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Biomedical subjects

J J Smith

Publications and source records attributed to J J Smith.

At least 19 recordsLinked to original sources
PubMed1992

Distal colonic hyperplastic polyps do not predict proximal adenomas in asymptomatic average-risk subjects.

The significance of distal colonic hyperplastic polyps was investigated in 482 asymptomatic average-risk subjects, aged 50-75 years, in whom fecal occult blood test results were negative and who underwent screening colonoscopy. The incidence of adenomas in the colon proximal to the sigmoid-descending colon junction in subjects with hyperplastic polyps distal to that point was 18% and was similar to the incidence of proximal colonic adenomas in subjects with no distal colonic polyps (15%). The incidence of proximal colonic adenomas in subjects with no distal colonic adenomas was 38% and was significantly greater than the incidence found in individuals with no distal colonic polyps or only hyperplastic polyps. Our data do not support distal colonic hyperplastic polyps as markers for proximal colonic adenomas in asymptomatic average-risk subjects.

Adenoma↗
PubMed1992

Cervical canal leakage after internal bleaching.

The effects that walking bleach procedures had on root canal filling leakage and the extent of dentinal penetration were studied. Forty teeth were divided into four groups: 1--GP, set sealer, no base; 2--GP, set sealer, 2-mm Cavit base; 3--GP, unset sealer, no base; and 4--GP, unset sealer, 2-mm Cavit base. All were bleached for 7 days, fresh bleach was added for another 7 days, then methylene blue dye was placed for 5 days. The extent of dye penetration apically along the root canal filling and through the dentinal tubules was evaluated. The results indicate that 2 mm of Cavit was sufficient to significantly reduce linear leakage and dentinal penetration. The Cavit should be placed to a level slightly coronal to the facial cementoenamel junction. Teeth with cemental defects demonstrated greater perpendicular dye penetration in the areas of the defects than those with intact cementum. The data from this study suggest the use of a base material over gutta-percha in clinical practice prior to internal walking bleach procedures.

Analysis of Variance↗
PubMed1992

A comparison of apical seal: chloroform versus halothane-dipped gutta-percha cones.

A dye penetration study was done to compare apical leakage among three groups of extracted teeth obturated with a lateral condensation technique. In one group the master gutta-percha cones were customized in the apical portion of the canals after being dipped in chloroform. A second group used halothane as the customizing agent. No dip was used in the third group, and all three were then laterally condensed. The teeth were cleared and dye penetration was measured. Statistical analysis using a Kruskal-Wallis one-way analysis of variance of the data showed no significant difference among the groups at the p < 0.05 level.

Analysis of Variance↗
PubMed1992

Randomized comparison of cisplatin plus epirubicin or doxorubicin for advanced epithelial ovarian carcinoma. A multicenter trial.

Stage III and IV epithelial ovarian cancer patients were prospectively randomized to receive eight courses of 60 mg/m2 of cisplatin plus either 75 mg/m2 of epirubicin (62 patients) or 60 mg/m2 of doxorubicin (54 patients). Clinical response rates for cisplatin/epirubicin of 42% [15% complete response (CR) and 27% partial response (PR)] and for cisplatin/doxorubicin of 55% (24% CR and 31% PR) were not statistically different (p = 0.14). The negative second look rate was 35% (10/29) for cisplatin/doxorubicin and 17% (5/30) for cisplatin/epirubicin (p = 0.12). The progression-free interval for cisplatin/epirubicin (13 months) was not statistically different (p = 0.09) from that for cisplatin/doxorubicin (19 months). The median survivals for cisplatin/epirubicin (756 days) and cisplatin/doxorubicin (739 days) were similar (p = 0.70). Cardiotoxicity was greater for the cisplatin/doxorubicin group (p = 0.0003). With similar survival and less cardiotoxicity, the cisplatin/epirubicin regimen had the more favorable therapeutic index.

Adolescent↗
PubMed1992

Effects of aging on baroreflex regulation of sympathetic activity in humans.

Arterial baroreflexes contribute importantly to blood pressure regulation through their influence on parasympathetic outflow to the sinus node and sympathetic outflow to the peripheral circulation. Baroreflex control of heart rate is known to be diminished in older individuals. Whether advancing age is associated with a parallel attenuation in baroreflex control of sympathetic outflow to the peripheral circulation has not been studied in humans. To provide such information, we made direct measurements of muscle sympathetic nerve activity (MSNA) in healthy males who ranged in age from 18 to 71 yr. The subjects were arbitrarily divided into three groups: younger (18-34 yr; n = 35), middle aged (35-50 yr; n = 15), and older (51-71 yr; n = 16). Although basal levels of MSNA were higher in older subjects than in younger and middle-aged subjects, the gains of baroreflex control of MSNA were the same in the older, middle-aged, and younger subjects (-4.6 +/- 0.6, -4.8 +/- 0.9, -5.1 +/- 0.5 U/mmHg, P greater than 0.10). In contrast, the gains of baroreflex control of cardiac intervals were attenuated in the older and middle-aged subjects compared with the younger subjects (9.8 +/- 1.2, 13.6 +/- 1.4, 21.7 +/- 1.3 ms/mmHg, P less than 0.05). Our data indicate that although the parasympathetic component of the arterial baroreflex becomes impaired with advancing age, the sympathetic component can be well maintained in healthy individuals even into the seventh decade.

Adolescent↗
PubMed1992

cAMP stimulates bicarbonate secretion across normal, but not cystic fibrosis airway epithelia.

Adenosine 3',5'-cyclic monophosphate stimulates chloride (Cl-) secretion across airway epithelia. To determine whether cAMP also stimulates HCO3- secretion, we studied cultured canine and human airway epithelial cells bathed in a HCO3-/CO2-buffered, Cl(-)-free solution. Addition of forskolin stimulated an increase in short-circuit current that was likely a result of bicarbonate secretion because it was inhibited by a HCO3(-)-free solution, by addition of the carbonic anhydrase inhibitor, acetazolamide, or by mucosal addition of the anion channel blocker, diphenylamine 2-carboxylate. The current was dependent on Na+ because it was inhibited by removal of Na+ from the submucosal bathing solution, by addition of the Na+ pump inhibitor, ouabain, or by addition of amiloride (1 mM) to the submucosal solution. An increase in cytosolic Ca2+ produced by addition of a Ca2+ ionophore also stimulated short-circuit current. These data suggest that cAMP and Ca2+ stimulate HCO3- secretion across airway epithelium, and suggest that HCO3- leaves the cell across the apical membrane via conductive pathways. These results may explain previous observations that the short-circuit current across airway epithelia was not entirely accounted for by the sum of Na+ absorption and Cl- secretion. The cAMP-induced secretory response was absent in cystic fibrosis (CF) airway epithelial cells, although Ca(2+)-stimulated secretion was intact. This result suggests that HCO3- exist at the apical membrane is through the Cl- channel that is defectively regulated in CF epithelia. These results suggest the possibility that a defect in HCO3- secretion may contribute to the pathophysiology of CF pulmonary disease.

Animals↗
PubMed1991

Physical mapping of the Esterase-6 locus of Drosophila melanogaster.

The Esterase-6 gene locus of Drosophila melanogaster although well-characterized, has not been definitely mapped by in situ hybridization. In this paper, a high resolution in situ hybridization protocol using an avidin/biotinylated-horseradish peroxidase/diaminobenzidine system was adopted to refine the physical map position of the Esterase-6 locus. Clarity of signal, detail of banding pattern and absence of background allowed the assignment of a 1.8 kb cDNA encoding Esterase-6 to three bands within subsections 69 A1-A3 on the left arm of polytene chromosome 3. These data refine earlier deletion mapping and low resolution in situ hybridization results, which assigned Esterase-6 to 69A1-A5. The potential use of this high resolution in situ hybridization technique in the analysis of the physical organization of the Esterase-6 gene duplication and surrounding region is discussed.

Animals↗
PubMed1991

Screening colonoscopy in asymptomatic average-risk persons with negative fecal occult blood tests.

Colonoscopy was performed on 210 asymptomatic average-risk persons, aged 50-75 years, who had negative fecal occult blood test results. Colonoscopy was complete to the cecum in 209 subjects. Fifty-three subjects (25%) had adenomas and two had cancer. All of the adenomas greater than or equal to 1 cm in size and both cancers occurred in subjects aged greater than or equal to 60 years. Fifty-one percent of subjects with adenomas and one with cancer had no neoplasms distal to the sigmoid-descending colon junction. One subject had a major postpolypectomy hemorrhage that stopped spontaneously. Screening colonoscopy, therefore, has a high yield for detection of neoplasms in asymptomatic average-risk persons aged greater than or equal to 60 years with negative fecal occult blood test results. The yield is low in persons aged 50-54 years and intermediate in persons aged 55-59 years.

Adenoma↗
PubMed1991

Posture and the circulation: the age effect.

The primary instigator of circulatory response to the upright posture is the rapid displacement of about 10% of blood volume from the thorax to the lower body. The resultant hemodynamic deficit induces postural intolerance, especially orthostatic hypotension, in elderly over 70 years of age and in some young subjects after exposure to weightlessness. In this review, our objectives have been: 1) to describe in the normal subject the hemodynamic consequences of the headup posture, as well as lower body negative pressure, the compensatory responses intended to cope with these stresses, and their mechanisms; 2) to outline the effect of age on the circulatory responses to these stresses; and (3) to analyze and compare the tests currently used to assess circulatory tolerance. Our ability to design effective countermeasures to orthostatic circulatory intolerance is severely handicapped by our inadequate knowledge of the basic hemodynamic events incident to normal and abnormal orthostatic tolerance. We believe that better understanding and standardization of the postural tests, better experimental design to include greater emphasis on inter and intra-individual variability, and wider application of currently available noninvasive circulatory techniques would greatly improve the prospects for success in this research area.

Adaptation, Physiological↗
PubMed1991

Quantitation of differential renal function with Tc-99m MDP.

This study was designed to evaluate the usefulness of the bone tracer Tc-99m MDP for quantitative assessment of relative renal function as compared with renal imaging radiotracers used for that purpose. Differential renal function, i.e., the percent contribution each kidney makes to global renal function, was determined prospectively in 15 consecutive patients using Tc-99m MDP and a renal radionuclide tracer, either Tc-99m DTPA or Tc-99m GHA. Differential function was computed in all cases from the early (1-3 minutes) renal uptake of the tracers by region-of-interest analysis of the computer-acquired data. There was a high correlation between values of differential function obtained with Tc-99m MDP and those obtained with Tc-99m DTPA or Tc-99m GHA (r = 0.98, P less than 0.0001). Qualitative assessment of the images revealed equivalent scintigraphic patterns in all patients. It is concluded that the early characteristics of renal handling of Tc-MDP are sufficiently similar to those of Tc-DTPA and Tc-GHA so that accurate estimates of differential renal function are possible with this agent, and that Tc-MDP-determined renal differential most likely reflects differential glomerular filtration rate.

Aged↗
PubMed1991

Barium enema use in Indiana.

All 118 hospital-based radiology departments in Indiana responded to a survey of barium enema (BE) use. The percentage of community hospitals in Indiana using barium enema, both single contrast (SCBE) and double contrast (DCBE) for various indications, was similar to that reported for major medical centers around the world. The use of SCBE and DCBE did not differ between small and large hospitals or between hospitals in small versus large communities. There was, however, wide variation among community hospitals in their overall use of either contrast technique. Barium enema usually was performed without antecedent sigmoidoscopy. However, 60% of Indiana hospitals perform BE on the same day as flexible sigmoidoscopy. The results indicate that the use of BE in community hospitals in Indiana is similar to that reported for major medical centers. Like major medical centers, there is no consensus regarding many issues in the performance of BE.

Barium Sulfate↗
PubMed1990

Multimodality treatment of complex renal calculi.

More than 2,500 patients were treated for urolithiasis from 1984 to 1987. In an effort to define the relative role of extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy with respect to size, location and composition of the calculus 912 of these patients (224 of whom underwent percutaneous nephrolithotomy and 688 of whom underwent extracorporeal shock wave lithotripsy) were reviewed. Size proved to be the only significant factor in the success and complication rates of extracorporeal shock wave lithotripsy but it did not affect the outcome of percutaneous nephrolithotomy. The roles of these 2 modalities were then examined with respect to the treatment of complex renal calculi. We reviewed 376 patients with complex renal calculi, including 40 percutaneous nephrolithotomy patients from the initial 912 patients studied. The initial therapy in 100 of these patients, treated consecutively, was extracorporeal shock wave lithotripsy. The remaining 276 patients were treated by percutaneous nephrolithotomy. The success rate of extracorporeal shock wave lithotripsy monotherapy in the treatment of complex renal calculi was 36%. The success rate of primary percutaneous nephrolithotomy was 83%. We conclude that percutaneous nephrolithotomy should be the primary therapy for patients with complex renal calculi. Extracorporeal shock wave lithotripsy is the preferred treatment for patients with smaller calculi and as an adjunct to percutaneous nephrolithotomy.

Combined Modality Therapy↗
PubMed1990

Estimation of 24-hour thyroid uptake of I-131 sodium iodide using a 5-minute uptake of technetium-99m pertechnetate.

The authors have developed a method to estimate the 24-hour sodium iodide thyroid uptake based on a 5-minute Tc-99m pertechnetate thyroid uptake using the equation: Estimated Iodide Uptake = 17.72*In(Pertechnetate Uptake) + 30.40. This estimation has a correlation coefficient of 0.90. It is based on a data pool of 44 patients who underwent I-131 and Tc-99m studies within 2 weeks of each other from 1978-1988, with established diagnoses as follows: 12 euthyroid, 6 hyperthyroid with multinodular goiters, 15 hyperthyroid with diffuse goiters, 4 with subacute thyroiditis, and 7 unknown. The population consisted of 30 women and 14 men with a mean age of 52.0 +/- 17.5 years; this sample was screened for use of thyroid hormone, propylthiouracil, and radiographic contrast. The authors believe this estimation method is of value whenever a 24-hour iodide uptake is desired, and where speed and minimizing radiation dose are factors. This method is strongly recommended for thyroid uptake evaluation before I-131 therapy.

Adolescent↗
PubMed1990

Bradykinin stimulates airway epithelial Cl- secretion via two second messenger pathways.

In canine airway epithelial cells, bradykinin increases intracellular concentrations of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], cytosolic calcium concentration ([Ca2+]c), and adenosine 3',5'-cyclic monophosphate (cAMP). To determine the role of these second messengers in bradykinin-stimulated Cl- secretion, we studied the secretory response to this peptide using canine tracheal monolayers mounted in Ussing chambers. Bradykinin stimulated Cl- secretion [measured as short-circuit current (Isc)] when added to submucosal or mucosal surfaces; however, secretory responses differed substantially. Submucosal addition of bradykinin induced a biphasic increase in secretion; mucosal addition induced a monophasic increase in secretion. Both responses were mediated by B2 receptors. We show that activation of bradykinin receptors can stimulate Cl- secretion in two ways. 1) Bradykinin added to either surface stimulates prostaglandin synthesis and release at the basolateral surface. This leads to activation of prostaglandin E2-sensitive receptors on the basolateral surface that are coupled to cAMP production and an increase in apical membrane Cl- conductance. 2) In addition, bradykinin added to the submucosal surface increases Ins(1,4,5)P3 and [Ca2+]c levels, which enhance basolateral K+ conductance and the electrical driving force for apical Cl- exit. Whereas secretion requires activation of apical Cl- channels, the data show that Cl- secretion can also be modulated by activation of basolateral K+ channels. These data indicate that bradykinin-induced transepithelial Cl- secretion is mediated by two independent, second messenger pathways. These results provide the first evidence for expression of both pathways in a polar fashion in an epithelial monolayer.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Balloon dilatation of the prostate.

It is important to be objective in selecting candidates for this procedure and in evaluating their outcome. The size of the prostate does not seem to be relevant. Alpha blockers and balloons still produce unpredictable results, and neither alternative duplicates the results of transurethral resection. If, however, the patient is not in serious voiding trouble and is willing to exercise genuine patience, one approach could be a blocker if he has early symptoms and is not in trouble; otherwise, use the balloon. When either or both fail, TURP is required if the patient's condition permits, for TURP remains the standard. Objective assessment with an open mind is essential. Balloon dilatation is a safe, simple, but unpredictable alternative to transurethral resection. It may be done on an ambulatory basis, although it requires anesthesia, and has led to neither impotence or incontinence. It may be performed on the limited-risk patient. It has succeeded in two thirds of patients in retention or who did not respond to alpha blockers. Nonetheless, objective measures of success rarely duplicate those regularly achieved by TURP.

Aged↗