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Biomedical subjects

K Carroll

Publications and source records attributed to K Carroll.

At least 55 records · Page 3Linked to original sources
PubMed1999

Comparison of four methodologies for rapid and cost-effective identification of Candida glabrata.

To improve turnaround time and decrease the cost of the identification of Candida glabrata, we evaluated four methods for the detection of trehalose assimilation or fermentation. These methods were compared with the API 20C method (bioMERIEUX, Hazelwood, Mo.) to determine accuracy. We recommend the use of Remel Rapid Trehalose Assimilation Broth because of its rapid, 3-h results, reasonable sensitivity, and low number of false positives.

Candida↗
PubMed1999

The ski7 antiviral protein is an EF1-alpha homolog that blocks expression of non-Poly(A) mRNA in Saccharomyces cerevisiae.

We mapped and cloned SKI7, a gene that negatively controls the copy number of L-A and M double-stranded RNA viruses in Saccharomyces cerevisiae. We found that it encodes a nonessential 747-residue protein with similarities to two translation factors, Hbs1p and EF1-alpha. The ski7 mutant was hypersensitive to hygromycin B, a result also suggesting a role in translation. The SKI7 product repressed the expression of nonpolyadenylated [non-poly(A)] mRNAs, whether capped or uncapped, thus explaining why Ski7p inhibits the propagation of the yeast viruses, whose mRNAs lack poly(A). The dependence of the Ski7p effect on 3' RNA structures motivated a study of the expression of capped non-poly(A) luciferase mRNAs containing 3' untranslated regions (3'UTRs) differing in length. In a wild-type strain, increasing the length of the 3'UTR increased luciferase expression due to both increased rates and duration of translation. Overexpression of Ski7p efficiently cured the satellite virus M2 due to a twofold-increased repression of non-poly(A) mRNA expression. Our experiments showed that Ski7p is part of the Ski2p-Ski3p-Ski8p antiviral system because a single ski7 mutation derepresses the expression of non-poly(A) mRNA as much as a quadruple ski2 ski3 ski7 ski8 mutation, and the effect of the overexpression of Ski7p is not obtained unless other SKI genes are functional. ski1/xrn1Delta ski2Delta and ski1/xrn1Delta ski7Delta mutants were viable but temperature sensitive for growth.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Acute pancreatic transplant rejection: evaluation with dynamic contrast-enhanced MR imaging compared with histopathologic analysis.

PURPOSE: To evaluate the use of dynamic contrast material-enhanced gradient-recalled-echo MR imaging for the diagnosis of acute pancreatic transplant rejection, as confirmed at histopathologic analysis. MATERIALS AND METHODS: Thirty MR imaging studies were performed in 25 patients within 3 days of percutaneous biopsy or pancreatectomy. The mean percentage of parenchymal enhancement (MPPE) at dynamic contrast-enhanced MR imaging was calculated. RESULTS: Biopsy findings were no evidence of rejection (n = 7 [23%]), mild rejection (n = 10 [33%]), moderate (n = 6 [20%]) and severe (n = 2 [7%]) acute rejection, and infarction (n = 5 [17%]). The corresponding MPPEs at 1 minute were 106%, 66%, 62%, 57%, and 3%, respectively. Overlap of cases in the normal and rejection groups occurred; however, using an MPPE cutoff of 100% resulted in a sensitivity of 96%. An MPPE over 120% was seen in the normal group only. The MPPE was significantly greater in the normal group than in the rejection or infarction group (P < .05). CONCLUSION: Dynamic contrast-enhanced MR imaging is highly sensitive for the detection of acute pancreatic transplant rejection. Because of overlap of cases in the normal and rejection groups, percutaneous biopsy may be needed in some cases. Pancreatic allografts with infarction can be clearly identified.

Acute Disease↗
PubMed1999

Effect of cryopreservation on cytochrome P-450 enzyme induction in cultured rat hepatocytes.

In the present study, we evaluated the inducibility of cytochrome P-450 (CYP) CYP1A, CYP2B, CYP3A, and CYP4A by beta-naphthoflavone, phenobarbital, dexamethasone, and clofibric acid, respectively, in primary hepatocyte cultures prepared from both fresh and cryopreserved rat hepatocytes. Rat hepatocytes were successfully thawed and cultured after cryopreservation in liquid nitrogen for up to 1 month. Percentage of total recovery, viable cell recovery, and final viability of the cells were 68%, 72%, and 85%, respectively. Regardless of whether they were cryopreserved or not, cultured hepatocytes exhibited near-normal morphology. Treatment of cryopreserved hepatocytes with beta-naphthoflavone caused an 8-fold increase in 7-ethoxyresorufin O-dealkylase (CYP1A1/2) activity, with an EC50 of 1.5 microM; treatment with phenobarbital caused a 26-fold increase in 7-pentoxyresorufin O-dealkylase (CYP2B1/2) activity, with an EC50 of 10 microM; treatment with dexamethasone caused a 10-fold increase in testosterone 6beta-hydroxylase (CYP3A1/2) activity, with an EC50 of 1.3 microM, whereas treatment with clofibric acid caused a 3-fold increase in lauric acid 12-hydroxylase (CYP4A1-3) activity, with an EC50 of 170 microM. The induction of CYP1A, CYP2B, CYP3A, and CYP4A enzymes by these inducers was confirmed by Western immunoblotting. The patterns of P-450 induction in cryopreserved rat hepatocytes, in terms of concentration response, reproducibility, magnitude, and specificity of response, were similar to those observed in freshly isolated hepatocytes. Additionally, the magnitude and specificity of induction was similar to that observed in vivo in rats. In conclusion, under the conditions examined, cryopreserved rat hepatocytes appear to be a suitable in vitro system for evaluating xenobiotics as inducers of P-450 enzymes.

Animals↗
PubMed1999

Influence of extracellular matrix overlay and medium formulation on the induction of cytochrome P-450 2B enzymes in primary cultures of rat hepatocytes.

The effect of medium formulation, composition of extracellular matrix overlay, and culture dish material on liver microsomal cytochrome P-450 (CYP) 2B induction by phenobarbital (PB) was investigated in primary cultures of rat hepatocytes. When hepatocytes were maintained on Permanox dishes with an overlay of either collagen (type I) or Matrigel, Williams' E medium was superior to other medium formulations in terms of the magnitude of induction of CYP2B on a per milligram microsomal protein basis. Modified Chee's medium (MCM) and hepatocyte culture medium were intermediate in their capacity to sustain induction of CYP2B by PB, and Dulbecco's modified Eagle's medium was slightly less effective. The overall induction of CYP2B activity by PB was, on average, 50% lower in hepatocytes cultured on polystyrene dishes (LUX). Little or no difference was observed between hepatocytes overlaid with collagen and those overlaid with Matrigel. MCM was superior to Williams' E medium in terms of the yield of microsomal protein and the ultrastructural features of the hepatocyte monolayers. CYP2B induction by PB was optimal after 3 days of treatment in either medium. CYP1A, CYP3A, and CYP4A activities could be induced in vitro by prototypical inducing agents in hepatocytes cultured on Permanox dishes with MCM and a Matrigel overlay to comparable levels observed in vivo. The results of these studies show that medium formulation and culture vessel material, but not the type of extracellular matrix overlay, have significant effects on the induction of CYP enzymes in cultured rat hepatocytes maintained in a sandwich configuration.

Animals↗
PubMed1998

Casodex (bicalutamide) 150-mg monotherapy compared with castration in patients with previously untreated nonmetastatic prostate cancer: results from two multicenter randomized trials at a median follow-up of 4 years.

OBJECTIVES: To compare the efficacy, tolerability, and quality of life benefits of bicalutamide (Casodex) 150-mg/day monotherapy and castration in previously untreated nonmetastatic (M0) advanced prostate cancer. METHODS: A total of 480 patients with Stage T3/T4 nonmetastatic disease randomly received oral bicalutamide 150 mg/day or castration (either bilateral orchiectomy or goserelin acetate [Zoladex] 3.6 mg every 28 days) in a 2:1 ratio in two open multicenter studies (studies 306 and 307). The design of these studies was similar to allow a pooled analysis. RESULTS: In the combined survival analysis, at median follow-up of 202 and 205 weeks in studies 306 and 307, respectively, with 31% of the cases resulting in death, bicalutamide 150-mg monotherapy was statistically equivalent to castration; the risk of death from any cause was 7% less with bicalutamide than with castration (hazard ratio [HR] = 0.93). Data on time to treatment failure and objective progression could not be pooled, as results for these end points differed between the trials. In study 306, bicalutamide 150-mg monotherapy increased time to objective progression (HR = 0.58; P = 0.033) and treatment failure (HR = 0.66; P = 0.074), whereas in study 307, time to progression (HR = 1.35; P = 0.0471) and treatment failure (HR = 1.24; P = 0.097) favored castration. Bicalutamide therapy showed significant advantages over castration for both sexual interest (P = 0.029) and physical capacity (P = 0.046). Bicalutamide 150-mg monotherapy was well tolerated. CONCLUSIONS: Bicalutamide 150-mg monotherapy provides a similar survival outcome to castration in previously untreated patients with nonmetastatic advanced prostate cancer and confers statistically significant benefits over castration with respect to sexual interest and physical capacity.

Aged↗
PubMed1998

Crohn's disease: new imaging techniques.

This chapter reviews the current state of imaging in Crohn's disease. Imaging plays an important role in the diagnosis and management of Crohn's disease. Imaging is complementary to the clinical assessment of the patient and other investigations including endoscopy. The choice of imaging modality depends on the clinical circumstances and local availability of resources and skills. Close co-operation between clinicians and radiologists is important. Barium radiology remains important. Magnetic resonance imaging (MRI) and ultrasound (US) should get special consideration because of the lack of ionizing radiation. MRI is particularly good at demonstrating the perianal complication of Crohn's disease. Computer tomography (CT) and US can be used for image-guided drainage of abscesses.

Barium Sulfate↗
PubMed1998

Comparison of nine commercially available enzyme-linked immunosorbent assays for detection of Giardia lamblia in fecal specimens.

Overall performance, including ease of use, total hands-on time, incubation and processing times, sensitivity, and specificity, of each of nine enzyme-linked immunosorbent assays (ELISAs) were compared by using 222 individual fecal samples submitted for the detection of Giardia lamblia. The assays evaluated were manufactured by Alexon, Inc., Cambridge Biotech Corp., Meridian, Inc., and Trend Scientific, Inc. All assays used polyclonal antibodies except the "new and improved" Microplate (direct and diluted methods) by Alexon, which is a monoclonal antibody assay. Seventy specimens were positive for G. lamblia by ELISA, ova and parasite test, and/or direct fluorescent-antibody assay. One hundred fifty two were negative by all three methods. Sensitivities and specificities ranged from 88.6 to 100% and 99.3 to 100%, respectively. The total hands-on time needed to run one specimen ranged from 1 min to 2 min 17 s per specimen. All except one commercially available ELISA were found to be rapid, sensitive, and specific for the detection of G. lamblia in fecal specimens.

Animals↗
PubMed1998

Ski6p is a homolog of RNA-processing enzymes that affects translation of non-poly(A) mRNAs and 60S ribosomal subunit biogenesis.

We mapped and cloned SKI6 of Saccharomyces cerevisiae, a gene that represses the copy number of the L-A double-stranded RNA virus, and found that it encodes an essential 246-residue protein with homology to a tRNA-processing enzyme, RNase PH. The ski6-2 mutant expressed electroporated non-poly(A) luciferase mRNAs 8- to 10-fold better than did the isogenic wild type. No effect of ski6-2 on expression of uncapped or normal mRNAs was found. Kinetics of luciferase synthesis and direct measurement of radiolabeled electroporated mRNA indicate that the primary effect of Ski6p was on efficiency of translation rather than on mRNA stability. Both ski6 and ski2 mutants show hypersensitivity to hygromycin, suggesting functional alteration of the translation apparatus. The ski6-2 mutant has normal amounts of 40S and 60S ribosomal subunits but accumulates a 38S particle containing 5'-truncated 25S rRNA but no 5.8S rRNA, apparently an incomplete or degraded 60S subunit. This suggests an abnormality in 60S subunit assembly. The ski6-2 mutation suppresses the poor expression of the poly(A)- viral mRNA in a strain deficient in the 60S ribosomal protein L4. Thus, a ski6 mutation bypasses the requirement of the poly(A) tail for translation, allowing better translation of non-poly(A) mRNA, including the L-A virus mRNA which lacks poly(A). We speculate that the derepressed translation of non-poly(A) mRNAs is due to abnormal (but full-size) 60S subunits.

Amino Acid Sequence↗
PubMed1998

Evaluation of biopsy needles and prototypic needle guide devices for percutaneous biopsy with CT fluoroscopic guidance in simulated organ tissue.

The authors evaluated accuracy and success rates for placement of fine-aspiration, core, and coaxial biopsy needles in pork meat with three needle guide devices and computed tomographic fluoroscopic guidance. Accuracy and reliability with a metallic sponge-forceps needle holder was equal to or greater than those with other devices, and it was preferred by operators due to its lighter weight and single-handed manipulation. All needle holders functioned poorly with thin-walled needles.

Animals↗
PubMed1998

Molecular genetics of root gravitropism and waving in Arabidopsis thaliana.

When Arabidopsis thaliana seedlings grow embedded in an agar-based medium, their roots grow vertically downward. This reflects their ability to sense the gravity vector and to position their tip parallel to it (gravitropism). We have isolated a number of mutations affecting root gravitropism in Arabidopsis thaliana. One of these mutations, named arg1, affects root and hypocotyl gravitropism without promoting defects in starch content or in the ability of seedlings' organs to respond to plant hormones. The ARG1 gene was cloned and shown to code for a protein with a J domain at its amino terminus and a second sequence motif found in several cytoskeleton binding proteins. Mutations in the AGR1 locus promote a strong defect in root gravitropism. Some alleles also confer an increased root resistance to exogenous ethylene and an increased sensitivity to auxin. AGR1 was cloned and found to encode a putative transmembrane protein which might be involved in polar auxin transport, or in regulating the differential growth response to gravistimulation. When Arabidopsis seedlings grow on the surface of agar-based media tilted backward, their roots wave. That wavy pattern of root growth derives from a combined response to gravity, touch and other surface-derived stimuli. It is accompanied by a reversible rotation of the root tip about its axis. A number of mutations affect the presence or the shape of root waves on tilted agar-based surfaces. One of them, wvc1, promotes the formation of compressed root waves under these conditions. The physiological and molecular analyses of this mutant suggest that a tryptophan-derived molecule other than IAA might be an important regulator of the curvature responsible for root waving.

Arabidopsis↗
PubMed1997

Now you see it, now you don't: a comparison of traditional versus random-effects regression models in the analysis of longitudinal follow-up data from a clinical trial.

To illustrate the limitations of commonly used methods of handling missing data when using traditional analysis of variance (ANOVA) models and highlight the relative advantages of random-effects regression models, multiple analytic strategies were applied to follow-up data from a clinical trial. Traditional ANOVA and random-effects models produced similar results when underlying assumptions were met and data were complete. However, analyses based on subsamples, to which investigators would have been limited with traditional models, would have led to different conclusions about treatment effects over time than analyses based on intention-to-treat samples using random-effects regression models. These findings underscore the advantages of models that use all data collected and the importance of complete data collection to minimize sample bias.

Adult↗
PubMed1997

Pemberton pericapsular osteotomy to treat a dysplastic hip in cerebral palsy.

We reviewed the results of Pemberton pericapsular osteotomy in nineteen hips (fifteen patients) that were subluxated (fifteen hips) or dislocated (two hips) or had severe acetabular dysplasia (two hips) secondary to spastic cerebral palsy. At least one concomitant procedure was performed in fifteen hips. These procedures included an intertrochanteric osteotomy to correct excessive femoral anteversion or valgus deformity of the neck-shaft angle (thirteen hips), a soft-tissue release (nine hips), and an open reduction (three hips). Four hips had no concomitant procedure. Five of the nineteen hips were painful preoperatively. The average age of the patients at the time of the index operation was seven years and nine months (range, three years and five months to twelve years and three months). The average duration of follow-up was ten years and nine months (range, three years and one month to nineteen years and nine months). All osteotomy sites healed without complications. At the latest follow-up examination, all of the hips were pain-free and satisfactorily reduced and none of the patients had deterioration in function. The average center-edge angle was -5 degrees (range, -45 to 18 degrees) preoperatively and 38 degrees (range, 17 to 53 degrees) at the latest follow-up examination. The average migration index of Reimers was 55 per cent (range, 30 to 100 per cent) preoperatively compared with 12 per cent (range, 0 to 46 per cent) at the latest follow-up examination. Sixteen of the nineteen hips were followed until closure of the triradiate cartilage. There were no instances of posterior uncovering or osteonecrosis of the femoral head or premature closure of the triradiate physeal cartilage leading to deficient acetabular coverage. Our results suggest that good clinical and radiographic results can be achieved with the Pemberton pericapsular osteotomy, with simultaneous intertrochanteric osteotomy and soft-tissue release when indicated, as treatment for subluxation or dislocation of the hip or acetabular dysplasia in cerebral palsy.

Cerebral Palsy↗
PubMed1996

Intracellular distribution of Arf proteins in mammalian cells. Arf6 is uniquely localized to the plasma membrane.

Subcellular distributions of the five human Arf proteins were examined, using a set of isoform-specific polyclonal and a pan-Arf monoclonal antibodies. Subcellular fractionation of cultured mammalian cells allowed the demonstration that Arf6 is uniquely localized to the plasma membranes of Chinese hamster ovary cells. The plasma membrane distrubution was unaffected by either GTPgammaS (guanosine 5'-O-(3-thio)triphosphate) or brefeldin A, an activator and inhibitor of Arf activities, respectively. In contrast, Arf proteins 1, 3, 4, and 5 were predominantly cytosolic but could be recruited to a variety of intracellular membranes, but not plasma membranes, upon incubation in the presence of GTPgammaS. The GTPgammaS-promoted binding of the cytosolic Arf proteins to membranes was blocked by brefeldin A. The stable association of Arf6 with plasma membranes and the insensitivity of its localization to either GTPgammaS or brefeldin A revealed a clear distinction between Arf6 and the other Arf isoforms. Localization of Arf6 to the plasma membrane suggests a unique cellular role for this isoform at the plasma membrane, but failure to find endogenous Arf6 on endocytic structures, including clathrin-coated vesicles, appears inconsistent with the proposed role of Arf6 in assembly of coat structures or endosomes in transfected fibroblasts (1,2).

ADP-Ribosylation Factors↗
PubMed1996

Use of a single slide trichrome-stained concentrate for the detection of intestinal parasites. Stained concentration procedure for ova and parasites.

The detection and identification of intestinal parasites was studied using a single slide of a trichrome-stained concentrate made from a cupric-polyvinyl alcohol (PVA)-preserved specimen. When saline was used in place of formalin in the concentration procedure, it was possible to adequately stain the concentrate with a modified-trichrome stain. This was compared to a more traditional two-slide ova and parasite (O&P) procedure. Of the 1,000 specimens evaluated, a total of 261 parasites were detected using the single slide, modified trichrome-stained concentrate compared to 249 from the formalin/Hemo-De wet mount and 226 from the unconcentrated trichrome stain. The detection rate of the single slide method was comparable to the combined detection rate of the two-slide method. The saline/Hemo-De concentration procedure has the advantage of using nontoxic saline in place of formaldehyde. This new method is more cost-effective because it requires the processing and evaluation of only one slide.

Animals↗
PubMed1996

Microbiology and laboratory diagnosis of upper respiratory tract infections.

In the article that follows, Carroll and Reimer address a number of issues related to the clinical and laboratory diagnosis of upper respiratory tract infections. These syndromes occur with great frequency in both adults and children and have tremendous economic impact, related not only to lost productivity in the workplace but also to the frequent prescription by physicians of antibiotics, even when the etiologic agents of infection almost certainly are not bacteria. Most of these infections are diagnosed clinically, and specimens for microbiological identification are not obtained. Indeed, the difficulty in obtaining microbiological specimens that are not contaminated by resident colonizing flora often results in laboratory culture reports of dubious clinical value. As the authors note, the most standardized procedures are for the diagnosis of pharyngitis due to Streptococcus pyogenes. The preferred culture methods are reviewed as are the sensitivities, specificities, and limitations of rapid direct tests for group A streptococcal antigens. Currently, as the authors emphasize, a negative direct test mandates a conventional culture for S. pyogenes. More problematic are requests for isolation of other streptococci, Haemophilus species, corynebacteria, and gram-negative bacteria. Given limited resources, cost-containment imperatives, and the absence of clear evidence that these organisms are pharyngeal pathogens associated with important sequelae, my laboratory does not attempt to isolate these bacteria unless the ordering physician has directly consulted with me (the laboratory director). Carroll and Reimer emphasize that nasopharyngeal cultures have no place in the microbiological diagnosis of otitis media and that diagnostic tympanocentesis is the only procedure for obtaining specimens that yield reliable microbiological findings. They also point out the futility of using swabs to obtain material for the diagnosis of otitis externa, since the external auditory canal cannot be decontaminated sufficiently to obtain a meaningful culture result. Finally, the authors address the available methods for obtaining specimens to establish the etiology of sinusitis. For microbiological diagnosis, direct antral puncture has been the method of choice for many years. However, otorhinolaryngologists now obtain many specimens endoscopically. It probably is not possible to obtain specimens by this method without contamination by normal upper respiratory flora. Thus, results of cultures of endoscopic specimens are more difficult to interpret. For patients with complicated illnesses, use of the diagnostic "gold standard" of antral puncture, as well as biopsy with histopathologic correlation, should be encouraged.

Bacterial Infections↗
PubMed1996

Ochrobactrum anthropi meningitis in pediatric pericardial allograft transplant recipients.

An epidemiologic investigation was done after 3 patients contracted Ochrobactrum anthropi meningitis at one hospital in October 1994. Neurosurgical patients with pericardial tissue implants were at greater risk of infection than other neurosurgical patients (3/14 vs. 0/566; P<.001). Cultures of implants removed from 2 case-patients, an implant at implantation, a nonimplanted pericardial tissue, and an unwrapped but unopened bottle of Hank's balanced salt solution (HBSS) grew O. anthropi. Patient and tissue isolates had identical genotypes; the isolate from the HBSS bottle had a unique genotype. Culture samples from an unopened HBSS bottle and from pericardial tissue grew Pseudomonas stutzeri of the same genotype; however, no P. stutzeri infections were detected. The investigation documented intrinsic P. stutzeri contamination of HBSS. O. anthropi contamination of tissues occurred during processing, possibly due to extrinsic contamination of HBSS. Active surveillance is needed to detect infection in patients receiving transplanted tissues, and rigorous infection control practice are necessary during tissue harvesting and processing to ensure sterility.

Alcaligenes↗