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Biomedical subjects

E van Dijk

Publications and source records attributed to E van Dijk.

At least 19 recordsLinked to original sources
PubMed1998

Donor-specific hyporeactivity after liver transplantation: prominent decreases in donor-specific cytotoxic T lymphocyte precursor frequencies independent of changes in helper T lymphocyte precursor frequencies or suppressor cell activity.

BACKGROUND: The development of immunological donor-specific hyporeactivity may account for the low incidence of chronic rejection after clinical liver transplantation. We investigated whether hyporeactivity commonly develops after liver transplantation by analyzing precursor frequencies of donor-reactive cytotoxic (CTLp) and helper (HTLp) T lymphocytes and mixed lymphocyte culture (MLC) reactivity in liver allograft recipients. We further studied whether CTLp hyporeactivity correlated with changes in donor-specific HTLp frequencies or suppressor cell activity. METHODS: CTLp and HTLp frequencies and MLC reactivity against donor and third-party spleen cells were determined in pre- and posttransplantation peripheral blood samples from 18 recipients with good graft function 2 years after transplantation. By mixing posttransplantation samples (with "putative" suppressor cell activity) with pretransplantation samples (in which normal CTL activity with no suppressor cell activity is expected), the presence of suppressor cell activity in peripheral blood was analyzed. RESULTS: Two years after transplantation, all but one (94%) of the recipients had developed CTLp hyporeactivity as evidenced by reduced donor-specific CTLp frequencies. The development of hyporeactivity was not specific for any particular underlying disease. The occurrence of HTL hyporeactivity, however, was less frequent: 38% and 20% of recipients were HTLp and MLC hyporeactive, respectively. Decreases in CTLp frequencies did not correlate with decreased donor-specific HTL function or suppressor cell activity in peripheral blood samples. CONCLUSIONS: Donor-specific CTLp hyporeactivity can develop in the majority of liver allograft recipients, irrespective of underlying disease. Donor-specific HTL hyporeactivity, however, occurs infrequently. A reduction in donor-specific CTLp frequencies was found to be independent of changes in donor-specific HTLp or suppressor cell activity, suggesting that other mechanisms (e.g., clonal deletion) are operative in the reduction of donor-specific CTLp after liver transplantation.

Humans↗
PubMed1998

Donor-specific immunological non-responsiveness after liver transplantation.

Since the rate of immunological losses of liver allograft after the immediate posttransplant period is much lower than in other organs, we studied the immune responses against donor HLA antigens in 18 patients with a good long-term outcome to determine whether the development of a state of immunological non-responsiveness to donor antigens might account for this favorable outcome. The reactivity against donor spleen cells was measured before and 2 years after transplantation. The reactivity in mixed lymphocyte culture (MLC) and the frequencies of cytotoxic T cell precursors (CTLp) were determined. Responses against third-party spleen cells were determined concurrently to exclude a generalized reduction of immunocompetence due to chronic immunosuppressive treatment. Before orthotopic liver transplantation, the majority of patients had normal T cell responses against donor antigens that were comparable to those against third-party antigens. Two years after transplantation, donor-specific MLC non-reactivity had developed in 10 of the 18 (56%) patients. In addition, 15 of 18 (83%) patients had developed donor-specific cytotoxic T cell (CTL) non-responsiveness; 2 had reduced numbers of CTLp against both donor and third-party cells, while the remaining patient had maintained reactivity against donor antigens. In conclusion, donor-specific non-responsiveness is present in the majority of patients 2 years after successful liver transplantation, but occurs predominantly at the CTL level.

Humans↗
PubMed1998

Correction factors for the NMi free-air ionization chamber for medium-energy x-rays calculated with the Monte Carlo method.

A new method is described for the determination of x-ray quality dependent correction factors for free-air ionization chambers. The method is based on weighting correction factors for mono-energetic photons, which are calculated using the Monte Carlo method, with measured air kerma spectra. With this method, correction factors for electron loss, scatter inside the chamber and transmission through the diaphragm and front wall have been calculated for the NMi free-air chamber for medium-energy x-rays for a wide range of x-ray qualities in use at NMi. The newly obtained correction factors were compared with the values in use at present, which are based on interpolation of experimental data for a specific set of x-ray qualities. For x-ray qualities which are similar to this specific set, the agreement between the correction factors determined with the new method and those based on the experimental data is better than 0.1%, except for heavily filtered x-rays generated at 250 kV. For x-ray qualities dissimilar to the specific set, differences up to 0.4% exist, which can be explained by uncertainties in the interpolation procedure of the experimental data. Since the new method does not depend on experimental data for a specific set of x-ray qualities, the new method allows for a more flexible use of the free-air chamber as a primary standard for air kerma for any x-ray quality in the medium-energy x-ray range.

Air↗
PubMed1995

Peptide vaccine against canine parvovirus: identification of two neutralization subsites in the N terminus of VP2 and optimization of the amino acid sequence.

The N-terminal domain of the major capsid protein VP2 of canine parvovirus was shown to be an excellent target for development of a synthetic peptide vaccine, but detailed information about number of epitopes, optimal length, sequence choice, and site of coupling to the carrier protein was lacking. Therefore, several overlapping peptides based on this N terminus were synthesized to establish conditions for optimal and reproducible induction of neutralizing antibodies in rabbits. The specificity and neutralizing ability of the antibody response for these peptides were determined. Within the N-terminal 23 residues of VP2, two subsites able to induce neutralizing antibodies and which overlapped by only two glycine residues at positions 10 and 11 could be discriminated. The shortest sequence sufficient for neutralization induction was nine residues. Peptides longer than 13 residues consistently induced neutralization, provided that their N termini were located between positions 1 and 11 of VP2. The orientation of the peptides at the carrier protein was also of importance, being more effective when coupled through the N terminus than through the C terminus to keyhole limpet hemocyanin. The results suggest that the presence of amino acid residues 2 to 21 (and probably 3 to 17) of VP2 in a single peptide is preferable for a synthetic peptide vaccine.

Amino Acid Sequence↗
PubMed1989

[Diagnosis of dermatomycoses using the sellotape-KOH method].

In a group of 84 adult male workers in an industrial plant, who used a common shower room, the applicability of the adhesive tape-KOH technique for routine mycologic examination was investigated. The tape technique was compared with the conventional cover slip technique in interdigital and plantar lesions. The tape technique gave more frequent positive results than the cover slip technique (74% and 57% respectively). However, examination of the tapes was more difficult than that of the cover slips. The latter method therefore appears more appropriate for routine microscopical mycologic examination.

Adult↗
PubMed1989

Systemic therapy with fumaric acid derivates: new possibilities in the treatment of psoriasis.

For the past two decades fumaric acid (FA) therapy has become an increasingly popular treatment in Western Europe for psoriasis. FA therapy originally was developed by Schweckendiek and subsequently standardized by Schäfer. Schäfer's fumaric acid compound therapy (FACT) consists of the oral intake of dimethylfumaric acid ester (DMFAE) and several salts of monoethylfumaric acid ester (MEFAE) in combination with topical fumaric acid therapy (1% to 3% MEFAE in an ointment or FA in bathing oils) and a diet. Schäfer claimed excellent results in a large number of patients. Preliminary studies by German dermatologists, however, revealed contradictory therapeutic results and serious side effects, and FA treatment was soon abandoned by dermatologists. To assess the value of FA therapy we conducted an open pilot study of 36 patients in which FACT therapy appeared to be rather effective. Thereafter, several controlled studies with MEFAE sodium in two different dosages versus placebo, and DMFAE versus placebo, were done. The results indicated that MEFAE sodium in dosages up to 240 mg daily was ineffective, whereas daily dosages of 720 mg resulted in a significant decrease in scaling and itching but did not affect extension of the eruption. DMFAE, 240 mg daily, produced a significant amelioration and prevented extension. Side effects of FA treatment were nausea, diarrhea, general malaise, and severe stomachache. Mild disturbances of liver and kidney function during treatment were observed with the 720 mg dosage of MEFAE and with the 240 mg dosage of DMFAE. Moreover, a relative lymphopenia with a selective decrease of suppressor T lymphocytes occurred in about 50% of the patients treated with DMFAE.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1988

Geographic stomatitis and psoriasis.

5 new cases of geographic stomatitis are presented and added to a review of 32 similar cases reported in the literature up to 1987. Furthermore, a series of 70 consecutive patients with psoriasis were examined for oral mucosal lesions. Based upon the findings of the literature and the results of the present study, there seems insufficient proof to consider geographic stomatitis an oral manifestation of psoriasis.

Adolescent↗
PubMed1988

To perfuse or not to perfuse? A retrospective comparative study to evaluate the effect of adjuvant isolated regional perfusion in patients with stage I extremity melanoma with a thickness of 1.5 mm or greater.

The use of isolated regional perfusion in an adjuvant setting for stage I melanoma of the extremity continues to be controversial. The present retrospective study evaluates the past 20 years' experience by comparing 227 perfused patients from Groningen with 238 matched controls from five hospitals in The Netherlands and Westphalia (a region of West Germany bordering the Netherlands). All patients underwent wide local excision for a primary extremity melanoma of 1.5 mm or greater in thickness. A proportional hazards regression analysis for recurrence of disease and survival identified the significant prognostic factors, of which tumor thickness was the most important. Corrected for these factors, it was not possible to demonstrate a statistically significant effect for perfusion in terms of time to limb recurrence (P = .61), time to regional lymph node metastasis (P = .11), time to distant metastasis (P = .73), disease-free interval (P = .42), and survival (P = .90). No statistically significant differences were seen for adjuvant perfusion in any of the subgroups.

Adult↗
PubMed1987

Experimental verification of the air kerma to absorbed dose conversion factor Cw,u.

In a recently published code of practice for the dosimetry of high-energy photon beams, the absorbed dose to water is determined using an ionization chamber having an air kerma calibration factor and applying the air kerma to absorbed dose conversion factor Cw,u. The consistency of these Cw,u values has been determined for four commonly employed types of ionization chambers in photon beams with quality varying between 60Co gamma-rays and 25 MV X-rays. Using a graphite calorimeter, Cw,u has been determined for a graphite-walled ionization chamber (NE 2561) for the same qualities. The values of Cw,u determined with the calorimeter are within the experimental uncertainty equal to Cw,u values determined according to any of the recent dosimetry protocols.

Calorimetry↗
PubMed1987

Is pseudoepitheliomatous, micaceous and keratotic balanitis synonymous with verrucous carcinoma?

Two cases of pseudoepitheliomatous, micaceous and keratotic balanitis are presented and their clinical and histological features are discussed. This rare condition of the glans penis was originally thought to be benign, but more recent evidence indicates that the lesion is a manifestation of verrucous carcinoma. Consequently, the treatment of choice is excision with a wide margin. We suggest the new name, micaceous and verrucous malignant balanitis.

Aged↗
PubMed1986

The enigma of juvenile plantar dermatosis.

Juvenile plantar dermatosis, which is sometimes accompanied by palmar changes, is a chronic condition. It is characterized by shiny redness, anhidrosis, and fissuring of the skin. Microscopically, focal inflammatory changes at the junctions of sweat-gland ducts and acrosyringia are seen. The pathogenesis is unknown. We surmise that individual susceptibility, bacterial colonization, and the use of man-made leather substitutes and fibers are the main causative factors.

Adolescent↗
PubMed1985

Acrokeratoelastoidosis: a spectrum of diseases.

Two familial cases of acrokeratoelastoidosis (AKE) are reported. As a quite uncommon feature, both showed a distinct violaceous hue in addition to the characteristic clinicopathological changes. Furthermore a case of keratoelastoidosis marginalis of the hands, also showing involvement of the feet, is described. This latter syndrome may cause confusion with AKE, but appears to be a separate entity. The classification of AKE is discussed. It is suggested that AKE is a syndrome with a broad spectrum of clinical and histological abnormalities.

Adult↗
PubMed1985

Group therapy of psoriasis. Duo formula group treatment (DFGT) as an example.

Between 1978 and 1982 an experiment on group treatment for and by psoriasis sufferers was conducted, based on a pyramid of previous investigations since 1968. Each group was facilitated by a duo consisting of a fellow sufferer and a physician, both having trained together. The subjects practiced the procedure described, directed toward self-care and mutual aid facilitated and supported by the duo, in a series of ten 2-hour weekly sessions. A pretest/posttest control group design was used. Comparing the results of the quantitative analysis of the experimental groups with those of the control groups, the experimental groups showed significant change. The results of the qualitative analysis showed that decrease of anxiety correlated with mastering of the skills involved. The key element affecting outcome was the balance in cooperation within the duo, the expertise of the patient lying in his personal experience of the condition, and the expertise of the physician in his knowledge and skills. One of the method's main characteristics was the intrinsic complementarity of the duo partners.

Aged↗
PubMed1985

[Group treatment of psoriasis with the duo formula].

Group treatment for and by psoriasis patients was the subject of a trial. For 12 sessions over a period of 3 months, a fellow sufferer as co-helper cooperated with a professional specialist as co-worker according to the so-called duo formula. When the results were compared with those in a control group, the patients showed a change in the dimensions examined, as well as in their illness behaviour and insight into the value of problem-solving in groups. Therefore, it is recommended that dermatologist/co-helper teams be instructed for group treatment of chronic skin diseases, because this method stimulates self-activity in patients.

Adult↗