On the need of a sampling strategy in biological monitoring: The example of hexane exposure

Ambient and biological monitoring of hexane exposure were repeatedly carried out in 14 female shoe makers. Airborne hexane (Ci-H) was measured in 4-h samples collected by a diffusive method. Urinary spot samples were collected before, during (at noon), and at the end of a work shift. 2,5-Hexanedione (2,5HD) in urine collected at noon was poorly related to morning Ci-H. End-of-shift 2,5HD were also poorly related to afternoon air samples. The correlation was still relatively low when end-of-shift 2,5HD was related to 8-h TWA Ci-H (r= 0.44; P<0.01 on=" a=" linear=" scale,=" and=">r-0.58, P< 0.01=" on=" a=" log-log=" scale).=" end-of-shift=" 2,5hd=" levels=" estimated=" on=" the=" basis=" of=" pre-shift=" values=" using=" a=" mathematical=" model=" were=" much=" higher=" (2.3=" times=" on=" average)=" than=" those=" experimentally=" measured=" during=" the=" study=" period.=" owing=" to=" its=" relatively=" long=" half-time,=" 2,5hd=" seems=" to=" be=" influenced=" not=" only=" by=" current=" exposure,=" but=" also=" by=" hexane=" absorbed=" during=" the=" day(s)=" preceding=" sampling.=" the=" lack=" of=" a=" sampling=" strategy=" may=" account=" not=" only=" for=" inconsistencies=" between=" environmental=" and=" biological=" data,=" but=" also=" for=" a=" possible=" misuse=" of=" biological=" monitoring=" when=" utilized=" for=" risk=" assessment.=" despite=" sometimes=" poor=" correlations=" with=" ci-h,=" 2,5hd=" may=" still=" be=" preferred=" to=" other=" indicators=" as=" a=" marker=" of=" effective=" internal=" dose.=" a=" sampling=" strategy=" should=" ensure=" that=" measured=" values=" are=" representative=" of=" the=" individual=" risk=" for=" adverse=">     

Twenty-year review of the surgical management of perianal Crohn's disease

PURPOSE: A retrospective analysis of 48 patients treated over a 20-year period (March 1973–April 1993) was undertaken to assess the results of our practice of early surgical intervention in suppurative complications of perianal Crohn's disease. METHODS: All patients were either seen in the office within the last six months or contacted by phone. RESULTS: The average age of our patients was 30 years at initial diagnosis. Thirty-four patients (71 percent) initially presented with intestinal disease and four (8 percent) with only perianal disease. Thirteen patients (27 percent) initially presented with simultaneous intestinal and perianal disease. The various fistulas at initial presentation included 8 intersphincteric (17 percent), 14 transphincteric (29 percent), 11 complex or multiple (23 percent), 5 rectovaginal (10 percent), and 2 unclassified, for a total of 40 patients. Eight patients (17 percent) presented with only an abscess. Eighty five percent of our patients healed after their first procedure, with an average time to heal of 2.8 months. Thirteen (27 percent) patients had recurrences after initial healing of their wounds. The mean time to recurrence after healing was 5.25 years. Fifty-four percent of our recurrences (7 patients) were treated by incision and drainage of an abscess only. Seven of 13 recurrences healed after the second procedure (54 percent), and 5 of 6 healed after a third procedure (83 percent). Only seven (14 percent) of our patients underwent a proctocolectomy during the study period, through September, 1993. Our overall probability of avoiding proctectomy and healing perineal wounds of 86 percent is consistent with published literature. CONCLUSIONS: Early aggressive surgical management of suppurative complications of perianal Crohn's disease before complex management problems ensue results in a high incidence of healing and a low risk of subsequent proctectomy.     

Mesenteric cystic neoformations: Report of two cases

(Received for publication on Apr. 28, 1997; accepted on May 15, 1998)     

Aesthetic considerations in facial reconstructive surgery: The V-Y flap revisited

The subcutaneous pedicled V-Y advancement flap (also known as the kite flap of Dufourmentel) has been described by many authors. Its versatility in reconstructive surgery is well known, both in facial reconstructive surgery as well as surgery of the trunk and extremities. Its advantages in achieving aesthetic reconstruction in specific facial regions have been less well emphasized in the literature. The flap can be designed within natural facial creases and heals inconspicuously because of its widely based subcutaneous or muscle pedicle which incorporates venous and lymphatic drainage over most of its length. The undesirable biscuiting or flap edema frequently observed with other conventional transposition flaps is avoided. We have found the V-Y flap particularly useful in reconstructing the lower eyelid/medial canthus, supra-alar, and nasolabial regions. Our experience with over 40 such flaps is described, and technical considerations in designing and elevating the flap are discussed.     

Noradrenaline transport by rat heart sympathetic nerves: A re-examination of the role of sodium ions

Summary The effect of sodium ion on ³H-(–)-noradrenaline (0.0875 to 0.5 M) transport by rat heart atrial hemi-appendages incubated in vitro has been studied, and the following observations made: a) When sodium was omitted (choline and lithium substitution) there was no evidence for active noradrenaline transport, and only a component that did not show saturation kinetics up to 1 M noradrenaline, remained. b) Omission of sodium or addition of 4×10^–5 M desipramine inhibited noradrenaline transport to exactly the same extent, and their effects were not additive. Alprenolol did not reduce this sodium-independent transport, but tropolone lowered it somewhat. c) No evidence for corticosterone-sensitive noradrenaline transport (uptake-2) was found in this preparation at the low amine concentrations used. d) In control medium, the kinetic parameters of transport were: K _m: 0.59 ± 0.063 M and V _max: 2.44 ± 0.43 (pmoles/mg protein/min). With 26 mM sodium and the rest substituted by choline, K _m:2.26 ± 0.70 M (P0.001) and V _max: 2.74 ± 0.43 (pmoles/mg protein/min) (not significant). Also with 26 mM sodium, but with sucrose substitution, K _m: 0.76 ± 0.13 M (N.S.) and V _max: 1.06 ± 0.13 (pmol/mg/min) (P<0.05). Such results indicate that sodium only modifies the affinity of the transport system for noradrenaline, without changing V _max, and that changes in the latter are only a consequence of a reduction of the ionic strength. e) When noradrenaline transport was studied at different concentrations of external sodium, at constant ionic strength and with precautions to minimize the noradrenaline-releasing effect of low sodium, it was found that the data could be best represented by two hyperbolas placed in series. This suggests that the noradrenaline carrier has two sites for sodium, that do not interact with each other. When the same experiments were repeated in the absence of chloride, it was found that the noradrenaline transport system had lost virtually all its affinity for sodium. f) The effect of prolonged tissue incubation in the absence of sodium was found to produce a relatively small inactivation of noradrenaline transport. Such phenomenon was enhanced by raising the calcium concentration to 2 mM.     

Death and neuroprotection of retinal ganglion cells after different types of injury

In adult Sprague-Dawley rats, retinal ganglion cell survival was investigated after intraorbital optic nerve section and after transient ischemia of the retina induced by elevation of the intraocular pressure or by selective ligature of the ophthalmic vessels. The thickness of the inner nuclear and inner plexiform layers was also assessed after transient periods (120 min) of retinal ischemia induced by selective ligature of the ophthalmic vessels. In addition, we have also investigated the neuroprotective effects of different substances in these paradigms. The intraocular injection of brain-derived neurotrophic factor increased RGC survival after retinal ischemia induced by elevation of the intraocular pressure or by selective ligature of the ophthalmic vessels. The caspase-inhibitor Z-DEVD increased retinal ganglion cell survival after optic nerve section and also after 90 min of retinal ischemia induced by selective ligature of the ophthalmic vessels. The peptide Bcl-2 did not increase retinal ganglion cell survival after optic nerve section but increased retinal ganglion cell survival after 60 or 90 min of retinal ischemia induced by selective ligature of the ophthalmic vessels. Finally, BDNF, nifedipine, naloxone and bcl-2 prevented in part the decrease in thickness of the inner nuclear layer and inner plexiform layer induced by selective ligature of the ophthalmic vessels. Our results suggest that retinal ganglion cell loss induced by different types of injury, may be prevented by substances with neuroprotective effects, by altering steps of the cascade of events leading to cell death.