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Biomedical subjects

S Harris

Publications and source records attributed to S Harris.

At least 379 records · Page 21Linked to original sources
PubMed1975

Shifts from IgG-2 class to IgG-1 class in CBA and C3H anti-BALB/c antibody.

With use of a recently developed method for determining relative levels of IgG-1 and IgG-2 class antibodies of a given specificity within an unfractionated serum, it has been possible to examine anti-BALB/c antibodies in the early and late part of an immunization with allogeneic spleen cells. At about 6 days after primary immunization of CBA or C3H mice with BALB/c spleen cells, suppressive antibodies can be measured in the sera of the animals. About half of these are attributable to IgM class, and this contribution decreases to zero by the 12th day. The remaining suppressive antibodies are of IgG-2 class and these increase in concentration until day 8 or 12, or begin to decline between day 8 and day 12. Anti-BALB/c antibodies of IgG-1 class have not yet appeared on day 6, but thereafter appear and increase in concentration. Thus, antibodies of IgG-1 class begin to appear after those of the IgG-2 class and may still be increasing after the IgG-2 class has stopped to increase in concentration, antibody of IgG-1 class is continuing to increase and may even continue to increase after IgF-2 class antibody has begun to decrease in concentration. Thus, the synthesis of IgG-1 class antibody begins later and continues later than that of IgG-2 class. The implications of this sequence for our data on various effects of anti-H-2 antibodies on retention of skin allografts are discussed.

Animals↗
PubMed1973

Circadian rhythms in neurospora: spatial differences in pyridine nucleotide levels.

A growing colony of a mutant strain of Neurospora crassa had two morphologically distinct areas which were formed as a result of a rhythmic spore-forming (conidiation) process. The total pyridine nucleotide content of these two areas was the same, but the levels of NADH, NADPH, and NADP were lower in the conidiating area, while the NAD level was higher. These biochemical differences in the adjacent areas of a single colony were only found in newly formed areas, and were not a permanent record. It is not known whether these pyridine nucleotide changes are a result of the conidiation process, or whether they are tied more directly to some underlying metabolic oscillation. However, it is speculated that the changes in the levels of these key coenzymes could have far-reaching effects on many areas of metabolism.

Circadian Rhythm↗
PubMed1972

Studies on antibody-producing cells. IV. Ultrastructue of plaque-forming cells of rabbit lymph.

Efferent lymph of the popliteal lymph nodes of rabbits was collected 4 days after a single footpad injection of SRBC. Thin-layer agar plating was done to isolate plaque-forming cells of the lymph for electron microscope examination, and the numbers of plaque-forming cells (PFC) in cells from the lymph and lymph nodes were determined. Of 71 PFC of lymph isolated and examined, 93% were lymphocytes, most of them with signs of substantial levels of physiologic activity. The cytoplasm showed an abundance of free ribosomes and many finger-like projections. The endoplasmic reticulum (ER) was barely detectable in most of the active lymphocytic PFC, and in some, a few short narrow channels of ER could be seen. Approximately one-fifth of the lymphocytic PFC presented an appearance of senescence, with signs of degeneration: rounded cells, with amorphous nuclear chromatin, and very few microvilli. The remaining 7% of the PFC of the lymph showed an unusual combination of features: small round cells with a narrow ring of cytoplasm which, however, contained well-organized channels of ER. Such cells had been found only among PFC of peripheral blood of the rabbit. The number of PFC per million cells was higher in the lymph than in the suspensions of lymph node cells. In both the contralateral lymph node and its efferent lymph, the number of PFC was less than 1% that of the injected side.

Animals↗
PubMed1972

Preparation of dialyzable histocompatibility antigen from BALB-c mice (cell-membrane fragments-proteolytic digestion-detergent solubilization).

Histocompatibility antigens solubilized from cell-membrane fragments of BALB/c mouse spleen and liver, by Triton X-100 and butyl alcohol, were subjected to digestion by proteolytic enzymes in an effort to obtain smaller molecular species that retained antigenic activity. Digestion with both trypsin and papain yielded two antigens of smaller molecular weights that retained the specificity of BALB/c histocompatibility antigen, as determined by the inhibition of allogeneic antibodies, agglutination of BALB/c erythrocytes, adsorption-hemagglutination versus the soluble histocompatibility antigen, and suppression of the ability of BALB/c spleen cells to produce hemolytic plaques to sheep erythrocytes. The two active products of trypsin digestion were, respectively, excluded by Sephadex G-50 but not by G-75, and excluded by G-25 but not by G-50. Papain digestion yielded one active antigen that was excluded by G-25 but not by G-50, and a smaller antigen that was excluded by G-10 but not by G-15 and, as determined by gel filtration, has a molecular weight slightly lower than vitamin B(12).

Alcohols↗
PubMed1971

Studies on antibody-producing cells. 3. Identification of young plaque-forming cells by thymidine- 3 H labeling.

Mice injected with sheep RBC and then, 4 days later with thymidine-(3)H, were sacrificed on the day of thymidine-(3)H injection or 1 or 2 days later. Hemolytic antibody plaque preparations were made of cells from the draining lymph nodes by a thin-plating procedure permitting collection of isolated PFC for electron microscopic examination and radioautography. Of cells obtained on the day of thymidine-(3)H injections, 65% of the labeled PFC were in the lymphocytic category, in comparison with 13% found previously in the entire population of such cells. The remaining 35% were plasmablasts in early stages of differentiation. Cells obtained 1 day after the thymidine-(3)H injections showed a shift to a majority of labeled cells in the plasmacytic category. Also, the plasmablasts were substantially more differentiated than those of the previous day, and some mature plasma cells were now seen. The labeled PFC obtained on day 2 gave no indication of further differentiation. Cells of rabbit lymph nodes labeled in vitro with thymidine-(3)H showed a range of labeled PFC. The majority were in the plasmacytic category, including some mature plasma cells. The data from the experiments with in vivo labeling suggest a direct differentiation from antibody-synthesizing lymphocytes to plasma cells. Further, the in vivo experiments indicated that differentiation from nascent lymphocyte to plasma cell could be essentially completed within 1 day.

Animals↗
PubMed1971

Studies on antibody-producing cells. II. Appearance of 3 H-thymidine-labeled rosette-forming cells.

A study of the kinetics of antibody-producing cells has been carried out by the use of rosette formation for detection of individual antibody-producing cells, and labeling with tritiated thymidine, in cells obtained from mouse spleens at intervals after injection of SRBC. Following a primary injection of the antigen, the number of RFC per million cells was found to increase to a peak at 5 days, then, after a decrease, to a second peak at about the 10th day. The curve of tritium labeling of RFC was also biphasic, with peaks on the 3rd and 7th day. The second increase in rosette-forming cells could be shown to involve, especially between the 7th and 9th day, a second increase in lymphoid cell RFC and, among these, 7S antibody-producing cells. When the population examined was restricted to large lymphocytes, two peaks of RFC per million cells and two peaks of labeling were again found. In this case, however, the peaks of RFC and of labeling were reached on the same day in each instance, rather than with the 2 day difference found in the entire spleen cell suspension or the entire lymphoid cell population. Electron microscopic examination of labeled rosette-forming cells showed these to be largely lymphocytes, but to include rather well differentiated plasmablasts as well. No macrophages were found among labeled RFC in the primary response. A substantial number of labeled lymphocytes were found in close contiguity with rosette-forming macrophages. The percentage of labeling in such lymphocytes was as high, on the respective days, as the percentage of labeled cells among the RFC of the entire suspension.

Animals↗