Effects of local administration of interferon-beta on proliferation of retinal pigment epithelium in rabbit after laser photocoagulation

PURPOSE: To investigate whether local administration of interferon (IFN)-beta promotes proliferation of the retinal pigment epithelium (RPE) in vivo. METHODS: Following local injection of IFN-beta into the sub-Tenon space of rabbit eyes, the penetration of IFN-beta into various intraocular areas was determined by means of enzyme-linked immuno-adsorbent assay. Retinal lesions were produced by laser photocoagulation (PC), and IFN-beta (1 x 10(6) IU, 1 x 10(5) IU, or 1 x 10(4) IU) was administered into the sub-Tenon space. Physiological saline was substituted for IFN-beta in controls. The proliferation of RPE cells was inspected histopathologically. RESULTS: After IFN-beta administration, IFN-beta was found in all intraocular areas examined, with the highest concentration detected in the choroid. After PC, profuse proliferation of RPE cells began earlier in the rabbits that received the highest dose of IFN-beta than in the control rabbits; repair of the central part of the coagulated lesion in those rabbits was complete within 7 days after PC. In control rabbits, the histopathologic wound repair process proceeded more slowly and to a limited extent. Proliferation of RPE cells in the low and medium dose IFN-beta-treated rabbits was similar to that in the control rabbits. CONCLUSION: The present study demonstrates that repair of the PC-induced retinal lesions, particularly the proliferation of RPE cells, is promoted in vivo by local administration of IFN-beta.     

Tachyphylaxis associated with continuous cisatracurium versus pancuronium therapy

STUDY OBJECTIVES: To compare dosing requirements over time among patients receiving continuous cisatracurium versus pancuronium therapy, and to identify factors that may account for changes in pancuronium versus cisatracurium infusion requirements over time. DESIGN: Retrospective, comparative cohort analysis. SETTING: A tertiary level 1 trauma center. PATIENTS: Forty-five consecutive adult patients who were admitted to intensive care units at our institution from January 1998-August 2000 and received continuous cisatracurium or pancuronium therapy for at least 48 hours. MEASUREMENTS AND MAIN RESULTS: Dosing requirements of patients treated with pancuronium or cisatracurium were recorded over time throughout the treatment period. Factors that could affect dosing requirements of a neuromuscular blocking agent (NMBA) were stratified as time invariant (admitting service, acute physiology and chronic health evaluation II score, duration of mechanical ventilation, pressure control ventilation, baseline hepatic or renal insufficiency, thermal injury, train-of-four assessment, and concurrent drug administration or disorders affecting neuromuscular transmission) or time variant (concurrent sedation and narcotic analgesia therapy; serum magnesium, potassium, and creatinine concentrations; arterial pH level; temperature; peak airway pressure; and partial pressure of oxygen:fraction of inspired oxygen ratio). Hierarchical linear modeling was used to compare the dosing requirements and to identify confounders affecting the relationship. The infusion rate escalation for the cisatracurium group was greater (0.39 microg/kg/min; 95% confidence interval [CI] 0.22-0.56; 23 patients) than for the pancuronium group (-0.06 microg/kg/min; 95% CI -0.24-0.12; 22 patients; p<0.001) and was associated with an average daily cost/patient significantly higher (p<0.001) with cisatracurium ($258+/-$114) than pancuronium ($11+/-$5). Confounder analysis revealed that only the admitting service and the number of times the NMBA infusion was suspended because no twitch was detected differed between groups. Neither of these confounders significantly affected the temporal relationship between cisatracurium and pancuronium infusion rates. CONCLUSION: Dosing requirements increase over time at a significantly greater rate for cisatracurium than pancuronium infusions. Tachyphylaxis with cisatracurium is associated with substantial drug-related costs and is not accounted for by various disease-, patient-, and therapy-related factors. Further investigation is required to elucidate the mechanisms and risk factors underlying this phenomenon.     

Changes of serum alpha 2u-globulin in the subacute oral toxicity study of ethynyl estradiol and bisphenol A based on the draft protocol for the 'Enhanced OECD Test Guideline No. 407'

To investigate the usefulness of serum alpha 2u-globulin changes as a new parameter for detecting endocrine-mediated effects, we performed a 28-day repeated-dose toxicity study using the administration of bisphenol A (BPA) or ethynyl estradiol (EE) in male rats, based on the draft protocol of the 'Enhanced OECD Test Guideline 407 (enhanced TG 407)'. BPA at doses of 0, 40, 200 and 1000 mg/kg per day or EE at doses of 0, 15, 75 and 375 microg/kg per day were orally administered to SD rats. The highest dose of BPA was reduced to 600 mg/kg per day from the second week of the study onwards because a male rat given 1000 mg/kg per day of BPA died within the first week, showing toxic clinical signs. In the assay using BPA, a reduction in the level of alpha 2u-globulin was detected in the group receiving a dose of 600 mg/kg per day. Reductions in the absolute and relative ventral prostate weights were only observed in the 600 mg/kg per day group. In the assay using EE, the alpha 2u-globulin level decreased significantly in the 375 microg/kg per day group. A reduction in the absolute and relative dorsolateral prostate weights was also observed in the 75 and 375 microg/kg per day groups, morphologically abnormal sperm were observed in the 375 microg/kg per day group. Furthermore, atrophic changes in the prostate and seminal vesicle and degenerative changes in the testis were observed in the 375 microg/kg per day group. Although the alpha 2u-globulin level was reduced in this assay using BPA and EE, further studies are necessary before this assay becomes a useful method for detecting endocrine-mediated effects.     

Tropane alkaloids in adventitious root cultures of Physochlaina physaloides

Adventitious root cultures of Physochlaina physaloides were established and their growth and tropane alkaloid production were investigated. Although the roots cultured in Murashige-skoog liquid medium containing 1.0-3.0 mg/l IBA grew well, the addition of lower concentrations of auxins was more suitable for alkaloid production. The best alkaloid yield was obtained with 0.01 mg/l NAA in 1/2 MS liquid medium. In addition, the alkaloid differences between the cultured roots and the regenerated plant cultivated in the soil was studied. Cultured roots in this condition showed higher level of alkaloids when compared to leaf, stem and roots from the regenerated plant (3 months in field conditions).     

Role of perivascular sympathetic nerves and regional differences in the features of sympathetic innervation of the vascular system

Maintenance of blood pressure is mostly dependent on sympathetic "tone", and the sympathetic nerve innervates the entire vascular bed, excepting the capillaries. Although norepinephrine (NE) is the principal neurotransmitter released upon sympathetic nerve stimulation, neuropeptide Y and ATP are cotransmitters in various vascular tissues. In addition, dopamine and epinephrine, as well as acetylcholine, have been shown to be sympathetic neurotransmitters in specific vasculatures. Transmitter NE release is modified by a number of endogenous substances including the transmitter itself. Chronic denervation of the preganglionic fiber induces an increase in NE release per pulse, indicating postganglionic neuronal supersensitivity. So far, three main adrenoceptor types have been shown, alpha1, alpha2 and beta, each of which is further divided into at least three subtypes, as well as the alpha1L-adrenoceptor, a phenotype of the cloned alpha1a-adrenoceptor, in the blood vessel. Thus, the response of vessels with different receptor types to a transmitter varies quantitatively and even qualitatively from one vessel to another. The remarkable diversity in the sympathetic innervation mechanism in the vascular system may play an important role in regional variations in the regulation of blood flow. The sympathetic nerve also exerts long-term trophic action on the blood vessel. In conclusion, the sympathetic nervous system plays an important role not only in the regulation of cardiovascular dynamics but in the maintenance of the vessel structure, as well.     

Antagonistic effects of antimuscarinic drugs on alpha 1-adrenoceptors

We previously observed that noradrenaline (NA)-induced contraction of the portal vein of rabbit was relaxed by the antimuscarinic drugs of atropine sulfate, but not scopolamine hydrobromide. In the present study we examined the possible effect of the antimuscarinic drugs of atropine sulfate, scopolamine hydrobromide, p-fluoro-hexa-hydro-sila-difenidol ( p-F-HHSiD, the M(3)-receptor antagonist) and pirenzepine (the M(1)-receptor antagonist) on alpha(1)-adrenoceptor (AR).Atropine and p-F-HHSiD relaxed the alpha(1)-AR agonist methoxamine-induced contraction of the rabbit portal vein in a concentration-dependent manner; however, scopolamine and pirenzepine had no such inhibitory effect. Radioligand binding studies with the alpha(1)-AR ligand 2-[2-(4-hydroxy-3-[(125)I]iodo-phenyl)ethylaminomethyl]-alpha-tetralone ([(125)I]HEAT) in membrane preparations from mouse whole brain showed that atropine (p K(i)=5.33) and p-F-HHSiD (p K(i)=5.88) had higher affinities than scopolamine (p K(i)=3.17) and pirenzepine (p K(i)<2.70). Furthermore, atropine and p-F-HHSiD had higher affinities for all human cloned alpha(1)-ARs than scopolamine and pirenzepine. The results show that the antimuscarinic drugs atropine and p-F-HHSiD have a direct but weak antagonistic activity against alpha(1)-ARs.     

Porphyrinogenic xenobiotic-induced N-alkylprotoporphyrin IX formation: a bioassay utilizing chick embryo hepatic ferrochelatase

INTRODUCTION: The porphyrinogenicity of some xenobiotics results from mechanism-based inactivation of selected cytochrome P450 (CYP) enzymes accompanied by conversion of prosthetic heme groups to N-alkylprotoporphyrins (N-alkylPPs), some of which inhibit ferrochelatase (FC). Problems have arisen in extrapolating xenobiotic porphyrinogenicity observed in test animals to humans, due in part to differences among CYP enzymes. Our goal was to develop a bioassay to detect N-alkylPPs formed following interaction of porphyrinogenic xenobiotics with rat liver microsomal CYP. METHODS: Seventeen-day-old chick embryo livers were homogenized, and the mitochondrial fraction was isolated. The FC activity of this fraction was determined by means of the pyridine hemochromogen method. Inhibition of FC was used to detect N-alkylPP formation following interaction of porphyrinogenic xenobiotics with rat liver microsomes. RESULTS: The 17-day-old chick embryo hepatic mitochondrial preparation served as a stable source of FC activity, which was linear with respect to time and protein concentration. FC activity was higher than previously reported in a homogenate of 17-day-old chick embryo hepatocytes in culture and in an aqueous extract of 17-day-old chick embryo mitochondria. The EC(50) of N-methylprotoporphyrin IX in the chick embryo liver mitochondrial preparation was similar to that in the homogenate of chick embryo liver cell culture. The FC bioassay could detect N-alkylPPs formed following the interaction of porphyrinogenic xenobiotics with rat liver microsomes containing 2.4-9.0 nmol of CYP. DISCUSSION: In future studies investigating N-alkylPP formation following interaction of xenobiotics with CYP enzymes, we recommend using a combination of a fluorescence technique and the chick embryo hepatic mitochondrial FC assay. This would provide information both on the formation of N-alkylPPs and distinguish between those N-alkylPPs that produced porphyrin accumulation via FC inhibition and those that do not.     

Chinese medicine induces neurite outgrowth in PC12 mutant cells incapable of differentiation

During continuous culture of neural PC12 cells, we obtained a drug-hypersensitive PC12 mutant cell that showed high stimulation of neurite outgrowth by various drugs. When several Chinese medicines such as shu-jing-huo-xie-tang and Wu-Ling-San were provided to these PC12 mutant cells, the frequency of nerve growth factor (NGF)-induced neurite outgrowth increased approximately 30-fold compared to NGF alone. Neurite outgrowth induced by NGF in PC12 cells is accompanied by sustained activation of mitogen-activated protein kinase (MAPK); however, these Chinese medicines did not induce MAPK activity. The findings thus indicate that certain Chinese medicines may induce neurite outgrowth by a novel mechanism which is distinct from the NGF-activated pathway in PC12 mutant cells.     

Characteristics of prophylactic antibiotic strategies after penetrating abdominal trauma at a level I urban trauma center: a comparison with the East guidelines

BACKGROUND: Antibiotic prophylaxis, along with surgical intervention, is a key component in reducing infection in patients after penetrating abdominal trauma (PAT). Recent guidelines from the Eastern Association for the Surgery of Trauma (EAST) recommend that prophylaxis for < or = 24 hours is adequate for most patients. We compared antibiotic prophylaxis practices after PAT at our institution with EAST guidelines, quantified the incidence of infection, and identified risk factors for infection. METHODS: This study was a retrospective review of patients with PAT requiring a therapeutic laparotomy between July 1998 and January 2001. RESULTS: Antibiotic prophylaxis met EAST guidelines criteria in 21 of 97 patients (22%). There was a trend toward higher infection rates (18 of 76 vs. 3 of 21; = 0.273) when prophylaxis exceeded EAST recommendations. Multivariate analysis revealed blood transfusions to be the only predictor of infection (odds ratio, 6.9; 95% confidence interval, 2.42-19.95). CONCLUSION: Despite prophylactic antibiotic use often exceeding EAST criteria, many patients still developed infection. Blood transfusion was the only significant risk factor for infection.