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At least 829 records · Page 46Linked to original sources

PubMed1994

Apoptosis induced by DNA topoisomerase I and II inhibitors in human leukemic HL-60 cells.

The induction of apoptosis following topoisomerase inhibitors proceeds in at least three distinct steps: (1) induction of cleavable complexes (potentially lethal damage), (2) topoisomerase-induced DNA damage, and (3) a presently unknown sequence of events that must either lead to cell cycle arrest (G2-block, differentiation) or apoptosis. DNA degradation provides a convenient way to quantify apoptosis in HL-60 cells. Extensive apoptosis can be induced rapidly in undifferentiated HL-60 cells without prevention by cycloheximide or actinomycin D. Therefore, HL-60 cells appear to express constitutively the apoptotic machinery that may be kept under control of a yet unknown repressor. The absence of the tumor suppressor p53 and the presence of bcl-2 are in contrast with the sensitivity of these cells to apoptosis. Agents that modify chromatin structure (zinc, poly[ADPribose] inhibitors, spermine) can block DNA fragmentation without affecting cell survival. By contrast macrophage-like differentiation by phorbol esters suppresses apoptosis without affecting topoisomerase-induced DNA damage. Better understanding of the apoptotic regulation in the widely used and characterized HL-60 cell line should allow the identification of new mechanisms and parameters of cellular sensitivity and resistance to the cytotoxic activity of anticancer agents.

Antineoplastic Agents↗

PubMedDate not supplied

Relationship between pharmacokinetics of 5-FU in plasma and in saliva, and toxicity of 5-fluorouracil/folinic acid.

BACKGROUND: Dose adaptation based on pharmacokinetic parameters has been shown to decrease toxicity of some 5-fluorouracil(5-FU)-based continuous infusion regimens. PATIENTS AND METHODS: In the present study the relationship between 5-FU pharmacokinetics in plasma and in saliva, and toxicity was investigated in 40 patients receiving the combination of 5-FU 425 mg/m2 and folinic acid 20 mg/m2 daily during 5 consecutive days according to the Mayo-regimen. RESULTS: The overall non-hematological and hematological toxicity, as well as mucositis only, were not statistically significant related to the area-under-the-curve in plasma (AUCp) or in saliva (AUCs), nor to the maximum concentration measured in plasma (Cmaxp) or in saliva (Cmaxs). Although statistically significant, the correlation between the AUCp and AUCs was relatively low, implying that salivary pharmacokinetics are not accurately predictive of plasma pharmacokinetics. CONCLUSION: The conclusion of this study is that the application of pharmacokinetic parameters is not appropriate for identification of patients at risk for developing toxicity from treatment with 5-FU according to the Mayo-regimen.

Adult↗

PubMed2004

Combination of gas chromatography-mass spectrometry and mass spectral deconvolution for structural elucidation of an unusual C29-steroid detected in a complex sedimentary matrix.

A complex sedimentary sample from the Monterey Formation (CA, USA) has been submitted to GC-MS analysis followed by mass spectral deconvolution using Automated Mass Spectral Deconvolution and Identification System (AMDIS). Adjusting the parameters of the software allowed for the extraction of the spectrum of an unusual steroidal hydrocarbon coeluting with the major compound of the chromatogram. Following a careful interpretation of the "extracted" mass spectrum, the structure of the unknown has been postulated to be the 4,14-dimethylcholestane (DMC). Possible origins of this rare steroid are briefly discussed. Thus, application of AMDIS appears to be particularly suitable for the GC-MS analysis of natural complex mixtures characterized by a high number of analytes present in low amounts.

Cholestanes↗

PubMed1998

[Analysis of air pollutants with a combination of GC/FTIR and GC/MS].

In this paper, the air pollutants were analyzed with a combination of Gas chromatography/Fourier transform infrared spectroscopy (GC/FTIR) and Gas chromatography/Mass spectroscopy (GC/MS). The organic mixture was well separated after a careful adjustment of GC and IR parameters in GC/FTIR. In the identification of unknown components, MS is a main method, while IR is also useful to confirm the results.

English Abstract↗

PubMed2005

Clinical evaluation of a panel of mRNA markers in the detection of disseminated tumor cells in patients with operable breast cancer.

Persistent high mortality rates in breast cancer patients, in spite of latest advances in diagnosis and therapy, affirm the necessity of new developments in tumor biology prognostic factors. Immunocytochemical detection of disseminated breast cancer cells in bone marrow has been frequently associated with a decrease in disease-free survival as an independent prognostic factor, but methods based on molecular biology procedures must still be validated. Considering tumor heterogeneity, the multimarker approach has been suggested as a better strategy than individual marker assays. The aim of this work was evaluation of the prognostic value of a multimarker reverse-transcriptase polymerase chain reaction (RT-PCR) assay, associating four mRNA markers for the detection of disseminated breast cancer cells. We compared the prognostic significance of cytokeratin 19 (CK19), carcinoembryonic antigen (CEA), mammaglobin (MG) and the mucin MUC5B mRNA in bone marrow aspirates in the follow-up of 80 operable breast cancer patients. The best prognostic value for clinical outcome was seen for CEA mRNA, not improved for any association with other markers. Unexpectedly, some tumor mRNA in bone marrow correlates with a favorable clinical outcome, especially MUC5B. Therefore, our results suggest that not all epithelial or tumor markers have the same significance in predicting the metastatic potential of disseminated cancer cells. New parameters are needed for the identification of individual patients at high risk of tumor recurrence. Multimarker RT-PCR assays could be a good approach, but they should be performed associating mRNA markers that are able to predict tumor aggressiveness associated with poor outcome and not just epithelial markers, which only indicate the mere presence of tumor cells.

Adult↗

PubMedDate not supplied

[Problems of structural and functional identification of biological tissues].

The theoretical methods of identification of topological and functional parameters for biological tissues, such as myocardium, are considered. Among the unknown topological parameters are the dimension and connectivity of a network, and the unknown functional parameters include the electrical resistance of the cellular membrane and cytoplasm. Experimentally known data are the sizes of cells (length and diameter), the input resistance of tissue, and also the field of electrical potential formed by a "dot" current source (by an intracellular microelectrode).

Electrophysiology↗

PubMed1990

[Acute gastroenteritis: a prospective study of 445 cases].

Four hundred and fourty-five adult patients suffering acute gastroenteritis (AG) seen at the emergency ward of two hospitals in Barcelona, have been studied. The aim of this work was to analyze the cause of AG in our community and to evaluate the utility of the biologic and clinical criteria chosen as indicators of bacteremia or of AG produced by invasive microorganisms. Stool culture was positive in 157 patients (35%) of which 140 were Salmonella sp. The most frequently isolated serotype was S. enteritidis. Eight patients (7.8%) presented Salmonella sp. bacteremia. Presence of an underlying disease, dehydration, shivers, fever, presence of occult blood in stools, septic hemogram and the history of AG in other family members were more common in patients with a positive stool culture (p less than 0.05). Patients with bacteremia presented dehydration with a significantly higher frequency than nonbacteremics. The rest of the parameters studied were similar in both groups. We conclude that Salmonella sp. is the most frequently encountered microorganisms responsible for adult AG in our community. It is possible to identify patients with AG due to Salmonella sp. based on clinical and biological parameters. On the contrary, it is necessary to perform a wider study in order to determine the parameters that may allow the identification of patients with bacteremia.

Acute Disease↗

PubMedDate not supplied

[Sclerotherapy of esophageal varices].

The first published report on sclerotherapy of esophageal varices appeared 50 years ago, but it is during the last decade that its use has generalized. The indications, technique, site of injection and type of substance used have changed in the last years. At the present time it is accepted that it is effective for the control of acute bleeding from variceal rupture and it is probably the procedure of choice in this situation. The present tendency is to continue to sclerosis after the acute bleeding. Sclerotherapy of patients that have never bled is still controversial, it is necessary to establish parameters that may permit the identification of patients with risk of bleeding in whom prophylactic sclerotherapy would be justified.

Esophageal and Gastric Varices↗

PubMed1989

[A-mode echography of frontal sinus aplasia].

Twenty-five patients with radiologically proven unilateral frontal sinuses were examined by A-mode ultrasound and the aplastic sinus was compared with the air-filled sinus on the other side. The number of echoes as well as the amplitude and time behaviour of each side were recorded. Statistical evaluation showed no difference in the sonographic parameters between the two sides. Identification of aplastic frontal sinuses by ultrasound is not possible.

Adolescent↗

PubMed1986

[Nuclei of lymphocytes of the T- and B-cell lines during normal embryogenesis and after treatment with hydrocortisone (morphometric and probabilistic-statistical parameters)].

Lymphoid cells of the thymus and of the Fabricius bursa have been studied in 18-day-old chick embryos, normal and after injection of hydrocortisone on the 11th day of embryogenesis. By means of optical-structural computer analysis, the complex of morphometric and probability-statistic parameters of the nuclei in the lymphocytes are estimated: area of the nuclei, optical density of chromatin, asymmetry coefficient and variance. Normal T-lymphocytes possess less density of the nuclei, greater optical density of chromatin, greater values of negative asymmetry. The complex of these parameters can be used for identification of visually similar lymphoid cells of T- and B-lines. Under hydrocortisone effect structural changes of the nuclei in the thymus and Fabricius bursa lymphocytes of the chick embryo are uniform: increase in the area of the nuclei, decrease in optical density of chromatin, the asymmetry coefficient becomes positive.

Animals↗

PubMed1982

Family practice as a specialty choice: effect of premedical and medical education.

Identification of beneficial and detrimental parameters influencing the choice of family practice as a career was the object of the study reported here. Curriculum components and elements during or before medical school were examined. A questionnaire listing 18 factors that influenced specialty choice before residency training was completed by 134 first-year family practice residents. Participation in a family practice clerkship or preceptorship during the third and fourth years of medical school and association with family physicians during or before medical school were perceived as most beneficial. Generally, students' experiences during the first three years were perceived as detrimental to selecting family practice. Also, data indicated that 75 percent of the students select their specialty during years three and four. Medical schools wishing to increase the number of their graduates entering family practice should strongly consider requiring clinical rotations in family medicine and providing maximum exposure to family practice residents and faculty members as role models.

Career Choice↗

PubMed1995

[New parameters for prediction of pathological stage in clinical stage I non-seminomatous testicular tumors].

Traditional histopathological risk factors have failed to predict pathological stage accurately in clinical stage I nonseminomatous testicular germ cell tumours. Histopathology, flow cytometry, cytophotometry, and immunohistochemical staining techniques were used in an effort to define high- and low-risk groups for occult metastasis in a consecutive series of 105 patients who underwent retroperitoneal lymph node dissection. After multiple logistic regression analysis, the proliferative S + G2M cell cycle fraction of the aneuploid tumour stemline was the most highly predictive parameter of pathological stage (P = 0.0004). Using a cut-off of 41%, pathological stage II patients were predicted with a sensitivity of 71%. There were 61 patients with S + G2M values below 41%, and 43 of them had pathological stage I disease (negative predictive value 87%). A low volume of embryonal carcinoma was predominant in low-risk patients, and MIB-1 immunohistochemical staining identified a subgroup of 23% of patients with pathological stage I disease and at extremely low risk of metastatic disease. Assessment of tumour cell proliferation does not allow accurate classification of high-risk patients at a level that is adequate for clinical application. Patients who are at low risk of metastasis, however, can be identified by flow cytometry, immunohistochemical proliferation markers and volume of embryonal carcinoma with 90% certainty. These parameters deserve further study, since identification of a subgroup of patients at extremely low risk of metastasis could potentially reduce the overall morbidity in the management of clinical stage I nonseminomatous testis cancer.

Animals↗

PubMed1993

[Quantification of the intra-penile smooth muscle with a fuzzy logic algorithm].

We have developed a new computer program for tissue segmentation designed for the quantification of smooth muscle in the corpus cavernosum. The program uses digitalized images of stained histological sections taken with a CCD camera. The recognition of the different tissues is based on the examination of absorption of monochromatic light. The section is successively illuminated with light of three different wavelengths and the three absorption values and texture parameters are used for the identification of the tissue using a fuzzy algorithm.

Absorption↗

PubMed1994

[Satisfactory results of surgical reconstruction of rotator cuff ruptures, 1984-1990].

OBJECTIVE: Evaluation of the middle-long term results of open surgical treatment of rotator cuff tears and identification of pre- and peroperative parameters with predictive value for the final result. DESIGN: Retrospective study (1984-1990). SETTING: Department of orthopaedics of the Sint Antonius Hospital, Nieuwegein, the Netherlands. METHOD: All patients were asked to cooperate on an extensive standard anamnesis and physical examination. Re-evaluation of the X-rays, arthrograms and operation reports took place. There were three stragglers. RESULTS: The follow-up concerned 41 shoulders in 40 patients (21 women, 19 men). The average age was 61 years (37-77). The average postoperative period was 5 years (2.5-9.2). The subjective final result was satisfactory in 80% as judged by persistent complaints and function of the operated shoulder. Young and active patients were less satisfied with the final result than older, female patients. More persistent complaints were seen in larger and longer existing cuff tears. CONCLUSIONS: Open surgical treatment of rotator cuff tears gave a satisfying result, as described in literature. Sex, age, level of activity and size of the tear appeared to be predictive parameters for the subjective final result.

Adult↗

PubMed1997

Relationship between DNA ploidy and functional estrogen receptors in operable prostate cancer.

OBJECTIVE: To evaluate the relationship between the nuclear DNA content and the tissue estrogen receptor (ER) level in patients with operable adenocarcinoma of the prostate. METHOD: Surgical specimens taken from 73 patients with clinically localized prostate cancer were studied. Tumor DNA ploidy pattern as measured by flow cytometry was correlated with the level of functional ER using the nuclear biopsy assay. RESULTS: Forty-five percent of the tumors were DNA diploid, and 55% had an abnormal ploidy pattern (DNA tetraploid or DNA aneuploid). The ER level ranged from 0 to 6,475 fmol/mg DNA (mean 839 fmol/mg DNA). Twenty-two percent had no functional receptors. Marked association was noted between ER and nuclear DNA content. Seventy-five percent of the tumors with no ER had abnormal ploidy patterns. The mean receptor level for DNA diploid prostate cancer was 1,034 fmol/mg DNA versus 661 fmol/mg DNA for DNA nondiploid tumors (p < 0.008). An inverse correlation was found between ER values and histologic grade or pathologic stage. High-grade and high-stage tumors had lower levels of ER compared to low-grade and early-stage carcinomas. CONCLUSION: Our results demonstrate an association between ER values and variables that predict prognosis in prostate cancer. It is possible that this parameter may be helpful in identification of prognostic groups in patients with prostate cancer.

Adenocarcinoma↗

PubMedDate not supplied

Preparation and evaluation of bacterial stocks for filter validation.

Bacterial cell stock paste of Brevundimonas diminuta (American Type Culture Collection # 19146) used for filter validation was evaluated by standard microbiological procedures to determine culture purity, monodispersion, cell size, and strain identity. Tests performed included direct microscopic count, standard plate count, gram stain, streak plate, sizing by microfiltration, scanning electron microscopy, and biochemical identification. Results indicated the bacterial stocks were of consistent quality in terms of bacteriological purity, cell size, viability, and concentration. Sizing by microfiltration confirmed consistent monodispersion and cell retention characteristics for each lot tested. Use of the commercially available RapID NF Plus system confirmed each lot to be B. diminuta as indicated by biochemical profile and identification database. These tests represent parameters necessary for qualification of bacterial stocks to be used for filter validation.

Bacteriological Techniques↗

PubMed1976

Estimating the rate constants in a two-compartment stochastic model.

A procedure is described for estimating the rate constants of a two-compartment stochastic model for which the covariance structure over time of the observations is known. The proposed estimation procedure, by incorporating the known (as a function of the parameters to be estimated) covariance structure of the observations, produces regular best asymptotically normal (RBAN) estimators for the parameters. In addition, the construction of approximate confidence intervals and regions for the parameters is made possible by identification of the asymptotic covariance matrix of the estimators. The explicit form of the inverse of the covariance matrix, which is required in the estimation procedure, is presented. The procedure is illustrated by application to real as well as simulated data, and a comparison is made to the widely used nonlinear least squares procedure, which does not account for correlations over time.

Biometry↗

PubMed1998

Model-based dialysis adequacy prediction by continuous dialysate urea monitoring.

A modeling approach for on-line estimation of urea kinetics from continuous measurement of urea concentration in the effluent dialysate stream (DUN) is presented. On-line identification of urea kinetics response parameters is used to predict and update dialysis adequacy during the treatment. Dialysis adequacy can be quantified in several ways, but its strict dependence on final urea concentration is a major fact. For this reason, a good predictive skill on the time course of DUN may enable better performances in the control of dialysis outcome by treatment parameters adjustment. A post-filter enzymatic sensor performs continuous measurement of DUN on patients undergoing standard haemodialysis. To get an early prediction of the end dialysis urea level, the solution of a variable volume double-pool (VVDP) model is used, whose parameters are identified at each time on the basis of the past DUN history Unlike the variable volume single-pool (VVSP) model, this enables a prompt and accurate estimation of the final DUN. In fact, after 75 min the estimates always differ by less than 10% from the values measured by the sensor at the end of the treatment. Moreover, values predicted by the model in the last hour always lie within 1% of measured final values. Real-time knowledge of an analytic expression for whole DUN time course also enables the accurate prediction of total removed urea, with no need of cumbersome dialysate collection techniques.

Aged↗