Tyrosine-dependent and -independent mechanisms of STAT3 activation by the human granulocyte colony-stimulating factor (G-CSF) receptor are differentially utilized depending on G-CSF concentration

The granulocyte colony-stimulating factor receptor (G-CSF-R) activates multiple STAT proteins. Although the membrane-proximal cytoplasmic region of the G-CSF-R is necessary and sufficient for activation of STAT1 and STAT5, activation of STAT3 requires the membrane distal region that contains four tyrosines. Although one of these (Y704) has previously been shown to be involved in STAT3 activation from a truncated G-CSF-R derived from a patient with severe chronic neutropenia (SCN), this tyrosine is not required for STAT3 activation by the full-length G-CSF-R. To investigate possible alternative mechanisms of STAT3 activation, we generated a series of Ba/F3 cell transfectants expressing the wild-type G-CSF-R or mutant receptors that either completely lack tyrosines or retain just one of the four cytoplasmic tyrosines of the G-CSF-R. We show that, at saturating G-CSF concentrations, STAT3 activation from the full-length G-CSF-R is efficiently mediated by the C-terminal domain in a manner independent of receptor tyrosines. In contrast, at low G-CSF concentrations, Y704 and Y744 of the G-CSF-R play a major role in STAT3 activation. Both tyrosine-dependent and -independent mechanisms of STAT3 activation are sensitive to the Jak2 inhibitor AG-490, follow similar kinetics, and lead to transactivation of a STAT3 reporter construct, indicating functional equivalence. STAT3 activation is also impaired, particularly at nonsaturating G-CSF concentrations, in bone marrow cells from mice expressing a truncated G-CSF-R (gcsfr-triangle up715). These findings suggest that G-CSF-induced STAT3 activation during basal granulopoiesis (low G-CSF) and "emergency" granulopoiesis (high G-CSF) are differentially controlled. In addition, the data establish the importance of the G-CSF-R C-terminus in STAT3 activation in primary cells, which has implications for understanding why truncated G-CSF-R derived from SCN patients are defective in maturation signaling.     

In situ, High-Resolution Measurement of Dissolved Sulfide Using Diffusive Gradients in Thin Films with Computer-Imaging Densitometry

The technique of diffusive gradients in thin films (DGT) has been developed for the measurement of dissolved sulfide. Sulfide species from the sampled waters diffuse through a polyacrylamide hydrogel and then react with pale yellow AgI((s)), incorporated at the surface of a second gel, to form black Ag(2)S((s)). The accumulated sulfide can be measured with a conventional purge-and-trap method followed by colorimetry (methylene blue). This enables the dissolved-sulfide concentration to be calculated under suitable conditions. Alternatively, the color change in the accumulating gel can be used to measure sulfide. A conventional flat-bed scanner, allied to imaging software, provided a densitometric measurement that was quantitatively related to the amount of sulfide accumulated. DGT measurements on synthetic solutions accurately determined the sulfide concentration (95% recovery), thereby confirming the unobstructed diffusion of HS(-) through the gel. The accumulated mass was inversely proportional to the diffusion-layer thickness as theoretically predicted. With the selected geometry, the limit of detection of the densitometric procedure for a 24-h deployment was 0.13 μmol L(-)(1), and the maximum concentration measurable was 60 μmol L(-)(1). When used in anoxic lacustrine waters, DGT provided sensible concentrations. It was also used to measure depth profiles at submillimeter resolution in estuarine surface sediments.     

A novel application of the infrared coagulator in hair transplantation. Significant reduction of width of the donor site wound

BACKGROUND: The infrared coagulator, a by-product of laser technology, has been used in dermatology in a variety of settings. During hair transplantation sessions, we observed a significant reduction of the donor ellipse width while performing hemostasis with the infrared coagulator. OBJECTIVE: Quantitative assessment of the donor wound width after infrared coagulator use, and correlation to the number of previous transplant sessions and patients' age. METHODS: Twenty-four patients (22 men, two women) underwent hair transplantation. The infrared coagulator was utilized for hemostasis with a pulse duration of 2.5 seconds. RESULTS: The infrared coagulator produced an average donor area decrease of 42%, while achieving rapid hemostasis. No correlation was demonstrated to number of previous transplant sessions or patients' age. CONCLUSIONS: The infrared coagulator significantly decreases the donor wound width while providing hemostasis. Advantages include the potential of larger donor strip harvest, minimal tissue manipulation, and less traumatic closure.     

On vitamin B1 metabolism in avitaminosis and its correction with thiamine and taurine

The levels of phosphate esters and the activities of thiamine biotransformation enzymes in the blood and tissues of albino rats were studied during oxythiamine-induced B1 deficiency and after metabolic correction with thiamine and taurine. Among thiamine phosphates, the most informative indicators of thiamine deficiency were shown to be triphosphate esters and free thiamine diphosphate. The biosynthetic enzymes thiamine kinase and thiamine diphosphate kinase played a decisive role in maintaining the initial rate and in recovering the physiologically active forms of vitamin B1. The activation of hydrolytic enzymes of thiamine phosphate esters occurred by producing abundant free thiamine diphosphate and thiamine triphosphate. Within the first hours, taurine favoured the acceleration of phosphoester biosynthesis and, accumulating in the tissues, inhibited vitamin phosphorylation reactions.     

Expression of interleukin-6 in polymorphic reticulosis--immunohistochemical study of 5 cases

Peripheral T cell lymphoma encompasses lymphomas with a variety of histologic appearances and clinical patterns. Recently, it has been suggested that almost all of the histologic features described under the name of polymorphic reticulosis(PR), lethal midline granuloma, and midline malignant reticulosis can be included in those generally described for malignant lymphomas of peripheral T cell origin(PTCL). There have been few studies of pathogenesis or tissue damage mechanism in PR patients. The need for a precise mechanism for tissue damage has important therapeutic implications. Using immunohistochemical methods with polyclonal anti IL-6 antibody, the authors describe 5 cases of PR with clinically and pathologically typical PR demonstrating a high expression of IL-6. According to classification, 2 cases of grade 1 PR showed the highest expressions, and 2 cases of grade 2 PR with atypical lymphoid cells showed moderate activity, but one case progressed into frank lymphoma(grade 3) and lost IL-6 expression. This strongly implies that some cases of PR have a different mechanism of tissue damage from frank PTCL, despite the one disease spectrum. Further studies on more cases may help clarify the pathogenesis.     

Radiation damage of purple membrane at low temperature.

The intensities of diffracted electron beams for the purple membrane of Halobacterium halobium are found to decay exponentially as a function of the accumulated electron exposure, both at room temperature and at -120 degrees C. This permits us to define the "critical dose" Ne(h,k) for the (h,k) diffracted beam, as being the electron exposure (electrons/A2) at which the diffracteed intensity has fallen to e-1 of its initial value. The critical of purple membrane is found to increase from the room temperature value by at least a factor of four when the specimen is maintained at a temperature of -120 degrees C on a liquid-nitrogen-cooled stage. A relationship derived between the critical dose, Ne, and the dose for optimum imaging, Nopt. Both Ne and Nopt depend, of course, upon the spatial frequency, or resolution. The derivation is valid only for the case in which all sources of noise other than quantum fluctuations are neglected. In this case, Nopt approximately equal to 2.5Ne. Finally, Nuclear Track Emulsion plates have been shown to be advantageous for recording high resolution electron diffraction patterns of small (1 micrometer 2) patches of crystalline biological materials.