Linking basic, clinical, and social sciences.
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Clinical Medicine↗
Biomedical subjects
M K Wolf
Publications and source records attributed to M K Wolf.
Phase II evaluation of didemnin B in hormonally refractory metastatic prostate cancer. A Southwest Oncology Group study.
Didemnin B, a dipsipeptide isolated from the Caribbean tunicate Trididemnum with antitumor and antiviral activity was evaluated in a phase II trial in the treatment of metastatic, hormonally refractory adenocarcinoma of the prostate. Thirteen patients were treated with didemnin B at 3.5 mg/m2 and 20 patients were treated at 6.3 mg/m2 intravenously every 28 days. Response was assessed every 8 weeks. Of 32 evaluable patients there was one partial response for an overall response rate of 3% (95% confidence interval of 0.1-16%). The most common toxicities were nausea, vomiting, and diarrhea. Serious cardiac and pulmonary toxicities were also noted. This drug does not appear to warrant further evaluation in this disease as a single agent.
Adenocarcinoma↗
Colonization factors of diarrheagenic E. coli and their intestinal receptors.
While Escherichia coli is common as a commensal organism in the distal ileum and colon, the presence of colonization factors (CF) on pathogenic strains of E. coli facilitates attachment of the organism to intestinal receptor molecules in a species- and tissue-specific fashion. After the initial adherence, colonization occurs, and the involvement of additional virulence determinants leads to illness. Enterotoxigenic E. coli (ETEC) is the most extensively studied of the five categories of E. coli that cause diarrheal disease, and has the greatest impact on health worldwide. ETEC can be isolated from domestic animals and humans. The biochemistry, genetics, epidemiology, antigenic characteristics, and cell and receptor binding properties of ETEC have been extensively described. Another major category, enteropathogenic E. coli (EPEC), has virulence mechanisms, primarily effacement and cytoskeletal rearrangement of intestinal brush borders, that are distinct from ETEC. An EPEC CF receptor has been purified and characterized as a sialidated transmembrane glycoprotein complex directly attached to actin, thereby associating CF-binding with host-cell response. Three additional categories of E. coli diarrheal disease, their colonization factors and their host cell receptors, are discussed. It appears that biofilms exist in the intestine in a manner similar to oral bacterial biofilms, and that E. coli is part of these biofilms as both commensals and pathogens.
Adhesins, Bacterial↗
Phase II trial of CHIP for the treatment of advanced, hormonally refractory carcinoma of the prostate. A Southwest Oncology Group Study.
CHIP, a second generation analogue of cisplatin, was subjected to a Phase II trial for the treatment of advanced, hormonally refractory carcinoma of the prostate. Forty-six patients were treated with CHIP 300 mg/m2 intravenously every 4 weeks. Evaluations for tumor response were done after three cycles of therapy. Among 40 evaluable patients there were no complete responses, but there were 6 partial responses for an overall response rate of 15% (95% confidence interval of 5.7 to 29.8%). The median time to response was 2.4 months and the median progression-free survival was 4.1 months. Median survival was 8.4 months. The most common toxicities were hematologic and gastrointestinal. While CHIP can be administered on an outpatient basis, its response rate for prostatic carcinoma appears to be similar to that of cisplatin.
Adenocarcinoma↗
A phase II trial of continuous-infusion recombinant interleukin-2 in patients with advanced renal cell carcinoma: a Southwest Oncology Group study.
A multicenter, phase II trial of continuous-infusion interleukin 2 (IL-2) was done in the Southwest Oncology Group to evaluate the efficacy and safety of this treatment in a broad-based population of patients with metastatic renal-cell carcinoma. Forty-seven patients from 11 different institutions were entered in this study, with 43 eligible. Two technically ineligible patients who received treatment and for whom records are available are included in the data analysis. Thus, there are 45 analyzable patients. Of these patients, performance status was 0 in 58% and 1 in 42%. Thirty-one patients had a prior nephrectomy, and 12 patients had received prior therapy. IL-2 was initially given at a dose of 4.5 x 10(6) Roche U/m2/day, 4 days a week, for 4 weeks in a row, followed by a 3-week rest period. Because of the difficulty in obtaining reimbursement for the hospitalization required on the days of IL-2 administration, after 10 patients had been entered, the treatment regimen was changed to 6 x 10(6) Roche U/m2/day for 4 days as an inpatient, followed by 2 weeks of potential outpatient treatment at a dose of 3 x 10(6) Roche U/m2/day for 4 days each week. This was followed by a 2-week rest period. Within the 45 analyzable patients, there were 0 complete responses and 6 partial responses, for a response rate of 13% (95% confidence interval 5.1-27%). Responses occurred in lung metastases, nodal disease, and in one patient with bone metastases and the primary kidney tumor. Response durations were 1 month, 1 month, 14+ months, 19 months, 26+ months, and 27 months. Of 12 patients with a nephrectomy and only lung metastases, 4 showed partial responses. Medial survival for all analyzable patients is 15 months (95% confidence interval 8-20 months). Toxicity was significant, with nausea and vomiting, diarrhea, fever and chills, dermatologic changes, and fatigue the most frequent. There were 18 instances of grade 4 toxicity, with the most common grade 4 toxicity, respiratory, found in 8 patients. There were two early deaths of probable heart-related causes while receiving treatment. A continuous-infusion IL-2 regimen that allows some potential outpatient treatment shows effectiveness and toxicity similar to that in other multicenter IL-2 infusion trials and high-dose intravenous bolus regimens.
Adult↗
Cytoskeleton in myelin-basic-protein-deficient shiverer oligodendrocytes.
Production of CNS myelin by oligodendrocytes requires the regulated synthesis and assembly of cytoskeletal components. However, the molecular signals that mediate this process are not known. Here we use the shiverer mutant mouse, which is missing a large segment of the myelin basic protein (MBP) gene, to investigate the possible role in cytoskeletal assembly of an MBP gene product or of other myelin components whose expression may be linked to that of MBP. In axon-free cultures, we find that approximately half of shiverer oligodendrocytes have enlarged cell bodies, abnormal processes and fail to elaborate extensive membrane sheets. In those membrane sheets that are elaborated by shiverer oligodendrocytes, microtubular structures are abnormal in size and distribution. Additionally, 2',3'-cyclic nucleotide 3'-phosphohydrolase and microfilaments are not colocalized with microtubular structures as they would be in mature wild-type membrane sheets. These observations suggest that an MBP gene product has a direct or indirect role in regulating various aspects of cytoskeleton assembly in wild-type oligodendrocytes. In the absence of this signal, oligodendrocytes apparently do not normally assemble cytoskeleton; this may be one important basis for the abnormal morphology of intact shiverer CNS.
2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
Jimpy 4J: a new X-linked mouse mutation producing severe CNS hypomyelination.
This study describes a new sex-linked myelin mutation in the mouse, jimpy 4J (Plpjp-4J), located in or very close to the proteolipid protein (Plp) gene. The Plpjp-4J/Y phenotype includes tremor, seizures, death during the 4th postnatal week, and the most severe central nervous system hypomyelination yet described in any mouse carrying a single myelin mutation. The few myelin sheaths are present in early myelinating areas where they form clusters of thin, usually loosely wrapped membranes which show several variations of morphology at their extracellular leaflets. Numbers of mature oligodendrocytes are sharply reduced; pycnotic glial nuclei and foamy cells are numerous. Astrocytosis is a prominent feature. No PLP protein is detected by immunoblotting in Plpjp-4J/Y brain but in spinal cord a faint band is present. Myelin basic protein and characteristic myelin lipids are also sharply reduced in both brain and spinal cord. Despite the qualitative similarity of the phenotypes reported in these and previous studies, DNA analysis demonstrate that Plpjp-4J is not a recurrence of the well known Plp mouse mutations jimpy (Plpjp) or myelin synthesis deficiency (Plpjp-msd).
Animals↗
Myelin basic protein mediates extracellular signals that regulate microtubule stability in oligodendrocyte membrane sheets.
Treatment of cultured oligodendrocytes with a monoclonal antibody to galactocerebroside (GalC) triggers a cascade of events including the redistribution of membrane surface GalC over internal domains of MBP and loss of microtubular structures within the sheets (Dyer and Benjamins: J Neurosci 8:4307-4318, 1988; Dyer and Benjamins: J Neurosci Res 24:212-221, 1989). In this report, wild type and myelin basic protein (MBP)-deficient shiverer oligodendrocytes were used to study the possible relationships between these events, and specifically to determine if MBP mediates signals which destabilize microtubular assemblies in cultured oligodendrocytes. We now show that MBP and GalC, which are both initially Triton X-100 soluble, become Triton X-100 insoluble following anti-GalC binding and anti-GalC:GalC complex redistribution, suggesting that the surface anti-GalC: GalC complexes become associated with cytoplasmic MBP. Mediation of the signaling event by MBP is further demonstrated by 1) a decreased phosphorylation of MBP in wild type oligodendrocytes after antibody binding, and 2) the absence of responses, such as GalC redistribution and microtubule loss, in MBP-deficient shiverer oligodendrocytes treated with anti-GalC. Continuous activation of the GalC/MBP pathway for 7 days in wild type oligodendrocytes results in enlarged cell bodies and production of numerous microprocesses, a morphology that is similar to MBP-deficient shiverer oligodendrocytes. A second signaling pathway which produces an opposite effect, i.e., the stabilization and apparent up-regulation of microtubular structures in cultured oligodendrocyte membrane sheets, remains functional in shiverer oligodendrocytes. Thus, MBP appears to be important for mediating extracellular signals that cause a loss of microtubular structures in oligodendrocyte membrane sheets and abnormal morphology.
Animals↗
A case of diarrhea, bacteremia, and fever caused by a novel strain of Escherichia coli.
A nonenteropathogenic strain of Escherichia coli from a patient with diarrhea and bacteremia possessed the attaching-effacing eae gene, was invasive in the gentamicin invasion assay, and expressed two types of pili and K1 antigen. This unique combination places the strain in a new category of attaching-effacing E. coli.
Bacteremia↗
Characterization of enterotoxigenic Escherichia coli isolated from U.S. troops deployed to the Middle East.
Enterotoxigenic Escherichia coli (ETEC) was a common cause of traveler's diarrhea in U.S. soldiers in the Middle East in 1989 and 1990. To determine which bacterial components would be useful in a vaccine, potential protective antigens (toxin, colonization factor antigen [CFA], and serotype) from 189 ETEC isolates were examined. Nearly half of the isolates expressed both ETEC toxins, 39% had only heat-stable enterotoxin (ST), and 17% had heat-labile enterotoxin (LT). CFA/I was the least common colonization factor antigen (11%), CFA/II was common (34%), as was CFA/IV (31%), and 24% expressed none of these CFAs. Fifty-seven O:H serotypes were found. Serotype O6:H16 was the most common, occurring in 29% of the ETEC isolates, usually with LT-ST and CFA/II. Generally, CFA/II was associated with expression of both toxins, CFA/IV was associated with expression of ST, and none of the CFAs was routinely found with LT. We conclude that ETEC from soldiers in the Middle East expressed a variety of antigens and that an effective vaccine will require multiple protective antigens.
Antigens, Bacterial↗
Quantitative differences between homozygous 'USA' and 'Swiss' mld mutant mice.
Parallel developmental studies of central nervous system myelin proteins and morphology (postnatal days 15-118; P15-118) confirm qualitative similarities but substantial quantitative differences between homozygous mld mice with Billings-Gagliardi and Wolf's 'USA' versus Matthieu's 'Swiss' genetic backgrounds. The USA mld/mld have fewer convulsions and significantly longer life span. While whole-brain homogenates from both Swiss and USA mld/mld show increases in myelin basic protein (MBP) and in 2',3'-cyclic nucleotide 3'-phosphohydrolase specific activity with age, at P50 and older the levels of both proteins are approximately twice as high in the Swiss. The number of optic nerve axons myelinated is always greater in Swiss mld/mld, and they have approximately twice as many myelin sheaths showing any apposition of cytoplasmic membrane faces (the location of the major dense line in normal myelin), except at the youngest age. Evidence is presented which suggests that these quantitative differences between Swiss and USA mld stocks most likely reflect different regulatory genes influencing the expression of the same (mld) allele, rather than the presence of a different allele at the MBP locus.
Aging↗
Shiverer jimpy double mutant mice. V. Correlation of genotype and myelin proteins.
We have reexamined the levels of myelin basic protein (MBP) and proteolipid protein (PLP) in the brains of mice bred to carry both the shi/shi and jp/Y hypomyelination defects. The genotype of each putative double mutant was confirmed by direct DNA analysis: shi/shi by Southern blot analysis, and jp/Y by restriction enzyme analysis of polymerase chain reaction-amplified fragments. MBP and PLP levels were assessed by immunoblotting. All putative double mutants were found to be shi/shi. However, examination of the PLP locus revealed both jp and wild-type genotypes, the latter produced by an expected crossover. Animals proven to be shi/shi*jp/Y had no detectable MBP or PLP; those proven to be shi/shi*+/Y (the crossover) had no MBP but had PLP. These results differ from an earlier report of both MBP and PLP in the brains of presumed shi*jp animals.
Animals↗
Myelination requirements of central nervous system glia in vitro: statistical validation of differences between glia from adult and immature mice.
Glia from adult optic nerve, like those from immature nerve, have been shown to colonize and myelinate cerebellar axons in combined cultures. Preliminary experiments suggested, however, that the glia from adults might require the added nutrients and/or chemical signals present in a serum and embryo extract containing medium to produce myelin, whereas glia from immature animals could form myelin in a chemically defined medium described by Hendelman et al. (1985). This observation demanded rigorous confirmation, since it depended on the meaning of a negative result (the absence of myelin), which could be produced by many factors other than the composition of the medium in this complex culture system. Here we report an extensive series of experiments, with controls for all other factors, that provide unquestionable statistical validation of the additional myelination requirements of the glia from adult nerves. The cultures can now be used to identify these required substances, which may be limiting factors for central nervous system myelin regeneration in situ.
Aging↗
Quaking*jimpy double mutant mice: additional evidence for independence of primary deficits in jimpy.
Mice which have the genotype qk/qk*Tajp/Y, and therefore simultaneously express both the quaking (qk) and jimpy (jp) mutations, have CNS white matter morphology intermediate between qk and jp with respect to amount of myelin, myelin structure, and oligodendrocyte number. The level of myelin basic protein in the CNS is also intermediate; however, myelin proteolipid protein (PLP) is virtually absent. Thus in the qk/qk*Tajp/Y double mutant mouse the PLP deficit is as severe as in jp alone but the oligodendrocyte survival deficit (reflected in number and myelin production) of jp alone is rendered less severe. The observation that these two cardinal deficits of the jp mutation can be independently altered in double mutant combinations is consistent with our previous suggestion that the PLP genetic locus may encode at least two independently regulated primary gene functions: a structural protein and signal influencing oligodendrocyte behavior.
Animals↗
Implications of double mutant phenotypes.
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Animals↗
Cloning of the genes for AF/R1 pili from rabbit enteroadherent Escherichia coli RDEC-1 and DNA sequence of the major structural subunit.
AF/R1 pili on the surface of Escherichia coli RDEC-1 promote attachment of the bacteria to rabbit intestinal brush borders. In order to characterize AF/R1 pili and manipulate their expression, we cloned the genes necessary for AF/R1 expression; determined the size of proteins produced in minicells; located the gene encoding the major structural subunit, named AfrA; and determined the DNA sequence of afrA as well as the sequence of 700 additional nucleotides upstream of afrA. Two contiguous EcoRI fragments spanning 7.9 kilobases were cloned from the 86-megadalton plasmid of RDEC-1 into vector pUC19 to make plasmid pW1. Bacteria carrying pW1 produced AF/R1 pili that were recognized by AF/R1-specific antiserum and promoted adherence of bacteria to brush borders prepared from rabbit intestine. Proteins with a molecular weight of 17,000 (17K proteins), which was the size of AfrA, as well as 15K, 15.5K, 26K, 28K, and 80K proteins were detected in minicells carrying pW1. The gene afrA was located by using an oligonucleotide probe, and its DNA sequence was determined. The DNA sequence of 700 additional nucleotides upstream was determined because this sequence may be important in the regulation of AF/R1 expression.
Amino Acid Sequence↗
Characterization of CS4 and CS6 antigenic components of PCF8775, a putative colonization factor complex from enterotoxigenic Escherichia coli E8775.
PCF8775 is a putative colonization factor complex present on the surface of 10 to 20% of enterotoxigenic Escherichia coli strains and has been reported to be composed of antigen CS6 (morphology undefined) expressed alone or together with either of the rigid fimbrial antigens CS4 and CS5. To better define the individual components of this complex and the determinants of their expression, we prepared antiserum to the PCF8775 complex as it was expressed on prototype strain E8775 and then used the antiserum to identify the subunit structure of the antigens, to study their morphology, and to detect expression of individual components of the complex after transfer of plasmids into laboratory strain HB101. CS4 was purified from strain E8775, confirmed to be fimbrial by electron microscopy, and found to be composed of a 22-kilodalton protein subunit whose N-terminal amino acid sequence (1 to 20) was similar to that of colonization factor antigen I. Transconjugants that express CS6 but not CS4 were obtained by mating prototype strain E8775 with HB101. CS6 expression was mediated by a 61-megadalton plasmid. Expression of CS6 in the transconjugants correlates with expression of a 16-kilodalton cell surface protein. The CS6 antigen was confirmed to be present on the cell surface by immunogold labeling, but its morphology was beyond the limits of resolution by electron microscopy.
Animals↗
Quaking shiverer double mutant mice: morphological phenotypes support possible dual actions of the shiverer locus.
Mice doubly homozygous for the two different hypomyelination mutations, quaking (qk) and shiverer (shi) or shiverer myelin-deficient (shimld) (abbreviations: qk*shi and qk*shimld), both have much less myelin than either single mutant ancestor, myelin morphology resembling shi or shimld rather than qk, and abundant shi-type oligodendrocytic microprocesses. The qk*shimld double mutant differs from qk*shi only in having small amounts of normal or abnormal major dense line, in keeping with the morphologic difference between the shi and shimld single mutants. By contrast, shi*jp and shimld*jp have clearly different morphological phenotypes; unexpectedly the major dense line is present in the CNS myelin of shi*jp but not shimld*jp. When shi and shimld act alone, their different DNA abnormalities produce similar protein abnormalities. We speculate that the two mutations interact with qk at a different, later step of DNA expression than they interact with jp. In the interaction with qk, the similar proteins produce similar morphologies. In the interaction with jp, the different DNAs are somehow caused to produce protein differences that are reflected in different morphologies. In this study we have observed for the first time a morphological effect of these mutant genes in heterozygous animals. Of particular importance, animals whose genomes combine shi/+ or shimld/+ with qk/qk produce qk-type, compacted myelin but abundant shi-type oligodendrocyte microprocesses. We consider this as evidence that both shi and shimld have two effects: non-production of a normal structural protein, myelin basic protein, and production of an abnormal protein which perturbs the cytogogic function we postulate to be normally exercised by the myelin basic protein gene.
Animals↗