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Biomedical subjects

P Williams

Publications and source records attributed to P Williams.

At least 325 records · Page 18Linked to original sources
PubMed1992

Fine-needle aspiration biopsy for the measurement of hepatic iron concentration.

The potential application of fine-needle aspiration liver biopsy in the documentation of hepatic iron overload has been assessed in iron-loaded rats. Fine-needle aspiration and standard liver biopsy specimens were obtained from three groups of animals supplemented with oral and parenteral iron for 2 to 6 mo. The mean dry weights of standard and fine-needle biopsy specimens were 7.41 +/- 0.77 (+/- S.E.M.) and 0.57 +/- 0.54 mg, respectively. Hepatic iron in fine-needle aspiration biopsy specimens correlated significantly with hepatic iron in standard liver biopsy specimens as measured by biochemical determination, computerized image analysis and histological grading (r greater than 0.9, p less than 0.001). In conclusion, we have shown that fine-needle aspiration biopsy of the liver can obtain sufficient tissue for biochemical measurement of the hepatic iron concentration in an animal model of iron overload. The clinical applications of fine-needle aspiration liver biopsy in human beings with iron overload is currently being investigated.

Analysis of Variance↗
PubMed1992

Mass spectrometry of DNA mixtures by laser ablation from frozen aqueous solution.

We report time-of-flight mass spectra of test mixtures of six single-stranded DNA segments. The segments range in size from 8 to 60 nucleotides (molecular weight range 2413 to 18,602 Da). The best mass spectra were obtained by pulsed laser ablation of thin frozen films of an aqueous solution of the mixture from an oxidized copper substrate. These mass spectra are dominated by the molecular-ion peak for each DNA segment, and show little evidence of fragmentation, peak broadening or cluster formation. In contrast, mass spectra obtained using UV laser ablation from an anthranilic acid matrix yield broad peaks with evidence of fragmentation, and DNA segments longer than 26 nucleotides are difficult to detect.

Base Sequence↗
PubMed1992

Acute rejection of lung allografts with various immunosuppressive protocols.

Between February 1990 and December 1991, 69 patients who survived for a minimum of 5 days after single-lung (27), double-lung (32), or heart-lung transplantation (10) were studied to learn the incidence and severity of acute rejection and the possible effects of various immunosuppressive protocols on this rejection. Acute rejection was less common (2.1 versus 3.1 episodes/patient) after transplantation in those 30 candidates who received rabbit antithymocyte globulin for the first 5 postoperative days versus the 28 who were maintained on cyclosporine, azathioprine, and prednisone alone (p < 0.05), but no patient escaped at least one episode. Patients given cyclosporine received more 3-day courses of methylprednisolone (p < 0.02) than those given rabbit antithymocyte globulin (2.5 versus 1.7 courses). Although no disadvantage in terms of infectious morbidity was noted in the rabbit antithymocyte globulin group, no obvious intermediate advantage was noted in survival (85% at 12 months) or grade of rejection or airway flows. The most common histopathologic grades were mild (A2) and moderate (A3); the average grade was A2.3. FK 506 was tested in 11 patients, and early results are promising relative to low early and likely fewer late episodes of rejection. No differences were noted in the likelihood of rejection for any procedures.

Acute Disease↗
PubMed1992

Human serum albumin as a probe for surface conditioning (opsonization) of block copolymer-coated microspheres.

The adsorption of human serum albumin to polystyrene microspheres sterically stabilized with block copolymers, was investigated using photon correlation spectroscopy and laser doppler anenometry. The block copolymers used were non-ionic surfactants of the poloxamer and poloxamine series made of polyoxyethylene and polyoxypropylene chains. Photon correlation spectroscopy and laser doppler anenometry showed that the coating reduced the adsorption of the protein to the polystyrene microspheres surface. Quantitative studies using 125I-labelled human serum albumin and sodium dodecyl sulphate-polyacrylamide gels (in combination with densitometry), were employed to evaluate the adsorption of human serum albumin to uncoated and coated polystyrene microspheres. They confirmed that the hydrophilic polyoxyethylene steric layer, created by coating with the block copolymers, reduced the adsorption of human serum albumin. Moreover, the amount of human serum albumin adsorbed was related to the polyoxyethylene content of the block copolymers.

Absorption↗
PubMed1992

Modulation of surface antigen expression by Klebsiella pneumoniae in response to growth environment.

Growth in pooled human body fluids [urine, serum and peritoneal dialysate (HPD)] modulated the expression of cell envelope antigens in virulent (serotype O1:K1) and avirulent (serotype O1:K66) Klebsiella pneumoniae strains. Marked variations in the outer membrane protein (OMP) and lipopolysaccharide (LPS) profiles were noted when broth-grown cells were compared with those of bacteria cultured in body fluids. In particular, for the O1:K1 serotype strain, growth in the latter resulted in: (a) the expression of at least five iron-regulated OMPs in the 74-87 kDa range, the pattern of which was medium dependent; (b) alterations in the migration of the LPS core polysaccharide; and (c) the reversion of isogenic O-:K+ and O-:K- mutants to the O+ phenotype after growth in fresh serum but not in heat-inactivated serum, urine or HPD. Similar results were obtained for the O1:K66 serotype, although no variation in the migration of the LPS core was noted. For both O1:K1 and O1:K66 serotypes, neither the surface exposure of O1 serotype LPS nor the production of K-antigen (capsular polysaccharide) was affected by growth in body fluids. No reversion of K- mutants to the K+ phenotype was observed. These data illustrate the phenotype flexibility of this opportunistic pathogen and emphasise the crucial role of the O- rather than the K-antigen in protecting K. pneumoniae from complement-mediated serum killing.

Antigens, Bacterial↗
PubMed1992

Relationship of AIDS-related attitudes to sexual behavior changes in adolescents.

The impact of the acquired immunodeficiency syndrome (AIDS) epidemic on a group of adolescents was investigated by surveying 197 sexually active, predominantly African-American, urban high school students. Reported sexual behavior changes were evaluated in relation to AIDS-related knowledge and attitudes. Over 50% of the students decreased their frequency of sexual activity, increased their condom use, and/or decreased their number of partners. These students had significantly higher scores on a measure of worry about vulnerability to human immunodeficiency virus (HIV) infection than those whose behavior had not changed. AIDS knowledge, AIDS beliefs, and AIDS-related anxiety interacted with gender to affect sexual behavior change. Male students reporting decreased frequency of sexual activity, for example, had more accurate beliefs about AIDS than males reporting no decrease. Among female students, however, those reporting decreased frequency had less accurate beliefs than those reporting no decrease. These results highlight the importance of considering gender and specific sexual behaviors when designing AIDS education interventions.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Direct gene transfer into nonhuman primate myofibers in vivo.

Previously, we showed that rodent muscle has the ability to take up and express plasmid genes injected intramuscularly. This study now demonstrates that nonhuman primate muscle also has this ability to express injected plasmids. A scaled-up version of the standard large preparation of plasmid DNA allowed several tens of milligrams of CCC plasmid DNA to be relatively easily produced and administered to monkeys. After the injection of the E. coli beta-galactosidase reporter gene in pRSVLac-Z, foreign gene expression was localized to both type I and type II myofibers. The luciferase reporter gene in pRSVL was used to quantify the amount of expression. The multiple implantation of plasmid DNA pellets was more efficient in expressing luciferase than the injection of DNA in normal saline. Luciferase activity persisted for at least 4 months after injection. However, the luciferase expression was considerably less than that in rodents. Preliminary studies explored why expression was less in monkeys. Of particular interest was the increased thickness of the perimysium of monkeys as compared to that in rodents. This increased connective tissue may decrease delivery of the plasmid DNA to the myofibers. Anti-nuclear or anti-DNA antibodies were not observed, even after repetitive DNA administrations, and no adverse effects were observed in any of the monkeys.

Adenosine Triphosphatases↗
PubMed1992

Long-term persistence of plasmid DNA and foreign gene expression in mouse muscle.

Plasmid pRSVL persisted and expressed luciferase for at least 19 months in mouse skeletal muscle after intramuscular injection. Other injected plasmids also stably expressed long-term suggesting that any plasmid DNA could stably persist and express in muscle. Plasmid DNA was demonstrated by quantitative PCR in some of the muscle DNA samples for at least 19 months after injection. The methylation pattern of the plasmid DNA remained in its bacterial form indicating that the foreign DNA did not replicate in the muscle cells. The electroporation of total cellular DNA from injected muscles into bacteria indicated that the plasmid DNA was extrachromosomal. Chromosomal integration of plasmid DNA was searched for by electroporating the injected muscle DNA into bacteria after restriction enzyme digestion and ligation. No plasmids containing plasmid/chromosome junctions were observed in over 1800 colonies examined. Lack of integration increases the theoretical safety of this gene transfer technique. Long-term stability of plasmid DNA in muscle indicates that muscle is an attractive target tissue for the introduction of extrachromosomal plasmid or viral DNA for the purpose of gene therapy.

Animals↗
PubMed1992

Tn916 insertion mutagenesis in Escherichia coli and Haemophilus influenzae type b following conjugative transfer.

Transposon Tn916 was shown to be capable of direct conjugative transfer in broth and membrane matings between strains of Escherichia coli K12 and between E. coli K12 and Haemophilus influenzae type b. Only Tn916 was transferred, but Tn916 donor ability was not itself inheritable by the recipients and seemed to be associated with the presence of Tn916 on a non-conjugative pBR322-derived vector in the original donor strain. Transfer of Tn916 by conjugation was found to be an efficient method for producing insertion mutations in the chromosome of recipient cells. Although such insertions were unstable when the cells were grown under non-selective conditions, it was possible to show that over 40% of the isolated Tn916 insertions in the chromosome of E. coli K12 were in gene(s) concerned with histidine biosynthesis, implying that there is a partial hot-spot for Tn916 insertion on the E. coli K12 chromosome. When a strain of H. influenzae type b was used as a recipient, out of approximately 1500 transconjugants tested, two mutants were isolated with insertions in genes controlling the expression of iron-regulated transferrin-binding proteins. These mutants constitutively produced major 76 kDa and minor 90 kDa proteins which bound transferrin, even when grown under iron-sufficient conditions. Tn916 insertion mutagenesis, following transfer by conjugation, is a convenient method for isolating mutations in genes concerned with iron acquisition by this important human pathogen.

Bacteriological Techniques↗
PubMed1992

Common antigenic domains in transferrin-binding protein 2 of Neisseria meningitidis, Neisseria gonorrhoeae, and Haemophilus influenzae type b.

There is now considerable evidence to show that in the Neisseria and Haemophilus species, membrane receptors specific for either transferrin or lactoferrin are involved in the acquisition of iron from these glycoproteins. In Neisseria meningitidis, the transferrin receptor appears to consist of two proteins, one of which (TBP 1) has an M(r) of 95,000 and the other of which (TBP 2) has an M(r) ranging from 68,000 to 85,000, depending on the strain; TBP 2 binds transferrin after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroblotting, but TBP 1 does not do so. The relative contributions of these two proteins to the binding reaction observed with intact cells and to iron uptake are presently unknown. However, they are being considered as potential components of a group B meningococcal vaccine. Analogous higher- and lower-molecular-weight proteins associated with transferrin binding have been found in N. gonorrhoeae and Haemophilus influenzae. Previous work with polyclonal antibodies raised in mice with whole cells of iron-restricted N. meningitidis showed that the meningococcal TBP 2 exhibits considerable antigenic heterogeneity. Here, we report that antiserum against purified TBP 2 from one strain of N. meningitidis cross-reacts on immunoblotting with the TBP 2 of all meningococcal isolates examined, as well as with the TBP 2 of N. gonorrhoeae. This antiserum also cross-reacted with the TBP 2 of several strains of H. influenzae type b, thus showing the presence of common antigenic domains among these functionally equivalent proteins in different pathogens; no cross-reaction was detected with a purified sample of the human transferrin receptor.

Animals↗
PubMed1992

Cell envelope proteins of Staphylococcus epidermidis grown in vivo in a peritoneal chamber implant.

Staphylococcus epidermidis was grown in vivo in chambers implanted intraperitoneally in rats. The cell wall and cytoplasmic membrane protein profiles of the in vivo-grown organisms were compared with those of S. epidermidis grown in vitro in nutrient broth (NB), in iron-restricted NB, or in pooled human peritoneal dialysate (HPD). Compared with growth in broth and in common with growth in HPD, growth in vivo in chambers resulted in the repression of many S. epidermidis wall proteins, with proteins of 27, 42, 54, and 70 kDa predominating. Growth in vivo also resulted in the induction of two iron-repressible cytoplasmic membrane proteins of 32 and 36 kDa, which were also present in staphylococci grown in HPD and in iron-restricted NB. Immunoblotting experiments revealed that in sera taken 21 days after inoculation of the intraperitoneal chambers, the predominant antibody response to cell envelope proteins was directed against the 32- and 36-kDa iron-repressible membrane proteins.

Animals↗
PubMed1992

Evidence for in vivo expression of transferrin-binding proteins in Haemophilus influenzae type b.

Haemophilus influenzae type b acquires transferrin-bound iron via a siderophore-independent mechanism involving direct contact between the human iron-binding glycoprotein and the bacterial cell surface. Evidence has accumulated to show that the transferrin receptor consists of at least two iron-regulated outer membrane transferrin-binding proteins (TBPs), of which one has a molecular mass of around 100 kDa (TBP1) and the other has a molecular mass of 60 to 90 kDa (TBP2). In H. influenzae type b strain Eagan, proteins of 76, 90, and 107 kDa appear to be involved in transferrin binding. To determine whether these TBPs are expressed during growth in vivo, strain Eagan was recovered without subculture from the intraperitoneal cavities of infected infant rats. By using a dot blot assay, outer membranes prepared from these in vivo-grown bacteria, unlike those grown in iron-sufficient broth, bound human transferrin and produced the 76-, 90-, and 107-kDa TBPs. Immunoblotting experiments using convalescent sera from infected rats also revealed the presence of antibodies to the 76- and 90-kDa strain Eagan TBPs. In addition, convalescent sera from three of four patients recovering from H. influenzae type b meningitis contained antibodies to the 90- and 105-kDa TBPs of the corresponding infecting strain. Furthermore, fresh clinical isolates of H. influenzae type b recovered from blood and cerebrospinal fluid showed constitutive expression of the TBPs, which became iron regulated only after prolonged in vitro subculture on iron-sufficient medium. This contrasted with the laboratory-adapted Eagan strain, in which the TBPs remained iron regulated even after animal passage. These findings indicate that the H. influenzae type b transferrin receptor is expressed during experimental animal and human infections.

Animals↗
PubMed1992

Expression of naked plasmids by cultured myotubes and entry of plasmids into T tubules and caveolae of mammalian skeletal muscle.

Plasmid DNA or artificial mRNA injected intramuscularly into skeletal muscle via a 27 g needle expressed transgenes at relatively efficient levels in skeletal myofibers and cardiac cells. In the present study, several approaches were used to determine the mechanism of cellular uptake. After exposure of naked plasmid DNA, primary rat muscle cells in vitro expressed transgenes to a much greater extent than other types of immortalized or primary cells. In vivo light microscope studies showed that intramuscularly injected plasmid DNA was distributed throughout the muscle and was able to diffuse through the extracellular matrix, cross the external lamina, and enter myofibers. Electron microscope studies showed that colloidal gold conjugated to plasmid DNA traversed the external lamina and entered T tubules and caveolae, while gold complexed with polylysine, polyethylene glycol or polyglutamate primarily remained outside of the myofibers. The results indicate that it is highly unlikely that the plasmid DNA enters the myofiber simply by the needle grossly disrupting the sarcolemma. In addition, transient membrane disruptions do not appear to be responsible for the uptake of DNA. Furthermore, no evidence for endocytosis could be found. The possible uptake of plasmid DNA by some type of cell membrane transporter, in particular via potocytosis, is discussed.

3T3 Cells↗
PubMed1992

Nabumetone compared with naproxen in the treatment of rheumatoid arthritis: a multicenter, double blind, randomized, parallel group trial in hospital outpatients.

In this double blind, randomized, parallel group study, 298 patients with rheumatoid arthritis received nabumetone (2000 mg/day) or naproxen (1000 mg/day) for 3 months. At the end point, nabumetone treated patients exhibited significant improvement in pain, Ritchie articular index, and duration of morning stiffness when compared to baseline. In contrast, naproxen treated patients showed significant improvement only in Ritchie articular index. Nabumetone was significantly more effective than naproxen for pain relief. More nabumetone treated patients withdrew due to lack of efficacy than naproxen treated patients. However, nabumetone was better tolerated than naproxen because fewer patients withdrew for adverse events or experienced severe adverse events, and significantly fewer patients required treatment for adverse events.

Adult↗