Phase stability, brittle-ductile transition, and electronic structures of the TiAl alloying with Fe, Ru, Ge, and Sn: a first-principle investigation

Phase stability, brittle-ductile transition, and electronic structures of M (M = Fe, Ru, Ge, and Sn) and content change of L10-TiAl (γ-TiAl) and B2-TiAl (β-TiAl) have been investigated using first-principle methods. It is found that M metal atoms preferentially occupy the Al (2e) sites in L10-TiAl and B2-TiAl. According to Pugh's ratio and Poisson's ratio, the brittle-ductile transition is predicted for L10-TiAl and B2-TiAl with Fe, Ru, Ge, and Sn. It is found that the brittle-ductile transition from brittle regions to ductile regions with the transition metal elements Fe and Ru in L10-TiAl and B2-TiAl at the low concentration is approximately from 0 to 6.25 at.%. However, the brittle-ductile transition of Ge and Sn at the high concentration approximates from 6.25 to 12.5 at.% in L10-TiAl, comparing with B2-TiAl which approximates from 12.5 to 18.75 at.%. Electronic structure analysis shows that the improvement of brittleness can be attributed to two factors, including different hybridizations of Al-2p (Ti-3d) orbits with Fe-3d (Ge-4p) and Ru-4d (Sn-5p) orbits and different bandwidths of pseudo-gap. Furthermore, the L10-TiAl and B2-TiAl at low concentration of Fe and Ru can increase the value of ELF, where Ge and Sn atoms become bigger at a high concentration in L10-TiAl and B2-TiAl. At last, elastic constant (C_ij), bulk modulus (B), shear modulus (G), and Young's modulus (E) of L10 and B2-TiAl with content change are systematically given.

In Vitro Investigation of a New Thin Film Nitinol-Based Neurovascular Flow Diverter

Fusiform and wide-neck cerebral aneurysms (CAs) can be challenging to treat with conventional endovascular or surgical approaches. Recently, flow diverters have been developed to treat these cases by diverting flow away from the aneurysm rather than occluding it. The pipeline embolization device (PED), which embodies a single-layer braided design, is best known among available flow diverters. While the device has demonstrated success in recent trials, late aneurysmal rupture after PED treatment has been a concern. More recently, a new generation of dual-layer devices has emerged that includes a novel hyperelastic thin film nitinol (HE-TFN)-covered design. In this study, we compare fluid dynamic performance between the PED and HE-TFN devices using particle image velocimetry (PIV). The PED has a pore density of 12.5–20 pores/mm2 and a porosity of 65–70%. The two HE-TFN flow diverters have pore densities of 14.75 pores/mm2 and 40 pores/mm2, and porosities of 82% and 77%, respectively. Conventional wisdom suggests that the lower porosity PED would decrease intra-aneurysmal flow to the greatest degree. However, under physiologically realistic pulsatile flow conditions, average drops in root-mean-square (RMS) velocity (VRMS) within the aneurysm of an idealized physical flow model were 42.8–73.7% for the PED and 68.9–82.7% for the HE-TFN device with the highest pore density. Interestingly, examination of collateral vessel flows in the same model also showed that the HE-TFN design allowed for greater collateral perfusion than the PED. Similar trends were observed under steady flow conditions in the idealized model. In a more clinically realistic scenario wherein an anatomical aneurysm model was investigated, the PED affected intra-aneurysmal VRMS reductions of 64.3% and 56.3% under steady and pulsatile flow conditions, respectively. In comparison, the high pore density HE-TFN device reduced intra-aneurysmal VRMS by 88% and 71.3% under steady and pulsatile flow conditions, respectively. We attribute the superior performance of the HE-TFN device to higher pore density, which may play a more important role in modifying aneurysmal fluid dynamics than the conventional flow diverter design parameter of greatest general interest, absolute porosity. Finally, the PED led to more elevated intra-aneurysmal pressures after deployment, which provides insight into a potential mechanism for late rupture following treatment with the device.

Impact of mometasone furoate nasal spray on individual ocular symptoms of allergic rhinitis: a meta-analysis

BACKGROUND

Intranasal corticosteroids (INSs) are a mainstay of treatment of allergic rhinitis (AR) nasal symptoms. The INS mometasone furoate nasal spray (MFNS) has well-documented efficacy and safety for the treatment and prophylaxis of nasal symptoms of seasonal AR (SAR) and for the treatment of nasal symptoms of perennial AR (PAR). Increasing interest has focused on whether INSs, including MFNS, may have beneficial effects on the ocular symptoms frequently associated with AR.

METHODS

We performed a meta-analysis of 10 randomized, placebo-controlled trials of the efficacy of MFNS 200 mcg daily in relieving ocular allergy symptoms, including itching/burning, redness, and tearing/watering in both SAR and PAR. Four PAR studies and six SAR studies are included in the analysis. A fixed-effect inverse variance model was used to calculate weighted mean differences, 95% confidence intervals (CIs) for each comparison, and a combined overall treatment effect (Z) with P-value.

RESULTS

In both analyses of SAR and PAR studies, including 3132 patients, all individual ocular symptoms were reduced in patients treated with MFNS. Overall treatment effect was significant for all three individual ocular symptoms in the SAR studies (Z = 9.18 for tearing, Z = 10.15 for itching, and Z = 8.88 for redness; P < 0.00001 for all) and in the PAR studies (Z = 5.94, P < 0.00001 for tearing; Z = 2.43, P = 0.02 for itching; and Z = 2.42, P = 0.02 for redness).

CONCLUSIONS

Our findings add to the growing body of literature supporting the positive class effect of INSs, including MFNS, on ocular symptoms associated with SAR and PAR.

Restoration of facial form and function after severe disfigurement from burn injury by a composite facial allograft

Composite facial allotransplantation is emerging as a treatment option for severe facial disfigurements. The technical feasibility of facial transplantation has been demonstrated, and the initial clinical outcomes have been encouraging. We report an excellent functional and anatomical restoration 1 year after face transplantation. A 59-year-old male with severe disfigurement from electrical burn injury was treated with a facial allograft composed of bone and soft tissues to restore midfacial form and function. An initial potent antirejection treatment was tapered to minimal dose of immunosuppression. There were no surgical complications. The patient demonstrated facial redness during the initial postoperative months. One acute rejection episode was reversed with a brief methylprednisolone bolus treatment. Pathological analysis and the donor's medical history suggested that rosacea transferred from the donor caused the erythema, successfully treated with topical metronidazol. Significant restoration of nasal breathing, speech, feeding, sensation and animation was achieved. The patient was highly satisfied with the esthetic result, and regained much of his capacity for normal social life. Composite facial allotransplantation, along with minimal and well-tolerated immunosuppression, was successfully utilized to restore facial form and function in a patient with severe disfigurement of the midface.

61 EFFECT OF ROOM TEMPERATURE HOLDING PROCEDURE ON ABILITY OF OOCYTES TO MATURE AND DEVELOP IN VITRO AFTER EQUINE SOMATIC CELL NUCLEAR TRANSFER

In Korea, it takes time to transport the ovaries of mares to the laboratory because horses are slaughtered only on Jeju island. Also, initiation of in vitro maturation (IVM) may be a little more delayed because of the oocyte collection by scraping of the follicular wall. It was reported that holding procedure of equine oocytes before IVM did not affect the developmental competence after intracytoplasmic sperm injection (Choi et al. 2006 Theriogenology 66, 955–963). The aims of present study were 1) to investigate the meiotic competence of equine oocytes held before IVM according to the type of oocytes, and 2) to examine the in vitro development after somatic cell nuclear transfer (SCNT). Cumulus–oocyte complexes (COCs) were recovered by scraping and washing of the follicular wall with Dulbecco’s modified Eagle medium (D-MEM) supplemented with 0.05% PVA, and classified as compact (Cp) or expended (Ex) depending on the expansion of cumulus or granulosa cells. 2 types of IVM procedures were compared: 1) COCs were matured immediately in IVM medium (TCM-199 supplemented with 5 mU mL–1 FSH, 50 ng mL–1 EGF, and 10% FBS) at 38.5°C under 5% CO2 in air for 24 to 27 h, and then held in holding medium (40% TCM-199 with Earle’s salts, 40% TCM-199 with Hanks’ salts, and 20% FBS) at room temperature for 6 to 7 h (control); or 2) COCs were initially held in holding medium for 6 to 7 h, and then matured in IVM medium for 24 to 27 h (holding). For SCNT, matured oocytes (pooled) were enucleated and electrically fused with equine skin fibroblasts (2.25 kV cm–1, 20 μs, 2 pulses). Fused couplets were activated with 5 μM ionomycin for 4 min followed by 5 h culture in 2 mM 6-DMAP, and cultured in D-MEM supplemented with 10% FBS and 50 ng mL–1 EGF at 38.5°C under 5% CO2, 5% O2, and 90% N2 for 7 to 9 days. Cleavage and blastocyst formation were evaluated on Days 2 and 8, respectively. All analyses were performed using SAS (version 9.1; SAS Institute Inc., Cary, NC, USA). 4 replicates were conducted from May to June 2010. In Ex oocytes, the maturation rate of the holding group (71.4%; 10/16) was not different from that of the control (65.6%; 44/73), and the rate of degenerated oocytes (4.8%; 1/16) in the holding group was not different from that in the control (5.6%; 5/73). However, in Cp oocytes, the degeneration rate of the holding group (65.0%; 31/49) was higher (P < 0.001) than that of the control (28.4%; 23/83), and the maturation rate of the holding group (20.6%; 12/49) was slightly lower (P = 0.07) than that of the control (46.0%; 38/83). After SCNT, the cleavage rate of the holding group (66.7%; 8/9) was not different from that of the control (60.8%; 14/25), and the rates of blastocyst formation of the control and the holding group were 8.1% (2/25) and 16.7% (2/9), respectively. Although the holding procedure may influence to the degeneration of Cp oocytes, it is considered that the developmental competence of equine oocytes held before IVM is not affected after SCNT.

44 IN VITRO DEVELOPMENT OF INTERSPECIES NUCLEAR TRANSFER EMBRYOS GENERATED WITH BOVINE OOCYTES AND EQUINE SKIN FIBROBLASTS

Study for equine somatic cell nuclear transfer (SCNT) is an attractive field for research, but it has not been a major field of study because it is hard to obtain a sufficient number of ovaries and it takes a lot of time and effort for the recovery of oocytes matured in vivo by ovum pickup. It was reported that the bovine cytoplast could support the remodelling of equine donor cells (Zhou et al. 2007 Reprod. Domest. Anim. 42, 243–247). The objectives of this study are 1) to monitor the early events of equine SCNT by interspecies SCNT (isSCNT) between bovine cytoplast and equine donor cell, and 2) to investigate the developmental competence of isSCNT embryos. Bovine oocytes were recovered from the follicles of slaughtered ovaries, and matured in TCM-199 supplemented with 10 mU mL–1 FSH, 50 ng mL–1 EGF, and 10% FBS at 39°C under 5% CO2 in air for 22 h. Fibroblasts derived from bovine or equine skin tissues were synchronized at G0/G1 stage by contact inhibition for 72 h. After IVM, oocytes with polar body were enucleated and electrically fused with equine or bovine skin fibroblasts (1.0 kV cm–1, 20 μs, 2 pulses). Fused couplets were activated with 5 μM ionomycin for 4 min followed by 5 h culture in 10 μg mL–1 cycloheximide (CHX) and/or 2 mM 6-DMAP, and cultured in modified synthetic oviduct fluid (mSOF) at 39°C under 5% CO2, 5% O2, and 90% N2 for 7 days. All analyses were performed using SAS (version 9.1; SAS Institute, Cary, NC, USA). The cleavage rate of isSCNT embryos derived from equine cell was not different (252/323, 78.7%; P = 0.94) from that of SCNT embryos derived from bovine cell (230/297, 79.2%). However, the rate of isSCNT embryos developed to over 8-cell stage was lower (3.3%; P < 0.0001) than that of bovine SCNT embryos (39.4%), and total cell number of isSCNT embryos developed to over 8-cell stage was lower (17.5, n = 12; P < 0.0001) than that (80.8, n = 110) of bovine SCNT embryos. Also, the rate of blastocyst formation of isSCNT embryos (0/323; 0.0%) was lower (P < 0.0001) than that of bovine SCNT embryos (83/297; 29.3%). Meanwhile, reconstructed oocytes for isSCNT were fixed at 8 h after activation to investigate the formation of pseudo-pronucleus (PPN) after post-activation treatment with CHX or CHX+6-DMAP. The ratio of oocytes with single PPN after treatment with CHX+6-DMAP (26/35; 74.3%) was not different (P = 0.63) from that of oocytes treated with CHX (24/36; 68.1%). Although isSCNT embryos derived from bovine cytoplast and equine donor cell could not develop to more than the 16-cell stage, it is believed that the results of this isSCNT study could be used for the preliminary data regarding the reprogramming of donor cell in equine SCNT.

80 USE OF THE SHORT DISPOSABLE NEEDLE SYSTEM FOR FOLLICLE ASPIRATION IN MARES

To achieve success in equine somatic cell nuclear transfer (SCNT), it is important to obtain recipient oocytes of good quality. Transvaginal ultrasoundguided follicle aspiration (TVUFA) is one of the methods to obtain recipient oocytes in equine SCNT, but the commercial long double-lumen needle for TVUFA in large animals is not currently purchasable. The aims of the present study were (1) to compare the recovery rate of short disposable needle system (14G) with that of the long double-lumen needle (12G) and (2) to investigate the developmental competency of recovered oocytes after SCNT and embryo transfer (ET). A real-time ultrasound scanner (Mylab30 vet, Esaote, Italy) equipped with a 7.5-MHz convex array transducer (model EC123) housed in a plastic vaginal device with stainless steel needle guidance was used for TVUFA from pre-ovulatory follicles 25 to 40 mm in diameter on synchronized thoroughbred mares between 6 and 9 years of age. Two types of needles were used: (1) a 12G double-lumen long needle (V-EOAD-1260L; Cook, Brisbane, Australia); (2) a 14G single-lumen disposable needle (2.1 × 80mm; Bovi-vet, Kruuse, Denmark) inserted with 18G inner needle (0.8 × 600 mm) using stainless steel connector and tube. Recovered oocytes were matured in vitro in TCM-199 with 5 mU mL-1 FSH (Folltropin-V, Bioniche, Belleville, ON, Canada) and 10% fetal bovine serum (Sigma, St. Louis, MO, USA) for 12 to 16 h. Matured oocytes were enucleated and electrically fused with equine skin fibroblasts (2.25 kV cm-1, 20μs, 2 pulses). Fused couplets were activated with 5 μM ionomycin for 4 min followed by 5 h culture in 1 mM 6-DMAP. Immediately following SCNT procedures, cloned embryos were surgically transferred to the oviducts of recipient mares (n = 2 to 5 embryos per recipient) that had ovulated within 24 hours before the transfer. An initial pregnancy examination was performed using transrectal ultrasonography between Days 14 and 16 (Day 0 = surgery). The recovery rate of the short disposable needle (n = 89, 44.1%) was slightly increased compared with that of the long needle (n = 34, 29.8%), but the difference was not significant. Nineteen SCNT embryos were transferred to 8 mares, and 1 mare is maintaining pregnancy for 60 days. The results of this study demonstrated that our short disposable needle system could be used instead of the commercial long needle and in vivo development of oocyte recovered with the 14G needle could be maintained after nuclear transfer and embryo transfer.

Pyridoxine is not effective for the prevention of hand foot syndrome (HFS) associated with capecitabine therapy: Results of a randomized double-blind placebo-controlled study

9007

Introduction: Although pyridoxine has been used empirically for the prevention of HFS associated with capecitabine, its efficacy has not been proven yet. We performed a prospective randomized double-blind study to determine whether pyridoxine can prevent the development of HFS when given concurrently with capecitabine. Method: Chemotherapy-naive patients (pts) with gastrointestinal tract cancers who were going to have capecitabine-containing chemotherapy were randomized to receive either oral pyridoxine (200 mg/day) or placebo daily during chemotherapy after stratified by chemotherapy regimen: 1) capecitabine alone, 2) capecitabine and cisplatin, or 3) docetaxel, capecitabine, and cisplatin. The patients were observed until grade 2 or 3 HFS (by NCI CTC version 2.0) developed or capecitabine containing chemotherapy ended. When grade 2 or 3 HFS developed in pts in placebo group, the pts were randomized again to receive either pyridoxine or placebo for next cycle of chemotherapy in order to determine whether pyridoxine could improve the HFS. Result: From Jun 2004 to Oct 2005, total 389 pts were entered onto the study. But, 29 pts (15 in placebo group and 14 in pyridoxine group) were excluded from the study because of ineligibility or pts’ refusal. Pts’ characteristics were well balanced between the 2 groups. Grade 2 or 3 HFS developed in 55 of 180 (30.6%) pts in placebo group and in 57 of 180 (31.7%) pts in pyridoxine group. (p=0.788) The median cycles of chemotherapy to grade 2 or 3 HFS was 3 in both groups. The mean cumulative dose of capecitabine until occurrence of grade 2 or 3 HFS was not different statistically between the two groups. (221,157.5 mg/m2 vs. 259,808.5 mg/m2, p=0.788). Total 44 of 55 pts in placebo group who had grade 2 or 3 HFS were randomized to receive either placebo or pyridoxine at next cycle. There was no significant difference between the two groups in the proportion of pts with improvement of HFS (43% vs 48%, p=0.94). Conclusion: These results indicated that pyridoxine is not effective for the prevention of HFS associated with capecitabine therapy.

No significant financial relationships to disclose.

Increased 8-hydroxyguanine formation and endonuclease activity for its repair in ischemic-reperfused hearts of rats

A type of oxidative DNA damage, 8-hydroxyguanine (8-OH-Gua) formation, and the activity for its subsequent repair, 8-OH-Gua endonuclease activity, were examined in an ischemia-reperfusion model of isolated rat hearts. The level of 8-OH-Gua in myocardial DNA was measured by a high performance liquid chromatography (HPLC) equipped with an electrochemical detector, and the 8-OH-Gua endonuclease activity was analysed by the endonuclease nicking assay using a synthetic double-stranded oligonucleotide containing an 8-OH-Gua residue as a substrate. The Langendorff-perfused rat hearts were subjected to 30 or 60 min of global ischemia, followed by reperfusion with an oxygenated or a nitrogenated Krebs-Henseleit solution. The 8-OH-Gua content in the DNA of the ischemic hearts reperfused with an oxygenated solution was three to four times higher than that of the control hearts. The levels of 8-OH-Gua did not increase either in the ischemic hearts reperfused with a nitrogenated solution or in the ischemic-reperfused hearts treated with SOD, mannitol or allopurinol. When the myocardial extract was incubated with the 8-OH-Gua-containing oligonucleotide substrate, a specific cleavage at the site of an 8-OH-Gua residue was detected. The endonuclease activity responsible for this cleavage increased two-fold in the ischemic-reperfused hearts, compared to the control. This study demonstrates that the formation of 8-OH-Gua in DNA as well as the level of its repair process, 8-OH-Gua endonuclease activity, increase in the ischemic-reperfused rat hearts in response to oxidative stress due to higher levels of oxygen free radicals.

Metabotropic glutamate receptor agonists potentiate cyclic AMP formation induced by forskolin or beta-adrenergic receptor activation in cerebral cortical astrocytes in culture

The metabotropic glutamate receptor (mGluR) agonist 1-aminocyclopentane-1S,3R-dicarboxylic acid (ACPD) potentiated the accumulation of cyclic AMP induced by either beta-adrenergic receptor stimulation (isoproterenol) or direct activation of adenylyl cyclase (AC) with forskolin in rat cerebral cortical astrocytes grown in a defined medium. In contrast, ACPD inhibits the cyclic AMP response in astrocytes cultured in a serum-containing medium. Pharmacological characterization indicated that a group I mGluR, of which only mGluR5 is detectable in these cells, is involved in the potentiation of cyclic AMP accumulation. Potentiation was elicited by mGluR I agonists [e.g., (R,S)-3,5-dihydroxyphenylglycine (DHPG)], but not by mGluR II or III agonists; it was pertussis toxin resistant and abolished by procedures suppressing mGluR5 function (phorbol ester pretreatment or DHPG-induced receptor down-regulation). Nevertheless, it appears that products generated through the mGluR5 transduction pathway, such as elevated [Ca2+]i or activated protein kinase C (PKC), are not involved in the potentiation as it was not influenced by either the intracellular calcium chelator BAPTA-AM or the PKC inhibitor Ro 31-8220. An inhibitor of phospholipase C, U-73122, markedly attenuated mGluR5-activated phosphoinositide hydrolysis but did not significantly affect the DHPG potentiation of the cyclic AMP response. A mechanism is proposed in which the potentiating effect on AC could be mediated by free betagamma complex that is liberated after the agonist-bound mGluR5 interacts with its coupled G protein.

Receptor-coupled phospholipase C and adenylyl cyclase function with different calcium pools in astrocytes

Astrocytes express phospholipase C (PLC)-coupled metabotropic glutamate receptors (only mGluR5 is detectable) and adenylyl cyclase (AC)-linked beta-adrenergic receptors. Calcium-sensitive effector enzymes are associated with these signal transduction pathways, but the relevant calcium compartments involved were found to be different. mGluR5-linked PLC responded primarily to extracellular Ca2+, suggesting a close spatial relation between the enzyme and Ca2+ entry channels. On the other hand, the calcium-inhibited AC associated with beta-adrenergic receptors was sensitive to intracellular Ca2+ selectively accessible to intracellular Ca2+ chelation. Furthermore, cAMP formation induced by direct activation of AC by forskolin was less responsive to intracellular Ca2+ chelation than that evoked by the receptor-activated AC, raising the possibility of selective access of the receptor to a pool of calcium-inhibited AC and/or the calcium modulation of some components of the coupling pathway.

Glycogen assay for diagnosis of female genital Chlamydia trachomatis infection

Chlamydia trachomatis can synthesize glycogen at various stages in its developmental cycle. The glycogen content of female genital epithelial cells was detected by anthrone, and the results were compared with those from PCR. A total of 320 cervical samples were examined. Of 92 specimens that were positive by PCR, 78 were positive and 14 were negative by the glycogen assay. Of 228 specimens that were negative by PCR, 220 were negative and 8 were positive by the glycogen assay. The sensitivity and specificity of the glycogen assay obtained from these data were 84.8% (78 of 92) and 96.5% (220 of 228), respectively. Use of the glycogen assay to detect the glycogen content in genital epithelial cells may be helpful in the diagnosis of C. trachomatis infection. This is an easy, fast, and inexpensive assay and can be done in less-sophisticated labs.

Pancreatoblastoma

BACKGROUND

Pancreatoblastoma is a rare pancreatic tumor with distinct acinar and squamoid cell differentiation that generally affects infants and young children. Just over 50 cases have been reported in the literature.

METHODS

Five cases of pathologically proven pancreatoblastoma treated at Seoul National University Hospital from 1984 to 1994 were reviewed. There were three girls and two boys who were 2 years to 5 years of age. All cases came to medical attention because of an abdominal mass.

RESULTS

Abdominal pain was observed in one case and anorexia, vomiting, and weight loss in one case. There was marked elevation of serum alpha-fetoprotein (27,000 ng/mL) in one case of liver metastases. Complete excision was performed in two cases in which the tumors were located in the tail of the pancreas. Partial excision was performed in two patients who had unresectable tumors of the head of the pancreas. One patient had an unresectable tumor at diagnosis and needle aspiration biopsy was carried out under ultrasound guidance. Electron microscopy was performed on pathological specimens of three cases and showed zymogen granules but not neuroendocrine granules. Immunocytochemical studies for alpha-fetoprotein, insulin, glucagon and somatostatin were performed in one patient, and results were all negative. Of two patients who underwent complete excision, one patient presented with liver metastases 4 months after operation and received chemotherapy, but died of tumor 6 months after operation. The other patient had local recurrence 1 year after operation. Reoperation and chemotherapy were performed, and the child is now alive without evidence of disease for 32 months. All three patients who had unresectable tumor died of tumor despite adjuvant radiotherapy and chemotherapy.

CONCLUSIONS

The authors emphasize that the diagnosis of pancreatoblastoma in childhood should be suspected with palpation of an abdominal mass, and the chance for cure may be determined by complete excision of the tumor.

Metabotropic glutamate receptor mGluR5 in astrocytes: pharmacological properties and agonist regulation

Metabotropic glutamate receptor (mGluR) agonists induce extensive phosphoinositide (PI) hydrolysis in astrocytes grown in a chemically defined medium with select growth factors. These astrocytes express mGluR5 transcripts, but none of the splice variants of mGluR1, thus permitting the characterization of mGluR5 in a native CNS cell without interference from mGluR1 activity. mGluR5 activation (1) was not associated with stimulation of cyclic AMP formation, (2) showed high sensitivity to the removal of extracellular versus intracellular Ca2+, (3) displayed high coupling efficiency relative to receptor density, and (4) induced PI hydrolysis that was suppressed by phorbol esters with low potency. The rank order of agonist potency was similar to that observed in mGluR1 and mGluR5 transfected cells. The phenylglycine antagonists tested were effective in blocking responses to 1-aminocyclopentane-1S,3R-dicarboxylic acid, but not to glutamate. Prolonged exposure to agonists induced a two-phase desensitization of mGluR5 function, an initial phase (completed by 1 h and plateaus for another 3 h) and a late phase (progressive decrease to approximately 30% of control levels by 24 h). Only the latter phase was associated with receptor down-regulation. Desensitization of mGluR5 function did not involve receptor internalization or phosphorylation mediated by protein kinase C or A; it was purely homologous, and reversible. Resensitization after short agonist treatment did not require prior receptor sequestration. Recovery after prolonged agonist exposure required new protein synthesis, but the restoration of function was more rapid than normalization of receptor protein levels, indicating that regulation also involves other components of the transduction system. The protracted desensitization of mGluR5 in astrocytes suggests that the functions mediated by this receptor are maintained under a variety of conditions ranging from repetitive stimulation to injury responses.

Combined use of time and frequency domain variables in signal-averaged ECG as a predictor of inducible sustained monomorphic ventricular tachycardia in myocardial infarction

BACKGROUND

Time and frequency domain analyses of signal-averaged ECG (SAECG) have several individual limitations, and the results of the two methods sometimes vary considerably. The purpose of this study was to determine whether the combined use of time and frequency domain variables facilitates identification of patients who will have ventricular tachycardia (VT) induced during programmed ventricular stimulation (PVS).

METHODS AND RESULTS

Nine myocardial infarction (MI) patients with clinically documented sustained monomorphic VT (SMVT), 40 MI patients without clinical VT, and 30 normal healthy control subjects were evaluated. PVS using three extrastimuli and SAECG recording were performed in the MI patients on day 36 +/- 4 after infarction. Of 40 MI patients, SMVT was inducible in 14, sustained polymorphic VT in three, nonsustained monomorphic VT in three, nonsustained polymorphic VT in two, and no inducible arrhythmia was obtained in 18. There were significant differences between MI patients with inducible SMVT and without inducible SMVT in the following SAECG variables: filtered QRS durations (high-pass filter setting, 25, 40, and 80 Hz); low-amplitude signal durations (LAS) under 10, 20, 30, and 40 microV (high-pass filter setting, 40 and 80 Hz); root-mean-square voltages (RMS) of the terminal 20, 30, 40, 50, and 60 msec (high-pass filter setting, 40 and 80 Hz); area ratio (area 20-50 Hz/area 0-20 Hz x 10(5)) of a 120-msec sampling interval starting 20 msec before QRS offset; factor of normality on lead X; and minimum value of the variables on lead X, Y, or Z. Stepwise logistic regression analysis selected only LAS under 30 microV (high-pass filter setting, 80 Hz) and area ratio as independent predictors of inducible SMVT. With these two variables, the predicted probability of inducible SMVT [p(VT)] was expressed as p(VT) = 1/[1+exp (6.2-0.11 LAS-0.01 area ratio)]. This function had 93% sensitivity, 81% specificity, 72% positive predictive value, 95% negative predictive value, and 85% predictive accuracy with greater than or equal to 0.3 as the criterion of a positive test.

CONCLUSIONS

The combined use of time and frequency domain analysis of SAECG can enhance the accuracy of this technique as a screening test for results of PVS in MI patients without clinical VT.

Blunt intestinal injury. Keys to diagnosis and management

Fifty-six patients with blunt intestinal injury seen during 39 months were reviewed for keys to diagnosis and treatment. Motor vehicle accidents were involved in 80% of the cases and seat/lap belts were in use 69% of the time. Blunt intestinal injury was the only abdominal injury in 70% of the cases. There were 42 perforations and 20 devascularizations; multiple injuries were common (27%). Abdominal tenderness was present on admission in 43 of 44 patients in whom a reliable examination was possible. Peritoneal lavage was positive in 13 (93%) of 14 patients. Computed tomography was falsely negative in three of four instances in which it was used. Perforations were most common in the upper and lower ends of the small bowel and in the sigmoid colon; devascularizations were most common in the distal ileum and sigmoid colon. Resection/anastomosis was performed in 38% of small-bowel perforations and in all small-bowel devascularizations. Resection/diversion was required in most colonic perforations (five of six patients) and devascularizations (four of six patients). There were five deaths (9%), none due to intestinal injury. There were seven complications related to intestinal injury. Diagnostic delay occurred in two patients; both had resultant morbidity. Blunt intestinal injury is associated with physical findings in conscious patients. Peritoneal lavage should be used when tenderness cannot be evaluated. Timely operative intervention minimizes morbidity and hospital stay.

Treatment of growth hormone deficient patients with recombinant somatropin for 1 year: results of a Chinese multicentre trial

Fifty-nine patients with idiopathic growth hormone deficiency were included in a Chinese multicentre trial of recombinant somatropin, 0.5-0.7 IU/kg/week s.c. given in six or seven divided doses. The height velocity increased from 2.8 +/- 1.0 cm/year to 13.1 +/- 2.5 cm/year during 1 year of treatment, and typical catch-up growth was observed. The increase in height SDS for chronological age was significant, but the increase in height SDS for bone age was not statistically significant. No adverse reactions to the treatment were recorded. Recombinant somatropin was shown to be very effective and safe during the first year of therapy in patients with growth hormone deficiency.

Studies of N-hydroxy-N'-aminoguanidine derivatives by nitrogen-15 nuclear magnetic resonance spectroscopy and as ribonucleotide reductase inhibitors

Hydroxyguanidine, with the imino group of guanidine and the hydroxyamino group of hydroxyurea, has functional groups believed to be important for both anticancer and antiviral activities (Adamson, R.H. Nature (London) 1972, 236, 400-401). Three new N-hydroxy-N'-aminoguanidine derivatives have been synthesized and found to be 20-30 times more active than the hydroxyguanidine itself as inhibitors of ribonucleotide reductase from rat Novikoff tumors (Tai, W.A.; Lai, M.M.; Lien, E.J. "Novel N-Hydroxyguanidine Derivatives as Antiviral Agents", North American Medicinal Chemistry Symposium, University of Toronto, Toronto, Canada, June 20-24, 1982; Abstr, p 144). The character of the tautomeric equilibria, the pKa values, and the protonation sites of these hydroxyguanidine derivatives have been determined by 15N NMR spectroscopy.