M-MuLV-induced leukemogenesis: Integration and structure of recombinant proviruses in tumors

M-MuLV-specific DNA probes were used to establish the state of integration and amplification of recombinant proviral sequences in Moloney virus-induced tumors of Balb/Mo, Balb/c and 129 mice. The somatically acquired viral sequences contain both authentic M-MuLV genomes and recombinants of M-MuLV with endogenous viral sequences. All reintegrated genomes carry long terminal repeat (LTR) sequences at both termini of their genome. In the preleukemic stage a large population of cells exhibiting a random distribution of reintegrated M-MuLV genomes are seen, but during outgrowth of the tumor, selection of cells occurs leaving one or a few clonal descendants in the outgrown tumor. In this latter stage recombinant genomes can be detected. Although these recombinants constitute a heterogeneous group of proviruses, characteristic molecular markers are conserved among many individual proviral recombinants, lending credence to the notion that a certain recombinant structure is a prerequisite for the onset of neoplasia. The structure of these recombinants shows close structural similarities to the previously described mink cell focus-inducing (MCF)-type viruses.     

The role of challenging incentives in feedback-assisted heart rate reduction for coronary-prone adult males

Three experiments were performed to study the influence of challenging incentives on feedback-assisted heart rate reduction for coronary-prone (Type A) and non-coronary-prone (Type B) males. In the first experiment, when subjects were given a competitive instructional set, Type As were significantly more successful relative to Type Bs in reducing their heart rate; with a noncompetitive set, Type Bs were significantly more successful than were Type As. In the second experiment, when told that heart rate reduction was a scarce ability, Type As reduced heart rate significantly better than did Type Bs; when told that heart rate reduction was a common ability, Type Bs achieved significantly greater heart rate reduction than did Type As. In the third experiment, when heart rate reduction was described as being instrumental to time-urgency (i.e., getting more done in less time), Type As reduced heart rate significantly bettern than did Type Bs; when heart rate reduction was described as being instrumental to relaxation, Type Bs were significantly better able to reduce heart rate. In all three studies, the incentives had no effect on heart rate when feedback was not provided. The results are discussed as support for the notion that Type A behavioral pattern characteristics can be exploited to reduce Type A symptoms. Implications for how coronary-prone individuals may be challenged to modify symptoms within the clinical setting are discussed.     

Trace feature map: a model of episodic associative memory

An approach to episodic associative memory is presented, which has several desirable properties as a human memory model. The design is based on topological feature map representation of data. An ordinary feature map is a classifier, mapping an input vector onto a topologically meaningful location on the map. A trace feature map, in addition, creates a memory trace on that location. The traces can be stored episodically in a single presentation, and retrieved with a partial cue. Nearby traces overlap, which results in plausible memory interference behavior. Performance degrades gracefully as the memory is overloaded. More recent traces are easier to recall as are traces that are unique in the memory.This research was supported in part by an ITA Foundation grant and by fellowships from the Academy of Finland, the Emil Aaltonen Foundation and the Foundation for the Advancement of Technology (Finland) when the author was at UCLA     

Diethyl phthalate, a chemotactic factor secreted by Helicobacter pylori.

The structure of a small-molecule, non-peptide chemotactic factor has been determined from activity purified to apparent homogeneity from Helicobacter pylori supernatants. H. pylori was grown in brucella broth media until one liter of solution had 0.9 absorbance units. The culture was centrifuged, and the bacteria re-suspended in physiological saline and incubated at 37 degrees C for 4 h. A monocyte migration bioassay revealed the presence of a single active chemotactic factor in the supernatant from this incubation. The chemotactic factor was concentrated by solid phase chromatography and purified by reverse phase high pressure liquid chromatography. The factor was shown to be indistinguishable from diethyl phthalate (DEP) on the basis of multiple criteria including nuclear magnetic resonance spectroscopy, electron impact mass spectroscopy, UV visible absorption spectrometry, GC and high pressure liquid chromatography retention times, and chemotactic activity toward monocytes. Control experiments with incubated culture media without detectable bacteria did not yield detectable DEP, suggesting it is bacterially derived. It is not known if the bacteria produce diethyl phthalate de novo or if it is a metabolic product of a precursor molecule present in culture media. DEP produced by H. pylori in addition to DEP present in man-made products may contribute to the high levels of DEP metabolites observed in human urine. DEP represents a new class of chemotactic factor.     

Obtaining a High Percentage of Explants with Negative Serological Reactions against viruses by Combining Potato Meristem Culture with Antiphytoviral Chemotherapy

A high percentage of plantlets, in which PVX, PVM, and PVS were no longer detectable by precipitin tests was obtained from 100% virus-infected stocks of the potato varieties Rosa and Priobskij rannija by combining meristem (tip) culture with antiphytoviral chemotherapy. When 2,4 - dioxohexahydro 1,3,5-triazinc (DHT) was added to the nutrient media, no virus was detectable serologically in 72% of the corresponding explants of the variety Rosa and in 66% of that of the variety Priobskij rannija, respectively. Contrary to this, all untreated control explants proved virusinfected. Treatment with 2-thiouracil resulted in 46.6%, with cyanoguanidine in 28.6% of plantlets, in which no virus was detectable serologically.     

Monoclonal antibodies to the hydrogenase ofThiocapsa roseopersicina

Monoclonal antibodies were produced to electrophoretically pure hydrogenase fromThiocapsa roseopersicina. Protein immunoelectroblotting was used to identify the hydrogenase-specific antibodies. Among the 18 monoclonal antibodies selected by enzyme immunoassay, three were found to react with highly immunogenic trace contaminating proteins. One cell line produced antibody that inhibitied hydrogenase activity. This was the first specific inhibitor of the hydrogenase function. The results suggest that monoclonal antibodies could provide valuable new informations about the enzyme structure as well.