Biomedical subjects
Publications and source records attributed to R W Carlson.
The incidence of coccidiodomycosis in the southwestern United States has sharply increased over the last decade as a result of environmental and demographic changes. It is important to review the epidemiology, diagnostic indicators, and therapeutic options for both immunocompetent and immunocompromised patients who have a particularly high risk of infection.
Reflectance spectra in the 1- to 2.5-micrometer wavelength region of the surface of Europa obtained by Galileo's Near Infrared Mapping Spectrometer exhibit distorted water absorption bands that indicate the presence of hydrated minerals. The laboratory spectra of hydrated salt minerals such as magnesium sulfates and sodium carbonates and mixtures of these minerals provide a close match to the Europa spectra. The distorted bands are only observed in the optically darker areas of Europa, including the lineaments, and may represent evaporite deposits formed by water, rich in dissolved salts, reaching the surface from a water-rich layer underlying an ice crust.
The structural arrangement of oligosaccharides comprising the core region of Rhizobium etli CE3 lipopolysaccharide (LPS) has been elucidated through the characterization of the LPSs from two R. etli mutants. One mutant, CE358, completely lacks the O-chain polysaccharide, while the second mutant, CE359, contains a truncated portion of this polysaccharide. This structural arrangement of the core oligosaccharides in these LPSs was determined using electrospray ionization mass spectrometry, tandem mass spectrometry, and methylation analysis. Mild acid hydrolysis of the CE359 LPS produces two major core oligosaccharides: a tetrasaccharide (1) with the structure alpha-D-Galp-(1-->6)-[alpha-D-GalpA-(1-->4)]-alpha-D-Manp-(1 -->5)-Kdo p (where Kdo represents 3-deoxy-D-manno-2-octulosonic acid) and a trisaccharide (2) having the structure alpha-D-GalpA-(1-->4)-[alpha-D-GalpA-(1-->5)]-Kdop. Structure 1 in CE358 LPS lacks the galacturonosyl residue. Glycosyl linkage and tandem mass spectrometry analyses show that the intact LPS core region consists of trisaccharide (2) attached to O-4 of the Kdo residue in tetrasaccharide 1, and that an additional Kdo residue is attached to O-6 of the galactosyl residue of 1. [structure: see text] The additional terminally linked Kdo residue is not in close proximity to the lipid A moiety, a unique location for a core Kdo residue. The mutant LPS preparations also contain minor LPS species, one of which lacks the Kdo linked to O-6 of the galactosyl residue, another that lacks the galacturonic acid attached to O-5 of Kdo, and a third that lacks two galacturonosyl residues and one Kdo residue. Thus, in addition to lacking both heptose and phosphate, the R. etli LPS core region differs substantially from the typical enterobacterial cores. The abundance of galacturonosyl residues in the R. etli core might serve as a suitable functional replacement for phosphate, such as would be predicted for Ca2+ binding.
The structure of the exopolysaccharide produced by Alteromonas macleodii subsp. fijiensis recovered from a deep-sea hydrothermal vent has been investigated. By means of chemical analysis and NMR studies, the repeating unit of the polymer was deduced to be a branched hexasaccharide with the structure shown. [formula: see text]
The complete structure of the lipooligosaccharide (LOS) from Neisseria meningitidis strain NMB (serotype 2b:P1.2,5), a serogroup B cerebrospinal fluid isolate, was determined. Two oligosaccharide (OS) fractions and lipid-A were obtained following mild acid hydrolysis of the LOS. The structures in these fractions were determined using glycosyl composition and linkage analyses, N spectroscopy and mass spectrometry. One oligosaccharide fraction (OS1) consists of a molecule having a glycosyl sequence identical to that previously reported for the LOS from immunotype L2 N. meningitidis [A. Gamain, M. Beurret, F. Michon, J.-R. Brisson, and H.J. Jennings, J. Biol. Chem.,267,(112) 922-925] i.e., a lacto-N-neotetraose is attached to heptose I (Hep I), with terminally linked N-acetylglucosaminosyl and glucosyl residues attached to Hep II of the inner core. Approximately 70% of this structure is acetylated at O-6 of the terminally linked alpha-N-acetyl-glucosaminosyl residue. As with the L2 structure, the NMB LOS contained phosphoethanolamine (PEA) at O-6 or O-7 of the Hep II residue. The second oligosaccharide fraction (OS2) contains a a mixture of three different molecules, all of which vary from one another in their glycosyl substitution patterns of the Hep II residue. The most abundant molecule in OS2 has a structure identical to that of OSI, i.e., it has the L2 glycosyl sequence. A second molecule (OS2a) lacks the terminal glucosyl residue at O-3 of Hep II; i.e., it has a glycosyl sequence identical to that of the mild acid released oligosaccharide of N. meningitidis immunotype L3, L4, or L7 LOSs. The third molecule (OS2b) is a novel structure that lacks the terminal N-acetylglucosaminosyl residue linked to O-2 of Hep II. Overall, 76% of OS released from NMB LOS has the L2 structure, 15% is OS2a (L3), and 9% is OS2b. A portion (20%) of the molecules in the NMB LOS preparation also contained terminally linked sialic acid attached to O-3 of the lacto-N-neotetraose galactosyl residue, which is also consistent with the L3, or L4 LOS structures. In contrast to the previously reported structure of N. meningitidis lipid-A [V. A. Kulshin, U. Zähringer, B. Linder, C.E. Frasch, C-M. Tsai, B.A. Dmitriev, and E.T Rietschel, J. Bacteriol., 174, (1992)1793-1800], only 30% of the lipid-A from NMB LOS possesses 4'-phosphate. Comparison with the lipid-A of LOS purified from an isogenic acapsulate mutant, M7, revealed that the 4'-position was almost completely occupied with phosphate. These data emphasize the structural heterogeneity of the OS and phosphate substituents of Hep II, and 4'-phosphorylation of lipid-A of meningococcal LOS.
Explore the source record for details and available documents.
Because of the critical role of neutrophils in host defenses, it was hypothesized that stimulation of neutrophil production and function with Filgrastim would improve the outcome of hospitalized patients with community-acquired pneumonia. To test this hypothesis, a randomized, placebo-controlled, multicenter trial of Filgrastim (300 micrograms/day up to 10 days) as an adjunct to antibiotics was conducted for these patients. Outcome measures included time to resolution of morbidity (TRM, a composite measure of temperature, respiratory rate, blood oxygenation, and chest radiograph), 28-day mortality, length of stay, and adverse events. Filgrastim increased blood neutrophils 3-fold, but TRM, mortality, and length of hospitalization were not affected. Treatment, however, accelerated radiologic improvement and appeared to reduce serious complications (e.g., empyema, adult respiratory distress syndrome, and disseminated intravascular coagulation). Filgrastim administration was safe and well tolerated in these patients. Additional trials are needed to establish the value of this approach to treatment of infectious diseases.
A specific and highly potent inhibitor of diguanylate cyclase, the key regulatory enzyme of the cellulose synthesizing apparatus in the bacterium Acetobacter xylinum, was isolated from extracts of etiolated pea shoots (Pisum sativum). The inhibitor has been purified by a multistep procedure, and sufficient amounts of highly purified compound (3-8 mg) for spectral analysis were obtained. The structure of this compound was established as 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1--> 2)-beta-D-glucuronopyranosyl soyasapogenol B 22-O-alpha-D-glucopyranoside. The structure was elucidated on the basis of susceptibility to various enzymes, chemical and spectral methods, such as GC-MS, FAB-MS, and the following types of 2D-NMR: COSY, ROESY, TOCSEY, HMQC, HMBC analyses. An identical or a very similar compound with identical biological activity was also isolated from A. xylinum, strongly suggesting that at least certain aspects of cellulose synthesis in the bacteria and in higher plants may be regulated in a similar manner. The content of this saponin in etiolated plants was about 0.04 mumol (g fresh tissue)-1.
The molecular basis for the resistance of serogroup B Neisseria meningitidis to the bactericidal activity of normal human sera (NHS) was examined with a NHS-resistant, invasive serogroup B meningococcal isolate and genetically and structurally defined capsule-, lipooligosaccharide (LOS)-, and sialylation-altered mutants of the wild-type strain. Expression of the (alpha2-->8)-linked polysialic acid serogroup B capsule was essential for meningococcal resistance to NHS. The very NHS-sensitive phenotype of acapsular mutants (99.9 to 100% killed in 10, 25, and 50% NHS) was not rescued by complete LOS sialylation or changes in LOS structure. However, expression of the capsule was necessary but not sufficient for a fully NHS-resistant phenotype. In an encapsulated background, loss of LOS sialylation by interrupting the alpha2,3 sialyltransferase gene, lst, increased sensitivity to 50% NHS. In contrast, replacement of the lacto-N-neotetraose alpha-chain (Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc) with glucose extensions (GlcN) in a galE mutant resulted in a strain resistant to killing by 50% NHS at all time points. Encapsulated meningococci expressing a Hep2(GlcNAc)-->KDO2-->lipid A LOS without an alpha-chain demonstrated enhanced sensitivity to 50% NHS (98% killed at 30 min) mediated through the antibody-dependent classical complement pathway. Encapsulated LOS mutants expressing truncated Hep2-->KDO2-->lipid A and KDO2-->lipid A structures were also sensitive to 50% NHS (98 to 100% killed at 30 min) but, unlike the wild-type strain and mutants with larger oligosaccharide structures, they were killed by hypogammaglobulinemic sera. These data indicate that encapsulation is essential but that the LOS structure contributes to the ability of serogroup B N. meningitidis to resist the bactericidal activity of NHS.
The production of exopolysaccharide (EPS) was shown to be required for the infection process by rhizobia that induce the formation of indeterminate nodules on the roots of leguminous host plants. In Sinorhizobium meliloti (also known as Rhizobium meliloti) Rm41, a capsular polysaccharide (KPS) analogous to the group II K antigens of Escherichia coli can replace EPS during symbiotic nodule development and serve as an attachment site for the strain-specific bacteriophage phi16-3. The rkpA to -J genes in the chromosomal rkp-1 region code for proteins that are involved in the synthesis, modification, and transfer of an as-yet-unknown lipophilic molecule which might function as a specific lipid carrier during KPS biosynthesis. Here we report that with a phage phi16-3-resistant population obtained after random Tn5 mutagenesis, we have identified novel mutants impaired in KPS production by genetic complementation and biochemical studies. The mutations represent two novel loci, designated the rkp-2 and rkp-3 regions, which are required for the synthesis of rhizobial KPS. The rkp-2 region harbors two open reading frames (ORFs) organized in monocistronic transcription units. Although both genes are required for normal lipopolysaccharide production, only the second one, designated rkpK, is involved in the synthesis of KPS. We have demonstrated that RkpK possesses UDP-glucose dehydrogenase activity, while the protein product of ORF1 might function as a UDP-glucuronic acid epimerase.
The treatment of metastatic breast cancer involves the sequential selection and delivery of hormonal therapies and cytotoxic chemotherapies. The available therapies for metastatic breast cancer are rarely curative, although high rates of response and modest prolongation of survival may be achieved in association with varying degrees of treatment-related toxicity. Therefore, the selection of appropriate therapy requires a reasoned consideration of the likelihood of benefit from therapy balanced with the impact of therapy on the patient's quality of life. Several instruments have been developed to measure quality of life in cancer patients, but none has been universally accepted, and they require time and resources to administer. Few randomized clinical trials have incorporated quality of life assessments. Thus, the clinician must balance antitumor activity, performance status, and the usual toxicity measures, (e.g., nausea, myelosuppression, asthenia) as surrogates for quality of life associated with each specific therapy. Studies have confirmed the clinical impression that antitumor activity of treatment generally correlates with quality of life outcome. The hormonal therapies have the quality of life advantages of limited and non-threatening acute toxicity, rare chronic toxicity, need for infrequent visits to health care providers, oral administration, and, in appropriately selected patients, response and duration of response rates equivalent to those of the cytotoxic agents. A number of cytotoxic agents have activity in the treatment of metastatic breast cancer. Although the active single agents differ substantially in their toxicity profiles, the dose-limiting toxicity is usually myelosuppression. Recently, several agents with substantial activity against breast cancer have become available, including the taxanes (paclitaxel and docetaxel), vinorelbine, and gemcitabine. Oral formulations of vinorelbine are being studied that may provide the additional advantages of not requiring intravenous access, requiring fewer visits to the health care professional, and providing patients with a greater sense of control of their treatment.
Five absorption features are reported at wavelengths of 3.4, 3.88, 4. 05, 4.25, and 4.57 micrometers in the surface materials of the Galilean satellites Callisto and Ganymede from analysis of reflectance spectra returned by the Galileo mission near-infrared mapping spectrometer. Candidate materials include CO2, organic materials (such as tholins containing C(triple bond)N and C-H), SO2, and compounds containing an SH-functional group; CO2, SO2, and perhaps cyanogen [(CN)2] may be present within the surface material itself as collections of a few molecules each. The spectra indicate that the primary surface constituents are water ice and hydrated minerals.
BACKGROUND: The authors previously reported a statistically significant effect of psychosocial intervention on survival time of women with metastatic breast carcinoma. In this study, the authors investigated whether this effect could be explained by differences in the medical treatment patients received subsequent to their group participation or differences in causes of death. METHODS: Of the original 86 study participants, medical treatment charts for 61 and death certificates for 83 were available for further analysis. The authors reviewed the course of the medical treatment they received subsequent to their entry into the randomized psychotherapy trial. RESULTS: Although there were no statistically significant differences with regard to chemotherapy and hormone therapy between the control and treatment groups, women in the control group tended to have received more adrenalectomies, although this procedure did not account for the difference in survival time between the control group and the treatment group. Furthermore, women in the control group developed more bone and lung metastases than the women in the treatment group. CONCLUSIONS: Differences in disease course between the control and treatment groups appeared to be independent of any differences in medical treatment received.
The structure was determined for the capsular polysaccharide (CPS) isolated from a swarming strain of Proteus vulgaris, CP2-96, which was obtained from the spleen of an infected mouse. The CPS was extracted from the cell pellet by hot water, precipitated with ethanol, and further purified by gel-permeation chromatography. The structure was established by glycosyl composition and linkage analyses, and by NMR spectroscopy. The sequence of the glycosyl residues was determined by a NOESY experiment. The CPS is composed of a tetrasaccharide repeating unit with the following structure: OAc [symbol: see text] 4 -->4)-beta-D-Glcp-(1-->3)-beta-D-GalpNAc-(1-->2)-alpha-D-Glcp-(1-->4)-al pha- D-GlcpA-(1-->.
The advent of crack cocaine has changed the face of acute cocaine intoxication. Repeated doses of highly concentrated, rapidly delivered drug can give rise to an array of potentially fatal cardiovascular, neurologic, and respiratory complications.
Mice (Mus musculus) captured in henhouses were assessed for the presence of salmonellae in spleens. Of 621 and 526 spleens cultured during the first and second years of collection, 25.0 and 17.9%, respectively, were positive for Salmonella enterica serovar Enteritidis. Contaminated eggs were cultured from nine houses during the first year of sampling, and for eight of these houses, serovar Enteritidis was recovered from the spleens of mice. Rank sum statistical analysis of positive mouse spleens indicated that three overlapping bacterial populations were present. This pattern of infection was repeated when lipopolysaccharide (LPS) variants were used to infect chicks, and the worst infections were associated with isolates producing high-molecular-weight (HMW) LPS. Mouse isolates were capable of producing unprecedented amounts of HMW LPS as indicated by compositional analysis of six isolates that swarmed across 2% agar, which is a type of bacterial migration dependent upon production of HMW LPS. It is suggested that serovar Enteritidis cultured from the spleens of mice caught on farms will detect strains that are enhanced in their ability to contaminate eggs, in part because they are able to produce HMW LPS.
The lipopolysaccharide (LPS) of Salmonella enteritidis has been implicated as a virulence factor of this organism. Therefore, the LPS from a stable virulent isolate, SE6-E21, was compared with that from an avirulent isolate, SE6-E5. The LPSs were extracted, and the high-molecular-weight (HMW) LPS was separated from the low-molecular-weight (LMW) LPS for both isolates. Both the HMW and LMW LPSs were characterized by glycosyl composition and linkage analyses. Immunochemical characterization was performed by Western blotting using factor 9 antiserum and using S. typhimurium antiserum which contains factors 1, 4, 5, and 12(2). In addition, the polysaccharides released by mild acid hydrolysis were isolated and subjected to hydrolysis by bacteriophage P22, which contains endorhamnosidase activity. The resulting oligosaccharides were purified by using Bio-Gel P4 gel permeation chromatography and characterized by nuclear magnetic resonance spectroscopy, fast atom bombardment mass spectrometry (FAB-MS), tandem MS-MS, and matrix-assisted laser desorption time of flight MS. The results show that the HMW LPS O-antigen polysaccharides from both isolates are comprised of two different repeating units, -[-->2)-[alpha-Tyvp-(1-->3)]beta-D-Manp-(1-->4)-alpha-L-R hap-(1-->3)-alpha-D-Galp-(1-->]- (structure I) and [-->2)-[alpha-Tyvp-(1-->3)]beta-D-Manp-(1-->4)-alpha--L-R hap-(1-->3)-[alpha-D-Glcp-(1-->4)]alpha-D-Galp-(1-->]- (structure II). The LMW LPSs from both isolates contains truncated O-antigen polysaccharide which is comprised of only structure I. In the virulent SE6-E21 isolate, the HMW LPS has a structure I/II ratio of 1:1, while in the avirulent SE6-E5 isolate, this ratio is 7:1. While the 7:1 ratio represents the published level of glucosylation for S. enteritidis LPS as well as for S. enteritidis LPS purchased from Sigma Chemical Co., the 1:1 ratio found for the virulent SE6-E21 is identical to the high level of glucosylation reported for S. typhi LPS. Thus, the LPS from the virulent SE6-E21 isolate produces an S. typhi-like LPS. Furthermore, the amount of O-antigen polysaccharide in SE6-E21 was twice that in SE6-E5.
The first complementation unit of the fix-23 region of Rhizobium meliloti, which comprises six genes (rkpAB-CDEF) exhibiting similarity to fatty acid synthase genes, is required for the production of a novel type of capsular polysaccharide that is involved in root nodule development and structurally analogous to group II K antigens found in Escherichia coli (G. Petrovics, P. Putnoky, R. Reuhs, J. Kim, T. A. Thorp, K. D. Noel, R. W. Carlson, and A. Kondorosi, Mol. Microbiol. 8:1083-1094, 1993; B. L. Reuhs, R. W. Carlson, and J. S. Kim, J. Bacteriol. 175:3570-3580, 1993). Here we present the nucleotide sequence for the other three complementation units of the fix-23 locus, revealing the presence of four additional open reading frames assigned to genes rkpGHI and -J. The putative RkpG protein shares similarity with acyltransferases, RkpH is homologous to short-chain alcohol dehydrogenases, and RkpJ shows significant sequence identity with bacterial polysaccharide transport proteins, such as KpsS of E. coli. No significant homology was found for RkpI. Biochemical and immunological analysis of Tn5 derivatives for each gene demonstrated partial or complete loss of capsular polysaccharides from the cell surface; on this basis, we suggest that all genes in the fix-23 region are required for K-antigen synthesis or transport.