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Biomedical subjects

J Ritter

Publications and source records attributed to J Ritter.

At least 91 records · Page 5Linked to original sources
PubMed1998

Flow cytometric identification of candidate normal stem cell populations in CD45-negative B-cell precursor acute lymphoblastic leukaemia.

CD45-negative B-cell precursor acute lymphoblastic leukaemia (ALL) provides a unique model to study the stem cell compartment in ALL as leukaemic CD34-positive cells, unlike their normal counterparts, do not express CD45. By increasing the number of events analysed to 10(6), storing only the events in the region of interest (storage gate), using appropriate isotype controls and stringent washing procedures, a flow cytometric protocol was established to characterize rare CD34+ CD19- events. In eight of 12 patients (67%) with CD45-negative B-cell precursor ALL, a distinct CD34+ CD19- CD45+ candidate normal stem cell population could be detected. In one patient analysed by four-colour staining, the CD34+ CD19- CD45+ cells, unlike the CD45-negative leukaemic cells, expressed CD117 (c-kit), providing further evidence that these cells represent residual nonleukaemic normal cells. By multiparameter analysis, this population of candidate normal stem cells could be separated from contaminating leukaemic CD34+ CD19- CD45- cells, which were detected in 11 of the 12 patients within the CD34+ CD19- compartment.

Acute Disease↗
PubMed1998

Utility of transbronchial biopsy in patients with acute respiratory failure: a postmortem study.

STUDY OBJECTIVE: To determine the diagnostic yield of histologic specimens obtained by postmortem transbronchial biopsy (TBB) in patients with acute respiratory failure requiring mechanical ventilation. DESIGN: Standard postmortem histologic examination of lung tissue specimens. SETTING: An urban university-affiliated hospital. PATIENTS OR PARTICIPANTS: Thirty patients with diffuse pulmonary infiltrates and acute respiratory failure, who underwent postmortem examination. INTERVENTIONS: Following removal of the lungs from the thorax. TBBs were obtained from the lower lobe of each deflated lung and comparison was made to a 1-cm3 tissue block obtained from the ipsilateral lower lobe. MEASUREMENTS AND RESULTS: Standard postmortem histologic examination provided a specific diagnosis in 85% of the 60 lungs examined, and histologic evidence of acute pneumonia was present in 30% of the lungs. The overall yield of TBB was 48% for establishing a specific histologic diagnosis and 15% for the diagnosis of acute pneumonia. Using standard postmortem histologic examination as the gold standard, the sensitivity and specificity of TBB for making a specific diagnosis were 57% and 100% respectively, with corresponding positive and negative predictive values of 100% and 29%. For the histologic diagnosis of acute pneumonia, the sensitivity of TBB was 50%, the specificity was 100%, and the positive and negative predictive values were 100% and 82%, respectively. The kappa statistic for the agreement between the two diagnostic methods was 0.28 for establishing a specific diagnosis and 0.58 for the diagnosis of acute pneumonia. Obtaining 12 TBBs rather than six TBBs did not increase the diagnostic yield for TBB. CONCLUSIONS: These findings suggest poor overall agreement between standard postmortem histologic examination and TBB specimens. Although not performed in a clinical setting, this postmortem investigation suggests that TBB may be of limited value in mechanically ventilated patients with acute respiratory failure because of its low sensitivity.

Acute Disease↗
PubMed1998

[Therapy of febrile neutropenia episodes in systemic hematologic illnesses with new once daily ceftriaxone administration].

In this open label prospective multicenter trial, 420 patients with neutropenia < 1000/microliter, fever > 38.5 degrees C and hematological malignancies were treated with ceftriaxone. Acute leukemia (n = 238) and high-grade lymphoma patients (n = 182) from 35 centers were enrolled. Between February 1992 and January 1996, patients were treated with 2 g ceftriaxone i.v. per day either as monotherapy (n = 135), or in combination with aminoglycosides (n = 235), glycopeptides (n = 37), or other antimicrobial agents (n = 13). Patients' median age was 54 years (range 15 to 97) with a median Karnofsky-performance-score of 6.0. The median neutrophil counts were 400/microliter. Fever was of unknown origin (FUO) in 268 (63.8%) of patients. Clinically defined infections (CDI) were diagnosed in 152 (36.2%) cases, including 74 (17.8%) episodes with pneumonia. Response to the initial approach with ceftriaxone was observed in 56.2% of febrile episodes, including 93 (68.8%) treatment courses with ceftriaxone alone. Concerning defervescence of fever ceftriaxone monotherapy was successful as compared to ceftriaxone in combination. Analysis revealed a low risk characterized by higher neutrophil counts (> or = 500/microliter; p < 0.0001), better Karnofsky-performance-score (> or = 7; p = 0.01), duration of neutropenia (< or = 5 days; p = 0.008) from start of antimicrobial treatment and duration of neutropenia per cycle (< or = 10 days; p = 0.0016). At the end of the observation, an overall response was obtained in 88.3% of the patients (n = 371) without statistical difference between patients treated with ceftriaxone alone or in combination. Once daily ceftriaxone either alone or in combination was effective in patients with hematological malignancies. Monotherapy was effective in a low risk group characterized by neutrophil counts (> or = 500/microliter), a Karnofsky-performance-score (> or = 7) and a duration of neutropenia (< or = 5 days) at the commencement of treatment.

Acute Disease↗
PubMed1998

[Color Doppler in the prenatal diagnosis of umbilical cord hernia].

Pathologies of the fetal ventral abdominal wall are easily diagnosed by antenatal ultrasonography. The most common anomalies are omphalocele, often associated with other malformations or chromosomal abnormalities, and gastroschisis. We describe an antenatal diagnosis of umbilical cord hernia which could be confirmed by color Doppler. This entity is important to know not to put the umbilical clamp on a bowel loop after delivery.

Adult↗
PubMed1997

A novel type of thermostable alpha-D-glucosidase from Thermoanaerobacter thermohydrosulfuricus exhibiting maltodextrinohydrolase activity.

An alpha-glucosidase with the ability to attack polymeric substrates was purified to homogeneity from culture supernatants of Thermoanaerobacter thermohydrosulfuricus DSM 567. The enzyme is apparently a glycoprotein with a molecular mass of 160 kDa. Maximal activity is observed between pH5 and 7 at 75 degrees C. The alpha-glucosidase is active towards p-nitrophenyl-alpha-D-glucoside, maltose, malto-oligosaccharides, starch and pullulan. Highest activity is displayed towards the disaccharide maltose. In addition to glucose, maltohexaose and maltoheptaose can be detected as the initial products of starch hydrolysis. After short incubations of pullulan, glucose is found as the only product. At high substrate concentrations, maltose and malto-oligosaccharide, but not glucose, are used as acceptors for glucosyl-transfer. These findings indicate that the T. thermohydrosulfuricus enzyme represents a novel type of alpha-glucosidase exhibiting maltase, glucohydrolase and 'maltodextrinohydrolase' activity.

Amino Acid Sequence↗
PubMed1997

The pregnant ewe: an animal model for fetoscopic surgery.

OBJECTIVE: To develop an animal model for fetal endoscopic surgery which could be feasible and reproducible. The aim of this work was to perform a fetoscopy without the need of a laparotomy. METHODS: Pregnant ewes underwent under general anesthesia laparoscopy with the creation of a maternal pneumoperitoneum. After localizing the placenta by transillumination, we carried out fetoscopy through a 5 mm trocar using a perfusion of Ringer's solution. RESULTS: Five video-assisted procedures have been performed. None of the cases has shown any bleeding from myometrial wounds and no suture was necessary. There was no leakage of amniotic fluid. Intrauterine space was large enough to manipulate instruments without producing any fetal damage. Sharp visualization and anatomical description of the fetus were precise without the use CO2. There were no miscarriages and postnatal examinations of the lambs were normal. CONCLUSION: Fetoscopic surgery can be performed in the pregnant sheep without any complications but preterm labor which is the main problem in human fetal surgery, is infrequent in the sheep. Our model is reproducible and simulates the surgical endoscopic procedures which will occur in a close future in the human species.

Animals↗
PubMed1997

Development of a reverse transcriptase PCR-enzyme-linked immunosorbent assay for quantification of human immunodeficiency virus type 1 RNA in plasma: comparison with commercial quantitative assays.

A quantitative reverse transcriptase PCR assay with automated detection by nonradioactive hybridization was developed for the determination of human immunodeficiency virus (HIV) type 1 RNA levels. This assay is based on the use of an external standard curve with an internal standard. The accuracy of quantification was verified by comparison with reference commercial tests, the Chiron branched-DNA and Roche AMPLICOR HIV MONITOR assays. This assay was able to quantify viremia in patients with CD4 cell numbers below and above 500/mm3 and to quantify some HIV strains which could not be titrated by the MONITOR assay.

DNA Primers↗
PubMed1997

Low risk of secondary leukemias after chemotherapy without mechlorethamine in childhood Hodgkin's disease. German-Austrian Pediatric Hodgkin's Disease Group.

BACKGROUND: In the last two decades, it has become evident that secondary leukemias after Hodgkin's disease (HD) are mainly caused by the treatment with alkylating agents, especially mechlorethamine. Since 1978, the German-Austrian trials for childhood HD have used combined chemoradiotherapy without mechlorethamine. PATIENTS AND METHODS: The risk of secondary hematologic malignancies (SHM) was assessed in the total cohort of 667 children treated in four consecutive German-Austrian trials between 1978 and 1990. Primary chemotherapy for stages IA/B and IIA consisted of two cycles of vincristine, procarbazine, prednisone, and doxorubicin (OPPA) or OPA (without procarbazine) and, for more advanced stages, of two cycles of OPPA or OPA plus two, four, or six cycles of COPP or COMP (C, cyclophosphamide; M, methotrexate). Radiotherapy was given in the first study to extended fields, and in later trials to involved fields only. In 591 patients, only primary therapy was given; 76 patients (11%) needed additional salvage therapy. The actuarial survival rate at 15 years is 94%. RESULTS: SHM developed in 5 of 667 patients: four acute myeloid leukemias (AMLs) and one myelodysplastic syndrome (MDS). The estimated cumulative risk for SHM at 15 years is 1.1% (95% CI, 0.0% to 2.2%). Salvage therapy was a significant risk factor for SHM (relative risk, 7.25; P = .03), whereas age, sex, stage of HD, splenectomy, and amount of alkylating agents were not. CONCLUSION: The observed risk of SHM is smaller than in other studies (adults and children) in which chemotherapy with mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) was given. This difference can be attributed to the lower cumulative doses of alkylating agents, the absence of mechlorethamine in the chemotherapy, and the small number of patients who needed salvage therapy in the presented cohort. In general, differences in the incidence of SHM after HD reflect complex differences between treatment strategies.

Adolescent↗
PubMed1997

An analysis of the factors involved in the diagnostic accuracy of colposcopically directed biopsy.

OBJECTIVE: To compare the results of colposcopically directed biopsy with the final diagnosis established by the analysis of the surgical specimen, and to determine the clinical and colposcopic factors on which the reliability of biopsy is based. MATERIAL AND METHODS: Five hundred and sixty-seven women were seen by the same colposcopist who also performed the directed biopsies and/or the endocervical curettage. The final histological diagnosis identified 29 normal aspects (5.2%), 58 low-grade cervical intraepithelial neoplasias (CIN) (10.2%), 448 high-grade CINs (79.0%), 16 microinvasive cancers (2.8%) and 16 occult invasive cancers (2.8%). The influence of several factors--such as age, parity, menopause, pregnancy, history of cervical treatment, site of the squamocolumnar junction, localization, size and severity of the lesions--on the pertinence of the biopsy was studied in a uni- and multifactorial analysis. RESULTS: Colposcopy was satisfactory in 399 patients (70.4%) in whom the colposcopic aspect was consistent with the final histological diagnosis in 81.2% of cases. The global agreement between biopsy diagnosis and final diagnosis was observed in 89.6% of cases. It was 84.2% for low-grade CINs, 95.8% for high-grade CINs, 31.2% for microinvasive cancers and 81.2% for invasive cancers. No clinical or colposcopic factor could be identified as independent factor associated with the diagnostic agreement with the directed biopsy. Conversely, concordance of biopsy was related to the final diagnosis since the only independent risk factors were a high-grade CIN (adjusted risk ratio (ARR)=1.52, 95% CI=1.11-2.08; p=0.006) and a microinvasive or invasive cancer (ARR=0.56, 95% CI=0.39 0.81; p=0.002). CONCLUSION: To ensure that a microinvasive cancer has not been overlooked, the excision of high-grade CINs seems to be justified, whatever the clinical status and the colposcopic aspect.

Adolescent↗
PubMed1997

[Consequences and treatment of cervical stenoses after laser conization or loop electrosurgical excision].

OBJECTIVE: To assess the frequency and the consequences of cervical stenosis in patients treated by laser conization or loop electrosurgical excision procedure (LEEP) and to analyse the results of cervical enlargement plastic surgery or neostomia. METHODS: Two hundred and fifty-five women treated by laser conization and 277 by LEEP were regularly followed by postoperative colposcopy, for a mean period of 38 and 16 months, respectively. Stenosis was defined as cervical narrowing which could not admit a 2.5 mm-diameter Hegar's dilator. RESULTS: Stenosis complicated 10.2% of the laser conizations and 4.3% of the LEEP. Thus, 38 cases of cervical stenosis of which 7 were complete were diagnosed 2 to 40 months after treatment. Among the 34 non-menopaused women who developed a stenosis, 5 had a secondary amenorrhea, 6 a severe dysmenorrhea and one an infertility related to oligoamucorrhea. In the patients with stenosis, endocervical cell retrieval was possible in 21 (55%) cases and in none the squamocolumnar junction was visible at colposcopy. Seven patients underwent an enlargement plastic surgery of the cervical canal for incomplete stenosis and two a neostomia for complete stenosis. Cervical restenosis has been observed in 7 of 9 cases in a mean delay of 12 months (3 to 48 months). Nevertheless, the endocervical cell retrieval remained possible in 8 of 9 cases and after a mean follow-up of 26 months no menstrual troubles recurred. CONCLUSION: LEEP provides fewer cervical stenosis than laser conization. The enlargement plastic surgery allows to correct durably the menstrual troubles in spite of the very frequent restenosis.

Adult↗
PubMed1997

[HELLP syndrome. Review and update].

Whether HELLP syndrome is a distinct entity or a severe form of preeclampsia, it remains a factor of gravity. Described by Weinstein in 1982, it associates hemolysis, cytolysis (elevated liver enzymes) and thrombopenia (low platelets). The cut off for the biological parameters have to be strictly defined to avoid overdiagnosis of HELLP syndrome. The difficulty to diagnose this syndrome is real because most of the associated clinical signs are aspecific. The errors of diagnosis are more frequent when the syndrome is not associated to preeclampsia (10%), in the mid-trimester (15%) and in the postpartum (30%). The mean term of delivery is 32 weeks, the prematurity being widely induced because of the fear of maternal complications. Maternal deaths (1.1%) do not seem to be directly related to the HELLP syndrome. Subcapsular hematomas of the liver are unfrequent (0.9%). Rapid termination of pregnancy, by vaginal delivery or by cesarean, is generally recommended when the fetal lung maturity is obtained or when maternal complications appear. Conversely, conservative management is acceptable before 32 weeks. Corticosteroid therapy or hemodynamic therapy could allow to obtain fetal lung maturity. A conservative approach requires permanent materno-fetal follow-up which can only be achieved in a perinatal center integrating a neonatal intensive care unit.

Adrenal Cortex Hormones↗
PubMed1997

[Non-invasive lesions of the cervical glands. Apropos of a study of 431 conization specimens].

431 cone biopsy specimens referred for CIN2 and CIN3 between 1984 and 1993 were reviewed with a peculiar attention paid to the possible associated endocervical glandular changes. The following features could be demonstrated: microglandular hyperplasia (17 cases), tubal metaplasia (15 cases), mesonephric hyperplasia (10 cases), in situ adenocarcinoma (7 cases), tunnel clusters (5 cases), and ectopic endometrium (4 cases). Cervical glandular atypia could not be found. A classification of the glandular lesions in uterine cervix has been proposed for an accurate diagnostic approach of lesions who could simulate carcinomatous changes.

Adenocarcinoma↗
PubMed1997

Orthotopic heart transplantation in a child with heterotaxia syndrome: a case report.

We report a case of a successful orthotopic heart transplantation in a seven year old boy with heterotaxia syndrome, d-transposition of the great arteries, rudimentary right ventricle, double inlet left ventricle, valvular pulmonary stenosis, left-sided peripheral pulmonary artery stenosis, deficient atrial septation, and left-sided superior and inferior vena cava. In this case of congenital heart defects, three specific surgical procedures were necessary to make heart transplantation feasible. A synthetic patch was interposed in the single atrium to create two separate atria. To handle the mismatch of the donor's and recipient's aortic diameters, the donor's aortic diameter was enlarged by including the aortic arch into the anastomosis. The left-sided superior vena cava was led to the right appendage by interposing a piece of autogenous aorta.

Anastomosis, Surgical↗
PubMed1997

[Occurrence of Echinococcus multilocularis Leuckart, 1863, in foxes (Vulpes vulpes) in the Czech Republic].

During the period between December 1994 and December 1996 the authors examined, using the method of helminthological dissection of the intestinal tract in 15 districts of four regions in the Czech Republic a total of 824 foxes from 350 land registers. Echinococcus multilocularis was found in the following regions: South Bohemian (districts Jindrichův Hradec, Ceský Krumlov, Prachatice and Strakonice), Central Bohemian (Benesov district) and North Bohemian (district Teplice and Chomutov). There were 87 positive (10.6%) foxes in 56 places (16%). In some areas of the South Bohemian region examinations of foxes were repeated. It was found that there are places where the prevalence of E. multilocularis varied between 28.6 and 75% (mean 53.7%) but also areas which were repeatedly negative. In 1996 after one-week intervals foxes from the Prachatice district (South Bohemian region) were sent for parasitological examination. During different months of the year the prevalence of E. multilocularis varied between 2.6 and 33.3%. A similar investigation was made during May to October 1996 (except September) also in the district of Ceský Krumlov (South Bohemian region). Tapeworms were found in 7.14 to 66.7% of foxes.

Animals↗
PubMed1996

Intracellular retention of cytosine arabinoside triphosphate in blast cells from children with acute myelogenous and lymphoblastic leukemia.

The importance of the cellular pharmacokinetics of cytarabine triphosphate (ara-CTP) with regard to therapeutic efficacy is well established. In vitro and in vivo monitoring of pharmacokinetic parameters of leukemic blast cells were initiated in order to contribute to the pharmacological basis of optimal ara-C treatment strategies. Peripheral or bone marrow blast cells from 66 leukemic patients [51 acute myelogenous leukemia (ALL), 15 acute lymphoblastic leukemia (AML) were separated and incubated with ara-C for 1 hour and in ara-C-free medium for another 3 hours, and the intracellular formation and retention of ara-CTP was measured. In eight children who received continuous ara-C infusion for induction treatment, the ara-CTP concentration in circulating blast cells was monitored in vivo. The in vitro values observed in this assay corresponded to the cellular levels monitored in vivo. The ara-CTP retention differed clearly among the individual groups, as classified by immunophenotype at the time of the initial diagnosis: non-T-ALL 67+/-25% (x+/-SD, n=33), T-ALL 37+/-15% (n=8), and AML 34+/-18% (n=14). The difference in ara-CTP retention between non-T-All and AML (P<0.05) as well as T-ALL (P<0.05) was significant. There was a tendency toward lower ara-CTP retention in relapsed as compared with newly diagnosed ALL, but the difference was not significant. The maximal accumulation of ara-CTP (after 1 hour incubation) was comparable in AML, T-ALL, non-T-ALL, and blast cells from children in relapse. The observed similarity of cellular accumulation in all groups and the significantly more rapid decrease in T-ALL and AML provide the pharmacokinetic rationale supporting the prolonged infusion duration for ara-C in these subgroups as an alternative to the intensification by high-dose ara-C schedules with short-term infusion.

Adolescent↗
PubMed1996

In vivo 31P NMR spectroscopy of human musculoskeletal tumors as a measure of response to chemotherapy.

The value of in vivo 31P NMR spectroscopy to provide indicators of response to cytostatic chemotherapy was studied in patients with malignant musculoskeletal tumors. Characteristics of untreated cancers were strong signals of PME and PDE, moderately increased Pi and low PCr. The intracellular pH was slightly alkaline. The intracellular concentration of free magnesium was 70% of that in muscle. Spectroscopic findings at different times of therapy were compared with the percentage of tumor necrosis after surgical resection in 28 patients. In follow-up studies, energy-rich phosphates declined in nonresponders, while PME, Pi and frequently PDE increased. Treatment response appeared to involve the reversal of these trends. In five responders, a biphasic pattern was observed, i.e. initially the spectrum changed into that of severely ischemic cell injury followed by a successive phase of apparent 'tumor activation'. Pretreatment levels of (PCr+Pi)/total phosphate > or = 0.35 and PCr/ alpha-NTP > or = 1.5, an accelerated increase in total low-energy phosphates/total high-energy phosphates (> or = 3.0%/day) after the initial drug application, and a long-term decrease (< or = -0.4%/day) during later therapy were highly indicative of tumor response to chemotherapy. Such spectroscopic predictors for treatment response proved to be superior to currently used indices such as tumor size.

Adolescent↗