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Biomedical subjects

L Wolff

Publications and source records attributed to L Wolff.

At least 55 records · Page 3Linked to original sources
PubMed1994

Bacteria as risk markers for periodontitis.

Specific microbial species have been closely associated with periodontitis. Through longitudinal studies, some of these microbial species have been implicated in the etiology of progressive periodontal disease. Although putative periodontal pathogens are often isolated from individuals with severe periodontitis, they also frequently inhibit the subgingival environment and are not always associated with advanced disease. In this respect, it is becoming increasingly apparent that there is no single etiology of the various periodontal diseases. Destructive periodontal diseases are the result of environmental, host, and bacterial factors. Microorganisms, however, are essential components of any model for progressive periodontitis. This paper selectively reviews bacteria as risk markers for periodontitis. Attention focuses on bacteria in conjunction with behavioral patterns (oral hygiene habits and smoking) and host response (gingival crevicular fluid substances) as risk markers for periodontitis. Prospective studies implicating specific bacteria in progressive periodontitis are addressed and a bacterial risk assessment model for progressive periodontitis is discussed with respect to the interplay between bacterial, environmental, and host markers.

Bacteria↗
PubMed1993

Activation of c-myb is an early bone-marrow event in a murine model for acute promonocytic leukemia.

Insertional mutagenesis of c-myb by Moloney murine leukemia virus occurs in 100% of promonocytic leukemias (MMLS) induced by the virus. These leukemias, which resemble acute monocytic leukemia-M5 in humans are induced only in mice undergoing a peritoneal chronic inflammatory response. We have found that two leukemia-specific gag-myb mRNAs in MML provide molecular markers for detection of preleukemic cells in hematopoietic tissue in vivo. The two aberrant RNAs result from splicing of gag to either exon 3 or 4 of c-myb, depending on the site of proviral integration. After reverse transcription-PCR with nested primers and hybridization with specific gag-myb junction probes, one cell, having aberrant c-myb message, could be detected in a minimum of 10(5) liver cells or 10(6) spleen or bone-marrow cells. This approach was used to examine hematopoietic tissues of mice after pristane injection to induce inflammation and virus inoculation. Cells with gag-myb mRNAs could be detected as early as 2 weeks after virus inoculation. In mice receiving both pristane and virus, there was evidence of preleukemic cells in 83% of the mice by 3 weeks after virus infection. Furthermore, 100% of the mice were positive for preleukemic cells by 8 weeks, even though only 50% of mice have been shown to succumb to MML (peak time for disease latency is 12-16 weeks). Cells with these aberrant c-myb messages were initially detected in the bone marrow, but during intermediate stages of disease development these cells disseminated to the spleen, liver, and granuloma. At preleukemic times, from 3 to 8 weeks after virus infection, a lower percentage of mice were positive in the group that did not receive pristane compared with mice in the group receiving pristane. However, at 18 weeks, 100% of the mice in the group receiving virus only had evidence of cells expressing gag-myb RNA in their spleens and/or bone marrow; it is of interest that mice inoculated with virus alone never develop MML. This approach for detecting preleukemic cells will now allow the study of mechanisms by which these preleukemic cells progress to a more transformed state and, perhaps, to a more differentiated state.

3T3 Cells↗
PubMed1993

The development of Pneumocystis carinii pneumonia in germ-free rats requires immunosuppression and exposure to the Pneumocystis carinii organism.

Adult germ-free rats treated with dexamethasone and exposed to a non-sterile environment did not harbor or develop Pneumocystis carinii cysts or trophozoites after 10 weeks of immunosuppression. Only when they were exposed to infected, conventional rats and treated with dexamethasone for 8 weeks or longer, did adult germ-free rats develop P. carinii infection.

Animals↗
PubMed1992

Involvement of the spleen in preleukemic development of a murine retrovirus-induced promonocytic leukemia.

An acute myeloid leukemia can result from the inoculation of Moloney murine leukemia virus into BALB/c mice undergoing a 2,6,10,14-tetramethylpentadecane-induced chronic inflammatory response in the peritoneal cavity. This leukemia is ultimately observed in the peritoneal cavity as an ascites with cells infiltrating the granulomatous tissue. It has been proposed, however, that hematopoietic organs such as the spleen and bone marrow are involved in preleukemic development of Moloney murine leukemia. Therefore, to determine if the spleen plays a role in this development, mice were splenectomized at various times relative to virus inoculation. When splenectomies were performed 3 days before and 2, 4, 6, and 8 weeks after virus inoculation there was, in all cases, a decreased death rate compared to sham-splenectomized controls. The greatest difference in death rate due to promonocytic leukemia was observed when mice were splenectomized at 4 weeks after virus inoculation. The decrease in disease incidence observed as a result of splenectomy was not caused by decreased virus spread in hematopoietic organs or an alteration in the profile of the cellular infiltrate in the granuloma. It was found, however, that the spleens of 2,6,10,14-tetramethylpentadecane-treated mice, relative to those of normal mice, have a significantly increased number of granulocyte-macrophage colony-forming cells and a slightly increased number of multipotential colony-forming cells. These observations suggest that a population of target cells for transformation, consisting of granulocyte-macrophage precursor cells, may reside in the spleen. Alternatively, partially transformed cells may reside temporarily in the spleen during the developmental stages of the disease process.

3T3 Cells↗
PubMed1992

Infrequent p53 mutation in mouse tumors with deregulated myc.

An invariant genetic lesion in mouse plasmacytomas is deregulated expression of c-myc as a consequence of chromosomal translocation. However, retroviral and transgenic studies suggest that additional genetic lesions may contribute to the genesis of plasmacytomas. The p53 tumor suppressor gene is a likely contributor to this genetic lesion, since there is a high incidence of p53 mutation in Burkitt's lymphomas and B-ALL (L3), both of which contain translocations involving c-myc analogous to those in plasmacytomas. In addition, p53 has been shown to be a transcriptional modulator of c-myc expression. In a survey of 27 mouse plasmacytomas by single-strand conformation polymorphism, we identified a single mutation (3.7% incidence), suggesting that p53 lesions are not frequent contributors to plasmacytomagenesis. A similar study of macrophage-monocyte tumors generated by a c-myc-containing retrovirus also indicates a lack of p53 involvement in deregulated c-myc expression. These results suggest that the specific maturation stage of transformed B-lymphocytes, independent of c-myc deregulation, may be the critical factor which determines the involvement of mutant p53.

Amino Acid Sequence↗
PubMed1992

New sites of proviral integration associated with murine promonocytic leukemias and evidence for alternate modes of c-myb activation.

Murine promonocytic leukemias involving insertional mutagenesis of the c-myb locus can be induced by replication-competent retroviruses. In previously studied promonocytic leukemic cells induced by Moloney murine leukemia virus (called MML), the provirus has been invariably integrated upstream of exons 3 or 4 and the leukemic cells expressed aberrant RNAs with fused virus-myb sequences. Furthermore, Myb expressed by these cells has been shown to be truncated by 47 or 71 amino acids. The present report examines the mechanisms of myb activation in leukemias induced by two other retroviruses, amphotropic virus 4070A and Friend strain FB29 (the leukemias are called AMPH-ML and FB-ML, respectively). This study revealed two additional c-myb proviral insertion sites in these promonocytic leukemias. One FB-ML had a proviral integration in exon 9, and expressed a C-terminally truncated Myb protein of 47 kDa similar to that previously demonstrated to be expressed in the myelomonocytic cell lines NFS60 and VFL-2. However, a sequence of reverse-transcribed and amplified RNA from this leukemia demonstrated that the truncation involved a loss of 248 amino acids compared with a loss of 240 amino acids in the myelomonocytic cell lines. Another leukemia had a provirus integrated in the 5' end of c-myb upstream of exon 2 (in the first intron) and produced a Myb protein that was indistinguishable on sodium dodecyl sulfate-polyacrylamide gel electrophoresis from normal Myb. This latter leukemia (FB-ML R1-4-10) expressed Myb with the smallest N-terminal truncation observed so far in promonocytic leukemias; translation begins at an ATG within c-myb exon 2, leading to loss of only 20 amino acids from the N terminus. Unlike the proteins produced in Moloney murine leukemia virus-induced promonocytic leukemias (MML) that have larger truncations, this protein has an intact DNA binding region and does not contain N-terminal amino acids encoded by gag. However, this protein is similar to all N-terminally truncated Mybs so far studied, in that the truncation resulted in deletion of a casein kinase II phosphorylation site which has been proposed to be involved in regulation of DNA binding.

Amino Acid Sequence↗
PubMed1992

Minocycline slow-release formulation effect on subgingival bacteria.

The purpose of this study was to determine the microbiological efficacy of an adjunctive minocycline periodontal formulation delivered subgingivally. Subjects were systemically healthy but exhibited severe periodontitis; i.e., probing depths greater than 6 mm. The two study groups included individuals who received minocycline or a placebo periodontal formulation after root planing. Subgingival plaque samples were obtained at baseline; prior to treatment; and at 1, 3, and 6 months. Plaque was evaluated by darkfield microscopy and further analyzed for total dark-pigmented Bacteroides species, P. intermedia, P. gingivalis and Streptococcus, Actinomyces, Eikenella, Actinobacillus, Capnocytophaga, and Fusobacterium species using cultivable flora techniques. In addition, plaque was evaluated for yeast on a selective agar medium. When compared to the placebo, the minocycline group had significantly lower proportions of spirochetes at 1 and 3 months and lower proportions of motile rods at 3 months. Furthermore, when compared to the placebo group, the minocycline patients had lower mean proportions of dark-pigmented Bacteroides spp. and P. intermedia at 1 and 3 months as well as lower proportions of E. corrodens at 1 month. The minocycline group had significant decreases in proportions of spirochetes at 1 and 3 months, motile rods at 1 and 3 months, and increases in cocci at 1, 3, and 6 months when compared to baseline. In the placebo group, root planing was also effective at decreasing spirochetes at 1, 3, and 6 months, but with significant differences seen only at 3 and 6 months. However, the degree of reduction in spirochete proportions was greater in the minocycline group when compared with the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces↗
PubMed1991

Repair of mycotic aneurysm of the innominate artery with homograft tissue.

The case of a 46-year-old drug addict who underwent repair of a mycotic aneurysm of the innominate artery with a 12-mm homograft is presented. The homograft was obtained from the descending thoracic position in a young child. Replacement of infected arteries with various artificial grafts risks recurrent infection and anastomotic disruption. The use of a homograft conduit in this case was successful in restoring the appropriate blood flow without infection. We suggest that the homograft conduit can be used in other areas with similar results.

Aneurysm, Infected↗
PubMed1991

Acute myeloid leukemia induction by amphotropic murine retrovirus (4070A): clonal integrations involve c-myb in some but not all leukemias.

Amphotropic murine retrovirus 4070A was demonstrated to be highly leukemogenic when inoculated intravenously into adult DBA/2 mice that were undergoing an intense chronic inflammatory response, but was nonleukemogenic in the absence of inflammation. The virus-induced promoonocytic leukemias, designated AMPH-ML, are similar morphologically and in cell surface marker expression to monocytic leukemias, called MML and MF-ML, previously shown to be induced by Moloney murine leukemia virus and MF-3 virus (a recombinant between Friend murine leukemia virus and Moloney murine leukemia virus) and resemble certain mature acute monocytic leukemias in humans (AML subtype M5). Approximately two-thirds of the AMPH-MLs (subgroup I) were demonstrated to have alterations in the 5' end of the c-myb locus, an event which occurs in 100% of MML and MF-ML. Data indicate that proviral insertions in AMPH-ML subgroup I resulted in aberrant c-myb mRNA expression and truncation of its translation product at the amino terminus. Approximately one-third of the AMPH-MLs (subgroup II) had not undergone any DNA rearrangements at the c-myb locus. In addition, their transcripts and protein products were of normal size. These latter leukemias also had not undergone DNA rearrangements in c-myc, although retroviruses expressing myc have previously been shown to induce monocyte-macrophage tumors in mice undergoing a chronic inflammation. That subgroup II leukemias had at least one clonal viral insertion suggests that there may be other sites in the cellular genome that can be activated by insertional mutagenesis in these murine acute monocytic leukemias.

Animals↗
PubMed1990

Regions of the Moloney murine leukemia virus genome specifically related to induction of promonocytic tumors.

Moloney murine leukemia virus (MuLV) can be a potent inducer of promonocytic leukemias in mice that are undergoing a chronic inflammatory response. The neoplasms are, at least in part, associated with insertional mutagenesis of the c-myb locus. Evidence is presented for the existence of at least two genetic elements of the virus that are crucial to induction of this disease but are not required for viral replication in hematopoietic tissues or induction of lymphoid disease. These genetic elements were detected by testing the pathogenicity of recombinants between Moloney and Friend MuLVs, the latter of which is nonleukemic to myeloid cells under these conditions, and by testing Moloney MuLV-based viruses that have nonretroviral sequences inserted at specific endonuclease sites in their long terminal repeats (LTRs). Analysis of the Moloney/Friend recombinants showed that there are sequences within the structural gene domain of Moloney, but not Friend, MuLV that are necessary for promonocytic leukemia, whereas the LTRs of the MuLVs are equally effective for promonocytic tumor formation and insertional mutagenesis of the c-myb gene. Experiments with viruses which were mutagenized in the LTR by insertions demonstrated that there is a specific genetic element in the U3 region of the LTR of Moloney MuLV, upstream of the 75-base-pair enhancer which, when interrupted, results in loss of leukemogenicity for cells in the monocytic lineage but not cells in the lymphoid lineage. We conclude, therefore, that promonocytic leukemia induction, in Moloney MuLV-infected mice undergoing a chronic inflammatory response, requires specific sequences in the structural gene region of Moloney MuLV as well as other sequences in the regulatory region of the virus.

Animals↗
PubMed1990

[Social dependence of early retirement statistics].

In the current discussion of health care policy, the trend in early retirement figures is frequently taken as an indicator of the efficiency of the health care services in our country, or of the disease promoting factors at the workplace. The present study shows that no such direct monitoring of these two problem complexes by reference to the early retirement figures is possible. On the contrary, the high degree of dependence of these figures on social factors is demonstrated. The development of early retirement figures substantially depends on supreme court legislation, job market situation and exceptional demographic alterations. These and others reservations make the invalidity figures basically unsuitable for tracing developments in health care policy.

Aged↗
PubMed1989

Transmembrane domain of the envelope gene of a polycythemia-inducing retrovirus determines erythropoietin-independent growth.

Both the polycythemia-inducing and the anemia-inducing strains of Friend spleen focus-forming virus can induce acute erythroleukemia in susceptible adult mice. However, only cells infected with the polycythemia-inducing strain become erythropoietin-independent for proliferation and differentiation. The sequences responsible for the altered erythropoietin responsiveness have previously been localized to a 678-base-pair EcoRI-Cla I fragment at the 3' end of the envelope gene. This region is now further analyzed by dividing it into two fragments by using the Fok I restriction site. Two recombinants were made by replacing either the 558-base-pair EcoRI-Fok I or the 113-base-pair Fok I-Cla I env gene fragments from the anemia-inducing strain of spleen focus-forming virus with sequences derived from the polycythemia-inducing strain. Our results indicate that the 113-base-pair Fok I-Cla I fragment, which encodes primarily the transmembrane domain of the envelope protein, determines erythropoietin-independent growth.

Amino Acid Sequence↗
PubMed1988

A chronic inflammatory response. Its role in supporting the development of c-myb and c-myc related promonocytic and monocytic tumors in BALB/c mice.

This study demonstrates that an inflammatory response caused by the injection of pristane into the peritoneal cavity of mice provides a useful system for rapid induction of myeloid tumors by retroviruses. Two such tumors, which developed in the peritoneal cavity with average latencies of 68 to 71 d and incidences of greater than 50%, are 1) the McML, mature monocyte-macrophage tumors induced by retroviral constructs containing exons 2 and 3 of c-myc cDNA, and 2) the MML, promonocytic tumors induced by Moloney murine leukemia virus infection and its integration into the c-myb locus. Development of both neoplasms is clearly dependent on the intense i.p. inflammatory response, inasmuch as mice given the viruses and not pristane fail to develop these tumors. Although both types of tumors appear in the peritoneal cavity, the MML tumors that arise by i.v. injection of Moloney murine leukemia virus may actually originate via infection, and perhaps transformation, of precursor hemopoietic cells outside the peritoneal cavity, followed by migration of the cells to the peritoneal cavity. This is suggested by the fact that i.v.v but not i.p. injection of virus is an efficient method of producing these particular myeloid tumors. Although both McML and MML tumors require the inflammatory environment for their development, treatment of mice with a nonsteroid anti-inflammatory drug, indomethacin, has no effect on McML monocyte/macrophage tumors but completely prevents the development of the MML promonocyte tumors.

Animals↗
PubMed1988

Inherited C3 deficiency with recurrent infections and glomerulonephritis.

A 10-year-old Laotian boy had homozygous deficiency of the third component of complement and recurrent bacterial infections beginning at age 5 months. Cellular and humoral immunity were normal, as were polymorphonuclear leukocyte chemotaxis and bactericidal activities. Serum complement-mediated hemolytic, chemotactic, and opsonic activities were deficient. In vitro addition of purified C3 to patient serum restored hemolytic complement to normal levels, and plasma infusion during each of four episodes of pneumonia significantly enhanced serum opsonic activity for as long as 36 hours. A renal biopsy specimen revealed mesangiopathic glomerulonephritis, although significant levels of circulating IgG immune complexes were not detected. These findings further support the association of C3 deficiency with immune-complex disease and suggest that plasma infusion may be an adjunct to antibiotic therapy in the management of severe pyogenic infections in patients with C3 deficiency.

Bacterial Infections↗
PubMed1988

The spleen focus-forming virus (SFFV) envelope gene, when introduced into mice in the absence of other SFFV genes, induces acute erythroleukemia.

Previous studies in our laboratory and others have been consistent with the hypothesis that the envelope (env) gene of the spleen focus-forming virus (SFFV) is the only gene essential for the induction of acute erythroleukemia. However, no studies have been carried out with the SFFV env gene in the complete absence of other SFFV sequences. To accomplish this goal, we isolated the sequences that encode the envelope glycoprotein, gp52, of SFFVA and expressed them in a Moloney murine leukemia virus-based double-expression vector containing the neomycin resistance gene. The method used to produce retrovirus stocks in tissue culture cells affected the expression of the gp52 gene in the vector and the subsequent pathogenicity of the vector in mice. Highly pathogenic virus stocks were obtained by cotransfection of vector and helper virus DNAs into fibroblasts, followed by virus replication and spread through the cell population. Mice infected with this stock developed a rapid erythroid disease that was indistinguishable from that induced by the entire SFFV genome, and the virus stock transformed erythroid cells in vitro. Spleen cells from the diseased mice expressed the SFFV env gene product but not the SFFV gag gene product. As expected, mice given the virus containing the SFFV env gene in the reverse orientation did not express the SFFV env gene product or develop erythroleukemia. This study, therefore, demonstrated (i) that double-expression retroviral vectors can be used under specific conditions to produce viruses expressing high levels of a particular gene and (ii) that incorporation of the SFFV env gene into such a vector in the absence of other SFFV sequences results in a retrovirus which is as pathogenic as the original SFFV.

Animals↗
PubMed1987

Amplified RNase H activity in Escherichia coli B/r increases sensitivity to ultraviolet radiation.

Strains of E. coli B/r transformed with the plasmid pSK760 were found to be sensitized to inactivation by ultraviolet radiation (UV) and to have elevated levels of RNase H activity. Strains transformed with the carrier vector pBR322 or the plasmid pSK762C derived from pSK760 but with an inactivated rnh gene were not sensitized. UV-inactivation data for strains having known defects in DNA repair and transformed with pSK760 suggested an interference by RNase H of postreplication repair: uvrA cells were strongly sensitized, wild-type and uvrA recF cells were moderately sensitized and recA cells were not sensitized; and minimal medium recovery was no longer apparent in sensitized uvrA cells. Biochemical studies showed that post-UV DNA synthesis was sensitized and that the smaller amounts of DNA synthesized after irradiation, while of normal reduced size as indicated by sedimentation position in alkaline sucrose gradients, did not shift to a larger size (more rapidly sedimenting) upon additional incubation. We suggest an excess level of RNase H interferes with reinitiation of DNA synthesis on damaged templates to disturb the normal pattern of daughter strand gaps and thereby to inhibit postreplication repair.

DNA Damage↗
PubMed1987

Moloney murine leukemia virus-induced myeloid tumors in adult BALB/c mice: requirement of c-myb activation but lack of v-abl involvement.

BALB/c mice treated with pristane and Abelson virus have been used as an animal model system for the rapid induction of plasmacytomas. Myelomonocytic tumors with helper Moloney murine leukemia virus clonally inserted into the c-myb locus were observed in about 10% of pristane-primed BALB/c mice infected with Abelson virus. However, v-abl was absent in almost all of those tumors. Since Moloney virus is thought to induce mostly T-cell lymphomas, we have carried out studies to investigate this alteration of disease specificity and to determine whether v-abl played an obligatory role in the development of these tumors. We found that, whereas lymphomas developed late (greater than 3 months) in both pristane-primed and unprinted control mice, the myelomonocytic tumors arose at a high frequency, within 3 months, but only in pristane-treated mice. Clonal Moloney virus insertion was again found in each of the seven myelomonocytic tumors examined. Northern blot analyses and S1 mapping studies revealed the presence of virally promoted chimeric mRNAs that lack the three 5'-most myb coding exons. Hence it appears that the requirement for the v-abl gene product in tumor induction is not obligatory. Our results also indicate that tumor-specific alteration at the 5' end of the myb gene plays an important role in the development of these tumors.

Abelson murine leukemia virus↗