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Biomedical subjects

A Ben-Nun

Publications and source records attributed to A Ben-Nun.

At least 19 recordsLinked to original sources
PubMed2006

Video-assisted thoracoscopic surgery for recurrent spontaneous pneumothorax: the long-term benefit.

BACKGROUND: Management of recurrent primary spontaneous pneumothorax by open surgery was considered the treatment of choice until recently. The major drawbacks of this management are the prolonged postoperative pain and cosmetic results. In the last decade, video-assisted thoracoscopic surgery (VATS) has replaced the routine use of open surgery. Most papers that compared limited open surgery to VATS addressed the early postoperative results, and studies that assessed the long-term results focused primarily on the rate of recurrence and pulmonary function tests. The aim of this study was to compare the outcome of minithoracotomy and VATS with emphasis on patients' long-term, subjective perspective and satisfaction. METHODS: Medical records of patients with recurrent primary spontaneous pneumothorax were retrospectively reviewed. Patients who underwent surgical treatment by limited thoracotomy (63 patients) or VATS (58 patients) more than 3 years ago were enrolled. Hospital medical charts were used to compare the early postoperative results. Outpatient clinic records and a telephone questionnaire were employed to evaluate long-term results. RESULTS: There was no mortality or major morbidity in either group, and hospitalization time was similar. Patients in the thoracotomy group needed significantly higher doses of narcotic analgesia for a longer period. There were two cases of recurrence in the VATS group (3%). Seventy-eight percent of patients in the VATS and 21% in the thoracotomy group classified their pain as insignificant a month following the operation (P < 0.05). Three years following surgery, 97% of the VATS group patients considered themselves completely recovered from the operation compared with only 79% in the thoracotomy group (P < 0.05). Nineteen percent of the thoracotomy group and 3% of the VATS group suffered from chronic or intermittent pain necessitating use of analgesics more than once a month. Thirteen percent of patients from the open procedure group required services from the pain clinic. Patients in the VATS group were, in general, much more satisfied with their operation and with the surgical scars compared with patients from the thoracotomy group. CONCLUSION: We recommend video-assisted surgery as the first-line surgical treatment for patients with recurrent primary spontaneous pneumothorax. This recommendation is based on its somewhat favorable early postoperative course, the superior long-term outcome, and patient satisfaction.

Adolescent↗
PubMed2003

Aberrant T-cell receptor signalling of interferon-gamma- and tumour necrosis factor-alpha-producing cytotoxic CD8+ Vdelta1/Vbeta16 T cells in a patient with chronic neutropenia.

We previously found that the peripheral blood (PB) mononuclear cells (MCs) (PBMCs) of a patient with chronic neutropenia contained an expanded population of cytotoxic CD8+ T cells using a variable (V) region delta1 gene product in the T-cell receptor-alpha (TCR-alpha) polypeptide [Vdelta1-constant(C)alpha+ T cells]. Sequencing of polymerase chain reaction (PCR) amplification products have now revealed a productive Vdelta1/joining (J)alphaIGRJa03/Calpha rearrangement of the TCR-alpha gene, predominantly associated with a Vbeta16/Dbeta2.1/Jbeta2.1/Cbeta2 TCR-beta gene, in these cells. Furthermore, we detected a markedly deficient proliferative response of the patient PBMCs to triggering with monoclonal antibodies (MoAbs) to the CD3 molecule, contrasting with a substantial response to the Vbeta3, 12, 14, 15, 17 and 20-specific staphylococcal enterotoxin B (SEB) superantigen, suggesting defective TCR-mediated activation of the Vdelta1+/Vbeta16+ clone. Moreover, whereas triggering of Vdelta1- T cells cultured with interleukin-2 (IL-2) by MoAb to the CD3 molecule enhanced proliferation, Vdelta1-Calpha+ T cells were inhibited by MoAbs to either CD3 or Vdelta1. Vdelta1-Calpha+ T-cell clones spontaneously secrete interferon-gamma (IFN-gamma) and were further induced to release tumour necrosis factor (TNF-alpha) when triggered by anti-CD3 plus phorbol ester. Aberrant signalling by the clonotypic TCR together with the functional properties of the CD8+ Vdelta1+/Vbeta16+ clone may thus contribute to the immunohaematological abnormalities observed in this patient.

Amino Acid Sequence↗
PubMed2002

gammadelta T cell subsets in patients with arthritis and chronic neutropenia.

BACKGROUND: An abnormal distribution of subsets of gammadelta T cells, which are a component of the inflammatory infiltrate in arthritic synovium, has been demonstrated in the peripheral blood (PB) of patients with arthritis and neutropenia. OBJECTIVE: To evaluate whether the clinical manifestations of patients with arthritis and neutropenia are related to the specific gammadelta T cell subset predominant in the PB. METHODS: Flow cytometry of PB lymphocytes in six consecutive patients with chronic neutropenia and arthritis was performed. Variable (V) gamma and delta gene families were analysed by polymerase chain reaction. cDNA was subjected to direct automated sequencing of T cell receptor (TCR) genes. RESULTS: Three patients had non-deforming and non-erosive rheumatoid factor (RF)(+) polyarticular rheumatoid arthritis, RF(+) oligoarticular arthritis, or RF(-) non-deforming oligoarticular psoriatic arthritis with persistent expansions of Vgamma1(+)/Vdelta2(+), Vgamma2(+)/Vdelta2(+), or Vgamma1(+)/Vdelta (undetermined (2- 1-)) T cells, respectively. The other three patients, without persistent expansion of gammadelta T cells, had either non-deforming and non-erosive oligo- or polyarthritis with a balanced distribution of several Vdelta and Vgamma genes, or severe erosive RF(+) arthritis with deficiency of all but Vgamma1(+)/Vdelta1(+) T cells. CONCLUSIONS: gammadelta T cell lymphoproliferations in chronic neutropenia and arthritis use different Vgamma and Vdelta gene families, often forming T cell receptor (TCR) structures that are infrequent in normal adult PB. Arthritis with Vgamma1(+)/Vdelta2(+), Vgamma2(+)/Vdelta2(+), or Vgamma1(+)/Vdelta2(-)/Vdelta1(-) gammadelta T cells in the PB is non-deforming and non-erosive, suggesting a protective effect of these cells, as opposed to a more pathogenic contribution of Vgamma1(+)/Vdelta1(+) cells.

Aged↗
PubMed2001

Vaccination for neuroprotection in the mouse optic nerve: implications for optic neuropathies.

T-cell autoimmunity to myelin basic protein was recently shown to be neuroprotective in injured rat optic nerves. In the present study, using the mouse optic nerve, we examined whether active immunization rather than passive transfer of T-cells can be beneficial in protecting retinal ganglion cells (RGCs) from post-traumatic death. Before severe crush injury of the optic nerve, SJL/J and C3H.SW mice were actively immunized with encephalitogenic or nonencephalitogenic peptides of proteolipid protein (PLP) or myelin oligodendrocyte glycoprotein (MOG), respectively. At different times after the injury, the numbers of surviving RGCs in both strains immunized with the nonencephalitogenic peptides pPLP 190-209 or pMOG 1-22 were significantly higher than in injured controls treated with the non-self-antigen ovalbumin or with a peptide derived from beta-amyloid, a non-myelin-associated protein. Immunization with the encephalitogenic myelin peptide pPLP 139-151 was beneficial only when the disease it induced, experimental autoimmune encephalomyelitis, was mild. The results of this study show that survival of RGCs after axonal injury can be enhanced by vaccination with an appropriate self-antigen. Furthermore, the use of nonencephalitogenic myelin peptides for immunization apparently allows neuroprotection without incurring the risk of an autoimmune disease. Application of these findings might lead to a promising new approach for treating optic neuropathies such as glaucoma.

Animals↗
PubMed2001

Modified Seldinger technique for the insertion of standard chest tubes.

Closed tube thoracostomy is a standard procedure for the evacuation of air, blood, or other materials from the pleural space. This paper describes a modification of the Seldinger technique that facilitates chest tube insertion. Either a Nelaton or Thieman catheter is threaded into the side drainage hole and out the tip of a standard Argyle-type chest tube. After using the clamp to insert the catheter into the pleural space through a previously dissected tract, the catheter serves as a guide over which the chest tube is inserted. The technique is simple to use, effective, and safe. It employs standard, inexpensive materials to insert chest tubes in such a way as to minimize the potential traumatic complications inherent in other techniques.

Chest Tubes↗
PubMed2001

Reversal of the CD4(+)/CD8(+) T-cell ratio in lymph node cells upon in vitro mitogenic stimulation by highly purified, water-soluble S3-S4 dimer of pertussis toxin.

Pertussis toxin (PT), a holomer consisting of a catalytic S1 subunit and a B oligomer composed of S2-S4 and S3-S4 dimers, held together by the S5 subunit, exerts profound effects on immune cells, including T-cell mitogenicity. While the mitogenic activity of PT was shown to reside fully within the B oligomer, it could not be assigned to any particular B-oligomer component. In this study, we purified the S3-S4 dimer to homogeneity under conditions propitious to maintenance of the native conformation. In contrast to previous reports which suggested that both S3-S4 and S2-S4 dimers are necessary for mitogenic activity, our preparation of the highly purified S3-S4 dimer was as strongly mitogenic as the B oligomer, suggesting that the S3-S4 dimer accounts for the mitogenic activity of the B oligomer. Moreover, in vitro stimulation of naive lymphocytes by the S3-S4 dimer resulted in reversal of the normal CD4(+)/CD8(+) T-cell ratio from approximately 2:1 to 1:2. The reversal of the CD4(+)/CD8(+) T-cell ratio is unlikely to be due to preferential apoptosis-necrosis of CD4(+) T cells, as indicated by fluorescence-activated cell sorter analysis of annexin-stained T-cell subsets, or to preferential stimulation of CD8(+) T cells. The mechanism underlying the reversal requires further investigation. Nevertheless, the data presented indicate that the S3-S4 dimer may have potential use in the context of diseases amenable to immunological modulation.

Animals↗
PubMed2000

Rhesus monkeys are highly susceptible to experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein: characterisation of immunodominant T- and B-cell epitopes.

Eight rhesus monkeys with different MHC backgrounds were immunized with myelin oligodendrocyte glycoprotein (MOG). All developed severe experimental autoimmune encephalomyelitis associated with large inflammatory foci and extensive demyelination. T-cell autoreactivity to MOG was directed against three main epitopes encompassed within amino acids 4-20, 35-50 and 94-116, of which two are also immunodominant epitopes for the autoimmune T cell response to MOG in patients with MS. A strong B cell response to MOG was observed in all monkeys and major epitopes recognized were located within amino acids 4-26, 24-46 and 44-66/54-76.

Animals↗
PubMed2000

Restricted immune responses lead to CNS demyelination and axonal damage.

Although autoreactive T-cells have a pivotal role in initiating the inflammatory process in experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS), recent evidence suggests a relevant role for autoantibodies specific for myelin proteins as well. To examine the role of B-cells in the cerebrospinal fluid of patients with MS, we analyzed the V(H) gene usage in ten MS patients by PCR technologies. Analysis of HCDR3 length revealed an oligoclonal accumulation of B-cells. Sequence analysis of the V(H)3 and V(H)4 gamma transcripts of two MS individuals demonstrated that this accumulation was related to the expansion and somatic diversification of a limited groups of B-cell clones. These findings are indicative of a chronic and intense antigenic stimulation occurring in the CNS. Animal models, such as EAE, are of particular importance in order to elucidate the pathogenetic effector mechanisms in autoimmune demyelination. In a non-human primate model of EAE, we describe that the immunodominant T-cell epitope is presented exclusively by a monomorphic DRB1 allele, suggesting that susceptibility to EAE may be linked to this unique restriction and, therefore, providing a possible mechanism for MHC linkage to diseases. Moreover, we report on the presence of inflammation, sharp demyelination and axonal damage in EAE induced with whole myelin as well as with recombinant myelin oligodendrocyte glycoprotein (MOG), but not with myelin basic protein alone. The presence of axonal pathology was supported by immunohistochemistry with anti-amyloid precursor protein and anti-non phosphorilated neurofilaments monoclonal antibodies within early active demyelinated plaques. These findings suggest that axonal damage may be an early event in the pathogenesis of autoimmune demyelinating diseases of the CNS and highlights the importance of animal models in which therapies targeting repair and axonal survival may be exploited.

Animals↗
PubMed2000

Myelin/oligodendrocyte glycoprotein-induced autoimmune encephalomyelitis in common marmosets: the encephalitogenic T cell epitope pMOG24-36 is presented by a monomorphic MHC class II molecule.

Immunization of common marmosets (Callithrix jacchus) with a single dose of human myelin in CFA, without administration of Bordetella pertussis, induces a form of autoimmune encephalomyelitis (EAE) resembling in its clinical and pathological expression multiple sclerosis in humans. The EAE incidence in our outbred marmoset colony is 100%. This study was undertaken to assess the genetic and immunological basis of the high EAE susceptibility. To this end, we determined the separate contributions of immune reactions to myelin/oligodendrocyte glycoprotein (MOG) and myelin basic protein to the EAE induction. Essentially all pathological features of myelin-induced EAE were also found in animals immunized with MOG in CFA, whereas in animals immunized with myelin basic protein in CFA clinical and pathological signs of EAE were lacking. The epitope recognition by anti-MOG Abs and T cells were assessed. Evidence is provided that the initiation of EAE is based on T and B cell activation by the encephalitogenic phMOG14-36 peptide in the context of monomorphic Caja-DRB*W1201 molecules.

Animals↗
PubMed2000

T-cells specific for soluble recombinant oligodendrocyte-specific protein induce severe clinical experimental autoimmune encephalomyelitis in H-2(b) and H-2(s) mice.

To investigate the immunogenicity and encephalitogenicity of oligodendrocyte-specific protein (OSP), recombinant soluble mouse OSP (smOSP) was produced from a synthetic gene engineered to lack the sequences coding for the hydrophobic transmembrane domains of the native molecule. SmOSP was immunogenic and encephalitogenic for SJL/J, C3H.SW and C57BL/6J mice, but not PL/J or BALB/c mice. SmOSP-specific T-cells from SJL/J, C3H.SW and C57BL/6J mice induced severe chronic clinical experimental autoimmune encephalomyelitis upon transfer. These findings indicate that autoimmune T-cell responses to OSP should be investigated in the context of multiple sclerosis.

Amino Acid Sequence↗
PubMed2000

The central nervous system-specific myelin oligodendrocytic basic protein (MOBP) is encephalitogenic and a potential target antigen in multiple sclerosis (MS).

Uncovering primary target antigens in multiple sclerosis (MS) is of major significance for understanding the etiology and pathophysiology of the disease, and for designing immunospecific therapy. In this study, a synthetic peptide representing a predicted T cell epitope on myelin oligodendrocytic basic protein (MOBP) was found to be encephalitogenic in C3H.SW mice, inducing experimental autoimmune encephalomyelitis with an abrupt onset. Two separate preliminary studies with MOBP peptides indicated that autoreactivity to MOBP occurs in MS. These data strongly suggest that MOBP is a highly relevant target in MS and further point to the complexity of antigen specificities in MS.

Amino Acid Sequence↗
PubMed2000

[Solid and papillary pancreatic neoplasm].

Solid and papillary neoplasm of the pancreas is an interesting and rare malignant tumor. It occurs most commonly in young women. It was first described in 1959 and since then has been referred to by different names, including solid and cystic tumor, solid and cystic epithelial neoplasms, and others. Its malignant potential is low and metastasis is very rare. Treatment includes partial pancreatectomy with full resection of the tumor. The prognosis is generally very good. We present 3 women (aged 17, 19, 39) diagnosed and treated for solid and papillary neoplasm of the pancreas. The unique clinical, histological, and epidemiological characteristics of this tumor are detailed.

Adolescent↗
PubMed2000

Mice overexpressing Bcl-2 in their neurons are resistant to myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE).

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) characterized by destruction of myelin. Recent studies have indicated that axonal damage is involved in the pathogenesis of the progressive disability of this disease. To study the role of axonal damage in the pathogenesis of MS-like disease induced by myelin oligodendrocyte glycoprotein (MOG), we compared experimental autoimmune encephalomyelitis (EAE) in wild-type (WT) and transgenic mice expressing the human bcl-2 gene exclusively in neurons under the control of the neuron-specific enolase (NSE) promoter. Our study shows that, following EAE induction with pMOG 35-55, the WT mice developed significant clinical manifestations with complete hind-limb paralysis. In contrast, most of the NSE-bcl-2 mice (16/27) were completely resistant, whereas the others showed only mild clinical signs. Histological examination of CNS tissue sections showed multifocal areas of perivascular lymphohistiocytic inflammation with loss of myelin and axons in the WT mice, whereas only focal inflammation and minimal axonal damage were demonstrated in NSE-bcl-2 mice. No difference could be detected in the immune potency as indicated by delayed-type hypersensitivity (DTH) and T-cell proliferative responses to MOG. We also demonstrated that purified synaptosomes from the NSE-bcl-2 mice produce significantly lower level of reactive oxygen species (ROS) following exposure to H2O2 and nitric oxide (NO) than WT mice. In conclusion, we demonstrated that the expression of the antiapoptotic gene, bcl-2, reduces axonal damage and attenuates the severity of MOG-induced EAE. Our results emphasize the importance of developing neuroprotective therapies, in addition to immune-specific approaches, for treatment of MS.

Animals↗
PubMed2000

[Treatment of sputum retention by minitracheostomy].

Maintenance of bronchopulmonary hygiene is mandatory for preventing complications of respiratory therapy in the hospitalized patient. Removal of secretions from the tracheobronchial tree is crucial. Conventional therapy, designed to assist in dislodging airway secretions, includes chest physical therapy, incentive spirometry, transnasal endotracheal suctioning and bronchoscopy. Minitracheostomy was first described by Matthews and Hopkinson for recurrent endotracheal suctioning in 1984. Since then there have been few papers about it, but they report good results with low morbidity. Despite this, its use is not popular in routine clinical work. We report our experience with minitracheostomy in the prevention of sputum retention. We conclude that its use is easy, safe and very effective in preventing postoperative and post-traumatic respiratory complications.

Adult↗
PubMed1999

A novel antigen-toxin chimeric protein: myelin basic protein-pseudomonas exotoxin (MBP-PE 40) for treatment of experimental autoimmune encephalomyelitis.

Myelin basic protein (MBP), is a major component of the central nervous system (CNS) myelin. MBP can stimulate T cells that migrate into the CNS, initiating a cascade of events that result in perivascular infiltration and demyelination. EAE is an inflammatory and demyelinating autoimmune disease of the CNS that serves as a model for the human disease Multiple Sclerosis (MS). Taking advantage of the fact that EAE can be mediated by T cells, able to recognize MBP or its peptides, we developed a new approach to target anti-MBP T cells by fusing an MBP-sequence to a toxin. In the new chimeric protein, an oligonucleotide coding for the guinea pig MBP encephalitogenic moiety (residues 68-88) was fused to a cDNA encoding a truncated form of the PE gene (PE40). The chimeric gene termed MBP-PE was expressed in E. coli and highly purified. MBP-PE chimeric protein was cytotoxic to various anti-MBP T cells. Moreover, treatment with the novel MBP-toxin blocked the clinical signs of EAE as well as CNS inflammation and demyelination. A chimeric protein such as MBP-PE40 presents a novel prototype of chimeric proteins, composed of antigen/peptide-toxin, that could prove to be an efficient and specific immunotherapeutic agent for autoimmune diseases in which a known antigen is involved.

ADP Ribose Transferases↗
PubMed1999

Experimental autoimmune encephalomyelitis induced in B6.C-H-2bm12 mice by myelin oligodendrocyte glycoprotein: effect of MHC class II mutation on immunodominant epitope selection and fine epitope specificity of encephalitogenic T cells.

The effect of the bm12 mutation on susceptibility to MOG-induced EAE, TCR repertoire and fine epitope specificity of the encephalitogenic T-cells, was assessed. prMOG35-55 was encephalitogenic for H-2bm12 and H-2b mice. Despite only minor differences in TCRVbeta expression and fine epitope specificity, H-2bm12/ and H-2b/prMOG35-55-specific T-cells failed to recognize Ab/prMOG35-55 and Abm12/prMOG35-55, respectively. rhMOG-induced EAE was milder in H-2bm12 mice, possibly as a result of co-dominant responses to prMOG35-55 and to the non-encephalitogenic pMOG94-116, rather than a single dominant response to prMOG35-55 in H-2b mice.

Amino Acid Sequence↗