Neurotrophic factors in the testis

Neurotrophic factors, interacting with neurons to affect their growth, are a subset of the polypeptide growth factors. There is increasing evidence for a broader physiological role of these factors which includes effects on a variety of nonneuronal tissues. Among the cell systems, where neurotrophic factors have been hypothesized to exert local nonneurotrophic activities, the testis is of particular interest. This organ represents a complex biological unit which requires the concerted action of very diverse cell types interacting with each other in order to ensure correct spermatogenesis. As signaling molecules that may be involved in these intercellular communication events, various neurotrophic factors have attained considerable scientific attention. This article intends to summarize the presently available data on the distribution and possible local activities of neurotrophic factors and their receptors in testicular cells and provides further information on local expression sites of some of these factors in the human testis.Biomedical Reviews 1999; 10: 25-30

The Iceland Microcontinent and a continental Greenland-Iceland-Faroe Ridge

The breakup of Laurasia to form the Northeast Atlantic Realm was the culmination of a long period of tectonic unrest extending back to the Late Palaeozoic. Breakup was prolonged and complex and disintegrated an inhomogeneous collage of cratons sutured by cross-cutting orogens. Volcanic rifted margins formed, which are blanketed by lavas and underlain variously by magma-inflated, extended continental crust and mafic high-velocity lower crust of ambiguous and probably partly continental provenance. New rifts formed by diachronous propagation along old zones of weakness. North of the Greenland-Iceland-Faroe Ridge the newly forming rift propagated south along the Caledonian suture. South of the Greenland-Iceland-Faroe Ridge it propagated north through the North Atlantic Craton along an axis displaced ~ 150 km to the west of the northern rift. Both propagators stalled where the confluence of the Nagssugtoqidian and Caledonian orogens formed a transverse barrier. Thereafter, the ~ 400-km-wide latitudinal zone between the stalled rift tips extended in a distributed, unstable manner along multiple axes of extension that frequently migrated or jumped laterally with shearing occurring between them in diffuse transfer zones. This style of deformation continues to the present day. It is the surface expression of underlying magma-assisted stretching of ductile mid- and lower continental crust which comprises the Icelandic-type lower crust that underlies the Greenland-Iceland-Faroe Ridge. This, and probably also one or more full-crustal-thickness microcontinents incorporated in the Ridge, are capped by surface lavas. The Greenland-Iceland-Faroe Ridge thus has a similar structure to some zones of seaward-dipping reflectors. The contemporaneous melt layer corresponds to the 3–10 km thick Icelandic-type upper crust plus magma emplaced in the ~ 10–30-km-thick Icelandic-type lower crust. This model can account for seismic and gravity data that are inconsistent with a gabbroic composition for Icelandic-type lower crust, and petrological data that show no reasonable temperature or source composition could generate the full ~ 40-km thickness of Icelandic-type crust observed. Numerical modeling confirms that extension of the continental crust can continue for many tens of Myr by lower-crustal flow from beneath the adjacent continents. Petrological estimates of the maximum potential temperature of the source of Icelandic lavas are up to 1450 °C, no more than ~ 100 °C hotter than MORB source. The geochemistry is compatible with a source comprising hydrous peridotite/pyroxenite with a component of continental mid- and lower crust. The fusible petrology, high source volatile contents, and frequent formation of new rifts can account for the true ~ 15–20 km melt thickness at the moderate temperatures observed. A continuous swathe of magma-inflated continental material beneath the 1200-km-wide Greenland-Iceland-Faroe Ridge implies that full continental breakup has not yet occurred at this latitude. Ongoing tectonic instability on the Ridge is manifest in long-term tectonic disequilibrium on the adjacent rifted margins and on the Reykjanes Ridge, where southerly migrating propagators that initiate at Iceland are associated with diachronous swathes of unusually thick oceanic crust. Magmatic volumes in the NE Atlantic Realm have likely been overestimated and the concept of a monogenetic North Atlantic Igneous Province needs to be reappraised. A model of complex, piecemeal breakup controlled by pre-existing structures that produces anomalous volcanism at barriers to rift propagation and distributes continental material in the growing oceans fits other oceanic regions including the Davis Strait and the South Atlantic and West Indian oceans

Assessment of Telemedicine in Surgical Education and Patient Care

OBJECTIVE: To analyze the value of teleconferencing for patient care and surgical education by assessing the activity of an international academic network. SUMMARY BACKGROUND DATA: The uses of telemedicine include teleeducation, training, and consulting, and surgical teams are now involved, sharing diagnostic information and opinions without the need for travel. However, the value of telematics in surgery remains to be assessed. METHODS: During a 2-year period, weekly surgical teleconferences were held among six university hospitals in four European countries. To assess the accuracy of telediagnosis for surgical cases, 60 randomly selected cases were analyzed by a panel of surgeons. Participants’ opinions were analyzed by questionnaire. RESULTS: Seventy teleconferences (50 lectures and 271 case presentations) were held. Ninety-five of the 114 participants (83.3%) completed the final questionnaire. Eighty-six percent rated the surgical activity as good or excellent, 75.7% rated the scientific level as good or excellent, 55.8% rated the daily clinical activity as good or excellent, and 28.4% rated the manual surgical technique as good or excellent. The target organ was identified in all the cases; the organ structure and pathology were considered well defined in 93.3%, and the fine structure was considered well defined in 58.3%. Diagnosis was accurate in 17 cases (28.3%), probable in 25 (41.7%), possible but uncertain in 16 (26.7%), and not possible in 2 cases (3.3%). Discussion among the remote sites increased the rate of valuable therapeutic advice from 55% of cases before the discussion to 95% after the discussion. Eighty-six percent of the surgeons expressed satisfaction with telematics for medical education and patient care. CONCLUSIONS: Participant satisfaction was high, transmission of clinical documents was accurate, and the opportunity to discuss case documentation and management significantly improved diagnostic potential, resulting in an accuracy rate of up to 95%. Teleeducation and teleconsultation in surgery appear to be beneficial

To fuse or not to fuse in lumbar degenerative spondylolisthesis: do baseline symptoms help provide the answer?

L

The bothersomeness of patient self-rated "complications" reported 1 year after spine surgery

L

The assessment of complications after spine surgery: time for a paradigm shift?

L