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Biomedical subjects

J C Williamson

Publications and source records attributed to J C Williamson.

17 recordsLinked to original sources
PubMed2005

Initial tree establishment on blocky quarry waste ameliorated with hydrogel or slate processing fines.

Pocket planting reclamation techniques developed in the 1970s for revegetating blocky quarrying waste have met with very limited success, often because the low water-holding capacity of the waste and limited root development within a small volume of planting pocket material result in severe drought mortality. We tested pocket planting approaches for waste tip reclamation at Europe's largest slate quarry, and compared materials for enhancing the continuity of water- and nutrient-holding down into the interior of the waste tip. When small compost-filled pocket planting bags were placed above slate processing fines (SPF) or water absorbent cross-linked polyacrylamide gel ("hydrogel"), tree growth rates increased in comparison with pocket planting bags alone. The SPF significantly improved tree survival especially during severe drought, but survival was not enhanced by the use of hydrogel. The sorption characteristics of hydrogel indicated that its presence may help to reduce nutrient leaching, but that it may have a negative effect on nitrogen availability. A more likely explanation for the poor performance of pure hydrogel is that it did not maintain sufficient available water, because of discontinuities caused by shrinkage and movement of the hydrogel, and/or degradation of water-holding capacity with environmental exposure. However, the root growth observed in the hydrogel treatments suggests that this technique, if adapted to reduce the effects of hydrogel shrinkage by using finer-grade hydrogel, mixing it with other soil-forming material, and reducing its exposure to extremes of temperature or sunlight, might have the potential to improve the growth and survival of trees planted on sites where delivery of heavy materials such as SPF is impractical. Fine mineral processing waste is freely available at active quarries and should be seen as a key resource for reclamation schemes.

Conservation of Natural Resources↗
PubMed2000

Oxacillin-resistant Staphylococcus aureus endophthalmitis after ganciclovir intraocular implant.

PURPOSE: To describe a patient who developed oxacillin-resistant Staphylococcus aureus endophthalmitis after insertion of a ganciclovir intraocular implant. METHOD: Case report. RESULTS: A 42-year-old man with acquired immunodeficiency syndrome (AIDS) and a history of cytomegalovirus retinitis was admitted with right-sided eye pain and decreased visual acuity 10 days after receiving a second ganciclovir intraocular implant in the right eye. A therapeutic vitrectomy, right eye, was performed on the day of admission. A vitreal tap produced frank pus and white, fluffy debris. Cultures of the vitreal fluid grew oxacillin-resistant S aureus, sensitive only to vancomycin, rifampin, and trimethoprim/sulfamethoxazole. The patient was successfully treated with removal of both ganciclovir implants in the right eye and a 4-week course of vancomycin and rifampin. However, the infection left the patient blind in the infected eye. CONCLUSION: Bacterial endophthalmitis is an infrequent but serious complication of the ganciclovir intraocular implant.

AIDS-Related Opportunistic Infections↗
PubMed1999

Stability of cefepime in peritoneal dialysis solution.

OBJECTIVE: To determine the stability of cefepime in peritoneal dialysis solution. DESIGN: Cefepime HCl was added to premade bags of Delflex peritoneal dialysis solution with 1.5% dextrose to produce a cefepime concentration of approximately 100 microg/mL. Peritoneal dialysis solution bags were stored at 4, 25, and 37 degrees C to simulate refrigeration, room temperature, and body temperature, respectively. Samples were drawn at scheduled times up to 336, 168, and 48 hours, respectively, after the addition of cefepime HCl. Cefepime concentrations were measured by HPLC. SETTING: This study was performed at a university-affiliated tertiary care hospital. OUTCOME MEASURE: If the mean concentration of the samples at a given time and condition was >90% of the initial concentration, cefepime was considered stable at that time and condition. RESULTS: The mean HPLC results for samples drawn at each time and condition were all >90%. CONCLUSIONS: Cefepime is stable in peritoneal dialysis solution with dextrose 1.5% for 14 days refrigerated, seven days at room temperature, and 48 hours at 37 degrees C.

Cefepime↗
PubMed1997

Bovine immunodeficiency virus tat gene: cloning of two distinct cDNAs and identification, characterization, and immunolocalization of the tat gene products.

cDNAs encoding the bovine immunodeficiency virus (BIV) transactivator gene (tat) were cloned from virally infected cells and characterized. BIV expresses two distinct tat mRNAs composed of three exons that are derived by alternative splicing. The BIV tat mRNA splice variants encode Tat proteins of 103 (Tat103) and 108 (Tat108) amino acids. The Tat103 coding region is specified only by exon 2, while that of Tat108 is specified by a truncated exon 2 and the first 30 nt of exon 3. Thus, the first 98 amino acids of each Tat are identical, and have amino terminal, cysteine-rich, conserved core, basic, and carboxyl-terminal domains similar to Tats encoded by primate lentiviruses. BIV-infected bovine cells express a 14-kDa phosphorylated Tat protein identical in size to recombinant Tat expressed in bacteria. BIV Tat was shown to localize exclusively in the nucleoli of virally infected and Tat-expressing cells. Reporter gene assays indicated that Tat103 and Tat108 can strongly transactivate the BIV long terminal repeat (LTR) in virally permissive canine Cf2Th and nonpermissive HeLa and mouse NIH 3T3 cells, but not in permissive lapine EREp cells. However, an intact BIV tat gene is required for viral replication in both Cf2Th and EREp cells. Strong LTR activation by BIV Tat requires a TAR (transactivation responsive) element delimited by viral nt +1 to +31 and the Tat basic domain. BIV Tat strongly cross-transactivates the HIV-1 LTR in a TAR-dependent manner in Cf2Th, but not in EREp, HeLa, or NIH 3T3 cells. In contrast, strong, TAR-dependent cross-transactivation of the BIV LTR by HIV-1 Tat could not be demonstrated in any of these cell types. In Cf2Th cells Tat108 effects a moderately stronger transactivation of the BIV LTR than Tat103, indicative of a functional difference in BIV Tat proteins encoded by the mRNA splice variants. The present studies demonstrate that BIV Tat parallels the primate lentiviral Tats in structure and biochemistry but is not interchangeable with the latter.

3T3 Cells↗
PubMed1996

Synthesis and assembly of chimeric human immunodeficiency virus gag pseudovirions.

Expression of the HIV Gag precursor in insect cells by recombinant baculoviruses results in the assembly and budding of noninfectious pseudovirions that resemble immature virus. Three strategies for packaging additional viral epitopes into pseudovirions were examined: coinfection of insect cells with individual baculoviruses encoding separate Gag and Env structural genes, inframe Gag-Env fusion proteins, and Gag-frameshift-Env fusion proteins. Electron microscopy and Western blot analysis indicated that neither the coinfection nor the inframe fusion strategies reliably produced large quantities of structurally stable chimeric pseudovirions. The frameshift fusion method utilized the retroviral Gag-Pol ribosomal frameshift mechanism for the coexpression of Gag and Gag-frameshift-Env fusion proteins. Large quantities of pseudovirions containing both the Gag and Env epitopes were produced in insect cells. Mice inoculated with the Gag-frameshift-Env pseudovirions developed cytotoxic lymphocyte responses to both HIV Gag and Env epitopes. Vaccine and immunotherapeutic applications of chimeric pseudovirions are discussed.

Animals↗
PubMed1995

Diagnostic assay for Helicobacter hepaticus based on nucleotide sequence of its 16S rRNA gene.

Conserved primers were used to PCR amplify 95% of the Helicobacter hepaticus 16S rRNA gene. Its sequence was determined and aligned to those of related bacteria, enabling the selection of primers to highly diverged regions of the 16S rRNA gene and an oligonucleotide probe for the development of a PCR-liquid hybridization assay. This assay was shown to be both sensitive and specific for H. hepaticus 16S rRNA gene sequences.

Animals↗
PubMed1995

Acid-base disorders: classification and management strategies.

Acid-base disorders are common in clinical practice. Simple acid-base disturbances include metabolic acidosis, metabolic alkalosis, respiratory acidosis and respiratory alkalosis. Each can be clearly identified using a common clinical approach. Proper understanding of acid-base disorders requires knowledge of normal physiology. Each of the simple acid-base disorders can be diagnosed by obtaining a good history and performing a physical examination, followed by determinations of electrolyte levels, anion gap and pH. The degree and nature of compensation should then be analyzed. Finally, the ratio of the change in anion gap to the change in serum bicarbonate (delta AG/delta HCO3-) should be determined. When this diagnostic process is applied, proper identification of the disorder can be made and management can be undertaken. Mixed acid-base disorders can also be identified and managed using this method.

Acid-Base Imbalance↗
PubMed1993

Characterization of bovine immunodeficiency virus rev cDNAs and identification and subcellular localization of the Rev protein.

One of the six putative accessory genes of bovine immunodeficiency virus (BIV) is similar to those identified as rev in the human immunodeficiency virus and visna virus genomes. To further analyze the BIV rev gene locus, protein, and function, rev cDNAs were cloned and characterized. BIV rev mRNA is derived from the full-length transcript by multiple splicing events and consists of three exons, including the untranslated leader sequence and two coding exons. BIV rev cDNA was expressed in bacteria and in a mammalian in vitro translation expression system. A 23-kDa Rev protein (p23rev) was immunologically detected in lysates from both systems by using an antiserum made to a synthetic Rev peptide. Recombinant p23rev made in bacteria was purified and used to make a polyvalent antiserum. Antisera to Rev peptide and recombinant p23rev immunoprecipitated p23rev from BIV-infected mammalian cells but not from virions. A mammalian expression vector using the BIV rev cDNA was constructed; p23rev was immunoprecipitated with anti-Rev serum from 32P-labeled lysates of monkey cells transfected with this plasmid, demonstrating that BIV Rev is phosphorylated. Immunofluorescence and immunoelectron microscopy with anti-BIV Rev antisera localized Rev in the nucleus and, particularly, in the nucleoli of BIV-infected cells. In functional studies, the expression of BIV Rev was shown to positively regulate the appearance both of Gag protein, which is translated from the unspliced primary viral transcript, and of singly spliced env mRNA but not that of the multiply spliced tat mRNA. These results demonstrate that BIV Rev activity correlates with the known function of lentivirus Rev proteins.

Amino Acid Sequence↗
PubMed1992

Laboratory monitoring of nutritional status in burn patients.

Most nutrition laboratory testing relies on serum concentrations of ingested nutrients, their coenzymes, proteins, or lipids. Alternatively, functional tests measure a specific physiological process or biochemical reaction. We compared these two approaches to nutritional assessment in intensive-care burn patients, in whom the serum concentrations of transthyretin (prealbumin), albumin, transferrin, carotene, retinol, ascorbic acid, copper, cholesterol, iron, and calcium were all below established reference ranges. In contrast, serum triglyceride concentrations were often above the reference range. Functional tests for thiamin, riboflavin, pyridoxine, and iron (by zinc protoporphyrin/heme ratio) in these patients all showed normal values. Dietary intake, weight trends, and nitrogen balances all indicated that these patients' estimated caloric and protein needs had been met. These findings suggest that static measurements of serum concentrations may be unreliable indicators of nutritional status in burn patients.

Adolescent↗
PubMed1991

Structural femtochemistry: experimental methodology.

The experimental methodology for structural femtochemistry of reactions is considered. With the extension of femtosecond transition-state spectroscopy to the diffraction regime, it is possible to obtain in a general way the trajectories of chemical reactions (change of internuclear separations with time) on the femtosecond time scale. This method, considered here for simple alkali halide dissociation, promises many applications to more complex reactions and to conformational changes. Alignment on the time scale of the experiments is also discussed.

Journal Article↗
PubMed1991

Comparison of the adhesion properties of Deleya marina and the exopolysaccharide-defective mutant strain DMR.

Deleya marina 219 (ATCC 25374) produces large quantities of an acidic exopolysaccharide and characteristically forms mucoid colonies and large aggregates of cells. The exopolysaccharide of wild-type D. marina cells appears to occur as both film and fibrils in electron micrographs. The organization of exopolymeric material was indicative of structural heterogeneity. A spontaneous rough-colony mutant defective in exopolysaccharide, D. marina DMR, has been isolated. The absence of exopolymer corresponds to a nonmucoid, nonaggregating, adhesion-altered phenotype. In microplate adhesion assays, wild-type cells grown at 19 or 25 degrees C attached to hydrophilic surfaces but not to a hydrophobic surface. In contrast, mutant cells exhibited a significantly reduced level of attachment to hydrophilic surfaces and increased adhesion to a hydrophobic surface.

Bacteria↗
PubMed1980

Malignant fibrous histiocytoma of the spermatic cord.

We present 3 cases of malignant fibrous histiocytoma arising from the spermatic cord. This tumor occurs rarely in genitourinary organs and only 2 cases involving the spermatic cord have been reported previously. Recurrence rates of approximately 44 per cent of malignant fibrous histiocytoma in other sites are not improved by radiation or chemotherapy as adjuvants or primary means of treatment. Radical inguinal orchiectomy along with wide en bloc local resection is the therapy of choice.

Aged↗