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Biomedical subjects

H Behrendt

Publications and source records attributed to H Behrendt.

At least 163 records · Page 9Linked to original sources
PubMed1984

Repeated exposition to subinhibitory concentrations of antibiotic in vitro readily decreases susceptibility of Neisseria gonorrhoeae to rifampicin, but not to new cephalosporins and penicillin G.

Repeated subcultivation of Neisseria gonorrhoeae in the presence of subinhibitory concentrations of antibiotic has turned out as a reliable model to predict the low potential for development of resistance with respect to the beta-lactam antibiotic penicillin. Before large-scale introduction of the new cephalosporins we exposed 5 N. gonorrhoeae strains of different susceptibility to penicillin repeatedly to subinhibitory concentrations of cefotiam, ceftizoxime, rifampicin and penicillin G incorporated into chocolate agar. each time the most resistant representatives of a strain were propagated, on the whole 25 times. While resistance to rifampicin increased readily (all strains became relatively resistant, MIC = 4 micrograms/ml), the same was not true of the cephalosporins. Although their susceptibility decreased, too, no strain acquired partial or even total resistance (final MIC less than or equal to 0.128 with cefotiam and ceftizoxime). The cephalosporins thus rather parallelled penicillin G which hardly induced any increase of resistance. Thus, a quick loss of clinical efficacy need not be feared after large-scale introduction of the new cephalosporins into the therapy of gonorrhea.

Anti-Bacterial Agents↗
PubMed1983

Immunological typing of acute lymphoblastic leukaemia.

The blasts of 37 adult and 126 childhood cases of acute lymphoblastic leukaemia (ALL) were characterized with a panel of xeno-antisera and rosette tests. The Orthoclone monoclonal antibodies (OK series) were applied as well. Like other investigators, we were able to distinguish 4 major classes of ALL: T-ALL, common-ALL with the subclass pre-B-ALL, null-ALL, and B-ALL. We did not encounter a common-ALL antigen-positive T-ALL subclass. In both adult and childhood ALL, all classes were present, and in about the same frequency as reported by others. In children, common-ALL was the most frequent (66%); in adults, null-ALL (38%). T-ALL was seen both in adults and in children with about the same frequency (27 and 23%, respectively). We found pre-B-ALL only in children. Patients with B-ALL comprised the smallest group in both adult and children (8 and 1.5%, respectively). The application of the OKT antibodies led to recognition of 3 major subclasses of T-ALL: an immature, a common thymocyte and a mature thymocyte subclass. These antibodies were helpful in defining a better classification of null-ALL. With regard to remission induction and prognosis in adult ALL, complete remissions were always obtained in T-ALL, followed by 70% of complete remissions in common-ALL. The worst prognosis was encountered in null-ALL and B-ALL, with 50 and 0% remission, respectively, and a shorter survival in null-ALL of those patients who achieved complete remission. Thus, in high number of cases of null-ALL in adults partly explains the generally much worse prognosis for adult ALL.

Adolescent↗
PubMed1983

[Staging of testicular cancer by ultrasound and tumor markers with special respect to stage I and IIA].

In 1976, we began using ultrasound for staging of the retroperitoneal status in patients with testicular cancer. Determinations of tumor markers AFP and beta-HCG were done in all patients. Up to 1981 these investigations were followed by retroperitoneal lymphadenectomy in 148 patients. Ultrasound staging had an over-all accuracy of 79% (n = 117). From 31 incorrect results of sonographic staging there were 29 falsely negative findings in the surgical-pathologic stage IIA with only minimal retroperitoneal disease. Because of this fact the sensitivity of sonographic staging was only 67%, the specificity was 98%. Differentiation between stage I and IIA proved to be very difficult. In this group (stage I and IIA; n = 104) the over-all accuracy was 71%, the sensitivity was only 40%, the specificity was 98%. Adding the results of tumor marker determinations to the sonographic findings, we got a staging error of 41.7% in the stage IIA. Retroperitoneal lymphadenectomy and histologic analysis of the removed nodes thus remains the only reliable staging system for early nonseminomatous testicular cancer.

Adolescent↗
PubMed1983

[Limitations of tumor marker surveillance after chemotherapy in advanced non-seminomatous testicular tumors].

Determination of the biochemical tumor markers, alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (beta-HCG) gained much importance in respect to staging and follow-up examination of patients presenting with testicular cancer. After cytostatic chemotherapy the reliability of tumor markers is diminished. Retroperitoneal lymphadenectomy (RLA) was done in 60 patients after chemotherapy. Tumor marker elevation was found only in 52% of the patients showing retroperitoneal carcinoma (n = 25).

Antineoplastic Agents↗
PubMed1983

Chromosome studies on acute nonlymphocytic leukaemia in children.

Cytogenetic studies have been carried out on 17 children with acute nonlymphocytic leukaemia (ANLL). Of the 16 patients analysed at diagnosis, 11 had acquired clonal chromosome abnormalities. Four out of seven cases with acute myeloid leukaemia (M2) had 8;21 translocations, two of which were variants. Comparisons with other data on ANLL confirmed the association between the 8;21 translocation and the younger age groups. There are indications that the Netherlands may be a high incidence area for this translocation. Differences in the type of chromosome anomalies between childhood and adult ANLL were evident suggesting that different aetiologic factors may be involved.

Adolescent↗
PubMed1983

Cell kinetic responses in childhood acute nonlymphocytic leukemia during high-dose therapy with cytosine arabinoside.

Sequential bone marrow aspirates obtained from 10 children with relapsed acute nonlymphocytic leukemia (ANLL) after a high dose of cytosine arabinoside (Ara-C; 1000 mg/sq m) were analyzed by flow cytophotometry. The drug causing elimination of proliferating cells followed by a synchronous wave of cell recruitment. Among individual patients, considerable variation was observed in the degree of recruitment as well as in the time of appearance of the recruitment maximum (range 17-36 hr). However, both parameters appeared inversely correlated with the proliferative status in the bone marrow before treatment. In 6 other patients, cell kinetic responses were studied during treatment with repeated Ara-C injections scheduled individually according to the expected optima of recruitment. Waves of recruitment could be observed during 4-5 consecutive injections. The results suggest that in childhood ANLL, characteristic and individual cytokinetic responses to treatment with high-dose Ara-C can be monitored during therapy. These observations may allow the development of individual treatment schedules.

Acute Disease↗
PubMed1982

Cytogenetic studies on four cases of non-endemic Burkitt lymphoma.

Cytogenetic studies carried out on four children with non-endemic Burkitt lymphoma showed: 1) Two with the typical translocation t(8;14)(q24;q23); 2) one with a variant t(2;8)(p11;q24); and 3) one with apparently normal chromosomes 8 and 14. Additional chromosomal variation was present in all four patients. Two were shown to have a duplication of part of the long arm of chromosome 1 (1q23 leads to 1q32 and 1q23 leads to 1q42). Epstein Barr virus studies on two patients showed that one was positive and the other negative. A comparison of these results with other non-endemic cases in the literature has been made revealing a wider range of chromosomal variation than has been hitherto reported for endemic cases. The finding that chromosome 8 is also involved in the variant translocations in Burkitt lymphoma suggests that its changes may contribute more to the tumour development than the than the 14q+.

Bone Marrow↗
PubMed1982

Current status of melanoma chemotherapy and immunotherapy.

In the search for an improved prognosis in malignant melanoma after radical surgery, randomized trials arae being conducted examining the results of immunostimulation (BCG or levamisole) with chemotherapy dimethyl - triazeno - imidazole - carboxamide (DTIC) in stage I melanoma. So far, no significant differences between the groups are evident. In stage III melanoma, a series of new agents are being rapidly screened and some appear promising. A closer look at the basic immunopathologic process during the growth of melanomas is might lead to a more effective control of this malignancy.

Clinical Trials as Topic↗
PubMed1982

Comparative studies of mast cells from normal (non-immunized) and actively sensitized dogs.

Morphologically and functionally intact mast cells were isolated from the lung and mesentery of normal or actively sensitized dogs using the pronase or collagenase tissue dissociation methods. The latter method yielded about 6 times as many metachromatically staining cells. Electron microscopic examination revealed the presence of both mast cells and basophils in all samples, independent of the enzyme used for tissue dissociation. The average histamine content of the cells obtained with the pronase method was significantly higher (21.8 +/- 3.1 pg) than after collagenase treatment (16.2 +/- 4.2 pg). There was no appreciable difference in the reactivity to secretory stimulation of the cells obtained by the two methods. The cells isolated from actively sensitized dog tissues showed a significantly higher spontaneous histamine release (12.9 +/- 1.2%) than those from non-sensitized animals (7.8 +/- 1.3%) and responded equally well to challenge with both the antigens ovalbumin and horse serum. In contrast to those from normal animals, the mast cells from actively sensitized dogs released histamine on stimulation with acetylcholine, metacholine or atropine. In addition, the response to the threshold concentration of compound 48/80 (10(-6)) was significantly stronger in the sensitized cells. Small molecular polyvinylpyrrolidone (K25) was effective in mast cells from normal and actively sensitized dogs.

Acetylcholine↗
PubMed1982

[Testicular yolk sac tumor in children. Current view on diagnosis and treatment].

5 children with yolk-sac tumor of the testis (= infantile embryonal carcinoma) were admitted to our hospital between 1973 and 1981. Evaluation of serum alpha-fetoprotein concentrations and ultrasonography of the retroperitoneal area proved to be extremely valuable to predict the tumor stage in these children. Therapy consisted of high inguinal orchiectomy, retroperitoneal lymphadenectomy and cytostatic chemotherapy in 3 children using the T2-protocol. All children are now between 1 1/2 and 8 years free of recurrence and metastases. Therapy of this tumor ought to be differentiated according to the individual tumor stage. Most patients with stage-I tumor require only radical orchiectomy for cure.

Antineoplastic Agents↗
PubMed1982

Characterization of hereditary partial myeloperoxidase deficiency.

We studied a family with a partial myeloperoxidase deficiency. The myeloperoxidase in the neutrophils and monocytes of the parents and their two sons had normal spectral properties (determined optically and by EPR). Enzymic characteristics (oxidation of iodide) were indistinguishable from those of normal myeloperoxidase; moreover, immunological identity between the myeloperoxidase in the leukocytes of the family members and normal myeloperoxidase was found. No differences in heat stability were observed. The neutrophils and monocytes of the sons contained 9% to 18% of the myeloperoxidase content of normal cells; the neutrophils and monocytes of the parents contained 45% to 58%. These data suggest either that the parents are heterozygous and the sons homozygous for hereditary partial myeloperoxidase deficiency or that each parent is heterozygous for a different type of myeloperoxidase deficiency and the sons combine both deficiencies. The oxidative metabolism of the neutrophils during phagocytosis was not affected by the myeloperoxidase deficiency. The killing of Staphylococcus aureus was apparently normal. The perforation of Escherichia coli by the neutrophils of the sons, however, was retarded in comparison with normal neutrophils.

Adult↗
PubMed1982

Effects of Ca2+ deficiency, collagenase, and mechanical dispersion on the ultrastructure of cardiac myocytes of adult rats.

A new perfusion medium for isolating cardiac myocytes from adult rats was developed, thereby yielding numerous viable cells with few morphological changes. The main factors in the isolation procedure are Ca2+ deficiency, collagenase, and mechanical dispersion. Their effects on the ultrastructure of cardiac myocytes were separately tested. In isolated hearts, perfusion with a medium containing a physiological Ca2+ concentration (2.5 mM, controls) preserved the cellular fine structure well, whereas perfusion with a medium containing 2.5 mM Ca2+ plus 0.05% collagenase caused swelling and disruption of most cells. Perfusion with a Ca2+-deficient medium followed by a medium with a low Ca2+ concentration (25 microM) either containing or lacking collagenase resulted in widening of the T-tubules, reduced electron density of the external lamina and occasional separation, or even dissolution of this layer. Some cells were damaged and hypercontracted. These appeared more numerous in suspensions, that means after mechanical dispersion of the myocardium. However, most of the isolated cells were regularly shaped (up to 30-60 min as shown in another study) and their ultrastructure was only slightly altered. This corresponds to an adequate preservation of the cell membranes proven in earlier membrane transfer studies.

Animals↗