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Biomedical subjects

B Klein

Publications and source records attributed to B Klein.

At least 451 records · Page 25Linked to original sources
PubMedDate not supplied

SEM observations on the effect of anthracycline drugs on cultured newborn rat cardiomyocytes.

The effect of two anthracyclines-doxorubicin hydrochloride (adriamycin) and 4'-epidoxorubicin (epirubicin) and an anthracenedione (novantrone) on the contractibility and surface ultrastructure of newborn rat cardiomyocytes cultured for five days was examined. While the beating rate of the cells was affected only by the anthracyclines, an alteration of the sarcolemma, disruption of the slender processes and swelling of the nuclei and/or the cells was observed following incubation with each of the three drugs for two hours. However, the damage induced by adriamycin was more pronounced than that induced by the other two drugs, when doses extrapolated from those accepted as therapeutic were compared.

Animals↗
PubMedDate not supplied

Human natural killer cells suppress the proliferation of B cells.

We have investigated the suppressive effect of human natural killer (NK) cells on autologous B-cell proliferation. Removal of NK cells by anti-NK-cell monoclonal antibodies (CD16, Leu 11b; Leu 7) increased by 2-3-fold the proliferative response of purified B cells activated by anti-mu and B-cell growth factor (BCGF). The inhibitory effect of NK cells was observed using recombinant IL-2 or semi-purified BCGF-I as sources of BCGF. Moreover NK cells, highly purified by centrifugation on a Percoll discontinuous density gradient, suppressed the proliferative response of purified autologous B cells activated by anti-mu and BCGF. These results show a suppressive effect of human NK cells on B-cell proliferation in vitro.

Antibodies, Monoclonal↗
PubMedDate not supplied

In vitro interleukin-3 binding to leukemia cells predicts cytotoxicity of a diphtheria toxin/IL-3 fusion protein.

Patients with acute myeloid leukemia frequently develop chemotherapy resistant blasts. To overcome multidrug resistance, a diphtheria toxin fusion protein (DTIL3) was engineered by fusing the catalytic and translocation domains of diphtheria toxin (DT) to human interleukin-3 (IL-3). However, when blasts were isolated from patients and tested for colony growth inhibition by DTIL3, only a third of the samples showed sensitivity to the fusion protein. Prior to clinical development, we need to be able to identify which patients are likely to respond to therapy with DTIL3. In this report, we compared the inhibition of thymidine incorporation in human leukemia cell lines by DTIL3 to the IL-3 receptor number and affinity. We found DTIL3 was cytotoxic to four of the eight cell lines tested with half-maximal inhibition of thymidine incorporation (IC(50)) from 1 to 50 pM. The IL-3 receptor density for these cell lines ranged from 0 to 2635 receptors per cell. The dissociation constant for an IL-3 high-affinity receptor agonist was 0.5 nM for cell lines with receptors. We found a correlation for the cell lines between the presence of high-affinity IL-3 receptors and sensitivity to DTIL3 (p = 0.03). These results suggest the variability in sensitivity of patient leukemic progenitors to DTIL3 may be due in part to the presence or absence of high-affinity IL-3 receptors.

Antineoplastic Agents↗
PubMedDate not supplied

Application of a new dynamic flow model for investigating the biocompatibility of modified surfaces.

An in vitro model was developed to compare the biocompatibility of four different coating methods (three heparin and one nonheparin) under hemodynamic conditions. Fresh human donor blood (heparin 5 IU/ml) was recirculated in a standardized experimental circuit. All circuit components were either coated or remained uncoated for control purposes. The aim of the study was to investigate a wide spectrum of effects on blood; coagulation parameters (e.g., fibrinogen, ATIII, thrombin-antithrombin-complex), complement parameters (C1rsC1 Inh, C3b(Bb)P, SC5b-9, C5a), differential blood analyses, platelet activation (flow cytometric investigations), PF 4, and PMN-elastase release were examined by showing possible trends. All heparin coated systems reduced platelet stimulation in comparison to untreated biomaterials. Leukocyte activation was reduced to different degrees depending upon the coating method used. Complement activation was markedly reduced by all coated systems. The results obtained indicate that the pump driven, dynamic blood flow model is suitable to characterize the biocompatibility of surface modified biomaterials. Advantages lie in the integration of the different polymers as parts of the circuit, the low priming volume, and the generation of blood flow conditions similar to those that occur in clinical applications.

Biocompatible Materials↗
PubMedDate not supplied

Thorn synovitis: CT diagnosis.

A case of monoarticular arthritis due to a retained thorn about the left knee is presented. In this case CT was helpful to localize precisely the thorn within the joint whereas other modalities such as plain films, gallium scan, and 99mTc-methylene diphosphonate bone scan were negative.

Child, Preschool↗
PubMedDate not supplied

Influence of ethnicity and gender on cardiovascular responses to active coping and inhibitory-passive coping challenges.

OBJECTIVE: The goal of this study was to evaluate how black and white men and women responded physiologically to specific laboratory challenges. METHODS: Hemodynamic responses to an active coping (evaluated speaking) and two inhibitory-passive coping (mirror tracing, cold pressor) tasks were examined in 138 black and white men and women. RESULTS: Significant ethnicity by gender interactions occurred for the evaluated speaking task. Black men responded with lower blood pressure, cardiac output or heart rate, or both, than black women, white men, and white women, who did not differ from each other. Black men, relative to the other subgroups, also reported more inhibitory-passive coping, hostility, and pessimism, and less social support. Whites also responded with greater increases in systolic blood pressure during mirror tracing than blacks. CONCLUSIONS: These findings indicate that black-white differences in physiological responsivity obtained for men may have limited generalizability for women. The results also suggest that environmental and social factors rather than genetic or constitutional factors may play a role in black-white reactivity differences.

Adaptation, Psychological↗
PubMedDate not supplied

Induction of gastrointestinal tumors in mice fed the fungicide folpet: possible mechanisms.

Dietary administration of the fungicide folpet, N-(trichloromethylthio) phthalimide, to B6C3F1 mice at dose levels of 1,000, 5,000 and 10,000 ppm induced a dose-related appearance of duodenal atypical hyperplasia, adenomas and adenocarcinomas. The appearance in some of these animals of gastric papillomas and gastric squamous cell carcinomas was correlated in many instances to the presence of duodenal obstructions. It is suggested that the gastric lesions appeared subsequent to, and as an indirect result of, these partial lumenal duodenal obstructions. We suggest that the presence of duodenal obstructions is consistent with the notion that reflux of folpet, bile acids and pancreatic enzymes into the stomach may have acted to irritate and consequently stimulate local neoplastic proliferation. In addition, the duodenal obstructions may have resulted in delayed emptying time of the stomach contents with consequential stagnation. This would cause high concentrations of folpet to act locally on the gastric mucosa.

Adenocarcinoma↗
PubMedDate not supplied

Phagocytotic activity of monocytes from diabetic patients.

The phagocytotic activity of monocytes from diabetic patients and healthy controls was studied. It was found that the number of phagocytizing cells from diabetic patients was significantly reduced in comparison with that from control individuals. However, the number of bacteria phagocytized per cell was similar in both groups. Plasma from healthy controls added to diabetic monocytes did not cause any significant change in their phagocytotic capacity. Addition of insulin to the plasma of diabetic patients failed to alter the number of phagocytizing diabetic monocytes. Similarly, addition of glucose to control plasma did not affect the number of control monocytes capable of phagocytosis. Protein synthesis was increased during phagocytosis in both control and diabetic cells. The importance of monocytes in the defense mechanism of the organism is discussed.

Adult↗