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D Becker

Publications and source records attributed to D Becker.

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

Genotype and phenotype of N-acetyltransferase 2 (NAT2) polymorphism in patients with contact allergy.

We investigated whether patients with contact allergy differed from non-contact-allergic, non-atopic controls with regard to genotype and phenotype of the polymorphic enzyme N-acetyltransferase 2 (NAT2). 55 contact-allergic patients recruited from the Information Network of Departments of Dermatology (IVDK) were compared to 85 controls from among local health care personnel. NAT2 activity was calculated from HPLC analysis of the ratio of the caffeine metabolites 5-acetylamino-6-formylamino-3-methyluracil (AFMU) and 1-methylxanthine (1MX) in the urine. NAT2 genotype was determined by polymerase chain reaction (PCR). A statistically significantly increased proportion of rapid acetylators was found in contact-allergic patients. This may have 2 possible implications: acetylation may enhance contact sensitization; or NAT2 status may be a genetic marker for contact sensitizability.

Acetylation↗
PubMed1998

Individualized insulin therapy in children and adolescents with type 1 diabetes.

The most important point about individualized therapy is to make it flexible to fit the needs of the patient. These needs are determined by age, pubertal status, treatment schedule, exercise, intelligence, education and socioeconomic status. In addition, major emphasis should be placed on the dietary needs, attitude and ability of the patient. Aspects of insulin regimens that can be adjusted include number of injections per day, timing of injections and the type of insulin used. Several factors that affect insulin action should also be considered, including the presence of insulin antibodies, the amount of subcutaneous fat, injection technique and muscular activity. Insulin pump therapy in childhood and adolescence may also be considered in certain cases. Controversial areas in childhood diabetes therapy include the number of daily injections, whether porcine insulin has any advantages, use of multiple doses of intermediate- and long-acting insulin, mixing regular insulin and short-acting insulin analogues, strategies to prevent hypoglycaemia and the importance of choice of injection sites in childhood.

Adolescent↗
PubMed1998

Islet cell autoimmunity in white and black children and adolescents with IDDM.

OBJECTIVE: To compare the frequency of islet cell antibodies (ICA) and antibodies to GAD65 and IA-2(ICA512) between black and white children and adolescents at the diagnosis of IDDM in a large consecutive series of cases from Children's Hospital of Pittsburgh. RESEARCH DESIGN AND METHODS: ICA and antibodies to GAD65 and IA-2 were measured in 437 white and black children and adolescents who were diagnosed with IDDM at < 19 years of age at Children's Hospital of Pittsburgh from January 1983 to December 1985, from January to December 1989, and from January 1996 to December 1997. RESULTS: The prevalence of ICA(H), GAD65, and IA-2 antibodies was significantly lower in blacks than whites at onset of the disease. In contrast, the prevalence of ICA(R) alone was higher in blacks. None of the antibodies were present in 12% of the blacks compared with 4% in whites. The same pattern was seen in both sexes. The prevalence of antibodies in white patients with onset of IDDM at <11 years of age was no different than in those who developed IDDM during adolescence. In contrast, black patients showed a significantly lower prevalence of almost all antibodies in the adolescent group. CONCLUSIONS: Black adolescents were more likely to not have antibodies, suggesting either that they have a nonautoimmune type of diabetes or that antibodies are not being detected by these assays.

Adolescent↗
PubMed1998

Was there an epidemic of diabetes in nonwhite adolescents in Allegheny County, Pennsylvania?

OBJECTIVE: To determine the incidence of IDDM in children aged < 20 years at diagnosis in Allegheny County, Pennsylvania, for the period from 1 January 1990 to 31 December 1994 and to compare the incidence between whites and nonwhites in the same area and for the same time period. RESEARCH DESIGN AND METHODS: All new patients diagnosed between January 1990 and December 1994 who were aged < 20 years, on insulin, and residents of Allegheny County at diagnosis were identified from medical records of 23 hospitals in the Allegheny County area. To verify the completeness of the hospitals using the capture-recapture method, pediatricians and diabetologists were used as a secondary source. RESULTS: A total number of 257 patients were identified. The overall age-standardized incidence rate was 16.7/100,000. Nonwhites had a slightly higher incidence (17.6/100,000) than whites (16.5/100,000). In the 15-19 years age-group, the incidence in nonwhites (30.4/100,000) was almost three times higher than that in white (11.2/100,000) and more than two times higher than that in the previous period (from 1985 to 1989) (13.8/100,000). CONCLUSIONS: For the first time in the Allegheny County registry, and in any other registry, nonwhites showed a higher incidence of IDDM than whites. The high incidence in the 15-19 years age-group was responsible for this phenomenon. This epidemic of diabetes in adolescent nonwhites may be the result of a rising incidence of classical IDDM or another type of diabetes. Further studies using population-based registries are needed to determine whether this increase is being seen in other areas and other ethnic groups and to clarify the reasons for the increase in IDDM among blacks.

Adolescent↗
PubMed1998

TGF-beta and its receptor complex in leukemic B-cell precursors.

Transforming growth factor beta (TGF-beta) is a highly conserved peptide with growth-inhibitory activity in multiple normal and transformed cell types. Signal transduction is mediated through the receptor complex, consisting of two active seronine or threonine kinases (TGF-beta-receptor I and II) and the receptor-associated proteins betaglycan (TGF-beta-receptor III) and endoglin. In this study, we assessed the analysis of the role of TGF-beta and the transcription of the genes for TGF-beta and its receptor in highly purified leukemic B-cell precursors (BCPs) of patients with common acute lymphoblastic leukemia (cALL). Leukemic BCPs were positive for gene transcription of TGF-beta (9/9), the TGF-beta-receptor I (9/9), the TGF-beta-receptor II (6/6), betaglycan (5/6), and endoglin (6/6). Incubation with TGF-beta significantly reduced the cell viability of leukemic BCPs by a mean of 45% (p = 0.0009). The reduction of cell viability was associated with the induction of apoptosis by a mean of 31%. TGF-beta caused significant suppression of the S phase (p = 0.002) and accumulation in the G0/G1 phase (p = 0.0005). It also reduced expression of the adhesion surface receptor CD18 and the Fas antigen CD95 from 58% to 40% and from 48% to 27%, respectively. The data indicate that TGF-beta is a negative growth signal in leukemic BCPs and point to an additional role of TGF-beta as an immunomodulatory cytokine, suggesting a complex role of TGF-beta in the leukemogenesis of cALL.

Adjuvants, Immunologic↗
PubMed1997

[Differential diagnosis of acute testicular pain using color-coded duplex ultrasonography: difference between testicular torsion and epididymitis].

OBJECTIVE: To assess retrospectively the accuracy of colour-coded duplex sonography (CCDS) in distinguishing testicular torsion from epididymitis as the cause of acute testicular pain. PATIENTS AND METHODS: The results of CCDS were analysed for all 81 patients (mean age 27.2 years [6 weeks to 60 years]), admitted between 1.1.1995 and 30.6.1996 with the diagnosis of acute testicular pain. Testicular torsion was diagnosed when CCDS failed to detect perfusion in one testis. Regular arterial and venous perfusion of both testes excluded torsion. Epididymitis was diagnosed when hyperperfusion of the epididymis was demonstrated by CCDS. RESULTS: 20 of 22 cases of torsion, subsequently diagnosed at surgery, had been correctly diagnosed by CCDS (sensitivity 90.9%, specificity 98.3%). 55 patients had epididymitis, confirmed by the clinical course and follow-up having excluded torsion. Other causes (trauma, tumour, inguinal hernia) were found in the remainder of patients. CONCLUSION: With a positive predictive value of 95.2% and a negative one of 96.6% CCDS is a highly suitable method for recognizing or excluding testicular torsion and thus clarifying the cause of acute testicular pain.

Acute Disease↗
PubMed1997

Two-component flavin-dependent pyrrole-2-carboxylate monooxygenase from Rhodococcus sp.

Pyrrole-2-carboxylate can serve as the sole source of carbon, nitrogen, and energy for a strain tentatively identified to belong to the genus Rhodococcus. An NADH-dependent oxygenase activity was detected in cell extracts that initiated the degradation of the substrate. During purification of the enzyme, this activity was separated into two protein components which were both purified to apparent homogeneity. A small monomeric 18.7-kDa protein designated as reductase, catalyzed in vitro the NADH and FAD-dependent reduction of cytochrome c and had an NADH-oxidase activity. The second component, a 54-kDa protein with a trimeric native structure had no enzymatic activity by itself, but exhibited a pyrrole-2-carboxylate-dependent oxygen consumption when it was complemented with the reductase component, FAD, and NADH. This indicated that the large protein referred to as oxygenase was responsible for the oxygen-dependent hydroxylation of the substrate. The rate of an uncoupled NADH oxidation without hydroxylation of the substrate was found to be strongly dependent on the molar ratio of both components. The uncoupling was nearly completely suppressed by a 5-7-fold molar excess of the oxygenase component. The small protein was N-terminally blocked. It was thus proteolytically digested and four of the resulting peptides were sequenced comprising 47 amino acids. The sequences of these fragments were similar to the sequences reported for the small component of different two-component flavin monooxygenases. Furthermore, the N-terminus of the oxygenase component showed high sequence similarity to the second, usually large subunit of these enzymes and to two single-component flavin monooxygenases. Thus, the enzyme from Rhodococcus sp. designated as pyrrole-2-carboxylate monooxygenase belongs to the recently discovered new class of two-component flavin aromatic monooxygenases. Some of the basic properties of both components were determined and their interaction during catalysis was investigated.

Amino Acid Sequence↗
PubMed1997

Molecular basis of plant-specific acid activation of K+ uptake channels.

During stomatal opening potassium uptake into guard cells and K+ channel activation is tightly coupled to proton extrusion. The pH sensor of the K+ uptake channel in these motor cells has, however, not yet been identified. Electrophysiological investigations on the voltage-gated, inward rectifying K+ channel in guard cell protoplasts from Solanum tuberosum (KST1), and the kst1 gene product expressed in Xenopus oocytes revealed that pH dependence is an intrinsic property of the channel protein. Whereas extracellular acidification resulted in a shift of the voltage-dependence toward less negative voltages, the single-channel conductance was pH-insensitive. Mutational analysis allowed us to relate this acid activation to both extracellular histidines in KST1. One histidine is located within the linker between the transmembrane helices S3 and S4 (H160), and the other within the putative pore-forming region P between S5 and S6 (H271). When both histidines were substituted by alanines the double mutant completely lost its pH sensitivity. Among the single mutants, replacement of the pore histidine, which is highly conserved in plant K+ channels, increased or even inverted the pH sensitivity of KST1. From our molecular and biophysical analyses we conclude that both extracellular sites are part of the pH sensor in plant K+ uptake channels.

Asparagine↗
PubMed1997

Flow-cytometric screening for the modulation of receptor-mediated endocytosis in human dendritic cells: implications for the development of an in vitro technique for predictive testing of contact sensitizers.

The aim of this study was to explore the usefulness of human blood dendritic cells (DC) in the development of an in vitro model for predictive testing of contact sensitizers. A method was established to monitor the influence of chemicals on the intracellular targeting of antibody-crosslinked MHC class II molecules after their uptake by human DC. Using a three-colour flow-cytometric technique, freshly prepared DC were distinguished from other MHC class II-bearing cell types such as B-cells and monocytes in unseparated mononuclear cell suspensions of healthy volunteers. The assay is based on the pH-sensitivity of internalized fluorescein-coupled MHC class II specific antibodies. Quenching of fluorescence intensity due to internalization into acidic intracellular compartments was observed with untreated DC whereas internalization into less acidic structures following stimulation with strong contact sensitizers ensured that the fluorescence intensity was conserved. The usefulness of this approach for predictive testing of the preservatives MI/MCI, imidazolidinyl urea, methyl-4-hydroxy-benzoate and 2-phenoxyethanol in comparison to the strong allergen DNFB and the irritants sodium lauryl sulphate and dithranol was explored. Whereas low concentrations of MI/MCI resembled the strong allergen DNFB, high concentrations of imidazolidinyl urea were required for a moderate response. Methyl-4-hydroxy-benzoate and 2-phenoxyethanol as well as the irritants SLS and dithranol failed to induce a significant effect in this assay. The non-responsiveness to the latter compounds reflected their minor or absent capacity to induce contact hypersensitivity in humans, whereas DNFB, MI/MCI and imidazolidinyl urea are well established contact sensitizers. These data suggest that the capacity of a chemical to modulate endocytotic mechanisms in dendritic cells in vitro seems to reflect the probability of that substance acting as a hapten in vivo.

Antibodies, Monoclonal↗
PubMed1997

A phase-I clinical study of autologous tumor cells plus interleukin-2-gene-transfected allogeneic fibroblasts as a vaccine in patients with cancer.

Tumor cells transfected to express immunostimulatory cytokines, or admixed with similarly modified bystander cells, are able to induce immune responses against unmodified tumor cells in animal models. For treatment of human patients, a vaccine composed of autologous tumor cells and IL-2-secreting allogeneic fibroblasts was developed. Autologous tumor cells were isolated from biopsy specimens. A clone (KMST 6.14) of an immortalized human fibroblast line that stably secreted 5290 IU IL-2 per 10(6) cells and per 24 hr was obtained by cationic lipofection with an expression construct for human IL-2 and Neo(r). Fifteen patients with refractory malignant tumors received 3-4 injections of irradiated KMST6.14 and autologous tumor cells in a phase-I clinical trial. Increasing transient inflammatory responses without systemic toxicity developed at vaccination sites and after injections with irradiated tumor cells only (p < 0.05). These sites contained a dense infiltrate of CD3+ T cells with numbers of CD4+ helper cells exceeding those of CD8+ cytotoxic T cells (CTL). CD8+ T-cell lines isolated from vaccination sites of 2 malignant melanoma patients but not of renal-cell carcinoma patients exhibited a dominant lytic activity against autologous tumor cells in vitro. CD8+ T-cell clones established from the vaccination site of 1 of 2 renal-cell carcinoma patients preferentially lysed autologous and partially matched allogeneic renal-cell carcinoma cells. In conclusion, a vaccine composed of IL-2 gene-transfected allogeneic fibroblasts and autologous tumor cells is able to enhance specific anti-tumor T-cell responses in vivo without major side-effects. Malignant melanoma and renal-cell carcinoma appear to be promising entities for testing of similar approaches in future therapeutic trials.

Adult↗
PubMed1997

Thyroid autonomy with color-coded image-directed Doppler sonography: internal hypervascularization for the recognition of autonomous adenomas.

In a prospective study, we assessed the possibility of recognizing autonomous adenomas of the thyroid with color-coded image-directed Doppler sonography using internal hypervascularization in thyroid nodules for identification. Fifty-three patients with thyroid nodules underwent additional CCDS examination and nuclear scintigraphy (reference). Of 29 patients having autonomous adenomas, 28 patients presented internal hypervascularization in their nodules resulting in a sensitivity of 96% and a specificity was 75%. Interestingly CCDS detected six adenomas in patients showing normal laboratory data (bTSH, TT3, FT4). CCDS could be used to exclude focal adenomas with a negative predictive value of 94%. The positive predictive value for adenoma was 82%.

Adenoma↗
PubMed1997

Induction of tumor-specific cytotoxic T lymphocytes by immunization with autologous tumor cells and interleukin-2 gene transfected fibroblasts.

In a phase I trial designed to study a vaccine composed of autologous tumor cells and interleukin-2 gene transfected fibroblasts we analyzed lymphocytes infiltrating the vaccination site (VIL) in two melanoma patients. Functional studies demonstrated that numbers of MHC class I restricted cytotoxic T cells directed against the autologous tumor had increased at the immunization site in both cases. Analysis of the variability of T cell receptors (TCR) in the VIL of one patient revealed that the cytotoxic T lymphocytes consisted of a predominant population of TCRBV21S3+ T cells. Enrichment of this subpopulation to more than 99% by specific anti-TCRBV21S3 monoclonal antibody linked immunomagnetic beads and sequencing of the TCR-beta chain disclosed exactly the same V-D-J junctional sequence in all eight TCRBV21 transcripts from these VIL. The identical sequence was also detected in all eight TCRBV21 transcripts from the patient's tumor-infiltrating lymphocytes, indicating that the same CTL clone had infiltrated the tumor, circulated in the peripheral blood, and was amplified at the vaccination site. The TCRBV21S3+ T cells were also found to display an MHC class I restricted cytotoxic activity specifically directed against the autologous tumor cells. At the beginning of treatment these cells were undetectable at the vaccination site and delayed-type hypersensitivity testing was negative, contrasting with the positive results after therapy. Thus it is likely that vaccination with autologous tumor cells plus interleukin-2 gene transfected allogeneic fibroblasts had induced not only local accumulation but also an increase in the frequency of circulating tumor specific CTL.

Amino Acid Sequence↗
PubMed1997

Contact hypersensitivity to disodium hexachloroplatinate in mice.

Complex platinum (Pt) compounds are known as occupational respiratory sensitizers whereas their role in skin exposure is unclear. In this study, both skin irritation and induction of contact hypersensitivity by halide Pt salts were characterized in mice. Repeated application of Na2[PtCl6] (5% in acetone) to both ears of naive BALB/c mice induced activation of the draining auricular lymph nodes. Flow cytometric analysis revealed a striking increase in the number of lymph node cells expressing proliferating cell nuclear antigen. In separate experiments, Na2[PtCl6] or acetone were applied only to the right ear of mice on 4-8 consecutive days and the animals were challenged on the left ear 6 days later. Ear thickness was determined before and 0.5, 24, 48, and 72 h after challenge with 0.5 or 2% Na2[PtCl6] or acetone. Maximal swelling of the left ear was recorded at 48 h in Pt-sensitized mice challenged with 2% Na2[PtCl6]. Furthermore, the concentration of Na2[PtCl6] required for sensitization caused an irritant reaction as demonstrated by significant swelling of the right ear. These data support the concept that both irritant and allergic contact dermatitis to halide Pt salts may occur in humans. Concerning skin exposure to halide Pt salts, Pt-induced irritant reactions resulting from an intrinsic adjuvant's activity of the compound could be a prerequisite for sensitization.

Animals↗
PubMed1997

Mild head injury in children and adolescents: a review of studies (1970-1995).

In this article, the authors provide a comprehensive review of the research of mild head injury in children and adolescents from 1970 to 1995. Because of marked variability in methodologies across studies, a preliminary box-score tally was computed, without regard to studies' scientific or methodological merit. These results revealed 13 adverse, 18 null, and 9 indeterminate findings related to neuropsychological, academic, or psychosocial outcome. When studies were classified based on methodological merit, the stronger studies were generally associated with null outcomes across domains. However, a few of the less stronger neuropsychological studies (5 of 40) reported subthreshold and transitory alterations during the early postinjury period. At the present time, cautious acceptance of the null hypothesis is recommended until more definitive studies are conducted that address the problems raised in this review.

Achievement↗
PubMed1997

Antisense targeting of basic fibroblast growth factor and fibroblast growth factor receptor-1 in human melanomas blocks intratumoral angiogenesis and tumor growth.

Unlike normal melanocytes, primary and metastatic human melanomas express high levels of basic fibroblast growth factor (bFGF) and fibroblast growth factor receptor-1 (FGFR-1) messenger RNA, and expression of these genes is essential in sustaining the proliferation of malignant melanomas in vitro. To determine whether bFGF and FGFR-1 are also required for tumor formation in these cells, liposome-mediated gene transfer was used to deliver episomal vectors containing antisense-oriented bFGF or FGFR-1 cDNAs into human melanomas, grown as subcutaneous tumors in nude mice. The growth of tumors injected with these constructs was completely arrested or the tumors regressed as a result of blocked intratumoral angiogenesis and subsequent necrosis. Thus, inhibition of bFGF/FGFR-1-mediated signaling may open a new avenue for the treatment of advanced-stage melanomas.

Animals↗
PubMed1997

TGF-beta inhibits growth and induces apoptosis in leukemic B cell precursors.

The uncontrolled proliferation of malignant lymphoblasts is the pathobiological hallmark in B cell precursor-ALL (BCP-ALL). Identification of inhibitory growth factors is of great importance for the understanding of growth control of leukemic B cell precursors and the development of novel therapeutic approaches in BCP-ALL. The aim of our study was the analysis of the effect of TGF-beta on cell survival and apoptosis of B cell precursors (BCP) from patients with acute lymphoblastic leukemia in vitro. Experiments were performed in a coculture system with cloned murine fibroblasts, which efficiently block spontaneous ex vivo apoptosis of BCP and thus allows the assessment of cytokine-induced growth inhibition. TGF-beta significantly reduced cell viability of highly purified, FACS isolated CD10+/CD19+ leukemic BCP by a mean of 53% (P = 0.0001). The loss of cell viability was accompanied by a significant increase of apoptosis with a mean of 70% (P = 0.0028). The TGF-beta effect was blocked specifically by a monoclonal anti-TGF-beta antibody. Induction of apoptotic cell death by TGF-beta was not accompanied by reduction of bcl-2 protein expression. TGF-beta transcription was not detected in the leukemic pre-B cell line BLIN-1, but in the murine fibroblasts. The growth inhibitory effect of TGF-beta was not restricted to leukemic BCP. The cytokine also increased apoptosis of normal, highly purified BCP by a mean of 58%. The data identify TGF-beta as a potent growth inhibitory cytokine for leukemic BCP.

Animals↗