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Biomedical subjects

R Christian

Publications and source records attributed to R Christian.

At least 19 recordsLinked to original sources
PubMed2001

Purification and structure elucidation of the N-acetylbacillosamine-containing polysaccharide from Bacillus licheniformis ATCC 9945.

The exopolysaccharide of Bacillus licheniformis ATCC 9945 (formerly B. subtilis ATCC 9945) contains among other glycoses 4-acetamido-2-amino-2,4,6-trideoxy-D-glucose, termed N-acetylbacillosamine (Bac2N4NAc). A similar diamino glycose, 2-acetamido-4-amino-2,4,6-trideoxy-D-glucose, was found in a surface layer (S-layer) glycoprotein preparation of Clostridium symbiosum HB25. Electron microscopic studies, however, showed that B. licheniformis ATCC 9945 is not covered with an S-layer lattice, indicating that the N-acetylbacillosamine present in that organism might be a constituent of a cell wall-associated polymer. For elucidation of the structure of the N-acetylbacillosamine-containing polysaccharide, it was purified from a trichloroacetic acid extract of B. licheniformis ATCC 9945 cells. Using different hydrolysis protocols and a hydrolysate of the S-layer glycoprotein preparation from C. symbiosum HB25 as reference, the purified polysaccharide was found to contain 2,4-diamino-2,4,6-trideoxy-glucose, 2-acetamido-2-deoxy-glucose, 2-acetamido-2-deoxy-galactose and galactose in a molar ratio of 1 : 1 : 1 : 2. One- and two-dimensional NMR spectroscopy, including 800 MHz proton magnetic resonance measurements, in combination with chemical modification and degradation experiments, revealed that the polysaccharide consists of identical pyruvylated pentasaccharide repeating units with the structure: [-->3)-[(S)Py-(3,4)-beta-D-Galp-(1-->6)]-alpha-D-GlcpNAc-(1-->3)-beta-D-Bacp2N4NAc-(1-->3)-[(S)Py-(3,4)-beta-D-Galp-(1-->6)]-beta-D-GalpNAc-(1-->](n)

Acetylation↗
PubMed2001

Exploring the value of shiatsu in palliative care day services.

This qualitative study sought to evaluate the effects of shiatsu therapy on clients attending hospice day services. Eleven clients with advanced progressive disease received five therapy sessions each at weekly intervals. Data about the effects was collected through five unstructured interviews with each client. Four of these were conducted before, during, and shortly after the therapy regime, and the fifth was undertaken four weeks after treatment ended. All the interviews were tape-recorded, transcribed and subject to content analysis. The results of the analysis revealed significant improvements in energy levels, relaxation, confidence, symptom control, clarity of thought and mobility. These benefits were of variable duration - in some instances lasting a few hours but in others extending beyond the 5-week treatment regime. Action to ensure research trustworthiness included keeping research journals to provide an audit trail, conducting member checks and using peer debriefing. The study involved three overlapping cohorts of participants in a data collection period that took approximately 6 months.

Acupressure↗
PubMed2000

A pyrophosphate bridge links the pyruvate-containing secondary cell wall polymer of Paenibacillus alvei CCM 2051 to muramic acid.

The peptidoglycan, the secondary cell wall polymer (SCWP), and the surface layer (S-layer) glycoprotein are the major glycosylated cell wall components of Paenibacillus alvei CCM 2051. In this report, the complete structure of the SCWP, its linkage to the peptidoglycan layer, and its physicochemical properties have been investigated. From the combined evidence of chemical and structural analyses together with one- and two-dimensional nuclear magnetic resonance spectroscopy, the following structure of the SCWP-peptidoglycan complex is proposed: [(Pyr4,6)-beta-D-ManpNAc-(1-->4)-beta-D-GlcpNAc-(1-->3)]n-11-(Pyr4,6)-beta-D-ManpNAc-(1-->4)-alpha-D-GlcpNAc-(1-->O)-PO2-O-PO2-(O-->6)-MurNAc- Each disaccharide unit is substituted by 4,6-linked pyruvic acid residues. Under mild acidic conditions, up to 50% of them are lost, leaving non-substituted ManNAc residues. The anionic glycan chains constituting the SCWP are randomly linked via pyrophosphate groups to C-6 of muramic acid residues of the peptidoglycan layer. 31P NMR reveals two signals that, as a consequence of micelle formation, experience different line broadening. Therefore, their integral ratio deviates significantly from 1:1. By treatment with ethylenediaminetetraacetic acid, sodium dodecyl sulfate, and sonication immediately prior to NMR measurement, this ratio approaches unity. The reversibility of this behavior corroborates the presence of a pyrophosphate linker in this SCWP-peptidoglycan complex. In addition to the determination of the structure and linkage of the SCWP, a possible scenario for its biological function is discussed.

Bacillus↗
PubMed1999

Complete glycan structure of the S-layer glycoprotein of Aneurinibacillus thermoaerophilus GS4-97.

Isolate GS4-97 was purified from an extraction juice sample of an Austrian beet sugar factory and affiliated to the newly described species Aneurinibacillus thermoaerophilus. It is closely related to the type strain of this species, A.thermoaerophilus L420-91(T), and possesses a square surface layer (S-layer) array composed of identical glycoprotein monomers as its outermost cell envelope component. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified S-layer showed an apparent molecular mass of approximately 109,000. After thorough proteolytic degradation of this material by pronase E and purification of the reaction mixture by gel permeation, chromatofocusing, and reversed-phase chromatography, a homogeneous glycopeptide fraction was obtained which was subjected to one- and two-dimensional nuclear magnetic resonance spectroscopy. The combined chemical and spectroscopic evidence, together with N-terminal sequencing, suggest the following structure of the O-glycosidically linked S-layer glycan chain of the glycopeptide: This is the first description of a beta-d-GalNAc-Thr linkage in glycoproteins.

Bacterial Proteins↗
PubMed1998

Self-expandable metal stents for malignant gastric outlet obstruction: a modified technique.

BACKGROUND AND STUDY AIMS: Endoscopic palliative treatment may be effective in the management of malignant gastric outlet obstruction. However, experience in this area is limited, and the techniques vary widely. In this retrospective study, a uniform technique using nearly identical self-expandable metal stents was employed to assess technical feasibility, safety, and outcome. PATIENTS AND METHODS: Eight patients presenting with clinical findings of gastric outlet obstruction confirmed by upper gastrointestinal radiography underwent endoscopic placement of expandable metal stents. All patients had primary or metastatic malignancy involving the pylorus or duodenum. Endoscopic and Gastrografin-enhanced upper gastrointestinal radiographic evaluations were carried out immediately after stent placement. Complications and clinical outcomes were assessed in each patient. RESULTS: Five patients had extrinsic compression of the descending duodenum due to pancreatic cancer, two had pyloric stenosis from metastatic cancer, and one patient had primary duodenal cancer. Stent placement was successful in all patients, and was followed by clinical improvement. There was one death within 30 days, related to pneumonia. CONCLUSION: Endoscopic self-expandable stent placement appears to be a reasonable therapeutic alternative in patients with malignant gastric outlet obstruction.

Aged↗
PubMed1997

Automated cardiac output measurement by spatiotemporal integration of color Doppler data. In vitro and clinical validation.

BACKGROUND: A new Doppler echocardiographic technique has been developed for automated cardiac output measurement (ACOM) that assumes neither a flat flow profile nor collinearity with the scan line, but clinical validation of this method is lacking. METHODS AND RESULTS: In 165 subjects (50 intensive care patients, 10 dobutamine echocardiography patients, and 105 normal volunteers; age, 49.4 +/- 19.3 years; 92 men), ACOM was performed in the left ventricular outflow tract (LVOT), with the color baseline shifted to avoid aliasing. ACOM was also tested in a pulsatile in vitro model. Stroke volume was calculated by double integration of Doppler signals in space (across the LVOT) and in time (through the systolic period), assuming hemiaxial symmetry: integral of integral of pi r v(r,t) dr dt, where v(r,t) is the velocity at a distance r from the center of the LVOT at time t during systole. Stroke volume from ACOM was compared with thermodilution (TD), aortic valve pulsed-wave Doppler (PWAO), and left ventricular echocardiographic (two-dimensional [2D]) methods. There was good correlation between ACOM and PWAO (r = .93). TD (r = .86), and 2D (r = .74), with close agreement seen. ACOM had higher correlation and agreement with TD than did either PWAO (P < .02) or 2D (P < .01). ACOM was also able to track accurately the changes in cardiac output with dobutamine infusion in comparison with PWAO (r = .94). In vitro assessment demonstrated excellent correlation (r = .98, y = 1.0x + 1.94) with little impact of pulse repetition frequency or misalignment up to 30 degrees. Gain dependency was noted but could be optimized by visual inspection of the color image. CONCLUSIONS: Automatic integration of numerical data within color Doppler flow fields is a feasible new method for quantifying flow. It is simpler and faster, requires fewer assumptions, and uses only one apical view. ACOM is a promising new approach to echocardiographic quantification that deserves further study and refinement.

Adolescent↗
PubMed1997

Large-core needle biopsy of nonpalpable breast cancers. The impact on subsequent surgical excisions.

OBJECTIVE: To compare the subsequent surgical therapy for women with nonpalpable breast cancers diagnosed by large-core needle biopsy (LCNB) vs those diagnosed by surgical excision after wire localization. DESIGN: Retrospective review of cases and results. SETTING: Secondary referred care. PATIENTS: A total of 677 women diagnosed as having breast cancer by LCNB (n = 67) or by surgical excision after wire localization (n = 610). RESULTS: Women in the LCNB group underwent an average of 1.25 surgical procedures and women whose breast cancers were diagnosed by surgical excision after preoperative wire localization underwent an average of 2.01 surgical procedures (P < .001). CONCLUSIONS: Large-core needle biopsy decreases the number of surgical procedures in women diagnosed as having nonpalpable breast cancers. Increased implementation of this technique will substantially decrease the costs of surgical therapy in these patients.

Biopsy, Needle↗
PubMed1996

Peristomal hidradenitis suppurativa.

Hidradenitis suppurativa is a chronic, suppurative, and cicatricial cutaneous disease with clinical manifestations including inflammatory lesions and nodules, abscesses, and sinus tracts. We describe an unusual case of peristomal lesions that may represent hidradenitis suppurativa. Peristomal hidradenitis suppurativa has not been previously reported. This unusual complication demonstrates the need for a thorough patient history to identify any systemic disease that may contribute to peristomal skin problems.

Crohn Disease↗
PubMed1995

Glycan structure of the S-layer glycoprotein of Bacillus sp. L420-91.

Preliminary taxonomic characterization of isolate L420-91 has revealed that this organism is closely related to the species Bacillus aneurinolyticus. The bacterium is covered by a squarely arranged crystalline surface layer composed of identical glycoprotein subunits with an apparent molecular mass in the range of 109 kDa. A total carbohydrate content of approximately 3.5% (wt/wt) was determined in the purified surface layer glycoprotein. Glycopeptides were obtained after exhaustive Pronase digestion and purification including gel filtration, ion exchange chromatography and HPLC. From the combined evidence of composition analysis. Smith degradation and nuclear magnetic resonance spectroscopy experiments we propose the following structure for the glycan chain of the surface layer glycoprotein: [formula: see text]

Acetamides↗
PubMed1995

The value of possessions in compulsive hoarding: patterns of use and attachment.

Hoarding behavior, patterns of use of possessions, and emotional attachment to possessions were examined among a sample of female undergraduates and a sample of community volunteers. Hoarding behavior was associated with a decreased frequency of use of possessions and excessive concern about maintaining control over possessions. Furthermore, high scores on the hoarding scale were associated with higher levels of perceived responsibility for: (1) being prepared; and (2) the well-being of the possession. Hoarding was also associated with greater emotional attachment to possessions and to the reliance on possessions for emotional comfort. The implications of these findings for the definition of hoarding are discussed.

Adult↗
PubMed1995

Glycan structure of a heptose-containing S-layer glycoprotein of Bacillus thermoaerophilus.

The characterization of the S-layer glycoprotein of Bacillus thermoaerophilus revealed unexpected novelties. The isolation and purification procedure had to be changed due to complete solubility in aqueous buffers of the constituting S-layer protomers. Upon degradation of the S-layer glycoprotein by pronase and purification of the products by gel filtration, ion-exchange chromatography, chromatofocusing and HPLC, one representative glycopeptide fraction was selected for further characterization. From the combined evidence of composition analysis, chemical degradation, NMR spectroscopy experiments and comparison with synthesized model substance, we propose the following repeating unit structure of the glycan chain: -->4)-alpha-L-Rhap-(1-->3)-beta-D-glycero-D-manno-Hepp-(1--> This is the first description of heptose residues occurring as a constituent of S-layer glycoproteins of gram-positive eubacteria.

Bacillus↗
PubMed1995

Similarity of "core" structures in two different glycans of tyrosine-linked eubacterial S-layer glycoproteins.

Previously, the repeating-unit structure of the S-layer glycoprotein from the eubacterium Bacillus alvei CCM 2051 has been determined to be [-->3)-beta-D-Galp-(1-->4)-[alpha-D-Glcp-(1-->6)-]-beta-D-ManpNAc- (1-->]n (E. Altman, J.-R. Brisson, P. Messner, and U. B. Sleytr, Biochem. Cell Biol. 69:72-78, 1991). Nuclear magnetic resonance spectroscopic reexamination of this glycan reveals that the O-antigen-like domain of the polysaccharide is [see text] connected with the S-layer polypeptide through the "core" structure -->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->3)-alpha-L-R hap-(1-->3)-beta-D-Galp-(1-->O)-Tyr. Except for the substitution in position 4 of the nonreducing rhamnose with the modified glyceric acid phosphate residue GroA-2-->OPO2-->4-beta-D-ManpNAc-(1-->, this core is identical to the core of the tyrosine-linked glycan from the S-layer glycoprotein of Thermoanaerobacter thermohydrosulfuricus L111-69 (K. Bock, J. Schuster-Kolbe, E. Altman, G. Allmaier, B. Stahl, R. Christian, U. B. Sleytr, and P. Messner, J. Biol. Chem. 269:7137-7144, 1994).

Bacillus↗
PubMed1994

Primary structure of the O-glycosidically linked glycan chain of the crystalline surface layer glycoprotein of Thermoanaerobacter thermohydrosulfuricus L111-69. Galactosyl tyrosine as a novel linkage unit.

The products of Pronase digestion of the crystalline surface layer (S-layer) glycoproteins of Thermoanaerobacter thermohydrosulfuricus strains L111-69 and L110-69 were isolated by gel permeation chromatography, cation exchange chromatography, chromatofocusing, and reversed phase high performance liquid chromatography. Four compounds were obtained which were analyzed by monosaccharide analysis, one- and two-dimensional 500 and 600 MHz 1H and 13C NMR spectroscopy, methylation analysis, gas-liquid chromatography/mass spectrometry, and matrix-assisted laser desorption ionization mass spectrometry. For all glycopeptides we propose the following glycan structure with galactose as the linkage sugar. [formula: see text] The isolated glycopeptides resulted from Pronase cleavage at the glycosylated tyrosine residues. Tyrosine was found as the linkage amino acid in all fractions but the remaining amino acid sequences varied, indicating the presence of different glycosylation sites in the intact S-layer glycoprotein.

Bacterial Proteins↗
PubMed1994

A new gene of bacteriophage P4 that controls DNA replication.

Bacteriophage P4 replication may result in either a lytic cycle or plasmid maintenance, depending on the presence or absence, respectively, of helper phase P2 genome. Bacteriophage P4 DNA replication depends on the product of gene alpha, which has origin recognition, primase, and helicase activities. An open reading frame with the coding capacity for a protein of 106 amino acids (orf106) is located upstream of the alpha gene. Genes orf106 and alpha are transcriptionally coregulated. Three amber mutations and an internal deletion (del51) were introduced into orf106. All of the amber mutations exhibited a polar effect on transcription of the downstream alpha gene. The P4 del51 mutant was slightly defective in lytic growth and could not be propagated in the plasmid state. In this latter condition, P4 DNA overreplication was observed. Overexpression of Orf106 severely inhibited P4 DNA replication, preventing P4 lytic growth and plasmid maintenance. The inhibitory effect of Orf106 on P4 replication was not observed when both orf106 and alpha were overexpressed. We suggest that orf106 is involved in P4 replication and that a balanced expression of orf106 relative to alpha may be necessary for proper P4 DNA replication. In particular, orf106 appears to be essential for the control of P4 genome replication in the plasmid state. We propose that orf106 be named cnr, for copy number regulation.

Amino Acid Sequence↗
PubMed1993

Chest wall recurrence of ductal carcinoma in situ of the breast after mastectomy.

BACKGROUND: Optimal management of ductal carcinoma in situ (DCIS) of the breast is a problem that is occurring with greater frequency, mostly because of the increasing use of mammographic screening. The traditional role of mastectomy for DCIS has been challenged by breast-conserving procedures. Regardless of the method of treatment used, local control with complete tumor eradication is the major goal in the management of DCIS. METHODS AND RESULTS: A patient is reported in whom DCIS recurred in residual breast tissue in the chest wall several years after mastectomy. CONCLUSIONS: Chest wall recurrence of DCIS within residual breast tissue probably is caused by failure of tumor excision, new primary tumor, or both. This observation underscores that (1) mastectomy may not result in complete removal of breast tissue, and (2) this residual breast tissue may be the substrate for "chest wall recurrences" in some patients with breast cancer.

Adult↗
PubMed1993

Synthesis and NMR spectroscopic investigation of oligosaccharides containing Kdo and L-glycero-D-manno-heptopyranosyl residues.

The disaccharides O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->8)-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (8), O-L-glycero-alpha-D-manno-heptopyranosyl-(1-->7)-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (12), and O-alpha-D-mannopyranosyl-(1-->7)-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (21) and the branched trisaccharides O-L-glycero-alpha-D-manno-heptopyranosyl-(1-->7)-[O-(sodium 3-deoxy-alpha- and -beta-D-manno-2-octulopyranosylonate)-(2-->8)]-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (15 and 16) and O-alpha-D-mannopyranosyl-(1-->7)-[O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->8)]-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (24) were prepared. Per-O-acetylated mannopyranosyl or Kdo bromide derivatives were employed for the glycosylation steps under Helferich conditions, whereas the imidate derivative 9 was used for the coupling of the L-glycero-D-manno-heptopyranosyl residues. The oligosaccharides were fully characterized by NMR spectroscopic data. Their structures correspond to an artificial linkage pattern providing a potential cross-reactive epitope for antibodies directed against the inner-core-region of enterobacterial as well as chlamydial lipopolysaccharides.

Carbohydrate Conformation↗
PubMed1993

Long-term insulin treatment of vascular smooth muscle cells from rat aorta attenuates the synergistic effect of insulin on angiotensin II- and epidermal growth factor-induced DNA synthesis.

1. In the present study the effects of acute and chronic insulin treatment on growth factor-induced cell growth were investigated in vascular smooth muscle cells. Cell growth was quantified by the incorporation of [3H]thymidine into cell DNA and by determination of total protein. 2. Insulin in a concentration range of 10(-9)-10(-6) mol/l had no effect on cell DNA synthesis. Insulin-like growth factor-1 in a concentration range of 10(-9)-10(-6) mol/l induced a concentration-dependent increase in total cell protein, whereas no changes in DNA synthesis were observed. 3. Acutely, insulin enhanced the mitogenic effect of epidermal growth factor and angiotensin II. Long-term treatment with 10 and 100 ng/ml insulin over 14 weeks was associated with a time-dependent reduction in this potentiating effect of insulin on growth factor-induced DNA synthesis. To evaluate the mechanism of this effect, receptor binding studies were performed with 125I-labelled insulin-like growth factor-1. No difference in the Kd value (2.1 nmol/l) for insulin-like growth factor-1 was found between untreated and chronically insulin-treated cells, whereas the maximal number of binding sites decreased from 5.9 x 10(4) (untreated cells) to 4.7 x 10(4) (10 ng/ml) and to 4.3 x 10(4) (100 ng/ml) binding sites/cell in chronically insulin-treated cells. 4. We conclude that insulin acutely enhances the mitogenic effect of various growth factors such as epidermal growth factor and angiotensin II on vascular smooth muscle cells. Long-term insulin treatment reduced the number of receptor binding sites for insulin-like growth factor-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗