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M Burger

Publications and source records attributed to M Burger.

At least 37 records · Page 2Linked to original sources
PubMed2000

Autocrine growth effect of IL-8 and GROalpha on a human pancreatic cancer cell line, Capan-1.

A human pancreatic cancer cell line, Capan-1, secretes the chemokines interleukin-8 (IL-8) and growth-related oncogene alpha (GROalpha). Capan-1 cells also express the chemokine receptor 2 (CXCR2), which is a Gialpha-protein coupled receptor. Growth of Capan-1 cells was inhibited when anti-IL-8 or anti-GROalpha monoclonal antibody was added into the culture medium. Pertussis toxin, which blocks Gialpha also demonstrated a growth-inhibitory effect on Capan-1 cells. These results indicated that IL-8 and GROalpha act on Capan-1 cells as growth factors in an autocrine manner through CXCR2.

Antibodies, Monoclonal↗
PubMed1999

Chronic lymphocytic leukemia B cells express functional CXCR4 chemokine receptors that mediate spontaneous migration beneath bone marrow stromal cells.

Chemokines play a central role for lymphocyte trafficking and homing. The mechanisms that direct the tissue localization of B cells from patients with chronic lymphocytic leukemia (B-CLL) are unknown. We found that CLL B cells express functional CXCR4 receptors for the chemokine stromal cell-derived factor-1 (SDF-1), as demonstrated by receptor endocytosis, calcium mobilization, and actin polymerization assays. Moreover, CLL B cells displayed chemotaxis to this chemokine that could be inhibited by monoclonal antibodies (MoAbs) against CXCR4, pertussis toxin, or Wortmannin, a phosphatidylinositol 3-kinase inhibitor. That this chemotaxis may be involved in the homing of CLL cells is argued by studies in which CLL B cells were cocultured with a murine marrow stromal cell line that secretes SDF-1. Within 2 hours, CLL B cells spontaneously migrated beneath such stromal cells in vitro (pseudoemperipolesis). This migration could be inhibited by pretreatment of CLL B cells with anti-CXCR4 MoAbs, SDF-1alpha, or pertussis-toxin. Furthermore, we noted strong downmodulation of CXCR4 on CLL B cells that migrated into the stromal cell layer. These findings demonstrate that the chemokine receptor CXCR4 on CLL B cells plays a critical role for heterotypic adherence to marrow stromal cells and provide a new mechanism to account for the marrow infiltration by neoplastic B cells.

Cell Movement↗
PubMed1999

Point mutation causing constitutive signaling of CXCR2 leads to transforming activity similar to Kaposi's sarcoma herpesvirus-G protein-coupled receptor.

The chemokine receptor CXCR2 is the closest homologue to Kaposi's sarcoma herpesvirus-G protein-coupled receptor (KSHV-GPCR), which is known to be constitutively activated and able to cause oncogenic transformation. Among G protein-coupled receptors, a DRY sequence in the second intracellular loop is highly conserved. However, the KSHV-GPCR shows a VRY sequence instead. In this study, we exchanged Asp138 of the DRY sequence in the CXCR2 with a Val (D138V), the corresponding amino acid in KSHV-GPCR, or with a Gln (D138Q), and investigated the functional consequences of these mutations. In focus formation and soft agar growth assays in NIH 3T3 cells, the D138V mutant exhibited transforming potential similar to the KSHV-GPCR. Surprisingly, the CXCR2 wild type itself showed transforming activity, although not as potently, due to continuous autocrine stimulation, whereas the D138Q mutant formed no foci. In agreement with these results were high levels of inositol phosphate accumulation in the D138V mutant and the KSHV-GPCR, indicating constitutive activity. These data emphasize the importance of the DRY sequence for G protein-coupled signaling of the CXCR2. Either constitutive activation or persistent autocrine stimulation of the CXCR2 causes transformation similar to KSHV-GPCR-transfected cells, probably activating the same signal transduction cascade that can abrogate normal growth control mechanisms.

3T3 Cells↗
PubMed1999

In vitro differentiation and characterization of human peritoneal macrophages from CAPD-peritonitis patients.

Studies on human macrophages are restricted due to difficulties in isolating significant numbers of human macrophages. High numbers of monocytes/macrophages can be obtained from peritonitis effluents of patients treated with peritoneal dialysis. To determine whether these cells might be useful for functional studies, we characterized peritoneal macrophages (PM) immediately after isolation from the dialysate effluents and their subsequent differentiation. During a 10 days culture period they differentiated morphologically and phenotypically (FACS-analysis) from monocyte-like cells to macrophages. Reflecting the intraperitoneal inflammation we found protein- and mRNA-synthesis of IL-8 and monocyte-chemoattractant-protein-1 (MCP-1) to be upregulated in PM after isolation from the effluents. In contrast, TNF-alpha was downregulated and could not be stimulated by LPS and/or IFN-gamma, reflecting the phenomenon of desensitization. After 10 days in culture, cytokine production normalized to a constitutive level and the TNF-alpha responsiveness to LPS was restored. These data suggest the recovery of PM from the inflammatory prestimulation. Therefore PM harvested from peritoneal dialysis effluents might provide a useful tool for further studies on the role of human macrophages in inflammation.

Cell Differentiation↗
PubMed1999

Development and clinical evaluation of a highly sensitive PCR-reverse hybridization line probe assay for detection and identification of anogenital human papillomavirus.

Human papillomavirus (HPV) can be detected by amplification of viral DNA. A novel PCR primer set generating a short PCR fragment (SPF PCR) was used for amplification of a fragment of only 65 bp from the L1 region and permitted ultrasensitive detection of a broad spectrum of HPV genotypes. The intra- and intertypic sequence variations of the 22-bp interprimer region of this amplimer were studied. Among 238 HPV sequences from GenBank and clinical specimens, HPV genotypes were correctly identified based on the 22-bp sequence in 232 cases (97.2%). Genotype-specific probes for HPV genotypes 6, 11, 16, 18, 31, 33 to 35, 39, 40, 42 to 45, 51 to 54, 56, 58, 59, 66, 68, 70, and 74 were selected, and a reverse hybridization line probe assay (LiPA) (the INNO-LiPA HPV prototype research assay) was developed. This LiPA permits the use of amplimers generated by the SPF as well as the MY 09/11 primers. The assay was evaluated with a total of 1, 354 clinical specimens, comprising cervical scrapes (classifications ranging from normal cytology to severe dyskaryosis) and formalin-fixed, paraffin-embedded cervical carcinoma samples. LiPA results were highly concordant with sequence analysis of the SPF amplimer, genotype-specific PCR, and sequence analysis of amplimers generated by MY 09/11 primers. The sensitivity of the SPF primers was higher than that of the GP5(+)/6(+) primers over a broad range of HPV types, especially when multiple HPV genotypes were present. In conclusion, the SPF LiPA method allows extremely sensitive detection of HPV DNA as well as reliable identification of HPV genotypes in both cervical smears and paraffin-embedded materials.

Base Sequence↗
PubMed1998

Importance of the carboxy-terminus of the CXCR2 for signal transduction.

The CXCR2 is phosphorylated at the C-terminal intracytoplasmic portion within 15 sec following the addition of IL-8 or MGSA. Cells transfected with a truncated form of the receptor missing the last 12 amino acids (T3) showed normal binding affinity, but were no longer phosphorylated; individual alanine replacement indicated that Ser346 and 348 were the primary sites of phosphorylation. In studies of the importance of phosphorylation in CXCR2 desensitization, cells expressing wild type CXCR2 lost GTP gamma S binding above basal rate after the first exposure to IL-8, while cells with the T3 mutant retained 60% of their capacity to induce GTP gamma S exchange upon a second exposure to IL-8. In contrast, receptor internalization was not affected by the loss of phosphorylation of the T3 mutant. Further receptor truncation led to decreasing binding affinities for IL-8 and MGSA and a decreased rate of GTP gamma S exchange following addition of excess ligand which suggests involvement of this region in G-protein coupling.

Amino Acid Sequence↗
PubMed1998

Novel short-fragment PCR assay for highly sensitive broad-spectrum detection of anogenital human papillomaviruses.

A novel set of polymerase chain reaction (PCR) primers, designated SPF1 and SPF2 and located in the L1 region, was developed for universal detection of human papillomavirus (HPV). A short PCR fragment (SPF) of only 65 pb was synthesized. SPF amplimers were detected in a microtiter-based hybridization system, using a mixture of oligonucleotide probes. The SPF system allowed detection of at least 43 different HPV genotypes. The clinical performance of the novel SPF system was assessed in three different patient groups. 1) Analysis of 534 cervical scrapes, obtained from treated patients, showed that the detection rate in 447 (83.7%) scrapes with normal cytology was significantly higher using the SPF system as compared with the universal primer set GP5+/6+ (P < 0.001). 2) The SPF assay detected HPV DNA in 299 (98.4%) of 304 scrapes with cytological dyskaryosis. 3) The SPF system detected HPV DNA in 100% of 184 formalin-fixed, paraffin-embedded cervical carcinoma specimens. In conclusion, the novel SPF system permitted universal and highly sensitive detection of HPV DNA in diverse clinical materials and may improve the molecular diagnosis and epidemiology of this important virus.

Blotting, Southern↗
PubMed1998

Distinct regulation of IL-8 and MCP-1 by LPS and interferon-gamma-treated human peritoneal macrophages.

BACKGROUND: Interleukin-8 and monocyte chemotactic protein-1 (MCP-1) are major leukocyte chemoattractants during bacterial peritonitis by recruiting neutrophils and monocytes/macrophages respectively. METHODS: Peritoneal macrophages (PM) from 12 different CAPD patients with peritonitis were stimulated with either 10 ng/ml LPS, 10 ng/ml IFN-gamma or LPS+IFN-gamma, and IL-8 and MCP-1 production was determined on protein and mRNA levels by using ELISA technique and Northern blot analysis. To obtain information from two different stages of activation, experiments were done with highly activated PM directly after isolation and with cells after 10 days in culture, each group being stimulated for 4 h. Unstimulated cells served as control. RESULTS: Immediately after isolation IL-8 mRNA-expression and synthesis was high and could be further increased by LPS stimulation, whereas IFN-gamma treatment showed no significant influence. The levels of MCP-1 were also initially high but could not be further stimulated by LPS, whereas addition of IFN-gamma resulted in a significant rise in MCP-1 synthesis. After 10 days in culture LPS-stimulation of cells again revealed a significant increase in IL 8 protein synthesis, whereas IFN-gamma showed no effect. LPS anergy for MCP-1 was still seen in PM after 10 days in culture, and IFN-gamma treatment again induced a significant rise in MCP-1 synthesis. The overall production of both chemokines was far higher on day 1 compared to day 10. CONCLUSION: Our data show differences in LPS/IFN-gamma regulation for IL-8 and MCP-1 in both highly activated and in resting, mature peritoneal macrophages, suggesting distinct pathways for these chemokines that may offer a means of control for the specific recruitment of neutrophils and monocytes/macrophages in bacterial peritonitis.

Chemokine CCL2↗
PubMed1998

DNA fingerprinting of Mycobacterium tuberculosis complex culture isolates collected in Brazil and spotted onto filter paper.

The usefulness of filter paper for preservation of bacterial cells was shown by mixed-linker DNA fingerprint analysis of Mycobacterium tuberculosis isolates from 77 Brazilian patients. DNA fingerprints of samples spotted onto filter paper and conventional culture material were identical. Thus, filter paper specimens analyzed by an amplification-based typing method provide a new resource for epidemiological studies of infectious diseases.

Brazil↗
PubMed1998

The Ross procedure: Is it the ideal operation for the young with aortic valve disease?

BACKGROUND: Aortic valve prosthesis with adequate hemodynamic performance should allow more complete left ventricular mass regression and normalize left ventricular function. This possibly affects long-term prognosis after aortic valve replacement. OBJECTIVE: Assessment of hemodynamic performance of pulmonary autograft in the aortic position and the regression of left ventricular mass after the Ross procedure. METHODS: Between May 1995 and March 1996, 45 patients with mean age of 27.1 years underwent a Ross procedure. Doppler echocardiography and cardiac catheterization were performed on all patients before hospital discharge to evaluate the hemodynamic performance of auto- and homografts, as well as to evaluate left ventricular mass and function. Fourteen patients with follow-up longer than six months were submitted to dobutamine stress echocardiography to study the hemodynamic performance of auto- and homografts during exercise. RESULTS: Hospital mortality was 6%. After a mean follow-up of 12.8 months (1-23 months) there was one late sudden death. No valve-related event was observed during this period. Immediate and late hemodynamic performance of the pulmonary autografts were normal with an average mean gradient of 1.8 +/- 0.6 mmHg and an average maximum instantaneous gradient of 2.9 +/- 0.9 mmHg. Valvular insufficiency was insignificant. Even during exercise, gradients did not increase significantly with an average mean gradient of 4.3 +/- 2.5 mmHg and an average maximum gradient of 10.4 +/- 6.1 mmHg. Homografts used for right ventricular reconstruction showed excellent immediate hemodynamic performance. However, at late follow-up an increase in flow speed was observed with an average to mean gradient of 10 +/- 7.1 mmHg at rest and 26 +/- 13.2 mmHg during exercise. Left ventricular mass index was normal at rest and during exercise in the majority of patients. CONCLUSION: Given the normal hemodynamic function of pulmonary autografts, the reduction of ventricular mass and normalization of left ventricular function, in addition to the excellent late follow-up of the patients, the Ross procedure is considered the operation of choice for young patients requiring aortic valve replacement.

Adolescent↗
PubMed1997

[Bilateral renal artery stenosis diagnosed during pregnancy].

Bilateral renal artery stenosis was diagnosed noninvasively in the 17th gestational week, in a chronically hypertensive pregnant woman, by renal artery duplex ultrasound examination, MRI and MR angiography. Continuous monitoring of the mother and the fetus was performed. Blood pressure was stabilized by complex antihypertensive therapy, but from the beginning of the third trimester superimposed preeclampsia developed gradually. In the 34th gestational week a 1600-g newborn was delivered by elective cesarean section. The case report draws attention to the significance of the thorough examination of hypertensive women before pregnancy.

Adult↗
PubMed1997

Measurement of the pregnant cervix by transvaginal sonography: an interobserver study and new standards to improve the interobserver variability.

Transvaginal sonography has become an important tool for assessing the gravid cervix uteri, especially in patients at risk for cervical incompetence and preterm delivery. The purpose of our prospective study was to evaluate interobserver variability in measurements of the cervical length and, as a second step, improve the reproducibility and interobserver discrepancy by the introduction of quality control standards when producing and measuring the image of the cervix. Before the introduction of these standards we obtained 46 measurements and observed a mean cervical length (internal to external os) of 33.7 mm (range 26-52 mm) and an interobserver average discrepancy of 3.04 mm (range 0-6 mm). Later, measurements were obtained only when the following conditions were assured and visualized on the screen: (1) the internal os is either flat or is an isosceles triangle; (2) the whole length of the cervical canal can be observed; (3) a symmetric image of the external os can be obtained; and (4) the distance from the surface of the posterior lip to the cervical canal is equal to the distance from the anterior lip to the cervical canal. After the implementation of these quality control standards, 70 measurements were performed obtaining a mean length of 35.3 mm (range 27-51) and an average interobserver discrepancy of 1.24 mm (range 0-4). Thus the measurement error was significantly lower following introduction of quality control standards. Furthermore, the coefficient of variation dropped from 7.1% to 3.3% after the introduction of the guidelines. We believe that these guidelines could be helpful by making the measurements of the cervical length more accurate, reducing the interobserver variability, improving the reproducibility and promoting the role of transvaginal sonography in monitoring the incompetent cervix.

Cervix Uteri↗
PubMed1997

Improved cytosolic free calcium mobilization and superoxide production in bicarbonate-based peritoneal dialysis solution.

BACKGROUND: Intraperitoneal phagocytes play an important role in local host defence to prevent CAPD peritonitis. The intracellular calcium [Ca2+]i is thought to be involved in the regulation of various cell functions. This study therefore investigates the effect of lactate-based dialysis solution (LBDS) and bicarbonate-based dialysis solution (BBDS) on cytosolic free calcium mobilization and superoxide production (SP) as important steps in signal transduction and bacterial killing. METHODS: We studied changes in [Ca2+]i and SP following stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP) in polymorphonuclear neutrophils (PMNs) incubated in either LBDS-pH 5.2, LBDS adjusted to pH 7.4, 1:10 diluted spent and fresh LBDS or BBDS-pH 7.4 with different glucose concentrations, comparing the data with cells treated with Hanks buffer (HBSS) pH 7.4 as control. To elucidate the effect of glucose and lactate PMNs were additionally incubated in HBSS-pH 7.4, containing glucose (HBSS-Glu-pH 7.4) or lactate (HBSS-Lact-pH 7.4) in the same concentrations as contained in CAPD solutions and tested as above. PMNs were isolated from healthy blood donors and incubated with dialysis solution 10 min prior to stimulation with fMLP. RESULTS: [Ca2+]i mobilization and SP were completely inhibited in PMNs incubated in LBDS pH 5.2. pH adjustment of LBDS to 7.4 and 1:10 dilution of spent and fresh LBDS corrected some of the suppression of the calcium influx and superoxide production. BBDS pH 7.4, however, preserved physiological cell function significantly better at low (1.5 and 2.3%) glucose concentrations. CONCLUSION: In comparison to conventional lactate-based dialysis solution, pH adjusted and 1:10 diluted LBDS, bicarbonate-based dialysis solution is more biocompatible since it preserves significantly better neutrophil cell functions.

Bicarbonates↗
PubMed1997

Pyrimethamine-resistant Plasmodium falciparum parasites among Tanzanian children: a facility-based study using the polymerase chain reaction.

A mutation-specific polymerase chain reaction method was used to estimate the proportion of pyrimethamine-resistant parasites in 101 children reporting with malaria at the hospital in Ifakara, a town in southern Tanzania. The method is based on the observation that a point mutation (Asn-108) in the dihydroifolate reductase gene confers resistance to pyrimethamine. Twenty-eight percent of the examined 101 children had pyrimethamine-resistant parasites, 65% had pyrimethamine-sensitive parasites with the wild-type Ser-108 codon, and 9% had both alleles, suggesting a mixed infection. None of the 21 children with clinical malaria had pyrimethamine-resistant parasites. Currently, sulfadoxine-pyrimethamine is considered a potential first-line drug for malaria treatment in most African countries. We suggest that although sulfadoxine-pyrimethamine could still be effective against chloroquine-resistant malaria in this area, its judicious use is important so as to minimize the spread of resistance.

Animals↗
PubMed1996

Restructuring the clinical nurse specialist position to a unit-based role.

Role restructuring can be the key to maximizing efficiency, productivity, and operational effectiveness. The clinical nurse specialist role was restructured from a divisional project focus to a unit-based design to enhance the care of specific patient populations. The authors describe the process used to make this change, the outcomes achieved, and the lessons learned.

Efficiency, Organizational↗
PubMed1996

Effects of selective phosphodiesterase 3 inhibition in the perfused liver of the rat after endotoxin treatment.

1. This study was designed to investigate the role of rat phosphodiesterase 3 (RPDE3) in regulation of liver metabolism in sepsis. We studied the effects of the phosphodiesterase 3 inhibitor (PDI), enoximone, alone and in combination with regulating factors of hepatic carbohydrate metabolism and bile secretion in the perfused liver of rats treated 4 h earlier with endotoxin. In addition, cyclic AMP and cyclic GMP levels were determined in the effluate and bile by radio immunoassay methods. 2. After endotoxin treatment, infusion of enoximone at three concentrations (1 microM, 10 microM) resulted in an increased glucose output from -1.4 +/- 0.9 to 7.8 +/- 2.5 mumol l-1 20 min-1. Bile acid-independent bile flow increased also, in a dose-dependent manner. 3. In untreated livers, cyclic AMP release increased in the effluate from 1000 +/- 73 fmol g-1 min-1 to 1710 +/- 143 fmol g-1 min-1 when enoximone (10 microM) was administered. In bile from untreated livers, the level of cyclic AMP was also significantly increased by enoximone. After endotoxin treatment, the enoximone (10 microM) effect on cyclic AMP levels in effluate and bile was greatly reduced. Levels of cyclic GMP in the effluate and bile appeared unchanged in the presence of enoximone. 4. During co-infusion of glucagon (1 nM) and enoximone (10 microM), cyclic nucleotide levels in the effluate and bile of livers after endotoxin treatment were determined. In the effluate, cyclic AMP release increased from 827 +/- 144 fmol g-1 min-1 to 17802 +/- 2821 fmol g-1 min-1 when glucagon was administered. The presence of enoximone enhanced cyclic AMP further to 41696 +/- 920 fmol g-1 min-1. The same changes in cyclic AMP release were found in bile. Levels of cyclic GMP in the effluate and bile were not significantly affected by the administration of glucagon and the PDI. 5. Glucose release was determined during glucagon, sympathetic nerves stimulation and phenylephrine administration in the presence and absence of enoximone. The addition of enoximone to glucagon increased glucose release by 8.2 +/- 2.8 mumol g-1 20 min-1, without alteration of lactate balance. The PDI enhanced the glycogenolytic effects of nerve stimulation and of phenylephrine, accompanied by a reduction in lactate production. 6. Enoximone significantly enhanced the bile acid independent bile flow after glucagon, nerves stimulation and after administration of phenylephrine. Bile acid secretion was unaffected by the PDI. The vasoconstrictor effect of nerve stimulation was reduced by the PDI. 7. We conclude that endotoxin treatment reduces the ability of the PDI, enoximone, to increase cyclic AMP release in the perfused liver. The significant increase in cyclic AMP release after stimulation with glucagon and enoximone favours the view that RPDE3 is involved in the degradation of cyclic AMP in the liver after exposure to endotoxin. Additionally, the inhibition of the RPDE3 results in glucose release, vasodilatation and choleresis in endotoxin pretreated livers.

Animals↗