% with a complication rate of 7.6% and a 6.3% post-ESWL intervention rate (open or percutaneous surgery, stent or percutaneous nephrostomy placement).

Equipment Design↗
PubMed1991

Renal pelvicalyceal dilation in antepartum pyelonephritis: ultrasonographic findings.

The purpose of the present study was to determine whether pregnant women with pyelonephritis have differences of pelvicalyceal systems, compared with normal pregnant control subjects, that might predispose to upper urinary tract infection. Ultrasonographic examination of both kidneys in coronal and axial planes of 24 women with clinical pyelonephritis and positive urine cultures was compared with results in control subjects matched for gestational age, parity, and race. Women with right or bilateral pyelonephritis had increased dilation of the right calyceal system, compared with controls (1.7 cm vs 0.8 cm, p less than 0.001). Renal pelvis volume was increased as well (29.3 vs 5.5 cm3, p less than 0.001). Renal pelvicalyceal dilation in antepartum pyelonephritis was significantly increased compared with normal physiologic dilation of pregnancy. Follow-up nephrosonography in a small number of women (N = 10) after treatment of pyelonephritis did not reveal a consistent decrease in renal dilation, suggesting that dilation of the renal pelvis may antedate pyelonephritis. Further study of this phenomenon is warranted.

Dilatation, Pathologic↗