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J W Taylor

Publications and source records attributed to J W Taylor.

At least 55 records · Page 3Linked to original sources
PubMed1997

The ultrastructure of skin from a patient with mucopolysaccharidosis IIID.

Mucopolysaccharidosis IIID (MPS-IIID) is the rarest of the MPS-III syndromes. It is caused by deficient activity of lysosomal N-acetylglucosamine-6-sulfatase (G6S). To date, the clinical and biochemical features of seven patients with MPS-IIID have been reported, but no biopsy or autopsy findings have been described. The purpose of this report is to define the ultrastructure of affected cells seen in a skin biopsy from a 14-year-old boy. The child presented with progressive mental deterioration, hyperactivity and mild to moderate dysmorphism. The diagnosis of a mucopolysaccharidosis was suggested, but the initial urine analyses were negative for elevated mucopolysaccharides, and only the third analysis showed abnormal excretion of heparan sulfate. Because of the diagnostic difficulties posed by this case, a skin biopsy was performed for morphological and biochemical studies. Numerous vacuoles were noted in Schwann cells, fibroblasts, smooth muscle cells, eccrine gland and ductal epithelium in resin-embedded sections stained with toluidine blue. Ultrastructurally, many lysosomes were distended with abundant, fibrillar material. Occasionally, lamellated membranous structures were present within the same lysosomes. These findings are consistent with those seen in other forms of MPS, in which the lysosomal storage occurs predominantly, but not exclusively, in mesenchymal cells. Furthermore, deficient activity of G6S was confirmed in cultured skin fibroblasts. This study demonstrates that electron microscopy of skin biopsies is a useful method for identification of patients with clinical features of MPS-IIID whether or not heparan sulfaturia is present.

Adolescent↗
PubMed1997

Molecular markers reveal differentiation among isolates of Coccidioides immitis from California, Arizona and Texas.

Coccidioides immitis causes coccidioidomycosis, a fungal disease of both immuno-compromised and otherwise healthy people; it is capable of causing large epidemics and the disease is often refractory to chemotherapy. To quantify the magnitude of population differentiation and estimate levels of gene flow in C. immitis, multilocus genotypes were scored for 20-25 clinical isolates from each of Bakersfield (California), Tucson (Arizona), and San Antonio (Texas). The molecular markers used were PCR products with polymorphic restriction endonuclease sites, found and characterized in a previous study of the Tucson population. The data show very highly significant differences in allele frequencies between all three populations, and suggest very low levels of migration between populations. One isolate in the San Antonio sample was an outlier, showing the California-specific allele at all four of the loci distinguishing the two populations, and subsequent inquiries indicated that the infection had indeed been acquired in California. Thus, genetic information can be used to infer the geographical origin of a fungal infection.

Arizona↗
PubMed1997

Angiotensinogen gene expression in adipose tissue: analysis of obese models and hormonal and nutritional control.

Synthesis of angiotensin II (ANG II) has recently been described in adipose cells and has been linked to regulation of adiposity. Angiotensinogen (AGT), the substrate from which ANG II is formed, was previously shown to be elevated in adipose tissue of obese (ob/ob and db/db) mice and regulated by nutritional manipulation. It is unknown, however, whether overexpression of adipose AGT can be extended to other models of obesity and whether hormonal and/or nutritional factors directly regulate AGT expression in adipocytes. We investigated these possibilities by analyzing AGT mRNA levels in adipose tissue of obese Zucker rats, viable yellow (Avy) mice, and humans and by treating 3T3-L1 adipocytes with insulin, glucose, and a beta-adrenergic agonist. We demonstrate that AGT mRNA is decreased by approximately 50 and 80%, respectively, in adipose tissue of obese vs. lean Zucker rats and Avy mice. We also report that AGT is expressed at variable levels in human adipose tissue. Finally, we show that AGT mRNA is upregulated by insulin and downregulated by beta-adrenergic stimulation in adipocytes.

3T3 Cells↗
PubMed1997

Human mucopolysaccharidosis IIID: clinical, biochemical, morphological and immunohistochemical characteristics.

Mucopolysaccharidosis IIID (MPS IIID) is one of the rarest of the MPS-III syndromes. To date, the clinical manifestations of 10 patients have been reported, the deficient N-acetylglucosamine 6-sulfatase (G6S) enzyme has been purified, and the G6S gene has been cloned, sequenced and localized. However, morphological manifestations of this condition have not been reported and the pathogenesis of the severe neurological deficits remains an enigma. In this paper we describe and correlate the clinical, biochemical and pathological observations for 2 cases of MPS IIID. We used monoclonal antibodies against heparan sulfate (HS) and GM2-ganglioside, thin layer chromatography, mass spectrometry, and morphological techniques to demonstrate the nature and the distribution of the uncatabolized substrates. The majority of the cells in various tissues showed morphological changes expected with lysosomal storage of HS. The central nervous system (CNS) was most severely affected because of the secondary storage of GM2 and GM3 gangliosides in addition to the primary accumulation of HS. The extent as well as the distribution of the diverse storage materials varied within and among different neurons as observed in MPS-III A, B, and C syndromes. This study supports the hypothesis that the neurological dysfunction and neurodegeneration common to the Sanfilippo syndromes is, in part, due to the secondary metabolic perturbations induced by HS accumulation.

Adolescent↗
PubMed1996

Molecular markers reveal cryptic sex in the human pathogen Coccidioides immitis.

Coccidioides immitis, cause of a recent epidemic of "Valley fever" in California, is typical of many eukaryotic microbes in that mating and meiosis have yet to be reported, but it is not clear whether sex is truly absent or just cryptic. To find out, we have undertaken a population genetic study using PCR amplification, screening for single-strand conformation polymorphisms, and direct DNA sequencing to find molecular markers with nucleotide-level resolution. Both population genetic and phylogenetic analyses indicate that C. immitis is almost completely recombining. To our knowledge, this study is the first to find molecular evidence for recombination in a fungus for which no sexual stage has yet been described. These results motivate a directed search for mating and meiosis and illustrate the utility of single-strand conformation polymorphism and sequencing with arbitrary primer pairs in molecular population genetics.

Base Sequence↗
PubMed1996

Human pathogeneic fungi and their close nonpathogenic relatives.

In order to understand the relationships between human pathogenic fungi and their close, nonpathogenic relatives, we compared small-subunit ribosomal DNA sequences among four closely related pathogens, Histoplasma capsulatum, Blastomyces dermatitidis, Trichophyton rubrum, and Coccidioides immitis, and seven nonpathogenic fungi expected on morphological grounds to be their nearest relatives. We sequenced small-subunit RNA genes from these fungi and used both genetic distance and parsimony algorithms to evaluate their evolutionary relationships to the pathogens. We show that the pathogens are not a monophyletic group, but rather are interspersed among nonpathogenic fungi; thus it is likely that pathogenicity has arisen multiple times within this group. The saprobic fungi Chrysosporium parvum and Uncinocarpus reesii are the closest known relatives of the highly pathogenic Blastomyces dermatitidis and Coccidioides immitis, respectively, and thus may be considered primary candidates for model systems for researchers studying these fungi. The branching order suggests that the conidium (asexual spore) types aleurioconidia and arthroconidia do not define monophyletic groups and may be less distinct than their names suggest. Fungi with a complete life cycle are shown to have closest relatives that lack a known sexual cycle. Such analyses offer a means by which the sexual and asexual fungi could be integrated into a single classification system.

Base Sequence↗
PubMed1996

Phylogenetic origins of the asexual mycorrhizal symbiont Cenococcum geophilum Fr. and other mycorrhizal fungi among the ascomycetes.

The phylogenetic relationship of the asexual mycorrhizal fungus Cenococcum geophilam Fr. among sexual ascomycetes was examined by phylogenetic analysis of nucleotide sequence data from the nuclear small subunit (18S) ribosomal RNA genie region. A specific focus of this study was to test the hypothesis that the genus Elaphomyces is the closest sexual relative of C. geophilum. Thus nucleotide sequence data of five C. geophilum isolates, three Elaphomyces species, and 44 additional genera of ascomycetes were included in the phylogenetic analyses. The percentage of similarity among the 18S rDNA sequences of the C. geophilum isolates examined was 99.8 to 100%, indicating that C. geophilum is monophyletic. Percent similarity of nucleotide sequence among the three Elaphomyces species was also high and ranged from 99.4 to 99.5%. DNA parsimony and distance analysis of the sequence data separated these 2 genera on distant clades when sequence from 44 additional genera of ascomycetes was included. Parsimony and distance analyses positioned C. geophilum as a basal, intermediate lineage between the two Loculoascomycete orders, the Pleosporales and the Dothidiales, and strongly supported Elaphomyces to be of Plectomycete origin. Among the sexual Ascomycetes examined, which included representative taxa from four classes of filamentous Ascomycetes (Plectomycetes, Pyrenomycetes, Discomycetes, and Loculoascomycetes), no close sexual relative to C. geophilum was identified. At least four independent lineages of mycorrhizal fungi were identified among the ascomycetes examined.

Ascomycota↗
PubMed1996

Insulin increases lipogenic enzyme activity in human adipocytes in primary culture.

Studies with human adipose tissue have demonstrated the presence of key enzymes of fat synthesis. However, long-term regulation of these enzymes has not been reported. To address this issue, we used human adipocytes in primary culture. Human adipose tissue was obtained from abdominal fat of patients undergoing abdominal surgery. Adipocytes were isolated by collagenase digestion and cultured in media supplemented with 1% fetal bovine serum. To evaluate metabolic activity of cultured cells, we assessed the following during the culture: DNA pattern, cell size, glucose consumption and activities for two lipogenic enzymes, fatty acid synthase (FAS) and glycerol-3-phosphate dehydrogenase (GPDH). Analysis of DNA pattern showed that human adipocytes cultured under the above condition did not undergo cell apoptosis. In addition, no significant change in the cell size occurred during 22 d of culture. Glucose consumption by cultured cells was also constant during the culture and was 60% greater in the presence of 10 nmol/L of insulin. Treatment of cultured human adipocytes with insulin for 3-22 d increased GPDH and FAS activity by 60% and 2.8-fold, respectively, compared to cells cultured without insulin. Furthermore, the increase in FAS activity due to insulin treatment was dose dependent and maximal at 10 nmol/L. Our studies show for the first time that human adipocytes can be maintained viable and metabolically active for 2-3 wk in culture. Interestingly, cultured cells remain responsive to insulin. Therefore, this system will allow further characterization of long-term regulation of lipogenesis in human adipocytes and will be useful for developing pharmacological treatments of obesity.

Adipocytes↗
PubMed1996

Clinical isolates of Histoplasma capsulatum from Indianapolis, Indiana, have a recombining population structure.

A sample of 30 clinical isolates of Histoplasma capsulatum was analyzed to determine (i) whether genetic exchange is important in the life cycle of this fungus and (ii) whether distinct subpopulations which correlate with disease severity or host immune status exist. Eleven biallelic molecular markers were developed, with the frequency of the least common allele at each molecular locus ranging from 10 to 50%. Every isolate had a different, unique multilocus genotype. Data analysis indicated that frequent recombination occurs within the Indianapolis, Ind., population. There were no associations between isolates from the immunocompromised population or from those with different clinical manifestations of histoplasmosis.

Genes, Fungal↗
PubMed1995

Structural and conformational requirements for human calcitonin activity: design, synthesis, and study of lactam-bridged analogues.

The conformational and pharmacological effects of the introduction of conformational constraints in the form of i-(i + 4) lactam-bridges in the potential amphiphilic alpha-helical region (8-21) of human calcitonin (hCT) were studied. The following three cyclic hCT analogues were synthesized: cyclo17,21-[Lys17,Asp21]hCT (1), cyclo17,21- [Asp17,Lys21]hCT (2) and cyclo10,14-[Lys10,-Asp14]hCT (3). For their syntheses, solid-phase methodology was used in combination with either direct side chain to side chain cyclization on the solid support or a segment-condensation strategy. Circular dichroism studies in aqueous buffer, pH 7.0, indicated that the conformational effects were different for each lactam bridge introduced. Significant induction of alpha-helical structure was observed only for peptide 3. In contrast, peptide 1 and hCT had similar CD spectra, indicative of mixed disordered and beta-sheet conformations, and peptide 2 had a weaker spectrum consistent with the formation of a more ordered but nonhelical structure. In rat brain receptor binding assays, peptide 2 showed a nearly 80-fold higher potency than hCT or peptides 1 and 3. All three analogues stimulated adenylyl cyclase in the rat kidney membrane at 5-fold lower concentrations than hCT and with similar maximal effects. In vivo hypocalcemic assays, performed in mice by analysis of serum calcium levels 1 h after sc injection, indicated that peptide 2 had similar maximal effects to hCT and was 10-20 times more potent than hCT at doses giving half-maximal effects. In contrast, peptides 1 and 3 were not significantly more potent than hCT. Our findings indicate compatibility of all three lactam bridges and, most probably, also the amphiphilic alpha-helix, with the pharmacological activities of hCT. However, the properties of peptide 2 also suggest that another conformation, possibly a type I beta-turn involving residues 17-20, may play an important role. A multistep mechanism of receptor recognition by hCT that might account for these results is discussed.

Adenylyl Cyclases↗
PubMed1995

Phylogeny of Discomycetes and early radiations of the apothecial Ascomycotina inferred from SSU rDNA sequence data.

We used nucleotide sequences of the small subunit ribosomal genes (SSU rDNA) to examine evolutionary relationships of apothecial ascomycetes (division Ascomycota; class Discomycetes sensu), commonly known as the cup fungi. The apothecial ascomycetes include both lichen-forming and free-living fungi. We sequenced the SSU rDNA from representatives of 10 fungal genera from four orders: Pezizales (Ascobolus lineolatus, Morchella elata agg., Peziza badia); Leotiales (Leotia lubrica, Sclerotinia sclerotiorum); Caliciales (Calicium tricolor, Mycocalicium albonigrum, Sphaerophorus globosus); and Lecanorales (Lecanora dispersa, Porpidia crustulata). Of these, C. tricolor, S. globosus, L. dispersa, and P. crustulata are lichen-forming fungi. Based on parsimony analyses of approximately 1750 aligned nucleotides of their SSU rDNA, we determined a most parsimonious tree (MPT). This hypothesis suggests that the apothecial ascomycetes are a paraphyletic assemblage, basal to other groups of filamentous ascomycetes including representatives of the perithecial fungi and cleistothecial fungi. The most parsimonious tree produced using this dataset supported the monophyly of the orders Pezizales, Leotiales, and Lecanorales. However, there was no support for monophyly of the representative Caliciales; S. globosus had affinities with members of the Lecanorales. This phylogenetic hypothesis recognizes Pezizales as basal and supports Nannfeldt's hypothesis (1932) of a primitive apothecial ascomata with subsequent evolution of perithecial and cleistothecial forms. This MPT provides a foundation for understanding evolution of the ascomycetous fungi.

Ascomycota↗
PubMed1995

Pretreatment regimens for adverse events related to infusion of amphotericin B.

Infusion-related adverse events (IRAEs) such as nausea, vomiting, fever, chills, and thrombophlebitis that are associated with amphotericin B therapy often lead clinicians to prescribe a number of adjunctive pretreatment medications in an attempt to reduce the incidence and severity of these events. The purpose of this study was to determine the incidence of IRAEs during the first week of systemic amphotericin B therapy and to identify pretreatment regimens that are effective in preventing these IRAEs. Three hundred ninety-seven adult inpatients receiving amphotericin B therapy were prospectively monitored, and data regarding IRAEs and pretreatment regimens were collected. Of these patients, 282 (71%) developed at least one IRAE during the first 7 days of therapy. The IRAEs most commonly reported were fever (51% of patients) and chills (28%), followed by nausea (18%), headache (9%), and thrombophlebitis (5%). The most common regimens included diphenhydramine, a corticosteroid, acetaminophen, and heparin, administered alone or in combination with these or other drugs. Overall, common pretreatment regimens were similar in efficacy to no pretreatment in the prevention of IRAEs. Thus empirical premedication for IRAEs associated with amphotericin B cannot be routinely advocated; instead, patients should be treated when symptoms first arise and then premedicated for subsequent amphotericin B infusions.

Acetaminophen↗
PubMed1995

Positions of multiple insertions in SSU rDNA of lichen-forming fungi.

Lichen-forming fungi, in symbiotic associations with algae, frequently have nuclear small subunit ribosomal DNA (SSU rDNA) longer than the 1,800 nucleotides typical for eukaryotes. The lichen-forming ascomycetous fungus Lecanora dispersa contains insertions at eight distinct positions of its SSU rDNA; the lichen-forming fungi Calicium tricolor and Porpidia crustulata each contain one insertion. Insertions are not limited to fungi that form lichens; the lichen ally Mycocalicium albonigrum also contains two insertions. Of the 11 insertion positions now reported for lichen-forming fungi and this ally, 6 positions are known only from lichen-forming fungi. Including the 4 newly reported in this study, insertions are now known from at least 17 positions among all reported SSU rDNA sequences. Insertions, most of which are Group I introns, are reported in fungal and protistan lineages and occur at corresponding positions in genomes as phylogenetically distant as the nuclei of fungi, green algae, and red algae. Many of these positions are exposed in the mature rRNA tertiary structure and may be subject to independent insertion of introns. Insertion of introns, accompanied by their sporadic loss, accounts for the scattered distribution of insertions observed within the SSU rDNA of these diverse organisms.

Base Sequence↗
PubMed1995

Phylogeny and PCR identification of the human pathogenic fungus Penicillium marneffei.

The phylogenetic position of the human pathogenic fungus Penicillium marneffei was assessed from the nucleotide sequences of the nuclear and mitochondrial ribosomal DNA regions. Phylogenetic analysis determined that P. marneffei is closely related to species of Penicillium subgenus Biverticillium and sexual Talaromyces species with asexual biverticillate Penicillium states. Knowledge of the phylogenetic position of P. marneffei facilitated the design of unique oligonucleotide primers, from the nuclear ribosomal DNA internal transcribed spacer region, for the specific amplification of P. marneffei DNA. These primers were successful at selectively amplifying DNA from six isolates of P. marneffei and excluding the other species tested, which included Penicillium subgenus Biverticillium and Talaromyces species and several well-known fungal pathogens, namely, Aspergillus fumigatus, Coccidioides immitis, Histoplasma capsulatum, and Pneumocystis carinii. The primers that we have developed for the specific amplification of P. marneffei have the potential to be incorporated in a PCR identification system which could be used for the identification of this pathogenic agent from clinical material.

Animals↗
PubMed1995

Molecular Phylogenetic classification of fungi.

Phylogenetic classification of fungi based on comparison of ribosomal RNA gene sequences is discussed with emphasis on (i) the place of fungi in all of life, (ii) the relationship of medically important fungi to other fungi including model organisms and, (iii) the integration of sexual and asexual fungi into one classification.

DNA, Ribosomal↗
PubMed1994

External reflection FTIR of peptide monolayer films in situ at the air/water interface: experimental design, spectra-structure correlations, and effects of hydrogen-deuterium exchange.

A Fourier transform infrared spectrometer has been interfaced with a surface balance and a new external reflection infrared sampling accessory, which permits the acquisition of spectra from protein monolayers in situ at the air/water interface. The accessory, a sample shuttle that permits the collection of spectra in alternating fashion from sample and background troughs, reduces interference from water vapor rotation-vibration bands in the amide I and amide II regions of protein spectra (1520-1690 cm-1) by nearly an order of magnitude. Residual interference from water vapor absorbance ranges from 50 to 200 microabsorbance units. The performance of the device is demonstrated through spectra of synthetic peptides designed to adopt alpha-helical, antiparallel beta-sheet, mixed beta-sheet/beta-turn, and unordered conformations at the air/water interface. The extent of exchange on the surface can be monitored from the relative intensities of the amide II and amide I modes. Hydrogen-deuterium exchange may lower the amide I frequency by as much as 11-12 cm-1 for helical secondary structures. This shifts the vibrational mode into a region normally associated with unordered structures and leads to uncertainties in the application of algorithms commonly used for determination of secondary structure from amide I contours of proteins in D2O solution.

Air↗
PubMed1994

Unique oligonucleotide primers in PCR for identification of Cryptococcus neoformans.

On the basis of a comparison of rRNA sequences coding the internal transcribed spacer (ITS) and 5.8S regions of Filobasidiella neoformans, the teleomorph of Cryptococcus neoformans, and members of its most closely related taxa, unique oligonucleotides were designed for the specific amplification of DNA only from C. neoformans. Various combinations of these primers, designated CN4, CN5, and CN6, and the previously described fungal primers ITS1 and ITS2 were tested in PCR for their ability to amplify DNA from 37 strains of C. neoformans and 31 other isolates representing 18 species of yeasts. The combination of primers CN4 and CN5 amplified DNA from both varieties of C. neoformans but from none of the other species tested. Other pairs of primers (namely, CN5-CN6, CN4-ITS1, and CN6-ITS1) amplified DNA only from C. neoformans and from the saprophyte Filobasidiella depauperata, which is the only other member of the genus Filobasidiella. With appropriate controls, these specific oligonucleotides may be used as primers in PCR to identify C. neoformans.

Base Sequence↗