The effect of polytrauma in persons with traumatic spine injury. A prospective database of spine fractures.

STUDY DESIGN: A mixed cross-sectional survey and cohort study using a prospectively gathered database of persons with traumatic spine injury. OBJECTIVES: To identify demographic and injury mechanism factors that predict greater injury severity, and to determine the effect of injury severity on outcomes in traumatic spine fracture. SUMMARY OF BACKGROUND DATA: Traumatic spine fracture outcome studies have focused on defining type and level of vertebral fracture without considering the severity of associated injuries. In the trauma population, greater injury severity has been shown to be related to worse outcome. No studies have been reported on the effect of injury severity on outcome in the traumatic spine fracture population. METHODS: Prospectively collected data on 830 persons with traumatic spine injury who were admitted to a trauma hospital were reviewed. Patient demographics; injury mechanism; hospital events; and disability, employment, and pain status at discharge, 1 year, and 2 years after injury were recorded. Associations between these factors and trauma severity (Injury Severity Score) were explored using Pearson's correlation and analysis of variance. RESULTS: Trauma was more severe in patients who had been married previously, who were involved in a motor vehicle accident, were ejected from the vehicle, had loss of consciousness, had higher-level and multiple complicated vertebral fractures, or had neurologic deficit. Those more severely injured had longer lengths of stay, more surgery, more complications, higher mortality, more disability, and less return to work. CONCLUSIONS: Persons with traumatic spine injury and polytrauma have poorer short- and long-term outcomes. This high-risk group may require aggressive interventions, more hospital resources, and close follow-up observation after discharge from hospital to optimize outcome.

Enhanced prostaglandin synthesis after ultraviolet-B exposure modulates DNA synthesis of lens epithelial cells and lowers intraocular pressure in vivo.

PURPOSE: To study the functional significance of prostaglandin synthesis after ultraviolet-B (UVB) exposure of cultured human lens epithelial cells and rabbit eyes in vivo. METHODS: Prostaglandin E2 (PGE2) was assayed using a radioimmunoassay (RIA) and mass spectroscopy. An immortalized human lens epithelial cell line (HLE-B3) was exposed to UV irradiation, and the synthesis of PGE2 was compared with the rabbit lens epithelial cell line N/N1003A. Intact human lenses were exposed to UVB in organ culture. [3H]Thymidine incorporation was measured in cultured lens epithelial cells by incubation with the radiolabel. The effects of isobutyl methyl xanthine (IBMX), an inhibitor of phosphodiesterase and of dibutyryl cyclic adenosine monophosphate (cAMP), an analog of cAMP, on PGE2 synthesis and DNA synthesis, were determined. Rabbit eyes were exposed to UVB radiation in vivo. Intraocular pressure was measured at specific times after exposure. Aqueous humor was remove from rabbit eyes, and its PGE2 content was measured by RIA. RESULTS: Cultured human lens epithelial cells (HLE), like rabbit lens epithelial cells (RLE), showed a dose-dependent increase in basal PGE2 synthesis 24 hours after UVB exposure. However, the amount of PGE2 synthesis was 2000-fold higher in the rabbit cells. Ultraviolet-B radiation enhanced the incorporation of [3H]thymidine in lens epithelial cells. Pretreatment of cells with indomethacin reduce PGE2 synthesis and [3H]thymidine incorporation. The human and rabbit cells responded in a similar manner to changes in DNA synthesis after UVB exposure. The addition of IBMX or dbcAMP to indomethacin-treated, UVB-exposed cells restored DNA synthesis toward the levels observed in the UVB-exposed cells. An increase in the concentration of cAMP was observed in lens epithelial cells exposed to exogenous PGE2. PGE2 synthesis in intact human lenses also increased twofold 24 hours after UVB exposure. Exposure of the rabbit eye in vivo to an optimal dose of UVB produced an increase in the PGE2 levels of the lens and the aqueous humor. Measurements of the intraocular pressure (IOP) of the animals showed a decrease in IOP by 2.21 +/- 0.66 and 6.45 +/- 0.79 mm Hg (mean +/- SEM, P = 0.004, t-test) at 6 and 24 hours after UVB exposure, respectively. The decrease in IOP was prevented by pretreatment with indomethacin. Exposure of the rabbit lens to UVB radiation in vivo enhanced [3H]thymidine incorporation twofold into the lens. Pretreatment of rabbits with indomethacin before exposure reduced this response. CONCLUSIONS: Results indicate that UVB exposure enhances PGE2 synthesis in HLE cultures as well as in rabbit lenses irradiated in vivo. This increased PGE2 synthesis is related to the increase in DNA synthesis observed after UVB treatment. The modulation of DNA synthesis in cultured lens epithelial cells after UVB exposure may be mediated by a cAMP-dependent mechanism.

Nucleotide sequences of three H-2K and three H-2D complementary DNA clones coding mouse class I MHC heavy chain proteins.

OBJECTIVES: The polymerase chain reaction (PCR)-based method was used to obtain and sequence three H-2K and three H-2D mouse complementary DNAs (cDNA) of class I major histocompatibility complex (MHC) molecules. METHODS: Messenger RNA was isolated from Conconavalin A-activated splenocytes of C57BL/10 (H-2b), C3H (H-2k), and Balb/c (H-2d) mice. We designed H-2K- and H-2D-specific primers as well as a common downstream primer based on previously published mouse class I MHC sequences. Using the PCR method and selective primers we isolated and sequenced H-2Kb and H-2Db cDNAs of C57BL/10, H-2Kk and H-2k cDNAs of C3H, as well as H-2Kd and H-2Dd cDNAs of Balb/c strains. RESULTS: Analysis of the nucleotide sequences documented similarity between our three H-2K cDNA sequences and all mouse MHC class I sequences available in the GenBank. Similarly, our three H-2D sequences were homologous with all mouse class I MHC sequences deposited in the GenBank. Our H-2K and H-2D sequences were also identical to numerous published sequences. CONCLUSIONS: Using these mouse cDNAs, we plan to determine the localization of polymorphic in vivo immunogenic amino acids in class I MHC H-2K and H-2D alloantigens.

Modulation of lens epithelial cell proliferation by enhanced prostaglandin synthesis after UVB exposure.

PURPOSE: The goals of this investigation were to examine the synthesis of prostaglandins after UVB exposure of lens epithelial cells and to investigate their role in cell proliferation. METHODS: Cultured rabbit lens epithelial cells (cell line N/N1003A) were exposed to low levels of UV radiation. Prostaglandins were assayed by radioimmunoassay; products of arachidonic acid metabolism were analyzed by thin-layer chromatography and mass spectroscopy. Cell proliferation was measured by [3H]thymidine incorporation and proliferative autoradiography. RESULTS: Cultured lens epithelial cells exposed to UVB radiation showed a dose-dependent increase in basal prostaglandin synthesis measured 24 hours after UV exposure. At an optimal dose (250 J/m2) of UVB, prostaglandin E2 (PGE2) synthesis was enhanced tenfold. Product identity was confirmed using thin-layer chromatography and mass spectroscopy with authentic standards. Incubation of irradiated cells with exogenous arachidonic acid followed by extraction and thin-layer chromatography revealed that the cultures produced PGE2, prostaglandin I2 (measured as 6-keto-prostaglandin F1 alpha), prostaglandin F2 alpha, and hydroxyeicosatetraenoic acid. The synthesis of all of these products was enhanced threefold in cells exposed to 250-J/m2 UVB. Indomethacin pretreatment eliminated the synthesis of prostaglandins, further confirming their identity. To discover the relationship between PGE2 synthesis and irradiation-induced cell proliferation, [3H]thymidine incorporation into DNA was determined 24 or 48 hours after exposure. These experiments revealed a fivefold increase in incorporation induced by UVB exposure. UVB-enhanced incorporation of thymidine was eliminated by pretreatment of cultures with indomethacin to eliminate PG synthesis. However, when 100 nM PGE2 was added to the indomethacin-treated irradiated cultures, incorporation of the label was restored toward the level detected in the UVB-stimulated cells. Addition of other prostaglandins to the cultures was ineffective. CONCLUSIONS: The results indicate that the synthesis of PGE2 is enhanced by exposure of lens epithelial cells to UVB radiation. PGE2 seems to play a specific role in cell proliferation after UV exposure. This increase in PGE2 synthesis may be important in posterior subcapsular cataract formation in humans and in animals exposed to UVB radiation in vivo.

Tocopherol analogs suppress arachidonic acid metabolism via phospholipase inhibition.

alpha-Tocopherol and three derivatives in which the phytol chain is modified or deleted were examined for their effect on cultured keratinocyte arachidonic acid metabolism. 2,2,5,7,8-Pentamethyl-6-hydroxychromane (PMC), in which the phytol chain is replaced by a methyl group, inhibited basal, bradykinin (BK)- and A23187-stimulated prostaglandin E2 (PGE2) synthesis with an apparent Ki of 1.3 microM. The Ki of the analogue with six carbon atoms in the side chain (C6) was 5 microM while that of the C11 analogue was 10 microM. No effect of alpha-tocopherol was observed. The mechanism of inhibition was studied using PMC. The effect of PMC on phospholipase and cyclooxygenase activity was assayed using stable isotope mass measurements of PGE2 formation, which assesses arachidonate release and cyclooxygenase metabolism simultaneously. BK-stimulated formation of PGE2, derived from endogenous phospholipid, was decreased 60% by 5 microM PMC and eliminated by 50 microM PMC, compared with controls. No difference in PGE2 formed from exogenous arachidonic acid was observed, indicating no effect of PMC on cyclooxygenase activity. In contrast, no effect of 5 microM PMC was observed on BK-stimulated [3H]arachidonic acid release from prelabeled cultures. The capacity of PMC to inhibit phospholipase activity in vitro was also assessed. PMC inhibited hydrolysis of phospholipid substrate by up to 60%. These results suggest that alpha-tocopherol analogues with alterations in the phytol chain inhibit eicosanoid synthesis by preferential inhibition of phospholipase.