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M J Wilson

Publications and source records attributed to M J Wilson.

At least 55 records · Page 3Linked to original sources
PubMed2000

Method for efficient shape parametrization of fluid membranes and vesicles.

In this paper we describe a method for the parametrization of the shapes adopted by fluid membranes and vesicles. The method is based upon a boundary-value approach to geometry description in which smooth surfaces are produced as the solution to an elliptic partial differential equations. Shape parameters are introduced through the boundary conditions, which control the shape of the vesicle models. In combination with a model for the surface energy and a method for numerical minimization, it is shown how the method can accurately approximate the shapes of both axisymmetric and nonaxisymmetric vesicles over a wide range of control parameters. The particular value of the method lies in its ability to parametrize complicated shapes efficiently, a feature that becomes especially valuable when seeking shapes of minimal energy using direct optimization techniques.

Animals↗
PubMed2000

Macrorestriction fingerprinting of "Streptococcus milleri" group bacteria by pulsed-field gel electrophoresis.

Although isolates of the "Streptococcus milleri" group (SMG) of bacteria are regarded as members of the commensal microflora of the body, they are frequently encountered in purulent infections from a range of body sites. The genetic diversity of 91 epidemiologically unrelated SMG isolates (including 37 commensal strains and 49 disease-associated strains) was analyzed by macrorestriction fingerprinting (MF). The genomes were digested with SmaI and ApaI independently, and fragments were resolved by pulsed-field gel electrophoresis. Similarities between banding profiles were determined, and strains were clustered on this basis into dendrograms. In common with other commensal species that have been examined by MF, considerable genetic diversity was revealed. In addition, the clustering of strains tended to support the current taxonomic position of this heterogeneous group. The present study has shown that MF is a powerful tool for characterization of SMG strains and that its use is likely to be of great value in epidemiological and population genetic studies of this group of bacteria.

DNA Fingerprinting↗
PubMed2000

DAP12 and KAP10 (DAP10)-novel transmembrane adapter proteins of the CD3zeta family.

Transmembrane adapter proteins are molecules that associate with receptors and mediate intracellular signals following interaction of the receptor with its ligand. Many such molecules have been characterized in detail, particularly the small TM adapters of the CD3zeta class at the core of the T cell receptor. Recently, two new genetically linked members of this class of transmembrane adapters have been identified called DAP12 (KARAP) and KAP10 (DAP10), respectively. In this review, we discuss this new class of TM adapters using the wealth of knowledge concerning CD3zeta and FcRgamma to highlight similarities and differences with DAP12 and KAP10. In addition, novel receptor families which interact with these TM adapters have also been identified. The role of these receptors and their inhibitory isoforms are discussed.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Cutting edge: KAP10, a novel transmembrane adapter protein genetically linked to DAP12 but with unique signaling properties.

Transmembrane adapter proteins are a class of molecules that mediate signals from an extracellular receptor to the cytoplasm of the cell. We have cloned a novel transmembrane adapter protein called KAP10, a approximately 10-kDa protein that is encoded within 100 bp of the DAP12 locus on human chromosome 19. KAP10 is predominantly expressed in immune cells, including NK cells, T cells, and monocytes. We show that KAP10, unlike other transmembrane adapter proteins, binds phosphatidylinositol-3 kinase following phosphorylation of a cytoplasmic YINM motif, which results in activation of Akt. In addition, we identify KAP10 as being able to bind the adapter protein Grb2. Based on our data, we suggest that this molecule is involved in stimulation and costimulation in cells of both myeloid and lymphoid origin.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Neonatal estrogen stimulates proliferation of periductal fibroblasts and alters the extracellular matrix composition in the rat prostate.

The purpose of this study was to examine whether changes in extracellular matrix (ECM) molecules are associated with the growth inhibition and differentiation defects of the prostate gland following neonatal exposure to estradiol. Using immunocytochemistry (ICC), laminin and collagen IV were localized to the basement membrane (BM) as well to the basal lamina of the periductal smooth muscle of the control developing prostates. In contrast, fibronectin and collagen III were localized throughout the stromal ECM. Exposure to neonatal estrogen altered the staining profile for specific ECM molecules. In the estrogenized rats, a thick layer of cells negative for laminin and collagen IV was observed adjacent to the BM. Electron microscopy and ICC for alpha-actin, fibronectin, and vimentin identified this multicellular layer of periductal cells as differentiated fibroblasts. Peripheral to these fibroblasts, actin-positive smooth muscle formed a second layer of periductal stromal cells. PCNA labeling showed that estrogen exposure increased the fibroblast proliferation. Because many periductal fibroblasts were positive for estrogen receptor alpha (ER alpha) in estrogenized rats, a direct effect of estradiol on their proliferation is suggested. Gelatinolytic gels revealed that estrogen exposure did not alter the activity of matrix metalloproteinases associated with tissue remodeling during prostate morphogenesis. However, the periductal fibroblast layer in estrogenized prostates was devoid of urokinase- and tissue-plasminogen activator, which may potentially alter the localized proteolysis involved in matrix remodeling. It is proposed that proliferation of a multicellular layer of periductal fibroblasts in estrogenized prostates results in a physical barrier that constrains branching morphogenesis and blocks paracrine communications between smooth muscle and epithelial cells which normally regulate differentiation.

Animals↗
PubMed1999

Deoxyribonucleic acid typing methods for medically important microorganisms.

The ability to type microorganisms to a sub-species level plays an essential role in the diagnosis, treatment and control of human infection. Traditionally, differentiation of microorganisms has involved analysis of phenotypic markers. However, these methods are not universally applicable to all microorganisms, and results may be influenced by environmental factors. Recent developments in DNA analysis, together with the limitations of phenotypic methods, have resulted in an increasing use of procedures based on DNA analysis for the typing of clinically important microorganisms. The aim of this review is to provide an overview of the advantages and disadvantages of the genetic typing techniques currently available.

Bacterial Typing Techniques↗
PubMed1998

Codistribution of procathepsin B and mature cathepsin B forms in human prostate tumors detected by confocal and immunofluorescence microscopy.

Cathepsin B (CB) is involved in invasion and metastasis of a variety of solid organ tumors, including human prostate cancer. The tertiary structures of the proenzyme and mature forms of CB are related closely, as revealed by crystallographic studies. However, the cellular distributions of the CB forms have not been defined in human prostate and its tumors. Our objective was to investigate the distribution and codistribution of CB and procathepsin B (proCB) in human prostate tumors. Human prostate tissue samples that were obtained from 21 prostatectomy and/or cystectomy patients were collected immediately after surgery and processed for this study. We used a rabbit antihuman liver CB immunoglobulin G (IgG) that recognizes both mature CB and proCB and a mouse antipropeptide monoclonal antibody IgG that recognizes only proCB. Fluorescein isothiocyanate (FITC)-conjugated donkey antirabbit IgG and indocarbocyanine (Cy3; rhodamine)-conjugated donkey antimouse IgG were used to differentiate localization of the enzyme forms. Immunofluorescence of FITC and Cy3 was examined in prostate sections by using epifluorescence and confocal laser-scanning microscopy. Because fluorescence is dependent on section thickness, time needed for study and photography, and the antigenic sites of proCB and mature CB localized by antibodies and by fluorescent markers (Cy3 vs. FITC), the cellular distributions and the relative intensity of fluorescence on cryostat sections were assessed qualitatively. Immunofluorescence of Cy3 for localizing proCB and of FITC for localizing mature CB were observed in prostatic epithelial cells and their tumors and in stromal connective tissue cells. By using confocal microscopy, colocalization of the enzyme forms in the same cells was indicated by yellow fluorescence. In stromal cells (such as smooth muscles, fibroblast, and macrophages), the distribution of proCB and relative fluorescence intensity was moderate to predominant in human prostate and its tumors. In neoplastic prostate, the cellular distributions of CB ranged from low to predominant levels. In some neoplastic glands, Cy3 fluorescence for proCB was absent, whereas the mature form of CB localized in cancer cells and in the subjacent extracellular matrix. Confocal microscopy showed a close association of CB with extracellular matrix surrounding neoplastic acini and invasive cells, indicating that the enzyme form was probably involved in degradation of the matrix proteins. The negative control study showed no specific immunofluorescence for proCB or CB in prostate cancer cases. We have shown a differential distribution of proenzyme and mature forms of CB in normal prostate, benign prostatic hyperplasia, and neoplastic prostate. The enzyme forms were assessed by determining the cellular distributions of CB and proCB. Our study indicates that the differential distribution of proCB and CB might provide clues into aggressiveness of prostate cancers within Gleason grades. However, we emphasize that our observation should be evaluated in a larger series of prostate samples before a definitive conclusion can be reached. This is the first report to show codistribution of proenzyme and mature forms of CB by using confocal microscopy.

Animals↗
PubMed1998

Isotypic variation of novel immunoglobulin-like transcript/killer cell inhibitory receptor loci in the leukocyte receptor complex.

The leukocyte receptor complex (LRC) on human chromosome 19q13.4 encompasses at least four families of related genes: immunoglobulin-like transcripts (ILT), killer cell inhibitory receptors (KIR), the leukocyte-associated inhibitory receptors (LAIR) and the Fcalpha receptor (Fc(alpha)R). We determined the genomic organization of a region of DNA spanning the junction of the ILT and KIR gene complexes. Extensive sequence data were collected for ILT3, two novel genes, ILT9 and ILT10, and one novel KIR locus (KIRCI). These loci, along with other reported sequences from the region, encoded a leader sequence split into two exons, upstream of two to four immunoglobulin (Ig) domains, each on a separate exon. Downstream of the Ig domains, however, the organization differs markedly between inhibitory and activating ILT. These data are consistent with a highly conserved gene arrangement for all superfamily members suggesting duplication of primordial sequences. ILT3 and KIRCI were in the same head-to-tail orientation as has been described for other KIR loci which may facilitate addition or loss of genes between different haplotypes.

Base Sequence↗
PubMed1998

Low-level steady-state auditory evoked potentials: effects of rate and sedation on detectability.

Steady-state auditory evoked potentials (SSAEPs) in alert adults are most detectable at stimulus or modulation rates of about 40 Hz. Sedation reduces the detectability of 40-Hz SSAEPs and increases it for higher rate SSAEPs. This study examined whether rates higher than 40 Hz would be preferable for detecting responses to low-intensity tones in sedated adults. Fourteen normal adults listened to 640-Hz tones at modulation rates (and toneburst rates) of 20-160 Hz, in 10-Hz steps, at levels of 38 and 58 dB peak equivalent sound-pressure level (peSPL) (20 and 40 dB normal hearing level (nHL) for amplitude-modulated (AM) tones), both alert and sedated (1-2 g chloral hydrate). Sedation reduced both signal (SSAEP) power and noise power at all rates, but noise power reduction was greater for higher rates. Detectability in the alert condition was always greatest at 40 Hz. Under sedation, a second detectability peak was present at 90 Hz for 58-dB peSPL tones, approximately equal to that seen at 40 Hz. At 38 dB peSPL (sedated), peak detectability moved from 40 to 50 Hz. These results suggest that presentation/modulation rates around 40 Hz may be optimal for SSAEP detectability at low levels in adults, whether alert or sedated.

Adult↗
PubMed1998

Hirschsprung disease, microcephaly, mental retardation, and characteristic facial features: delineation of a new syndrome and identification of a locus at chromosome 2q22-q23.

We have identified six children with a distinctive facial phenotype in association with mental retardation (MR), microcephaly, and short stature, four of whom presented with Hirschsprung (HSCR) disease in the neonatal period. HSCR was diagnosed in a further child at the age of 3 years after investigation for severe chronic constipation and another child, identified as sharing the same facial phenotype, had chronic constipation, but did not have HSCR. One of our patients has an interstitial deletion of chromosome 2, del(2)(q21q23). These children strongly resemble the patient reported by Lurie et al with HSCR and dysmorphic features associated with del(2)(q22q23). All patients have been isolated cases, suggesting a contiguous gene syndrome or a dominant single gene disorder involving a locus for HSCR located at 2q22-q23. Review of published reports suggests that there is significant phenotypic and genetic heterogeneity within the group of patients with HSCR, MR, and microcephaly. In particular, our patients appear to have a separate disorder from Goldberg-Shprintzen syndrome, for which autosomal recessive inheritance has been proposed because of sib recurrence and consanguinity in some families.

Abnormalities, Multiple↗
PubMed1998

Enhanced managed care opportunities of group practices. Attention to four key factors can improve a practice's contracting position.

As managed care penetration increases throughout the nation, group practices should evaluate their business composition and practices to make the most of the managed care arrangements into which they enter. By evaluating their practice in terms of its structure, organizational maturity, information collection capabilities, and financial position, a group practice will be able to make changes that will enhance its market position and improve its negotiating leverage.

Data Collection↗
PubMed1998

Prostate specific origin of dipeptidylpeptidase IV (CD-26) in human seminal plasma.

PURPOSE: A number of peptidases which can metabolize certain bioactive peptides and growth factors have been identified in seminal plasma. Our goal in this study was to determine molecular properties and the tissue source(s) for one of these peptidases, dipeptidylpeptidase IV (DPP IV), in human seminal plasma. MATERIALS AND METHODS: We measured the activities of DPP IV with the dipeptide glycylprolyl-p-nitroanalide and its molecular forms using immunoblotting of seminal plasmas of men who were vasectomized or with different sperm concentrations, and in prostatic and seminal vesicle secretions of men undergoing prostatic surgery. RESULTS: DPP IV in seminal plasma of vasectomized men was a membrane associated dimer comprised of subunits of approximately 110 kDa. Its activity did not differ in seminal plasmas of vasectomized, azoospermic, oligozoospermic and normozoospermic men indicating no correlation with the concentration of sperm originally present in the semen. The DPP IV antigen (CD -26) and enzymic activity were present in prostatic secretion, but absent from that of the seminal vesicles. These data indicate that the prostate gland is the primary source of DPP IV activity in seminal plasma. There was little variation in its activities in repeat seminal plasma samples from the same individual, and there was no change in its activity with age to 50 years. CONCLUSIONS: DPP IV in seminal plasma was derived from the prostate gland and it may be useful as a bioindicator of prostate function and/or disease with age in men.

Dipeptidyl Peptidase 4↗
PubMed1997

Effect of a glycerol-containing hypotonic medium on erythrocyte phospholipid asymmetry and aminophospholipid transport during storage.

Previous studies from our laboratory have shown that under blood bank storage conditions red blood cell (RBC) ATP and lipid content were better maintained in a glycerol-containing hypotonic experimental additive solution (EAS 25) than in the conventional storage medium Adsol. The objective of this study was to determine the mechanism of the protective effect of EAS 25, by measuring transmembrane phospholipid asymmetry and the membrane integrity of stored RBCs. Split units of packed RBCs were stored in either EAS 25 or Adsol. RBCs were analyzed after 0, 42, and 84 days and vesicles shed from stored RBCs were analyzed after 84 days of storage. Phospholipid asymmetry was measured by phospholipase A2 digestion (RBCs) and activation of the prothrombinase complex (RBCs, vesicles). RBC membrane exhibited a significantly greater (P < 0.01) amount of phosphatidylethanolamine externalized after storage in Adsol than in EAS 25 (44.3% +/- 11.7 vs. 25.3% +/- 5.7, respectively). Prothrombin converting activities in RBCs were significantly lower than in shed vesicles (P < 0.001) suggesting the presence of phosphatidylserine in the outer monolayer of vesicle, but not in RBC membranes. The rates of inwardly-directed aminophospholipid transport in RBCs decreased by 50% and glutathione levels decreased by approximately 50% in both media. RBC cholesterol and phospholipid content of stored RBCs remained significantly greater (P < 0.01) in EAS 25 than in Adsol. The results indicate that despite comparable reduction in the rate of aminophospholipid transport and reduced GSH concentrations, RBC phospholipid asymmetry was better maintained during storage in EAS 25 than in Adsol. The data suggest that glycerol in the hypotonic EAS helps preserve RBC lipid organization and membrane integrity during storage.

Adenine↗
PubMed1997

Human prostate tumor angiogenesis in nude mice: metalloprotease and plasminogen activator activities during tumor growth and neovascularization of subcutaneously injected matrigel impregnated with human prostate tumor cells.

BACKGROUND: A critical aspect for growth of solid tumors is the development of a blood supply. Our objective was to establish a model for the study of angiogenesis of human prostate tumors by examining the growth of microvessels into Matrigel containing human prostate tumor cells implanted subcutaneously in nude mice. METHODS: Human prostate tumor cell lines PC-3 and LNCaP were injected in Matrigel under the abdominal skin of nude mice and were harvested at 4, 8, and 14 days post-injection. The growth of tumor cells and blood vessels was examined histologically and by immunohistochemical localization of von Willibrand Factor VIII (vWF). Since plasminogen activators and matrix metalloproteases are associated with angiogenesis, the activities and molecular forms of these proteases were determined in Matrigel control and Matrigel-tumor cell subcutaneous implants. RESULTS: Blood vessel formation in the Matrigel implants containing LNCaP and PC-3 cells was demonstrable at 8 days post-injection. However, the pattern of blood vessel formation by the two tumor cell lines was different; PC-3 tumors showed a more invasive phenotype and smaller diameter blood vessels, whereas LNCaP tumors grew as large cellular spheroids surrounded by large, dilated blood vessels. Many blood vessels of PC-3 tumors expressed vWF by day 14 of growth, whereas most blood vessels in LNCaP tumors were immunohistochemically negative for this antigen. Mouse skin blood vessels in the same PC-3 and LNCaP tumor histological sections were positive for vWF. Matrigel contained both plasminogen activator and metalloprotease activities. The plasminogen activator activity in Matrigel control implants was totally inhibited by 4 days post-injection, indicating the presence of an inhibitor provided by the host mouse. LNCaP tumor cells injected did not have appreciable plasminogen activator activity, nor did LNCaP tumors develop plasminogen activator activity with tumor growth post-injection. PC-3 cells did have plasminogen activator activities, which were partially negated after subcutaneous injection (4 days), but then increased again by 8 days post-injection. This increase in plasminogen activator activity was due to urokinase (about 54 kDa) produced by the tumor and not by the mouse host (mouse urine urokinase about 44 kDa). Matrigel alone demonstrated gelatinase B (about 95 kDa) activity in zymograms, and gained considerable gelatinase A (about 70 and 74 kDa) activity after subcutaneous implantation. No metalloprotease activity from the tumor cells could be distinguished over that contributed by the mouse host cells in the Matrigel. Matrigel also contains caseinolytic activities of approximately 56, 80, 85, and 89 kDa. After subcutaneous injection of Matrigel, the 89 kDa form increases considerably in activity and the others are diminished. This pattern is also observed in LNCaP and PC-3 tumors post-injection, except the PC-3 tumors demonstrate increased 56 kDa activity. CONCLUSION: The subcutaneous growth of LNCaP and PC-3 prostate tumor cells in Matrigel in nude mice can be used to study tumor-induced angiogenesis. However, the organization of LNCaP and PC-3 tumor growth and the pattern of microvessels associated with each tumor are different in this system, implying that each tumor has unique influences on the pattern of microvessel development. The mode of action by which this is brought about is not known, but may be due to specific factors produced/ released by the tumor cells.

Animals↗