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Biomedical subjects

J J Smith

Publications and source records attributed to J J Smith.

At least 163 records · Page 9Linked to original sources
PubMed1993

Ruminants express a prolactin receptor of M(r) 33,000-36,000 in the mammary gland throughout pregnancy and lactation.

Developmental variation in the expression of the prolactin receptor in the ruminant mammary gland was investigated. Affinity chromatography revealed that bovine prolactin and human GH each bound to the same mammary gland proteins, yielding fractions enriched in binding activity and a protein of M(r) 36,000, assumed to be a bovine prolactin receptor. Affinity cross-linking of 125I-labelled human GH to mammary microsomes confirmed that the M(r) 36,000 protein was a bovine prolactin receptor. Binding assays of receptors in microsomes from the mammary tissue of cows and ewes at various stages of the lactational/reproductive cycle indicated developmental regulation of receptor concentration, but not receptor type, as no other bovine prolactin receptor type was detected by affinity cross-linking. These results suggest that differences in the response to prolactin in the mammary gland at various developmental stages in ruminants are not due to the expression of different forms of the prolactin receptor, and the lack of a prolactin effect on established lactation in ruminants is not due to the absence of the M(r) 36,000 form of the prolactin receptor.

Animals↗
PubMed1993

Diagnosis of prostatic carcinoma: value of random transrectal sonographically guided biopsies.

OBJECTIVE: We studied the efficacy of random, transrectal sonographically guided biopsies in the diagnosis of prostatic carcinoma in a high-risk population. SUBJECTS AND METHODS: During a 2-year period, 570 transrectal sonographically guided prostatic biopsies were done because of clinical findings suggestive of prostatic carcinoma. Biopsies of hypoechoic lesions that were suggestive of carcinoma and segmental random biopsies of normal-appearing lobes of the prostate were performed. Transrectal sonographic findings were correlated with results of pathologic examination of the biopsy specimen and with surgical results, when available. RESULTS: Of the 202 patients found to have carcinoma, the carcinoma was detected with directed biopsy in 145 patients (72%). One hundred twenty (71%) of 169 carcinomas were detected with random biopsy when that procedure was performed. Random biopsies were the only method of diagnosing 57 (28%) of the 202 carcinomas, increasing the yield by 39%. CONCLUSION: Yield of carcinoma on transrectal sonographically guided biopsies increases significantly when segmental random biopsies are performed. Transrectal sonographically guided biopsies should include cores through hypoechoic lesions that are suggestive of carcinoma and bilateral segmental random biopsies.

Biopsy, Needle↗
PubMed1993

Colonic adenomas in asymptomatic women with a history of breast cancer.

One hundred ninety-three asymptomatic women with a personal history of breast cancer underwent screening colonoscopy. One hundred sixty-eight women had breast cancer as their only potential risk factor for colonic neoplasia, and 25 had a family history of colorectal neoplasia in addition to their personal history of breast cancer. Among women with breast cancer, increasing age and body weight were each predictive of an increasing prevalence of colonic adenomas. The prevalence of colonic adenomas in women aged 50-75 yr whose only potential risk factor was breast cancer was 18%, and was identical to the prevalence of colonic adenomas in 186 asymptomatic average-risk control women aged 50-75 yr (odds ratio 1.0, 95% CI 0.54-1.87). We conclude that a personal history of breast cancer does not predict a higher prevalence of colonic adenomas.

Adenoma↗
PubMed1993

Colonic neoplasia in asymptomatic persons with negative fecal occult blood tests: influence of age, gender, and family history.

Six hundred twenty-one asymptomatic persons with negative fecal occult blood tests (ages 50-75 yr), including 496 with no known risk factors for colorectal cancer and 125 with a single first-degree relative with a history of colonic neoplasia developed after age 40, underwent screening colonoscopy. Three Dukes A cancers were detected in average-risk persons. The overall prevalence of adenomatous polyps was 27%. Multiple logistic regression analysis revealed that increasing age and male gender were both strong predictors of colonic neoplasia (p < 0.001). A positive family history of a single first-degree relative with colorectal cancer was not associated with an increased prevalence of colonic neoplasia (p = 0.29), although an effect may be present if the relative was < 60 yr at diagnosis. Overall 16% of males and 7% of women > or = 60 yr had at least one adenoma that was large (> or = 1 cm in size), villous or tubulovillous, or had grade 3 dysplasia. We conclude that the prevalence of colonic neoplasia in asymptomatic persons with negative fecal occult blood tests is substantial, particularly in elderly males. A family history of a single first-degree relative diagnosed at age > or = 60 yr with colorectal cancer is not associated with an increased prevalence of colonic adenomas.

Adenoma↗
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↗