Monoclonal antibody uptake in B-cell lymphomas: Experimental studies in nude mouse xenografts

Accumulation of radiolabelled monoclonal antibodies (mAb) in human B-lymphoma xenografts was found to result in two distinct patterns. The basic elements leading to these patterns were elucidated by autoradiographic and immunohistological analysis applied to the nude mouse xenografts BJAB and OCI.LY1. With BJAB, accumulation occurred exclusively in peripheral cell layers of the lymphoma nodule, while central areas were not accessible irrespective of mAb dose. This feature was the consequence of an inefficient transport across intratumoral vessels together with peripheral mAb supply through a subcapsular pseudosinus. With OCI.LY1, intratumoral vessels showed generalized leakiness. Furthermore, interstitial transport was operative to a fair extent, such that in early images multiple sites of mAb extravasation were obvious, which coalesced during the course of prolonged uptake. The pattern of peripheral mAb uptake resulted in a low overall tumour uptake, while multifocal uptake yielded substantial accumulation values.     

An estimate of unique DNA sequence heterozygosity in the human genome

Summary Patients with recessive X-linked ichthyosis Patients with recessive X-linked ichthyosis (RXLI), one hereditary form of scaly skin, lack activity of the enzyme steroid sulfatase in all tissues studied. To investigate the molecular defect underlying the lack of enzyme activity, we prepared antisera against normal enzyme by injecting normal placental microsomal suspensions or partially purified steroid sulfatase into rabbits. Antibody activity was assessed by immunoprecipitation of detergent solubilized steroid sulfatase. In addition, we prepared rabbit antisera against RXLI placental microsomal suspensions. To detect immunologically cross-reactive material in patients' placentas, extracts were studied by immunoblot techniques and by competition with normal enzyme for antibody binding. Patients' extracts did not contain immunoreactive material co-migrating on electrophoresis with purified enzyme nor did they inhibit immunoprecipitation of normal enzyme. Sera from rabbits immunized with RXLI placental microsomes contain no antibodies to normal steroid sulfatase, as judged by their failure to immunoprecipitate normal enzyme or to react with normal steroid sulfatase on immunoblot. Thus the mutation in RXLI appears to reduce steroid sulfatase enzyme protein as well as enzyme activity. Portions of this material have appeared in abstract form in Clinical Research 31:564A, 1983 and 32:138A, 1984     

Ultrastructure of the Y-organ of Astacus astacus (L.) (Crustacea) in relation to the moult cycle

Summary The electron microscopical investigation of Y-organs of Astacus astacus revealed that during intermoult (stage C) the cytoplasm is poorly developed and that it increases at premoult (stage D). It then shows the typical signs of steroid production, namely agranular endoplasmic reticulum and mitochondria of the tubular type. Furthermore, a larger type of mitochondria with a regular pattern of internal structure is described.Supported by Sächsische Akademie der Wissenschaften zu LeipzigWe are grateful for technical assistance to Mrs. B. Cosack und Mrs. A. Schmidt     

Methane-Carbon Flow into the Benthic Food Web at Cold Seeps – A Case Study from the Costa Rica Subduction Zone

Cold seep ecosystems can support enormous biomasses of free-living and symbiotic chemoautotrophic organisms that get their energy from the oxidation of methane or sulfide. Most of this biomass derives from animals that are associated with bacterial symbionts, which are able to metabolize the chemical resources provided by the seeping fluids. Often these systems also harbor dense accumulations of non-symbiotic megafauna, which can be relevant in exporting chemosynthetically fixed carbon from seeps to the surrounding deep sea. Here we investigated the carbon sources of lithodid crabs (Paralomis sp.) feeding on thiotrophic bacterial mats at an active mud volcano at the Costa Rica subduction zone. To evaluate the dietary carbon source of the crabs, we compared the microbial community in stomach contents with surface sediments covered by microbial mats. The stomach content analyses revealed a dominance of epsilonproteobacterial 16S rRNA gene sequences related to the free-living and epibiotic sulfur oxidiser Sulfurovum sp. We also found Sulfurovum sp. as well as members of the genera Arcobacter and Sulfurimonas in mat-covered surface sediments where Epsilonproteobacteria were highly abundant constituting 10% of total cells. Furthermore, we detected substantial amounts of bacterial fatty acids such as i-C15∶0 and C17∶1ω6c with stable carbon isotope compositions as low as −53‰ in the stomach and muscle tissue. These results indicate that the white microbial mats at Mound 12 are comprised of Epsilonproteobacteria and that microbial mat-derived carbon provides an important contribution to the crab''s nutrition. In addition, our lipid analyses also suggest that the crabs feed on other ¹³C-depleted organic matter sources, possibly symbiotic megafauna as well as on photosynthetic carbon sources such as sedimentary detritus.     

The adhering junctions of valvular interstitial cells: molecular composition in fetal and adult hearts and the comings and goings of plakophilin-2 in situ, in cell culture and upon re-association with scaffolds

The interstitial cells of cardiac valves represent one of the most frequent cell types in the mammalian heart. In order to provide a cell and molecular biological basis for the growth of isolated valvular interstitial cells (VICs) in cell culture and for the use in re-implantation surgery we have examined VICs in situ and in culture, in fetal, postnatal and adult hearts, in re-associations with scaffolds of extracellular matrix (ECM) material and decellularized heart valves. In all four mammalian species examined (human, bovine, porcine and ovine), the typical mesenchymal-type cell-cell adherens junctions (AJs) connecting VICs appear as normal N-cadherin based puncta adhaerentia. Their molecular ensemble, however, changes under various growth conditions insofar as plakophilin-2 (Pkp2), known as a major cytoplasmic plaque component of epithelial desmosomes, is recruited to and integrated in the plaques of VIC-AJs as a major component under growth conditions characterized by enhanced proliferation, i.e., in fetal heart valves and in cell cultures. Upon re-seeding onto decellularized heart valves or in stages of growth in association with artificial scaffolds, Pkp2 is - for the most part - lost from the AJs. As Pkp2 has recently also been detected in AJs of cardiac myxomata and diverse other mesenchymal tumors, the demonstrated return to the normal Pkp2-negative state upon re-association with ECM scaffolds and decellularized heart valves may now provide a safe basis for the use of cultured VICs in valve replacement surgery. Even more surprising, this type of transient acquisition of Pkp2 has also been observed in distinct groups of endothelial cells of the endocardium, where it seems to correspond to the cell type ready for endothelial-mesenchymal transition (EMT).     

Inflammatory macrophages induce Nrf2 transcription factor-dependent proteasome activity in colonic NCM460 cells and thereby confer anti-apoptotic protection

Adaptation of epithelial cells to persistent oxidative stress plays an important role in inflammation-associated carcinogenesis. This adaptation process involves activation of Nrf2 (nuclear factor-E2-related factor-2), which has been recently shown to contribute to carcinogenesis through the induction of proteasomal gene expression and proteasome activity. To verify this possible link between inflammation, oxidative stress, and Nrf2-dependent proteasome activation, we explored the impact of inflammatory (M1) macrophages on the human colon epithelial cell line NCM460. Transwell cocultures with macrophages differentiated from granulocyte monocyte-colony-stimulating factor-treated monocytes led to an increased activity of Nrf2 in NCM460 cells along with an elevated proteasome activity. This higher proteasome activity resulted from Nrf2-dependent induction of proteasomal gene expression, as shown for the 19 and 20 S subunit proteins S5a and α5, respectively. These effects of macrophage coculture were preceded by an increase of reactive oxygen species in cocultured NCM460 cells and could be blocked by catalase or by the reactive oxygen species scavenger Tiron, whereas transient treatment of NCM460 cells with H(2)O(2) similarly led to Nrf2-dependent proteasome activation. Through the Nrf2-dependent increase of proteasomal gene expression and proteasome activity, the sensitivity of NCM460 cells to tumor necrosis factor-related apoptosis-inducing ligand- or irinotecan-induced apoptosis declined. These findings indicate that inflammatory conditions such as the presence of M1 macrophages and the resulting oxidative stress are involved in the Nrf2-dependent gain of proteasome activity in epithelial cells, e.g. colonocytes, giving rise of greater resistance to apoptosis. This mechanism might contribute to inflammation-associated carcinogenesis, e.g. of the colon.     

Chronic instrumentation and longterm investigation in the fetal and maternal baboon: tether system, conditioning procedures and surgical techniques

A tether system, conditioning procedures and surgical techniques were designed to maintain chronic catheters and electrodes in the pregnant baboon and her fetus. The tether system was comprised of a lightweight metal backpack containing catheters and electrodes, couplers, pressure transducers and electrical cabling. The backpack was held snugly in place by shoulder and body straps. A flexible metal tether connected the pack to a ball bearing assembly mounted on the top of the animal's home cage. Attached to the assembly were two infusion pumps, fluid reservoir and slip ring electrical connector. The entire system rotated freely with the movements of the animal; thus, the instrumentation and connectors were secure while access was maintained for continuous physiologic recording and intravascular infusion or intermittent blood sampling with minimal physical restraint. Animals were conditioned to accept the system prior to pregnancy and animals who demonstrated tolerance were bred. An initial group of 10 pregnant animals were sham tethered during pregnancy at 102 +/- 7 days with term gestation estimated at 180 days. Surgical procedures were done at 136 +/- 4 days with placement of catheters in the maternal femoral artery and vein, fetal carotid artery jugular vein and trachea, amniotic fluid cavity, and electrodes for fetal electrocardiogram and electroencephalogram. The mean fetal survival time was 9.3 (range 0 to 29) days. The major complications which led to early delivery were placental abruption and rupture of amniotic membranes. With ultrasonic localization of the placenta and determination of fetal position before surgery, these complications may be avoided.(ABSTRACT TRUNCATED AT 250 WORDS)