266 THE SHORT TIME TREATMENT WITH SODIUM BUTYRATE ON GERMINAL VESICLE STAGE OOCYTES IMPROVES OOCYTE QUALITY AND DEVELOPMENTAL COMPETENCE IN PIGS

Oocyte maturation is a complex process during which the epigenetic modifications are dramatically changed, especially the histone acetylation and phosphorylation. Sodium butyrate (NaBu) is a histone deacetylase inhibitor that results in a more open structure of DNA. The aim of the present study was to analyse the role of NaBu in the meiosis of porcine oocytes and the subsequent embryonic developmental competence. Cumulus–oocyte complexes (COC) were collected from ovaries obtained at a local slaughterhouse. The COC were randomly divided into 3 groups and matured in vitro in medium (Hao et al. 2006) supplemented with 1 μM NaBu for 2 h [germinal vesicle (GV) stage, group 1] or for 22 h [GV to GV breakdown (GVBD) stage, group 2] or without treatment (control, group 3). After 44 h of in vitro maturation, the oocytes were denuded by 0.2% hyaluronidase, and oocytes with evenly dark ooplasm and visible first polar bodies were considered matured. The cortical granule distribution of matured oocytes was examined with immunostaining. The relative expression of CyclinB and Cdc2 of 3 group oocytes was determined with real-time PCR. Some matured oocytes from each group were collected and stimulated with electric pulse (2 direct current pulses of 1.2 kV cm–1 for 30 μs). The rate of parthenogenetic blastocyst was recorded, and cell number of each blastocyst was determined under an inverted fluorescence microscope after staining with 10 μg mL–1 of Hoechst 33342. The following results were found. 1) Compared with the control group (n = 70, 67.74 ± 1.64), oocyte maturation rates of group 1 and group 2 decreased significantly along with the extended treatments (n = 70, 59.57 ± 5.29 and 46.99 ± 1.22, respectively; P < 0.05). 2) The long time (22 h) treatment with NaBu inhibited the developmental competence (blastocyst rate) of oocytes (n = 30, 15.33 ± 3.47 v. 27.16 ± 2.10 P < 0.05), and the short time (2 h) treatment with NaBu on GV-stage oocytes inhibited the meiotic process slightly but improved the blastocyst rate (n = 30, 33.93 ± 2.51 v. 27.16 ± 2.10; P < 0.05). 3) The short time (2 h) treatment resulted in the migration of more cortical granules into the plasmasmic membrane and formed a monolayer with the membrane (compared with the control). 4) The exposure to NaBu from GV to GVBD stage induced the expression of the CyclinB and Cdc2 in the matured oocytes (4.68 ± 0.45 and 5.80 ± 0.58, respectively; P < 0.05) compared with the control. 5) Short time (2 h) exposure to NaBu on GV-stage oocytes inhibited the expression of the Cdc2 but increased the expression of the CylinB in the matured oocytes (0.43 ± 0.06 and 1.65 ± 0.26, respectively; P < 0.05) compared with the control. In conclusion, results of this study demonstrate that exposure to NaBu inhibits porcine oocyte meiosis in proportion to treatment length. However, a 2-h treatment with 1 μM NaBu improves oocyte developmental competence to the blastocyst stage. These results are useful for improving the developmental competent of oocytes for IVF and in vitro embryo production. This work was supported by a grant (No. 2009CB941001) from the National Basic Research Program of China.

Influence of Cr contents and nanograin sizes on microstructure, mechanical and sliding tribological behaviors of hard Cr-diamond-like carbon films

The influence of Cr content and nanograin size on the microstructure, the mechanical and sliding tribological behaviors of Cr-containing diamond-like carbon (Cr-DLC) films, deposited on (100) Si substrate by a mid-frequency dual-magnetron system, was explored. The Cr-containing nanoparticles (combining Cr with C) were dispersed in the amorphous DLC matrix while some nanoparticles were transformed into compounds of C/Cr. The incorporation of Cr into Cr-DLC films improved the crystallinity of the Cr-rich nanoparticles and partially converted the nanoparticles to Cr/C phase. The films with Cr content ranging between 5-10 at% and with Cr-containing nanograin sizes in range of 15-27 nm were found to possess higher hardness, lower intrinsic stress, lower coefficient of friction (COF) and wear rate than those of 16-28 at% Cr content and 46-74 nm nanograin sizes. The superhard Cr-DLC film with 8.3 at% Cr and 18.4 nm Cr-containing grain gave the favorable micro-tribological characteristics with COF at micro approximately 0.1 and wear rate at 3.6 x 10(-8) mm3/Nm.

Impact of functional bowel symptoms on quality of life and fatigue in quiescent Crohn disease and irritable bowel syndrome

BACKGROUND

Patients with irritable bowel syndrome (IBS) and Crohn disease (CD) have impaired quality of life (Qol) associated with fatigue. Whether IBS-like symptoms have a similar impact on Qol and fatigue in quiescent CD than in IBS is currently unknown. Our aims were (i) to evaluate the prevalence of IBS-like symptoms in quiescent CD and (ii) to compare the impact of IBS-like symptoms on Qol and fatigue in both diseases.

METHODS

A total of 92 quiescent CD, 40 IBS and 20 healthy subjects similar in age were included prospectively in five French academic centers. IBS symptoms were evaluated through the Rome III criteria. The severity of IBS symptoms, Qol, fatigue, depression and anxiety was measured using questionnaires (Francis Score, Likert scales, Fatigue Impact Scale, short-form Beck and Hospital Anxiety and Depression Scale).

KEY RESULTS

Irritable bowel syndrome-like symptoms were found in 42/92 (45.6%) patients with quiescent CD. The presence of IBS-like symptoms was associated with significant more profound alterations of Qol, high scores of fatigue, depression, but similar levels of anxiety. Compared to CD patients with IBS-like symptoms, IBS patients had more severe gastrointestinal symptoms and alterations of Qol, but similar scores of fatigue, depression and anxiety. In quiescent CD patients, fatigue was independently associated with the presence of IBS-like symptoms (OR = 1.018, 95% CI: 1.002-1.034, P = 0.02).

CONCLUSIONS & INFERENCES

The prevalence of IBS-like symptoms is elevated in quiescent CD. The presence of IBS-like symptoms in quiescent CD is probably associated with the range of fatigue/depression disorders. The mechanism underlying the occurrence of IBS-like symptoms in quiescent CD needs to be further explored.

Influence of ag content and nanograin size on microstructure, mechanical and sliding tribological behaviors of Ag-DLC films

Diamonds like carbon (Ag-DLC) films of nine Ag contents were deposited on (100) Si substrate in a mid-frequency dual-magnetron system. The influence of Ag content and nanograin size on the microstructure, mechanical properties and sliding tribological behaviors of the films has been investigated. It is found that (i) the Ag nanocrystallites were dispersed in the amorphous DLC matrix, and increasing Ag content resulted in an upward tendency of the Ag nanocrystallite size; (ii) the films with Ag content ranging between 3.3-11.4 at% and with Ag nanograin sizes in range of 5.4-16.8 nm exhibited higher hardness, lower intrinsic stress, better adhesion, and lower friction coefficient and wear rate as compared with those of 14.7-23.6 at% Ag content and 19.7-34.7 nm nanograin sizes; and (iii) the best combined properties were achieved for the film deposited with 8.7 at% Ag and with grain size 12.9 nm.

Survey of heavy metal pollution and assessment of agricultural soil in Yangzhong district, Jiangsu Province, China

We investigated concentrations of Hg, Cd, Pb, Zn, Cu, As, Ni, and Cr in samples of soil, cereal, and vegetables from Yangzhong district, China. Compared to subsoils, the sampled topsoils are enriched in Hg, Cd, Cu, Pb, Zn, and As. High levels of Cd and Hg are observed in most agricultural soils. Concentrations of Cr and Ni show little spatial variation, and high Cu, Pb, and Zn contents correspond well to areas of urban development. High As contents are primarily recorded at the two ends of the sampled alluvion. The contents of Cd, Hg, and total organic carbon (TOC) increase gradually to maximum values in the upper parts of soil profiles, while Cr and Ni occur in low concentrations within sampled profiles. As, Pb, Cu, and Zn show patterns of slight enrichment within the surface layer. Compared to data obtained in 1990, Cd and Hg show increased concentrations in 2005; this is attributed to the long-term use of agrochemicals. Cr and Ni contents remained steady over this interval because they are derived from the weathering of parent material and subsequent pedogenesis. The measured As, Cu, Pb, and Zn contents show slight increases over time due to atmospheric deposition of material sourced from urban anthropogenic activity. Low concentrations of heavy metals are recorded in vegetables and cereals because the subalkaline environment of the soil limits their mobility. Although the heavy metal concentrations measured in this study do not pose a serious health risk, they do affect the quality of agricultural products.

Association of the spectral features of heart period signal with SNP of NOS in the Chinese Han nationality population

To explore association of the spectral features of heart period signal with SNPs at 5 sites of NOS gene in the subjects (male89, female77, aged 62.40+/-2.5 yrs) by allele specific primer PCR technique. It was found that the TT allelic genotype of NOS2 C-1173T associated with the highest RPH and TT allelic genotype of NOS3 G894T associated with the highest APH in HPS spectral parameters. This suggests the SNPs of NOS2 C-1173T and NOS3 G894T may be the deep layer factors to result in the variability of HPS spectral parameters.

Metabolism of O6-propyl and N6-propyl-carbovir in CEM cells

The metabolism of O6-propyl-carbovir and N6-propyl-carbovir, two selective inhibitors of HIV replication, has been evaluated in CEM cells. Both compounds were phosphorylated in intact cells to carbovir-5'-triphosphate. The metabolism of these two agents was inhibited by deoxycoformycin and mycophenolic acid, but not erythro-9-(2-hydroxy-3-nonyl)adenine. No evidence of the 5'-triphosphate of either compound was detected in CEM cells.

Substrate specificity of human glycinamide ribonucleotide transformylase

The nucleotide substrate specificity of human glycinamide ribonucleotide transformylase, a chemotherapeutic target, has been examined. The enzyme accepts the sarcosyl analog of glycinamide ribonucleotide, carbocyclic glycinamide ribonucleotide, and two phosphonate derivatives of carbocyclic glycinamide ribonucleotide with V/K values, relative to that obtained for beta-glycinamide ribonucleotide, of 1, 27, 1.4, and 2.9%, respectively. Several other analogs of carbocyclic glycinamide ribonucleotide, namely a truncated phosphonate and 2',3'-dideoxy- and 2',3'-dideoxy-2',3'-didehydro-carbocyclic glycinamide ribonucleotide, were inhibitors of the enzyme, competitive against glycinamide ribonucleotide, with Ki values approximately 100 times higher than the Km for -glycinamide ribonucleotide. Although the results of the present study parallel those obtained previously with the avian enzyme (V. D. Antle, D. Liu, B. R. McKellar, C. A. Caperelli, M. Hua, and R. Vince (1996) J. Biol. Chem. 271, 6045-6049), quantitative differences between the two enzyme species have been uncovered.

"First aid for scalds" campaign: reaching Sydney's Chinese, Vietnamese, and Arabic speaking communities

OBJECTIVES

As a serious yet preventable problem, scald injuries in children have been a priority for prevention in Australia and other developed countries. Not only can the occurrence of scalds be prevented, but immediate first aid treatment offers an effective method for secondary prevention, reducing the severity of scalds. Despite the success of scald prevention initiatives, local evidence suggested that first aid knowledge was lacking in some minority ethnic groups. To redress this gap, the "First Aid for Scalds" campaign for those from a non-English speaking background was specifically targeted to three ethnic groups (Vietnamese, Chinese, and Arabic), with the aim of increasing the proportions of parents and caregivers who had correct knowledge of first aid treatment for scalds. The primary strategy was a media campaign, including advertisements on ethnic radio and in ethnic newspapers.

METHODS

The evaluation design included formative research and impact evaluation. The impact evaluation study involved random population based telephone surveys with each of the three language groups, before and after the campaign, to assess the reach and effectiveness of the campaign.

RESULTS

After the campaign, there were significant increases in the proportion of people who knew the correct first aid treatment for scalds. There were substantial variations in campaign recall and knowledge between each of the three language groups. The largest improvement was found in the Vietnamese group.

CONCLUSION

The association between campaign recall and increase in correct knowledge, and the absence of any similar interventions during the campaign period, give credence to the conclusion that the changes observed were a result of the campaign. The results demonstrate the value of community based injury prevention campaigns specifically targeting linguistically diverse communities.

Cervical screening among immigrant Vietnamese women seen in general practice: current rates, predictors and potential recruitment strategies

OBJECTIVE

To ascertain cervical screening rates among Vietnamese women attending Vietnamese-speaking general practitioners (GPs) in Sydney, their recall of opportunistic recruitment by these GPs and their preferences for strategies to encourage screening.

METHOD

Women born in Vietnam aged 18-69 years were recruited through the waiting room of their GP and completed questionnaires in either Vietnamese or Chinese before and after their consultation.

RESULTS

Of 355 women seen during the survey period, 170 were ineligible. Of those eligible, 118 women (64% response rate) completed waiting room questionnaires. Of 86 women 'at risk', 56 (65%) reported having a cervical smear within two years or due on that day; 26 (86%) of those 30 women overdue for screening reported visiting a GP at least twice in the past six months. After adjustment for age and education, women who were more acculturated or had resided in Australia for the most years remained significantly more likely to be screened (p = 0.027 and p = 0.037 respectively). In the follow-up questionnaire, returned by 49 women (52%) who agreed to receive it, recall of opportunistic advice from the GP was low. Female GPs, free screening and more information in Vietnamese were the three most popular recruitment strategies.

CONCLUSION

Study confirms low participation rates in cervical screening by Vietnamese women using self-report. Recent immigrants and the least acculturated are least likely to be screened.

IMPLICATIONS

A community-based strategy involving Vietnamese-speaking GPs shows promise, inviting behavioural evaluation.

Free split and segmental latissimus dorsi muscle transfer in one stage for facial reanimation

The authors report the experience in facial reanimation using free innervated split and segmental latissimus dorsi muscle flap one-stage transfer in 86 patients with longstanding facial palsy. The segmental latissimus dorsi was taken from the distal part of the muscle so that the muscle flap had an ultra-long neurovascular pedicle of 13 to 17.5 cm in length. The muscle flap was made thinner by splitting the segmental muscle. The split segmental muscle flap was transferred to the paralyzed side of the face with its ultra-long neurovascular pedicle passing through a tunnel in the upper lip to the normal side of the face. The neurovascular pedicle of the muscle flap was anastomosed with the facial nerve, artery, and veins, respectively, on the normal side of the face. The operation was designed without the cross-facial nerve graft stage. From 1986 to October of 1997, 86 patients with long-standing facial paralysis were treated in our department. The duration of facial palsy in this series ranged from 1.5 to 51 years. A satisfactory result was obtained in 80 cases, evaluated at 8 months to 2 years postoperatively. The expression movement of the soft tissues of the face can be seen not only over transferred muscle but also on the paralyzed muscle covered by the splitting muscle flap. It is supposed that this is the result of muscle-muscle neurolization. Study of 66 specimens of latissimus dorsi muscle in the cadavers is discussed.

Heterozygous osteopetrotic (op) mutation reduces atherosclerosis in LDL receptor- deficient mice

Previous studies of osteopetrotic (op) mice lacking macrophage colony-stimulating factor (M-CSF) have revealed an inhibition of atherosclerosis development in the apolipoprotein E (apo E)-deficient model and in a diet-induced model. Using LDL receptor-deficient mice, we now show that atheroma development depends on M-CSF concentration, as not only did homozygous osteopetrotic (op/op) mice have dramatically reduced lesions (approximately 0.3% of control lesion size) but heterozygous (op/+) mice had lesions < 1% of controls. Mice heterozygous for the op mutation (op/+) had plasma levels of M-CSF about half those in controls (+/+). The finding that an approximately 2-fold reduction in M-CSF expression reduced lesion size approximately 100-fold suggests the requirement for a threshold level of M-CSF. The effect of M-CSF on atherosclerosis did not appear to be mediated either by changes in plasma lipoprotein levels or alterations in the number of circulating monocytes, since both op/op and op/+ mice exhibited higher levels of atherogenic lipoprotein particles and (op/+) mice showed a near normal number of circulating monocytes. LDL receptor-null littermates of genotypes from op/op, op/+, to +/+ showed monocyte differentials of approximately 4.5, 8, and 10%, respectively. Taken together, these results suggest that the effects of M-CSF on atherogenesis may not be mediated by expression of M-CSF systemically or by modulation of the number of circulating monocytes. These studies support the conclusion that M-CSF participates critically in fatty streak formation and progression to a complex fibrous lesion.

Decrease of very late activation antigen-4 and CD36 on reticulocytes in sickle cell patients treated with hydroxyurea

Sickle cell disease (SCD) is characterized by repeated vaso-occlusive events, which result in substantial morbidity. Abnormal adhesion of sickle red blood cells (RBC) to the vascular endothelium is postulated to play a role in the pathogenesis of vaso-occlusion. Two adhesion receptors, very late activation antigen-4 (VLA-4) and CD36, are found in unusually high numbers on sickle cell reticulocytes and do mediate adhesion of sickle RBC to endothelium. Hydroxyurea (HU) therapy results in fewer vaso-occlusive episodes, and we postulated that HU-related modulation of VLA-4 and CD36 receptors may contribute to its clinical benefit. Using flow cytometry, eight patients were followed from the onset of HU treatment through a mean treatment length of 200 +/- 49 days. Mean corpuscular volume and percent fetal hemoglobin (Hb F) increased from 87% +/- 6% to 98% +/- 9% and 6.6% +/- 3.9% to 12.7% +/- 5.6%, respectively. The percentage of reticulocytes expressing VLA-4 decreased from 29.0% +/- 5.9% to 14.9% +/- 2.3% (P = .0003). Two thirds of the total decrease in VLA-4 expression occurred after 10 weeks of HU and plateaued by 20 weeks. Changes in VLA-4 expression occurred before substantial increases in Hb F. The percentage of reticulocytes expressing CD36 decreased from 55.3% +/- 6.4% to 42.6% (P = .0046). Changes in adhesion receptor expression were not caused by a decrease in reticulocytosis with HU therapy. This report is the first to associate a decrease in adhesion receptor expression with a therapy known to reduce the clinical severity of SCD.

Six-Year Experience with CarboMedics Prosthetic Heart Valves

Between July 1989 and July 1995, 89 CarboMedics prosthetic heart valves were implanted in 70 patients (38 males, 32 females) ranging in age from 13 to 54 years (mean 33 years). Forty-one of these patients underwent mitral valve replacement, 10 had aortic valve replacement, and 19 had double aortic and mitral valve replacement. Early mortality was 4.9%, 0%, and 15.8% respectively in these groups. Mean follow-up time was 3.4 years and was 95.4% complete (3 lost). There were 5 late deaths (7.7%); 1 in the mitral group, 1 in the aortic group, and 3 who had double valve replacements. Three of these late deaths were considered valve-related. The 5-year actuarial survival rates, hospital mortality excluded, were 97% for mitral, 88% for aortic, and 88% for double valve replacement. Preoperatively, 80% of the patients were in New York Heart Association functional class III or IV, whereas postoperatively, 99.5% of the patients were in class I or II. No structural failures were observed. There was 1 case of systemic embolism and 1 case of valve thrombosis, neither of these patients were taking anticoagulants. Hemorrhage was the most frequent complication; 1 of 4 events was fatal. A less intensive warfarin regimen and improvement in hepatic function may reduce hemorrhagic risk while maintaining thromboembolic protection. On the basis of this experience, the CarboMedics prosthetic heart valve appears to be an excellent mechanical prosthesis for cardiac valve replacement, in terms of hemodynamic performance and low thrombogenicity, in patients receiving anticoagulants.

Substrate specificity of glycinamide ribonucleotide synthetase from chicken liver

Several analogs of glycinamide ribonucleotide and phosphoribosylamine have been prepared and evaluated as substrates for glycinamide ribonucleotide synthetase purified from chicken liver. Glycinamide ribonucleotide analogs include side chain modifications wherein the glycine side chain (R = CH2NH2) has been replaced by R = CH2NHCH3 and R = CH2CH2NH2, ribose ring replacement by chiral cyclopentane and cyclopentene derivatives, and phosphate replacement by phosphonates. All of these, with the exception of the O-phosphonate, served as substrates for the reverse enzymatic reaction, with Vmax values comparable to that obtained with glycinamide ribonucleotide, although the Km values ranged from 21 to 118 times the Km for glycinamide ribonucleotide. Analogs of phosphoribosylamine examined as substrates for the forward reaction consist of chiral derivatives of cyclopentane and cyclopentene and a chiral carbocyclic phosphonate. These also served as substrates, with Km values ranging from 5 to 23 times the Km for phosphoribosylamine and with diminished Vmax values. These studies have begun to define the structural features of the nucleotide substrate necessary to support enzymatic activity. Sarcosine (N-methylglycine) and beta-alanine were also accepted as substrates, albeit with reduced affinity compared with glycine.

Substrate specificity of glycinamide ribonucleotide transformylase from chicken liver

Several glycinamide ribonucleotide analogs have been prepared and evaluated as substrates and/or inhibitors of glycinamide ribonucleotide transformylase from chicken liver. The side chain modified analogs, in which the glycine side chain, R = CH2NH2, has been replaced by R = CH2NHCH3 and R = CH2CH2NH2, are substrates, with V/K (relative intensity) of 2.4% and 16.3%, respectively. Several carbocyclic analogs of glycinamide ribonucleotide, including the phosphonate derivative of carbocyclic glycinamide ribonucleotide, did not serve as substrates, but were inhibitors of the enzyme, competitive against glycinamide ribonucleotide, with Ki values ranging from 7.4 to 23.6 times the Km for glycinamide ribonucleotide. However, the O-phosphonate analog of carbocyclic glycinamide ribonucleotide did support enzymatic activity, with V/K (relative intensity) of 0.8%. In addition, glycinamide ribonucleoside was neither a substrate for, nor an inhibitor of, glycinamide ribonucleotide transformylase. Furthermore, alpha-glycinamide ribonucleotide had no effect on enzyme activity. These studies have begun to define the structural features of the nucleotide substrate required to support enzymatic activity.

Detection of altered membrane phospholipid asymmetry in subpopulations of human red blood cells using fluorescently labeled annexin V

The phospholipids of the human red cell are distributed asymmetrically in the bilayer of the red cell membrane. In certain pathologic states, such as sickle cell anemia, phospholipid asymmetry is altered. Although several methods can be used to measure phospholipid organization, small organizational changes have been very difficult to assess. Moreover, these methods fail to identify subpopulations of cells that have lost their normal phospholipid asymmetry. Using fluorescently labeled annexin V in flow cytometry and fluorescent microscopy, we were able to identify and quantify red cells that had lost their phospholipid asymmetry in populations as small as 1 million cells. Moreover, loss of phospholipid organization in subpopulations as small as 0.1% of the total population could be identified, and individual cells could be studied by fluorescent microscopy. An excellent correlation was found between fluorescence-activated cell sorter (FACS) analysis results using annexin V to detect red cells with phosphatidylserine (PS) on their surface and a PS-requiring prothrombinase assay using similar red cells. Cells that bound fluorescein isothiocyanate (FITC)-labeled annexin V could be isolated from the population using magnetic beads covered with an anti-FITC antibody. Evaluation of blood samples from patients with sickle cell anemia under oxygenated conditions demonstrated the presence of subpopulations of cells that had lost phospholipid asymmetry. While only a few red cells were labeled in normal control samples (0.21% +/- 0.12%, n = 8), significantly increased (P < .001) annexin V labeling was observed in samples from patients with sickle cell anemia (2.18% +/- 1.21%, n = 13). We conclude that loss of phospholipid asymmetry may occur in small subpopulations of red cells and that fluorescently labeled annexin V can be used to quantify and isolate these cells.

Possible contribution of a glutathione conjugate to the long-duration action of beta-funaltrexamine

The fumaramate derivative of naltrexone, beta-funaltrexamine (beta-FNA), is a highly selective long-lasting mu opioid receptor antagonist that is active both in vitro and in vivo, presumably as a result of covalent binding to a mu receptor-based sulfhydryl group. Glutathione, which occurs in significant levels in brain and liver, was found to undergo a Michael-type reaction with beta-FNA in the test tube to give a stable conjugate 3 which occurred as an isomeric mixture. When tested in the GPI and MVD smooth muscle preparations, 3 was found to possess one-tenth the agonist activity of beta-FNA is both tissues, but showed no irreversible antagonist activity. The same result was found for the cysteine conjugate 4, except for some irreversible antagonism in the MVD. Both conjugates antagonize the antinociceptive effect of morphine in the mouse radiant heat tail-flick assay on icv administration. This antagonism persisted and actually increased over 24 h and generally paralleled the duration profile of beta-FNA. On sc administration, beta-FNA and 3 showed similar duration of antagonistic effect, while 4 exhibited only marginal activity at the early time interval. When the compounds are compared by the dose to produce equivalent antagonism, beta-FNA and 3 appeared equally effective and accessible by either route, whereas 4 showed a large difference between the two routes. It is possible that the ultra-long antagonism of the conjugates may result from their enzymatic conversion to beta-FNA in the central nervous system in view of the fact that conjugate 5, which cannot be converted to beta-FNA, did not produce antagonism of long duration in vivo. Alternatively, the protracted antagonism could arise from sequestration of 3 and 4 in tissue compartments that interface with mu opioid receptors.