PubMed Health⌕ Search

Biomedical subjects

J Bohn

Publications and source records attributed to J Bohn.

At least 19 recordsLinked to original sources
PubMed2003

Distinct expression of calnexin in major human salivary glands.

Calnexin (Cnx) has been characterized as a membrane-bound protein that transiently interacts in a unique chaperone system with newly synthesized glycoproteins in order to allow the establishment of their proper tertiary and, in most cases, quarternary structures. The aim of the study was to identify and to locate the expression of Cnx in the three major salivary glands of humans by different methods. Strong expression of Cnx protein and mRNA were generally found in serous salivary secretory units. With regard to mucous secretory units, expression of Cnx was only detectable at a low level in mucous acinar cells of sublingual glands, but not of submandibular glands. Expression of Cnx was always preserved in the surface epithelium of intralobar and interlobular duct segments. In addition, expression of Cnx was detected in sebaceous glands of parotid tissues, with a distribution pattern resembling that seen in sebaceous glands of the normal skin. In conclusion, production of saliva is associated with the expression of Cnx. Synthesis of molecules in mucous secretory units is not necessarily associated with a strong Cnx expression, whereas synthesis in serous secretory units apparently is. The tissue-specific Cnx expression is also paralleled by the observation that the secretions produced by the major salivary glands differ in their composition and amount.

Blotting, Western↗
PubMed2002

Expression of osteopontin (Eta-1) in Crohn disease of the terminal ileum.

BACKGROUND: The causes of Crohn disease (CD) are still regarded as unknown, but impaired mucosal immunoregulation with activation of T-helper-1 (Th-1) cytokine responses is probably involved and may contribute to the morphological changes. We investigated a possible role of osteopontin (Opn) in the pathogenesis of CD. This glycoprotein has been suggested to be involved in the generation of Th-1-type immune responses; moreover, it carries anti-inflammatory activities. METHODS: Ileal samples from CD patients--both actively inflamed and inactive areas as well as unaffected intestinal specimens from controls (normal ileum)--were investigated by Western blot analysis, immunohistochemistry and in situ hybridization. RESULTS: In normal gut, Opn was found to be regularly expressed by plasma cells (CD 38) and a subset of lamina propria mononuclear cells (MNC) as well as by intestinal epithelial cells (IEC). In active CD, immunohistochemistry and in situ hybridization analysis revealed a loss of Opn expression by IEC adjacent to ulcerative lesions, whereas especially plasma cells (CD 38) in the vicinity of such lesions were found to express the molecule. In addition, a slight overexpression of Opn protein was found in metaplastic crypts. However, quantitative analysis of total Opn protein in the ileal mucosa of CD patients did not reveal any difference vis-à-vis control tissues. CONCLUSIONS: The constitutive expression of Opn in normal gut indicates that it is involved in intestinal immune homeostasis. Downregulation of Opn expression in IEC might favour the disintegration of the epithelial barrier. The expression of Opn in lamina propria plasma cells could contribute to disease chronification, probably by affecting cell survival.

Adult↗
PubMed2001

Surgical treatment of hidradenitis suppurativa.

Hidradenitis suppurativa is a skin disease involving the apocrine sweat glands which often becomes chronic. The aetiology is not completely known, but the mainstays of medical treatment are antibiotics, which gives temporary relief but do not essentially alter the course of the disease. We describe our results of treating 138 affected patients by radical excision of the diseased areas between 1978 and 1999. Postoperative follow-up ranges from 3 months to 21 years; we compiled data from the patients' casenotes and circulated a questionnaire, which 116 patients completed. Median age at onset of disease was 23 years and the interval before radical surgery was 10 years. Altogether 367 affected sites were excised; most cases required skin grafting. There were no serious surgical complications. In 38 patients (33%) the disease recurred to some degree, and 14 of them required further operation. Six patients had a subsequent operation to improve the aesthetic result. Ninety-six of the patients (83%) answered that they would recommend the procedure to other patients under similar circumstances. In our opinion excision and skin grafting is a valuable treatment in cases of severe hidradenitis suppurativa.

Adult↗
PubMed2000

A small synthetic peptide, which inhibits the p53-hdm2 interaction, stimulates the p53 pathway in tumour cell lines.

The hdm2 protein negatively regulates p53 tumour suppressor activity. Upon binding to p53, hdm2 stimulates p53 degradation and inhibits its transcriptional activity. Moreover, the hdm2 protein is overexpressed in various tumours inactivating p53. We report here that an octamer synthetic peptide derived from p53 inhibits the p53-hdm2 interaction in vitro. In cellular assays, this untagged peptide penetrates tumour cells and induces the accumulation of p53. The accumulation of p53 leads to its activation. Two gene products transcriptionally regulated by p53, p21Waf1/Cip1 and hdm2, are induced in the presence of the peptide. When used with tumour cells that overexpress hdm2, the peptide induces the death of these tumour cells by apoptosis. The mode of action of this peptide differs from that of DNA-damaging agents (e.g. cisplatin) in that it does not induce p53 phosphorylation on serine 15. This work validates with a low molecular mass molecule our current knowledge on the regulation of the p53 pathway by the hdm2 protein. It also shows that inhibitors of the p53-hdm2 interaction are very attractive candidates for the activation of the p53 pathway in tumours expressing wild-type p53.

Apoptosis↗
PubMed2000

Clinical comparative study between cryotherapy and local dermabrasion for the treatment of solar lentigo on the back of the hands.

BACKGROUND: Solar lentigo is a common and unsightly dermatosis that has a variety of proposed treatments. OBJECTIVE: This study was done to assess the efficacy and the effectiveness of localized dermabrasion compared with cryotherapy with liquid nitrogen on solar lentigo on the back of the hands. METHODS: Ten female patients aged 64-96 years with solar lentigo on the back of the hands were treated with dermabrasion or cryotherapy and observed over a 6-month period. RESULTS: The postsurgery signs and symptoms were less intense and better tolerated with localized dermabrasion. More than 50% of the patients treated with cryotherapy still had hypochromia in the treated areas 6 months after treatment, compared with 11% of the patients treated with dermabrasion. The percentage of recurrence was the same with the both treatments (55.55%). CONCLUSION: Localized dermabrasion is an efficacious and effective technique comparable to cryotherapy for the treatment of solar lentigo on the back of the hands.

Adult↗
PubMed2000

Dermabrasion of large congenital melanocytic naevi in neonates.

We describe our findings in a series of 12 patients with large congenital melanocytic naevi treated with dermabrasion between the first and fourteenth week of life. Postoperative follow-up ranged from 1-16 years. In all but two cases dermabrasion resulted in an appreciable and stable reduction of the hyperpigmentation, possibly by reducing the number of pigmented cells in the epidermis. In six of our 12 patients, reconstruction using grafts and flaps was done to improve the aesthetic result. Seven years after dermabrasion, one patient developed a minimal deviation melanoma in the treated area, but his subsequent clinical course has been uneventful.

Adolescent↗
PubMed1999

Are natural antibodies involved in tumour defence?

Natural antibodies (NAb) are found in the serum of healthy individuals. These antibodies are produced without any apparent specific antigenic stimulation. They are one part of the circulating immunoglobulins and are found in virtually all vertebrate species. NAb react to various self- and non-self antigens. A protective function in different infection models could be demonstrated. Several groups have reported the ability of NAb to bind to tumour cells. Their possible role in tumour defence is documented in mice. The present status of attempts to characterise the role of NAb in tumour defence is discussed, particularly as regards the human immune system. This paper focuses on antibody cell interactions and discusses the genetic background of the Nab-producing B-cells.

Animals↗
PubMed1999

Successful treatment of recalcitrant cicatricial pemphigoid with a combination of plasma exchange and cyclophosphamide.

We describe two patients with severe oral cicatricial pemphigoid, one of whom also had severe pharyngeal involvement. Both patients were resistant to treatment with corticosteroids and other standard immunosuppressive therapies. Plasma exchange alone proved to be only temporarily effective, but the combination of plasma exchange with subsequent cyclophosphamide resulted in a remission in both patients. Both patients experienced mild side-effects during the plasma exchange treatment (urticaria and mild hypotension). At present, at follow-up of 6 and 9 years, respectively, the patients have no symptoms of active disease and have not required any further immunosuppressive treatment.

Cyclophosphamide↗
PubMed1996

[Atypical initial manifestation of Takayasu arteritis].

Primary clinical manifestations in patients with Takayasu arteritis are mostly unspecific signs of inflammation. First involved are the main brachiocephalic arteries and the aorta. Later the disease becomes symptomatic through organ ischemia. Often a renal hypertension appears due to an arteritic stenosis of the renal artery. Here we present a patient suffering from Takayasu arteritis. The disease first appeared with renal hypertension and an encephalopathy. The hypertension was induced by compression of the right renal artery which in turn was caused by an aortic aneurysm. The aneurysm had been resected and the aorta was reconstructed by aorto-aortal prosthetic interposition and implantation of the renal arteries. The postoperative course was uneventful.

Adult↗
PubMed1995

Tumour cell binding by a human monoclonal IgM antibody from the spleen of a non-tumour-associated patient is due to somatic mutations in the VH gene.

Recently we described the occurrence of B cells producing polyspecific natural IgM with anti-tumour specificity in the spleen of non-tumour-bearing individuals as well as in fetal organisms. Immunoprecipitation and 2-D electrophoresis showed the binding of such antibodies to a 55-kD (pI 6.0) membrane surface glycoprotein. In vitro cultivation of human cancer cell lines in the presence of the purified IgM antibodies resulted in growth inhibition and complement-mediated cell lysis. Furthermore, the antibodies were shown to be able to induce MHC class I molecule expression on tumour cells. Because of this, a role for naturally occurring antibodies with anti-tumour specificity in preventing neoplasias had been suggested. We have constructed and expressed in Escherichia coli single-chain fragments (scFv: VH-linker-VL) derived from a polyspecific human monoclonal IgM autoantibody produced by a human x mouse heterohybridoma which was obtained from the spleen of an autoimmune patient. The mutated complementarity determining region (CDR) gene segments were replaced by the equivalent germ-line sequences and the CDR3 region was swapped for that from another polyspecific human natural antibody with no binding to tumours. Using these four scFv constructs for binding analyses and in vitro cultivation experiments we found: (i) scFv containing the mutated VH region of the original antibody were able to bind to tumour cells, to induce MHC class I molecule expression, and to inhibit tumour growth in a way similar to what had been described for the complete antibody; (ii) replacement of the mutated by the germ-line VH gene independently of the CDR3 to which it had been recombined, resulted in failure to bind to tumour cells. Nevertheless, other antigens (ssDNA, tetanus toxin) were still recognized, although with lower affinity. We discuss the significance of the replacement mutations in the VH gene CDRs, selected probably by B cell contact to an (auto)antigen, for generating a tumour binding capacity, not encoded by the germ-line gene.

Amino Acid Sequence↗
PubMed1994

Binding of natural human IgM auto-antibodies to human tumor cell lines and stimulated normal T lymphocytes.

In a recent publication we described the binding of natural IgM antibodies derived from the human fetal B cell repertoire to the cell surface of some human tumor cells including colon carcinoma, small-cell lung cancer and B lymphoma lines [1]. Further analyses showed that a similar molecule was bound by the respective monoclonal human antibodies on the cell surface of polyclonally stimulated human CD3+ T cells, but is absent from unstimulated MNC. Both CD4+ and CD8+ stimulated cells were recognized. The molecule was found to be expressed together with lymphocyte activation markers (4F2, CD72, CD25). The membrane antigen expressed on both the activated T lymphocytes and tumor cells was characterized in a 2-D electrophoresis system: molecular weight 55-60 kDa, pI-approximately 6.0. Whereas the proliferation capacity of tumor cells was detected to be decreased significantly in the presence of the binding antibodies, no influence on [3H]thymidine uptake into stimulated T cells was found, suggesting different functional consequences of binding the respective antigen on malignant and normal cells. An interesting finding is the enhanced expression of major histocompatibility complex class I molecules on tumor cells incubated with human natural antibodies.

Antigens, Surface↗
PubMed1994

VH/VL gene expression in polyreactive-antibody-producing human hybridomas from the fetal B cell repertoire.

Among a panel of nearly 3,000 IgM-producing hybridomas obtained from 22 independent fusions of human fetal lymphocytes (liver/spleen; 15th-36th gestational week) a high number (5-10%) produced autoantibodies, independently of the gestational age. A significant portion of these autoantibodies was found to be polyreactive, i.e. capable of binding to more than two antigens, when tested against a set of five antigens of the internal (ssDNA, thrombocytes, keratin) and external (lipid A, tetanus toxoid) environment. Analyzing the IgVH genes utilized in eight polyreactive and two putatively nonpolyreactive hybridomas, members of the VHI, III, IV and VI families were found once, seven times, once and once, respectively, mostly with germline identity. All but one of the utilized gene elements could be related to the biased VH gene repertoire said to be expressed during the early ontogeny of the human immune system. We also noted a bias for the utilization of DN1 (3/10), DHQ52 (3/10), JH2 (4/10) and JH6 (4/10) elements, whereas all heavy-chain CDR3 regions manifest a diversity by addition of N nucleotides and/or exonuclease activity on coding segments. In addition, VL segments which belong to different subgroups of both isotypes were found to be used. The molecular basis of polyreactive immunoglobulin specificities in human fetuses is discussed.

Antibodies, Bispecific↗
PubMed1983

[Non-invasive determination of the enddiastolic volume of the left ventricle. A comparative angiocardiographic, two-dimensional echocardiographic, computer tomographic and radionuclide ventriculographic study].

60 patients underwent left ventricular angiography (CV) and/or two-dimensional echocardiography (2DE) and/or multiple-gated equilibrium angiography (MUGA) and/or computer-tomography (CT) for determination of the left ventricular end-diastolic volume. Estimation of the enddiastolic volume from the various measurements showed significant correlations: CV/2DE: y equal 0.839 x +6.10, r equal 0.93, SEE equal 34.2 ml; CV/CT: y equal 0.762 x +30.30, r equal 0.82, SEE equal 20.8 ml; CV/MUGA: y equal 0.992 x +20.53, r equal 0.97, SEE equal 31.4 ml; 2DE/CT: y equal 1.167 x +19.58, r equal 0.93, SEE equal 38.4 ml; 2DE/MUGA: y equal 1.068 x +37,79, r equal 0.90, SEE equal 52.1 ml. Our study demonstrates that noninvasive techniques for measurement of the enddiastolic volume give results comparable to those obtained by cardiac catheterization. In addition, it is of interest that the noninvasive techniques examined show good agreement with each other.

Angiocardiography↗