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PubMed1994

Universal barrier to lateral spread of specific genes among microorganisms.

A genetic circuit to suppress the lateral spread of cloned genes from recombinant to indigenous microorganisms in the environment has been developed. It is based on the endonucleolytic activity of the bacterial toxin colicin E3, which has a distinct target at the 3' end of the 16S ribosomal RNA; this sequence is conserved in virtually all prokaryotic and many eukaryotic genera. Cleavage at this sequence separates the mRNA binding sites from the remainder of the 16S rRNA, thereby inhibiting protein synthesis. While host bacteria carrying the genes for both colicin production and colicin immunity are perfectly viable, lateral transfer of the E3 gene to non-immune recipients results in killing of such recipients. This genetic circuit decreases operational transfer frequencies of cloned genes linked to the E3 gene among a variety of bacterial genera by four to five orders of magnitude. In combination with transposon cloning vectors, the circuit is predicted to reduce the rate of lateral spread of specific genes to ecologically insignificant levels. This system therefore represents a useful tool both to explore the evolutionary and ecological consequences of experimentally reducing lateral gene spread among microorganisms, and to increase the ecological predictability of novel recombinant microorganisms.

Bacteria↗
PubMed2004

A mycobacterial virulence gene cluster extending RD1 is required for cytolysis, bacterial spreading and ESAT-6 secretion.

Initiation and maintenance of infection by mycobacteria in susceptible hosts are not well understood. A screen of Mycobacterium marinum transposon mutant library led to isolation of eight mutants that failed to cause haemolysis, all of which had transposon insertions in genes homologous to a region between Rv3866 and Rv3881c in Mycobacterium tuberculosis, which encompasses RD1 (Rv3871-Rv3879c), a known virulence gene cluster. The M. marinum mutants showed decreased virulence in vivo and failed to secrete ESAT-6, like M. tuberculosis RD1 mutants. M. marinum mutants in genes homologous to Rv3866-Rv3868 also failed to accumulate intracellular ESAT-6, suggesting a possible role for those genes in synthesis or stability of the protein. These transposon mutants and an ESAT-6/CFP-10 deletion mutant all showed reduced cytolysis and cytotoxicity to macrophages and significantly decreased intracellular growth at late stages of the infection only when the cells were infected at low multiplicity of infection, suggesting a defect in spreading. Direct evidence for cell-to-cell spread by wild-type M. marinum was obtained by microscopic detection in macrophage and epithelial monolayers, but the mutants all were defective in this assay. Expression of M. tuberculosis homologues complemented the corresponding M. marinum mutants, emphasizing the functional similarities between M. tuberculosis and M. marinum genes in this region that we designate extRD1 (extended RD1). We suggest that diminished membranolytic activity and defective spreading is a mechanism for the attenuation of the extRD1 mutants. These results extend recent findings on the genomic boundaries and functions of M. tuberculosis RD1 and establish a molecular cellular basis for the role that extRD1 plays in mycobacterial virulence. Disruption of the M. marinum homologue of Rv3881c, not previously implicated in virulence, led to a much more attenuated phenotype in macrophages and in vivo, suggesting that this gene plays additional roles in M. marinum survival in the host.

Animals↗
PubMed1991

Human natural killer cells express different integrins and spread on fibronectin.

Human natural killer (NK) cells adhered and most of them also actively spread on cellular fibronectin (cFn), plasma Fn (pFn) and its Mr 120,000-140,000 or Mr 105,000 cell-binding proteolytic Fn-fragments as well as on heparin-binding Fn-fragments containing the alternative cell binding site. The cells did not spread on vitronectin, laminin or collagens. Adhesion on Mr 105,000 Fn fragment containing the cell binding site, could be prevented by the synthetic peptide GRGDS but not by an inactive peptide, whereas adhesion on heparin-binding Fn fragments was unaffected by the peptide. Spreading of the NK cells led to a distinct reorganization of F-actin. Immunoprecipitation with monoclonal antibodies (MoAb) against the beta 1 integrin subunit of radioactively surface-labelled cells revealed a broad polypeptide band of Mr 140,000 under reducing conditions and a polypeptide doublet of Mr 160,000 and Mr 110,000 under non-reducing conditions. Identical polypeptides, corresponding to the alpha- and beta-subunits of the Fn-receptor complex, were bound to the Mr 105,000 chymotryptic Fn-fragment coupled to Sepharose. Similar experiments with small lymphocytes did not reveal any polypeptides. Immunofluorescence results with McAbs suggested that among the alpha-subunits of integrins, the alpha 3, alpha 4, and alpha 5 subunits are expressed in NK cells. The present results suggest that non-activated NK cells, but not small lymphocytes, express beta 1-integrins, and that at least the Fn-receptors alpha 4 beta 1 and alpha 5 beta 1 may function in the adhesion and migration of NK cells.

Cell Adhesion↗
PubMed1989

Spread of spinal anaesthesia using various doses of plain 0.5% bupivacaine injected at the LIV-V interspace.

Spinal anaesthesia with 3 ml, 4 ml or 5 ml of plain 0.5% bupivacaine was performed in three groups of 20 orthopaedic (ASA 1) patients at the LIV-V interspace. Patients aged less than 20 years or more than 60 years and those outside the normal range of body mass index were excluded. The spread of analgesia was greater in the 4-ml and 5-ml groups compared to the 3-ml group at each testing time (P less than 0.05). The mean maximum cephalad spread of pinprick analgesia (+/- s.d.) 60 min after injection was significantly higher (P less than 0.05) in the 4-ml group (T10 +/- 3.2) and in the 5-ml group (T10 +/- 2.7) than in the 3-ml group (T12 +/- 2.1). The interindividual variability of the cephalad spread of analgesia was greater in the 4-ml and 5-ml groups compared to the 3-ml group (P less than 0.05). The degree of motor block was higher in the 5-ml group than in the 3- and 4-ml groups at 5 and 15 min after injection. In seven patients the first sign of motor block was the patient's inability to flex the ankle, rather than inability to raise an extended leg as was the case in the other patients. In all patients satisfactory anaesthesia for surgery of the lower extremity was achieved.

Adult↗
PubMed2005

Virus spread pattern within infected chicken farms using regression model: the 2003-2004 HPAI epidemic in the Republic of Korea.

During the 2003-2004 epidemic in Korea, the infection time and within-farm spread pattern of virus were analysed for the highly pathogenic avian influenza (HPAI) outbreak on chicken farms using regression models based on epidemiological data. Mortality observed on a given day had a positive linear association with time after initial infection. HPAI spread more rapidly on farms managed by employees and on farms with larger numbers of chicken houses in use. The disease spread more rapidly among layer chickens than among broilers. Using statistical model, we found that farmers recognize the abnormally high mortality resulting from HPAI approximately 5 days after infection. Without any intervention, entire flocks would die within 12 days of introduction of the HPAI virus to the infected farm.

Animal Husbandry↗
PubMed1998

Non-specificity of messenger RNA of alpha-fetoprotein in peripheral blood in detecting early spread of hepatocellular carcinoma in black Africans.

Awareness of early spread of hepatocellular carcinoma is crucial in selecting patients for surgical intervention. Alpha-fetoprotein is widely used as a serum marker for hepatocellular carcinoma. Our aim was to evaluate the specificity of alpha-fetoprotein-mRNA transcription in cells in the peripheral blood for diagnosing early spread of hepatocellular carcinoma in black Africans. Alpha-fetoprotein-, albumin- and prothrombin-mRNA were detected in peripheral blood mononuclear cells by reverse transcription-polymerase chain reaction. Alpha-fetoprotein-mRNA was shown in peripheral blood mononuclear cells in 53% (35/66) of patients with hepatocellular carcinoma, but also in 45% (10/22) of healthy blacks, 64% (14/22) of black patients with acute hepatitis, 55% (11/20) of those with chronic hepatitis or cirrhosis and 75% (9/12) of those with hepatic metastases (from a number of primary sites). Specificity of albumin- and prothrombin-mRNA was better than that of alpha-fetoprotein-mRNA, although the sensitivity was reduced. The corresponding prevalence of albumin-mRNA for each group of patients or controls was 30% (20/66), 9% (2/22), 41% (9/22), 10% (2/20), and 17% (2/12), respectively, and for prothrombin-mRNA 27% (18/66), 4.5% (1/22), 27% (6/22), 20% (4/20) and 17% (2/12), respectively. We conclude that the non-specificity of alpha-fetoprotein-mRNA transcription in peripheral blood in recognizing malignant hepatocytes in the circulation severely limits its usefulness in diagnosing the early spread of hepatocellular carcinoma in black Africans.

Adolescent↗
PubMed1991

Extracorporeal spread and its prognostic impact in stages I and II (FIGO) endometrial carcinoma.

Prognostic risk factors were statistically analyzed from the histopathologic data obtained from 90 Japanese women with stages I and II endometrial carcinoma treated surgically, including systemic retroperitoneal lymph node dissection, between June 1979 and June 1989. In stage Ia endometrial carcinoma, pelvic and paraaortic nodes metastasis were seen in 13.8(4/29)% and 0.0(0/19)% of patients, respectively. In stage Ib, the incidence of pelvic and paraaortic node metastasis was 25.6(11/43)% and 9.7(3/31)%, respectively. In stage II, the incidence was 38.9(7/18)% and 13.3(2/15)%, respectively. Prognosis of patients even with deep myometrial invasion (greater than or equal to 2/3) or G3 tumor was fairly good (5-year survival rate: 87.5% and 85.7%, respectively) if the disease was histologically confined to the uterine corpus. Once the tumor spread outside the corpus uteri, the survival rate of patients was strongly affected by the grade of the tumor, moderate to marked lymph-vascular space invasion of tumor cells, or tumor invading middle or outer third of myometrium (P less than 0.05 for each factor). In summary, endometrial cancer frequently metastasize to pelvic and paraaortic lymph nodes even in the early stages, and lymph node metastasis and other extracorporeal spread of disease have a serious impact on patient survival. Prognosis of patients with extracorporeal spread of disease seems to be determined by the high grade of tumor and lymph-vascular space invasion. These results suggest that surgical exploration including paraaortic lymph node dissection to accurately evaluate the extent of the disease is essential to estimate the patient's prognostic risk and to individualize the treatment schedule.

Female↗
PubMed1982

"Small" melanomas: relation of prognostic variables to diameter of primary superficial spreading melanomas.

In a consecutive series of 648 superficial spreading melanomas a significantly better 5-year disease-free survival rate was observed for patients whose primary tumors were 14 mm or less in diameter when compared with those 15 mm or larger in diameter. Other distinguishing features of the group of "smaller" superficial spreading melanomas were that they occurred in younger patients; were of shorter durations; were more common in women; occurred disproportionately on the lower limbs; were less elevated; tended to be round in shape; were thinner (Breslow); penetrated less deeply (Clark levels); showed less histologic regression; and developed fewer metastases. Based on these findings it is recommended that educational programs be undertaken for the medical profession and for the public to promote early diagnosis and prompt treatment of superficial spreading melanomas when they are small in diameter and more often curable. A color atlas of "small" melanomas is presented.

Adult↗
PubMed1990

Embryologic fusion planes and the spread of cutaneous carcinoma: a review and reassessment.

It has long been held that embryologic fusion planes influence the spread of skin cancer. Embryologic fusion planes have been implicated in the depth of invasion, horizontal spread, and recurrence of cutaneous carcinoma. However, these structures have never been studied in detail. A review of the surgical literature reveals considerable confusion regarding the exact nature, location, and tumor interactions of these fusion planes. We review the gross and microscopic development of sites of embryologic fusion. We examine histologic sections through fusion sites in normally developed adult and fetal fresh cadaver specimens. Our studies, supported by our review of developmental anatomy, indicate that fusion planes do not persist as identifiable anatomic structures that would influence tumor spread.

Adolescent↗
PubMed2005

Comparison of osteoblast spreading on microstructured dental implant surfaces and cell behaviour in an explant model of osseointegration. A scanning electron microscopic study.

OBJECTIVES: To compare interactions between rat calvarial osteoblasts and titanium dental implants with different microstructured surfaces. MATERIAL AND METHODS: Seven commercially available implants were used. Surfaces included plasma-sprayed, grit-blasted and/or acid-etched, smooth-machined and anodised titanium. Two methods were used to compare cell behaviour: (1) A cell-spreading assay in which percentages of cells at four different stages of attachment were identified by scanning electron microscopy and quantified within a 30 min attachment period. (2) Implants were placed in 'pocket culture' within nylon mesh sacs in contact with explanted calvarial bone fragments for 2 and 4 weeks. RESULTS: Surfaces combining grit blasting and acid etching, of microporous topography, showed significantly enhanced rates of cell spreading in comparison with the others. Differential cell morphology was observed in both suspension assays and pocket cultures. In the latter, cells migrated onto all surfaces. Multicellular layers with extracellular matrix (ECM) were present between the layers and on the material surfaces after 2 weeks. After 4 weeks, cell layers were more consolidated, and microstructures were obscured by layers of cells and ECM. Mineralised tissue was seen in association with ECM on grit-blasted surfaces of rough and smooth microtopography. CONCLUSIONS: The two methods provided complementary information: a rough surface of porous microstructure may enhance the rate of cell spreading. Differentiation and calcification occurred on surfaces of both rough and smooth microstructure.

Animals↗
PubMed1998

Determinant spreading during experimental autoimmune encephalomyelitis: is it potentiating, protecting or participating in the disease?

During many autoimmune conditions, a T-cell response initially focused to a self-antigen evolves towards the recruitment of T cells to multiple antigenic determinants. Here we discuss whether such determinant spreading involves T cells activated in the peripheral lymphoid organs, or alternatively, whether the diversification occurs after infiltration of the initiating T cells into the target organ, for example, into the central nervous system during experimental autoimmune encephalomyelitis, a prototype for multiple sclerosis. The expression of myelin antigens in the thymus and spleen may not only contribute to the induction of tolerance but also to determinant spreading. In this case, the outcome of in vivo diversification may ultimately be determined by the balance between type 1 and type 2 responses to antigenic determinants derived from myelin components. Thus, spreading T cells could modulate disease progression positively or negatively, depending upon the nature of the accompanying cytokine secretion profile.

Animals↗
PubMed1998

Reciprocal T-B determinant spreading develops spontaneously in murine lupus: implications for pathogenesis.

Recent work from several laboratories has shown that, in contrast to the widely held notion that one autoimmune disease is caused by one or a few related autoantigenic determinants, autoimmunity is fundamentally a continuously evolving process. The autoimmune responses shift, drift and diversify with time not only to other determinants in the original antigen but also to other antigens. We have described a form of determinant spreading--reciprocal T-B determinant spreading--where the induction of first T cells by peptides from an autoantibody molecule could lead to help provided to a variety of B cells displaying a cross-reactive version of the original determinant. The response spreads in this way by reciprocal T-B stimulation until large cohorts of T and B cells have expanded. Such spontaneous expansion must be important in clinical disease, since tolerance induction to a limited set of T-cell determinant peptides derived from an anti-DNA antibody VH region delayed the appearance of IgG anti-dsDNA antibodies and onset of lupus nephritis in the NZB/NZW F1 mouse model of systemic lupus erythematosus. Understanding the diversification patterns in autoimmune responses has enormous implications in developing peptide-targeted therapies.

Animals↗
PubMed1999

Lectins inhibit periodontal ligament fibroblast attachment, spreading and migration on laminin substrates.

The ways in which carbohydrate signals from the extracellular matrix influence the responses of periodontal ligament (PDL) fibroblasts are essentially unknown. The purpose of this study, using video digital image analysis, was to examine the effects of lectins on the attachment, spreading and migrational responses of rat periodontal ligament fibroblasts on the highly glycosylated glycoprotein laminin (LN) in vitro. PDL fibroblasts were isolated from rat molar teeth and grown in culture. Bound LN and control substrates (bovine serum albumin and untreated plastic) were incubated with solutions of either wheatgerm agglutinin (WGA), specific for N-acetylglucosamine, or concanavalin A (ConA), specific for mannose, in 96-well plates. Unbound lectin was rinsed away and 10.0 x 10(3) cells were seeded per well and allowed to attach for 1.5 h. Incubation of LN substrates with WGA, prior to the addition of any cells, inhibited PDL fibroblast binding more than 5-fold. ConA, however, had no effect on cell binding but inhibited mean individual cell spreading nearly 3-fold under similar assay conditions. The effects could be prevented by adding each lectin's respective specific sugar. The lectins had no effects on the control substrates. In a 24-h cell migration assay WGA and ConA both significantly inhibited migration of PDL fibroblasts. It is likely that WGA inhibited cell attachment and cell migration, by binding to oligosaccharides and blocking access to adjacent polypeptide cell recognition sequences on LN. The results from the ConA experiments, where binding was allowed but spreading was severely inhibited, suggest a possible informational role for the carbohydrates present on LN.

Acetylglucosamine↗
PubMed1975

Twitching motility and possession of polar fimbriae in spreading Streptococcus sanguis isolates from the human throat.

A collection of 19 strains of alpha haemolytic streptococci, isolated from throat swabs and characterized by production of spreading zones around colonies on blood agar, was found to constitute a very homogeneous group with morphological, physiological and biochemical characters corresponding to those of streptococci of ser-group H, or Streptococcus sanguis, and they all appeared to possess the group H antigen. They all had a common agglutinogen and, in addition, heterogeneous agglutinogens. The spreading growth, which appears to be a common property of S. sanguis, was due to twitching motility, and the spreading cultures possessed polar fimbriae. tneither twitching motility nor the possession of polar fimbriae have been observed in gram-positive bacteria before.

Agglutination Tests↗
PubMed1985

Effect of gamma interferon on spreading of mouse peritoneal macrophages on solid surfaces.

The influence of a homologous gamma interferon preparation (MuIFN-gamma) on in vitro spreading of freshly-seeded unelicited mouse peritoneal macrophages (MPM) was tested. Light microscopy and scanning electron microscopy observations gave comparable results. Addition of MuIFN-gamma enhanced the spreading on solid surfaces, especially 3-5 hours after seeding. Maximal effect was achieved with 10 units of IFN. Addition of specific anti-MuIFN-gamma or treatment of the preparation at pH 2 eliminated both antiviral activity and effect on spreading of MPM.

Animals↗
PubMed2000

The increasing significance of international trade in equids and its influence on the spread of infectious diseases.

Expansion in international trade in equids and equine semen has been especially notable over the past 10-15 years among those countries historically identified as having significant breeding and performance horse industries. The continuing trend towards globalization of the horse industry received additional impetus in January, 1995, following establishment of the World Trade Organization (WTO), whose primary goal is to promote freer economic exchange between member countries through the reduction or elimination of protectionist barriers to trade. Continued growth in international trade, closely related to changing trends in the horse industry, has greatly increased the risk of spread of a wide range of equine infectious diseases between countries. In consequence, the global distribution of certain of these diseases is likely to change in the future. Within the past 30-40 years, there have been numerous confirmed instances of the spread of specific diseases through the international movement of equids or shipment of semen, some of which have resulted in epidemics of major economic importance. Under the Sanitary-Phytosanitary Agreement of the WTO, national agencies have had to rethink their traditional "zero-risk" approach in regulating the importation of equids or equine semen from other countries. Mindful of the risks of disease spread inherent in such transactions, authorities must now accept that primary emphasis in today's global economic climate must be on greater facilitation of trade, rather than attempting to provide absolute disease preventive safeguards.

Animal Husbandry↗
PubMed1996

Efficacy of a novel copper-based footbath preparation for the treatment of ovine footrot during the spread period.

OBJECTIVE: To determine the efficacy of a novel copper based footbath preparation (CHF-1020) for treatment of ovine footrot during the spread period. DESIGN: A series of field trials with treated and control groups run together. ANIMALS: Mobs of at least 125 sheep on each of six properties in southern New South Wales with equal numbers of controls. PROCEDURE: Sheep of group A were treated after minimal paring by making them stand in CHF-1020 for 15 minutes. Treatment was undertaken at intervals throughout the period of the trials (14 September to 17 December 1993). Group A sheep were run on the same pasture as those from group B (untreated sheep). RESULTS: The percentage of sheep exhibiting clinical signs of ovine footrot at the start of the trial ranged from 35 to 88% at score 3 or higher, using a 0 to 5 footscoring system. During the trial, the percentage of infected sheep (greater or equal to score 2) in group B increased and ranged from 40 to 90%. The level of infected sheep in group A on each property was reduced progressively to 1 to 16%. Cure rates of 45 to 94% were achieved, with the lowest rate being on a property with a metal footbath. The next lowest cure rate was 73%. Results indicated that treatment should be undertaken at 2-weekly intervals while spread continues. Treated sheep can be returned to contaminated pastures. CONCLUSION: CHF-1020 is effective during the spread period and can be used for the progressive eradication of ovine footrot.

Administration, Topical↗
PubMed1979

The spread of sensitization of polymodal nociceptors in the rabbit from nearby injury and by antidromic nerve stimulation.

1. Ninety-three polymodal nociceptor units with unmyelinated axons were isolated from rabbit sural nerves. Twenty-three were used for control data. These showed normal sensitization on repeated heating of their receptive fields, measured here as a drop in mean heat threshold. 2. Small injuries were made 5 (n = 15) or 10 (n = 12) mm outside the receptive fields of some polymodal nociceptors. This resulted in the development of spontaneous firing and lowered thresholds to heating of the receptive field. 3. Local anaesthetic previously injected into the site of injury blocked this spread of heat sensitization. Previous injection of saline had no effect. 4. Antidromic stimulation of the sural nerve, proximal to the recording site, also resulted in heat sensitization of polymodal nociceptors (n = 10). 5. Possible mechanisms for the spread of sensitization of polymodal nociceptors from nearby injury are discussed. Analogies are drawn between these results and those of Lewis (1935--36) on the spread of cutaneous ;yperalgesia around a skin injury in man.

Action Potentials↗