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Biomedical subjects

M Burger

Publications and source records attributed to M Burger.

At least 73 records · Page 4Linked to original sources
PubMed1989

Triple-phase bone image abnormalities in Lyme arthritis.

Arthritis is a frequent manifestation of Lyme disease. Limited triple-phase Tc-99m MDP bone imaging of the wrists and hands with delayed whole-body images was performed in a patient with Lyme arthritis. This demonstrated abnormal joint uptake in the wrists and hands in all three phases, with increased activity seen in other affected joints on delayed whole-body images. These findings are nonspecific and have been previously described in a variety of rheumatologic conditions, but not in Lyme disease. Lyme disease should be considered in the differential diagnosis of articular and periarticular bone scan abnormalities.

Bone and Bones↗
PubMed1989

Why I chose an HMO.

The advantages of family practice in an HMO are fixed hours, excellent call coverage, and immediate, steady outcome. Its disadvantages are less control over administrative decisions, less continuity of coverage than in solo practice, and great sensitivity to economic pressures. The author discusses how he came to his decision to practice family medicine in an HMO.

Career Choice↗
PubMed1987

Interplay between extracellular -SH groups and Ca2+ in their mitogenic action on murine lymphocytes: the role of SiO2.

Murine spleen lymphocytes, cultured under serum-free conditions and stimulated with concanavalin A (Con A), showed an increased demand for supplemental concentrations of Ca2+ when 2-mercaptoethanol (2-ME) or L-cysteine were also present in the culture medium. The requirement for additional Ca2+ ions was particularly evident at high cell concentrations. The addition of SiO2 (Aerosil 200), in concentrations depending on the original level of Ca2+ in the culture medium, could substitute for the increased demand on calcium ions. This dependency of SiO2 effects on calcium levels in the medium was also evident when supraoptimal, i.e. inhibitory concentrations of silica were tested. Results of experiments with 45Ca suggest that silica particles may act as intercellular carriers of calcium. In contrast to spleen lymphocytes, Con A-stimulated thymus cells exhibited neither a need for an increase in the concentration of Ca2+ nor a dependency on the presence of 2-ME in the medium.

Animals↗
PubMed1986

Stimulation of proliferation of murine lymphocytes by the calcium ionophore A 23187 in the absence of serum: the requirement for thiols.

The proliferation of mouse spleen cells and T-lymphocytes, initiated by the calcium ionophore A 23187 was studied by a serum-free culture technique. In contrast to Con A, A 23187 was capable of stimulating cells only if 2-mercaptoethanol, cysteine and glutathione (reduced form), respectively, were present in the culture medium. In the absence of one of these compounds a stimulating activity of A 23187 was observed only with high concentrations of cells (i.e., 10(7)/ml). With glutathione present, the cells could be stimulated only at concentrations of A 23187 which were found to be suboptimal in cultures with 2-mercaptoethanol. Human serum, fetal calf serum and bovine serum albumin shifted the active and optimally stimulating concentrations of A 23187 to higher values. A similar effect was observed with sera- and Con A-treated cells. The effect of sera and albumin was paralleled by a protecting effect of cells against high concentrations of A 23187.

Animals↗
PubMed1983

Enzymic properties of an N-acetylglucosaminide 3-alpha-L-fucosyltransferase of a wheat-germ agglutinin-resistant melanoma clone.

A fucosyltransferase was solubilized by extraction with Triton CF-54 from a wheat-germ agglutinin-resistant variant of mouse B16 melanoma. Through affinity chromatography on GDP hexanolamine--Sepharose a 44-fold enrichment of its specific activity was obtained. Analysis of its specificity indicated that the enzyme is an N-acetylglucosaminide 3-alpha-L-fucosyltransferase, which is able to transfer fucose to oligosaccharides containing Gal(beta 1-4)GlcNAc and Gal(beta 1-4)Glc structures. The enzyme is activated by divalent cations and has a maximum of activity at pH 5. It is unable to transfer fucose to sialylated glycoproteins, 6-alpha-sialyllactose or 3-alpha-sialyllactose. As suggested by its precipitation in the presence of antibodies raised in rabbit against a soluble human milk N-acetylglucosaminide 3-alpha-L-fucosyltransferase, these two enzymes seem to be structurally related.

Agglutination Tests↗
PubMed1983

The mechanism of SiO2 (Aerosil)-mediated enhancement of the proliferative response of mouse spleen lymphocytes to antigen and mitogens in a serum-free system.

SiO2 particles enhanced the in vitro proliferation of splenic B cells obtained from BALB/c mice immunized with sheep erythrocytes. T cells from immunized animals were capable of replacing SiO2 with regard to the enhancement of both in vitro proliferation and the primary immune response. In addition, the stimulating effect of IgG, phytohemagglutinin (PHA) and concanavalin A (Con A) on spleen lymphocytes was also augmented by SiO2. The enhancing effect of SiO2 was higher at suboptimal than at supraoptimal concentrations of Con A. SiO2 is capable of binding Con A. The SiO2-bound lectin retained its mitogenic effect on spleen cells and, under certain conditions, SiO2-bound Con A was considerably more active in this respect than the free substance.

Animals↗
PubMed1982

The role of 2-mercaptoethanol in the stimulation of spleen cell cultures: increased uptake of cystine into the TCA-soluble pool.

A sensitive system for the study of the mechanism of action 2-mercaptoethanol in stimulating of mouse spleen cell cultures is described. In this system the triggering of stimulation of cells by a mitogen or antigen was dependent on the presence of 2-mercaptoethanol (2-ME) in the medium. To obtain a similar stimulatory effect, 2-ME could be replaced by L-cystine or L-cysteine in the presence or absence of a mitogen. In the presence of a mitogen and below the saturation level, cystine was more effective than cysteine. By increasing in this system, the cystine concentration, to the double of that of the basal medium, a strong stimulation of cells was produced. Conversely, in the absence of mitogen, cysteine was significantly more effective than cystine. Addition of 2-ME led to an increased entry of [14C]L-cystine into the TCA-soluble pool of cells while the thiol had no influence on the uptake of a mixture of different amino acids. We conclude that in this system the role of 2-ME is to enable the utilization of otherwise ineffectively low concentrations of cystine by enhancing the entry of this amino acid into the amino acid pool of the cells.

Animals↗
PubMed1982

["Dry eye" and artificial tear solutions (author's transl)].

Seventeen patients in whom "dry eye" had been diagnosed each tried four coded commercial artificial tear solutions for one week, in random sequence. The correlation of the function tests (Schirmer test, break-up tie, goblet cell count in conjunctival biopsy) did not permit a grouping of the patients. A tendency to a correlation between break-up time and goblet cell count was noted. It was not possible to show a preference on the part of certain patients for particular products; thus, with the current function tests available, a precise therapeutic classification of "dry eye" patients does not seem possible.

Adult↗
PubMed1982

[Aniridia caused by contusion-related rupture of a bleb following Elliot's trepanation].

This case report deals with a 68-year-old man in whom a contusion resulted in a complete loss of the iris through an Elliot fistula. The abrupt increase in intraocular pressure caused the iris to be extruded through the fistula and the ruptured conjunctiva. A functional drainage bleb was reconstructed by pulling and suturing subconjunctival tissue underneath the ruptured conjunctiva.

Aged↗
PubMed1982

Immunization of mouse spleen cell cultures in the absence of serum and its proteins using SiO2 and 2-mercaptoethanol.

High recoveries of plaque-forming cells were obtained in a serum-free medium using 2-mercaptoethanol and SiO2. Under such conditions an increase in the number of plaque-forming cells occurred between the fourth and fifth day of incubation, as compared with cultures with foetal calf serum. The addition of glutathione to the medium had a stimulating effect, it was however not absolutely necessary for a positive response. The recovery of plaque-forming cells was strongly influenced by an interdependence of cell density and amount of SiO2 gel particles.

Animals↗
PubMed1982

Radioimmunoassay for vasoactive intestinal polypeptide (VIP) in plasma before and during endoscopic examinations.

A specific and sensitive radioimmunoassay of human vasoactive intestinal polypeptide using synthetic VIP as standard preparation and antiserum to synthetic VIP R 502 (Yanaihara et al. 15) is described. No crossreactions with a number of other gastrointestinal hormones such as glucagon, secretin, GIP, HPP or substance P was detected. Aprotinin (Trasylol, Bayer) or heparin had no influence on the antigen--antibody reaction. High concentrations of sodium or potassium chloride in plasma, or hyperlipoproteinemia, did not interfere with the antiserum in the described system. Basal plasma concentration of VIP in 18 females (means +/- sem = 24.05 +/- 1.79 VIP/l) and 20 males (means +/- sem = 24.11 +/- 1.91 pmol/l VIP) showed no sex specific variations. During gastroscopy plasma VIP levels were significantly higher than basal values, showing a peak secretion when the gastric antrum was inspected. During the entire colonoscopic examination, VIP levels were significantly higher than basal values. Endoscopic examination may possibly liberate VIP from the VIP containing cells which can be found throughout the gastrointestinal tract.

Adolescent↗
PubMed1980

The in vitro immune response in the absence of serum and its proteins: stimulating activity of zymosan.

In the absence of serum and its components, zymosan, together with 2-mercaptoethanol present in the medium, stimulated the in vitro primary immune response. Zymosan was effective at a concentration of as low as 2.5 microgram/ml. Removal of macrophages using iron powder resulted in higher recoveries of plaque-forming cells in the presence of zymosan but not of fetuin. Since insoluble zymosan may be easily removed from the culture, the test system described might be suitable for the identification of specific control factors secreted by cells during the in vitro immune response.

Animals↗
PubMed1980

Fibronectin in the developing sea urchin embryo.

The presence of fibronectin in developing sea urchin embryos was studied uing immunofluorescence staining. The fluorescence pattern indicates that fibronectin is found on the cell surfaces and between cells in the blastula and gastrula stages, indicating that it plays a role in cell adhesion. Its presence on invaginating cells also suggests its involvement in morphogenesis during early development.

Animals↗
PubMed1979

An absolute requirement for 2-mercaptoethanol in the in vitro primary immune response in the absence of serum.

Using a serum-free medium, high recoveries of plaque-forming cells (PFCs) were obtained up to 5 days of incubation in the in vitro primary immune response. Under these conditions, the presence in the medium of 2-mercaptoethanol was an absolute requirement. In order to obtain maximal recoveries of PFCs, the antigen and 2-mercaptoethanol had to be present from the start of the culture, while the addition of fetuin could be delayed for 24 h without any loss of PFCs. The 2-mercaptoethanol could be replaced by (dialysed) human serum.

Animals↗