Surgical repair of brachial plexus injury: a multinational survey of experienced peripheral nerve surgeons.

OBJECT: Brachial plexus injuries (BPIs) are often devastating events that lead to upper-extremity paralysis, rendering the limb a painful extraneous appendage. Fortunately, there are several nerve repair techniques that provide restoration of some function. Although there is general agreement in the medical community concerning which patients may benefit from surgical intervention, the actual repair technique for a given lesion is less clear. The authors sought to identify and better define areas of agreement and disagreement among experienced peripheral nerve surgeons as to the management of BPIs. METHODS: The authors developed a detailed survey in two parts: one part addressing general issues related to BPI and the other presenting four clinical cases. The survey was mailed to 126 experienced peripheral nerve physicians and 49 (39%) participated in the study. The respondents represent 22 different countries and multiple surgical subspecialties. They performed a mean of 33 brachial plexus reconstructions annually. Areas of significant disagreement included the timing and indications for surgical intervention in birth-related palsy, treatment of neuroma-in-continuity, the best transfers to achieve elbow flexion and shoulder abduction, the use of intra- or extraplexal donors for motor neurotization, and the use of distal or proximal coaptation during nerve transfer. CONCLUSIONS: Experienced peripheral nerve surgeons disagree in important ways as to the management of BPI. The decisions made by the various treating physicians underscore the many areas of disagreement regarding the treatment of BPI, including the diagnostic approach to defining the injury, timing of and indications for surgical intervention in birth-related palsy, the treatment of neuroma-in-continuity, the choice of nerve transfers to achieve elbow flexion and shoulder abduction, the use of intra- or extraplexal donors for neurotization, and the use of distal or proximal coaptation during nerve transfer.

Systemic BCNU enhances the efficacy of local delivery of a topoisomerase I inhibitor against malignant glioma.

PURPOSE: To investigate the ability of systemically delivered BCNU to enhance the activity of either systemically delivered irinotecan (CPT-11) or locally delivered camptothecin from a biodegradable polymer for treatment of an intracranial 9L gliosarcoma. METHODS: We used a single systemic dose of BCNU on treatment day 1 in combination with systemic doses of CPT-11 on treatment days 1-5 and 8-12 against an intracranial rat 9L gliosarcoma model implanted into female Fischer 344 rats. We also used the same systemic dose of BCNU given on treatment day 1, followed by a local dose of a 20% loaded camptothecin biodegradable polymer implanted on the same day. RESULTS: Two doses of CPT-11 (10 and 60 mg/kg) were delivered systemically against intracranial 9L. Neither dose showed an increase in survival compared to controls ( P>0.2 for 10 mg/kg and P=0.17 for 60 mg/kg). Systemic delivery of CPT-11 (10 mg/kg per day) in combination with systemic BCNU (15 mg/kg) did not show a significant effect on survival compared to systemic BCNU alone ( P>0.2), even at the maximally tolerated systemic dose of CPT-11 (60 mg/kg per day; P=0.06). The combination of systemic BCNU (15 mg/kg) and intracranial delivery of camptothecin (20% loaded polymer), however, significantly extended survival compared to systemic BCNU alone ( P<0.001) and compared to intracranial delivery of camptothecin alone ( P=0.01). CONCLUSIONS: In a 9L gliosarcoma model, systemic delivery of CPT-11 showed no benefit in survival when delivered alone or in combination with systemic BCNU, because CPT-11 is unable to cross the blood-brain barrier in cytotoxic levels. When cytotoxic levels of a topoisomerase I inhibitor are delivered directly to the brain tumor via a biodegradable polymer, however, the systemic delivery of the alkylating agent BCNU significantly enhances the antitumor effects of camptothecin in a 9L gliosarcoma model.

Polymer delivery of camptothecin against 9L gliosarcoma: release, distribution, and efficacy.

Camptothecin is a potent antineoplastic agent that has shown efficacy against multiple tumor lines in vitro; unfortunately, systemic toxicity has limited its in vivo efficacy. This is the first study to investigate the release, biodistribution, and efficacy of camptothecin from a biodegradable polyanhydride polymer. Tritiated camptothecin was incorporated into biodegradable polymers that were implanted intracranially in 16 male Fischer 344 rats and the animals were followed up to 21 days post-implant. A concentration of 11-45 microg of camptothecin-sodium/mg brain tissue was within a 3 mm radius of the polymer disc, with levels of 0.1 microg at the outermost margin of the rat brain, 7 mm from the site of implantation. These tissue concentrations are within the therapeutic ranges for human and rat glioma lines tested against camptothecin-sodium in vitro. The in vivo efficacy of camptothecin-sodium was evaluated with male Fischer 344 rats implanted intracranially with 9L gliosarcoma and compared with the efficacy of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). The animals were divided into four groups. Group 1 (control) had a median survival of 17 days. Group 2 (3.8% BCNU polymer) had a median survival of 23 days (P = 0.006). Group 3 (20% camptothecin polymer) had a median survival of 25 days (P = 0.023). Group 4 (50% camptothecin polymer) had a median survival of 69 days (P < 0.001). Drug loadings of 20% and 50% camptothecin released intact camptothecin for up to 1000 h in vitro. We conclude that the biodegradable polymer p(CPP: SA) releases camptothecin-sodium, produces tumoricidal tissue levels, results in little or no systemic toxicity, and prolongs survival in a rat glioma model.

UDP-glucuronate decarboxylase, a key enzyme in proteoglycan synthesis: cloning, characterization, and localization.

UDP-glucuronate decarboxylase (UGD) catalyzes the formation of UDP-xylose from UDP-glucuronate. UDP-xylose is then used to initiate glycosaminoglycan biosynthesis on the core protein of proteoglycans. In a yeast two-hybrid screen with the protein kinase Akt (protein kinase B), we detected interactions with a novel sequence, which we cloned and expressed. The expressed protein displayed UGD activity but did not display the activities of homologous nucleotide sugar epimerases or dehydratases. We did not detect phosphorylation of UGD by Akt nor did we detect any influence of Akt on UGD activity. Effects of UGD on Akt kinase activity were also absent. Northern blot and Western blot analyses revealed the presence of UGD in multiple tissues and brain regions. Subcellular studies and histochemistry localized UGD protein to the perinuclear Golgi where xylosylation of proteoglycan core proteins is known to occur.

Akt-dependent phosphorylation of endothelial nitric-oxide synthase mediates penile erection.

In the penis, nitric oxide (NO) can be formed by both neuronal NO synthase and endothelial NOS (eNOS). eNOS is activated by viscous drag/shear stress in blood vessels to produce NO continuously, a process mediated by the phosphatidylinositol 3-kinase (PI3kinase)/Akt pathway. Here we show that PI3-kinase/Akt physiologically mediates erection. Both electrical stimulation of the cavernous nerve and direct intracavernosal injection of the vasorelaxant drug papaverine cause rapid increases in phosphorylated (activated) Akt and eNOS. Phosphorylation is diminished by wortmannin and LY294002, inhibitors of PI3-kinase, the upstream activator of Akt. The two drugs also reduce erection. Penile erection elicited by papaverine is reduced profoundly in mice with targeted deletion of eNOS. Our findings support a model in which rapid, brief activation of neuronal NOS initiates the erectile process, whereas PI3-kinase/Akt-dependent phosphorylation and activation of eNOS leads to sustained NO production and maximal erection.

Phospholipase C gamma 1 is a physiological guanine nucleotide exchange factor for the nuclear GTPase PIKE.

Phospholipase C gamma 1 (PLC-gamma 1) hydrolyses phosphatidylinositol-4,5-bisphosphate to the second messengers inositol-1,4,5-trisphosphate and diacylglycerol. PLC-gamma 1 also has mitogenic activity upon growth-factor-dependent tyrosine phosphorylation; however, this activity is not dependent on the phospholipase activity of PLC-gamma 1, but requires an SH3 domain. Here, we demonstrate that PLC-gamma 1 acts as a guanine nucleotide exchange factor (GEF) for PIKE (phosphatidylinositol-3-OH kinase (PI(3)K) enhancer). PIKE is a nuclear GTPase that activates nuclear PI(3)K activity, and mediates the physiological activation by nerve growth factor (NGF) of nuclear PI(3)K activity. This enzymatic activity accounts for the mitogenic properties of PLC-gamma 1.