Antigenic relationships among five reovirus-like (RVL) agents by complement fixation (CF) and development of new substitute CF antigens for the human RVL agent of infantile gastroenteritis.

The human reovirus-like (HRVL) agent, Nebraska calf diarrhea virus (NCDV), epizootic diarrhea of infant mice (EDIM) virus, simian agent (SA)-11, and the "O" (offal) agent were found to be similar, if not identical, in reciprocal complement fixation (CF) tests employing hyperimmune animal sera. In addition, in CF tests with paired sera from 35 diarrhea patients who shed the HRVL agent, 74% developed serologic evidence of infection with the HRVL antigen, 43% with NCDV, 51% with EDIM virus, 57% with SA-11, and 71% with the "O" agent. Thus, in addition to the NCDV, which had previously been described as a suitable substitute CF antigen for the HRVL agent, the SA-11, "O", and EDIM viruses may also be utilized as substitute antigens for the HRVL agent. However, the "O" agent appears to be the most efficient of the four substitute CF antigens and thus should be used preferentially when the HRVL agent is not available. The "O" agent was about as efficient as the HRVL agent and significantly more efficient than the NCDV for detecting seroresponses. The greatest efficiency for detecting infection with the HRVL agent resulted when sera were tested with both the HRVL and "O" agents as 31 (89%) of the patients developed serologic evidence of infection with one or both antigens. The finding of additional substitute CF antigens for the HRVL agent may have implications in the immunoprophylaxis against human disease.     

Amino acid transport in normal and glutathione-deficient sheep erythrocytes.

1. Uptake rates for 23 amino acids were measured for both normal (high-GSH) and GSH-deficient (low-GSH) erythrocytes from Finnish Landrace sheep. 2. Compared with high-GSH cells, low-GSH cells had a markedly diminished permeability to D-alanine, L-alanine, alpha-amino-n-butyrate, valine, cysteine, serine, threonine, asparagine, lysine and ornithine. Smaller differences were observed for glycine and proline, whereas uptake of the other amino acids was not significantly different in the two cell types.     

Dye Reduction Method for Estimating Bacterial Counts in Ground Beef

A dye reduction method was developed for estimating total aerobic and/or psychrotrophic bacterial counts in ground beef. The method is based on color changes in indicator disks placed on the meat surface.     

The number of globin gene sequences in "cytoplasmic" DNA fragments.

DNA was isolated from the cytoplasm of primary cultures of mouse foetal liver cells. The proportion of globin genes was determined by two methods of cDNA-DNA hybridisation in globin complementary DNA excess. The proportion was similar in ‘cytoplasmic’ DNA and nuclear DNA. This argues against an informational role for this class of ‘cytoplasmic’ DNA, which has all of the characteristics of nuclear DNA arising from nucleosomes derived from chromatin.     

Cell culture factors influencing in vitro expression of mouse mammary tumor virus

Summary Several cell culture factors were found to influence in vitro expression of mouse mammary tumor virus (MMTV) in the mouse adenocarcinoma cell line Mm5mt/c₁. Cells were propagated in a variety of commercially available cell culture media to which dexamethasone (DXM) was added as a stimulator of MMTV production. Culture seeding density, culture medium type, and glucose concentration each influenced MMTV production when expressed on a per cell basis. Maximum cell growth occurred in cultures grown in RPMI-1640 medium containing insulin. Those media which provided good cell growth were not necessarily optimal for virus expression. Addition of insulin did not stimulate MMTV synthesis although dexamethasone alone was stimulatory in all media used; however, maximum MMTV expression was obtained when dexamethasone and insulin were used in concert. Equivalent levels of MMTV-specific cell membrane antigen, MMTV-specific protein, and virus particles were produced at incubation temperatures of 32°, 34° or 37° C; however, higher levels of virus-related RNA-dependent DNA polymerase (RDDP) activity were recovered from cultures incubated at 32° and 34° C than at 37° C. Decreased levels of RDDP were attributed to enzyme thermolability at 37° C incubation. Research sponsored by the National Cancer Institute under Contract No. N01-CO-25423 with Litton Bionetics, Inc., and Contract No. N01-CP-33253 with the University of California.     

The partial replacement of the serum growth factor requirement of SV3T3 cells by lactalbumin hydrolyzate.

Lactalbumin hydrolyzate (LH), a commercially prepared, enzymatic digest of a milk protein fraction, can partially replace the serum requirement of SV3T3 cells. In a low, but obligatory, background of calf serum (0.15% v/v), LH carses a large increase in the final cell density (5-10 x over the control) while modestly steimulating the actual growth rate. Lactalbumin hydrolyzate does not contain survival activity for SV3T3 cells and does not affect the growth of 3T3 cells. Since even prolonged exposure to pH 4 or 2 results in complete abolishment of the growth-rate stimulatory capability without affecting the capacity to increase the final cell density, it is possible that the LH growth activity may consist of two dissociable components. All of LH growth activity is water soluble, autoclavable, and resists proteolytic treatment. On Sephadex G15 growth activity appears as a single peak at the void volume but on G25 it is retained beyond the void volume as a broad, skewed peak. The relevant molecular weight range lies between 1,500 and 4,000. The putative low pH resistant material is strongly adsorbed to Dowex 1 x 2 and can be displaced from the column by a reduction in the pH. A comparison of the properties of the LH factors with those of known growth promoting agents isolated from serum and various enzymatic digests indicates that these new factors do not correspond to any of these agents.     

Glycine-specific synapses in rat spinal cord. Identification by electron microscope autoradiography

Glycine, an inhibitory transmitter in spinal cord, is taken up into specific nerve terminals by means of a unique high-affinity uptake system. In this study, [3H]glycine was directly microinjected into rat ventral horn in vivo and electron microscope autoradiography used to localize the label in various anatomic compartments. Quantiative analysis showed that [3H]glycine labeled a high proportion of axosomatic and axodendritic synapses which presumably act to inhibit spinal motor neurons.     

Physiology and fine structure of sporangiospore germination in Piptocephalis unispora prior to infection

Germination of the sporangiospore of Piptocephalis unispora Benjamin, observed by means of light and electron microscopy, involved the formation of a new inner wall which became continous with the inner layer of the wall of the germ tube. The outer wall layer of the germ tube was continous with the original inner wall layer of the dormant spore. Preliminary details of appressorium structure were noted. Nutritional experiments indicated that sporangiospores required external sources of utilisable nitrogen and carbon compounds for maximal swelling and germ tube production. Limited development occurred when either nutrient was supplied singly. Comparison of germination of the asexual spore with that in other Mucorales, especially the Kickxellaceae, has been made, and the merosporangial status in P. unispora discussed.Non-Standard Abbreviations CH casein hydrolysate - Q spore quotient