Search PubMed⌕ Search

Biomedical subjects

M Charron

Publications and source records attributed to M Charron.

At least 37 records · Page 2Linked to original sources
PubMed1999

A novel 14-base-pair regulatory element is essential for in vivo expression of murine beta4-galactosyltransferase-I in late pachytene spermatocytes and round spermatids.

During murine spermatogenesis, beginning in late pachytene spermatocytes, the beta4-galactosyltransferase-I (beta4GalT-I) gene is transcribed from a male germ cell-specific start site. We had shown previously that a 796-bp genomic fragment that flanks the germ cell start site and contains two putative CRE (cyclic AMP-responsive element)-like motifs directs correct male germ cell expression of the beta-galactosidase reporter gene in late pachytene spermatocytes and round spermatids of transgenic mice (N. L. Shaper, A. Harduin-Lepers, and J. H. Shaper, J. Biol. Chem. 269:25165-25171, 1994). We now report that in vivo expression of beta4GalT-I in developing male germ cells requires an essential and previously undescribed 14-bp regulatory element (5'-GCCGGTTTCCTAGA-3') that is distinct from the two CRE-like sequences. This cis element is located 16 bp upstream of the germ cell-specific start site and binds a male germ cell protein that we have termed TASS-1 (transcriptional activator in late pachytene spermatocytes and round spermatids 1). The presence of the Ets signature binding motif 5'-GGAA-3' on the bottom strand of the TASS-1 sequence (underlined sequence) suggests that TASS-1 is a novel member of the Ets family of transcription factors. Additional transgenic analyses established that an 87-bp genomic fragment containing the TASS-1 regulatory element was sufficient for correct germ cell-specific expression of the beta-galactosidase reporter gene. Furthermore, when the TASS-1 motif was mutated by transversion, within the context of the original 796-bp fragment, transgene expression was reduced 12- to 35-fold in vivo.

Animals↗
PubMed1999

Pediatric inflammatory bowel disease: assessment with scintigraphy with 99mTc white blood cells.

PURPOSE: To evaluate the sensitivity and specificity of scintigraphy with technetium 99m white blood cells (WBC) for detection of colonic inflammation in children with and children without inflammatory bowel disease (IBD). MATERIALS AND METHODS: In 215 patients, uptake of 99mTc WBC in 3,440 bowel segments was graded. In 137 of the 215 patients, the 99mTc WBC scans were interpreted blindly and findings compared with results at colonoscopy and endoscopic biopsy. Planar, single photon emission computed tomographic, and maximum-activity-projection images were reviewed together. In 78 children without recent endoscopic biopsy results, 99mTc WBC scan findings were compared with laboratory values, the gastroenterologist's initial clinical assessment, and findings at long-term clinical follow-up. RESULTS: In 128 of 137 children with recent biopsies, findings at histologic examination and on 99mTc WBC scans were correlated. There were seven false-negative and two false-positive studies. Sensitivity was 90%, specificity 97%, positive predictive value 97%, negative predictive value 93%, prevalence of disease 53%, and overall accuracy 93%. In 75 of 78 (96%) children without recent biopsies, 99mTc WBC scan findings were consistent with the laboratory values, gastroenterologist's clinical assessment, and long-term clinical follow-up findings. CONCLUSION: Scintigraphy with 99mTc WBC is a useful noninvasive diagnostic test to determine the extent and distribution of inflammation in children with IBD.

Biopsy↗
PubMed1999

Oral versus initial intravenous therapy for urinary tract infections in young febrile children.

BACKGROUND: The standard recommendation for treatment of young, febrile children with urinary tract infection has been hospitalization for intravenous antimicrobials. The availability of potent, oral, third-generation cephalosporins as well as interest in cost containment and avoidance of nosocomial risks prompted evaluation of the safety and efficacy of outpatient therapy. METHODS: In a multicenter, randomized clinical trial, we evaluated the efficacy of oral versus initial intravenous therapy in 306 children 1 to 24 months old with fever and urinary tract infection, in terms of short-term clinical outcomes (sterilization of the urine and defervescence) and long-term morbidity (incidence of reinfection and incidence and extent of renal scarring documented at 6 months by 99mTc-dimercaptosuccinic acid renal scans). Children received either oral cefixime for 14 days (double dose on day 1) or initial intravenous cefotaxime for 3 days followed by oral cefixime for 11 days. RESULTS: Treatment groups were comparable regarding demographic, clinical, and laboratory characteristics. Bacteremia was present in 3.4% of children treated orally and 5.3% of children treated intravenously. Of the short-term outcomes, 1) repeat urine cultures were sterile within 24 hours in all children, and 2) mean time to defervescence was 25 and 24 hours for children treated orally and intravenously, respectively. Of the long-term outcomes, 1) symptomatic reinfections occurred in 4.6% of children treated orally and 7.2% of children treated intravenously, 2) renal scarring at 6 months was noted in 9.8% children treated orally versus 7.2% of children treated intravenously, and 3) mean extent of scarring was approximately 8% in both treatment groups. Mean costs were at least twofold higher for children treated intravenously ($3577 vs $1473) compared with those treated orally. CONCLUSIONS: Oral cefixime can be recommended as a safe and effective treatment for children with fever and urinary tract infection. Use of cefixime will result in substantial reductions of health care expenditures.

Acute Disease↗
PubMed1998

The increased level of beta1,4-galactosyltransferase required for lactose biosynthesis is achieved in part by translational control.

beta1,4-Galactosyltransferase (beta4GalT-I) participates in both glycoconjugate biosynthesis (ubiquitous activity) and lactose biosynthesis (mammary gland-specific activity). In somatic tissues, transcription of the mammalian beta4GalT-I gene results in a 4.1-kb mRNA and a 3.9-kb mRNA as a consequence of initiation at two start sites separated by approximately 200 bp. In the mammary gland, coincident with the increased beta4GalT-I enzyme level ( approximately 50-fold) required for lactose biosynthesis, there is a switch from the 4.1-kb start site to the preferential use of the 3.9-kb start site, which is governed by a stronger tissue-restricted promoter. The use of the 3.9-kb start site results in a beta4GalT-I transcript in which the 5'- untranslated region (UTR) has been truncated from approximately 175 nt to approximately 28 nt. The 5'-UTR of the 4.1-kb transcript [UTR(4.1)] is predicted to contain extensive secondary structure, a feature previously shown to reduce translational efficiency of an mRNA. In contrast, the 5'-UTR of the 3.9-kb mRNA [UTR(3.9)] lacks extensive secondary structure; thus, this transcript is predicted to be more efficiently translated relative to the 4.1-kb mRNA. To test this prediction, constructs were assembled in which the respective 5'-UTRs were fused to the luciferase-coding sequence and enzyme levels were determined after translation in vitro and in vivo. The luciferase mRNA containing the truncated UTR(3.9) was translated more efficiently both in vitro (approximately 14-fold) and in vivo (3- to 5-fold) relative to the luciferase mRNA containing the UTR(4.1). Consequently, in addition to control at the transcriptional level, beta4GalT-I enzyme levels are further augmented in the lactating mammary gland as a result of translational control.

Animals↗
PubMed1998

Distribution of acute bowel inflammation determined by technetium-labeled white blood cells in children with inflammatory bowel disease.

Knowledge of the distribution of disease in patients with inflammatory bowel disease is important because it has diagnostic, prognostic, and therapeutic implications. We studied 215 patients with 99mTc-HMPAO-white blood cell scans, of whom 80 had Crohn's disease (CD), 34 had active ulcerative colitis (UC), and 31 were controls. In our 77 cases of active CD, uptake was seen exclusively in the small bowel in 18% of patients, only the large bowel in 44%, and both the large and small bowel in 38% of patients. Discontinuous colitis was seen in 63 of these patients. In the 29 cases of active UC, the uptake involved the entire colon in 50% of patients, extended farther than the sigmoid in 27% of patients, and was limited to the rectosigmoid in 23%. In the 29 cases of active UC, four of the scans incorrectly revealed discontinuous accumulation of 99mTc-HMPAO-WBC. In 31 controls, no significant colonic uptake was seen. Isolated small bowel involvement with CD is observed less frequently in children undergoing 99mTc-HMPAO-WBC scanning than in adults. In children, the segmental distribution of inflammation as depicted with 99mTc-HMPAO-WBC is similar to the radiologic distribution.

Adolescent↗
PubMed1998

Use of technetium-tagged white blood cells in patients with Crohn's disease and ulcerative colitis: is differential diagnosis possible?

BACKGROUND: Studies have suggested that scans with technetium-tagged white blood cells (WBC-Tc99m) may be equal to endoscopy in the assessment of extent and activity of inflammatory bowel disease (IBD). OBJECTIVE: We have retrospectively examined the accuracy of WBC-Tc99m scans in differentiating continuous from discontinuous colitis in pediatric IBD. MATERIALS AND METHODS: There were 207 children in the study (96 boys, 111 girls, median age 13 years). This included 29 controls - children with no gastrointestinal disease (NL) who underwent WBC-Tc99m scans for other medical problems. Scans were obtained at 30 minutes and 2-4 hours following injection. Scans were interpreted as showing continuous colitis, discontinuous colitis, or no colitis. RESULTS: In the 77 children with active Crohn's disease (CD) of the colon, the scans revealed discontinuous uptake in 63 children and continuous uptake in 14. In the 29 children with ulcerative colitis (UC), 23 scans showed continuous uptake and 6 revealed discontinuous uptake. Two of these 6 showed focal activity near the appendix, and subclinical appendicitis could not be excluded. Another child was bleeding and the scan could have been misinterpreted as showing small- bowel inflammation. In the last three patients, skip areas were clearly identifiable. In none of these last three patients were the biopsies typical of CD (i. e., no granuloma was identified) nor was inflammation patchy. In summary, of the 106 scans showing inflammation, 6 were classified into the wrong group. CONCLUSION: These data show that WBC-Tc99m scanning can be useful in distinguishing discontinuous from continuous colitis.

Adolescent↗
PubMed1998

Beta1,4-galactosyltransferase and lactose biosynthesis: recruitment of a housekeeping gene from the nonmammalian vertebrate gene pool for a mammary gland specific function.

Beta1,4-galactosyltransferase (beta4GalT-I) is a constitutively expressed trans-Golgi enzyme, widely distributed in vertebrates, which synthesizes the beta4-N-acetyllactosamine structure commonly found in glycoconjugates. In mammals beta4GalT-I has been recruited for a second biosynthetic function, the production of lactose; this function takes place exclusively in the lactating mammary gland. In preparation for lactose biosynthesis, beta4GalT-I enzyme levels are increased significantly. We show that mammals have evolved a two-step mechanism to achieve this increase. In step one there is a switch to the use of a second transcriptional start site, regulated by a stronger, mammary gland-restricted promoter. The transcript produced is distinguished from its housekeeping counterpart by the absence of approximately 180 nt of 5'-untranslated sequence. In step two, this truncated transcript is translated more efficiently, relative to the major transcript expressed in all other somatic tissues.

Animals↗
PubMed1998

Comparison of the sensitivity of early versus delayed imaging with Tc-99m HMPAO WBC in children with inflammatory bowel disease.

The difference in sensitivity of early imaging at 30 minutes after injection of Tc-99m HMPAO WBC versus delayed imaging at 2 or 3 hours for depiction of active inflammation in children with inflammatory bowel disease was established. The charts of 220 children who had early (30-minute) and delayed (2 or 3 hours) imaging performed for evaluation of inflammatory bowel disease were reviewed. There were 107 boys and 113 girls (average age, 12 years; median, 13 years). The bowel was divided into eight segments (with the total for all patients being 3,520) graded on a scale of 0 to 6 (with reference points in the iliac crest and liver). Any grade > or = 1 was abnormal. The uptake in each segment was summed. One hundred and twenty-two studies were abnormal (55%). The average uptake in the early images was 5.1 +/- 0.41 and that in the late images was 9.3 +/- 0.64. The Friedman nonparametric test of comparison of rank was significant at the 0.001 level. One hundred and five patients had abnormal studies at 30 minutes (88%). An additional 12% of patients had abnormal studies only on the late images. There were 245 abnormal segments at 30 minutes and 413 abnormal segments at 2 or 3 hours. When the uptake was analyzed segment by segment, 62 patients (52%) had abnormal segments at 30 minutes but also had additional abnormal segments at 3 hours. Sensitivity of Tc-99m HMPAO WBC imaging was significantly improved when late imaging was performed.

Adolescent↗
PubMed1998

Characterization of late abdominal accumulation of 99Tcm-HMPAO leukocytes in a large population of children.

We retrospectively evaluated the incidence of late accumulation of 99Tcm-HMPAO leukocytes (99Tcm-WBC) in the right lower quadrant of a large population of children and characterized some predictive patterns that would enable differentiation of active inflammation from this late occasional accumulation of 99Tcm-WBC. We reviewed the charts of 211 children. The first group evaluated consisted of 79 controls: 30 normal children with no gastrointestinal disease, but who underwent 99Tcm-WBC scanning for other medical problems, and 49 children who had non-specific gastrointestinal (GI) complaints, but had no demonstrable inflammatory bowel disease by conventional diagnostic methods. The second group consisted of 132 children with inflammatory bowel disease: 80 children with Crohn's disease (CD), 34 with ulcerative colitis (UC) and 18 with indeterminate colitis (IC). Children were imaged at 30 min and 3 h. Fifteen (19%) of the 79 controls scanned showed accumulation of 99Tcm-WBC in the right lower quadrant at 3 h and none at 30 min. Of those 15, 8 were from the control population and 7 from the group with non-specific GI complaints and negative work-ups. There was no uptake in other segments of the bowel. The accumulation was faint, of lesser intensity than in the iliac wing, and diffuse, such that identification of a specific loop of involved bowel was not possible. Migration of the 99Tcm-WBC distal to the terminal ileum was demonstrated. The other 64 children in the control group showed no accumulation of 99Tcm-WBC at any time during their scans. All 79 scans were blindly interpreted as normal studies. There were no false-positive readings encountered in the 132 children with inflammatory bowel disease (80 CD, 34 UC, 18 IC) when the aforementioned characteristics of the late accumulation of 99Tcm were used to differentiate inflammation from this physiological excretion. In conclusion, the late accumulation of 99Tcm-WBC in the right lower quadrant is characterized by (1) accumulation at no less that 3 h, (2) no accumulation in other segments of the bowel, (3) faint accumulation of lesser intensity than in the iliac wing, (4) a diffuse accumulation pattern and (5) migration of the 99Tcm-WBC into the caecum and ascending colon over time. Recognition of this excretion pattern enables differentiation of active Crohn's disease of the small bowel from migration and accumulation of 99Tcm-WBC in the right lower quadrant of the abdomen.

Abdomen↗
PubMed1998

Effect of pyrazoloacridine (NSC 366140) on DNA topoisomerases I and II.

Pyrazoloacridine (PA), an acridine congener with an unknown mechanism of action, has shown selective activity against solid tumor cells, cytotoxicity in noncycling and hypoxic cells, and promising antitumor activity in Phase I clinical trials. In the present study, the effect of PA on topoisomerase (topo) activity was evaluated using yeast strains lacking functional topo I or II, mammalian cell nuclear extracts, purified samples of mammalian topo I and topo II, and intact mammalian tissue culture cells. Clonogenic assays revealed that PA cytotoxicity in yeast strains was unaffected by selective loss of topo I or topo II activity. On the other hand, enzyme assays revealed that 2-4 microM PA abolished the catalytic activity of both topo I and topo II in vitro. In contrast to topotecan and etoposide, PA did not stabilize covalent topo-DNA complexes. Instead, PA inhibited topotecan-induced stabilization of covalent topo I-DNA complexes and etoposide-induced stabilization of topo II-DNA complexes in vitro and in intact cells. Consistent with these results, colony-forming assays indicated that short-term PA exposure inhibited the cytotoxicity of topotecan and etoposide, whereas prolonged PA exposure was itself toxic to these cells. Accumulation studies revealed that PA was concentrated as much as 250-fold in drug-treated cells, resulting in intranuclear concentrations that far exceeded those required to inhibit topo I and topo II. Collectively, these results not only suggest that PA can target both topo I and topo II at clinically achievable concentrations but also indicate that its mechanism is distinct from topo I and topo II poisons presently licensed for clinical use.

Acridines↗
PubMed1998

Hoarding: a symptom, not a syndrome.

BACKGROUND: Hoarding behavior in humans spans a continuum from normal collecting to pathological self-neglect and can be associated with a variety of psychiatric disorders. METHOD: The authors summarize research in the past 15 years characterizing hoarding behavior in groups of college students, in nonclinical populations of self-named "pack rats," in outpatients treated for obsessive-compulsive disorder (OCD), and in individual pathological hoarders presented in psychiatric case reports. Two new case reports of pathological hoarding are presented here. RESULTS: The literature suggests, as do the 2 case reports presented, that certain factors may be common to all groups of hoarders, as they all show poor insight, lack of resistance to the compulsion to hoard, and poor treatment motivation. CONCLUSION: Possible biological and psychosocial determinants of pathological hoarding include association with schizophrenia, OCD, and tic disorders, as well as a possible link through the neurotransmitter dopamine. Management issues range from psychopharmacologic treatment with antipsychotic medication to behavioral therapy and environmental manipulation.

Age Factors↗
PubMed1997

Radioiodine treatment of juvenile Graves disease.

Ablation of the thyroid gland with radioactive iodine-I131 is an effective and safe method of therapy for older children and adolescents, as with adults, to treat hyperthyroidism of Graves disease (Graves-Basedow disease). The use of radioiodine as initial therapy or, as more often, the second line of therapy following antithyroid drug treatment is highly efficacious and rarely associated with short-term or long-term side effects. The indications for radioiodine therapy are failure of antithyroid drug therapy, idiosyncratic hypersensitivity reactions to antithyroid drugs, contraindications for surgical therapy including patients who refuse surgery, and the desirability to permanently prevent the development of hyperthyroidism. The treatment will induce permanent primary hypothyroidism within months after the use of ablative doses of radioiodine. The safety and simplicity of clinical management with L-thyroxine therapy for hypothyroidism favor radioiodine therapy for Graves disease over the potential risks from treatment with antithyroid drugs or surgery, and from untreated or relapsing hyperthyroidism. Radioiodine therapy is associated with the lowest morbidity and mortality among the currently available methods of therapy for Graves disease.

Adolescent↗
PubMed1997

Inflammatory bowel disease in pediatric patients.

Optimal management of chronic idiopathic inflammatory bowel disease requires determination of disease localization and intensity. Scintigraphy with the use of 99mTc-HMPAO-White Blood Cells (99mTc-HMPAO-WBC) is a relatively new noninvasive nuclear medicine procedure. We have evaluated more than 230 children and have found a high correspondence between the disease distribution shown by the 99mTc-HMPAO-WBC scan and that shown by endoscopic, radiologic, or surgical methods. Additionally the 99mTc-HMPAO-WBC scan has the ability of identifying extra intestinal site of inflammation, such as appendicitis and others. The erythrocyte sedimentation rate, the most frequently used indicator of disease activity in the clinical setting, has better correlation with the scan scores than the clinical activity index. The 99mTc-HMPAO-WBC scan is reliable in differentiating Crohn's disease from ulcerative colitis. Some patients because of unequivocal demonstrable small bowel uptake are reclassified from ulcerative colitis to Crohn's disease. The medication regimen is frequently altered because of the intensity of uptake displayed by the 99mTc-HMPAO-WBC scan. It is a practical and safe study even in an acutely ill patient who may not tolerate endoscopic or radiological study. At our institution, the 99mTc-HMPAO-WBC scan is now part of the initial evaluation, and follow-up of patients with inflammatory bowel disease. In conclusion the 99mTc-HMPAO-WBC is excellent for the detection, localization and characterization of inflammatory bowel disease in children. Compared with the other methods of investigation this study requires no bowel preparation, is noninvasive and has excellent diagnostic accuracy.

Child↗
PubMed1996

Pain palliation with strontium-89 in children with metastatic disease.

We report two cases of children with metastatic bone disease who received strontium-89 intravenously. An 11-year-old boy with stage IV neuroblastoma received 50 microCi/kg of strontium-89. He had a good response, and his pain abated to the point that he could be taken off IV Dilaudid and was discharged from the hospital. A 7-year-old girl with the diagnosis of squamous cell carcinoma of the lung disclosed minimal increased uptake on a bone scan. Following the strontium-89 therapy, she did not have any significant improvement in pain, probably due to the minimal osteoblastic activity evidenced by the minimal abnormalities on the bone scan. Until this report there has been no reported case of using strontium-89 in the treatment of children with metastatic disease.

Analgesics, Opioid↗
PubMed1996

Is urine culture necessary to rule out urinary tract infection in young febrile children?

OBJECTIVE: To determine whether the absence of pyuria on the enhanced urinalysis can be used to eliminate the diagnosis of urinary tract infection, avoiding the need for urine culture and sparing large health care expenditures. DESIGN: Results of an enhanced urinalysis (hemocytometer counts and interpretation of Gram-stained smears) performed on uncentrifuged urine specimens obtained by catheter were correlated with urine cultures in young febrile children at the Children's Hospital of Pittsburgh Emergency Department. In a group of 4253 children (95% febrile) less than 2 years of age, pyuria was defined as > or = 10 white blood cells/mm3, bacteriuria as any bacteria on any of 10 oil immersion fields in a Gram-stained smear and a positive culture as > or = 50,000 colony-forming units/ml. A subgroup of 153 children with their first diagnosed urinary tract infection were enrolled in a separate treatment trial, acute phase reactants (peripheral white blood cell count, erythrocyte sedimentation rate and C-reactive protein) were obtained and 99Tc-dimercaptosuccinic acid renal scans were performed. RESULTS: The presence of either pyuria or bacteriuria and the presence of both pyuria and bacteriuria have the highest sensitivity (95%) and positive predictive value (85%), respectively, for identifying positive urine cultures. Because a white blood cell count in a hemocytometer is the technically simpler component of the enhanced urinalysis, we chose to analyze the false negative results and achievable cost savings of using pyuria alone as the sole criterion for omitting urine cultures. If in this study urine cultures had been performed only on specimens from children who had pyuria or were managed presumptively with antibiotics, cultures of 2600 (61%) specimens would have been avoided. Twenty-two of 212 patients with positive urine cultures would not have been identified initially. However, based on interpretation of acute phase reactants, initial 99Tc-dimercaptosuccinic acid scan results, response to management and incidence of renal scarring 6 months later, 14 of the 22 patients most likely had asymptomatic bacteriuria and fever from another cause. The remaining 8 patients probably had early urinary tract infection. CONCLUSIONS: The analysis of urine samples obtained by catheter for the presence of significant pyuria (> or = 10 white blood cells/mm3) can be used to guide decisions regarding the need for urine culture in young febrile children.

Bacteriological Techniques↗
PubMed1995

Changes in topoisomerase I levels and localization during myeloid maturation in vitro and in vivo.

Changes in topoisomerase I (topo I) levels and localization were examined during the course of granulocytic maturation in vitro and in vivo. Western blotting revealed that granulocytic maturation in DMSO-treated HL-60 human leukemia cells was accompanied by a 5-fold decrease in topo I polypeptide content. Consistent with this result, 3- to 5-fold higher concentrations of the topo I poison camptothecin were required to stabilize topo I-DNA adducts in DMSO-treated HL-60 cells compared to untreated cells. Northern blotting revealed that these changes occurred without any decrease in topo I message. Immunolocalization studies revealed that these quantitative changes were accompanied by redistribution of topo I away from the nucleoli, where it was prominently accumulated in untreated HL-60 cells, to a more uniform nuclear distribution in DMSO-treated cells. Similar changes occurred during granulocytic maturation in human marrow in vivo. Western blotting revealed that topo I levels in normal progranulocytes were 50% as high as those in HL-60 cells, levels in metamyelocytes were 35% as high as HL-60 cells, and levels in peripheral blood granulocytes were 5% as high as HL-60 cells. Two other polypeptides that are concentrated in nucleoli, poly(ADP-ribose) polymerase and B23/nucleophosmin, also decreased during the course of granulocytic maturation. These changes were accompanied by an alteration in topo I localization similar to that observed in HL-60 cells during the course of granulocytic maturation. Conversely, treatment of human lymphocytes with the mitogenic lectin concanavalin A resulted in a 3-fold increase in topo I polypeptide content concomitant with a prominent increase in the amount of nucleolar antigen. These observations not only provide a context for understanding the recent observation that topo I levels are higher in human leukemia specimens than in normal marrow but also raise the possibility that elevated topo I levels in other cells might reflect alterations in nucleolar structure and function.

Cell Nucleus↗