The function of adenosylcobalamin in the mechanism of ribonucleoside triphosphate reductase from Lactobacillus leichmannii

BACKGROUND: Tumour necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine found in abundance in diseased intestine. AIMS: The T cell production of TNF-alpha and the impact of this cytokine on intestinal T cell proliferation, migration, and cytotoxicity were studied. METHODS: Intestinal lymphocytes from normal jejunum were used. TNF-alpha production in culture supernates was measured by enzyme linked immunosorbent assay (ELISA). Lymphocyte proliferation was measured using 3H thymidine uptake; migration, using transwell chambers; and cytotoxicity of HT-29 colon cancer cells, using the chromium-51 release assay. RESULTS: TNF-alpha was produced mainly by the CD8+ T cells in the intraepithelial lymphocytes (IEL) and the CD4+ T cells in the lamina propria lymphocytes in response to CD2 stimulation: 478 (94) and 782 (136) pg/ml, respectively. TNF-alpha (1 ng/ml or greater) augmented proliferation of IEL in response to interleukin 2 (IL-2), IL-7, or antibody to CD3 due to increased activation that did not involve IL-2 production or receptor generation. Conversely, antibody to TNF-alpha reduced IEL proliferation in response to IL-2 or IL-7. TNF-alpha also induced calcium mobilisation and chemokinesis (by 2.8 (0.5) fold over spontaneous migration). TNF-alpha had no effect on lymphokine activated killer cell activity. CONCLUSIONS: TNF-alpha increases the proliferation and migration of IEL, which may expand their number in the epithelium.     

Quantal release at visualized terminals of a crayfish motor axon: intraterminal and regional differences

Synaptic transmission was measured at visualized terminal varicosities of the motor axon providing the sole excitatory innervation of the "opener" muscle in walking legs of crayfish (Procambarus clarkii Girard). Two questions were addressed: 1) How uniform is quantal emission at different locations along terminals innervating a single muscle fiber, and 2) can differences in quantal emission account for the different excitatory postsynaptic potential (EPSP) amplitudes generated by terminals localized in defined regions of the muscle? Extracellular "macropatch" electrodes were placed over individual varicosities, viewed after brief exposure to a fluorescent dye, and synaptic currents were recorded to determine quantal content of transmission. Along terminals supplying a single muscle fiber, nonuniform release was found: Varicosities closer to the point of origin of the terminal branch released more transmitter than those located more distally. Quantal content was higher for varicosities of the muscle's proximal region (where large EPSPs occur) than for varicosities of the central region (where small EPSPs occur). The probability of transmitter release per synapse is estimated to be greater for the proximal varicosities. At low frequencies of stimulation, quantal content per muscle fiber is two to four times larger in the proximal region. Taken in conjunction with a twofold higher mean input resistance for the proximal muscle fibers, the difference in quantal content can account for a four- to eightfold difference in EPSP amplitude. The observed mean EPSP amplitude is at least eight times larger in the proximal region. We discuss factors contributing to differences in EPSP amplitudes.     

The formation and evolution of the Society of Nuclear Medicine

The Society of Nuclear Medicine was created and constructed by persons from many branches of medicine and the physical sciences, but it originated mostly in the mind of a chemist-physicist-engineer named Norman "Jeff" Holter. Because most medical organizations seemed to care little about the use of radioactive materials for medical purposes, Holter believed a new organization was necessary for their promotion. From its origin in 1954 as the Pacific Northwest Society of Nuclear Medicine, The Society of Nuclear Medicine became a national, multidisciplinary organization in 1956. Rapidly gathering strength with an expanding membership, it employed an administrator in 1959. With this administrator and a dedicated volunteer editor, publication of the Journal of Nuclear Medicine began. Over the next several years the Society evolved into an active force in the development of the application of radioactivity to medical applications. It generated significant internal initiatives and participated in the generation of several important external institutions. The Society of Nuclear Medicine developed a tradition of annual meetings with strong educational programs for all members. By nurturing and embracing the Technologist Section, the Society became a robust and representative organization for all who serve nuclear medicine. From these beginnings came the vigorous Society of Nuclear Medicine of today. Jeff Holter (1914-1983) would be justifiably proud.     

Interaction between radiation and drug damage in mammalian cells. II. The effect of actinomycin-D on the repair of the sublethal radiation damage in plateau phase cells

The effect of actinomycin-D (AMD) on radiation damage repair was studied in plateau phase V79 Chinese hamster cells. Sublethal radiation damage repair, as demonstrated by survival fluctuations following two x-ray exposures separted by time, was observed in our plateau phase cells. Plateau phase cells exposed to 0.01-0.04 mug/ml AMD (a nontoxic regimen to 8 hours) between x-ray exposures were less able to repair sublethal damage. If plateau phase cells were plated at low dilutions into fresh medium (conditions for resuming exponential growth) immediately after the first x-ray dose, and exposed to 0.01--0.04 mug/ml AMD until the second dose, inhibition of sublethal damage repair and additional cell killing were observed particularly at 0.04 mug/ml AMD. It is suggested that radiation-drug damage interactions should be studied in plateau phase cells and in cells resuming exponential growth after plateau phase (possibly analogous to "recruitment"), as well as in exponential phase cultures.     

Effects of hypothalamic temperature changes on the sweat rate in Macaca mulatta

The concept of cardiac reconditioning centers for the prevention and rehabilitation of coronary patients has been tremendously successful in Germany over the past 20 years. At least 40 such centers are located throughout the country. Physicians, nurses, and physical therapists work closely together in the various facets of the rehabilitation process. The financial backing for these facilities is primarily through governmental and regional insurance companies, whose officials are apparently convinced that in the long run supporting preventive measures is financially sound. Objective data supporting their convictions come from studies such as that of Brusis, who showed that such as that of 1,500 employees was diminished by nearly 70 percent during a two-year period after cardiac reconditioning, as compared to a similar time period before the rehabilitation experience. Subjective benefits, which are extremely difficult to quantitate in meaningful terms, were nonetheless expressed by nearly all the patients with whom I conversed. Perhaps they have experienced the same feelings that Mark Twain did when he observed that "all frets and worries and chafings sank to sleep in the presence of the benignant serenity of the Alps; the Great Spirit of the Mountains breathed his own peace upon their hurt minds and sore hearts and healed them."     

The emotional aftermath of adoption

Adopted children are emotionally vulnerable. Adoptive parents must cope with more complex problems than biologic parents. The family physician can provide valuable counseling. Preadoption counseling focuses on motivation and ambivalence. After adoption, however, serious, sometimes predictable, issues arise, such as: how and when to tell the child he is adopted; the child's search for knowledge; the problem of subsequent divorce; the birth of a natural sibling, and the involvement of other family members. New concepts include "open adoption" and "single parent adoption."