Biomedical subjects

Y Ron

Publications and source records attributed to Y Ron.

At least 19 recordsLinked to original sources

PubMed2005

Levels of muscle enzymes in the serum after esophageal pneumatic dilation in patients with achalasia.

The success rate of pneumatic dilation of the esophagus in patients with achalasia is variable. We aim to assess whether levels of muscle enzymes in the serum are useful for predicting the efficacy of this procedure. Consecutive adults with symptomatic achalasia treated with pneumatic dilation were included. Blood samples were taken immediately before the procedure and after 12, 24 and 32 h. Clinical efficacy of the pneumatic dilation was evaluated on the basis of a symptom score defined prior to, and 2 months after the procedure. Eleven patients underwent 13 pneumatic dilations. In nine patients this was the first dilation attempt. Ten dilations were clinically effective. The study was discontinued after enzyme levels did not show a trend of increase in any of our patients. Moreover, a statistically significant unexpected decrease in creatine phosphokinase values was found 12 h after the procedure, among the 10 successful dilations. We believe that levels of muscle enzymes in the serum cannot predict the efficacy of pneumatic dilation in patients with achalasia.

Adult↗

PubMed2001

An inducible packaging cell system for safe, efficient lentiviral vector production in the absence of HIV-1 accessory proteins.

Lentiviral vectors based on human immunodeficiency virus type 1 (HIV-1) possess the ability to deliver exogenous genes to both dividing and nondividing cells and to subsequently establish a stable provirus in these target cells, which can allow long-term expression of the transferred gene. Herein we describe a stable packaging cell line that is devoid of HIV-1 tat, vif, vpr, vpu, and nef. In order to avoid any risk of cytotoxicity associated with constitutive expression of HIV-1 protease or the VSV-G envelope protein, transcription of the packaging and envelope constructs was tightly controlled by employing the ecdysone-inducible system. Using this cell line, we have been able to consistently generate concentrated pseudotyped vector virus stocks with titers in the range of 10(8) IU/ml, which can efficiently transduce actively dividing and growth-arrested cells in vitro. This novel packaging cell line for lentiviral vectors facilitates the production of high-titer virus stocks in the absence of replication-competent virus and provides us with an important tool for use in future gene transfer studies.

Cell Line↗

PubMed2001

A gene therapy approach for treating T-cell-mediated autoimmune diseases.

Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease of the central nervous system (CNS) that serves as a model for multiple sclerosis (MS) in humans. In mice, EAE is mediated by Th1 type CD4(+) T cells specific for various myelin proteins which migrate from the periphery to the CNS. Removal or blocking of CD4(+) cells before or shortly after disease induction was shown to prevent disease onset and/or disease progression but also results in general immune suppression. Most treatment regimens for autoimmune diseases currently rely on general suppression of the T-cell compartment most commonly by steroids. In this paper, an experimental, gene therapy-based model is presented in which susceptible mice are made resistant to EAE induction by specifically down-regulating an autoreactive T-cell population. By using a retroviral gene transfer protocol, normal B cells were genetically modified to constitutively express the SJL-specific proteolipid (PLP) encephalitogenic determinant and then adoptively transferred into syngeneic hosts. To ensure appropriate presentation of the exogenous encephalitogenic peptide in association with MHC class II, the encephalitogenic sequence was fused to a lysosomal targeting sequence. Adoptive transfer of syngeneic B cells expressing the PLP encephalitogenic determinant into normal, naive, genetically susceptible mice induced PLP-specific unresponsiveness and completely protected the majority (62% and 83% using an intermediate and a high titer retroviral vector, respectively) of the animals from EAE induction. The remaining animals had a delayed disease onset and/or lower disease severity. All protected mice expressed the exogenous gene in the spleen as detected by reverse transcriptase-polymerase chain reaction.

Adoptive Transfer↗

PubMed2001

Botulinum toxin type-A in therapy of patients with anismus.

INTRODUCTION: Anismus is a common cause of constipation and outlet obstruction. Standard therapy with laxatives or biofeedback has conflicting results. Surgical treatment gives poor results and has practically been abandoned. PURPOSE: This study was designed to evaluate the efficacy of botulinum toxin type-A (Botox) injection to the puborectalis muscle in patients with anismus. METHODS: Twenty-five patients (15 females; mean age, 23.2) with history of constipation and symptoms of outlet obstruction underwent anorectal perfusion manometry and video-proctography. All patients were found to have a nonrelaxing puborectalis muscle on both modalities. All have been unable to expel a rectal balloon. Each patient who participated in the study was randomly assigned to undergo local injection of Botox--10 units to each side of the puborectalis or 20 units to the posterior aspect of this muscle. Eight patients underwent further injections1-5 every 3 months in accordance with previous results. Follow-up was conducted 1, 4, 12, and 24 weeks after injection. Straining, anorectal pain, and overall satisfaction were assessed on a visual analog scale. Weekly evacuation, fecal incontinence, and complications were recorded. At the weekly meeting, each patient underwent anorectal manometry with a balloon expulsion test. RESULTS: Manometric relaxation was achieved after the first injection in 18 patients (75 percent). Once relaxation was achieved, it lasted throughout the follow-up. Nine patients (37.5 percent) expelled the rectal balloon after the first injection. Seven of 16 patients who failed the first injection had an additional one. In 2 patients it was successful (28.6 percent). Symptom improvement of 29.2 percent in straining index was recorded during follow-up. In 3 patients (12.5 percent) pain developed after injection. No other complications were observed. Overall satisfaction with Botox injection results was observed in 58.3 percent. CONCLUSIONS: Botox injection to the puborectalis muscle has been found to have a limited therapeutic effect on patients suffering from anismus. Our results justify the need for further double-blind placebo-controlled trials to determine the exact role of botulinum toxin type-A in anismus.

Adult↗

PubMed2001

Effects of current cigarette smoking on clinical course of Crohn's disease and ulcerative colitis.

Cigarette smoking worsens Crohn's disease (CD) but ameliorates ulcerative colitis (UC). In Israel, where there is no epidemiological association of smoking with CD, we examined the effects of current smoking on the course of CD and UC. Patients at nine public hospitals completed a questionnaire detailing their smoking history, disease course and treatments; subjects altering their smoking habit after the onset of disease were excluded. Sixty-four smokers and 144 nonsmokers had CD, and 34 smokers and 158 nonsmokers had UC. No differences were found between CD smokers and nonsmokers for hospitalizations, operations, and requirement for corticosteroid and immunosuppressive treatment. By contrast, UC smokers had less extensive disease than nonsmokers (P < 0.02) and fewer hospitalizations (P = 0.01) and operations (P = 0.025). Our results agree with a minority of studies showing no adverse effect of smoking on the course of CD, and confirm the protective effect of smoking in UC.

Adolescent↗

PubMed2001

Role of B cells as antigen-presenting cells in vivo revisited: antigen-specific B cells are essential for T cell expansion in lymph nodes and for systemic T cell responses to low antigen concentrations.

Studies in B cell-deficient mice generated by continuous injection of anti-mu antibodies (muSM) showed that T cell priming in lymph nodes was dependent on antigen presentation by B cells. This concept has recently become controversial since a wide range, from complete deficiency to near normal T cell responses, was reported in studies carried out with B cell-deficient mice generated by gene disruption (muMT). In this study we show that in the absence of B cells, T cell responses are greatly reduced in all the available muMT mouse strains although responses in muMT of the C57BL/6 background (which were used for most studies with muMT) were much more variable and could reach up to 42% of control. In contrast, T cell responses in muMT --> F(1) bone marrow chimeras which have the same phenotype as muMT were totally impaired, suggesting a principle difference between mice developing without B cells (muMT mice) and muSM which are made B cell deficient only after birth. Normal T cell priming was completely restored by reconstitution of muMT and muMT --> F(1) mice with syngeneic B cells. Interestingly, only B cell populations containing antigen-specific B cells were capable of reconstituting T cell responses. Monoclonal B cells taken from Ig transgenic mice could not reconstitute responses to an irrelevant antigen. We also found that B cells were also required for systemic T cell priming when antigen concentrations were limiting but were not required for priming (for T cell help) when mice were immunized with a high antigen dose.

Adoptive Transfer↗

PubMed2001

Appendectomy is more frequent but not a risk factor in Crohn's disease while being protective in ulcerative colitis: a comparison of surgical procedures in inflammatory bowel disease.

OBJECTIVE: Appendectomy was shown to be protective in patients with ulcerative colitis (UC). There are fewer data in Crohn's disease (CD). Other operations were less studied. The aim of this study was to investigate the prevalence of appendectomy, cholecystectomy, and tonsillectomy, including their timing, in patients with inflammatory bowel disease in comparison to controls. METHODS: Two hundred seventy-one patients with UC and 260 with CD, 475 clinic controls, and 428 community controls were interviewed. RESULTS: Appendectomy was found in 5.5% patients with UC, in 11% of clinic controls (p < 0.05), and 7.7% of community controls (p = not significant). The differences were more significant for appendectomy before onset of disease. Appendectomy was performed in 19.2% of patients with CD, in 10.9% of clinic controls, and in 10.1% of community controls (p < 0.01). However, there were no significant differences when only appendectomy before onset of disease was considered. Cholecystectomy was found in 1.5% of patients with UC, in 6.1% of clinic controls (p < 0.01), and in 4.5% of community controls (p = not significant). The difference remained significant when confined to operations performed before disease onset. No such difference was found in patients with CD. No significant difference was found in the prevalence of tonsillectomy between patients and controls. CONCLUSIONS: Appendectomy is protective in UC; it is more frequent, but not a risk factor in CD. The role of cholecystectomy should be investigated further.

Adult↗

PubMed2001

Intrachromosomal recombination within the vsp locus of Mycoplasma bovis generates a chimeric variable surface lipoprotein antigen.

A family of 13 related but divergent vsp genes was recently found in the chromosome of the bovine pathogen Mycoplasma bovis. The vsp genomic locus was shown to undergo high-frequency rearrangements and to mediate phenotypic switching of variable lipoprotein antigens (Vsps) on the mycoplasma cell surface. Here we report that the vsp gene repertoire is subject to changes. Genetic analysis of M. bovis clonal isolates displaying distinct Vsp phenotypes showed that an intergenic recombination event between two closely related members of the vsp gene family, the formerly expressed vspA gene and the vspO gene, led to the formation of a new chimeric and functional vsp gene, vspC. The 5' end of the recombination event was identified within the highly conserved vsp-upstream region, while the 3' end was localized within the first repetitive domain (R(A)1) present in both vspA and vspO structural genes. As a result, the vspC gene is an embodiment of the following domains: an N-terminus-encoding region linked to the highly conserved vsp-upstream region provided by the vspO gene; and a C-terminus-encoding region and the more distal and divergent vsp-upstream region acquired from the vspA gene. The generation of chimeric genes encoding surface antigens may provide an important element of genetic variation and an additional source of antigenic diversification within the mycoplasma population.

Amino Acid Sequence↗

PubMed2001

Juxtaposition of an active promoter to vsp genes via site-specific DNA inversions generates antigenic variation in Mycoplasma bovis.

Mycoplasma bovis, the most important etiological agent of bovine mycoplasmosis, undergoes extensive antigenic variation of major and highly immunogenic surface lipoprotein antigens (Vsps). A family of 13 related but divergent vsp genes, which occur as single chromosomal copies, was recently found in the chromosome of M. bovis. In the present study, the molecular mechanism mediating the high-frequency phase variation of two Vsps (VspA and VspC) as representatives of the Vsp family was investigated. Analysis of clonal isolates exhibiting phase transitions of VspA or of VspC (i.e., ON-->OFF-->ON) has shown that DNA inversions occur during Vsp phase variation. The upstream region of each vsp gene contains two sequence cassettes. The first (cassette no. 1), a 71-bp region upstream of the ATG initiation codon, exhibits 98% homology among all vsp genes, while the second (cassette no. 2), upstream of cassette no. 1, ranges in size from 50 to 180 bp and is more divergent. Examination of the ends of the inverted fragments during VspA or VspC phase variation revealed that in both cases, a change in the organization of vsp upstream cassettes involving three vsp genes had occurred. Primer extension and Northern blot analysis have shown that a specific cassette no. 2, designated A(2), is an active promoter and that juxtaposition of this regulatory element to a silent vsp gene by DNA inversions allows transcription initiation of the recipient gene. Further genetic analysis revealed that phase variation of VspA or of VspC involves two site-specific DNA inversions occurring between inverted copies of a specific 35-bp sequence present within the conserved cassette no. 1. A model for the control of Vsp phase variation is proposed.

Antigenic Variation↗

PubMed2001

Transduction of cellular sequence by a human immunodeficiency virus type 1-derived vector.

During studies examining the rate of human immunodeficiency virus type 1 (HIV-1) mutation in a single cycle of replication, the 5' long terminal repeat of one progeny provirus was found to contain an insertion of 147 bp including an entire tRNA sequence as well as an additional 66 bp insertion of nonviral origin. Database searches revealed that 65 of 66 bp aligned with the human CpG island sequence found on chromosomes 6, 14, and 17. Therefore it seems probable that it is of human cellular sequence origin and was transduced by HIV-1. This is the first demonstration that HIV-1 can capture a cellular sequence. The site of integration of the parental provirus was mapped to chromosome 1p32.1. Sequence with homology to the transduced CpG island was not found on chromosome 1, suggesting that the transduced cellular sequence was not linked to the site of viral integration.

Base Sequence↗

PubMed2000

Passive smoking in patients with inflammatory bowel disease: an Israeli multicentre case-control study.

BACKGROUND: The association between smoking and inflammatory bowel disease (IBD) is well established. There are, however, no large scale studies of passive smoking in inflammatory bowel disease and this has never been surveyed in the Jewish population of Israel. AIM: To study the passive smoking exposure of Jewish IBD patients in Israel in a large scale multicentre study. METHODS: Patients with established IBD, aged 18-70 years, were interviewed regarding smoking and other habits. Two controls, one clinic and one neighbourhood, matched by age, sex, community group, and education, were sought for each subject. RESULTS: Five hundred and thirty-four patients (273 ulcerative colitis (UC) and 261 Crohn's disease (CD)), 478 clinic controls and 430 community controls were interviewed. There were no significant differences in the passive smoking habits between IBD patients and their controls. Fifty-one percent of UC patients, 50% of the clinic controls and 58% of the community controls were exposed to passive smoking at home (NS); similar results were found among CD patients (50%, 55% and 56%, respectively). When a quantitative exposure index was used UC patients were significantly less exposed to passive smoking than were their community controls (7.46 +/- 8.40 vs 9.36 +/- 9.46, n = 229, P< 0.031). There was no difference in the exposure to passive smoking among CD patients and their controls. No differences in exposure to passive smoking were found when UC patients who had never smoked were compared with their controls. When the quantitative index was used 'never-smoked' CD patients tended to be less exposed to passive smoking at home than their community controls (5.40 +/- 7.60 vs 8.04 +/- 8.72, P < 0.05). CONCLUSION: There is a lack of association between passive smoking and IBD in Jewish patients in Israel. When a quantitative exposure index was used UC patients were found to be less exposed to passive smoking than their community controls.

Adolescent↗

PubMed2000

Lack of association between smoking and Crohn's disease but the usual association with ulcerative colitis in Jewish patients in Israel: a multicenter study.

OBJECTIVE: The association between smoking and inflammatory bowel disease (IBD) is well established, but data in Jewish patients in Israel were discrepant. The aim of this study was to examine the smoking habits of Jewish IBD patients in Israel in a large scale, multicenter study. METHODS: Patients with established IBD aged 18-70 yr were interviewed in relation to smoking and other habits. Two controls (one clinic and one neighborhood control matched by age, sex, community group, and education) were sought for each subject. RESULTS: A total of 534 patients (273 ulcerative colitis [UC], and 261 Crohn's disease [CD]), along with 478 clinic controls and 430 neighborhood controls, were interviewed. There was no significant difference in the smoking habits between CD patients and their controls. Of patients with CD, 24.5% were current smokers, as compared to 19.9% of clinic controls and 25.2% of neighborhood controls (NS). The odds ratio for CD in current smokers was 1.30 (95% confidence interval 0.85-1.99) versus clinic controls, and 0.96 (0.63-1.46) versus neighborhood controls. There were also no significant differences in the proportion of ex-smokers between the groups. Only 12.9% of UC patients were current smokers versus 21.9. % Clinic controls, and 26.4% community controls (p<0.005). The proportions of ex-smokers were higher in UC patients 29.7% versus 25.9%, and 19.5% in their respective controls (p<0.001 vs. community controls). No significant differences were found in the proportions of never-smokers between IBD patients and controls. All the above trends were similar in four different parts of the country. The proportion of current smokers in UC decreased with the extent of disease (19.7% in proctitis, 13.6% in left-sided, and 4.5% in total colitis) (p<0.05). Patients with UC were more likely to be light smokers(1-10 cigarettes/day), whereas patients with CD were more likely to be moderate smokers (11-20 cigarettes/day) in comparison to their controls. CONCLUSIONS: The lack of association between smoking and CD has now been established in Jewish patients in Israel. The association was found in UC. The stronger genetic tendency in CD may contribute to this discrepancy.

Adolescent↗

PubMed2000

High rate of recombination throughout the human immunodeficiency virus type 1 genome.

The diploid nature of human immunodeficiency virus type 1 (HIV-1) indicates that recombination serves a central function in virus replication and evolution. Previously, while examining the nature of obligatory primer strand transfers during reverse transcription, a high rate of recombination was observed at the ends of the viral genome within the viral long terminal repeats, prompting the following question: does recombination occur at a high rate throughout the genome? To address this question, two vectors based upon different strains of HIV-1 were utilized. The vectors were comprised predominantly of autologous HIV-1 sequence and were approximately the same size as the parental genome. The proviral progeny of heterodimeric virions were analyzed after a single cycle of replication, and the sequence heterogeneity between the two strains allowed direct examination of recombination crossovers. The results obtained indicate that HIV-1 undergoes approximately two to three recombination events per genome per replication cycle. These results imply that both HIV-1 RNAs are typically utilized during reverse transcription and that recombination is an important aspect of HIV-1 replication.

Cell Line↗

PubMed2000

Analgesic effect of topical sodium diclofenac 0.1% drops during retinal laser photocoagulation.

AIMS: To evaluate the analgesic effect of topical sodium diclofenac 0.1% during retinal laser photocoagulation. METHODS: 87 patients, 45 with proliferative diabetic retinopathy treated with two sessions of panretinal photocoagulation (group A), and 42 patients with non-proliferative diabetic retinopathy who underwent grid treatment of the posterior pole (19 bilaterally) (group B). Sodium diclofenac 0.1% or sodium chloride 0.9% drops were topically applied 30-135 minutes before laser treatment in a masked fashion. Patients who had two sessions were given the alternate drug in the second one. Pain level was evaluated immediately after laser treatment with the visual analogue scale (VAS). The results were statistically analysed. RESULTS: Patients in group A reported pain in 85/90 sessions (94%). The average pain level was 44.2% with sodium diclofenac 0.1% drops and 53.1% with sodium chloride 0.9% drops (p = 0.011 by paired t test). Patients in group B reported pain in only 16/60 sessions (26. 7%), and the pain level ranged from 10% to 60% regardless of the kind of drops used. There was no correlation in either group between level of pain and time interval from application of the drops to laser treatment (30-135 minutes) or average energy level used (100-500 mW). CONCLUSION: Sodium diclofenac 0.1% is useful for pain reduction and should be applied before panretinal photocoagulation.

Analgesics↗

PubMed1999

Rel/NF-kappaB can trigger the Notch signaling pathway by inducing the expression of Jagged1, a ligand for Notch receptors.

Jagged1 belongs to the DSL family of ligands for Notch receptors that control the proliferation and differentiation of various cell lineages. However, little is known about the transcription factors that regulate its expression. Here, we show that Jagged1 is a Rel/NF-kappaB-responsive gene. Both c-Rel and RelA induced jagged1 gene expression, whereas a mutant defective for transactivation did not. Importantly, jagged1 transcripts were also upregulated by endogenous NF-kappaB activation and this effect was inhibited by a dominant mutant of IkappaBalpha, a physiological inhibitor of NF-kappaB. Cell surface expression of Jagged1 in c-Rel-expressing cell monolayers led to a functional interaction with lymphocytes expressing the Notch1/TAN-1 receptor. This correlated with the initiation of signaling downstream of Notch, as evidenced by increased levels of HES-1 transcripts in co-cultivated T cells and of CD23 transcripts in co-cultivated B cells. Consistent with its Rel/NF-kappaB-dependent induction, Jagged1 was found to be highly expressed in splenic B cells where c-Rel is expressed constitutively. These results demonstrate that c-Rel can trigger the Notch signaling pathway in neighboring cells by inducing jagged1 gene expression, and suggest a role for Jagged1 in B-cell activation, differentiation or function. These findings also highlight the potential for an interplay between the Notch and NF-kappaB signaling pathways in the immune system.

B-Lymphocytes↗

PubMed1998

Long-term contribution to the myeloid compartment by lineage-committed stem cells.

The current paradigm concerning the kinetics of hematopoiesis is that only the most primitive pluripotential bone marrow stem cells can support prolonged hematopoiesis whereas more differentiated, lineage-committed stem cells can only contribute to a particular lineage for a limited period of time. In this study, we present evidence that in mice, the spleen contains a long-lived myeloid-committed stem cell population(s) that continuously replenishes the mature myeloid lineage for at least 9 months. After myeloid-specific retroviral-mediated gene transfer, the exogenous gene could be detected in thioglycollate-induced macrophages and granulocytes by Southern blot analysis and by in situ polymerase chain reaction on an individual cell basis. The targeted stem cell population does not repopulate the bone marrow in secondary recipients and did not give rise to cells other than cells of the myeloid lineage. It therefore represents the first nonpluripotential stem cell population capable of replenishing a hemopoietic lineage for a long period of time. The ability to target a myeloid-specific stem cell could facilitate gene therapy of congenital disorders of the myeloid system such as lysosomal storage diseases. It also offers a unique opportunity to assess the immunologic consequences of expressing an exogenous gene of choice exclusively in the myeloid lineage.

Animals↗

PubMed1998

The nature of human immunodeficiency virus type 1 strand transfers.

The diploid nature of human immunodeficiency virus type 1 (HIV-1) suggests that recombination serves a central function in virus replication and evolution. A system was developed to examine HIV-1 strand transfers, including the obligatory DNA primer strand transfers as well as recombinational crossovers during reverse transcription. Sequence heterogeneity between different strains of HIV-1 was exploited for examining primer transfer events. Both intra- and intermolecular primer transfers were observed at similar frequencies during minus-strand DNA synthesis, whereas primer transfers during plus-strand DNA synthesis were primarily intramolecular. Sequence analysis of long terminal repeats from progeny proviruses also revealed a high rate of homologous recombination during minus-strand synthesis, corresponding to an overall rate of approximately three crossovers per HIV-1 genome per cycle of replication. These results imply that both viral genomic RNAs serve as templates during HIV-1 reverse transcription and that primer strand transfers and recombination may contribute substantially to the rapid genetic variation of HIV-1.

Base Sequence↗

PubMed1998

Regulated lentiviral packaging cell line devoid of most viral cis-acting sequences.

Packaging cell lines derived from human immunodeficiency virus-1 (HIV-1) are promising tools for in vivo somatic cell gene therapy protocols due to the ability of lentiviruses to infect nondividing cells. We describe here the generation of a safe, stable HIV-1 packaging cell line capable of expressing all of the HIV-1 structural, enzymatic, and regulatory proteins but lacking majority of the cis-acting sequences. The use of an inducible expression system circumvented the cytotoxic and cytostatic effects associated with the expression of some of the HIV-1 viral proteins. Reverse transcriptase activity was detectable in the supernatant from the stable packaging line 1 day after induction, while vector titers peaked 5 days postinduction. Vector titers of up to 3.5 x 10(4) infectious units/ml (IU/ml) were maintained through 8 months following the establishment of the cell line. Lineage-specific gene delivery can be achieved from this established cell line as viral stocks obtained specifically infect CD4(+) target cells. Moreover, this cell line provides a safe and easy to use system for screening of drugs that inhibit HIV-1 replication.

Gene Expression Regulation, Viral↗