Cell differentiation features in embryos resulting from interphylum nuclear transplantation: echinoderm nucleus to ascidian zygote cytoplasm

When an echinoderm nucleus was transplanted into an ascidian zygote cytoplast there was developmental cooperation at the cellular level between nucleus and cytoplasm of these normally nonhybridizable species. A blastula stage nucleus from the sand dollar Echinarachnius parma was injected into an activated but nonnucleate egg fragment of the ascidian Ciona intestinalis. During culture, some of the "hybrid" embryos displayed ultrastructural evidence of cellular differentiation. Two recognizable features were (1) extracellular matrix components, and (2) neural cell characteristics, including elaboration of associated cilia. Nonnucleate zygote fragments alone, and such fragments injected with seawater or punctured by glass needle, did not develop organized subcellular structures. Morphologic expressions resulting from nuclear transplantations between these two phyla (Echinodermata and Chordata) seemingly indicate functional interactions at a gene regulatory level. Creation of such nuclear-cytoplasmic hybrids suggests thereby a means of exploring the nature of the egg cytoplasmic agents in ascidian embryos that appear to determine gene expression related to histospecific differentiation products.     

Differentiation of histospecific ultrastructural features in cells of cleavage-arrested early ascidian embryos

Summary Ultrastructural features of histospecific differentiation were found in early cleavage stage ascidian embryos treated with cytochalasin B and held thereby in cleavagearrest until hatching time. Markers characteristic of tissue differentiation during normal embryonic and larval stages ofCiona intestinalis were expressed in muscle and two brain cell lineages of cleavage-arrested whole embryos and in epidermal and notochordal cell lineages of cleavage-arrested partial embryos. These features were muscle myofilaments and myofibrils, melanosomes of the brain pigment cells, cilium-derived structures present in a proprioceptive brain cell, extracellular test material of epidermal cell origin, and the sheath filaments, membrane leaflets, and vacuolar colloid associated with notochord cells. All of these ultrastructural markers of differentiation were blocked in their development by treatment of gastrula stage embryos with actinomycin D, an inhibitor of RNA synthesis, and presumably result from the expression of new gene activity. At the time of cleavage-arrest the five cell lineages studies still contained two or more unsegregated lineage pathways. Subsequent developmental autonomy within the lineages is consistent with the hypothesis of segregation during early development of functionally independent gene regulatory factors.     

Effects of intermittent 5-fluorouracil and adriamycin on various immune parameters in carcinoma patients with reference to the tumour load

Summary Adriamycin and 5-fluorouracil were used to treat nineteen patients with metastatic carcinoma. There were different effects upon in vitro immune reactivity in those patients who responded, as compared to those who did not respond to this chemotherapy. Assays used to measure immune reactivity included total lymphocyte count, E and EAC rosettes, direct cellular cytotoxicity, antibody-dependent cellular cytotoxicity and PHA induced cytotoxicity against a Change cell target system. Both patient groups were immuno-depressed prior to treatment. Successful therapy reduced this depression in non-T cell cytotoxicity and in E rosette number. In contrast, the non-responding patients exhibited further depression of non-T function as measured by direct cellular cytotoxicity and antibody-dependent cellular cytotoxicity.     

Comparison of combined and single-agent chemotherapy in non-Hodgkin's lymphoma of favourable histological type.

Sixty-six untreated patients with advanced non-Hodgkin''s lymphoma of favourable histological type were allocated alternately to initial treatment with cyclophosphamide, vincristine, and prednisolone or with chlorambucil. The complete remission rate was higher in the group receiving combination chemotherapy, but the overall response rate was the same for both groups. The mean duration of complete remission was the same as that of good partial remission, and was the same for both treatments. The duration of remission was influenced by histological type and extent of disease at presentation, but not age. Those who responded to the initial treatment (whether with complete or with good partial remission) survived significantly longer than did non-responders. It is concluded that neither treatment is satisfactory and that new treatment programmes are needed for patients with a favourable prognosis, especially young patients with extensive disease.     

Molecular cloning of a highly leukemogenic, ecotropic retrovirus from an AKR mouse.

SL3-3 is a leukemogenic, ecotropic retrovirus produced by a T-cell line derived from a spontaneous lymphoma of an AKR mouse. We have isolated a molecular clone of its DNA provirus from infected NIH 3T3 fibroblasts. Cloned proviral DNA produced infectious virus upon transfection onto NIH 3T3 cells. Virus derived by transfection induced lymphomas at high frequency in AKR/J, C3H(f)/Bi, CBA/J, and NFS/N mice. Heteroduplex and RNase T1 fingerprinting analyses showed that the genomes of SL3-3 and the non-leukemogenic virus, Akv, contain no major substitutions relative to one another and differ by only a few base changes. These results unambiguously show that SL3-3 is a highly leukemogenic virus and that major rearrangements of the genome relative to Akv are not required for virulence.     

Nucleotide Sequence of the Akv env Gene

The sequence of 2,191 nucleotides encoding the env gene of murine retrovirus Akv was determined by using a molecular clone of the Akv provirus. Deduction of the encoded amino acid sequence showed that a single open reading frame encodes a 638-amino acid precursor to gp70 and p15E. In addition, there is a typical leader sequence preceding the amino terminus of gp70. The locations of potential glycosylation sites and other structural features indicate that the entire gp70 molecule and most of p15E are located on the outer side of the membrane. Internal cleavage of the env precursor to generate gp70 and p15E occurs immediately adjacent to several basic amino acids at the carboxyl terminus of gp70. This cleavage generates a region of 42 uncharged, relatively hydrophobic amino acids at the amino terminus of p15E, which is located in a position analogous to the hydrophobic membrane fusion sequence of influenza virus hemagglutinin. The mature polypeptides are predicted to associate with the membrane via a region of 30 uncharged, mostly hydrophobic amino acids located near the carboxyl terminus of p15E. Distal to this membrane association region is a sequence of 35 amino acids at the carboxyl terminus of the env precursor, which is predicted to be located on the inner side of the membrane. By analogy to Moloney murine leukemia virus, a proteolytic cleavage in this region removes the terminal 19 amino acids, thus generating the carboxyl terminus of p15E. This leaves 15 amino acids at the carboxyl terminus of p15E on the inner side of the membrane in a position to interact with virion cores during budding. The precise location and order of the large RNase T(1)-resistant oligonucleotides in the env region were determined and compared with those from several leukemogenic viruses of AKR origin. This permitted a determination of how the differences in the leukemogenic viruses affect the primary structure of the env gene products.     

L-Asparaginase in Treatment of Acute Leukaemia and Lymphosarcoma

L-Asparaginase was used to treat 40 patients with acute leukaemia or lymphosarcoma. Fifteen with acute lymphoblastic leukaemia either untreated or in relapse after previous therapy were given “Squibb,” “Bayer,” or “Porton” L-asparaginase. Five of these patients had complete remission of their disease, and four had good partial remission. Eleven patients with acute myeloid leukaemia were treated for a short period with L-asparaginase alone. None of them went into remission though a pronounced fall in the numbers of circulating white cells was seen. Six patients with lymphosarcoma received L-asparaginase, two of them having good partial remissions.The toxic side-effects of the L-asparaginase from the three sources seemed to vary, and L-asparaginase from Erwinia carotovora appeared to be antigenically different from the enzyme produced by Escherichia coli.The way in which leukaemic cells become resistant to the action of the enzyme requires further investigation. To overcome this resistance asparaginase should be used in combination with other drugs in the treatment of acute leukaemia.     

Partial characterization of cyclic electron transport in intact chloroplasts

Turnover of the cyclic electron transfer chain around photosystem I in intact chloroplasts was induced by addition of sodium dithionite after poisoning with 3-(3,4-dichlorophenyl)-1,1-dimethylurea. A substantial permeability barrier to dithionite allowed redox poising to a level sufficiently negative to activate, but not overreduce, the cycle. Spectral changes could thus be studied without interference from photosystem II reactions. Illumination by repetitive single-turnover flashes showed the participation in the cycle of cytochromes f and b₅₆₃ with an apparent 1:1 stoichiometry. The rise of the flash-induced electrochromic bandshift (“P518”) showed a fast phase with rise time < 10 μs and a slow phase with rise time variable in the millisecond range. The slow phase had an amplitude equal to that of the fast phase and occurred only when electron transfer between cytochromes b₅₆₃ and f was uninhibited. A kinetic correlation was observed between the rise of the slow phase and the rereduction of cytochrome f, whereas cytochrome b₅₆₃ reoxidation was slower than both. Redox titrations of the appearance of the slow rise in the P518 response showed that it was only observed on repetitive flashes when a component of midpoint potential ～- ?55 mV (pH 8.1), n = 2, was reduced before the flash. A comparison is drawn between this protonmotive electron transfer cycle and that of the purple nonsulfur bacterium Rhodopseudomonas capsulata; possible arrangements of electron carriers in the photosystem I cycle are discussed, and a modified Q cycle is proposed to account for the properties observed.     

Meta-analysis of benzodiazepine use in the treatment of acute alcohol withdrawal

OBJECTIVE: To analyse the evidence for the efficacy and potential harmful effects of benzodiazepines compared with other therapies in the treatment of acute alcohol withdrawal. DATA SOURCES: MEDLINE and the Cochrane Controlled Trials Registry were searched for English-language articles published from 1966 to December 1997 that described randomized controlled trials (RCTs) of benzodiazepines in the treatment of acute alcohol withdrawal. Key words included "benzodiazepines" (exploded) and "randomized controlled trial." Bibliographies of relevant articles were reviewed for additional RCTs, and manufacturers of benzodiazepines were asked to submit additional RCT reports not in the literature. STUDY SELECTION: Articles were considered for the meta-analysis if they were RCTs involving patients experiencing acute alcohol withdrawal and comparing a benzodiazepine available in Canada with placebo or an active control drug. Of the original 23 trials identified, 11 met these criteria, representing a total of 1286 patients. DATA EXTRACTION: Data were extracted regarding the participants, the setting, details of the intervention, the outcomes (including adverse effects) and the methodologic quality of the studies. DATA SYNTHESIS: The meta-analysis of benefit (therapeutic success within 2 days) showed that benzodiazepines were superior to placebo (common odds ratio [OR] 3.28, 95% confidence interval [CI] 1.30-8.28). Data on comparisons between benzodiazepines and other drugs, including beta-blockers, carbamazepine and clonidine, could not be pooled, but none of the alternative drugs was found to be clearly more beneficial than the benzodiazepines. The meta-analysis of harm revealed no significant difference between benzodiazepines and alternative drugs in terms of adverse events (common OR 0.67, 95% CI 0.34-1.32) or dropout rates (common OR 0.68, 95% CI 0.47-0.97). INTERPRETATION: Benzodiazepines should remain the drugs of choice for the treatment of acute alcohol withdrawal.