Association of a 70-kDa tyrosine phosphoprotein with the CD16:ζ:γ complex expressed in human natural killer cells

The CD16: ζ: γ receptor complex allows natural killer (NK) cells to recognize and eliminate antibody-coated target cells. Whereas the ectodomain of CD16 is the receptor for Fcγ domains of immunoglobulins, disulfide-linked homo- and heterodimers composed of ζ and γ are required for the cell surface expression, and signal transduction properties of the complex. Engagement of CD16 activates the tyrosine kinase pathway, which induces the tyrosine phosphorylation of several substrates, including the ζ subunit and the phospholipase C γ-1 and γ-2 isoforms. Here we show that CD 16 stimulation of either peripheral blood NK cells, leukemic NK cells, or Jurkat transformants expressing a CD16:ζ:γ receptor complex, results in the tyrosine phosphorylation of a 70 kDa ζ-associated protein (pp70). Similarly, a 70-kDa ζ-associated phosphoprotein in T cells has been shown to be a tyrosine kinase (ZAP-70). Peptide mapping analysis indicates that the 70-kDa ζ-associated phosphoproteins from T cells and NK cells are structurally indistinguishable. We conclude that the CD16:ζ:γ complex may use a ZAP-70-related non-receptor tyrosine kinase, in the CD16 signaling cascade leading to NK cell activation.     

Ultrastructural alterations in caudate nucleus in aged cats

These studies provide information on the changes in the ultrastructure in the caudate nucleus of aged cats. The major findings was that there was a decrease in the density of synapses in caudate neuropil. This decrease occurred in animals after 3 years of age and remained relatively constant in older animals. In conjunction with this change a population of unusually long synapses also occurred. These larger synaptic appositions were associated with enlarged spine heads. The caudate also showed a number of qualitative ultrastructural alterations. Many neurons contained accumulations of lipofuscin or lipopigment granules in aged animals. These inclusions occurred in both soma and dendrites of neurons and all types of glial cells. A unique configuration of collapsed agranular cisterns also was observed in aged animals. The present results indicate that decreases in synaptic density may by one morphological event underlying functional alterations observed in caudate neurons in aged cats.     

Cytochemical characteristics of neurons in the trigeminal mesencephalic nucleus of hatchling chicks

The goal of the present study was to identify cytochemical markers characteristic of muscle afferents in hatchling chicks. To this end, we stained neurons in the trigeminal mesencephalic nucleus with a variety of markers that label subsets of neurons in avian dorsal root ganglia. We found that trigeminal mesencephalic neurons are surprisingly heterogeneous in their cytochemical make-up, expressing, to varying degrees, substance P, cholecystokinin, carbonic anhydrase, calbindin D-28k, parvalbumin, and S-100β. Calbindin D28k and S-100β appeared to be expressed equally in medial and lateral divisions of the trigeminal mesencephalic nucleus. In contrast, substance P- and cholecystokinin-immunoreactive neurons were more abundant in the medial division, whereas carbonic anhydrase activity and parvalbumin immunoreactivity were stronger in the lateral division. We were unable to detect met-enkephalin, neuropeptide Y, calcitonin gene-related peptide, vasoactive intestinal peptide, somatostatin, γ-aminobutyric acid, or tyrosine hydroxylase in the trigeminal mesencephalic nucleus. Moreover, these neurons did not appear to bind the lectin Dolichos biflorus agglutinin. The heterogeneity of expression of markers among trigeminal mesencephalic nucleus neurons, especially between neurons in the medial and lateral divisions, suggests that these neurons are functionally diverse.     

Cognitive rehabilitation in the elderly: overview and future directions.

This study provides an overview of the papers emanating from the experimental trial that evaluated a new cognitive rehabilitation program in older adults who were experiencing normal cognitive decline. The main features of the design are summarized, along with evidence that the training produced long-lasting improvement in memory performance, goal management, and psychosocial status. The benefits were attributed to several factors, including the program's emphasis on techniques that promoted efficient strategic processing. Limitations of the program and directions for future research are discussed.     

Cardiac atrophy in women following bed rest

Both chronic microgravity exposure and long‐duration bed rest induce cardiac atrophy, which leads to reduced standing stroke volume and orthostatic intolerance. However, despite the fact that women appear to be more susceptible to post‐spaceflight presyncope and orthostatic hypotension than male astronauts, most previous high‐resolution studies of cardiac morphology following microgravity have been performed only in men. Because female athletes have less physiological hypertrophy than male athletes, we reasoned that they also might have altered physiological cardiac atrophy after bed rest. Magnetic resonance imaging was performed in 24 healthy young women (32.1±4 years) to measure left ventricular (LV) and right ventricular (RV) mass, volumes, and morphology accurately before and after 60 days of 6° head‐down tilt (HDT) bed rest. Subjects were matched and then randomly assigned to sedentary bed rest (controls, n=8) or two treatment groups consisting of (1) exercise training using supine treadmill running within lower body negative pressure plus resistive training (n=8), or (2) protein (0.45 g/kg/day increase) plus branched‐chain amino acid (BCAA) (7.2 g/day) supplementation (n=8). After sedentary bed rest without nutritional supplementation, there were significant reductions in LV (96±26–77±25 mL; P=0.03) and RV volumes (104±33–86±25 mL; P=0.02), LV (2.2±0.2–2.0±0.2 g/kg; P=0.003) and RV masses (0.8±0.1–0.6±0.1 g/kg; P<0.001), and the length of the major axis of the LV (90±6–84±7 mm. P<0.001), similar to what has been observed previously in men (8.0%; Perhonen M.A., Franco F., Lane L.D., Buckey J.C., Blomqvist Zerwekh J.E., Peshock R.M., Weatherall P.T., Levine B.D. J Appl Physiol 2001: 91: 645–653). In contrast, there were no significant reductions in LV or RV volumes in the exercise‐trained group, and the length of the major axis was preserved. Moreover, there were significant increases in LV (1.9±0.4–2.3±0.3 g/kg; P<0.001) and RV masses (0.7±0.1–0.8±0.2 g/kg; P=0.002), as well as mean wall thickness (9±2–11±1 mm; P=0.02). The interaction between sedentary and exercise LV and RV masses was highly significant (P<0.0001). Protein and BCAA supplementation led to an intermediate phenotype with no change in LV or RV mass after bed rest, but there remained a significant reduction in LV volume (103±14–80±16 mL; P=0.02) and major‐axis length (91±5–88±7 mm; P=0.003). All subjects lost an equivalent amount of body mass (3.4±0.2 kg control; 3.1±0.04 kg exercise; 2.8±0.1 kg protein). Cardiac atrophy occurs in women similar to men following sedentary 60 days HDT bed rest. However, exercise training and, to a lesser extent, protein supplementation may be potential countermeasures to the cardiac atrophy associated with chronic unloading conditions such as in spaceflight and prolonged bed rest.     

Physician-Patient Communication in the Urban Clinical Setting

Improving communication between doctor and patient can help meet the objective of providing high-quality, cost-effective, accessible health care. The benefits of effective communication are considerable. Studies indicate that good physician-patient communication can improve diagnostic accuracy and treatment adherence, increase the satisfaction of doctor and patient, and thereby reduce the risk of malpractice suits. Communication in the urban clinical setting comes with a unique set of difficulties. The sociocultural differences between doctor and patient tend to be more pronounced, the interactions with patients more short-term, and the resulting medical encounters of a more impersonal nature. Physicians and patients frequently differ on role expectations for one another. It is nevertheless possible to effect successful communication in the urban medical environment and strengthen the partnership—the “social system”—that exists between doctor and patient. The Miles Institute for Health Care Communication has developed a model, known as the ABCDE approach, that may help facilitate communication in the urban setting. In this article the techniques of the ABCDE model are summarized and a case study is used to show how these techniques might be applied.     

Incidence of spontaneous hearing threshold shifts during modern concert performances.

OBJECTIVES: Concerts have long periods of intense sound with short break intervals. Hearing concerns are well known to performers; concertgoers largely ignore them. Preperformance and postperformance audiograms were compared to assess hearing threshold shifts with and without earplugs. METHODS: A prospective, randomized study in which 29 volunteers attended 3 concerts, encompassing 3 music genres. Audiograms, seating location, sound intensity, and earplug-use data were collected. Data were analyzed to determine frequency test-retest variability. RESULTS: Sound levels averaged 99.8 dBA, and the maximum was 125.6 dBA. Sixty-four percent (9/14) of participants without earplugs showed significant threshold shifts compared with 27% (4/15) of those using earplugs. No significant differences existed between music genres or seating location. CONCLUSIONS: This study showed a high incidence of threshold shifts in unprotected concertgoers. Sound levels exceeded all Occupational Safety and Health Act rules despite standardized sound systems. A significant reduction in threshold shifts was seen with the use of earplugs. EBM rating: A-1b.     

Incompatibility of contrast agents with intravascular medications. Work in progress

In vitro and in vivo precipitation of iodinated contrast agents when ioxaglate and papaverine are given together has been reported. To verify these reports and to investigate other medications not previously tested, the authors analyzed mixtures of contrast agents and medications in vitro with a light spectrophotometer and observed them for visible precipitates for up to 120 minutes. Previously reported incompatibilities between ionic or low-osmolality contrast media and medications were verified, and several new incompatibilities were discovered. No incompatibilities were found when the drugs tested were mixed with the new nonionic contrast media.     

Crohn's disease of the upper gastrointestinal tract

Involvement of the upper gastrointestinal tract by Crohn's disease is being recognized with increasing frequency. Gastroduodenal disease is more common, although esophageal disease is now noted infrequently as well. There is nearly always concomitant involvement of the small bowel or colon. Initial phases of the disease are manifested as superficial inflammatory changes of the mucosa but can progress to scarring and stenosis. Optimum double-contrast technique is necessary to detect these early lesions.