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PubMed2006

Strategies to improve the fertility of frozen-thawed boar semen for artificial insemination.

Although cryopreservation of boar semen for artificial insemination (AI) was developed 35 years ago, cryopreservation conditions and AI strategies are still considered sub-optimal. AI with excessive numbers of frozen-thawed sperm (5-6 x 10(9) cells), still does not achieve fertility levels similar to AI using liquid semen because of reduced sperm survival. Frozen-thawed (FT) spermatozoa have therefore not been the preferred option for commercial breeding programmes. However, substantial progress has been made regarding boar sperm cryopreservation. Adjustment of cooling and re-warming rates to biophysical properties of boar spermatozoa, new sperm package systems and the achievement of accurately consistent freezing of large numbers of samples using programmable freezers have contributed to post-thaw survival rates above 50%, a threshold similar to that used for bull AI-semen. Moreover, these post-thaw sperm survival rates are consistent within a large population of boars selected for sperm freezability potential, as occurs with AI-bull sires. When such post-thaw boar semen is deposited intra-utero, acceptable fertility (in terms of farrowing rates and litter size) is obtained. Currently, the most effective application of FT-semen for AI is achieved using deep uterine-AI (DUI) which allows placement of a minimal semen dose (in volume 0.5 to 10 mL and sperm number 0.5 to 1 x 10(9) total spermatozoa) into the anterior 1/3 of one uterine horn, with levels of fertility close to AI with liquid semen. However, owing to their shorter life span, FT-boar spermatozoa require an AI-to-ovulation interval not longer than 4-6 h, making peri-ovulatory AI a pre-requisite to obtain the highest possible fertility. Spontaneous ovulation most often occurs when two-thirds of oestrus has passed. Estimation of the duration of oestrus, taking into account the weaning-to-oestrus interval, is helpful when establishing appropriate AI-schedules. However, as the length of oestrus varies within and between farms, different AI strategies should be established a priori. The development of bio-sensors for spontaneous ovulation will widen the use of AI with frozen-thawed frozen semen.

Animals↗

PubMed1990

Role of valence state and solubility of chromium compounds on induction of cytotoxicity, mutagenesis, and anchorage independence in diploid human fibroblasts.

We previously showed that carcinogenic nickel, arsenic, and chromium(VI) compounds induced anchorage independence (AI) in diploid human fibroblastic cells (HFC) derived from foreskins (K. A. Biedermann and J. R. Landolph, Cancer Res., 47: 3815-3823, 1987). To elucidate the role of the valence state of chromium and solubility of chromium compounds in inducing AI, we studied the ability of soluble and insoluble hexavalent [chromium(VI)] and trivalent [chromium(III)] chromium compounds to induce mutation and AI in HFC. Chromium(VI) compounds (PbCrO4, CaCrO4, Na2CrO4, and CrO3) were 1000-fold more cytotoxic to HFC (average 50% lethal dose 0.5 microM) than chromium(III) compounds (CrCl3, Cr2O3, Cr2S3; average 50% lethal dose 500 microM). However, equal concentrations (0.1-10.0 microM) of soluble or insoluble chromium compounds in either +6 or +3 valence states induced similar increases in frequencies of AI in HFC (100-200/10(5]. Chromium(VI)- and chromium(III)-induced AI was a stable phenotype. All soluble chromium(VI) and insoluble chromium(III) compounds studied induced mutation to 6-thioguanine resistance at cytotoxic concentrations in HFC. Insoluble PbCr(VI)O4 and a soluble form of Cr(III)Cl3 were inactive in this assay. Mutation induction by chromium(III) compounds only occurred at cytotoxic concentrations (100-1000 microM) 1000-fold greater than those concentrations of chromium(VI) compounds (0.25-1 microM) which were cytotoxic, mutagenic, and induced AI. Soluble hexavalent Na2(51)CrO4 was taken up facilely by cells at concentrations that induced cytotoxicity, mutation, and AI. At concentrations of 0.25-1.0 microM, which induced AI but were not cytotoxic or mutagenic, or concentrations of 1-1000 microM, which were cytotoxic and mutagenic, soluble trivalent 51CrCl3 was not taken up by cells. An insoluble form of CrCl3 was not taken up intracellularly but did avidly associate with cells over the concentration range 1 to 100 microM which induced AI, cytotoxicity, and mutagenicity. Therefore, both chromium(VI) and chromium(III) compounds induced genotoxic effects in human fibroblasts. Cellular uptake, cytotoxicity, mutagenicity, and AI induced by soluble chromium(VI) compounds all occurred at the low concentrations of 0.2 to 1.0 microM; hence mutagenicity and induction of AI may be coupled for soluble chromium(VI) compounds but not for insoluble PbCrO4, which induced AI but was not mutagenic. Cytotoxicity and mutagenicity of insoluble chromium(III) occurred at concentrations of 10-100 microM, but induction of AI occurred at concentrations of 0.1-10 microM, indicating that inductions of mutagenicity and AI were not coupled for chromium(III) compounds.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Adhesion↗

PubMed1983

The binding and processing of mannose-bovine serum albumin derivatives by rabbit alveolar macrophages. Effect of the sugar density.

Mammalian alveolar macrophages are known to bind, internalize, and degrade glycoconjugates containing terminal D-mannosyl residues such as bovine serum albumin modified with 2-imino-2-methoxyethyl 1-thio-alpha-D-mannopyranoside (Mann-AI-BSA) (Lee, Y. C., Stowell, C.P., and Krantz, M. J. (1976) Biochemistry 15, 3956-3963). In this report, the binding (2 degrees C) and initial uptake (37 degrees C) of Mann-AI-BSA (n = 5, 13, 24, and 43) by rabbit alveolar macrophages were examined. Man43-AI-BSA had about 400 times higher affinity (Kd = 2.0 nM) for the macrophage than the Man5-AI-BSA ligand (Kd = 820 nM) at 2 degrees C. Kinetic analysis of 125I-Man43-AI-BSA binding to macrophages at 2 degrees C yielded an association rate constant of 1.2 X 10(6) M-1 min-1 and a dissociation rate constant of 5.9 X 10(-3) min-1 (t1/2 = 117 min). The association rate constant at 37 degrees C was 2 orders of magnitude greater than at 2 degrees C. When the endocytotic process at 37 degrees C was analyzed by Michaelis-Menten-type kinetics, Man5-AI-BSA had a K uptake 20 times higher than that of Man43-AI-BSA (328 and 18 nM, respectively). The maximal uptake velocities at 37 degrees C were, however, very similar for all four Man-AI-BSA derivatives (62,600-83,000 molecules/cell/min). The rate constants for internalization and hydrolysis for 125I-Man43-AI-BSA and 125I-Man13-AI-BSA were determined using a steady state approach. The internalization rate constant for 125I-Man43-AI-BSA, 1.23 (+/- 0.20) min-1, was similar to that constant obtained for 125I-Man13-AI-BSA, 1.80 (+/- 0.67) min-1. The hydrolysis rate constants for the two ligands were also close, 7.4 (+/- 0.2) X 10(-2) and 9.2 (+/- 0.5) X 10(-2) min-1, for 125I-Man43-AI-BSA and 125I-Man13-AI-BSA, respectively.

Animals↗

PubMed2003

GABAergic and glutamatergic axons innervate the axon initial segment and organize GABA(A) receptor clusters of cultured hippocampal pyramidal cells.

We have studied gamma-aminobutyric acid (GABA)(A) receptor (GABA(A)R) clustering within the axon initial segment (AIS) in low-density cultures of hippocampal pyramidal cells following GABAergic and glutamatergic innervation of the AIS. Large, intensely fluorescent, and postsynaptic GABA(A)R clusters were present in the AIS. More than 95% of these clusters colocalized with presynaptic GABAergic or glutamatergic terminals, forming matched or mismatched synapses, respectively. Less than 5% of the GABA(A)R clusters of the AIS did not colocalize with GABAergic or glutamatergic terminals, suggesting that GABA(A)Rs normally do not form clusters unless the AIS received GABAergic or glutamatergic innervation. Few or no clusters of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) receptors or the postsynaptic density-95 protein (PSD-95) were found in the AIS, even when the AIS was innervated by glutamatergic axons. Glutamatergic innervation of the AIS that formed mismatched synapses with postsynaptic GABA(A)R clusters mainly occurred when the AIS did not receive GABAergic innervation. However, when the AIS was innervated by GABAergic axons, the formation of matched GABAergic synapses predominated and coincided with large reductions in both the density of glutamatergic terminals from the AIS and the mismatching of GABA(A)R clusters. A similar effect was observed at axo-dendritic synapses, where GABAergic innervation also led to a large decrease in mismatched GABA(A)R clusters and a smaller, but significant, decrease in glutamatergic terminal density in dendrites that received GABAergic innervation. We hypothesize that competition between GABAergic and glutamatergic innervation of the AIS in the intact hippocampus leads to the exclusive presence of GABAergic inhibitory synapses in the AIS of pyramidal cells.

Animals↗

PubMed2003

New acquisitions in the assessment of breath-by-breath alveolar gas transfer in humans.

We summarise recent results obtained in testing some of the algorithms utilised for estimating breath-by-breath (BB) alveolar O2 transfer (VO2A) in humans. VO2A is the difference of the O2 volume transferred at the mouth minus the alveolar O2 stores changes. These are given by the alveolar volume change at constant O2 fraction (FAiO2 DeltaVAi) plus the O2 alveolar fraction change at constant volume [V(Ai-1)(FAi-F(Ai-1))O2], where V(Ai-1) is the alveolar volume at the beginning of the breath i. All these quantities can be measured BB, with the exception of V(Ai-1), which is usually set equal to the subject's functional residual capacity (FRC) (Auchincloss algorithm, AU). Alternatively, the respiratory cycle can be defined as the time elapsing between two equal O2 fractions in two subsequent breaths (Grønlund algorithm, GR). In this case, FAiO2= F(Ai-1)O2 and the term V(Ai-1)(FAi-F(Ai-1))O2 disappears. BB alveolar gas transfer was first determined at rest and during exercise at steady-state. AU and GR showed the same accuracy in estimating alveolar gas transfer; however GR turned out to be significantly more precise than AU. Secondly, the effects of using different V(Ai-1) values in estimating the time constant of alveolar O2 uptake (VO2A) kinetics at the onset of 120 W step exercise were evaluated. VO2A was calculated by using GR and by using (in AU) V(Ai-1) values ranging from 0 to FRC +0.5 l. The time constant of the phase II kinetics (tau2) of VO2A increased linearly, with V(Ai-1) ranging from 36.6 s for V(Ai-1)=0 to 46.8 s for V(Ai-1)=FRC+0.5 l, whereas tau2 amounted to 34.3 s with GR. We concluded that, when using AU in estimating VO2A during step exercise transitions, the tau2 value obtained depends on the assumed value of V(Ai-1).

Algorithms↗

PubMed1991

Characterization of the enamel ultrastructure and mineral content in hypoplastic amelogenesis imperfecta.

Amelogenesis imperfecta (AI) comprises a diverse group of hereditary enamel disorders that are characterized by hypoplastic and in some cases hypomineralized defects. The specific biochemical abnormalities remain unknown for all AI types, making histologic and chemical analyses of affected dentitions essential for resolving the etiology of AI. The purpose of this investigation was to characterize the ultrastructure and mineral content of smooth hypoplastic AI enamel. The AI enamel showed no evidence of surface pitting and was uniformly reduced in thickness by approximately 60% compared with control enamel. Imbibition studies indicated that the AI enamel was generally porous. The first 30 microns of AI enamel adjacent to the dentinoenamel junction was translucent with poorly formed prisms. Abnormal prism structure was seen throughout the AI enamel. Amorphous, presumably organic material that may have been retained enamel protein was also seen. Although the crystallite widths were similar in both AI and normal enamel, the AI teeth showed areas where the crystallite order and continuity appeared disrupted. The mean mineral content was similar for all variables measured except sodium, which was significantly lower in the AI teeth. The calcium concentration was very low in the AI enamel directly adjacent to the dentinoenamel junction and showed a steeper concentration gradient moving from the dentin to the surface compared with control teeth. It may be concluded that the ameloblasts in smooth hypoplastic AI produce a tissue of reduced thickness, which is excessively porous and displays alterations in its ultrastructural organization.

Ameloblasts↗

PubMed1996

Apoptosis and downstaging after preoperative radiotherapy for muscle-invasive bladder cancer.

PURPOSE: To determine the relationship between pretreatment apoptosis levels and clinical-to-pathologic downstaging resulting from preoperative radiotherapy. METHODS AND MATERIALS: Between 1960-1983, 338 patients were dispositioned to receive preoperative radiotherapy 4-6 weeks prior to radical cystectomy for muscle-invasive transitional cell carcinoma of the bladder. Of these, adequate hematoxylin and eosin stained tissue sections for morphologic analysis of apoptosis were available in 158 patients. These patients were treated to a median dose of 50 Gy at 2 Gy per fraction. Median follow-up was 90 months. The apoptotic index (AI) was calculated from the ratio of the number of apoptotic cells divided by the total counted and multiplied by 100. A minimum of 500 cells were counted from each patient. RESULTS: The average AI for the whole group (n = 158) was 2.0 +/- 1.3 (+/- SD), with a median of 1.8. The association of AI to clinical stage was significant with AI averages of 1.8 for Stage T2 (n = 56), 1.9 for T3a (n = 51), and 2.4 for T3b (p = 0.038, Kendall Correlation). The relationship of AI to radiotherapy response also was significant with an average of 2.2 for those who were downstaged (n = 103), 1.9 for those in whom the stage remained unchanged (n = 20), and 1.7 for those who were upstaged (n = 35, p = 0.054, Kendall Correlation). The other significant correlations with AI were for the factors, grade, mitotic index, number of tumors, and gender. The AI was then categorized into three groups ( < or = 1, > 1, and < or = 3, and > 3) to examine the prognostic significance of this parameter. The distributions of patients by clinical stage, grade, mitotic index, number of tumors, radiotherapy response, and hemoglobin level were significantly associated with AI using this grouping. When the analysis of the distribution of patients by radiation response and AI was segregated by stage, a significant correlation was observed only for those with Stage T3b disease (p = 0.006); 93% of T3b patients with an AI > 3 were downstaged, while in 7% the stage remained unchanged and none were upstaged. The relationship of AI to 5-year actuarial patient outcome was investigated using several end points and although no significant correlations were observed, a trend was seen for improved survival when AI was > 3 (71% vs. 41%, p = 0.09) for Stage T3b patients. CONCLUSION: The AI correlated most strongly with radiotherapy response for patients with clinical stage T3b disease, the one subgroup of patients wherein preoperative radiotherapy is likely to be of the most benefit. Further investigation of pretreatment apoptosis levels as a marker of anticancer response is needed, especially for patients treated with chemotherapy and radiotherapy with the goal of bladder preservation.

Aged↗

PubMed1992

Obstructive sleep apnea subtypes by cluster analysis.

A sample of 84 adult male patients with obstructive sleep apnea (OSA) were classified by a cluster analysis on the basis of apnea index (AI) and body mass index (BMI). Demographic, cephalometric, tongue, soft palate, and upper airway-size data were evaluated for the two subgroups of OSA patients and for 18 control subjects. One OSA group consisted of 43 patients with a high AI and low BMI ratio, the other group was comprised of 41 patients with a low AI and high BMI ratio. The patients with a high AI and low BMI ratio had retruded mandibles with high mandibular plane angles and proclined lower incisors. The patients with a low AI and high BMI ratio had inferior hyoid bones and large soft palates. A multiple regression analysis was performed between AI (the dependent variable) and the other variables (independent variables) for each of the subgroups. In the patients with a high AI and low BMI ratio, a high AI was related to a large skeletal anteroposterior discrepancy, a steep mandibular plane, and an inferoanterior position of the hyoid bone. In the patients with a low AI and high BMI ratio, a high AI was related to a large tongue and a small upper airway. In both groups, BMI was the major contributor to AI. In conclusion, these two groups may represent distinct subgroups of OSA patients and provide some insight into the contribution of obesity to the pathogenesis of OSA. The patients with a high AI and low BMI ratio have a skeletal mismatch, whereas the patients with a low AI and high BMI have atypical soft tissue structures.

Body Mass Index↗

PubMed2006

Side effects of aromatase inhibitors versus tamoxifen: the patients' perspective.

BACKGROUND: Hormonal therapy is a mainstay in the management of estrogen receptor-positive (ER+) breast cancer. Tamoxifen (TAM) has been the drug widely used until the recent emergence of the aromatase inhibitors (AIs). Although AIs appear to be better tolerated than tamoxifen, they do have a different safety profile and these side effects have not been well characterized in community practice. We surveyed patients with ER+ breast cancers who received adjuvant hormonal therapy to determine how these medications impacted their quality of life and whether side effects or cost influenced decisions to continue therapy. METHODS: A mailed questionnaire and community cancer registry were used. RESULTS: Four hundred fifty-two of 902 surveys were returned for a 50% response rate. Eighty-two percent of respondents were placed on (adjuvant hormonal therapy) some form of estrogen-blocking therapy. Fifty-four percent of these were placed on tamoxifen and 46% on an AI. The most troublesome symptoms for tamoxifen and AI users, respectively, included hot flashes (35%/30%), weight gain (14%/15%), insomnia (17%/17%), and joint aches (12%/23%, P = .002). Thirty-nine percent of TAM users and 46% of AI users were taking medications to control their symptoms. Fifty percent of TAM users and 39% of AI users took vitamin E to help control hot flashes. Forty-two percent of TAM users versus 32% of AI users took Advil (Wyeth, Richmond, VA) for muscle/joint aches; 47.5% of AI users switched medication to improve symptoms as compared with only 37% of tamoxifen users (P = .015). The average cost of medications to control side effects for both tamoxifen and AI users was $67.36 per month. CONCLUSIONS: In our survey, both tamoxifen and AI users reported significant and different side effects. AI users suffered more frequently from musculoskeletal complaints, and more AI users switched therapy. Both AI and tamoxifen users used adjunctive medications for symptom control. In both groups, a large number used vitamin E to help hot flashes despite weak evidence to support its effectiveness in this setting. Cost of therapy and symptom control was not a major barrier to care.

Antineoplastic Agents, Hormonal↗

PubMed2005

Vasodilatation vs. immunotherapy to prevent delayed graft function: delayed graft function as an indication of immune activation.

Delayed renal allograft function (DGF) is a factor for acute rejection and chronic allograft nephropathy. Cold ischemia time (CIT) is associated with an increased in DGF. Twenty patients receiving allografts with CIT>12 were enrolled in a double-blinded, randomized (1:1), placebo-controlled study to assess vasodilatation with fenoldopam (Abbott; dopamine-1 receptor agonist) on DGF. Fenoldopam infusion began at arterial anastomosis at 0.025 microg/kg/min and titrated to 0.1 microg/kg/min continued for 48 h postop (PO). Immunosuppression included steriods, MMF, and calcinurin inhibitors begun 36 h PO. Antibody induction (AI) using antithymocyte globulin (rabbit) (AT-G(r); Sangstat) was added halfway through the study to African-Americans and for PRA>40%. The need for dialysis, cumulative urine output (UOP), and creatinine (Cr) at PO day 7, 14, and 30 were compared. Eighteen patients completed the study drug infusion. Demographics of groups were not different. There was no difference between fenoldopam and controls for dialysis, UOP at 48 and 72 h, or Cr at 7, 14, or 30 days. There was a difference in UOP when AI (n=7) was compared to non-AI (n=11). At 48 h non-AI UOP 4796+/-3284 ml compared to AI UOP 8960+/-5130 ml (p=0.050). At 72 h, non-AI patients had UOP of 6824+/-4547 ml compared to AI patients with UOP of 12196+/-5868 ml (p=0.044). There was a trend to a lower Cr at day 7 for AI 2.7+/-2.1mg/dl compared to 4.9+/-3.0 mg/dl in non-AI (p=0.11). There was no difference in dialysis or Cr at day 14 and 30 between the AI and non-AI patients. AI with AT-G(r) significantly increases UOP in allografts with CIT>12 h, whereas vasodilatation did not. Therapy for DGF may include AT-G(r) AI.

Adult↗

PubMed1996

Increased arterial inflow in extremities with chronic venous insufficiency: an important and unappreciated hemodynamic parameter.

BACKGROUND: The purpose of this study was to evaluate and analyze arterial inflow (AI) in lower extremities of patients with symptoms of chronic venous insufficiency (CVI) and of members of a healthy control group. METHODS: Foot mercury-in-silicon strain-gauge plethysmography was used to measure AI, venous reflux, and muscle pump efficiency in 388 extremities of 194 patients with symptoms of CVI. Severe stage III symptoms (Society for Vascular Surgery/International Society for Cardiovascular Surgery classification) were present in 84 extremities, moderate stage II symptoms were present in 81 extremities, and mild stage I symptoms were present in 158 extremities. No symptoms, stage 0, were found in 65 contralateral extremities of patients with unilateral symptoms. Identical parameters were measured in 70 extremities of 35 healthy subjects in a control group. AI in each staged group was compared with that of the control group and with that of the other groups with symptoms with the use of Kruskall-Wallis analysis of multiple variances. RESULTS: The mean AI (+/-SD) in milliliters per 100 ml of foot tissue per minute in the extremities in the control group was 0.82 +/- 0.48. In the extremities without symptoms, contralateral to those with symptoms in patients with unilateral disease, the AI was 1.24 +/- 0.88. In extremities with mild symptoms the AI was 1.54 +/- 1.20, in extremities with moderate symptoms it was 2.88 +/- 1.70, and in extremities with severe symptoms it was 6.25 +/- 4.91. The AI was significantly increased in all extremities of patients with CVI (stages 0 to III) when compared with that of patients in the control group. Extremities with stage II and III disease had significantly higher AI than did extremities with stage 0 and stage I disease. The difference in AI between extremities with stage 0 and I disease was not statistically significant, and no significant difference in AI was seen between extremities with stage II and III disease. CONCLUSIONS: When plethysmographic methods are used to evaluate extremities with CVI, high AI, if not considered, can overrepresent the true magnitude of reflux. High AI may indicate presence of primary anatomic arterioventricular fistulas, or it may be the consequence of inflammatory changes and secondary functional arterioventricular shunting. Increased AI in contralateral extremities with no symptoms may point to the role of high flow in the pathogenesis of CVI. Clarification of this question requires further investigation.

Adult↗

PubMed1999

Quorum sensing, gene expression, and Pseudomonas biofilms.

Quorum sensing has been shown to be important for the development of a normal P. aeruginosa biofilm, and it follows that other microorganisms may employ a similar mechanism in the development of mature biofilms. To methods for detecting the presence of AI activity in biofilms are presented that employ an AI-responsive reporter strain harboring a lacZ fusion. Method 1 involves detection of AI activity in crude biofilms, whereas Method 2 employs an AI purification procedure. By using multiple indicator strains activated by AIs various acyl chain lengths, a wide range of AI molecules can be detected. Chromosomal knockout mutants are extremely useful for examining the contribution of a given gene to a specific phenotype. For quorum-sensing gene expression studies, mutants deficient in the production of AI offer more versatility than R-protein mutants. The main advantage of the AI mutants is that they can be complemented by either the AI synthase gene or the AI itself. Complementation with the AI circumvents having to grow the cells in the presence of antibiotics and allows experimental parameters such as AI concentration and time of addition to be manipulated easily. Finally, three reporter systems suitable for monitoring gene expression in P. aeruginosa biofilms are summarized in T Table II. The choice of reporter fusion depends mainly on whether in vivo analysis is required, whether temporal gene expression is to be examined, and the availability of equipment. In the case of P. aeruginosa, expression of quorum-sensing genes can be monitored either directly, by examining fusions of the R genes or AI synthase genes, or indirectly, by analyzing expression of genes controlled by these quorum-sensing systems.

Bacterial Adhesion↗

PubMed1986

Removal of aluminum during hemodialysis: effect of different dialyzer membranes.

Aluminum toxicity is now widely recognized as a major cause of morbidity in patients on maintenance hemodialysis. Desferrioxamine (DFO) chelation therapy has been suggested as a method of AI removal in such patients, though the most appropriate treatment schedule is yet to be established. In the present study, AI removal following DFO infusion was evaluated using two different dialyzer membranes to test the hypothesis that polyacrilonitrile (PAN) membranes permit better AI clearance. All patients studied had significantly elevated plasma AI concentrations (1.22 to 9.45 mumol/L; normal less than 0.56 mumol/L). Plasma AI did not correlate with estimated total AI intake. During hemodialysis with a cuprophane membrane, AI clearance ranged from 33.5 to 42.1 mL/min. Total AI removal was 192.2 +/- 90.4 mumol during cuprophane dialysis. During hemodialysis with a PAN membrane, AI clearance ranged from 35.7 to 54 mL/min. Total AI removal was 154.2 to 93.9 mumol during PAN dialysis. The differences in AI clearance and total AI removal were not statistically significant. It is concluded that use of a PAN membrane does not significantly enhance DFO-AI clearance.

Acrylic Resins↗

PubMed2003

Physical activity reduces genetic susceptibility to increased central systolic pressure augmentation: a study of female twins.

OBJECTIVES: We sought to examine associations between the augmentation index (AI) and metabolic, adiposity, and lifestyle factors, independent of genetic influences, and to determine whether gene-environment interactions modulate these relationships. BACKGROUND: Reported associations between AI, an index of systemic arterial stiffness, and metabolic, adiposity, and lifestyle factors remain contradictory. The modulating effect of genetic risk is unknown. METHODS: We studied 684 female twins (age 18 to 71 years); AI was derived from the pressure waveform measured at the radial artery by applanation tonometry. Percentage of total body fat (TBF) and percentage of central abdominal fat (CAF) were assessed by dual-energy X-ray absorptiometry. RESULTS: In univariate analysis, age-adjusted AI was significantly associated with fasting triglyceride levels (r = 0.1, P = 0.03), apolipoprotein-B/A1 (r = 0.1, P = 0.04), percentage of TBF (r = 0.11, P = 0.006), and percentage of CAF (r = 0.11, P = 0.004). In co-twin case-control (monozygotic twin) analysis, a 3.1% absolute within-pair difference in percentage of CAF accounted for a 6% within-pair difference in AI, independent of genetic effects. Smokers and subjects with alcohol intakes >15 U/week had higher AI than nonsmokers (p = 0.01) and nondrinkers (p = 0.02), respectively. Forty percent of the variance in AI was explained by age, central mean arterial pressure, heart rate, height, percentage of CAF, and smoking. In gene-environment interaction analysis, subjects at high genetic risk of increased AI participating in regular leisure-time physical activity had AI values similar to low genetic risk subjects. CONCLUSIONS: Central abdominal adiposity is a significant determinant of AI in female twins, independent of hemodynamic, lifestyle, and, importantly, genetic effects. Smoking is associated with increased AI, even after controlling for abdominal obesity and other AI determinants. Physical activity reduces genetic predisposition to increased AI.

Adolescent↗

PubMed2002

Expression of the liver form of arginase in erythrocytes.

Arginase I (AI) has a critical function in mammalian liver as the final enzyme in the urea cycle responsible for the disposal of ammonia from protein catabolism. AI is also expressed in various extrahepatic tissues and may play a role in regulating arginine levels and in providing ornithine for biosynthetic reactions that generate various critical intermediary metabolites such as glutamate, glutamine, GABA, agmatine, polyamines, creatine, proline, and nitric oxide. AI is expressed in red blood cells (RBCs) only in humans and certain higher primates. Macaca fascicularis has been identified as an evolutionary transition species in which RBC-AI expression is co-dominantly regulated. The M. fascicularis AI gene was analyzed to understand AI expression in erythrocytes. Erythroid progenitor cells [nucleated red blood cells (nRBCs)] isolated from cord blood were utilized to demonstrate AI expression by immunocytochemical staining using anti-AI antibody. Introduction of EGFP reporter vectors into nRBC showed that the proximal 1.2 kbp upstream of the AI gene is sufficient for AI expression. Expression of a second arginase isoform, AII, in nRBCs was discovered by cDNA profiling. This contrasts with mature fetal or adult RBCs which contain only the AI protein. In addition, an alternatively spliced AI (AI(')) variant was observed from erythroid mRNA analysis with an alternative splice acceptor site located within intron 2, causing the insertion of eight additional amino acids yet retaining significant enzymatic activity.

Alternative Splicing↗

PubMed1997

Tertiary and quaternary structures of 0.19 alpha-amylase inhibitor from wheat kernel determined by X-ray analysis at 2.06 A resolution.

The crystal structure of 0.19 alpha-amylase inhibitor (0.19 AI) from wheat kernel was determined by the multiple-isomorphous replacement method coupled with density modification and noncrystallographic symmetry averaging and then refined by simulated annealing using diffraction data to 2.06 A resolution (R = 18.7%, free R = 22.3%). The asymmetric unit has four molecules of 0.19 AI, each comprised of 124 amino acid residues. Electron density for residues 1-4 and 69-77 is absent in all subunits, probably because of the intrinsic flexibility of these segments. Each subunit has four major alpha-helices and one one-turn helix which are arranged in the up-and-down manner, maintaining the favorable packing modes of the alpha-helices. 0.19 AI, however, has two short antiparallel beta-strands. All 10 cysteine residues in 0.19 AI form disulfide bonds (C6-C52, C20-C41, C28-C83, C42-C99, and C54-C115), consistent with the assignments made biochemically for 0.28 AI from wheat kernel and by NMR analysis of the bifunctional alpha-amylase/trypsin inhibitor from ragi seeds (RBI). The disulfide bond patterns in these AIs are similar to those in the hydrophobic protein from soybean (HPS), which lack only the bond corresponding to C28-C83 in 0.19 AI. Extensive interactions occurred between particular pairs of 0.19 AI subunits, mainly involving hydrophobic residues. Comparisons of the structures of 0.19 AI, RBI, and HPS showed that the arrangements of the major alpha-helices are similar but the conformations of the remaining residues differ markedly. The present X-ray analysis for 0.19 AI and the NMR analysis for RBI suggest that all the AIs in this family have a common fold. The alpha-amylase binding site is discussed on the basis of the tertiary and quaternary structures of 0.19 AI together with biochemical and spectroscopic data for AIs.

Amino Acid Sequence↗

PubMed2003

Evaluation of two carrier protein-angiotensin I conjugate vaccines to assess their future potential to control high blood pressure (hypertension) in man.

AIMS: We aim to modulate the renin-angiotensin system (RAS) by active immunization against angiotensin I hormone (AI), potentially providing a novel conjugate vaccine treatment for hypertension in man. METHODS: Immunization studies in rat and human subjects compare the effectiveness of tetanus toxoid (TT) and keyhole limpet haemocyanin (KLH) vaccines for immunotherapy following conjugation with an AI peptide analogue (AI). Cardiovascular responses were assessed in immunized rats and human subjects (two-dose trial only), following increasing i.v. infusions of either AI or angiotensin II hormone (AII). RESULTS: The AI-TT and AI-KLH conjugate vaccines induced an equivalent immune response, and inhibition of the pressor effects to exogenous AI in rats. Single-dose clinical trials with both conjugate vaccines only resulted in an immune response to the KLH carrier protein. A two-dose clinical trial of AI-KLH conjugate vaccine resulted in a significant immune response to AI. A shift in diastolic blood pressure (DBP) dose-response was demonstrated following challenge with AI and AII for the study volunteer showing the largest anti-AI IgG induction. CONCLUSION: KLH was shown to be a suitable alternative to TT as a carrier protein for AI, thus supporting continued evaluation of our AI-KLH conjugate vaccine for treatment of hypertension in man.

Adolescent↗

PubMed2001

The LuxS family of bacterial autoinducers: biosynthesis of a novel quorum-sensing signal molecule.

Many bacteria control gene expression in response to cell population density, and this phenomenon is called quorum sensing. In Gram-negative bacteria, quorum sensing typically involves the production, release and detection of acylated homoserine lactone signalling molecules called autoinducers. Vibrio harveyi, a Gram-negative bioluminescent marine bacterium, regulates light production in response to two distinct autoinducers (AI-1 and AI-2). AI-1 is a homoserine lactone. The structure of AI-2 is not known. We have suggested previously that V. harveyi uses AI-1 for intraspecies communication and AI-2 for interspecies communication. Consistent with this idea, we have shown that many species of Gram-negative and Gram-positive bacteria produce AI-2 and, in every case, production of AI-2 is dependent on the function encoded by the luxS gene. We show here that LuxS is the AI-2 synthase and that AI-2 is produced from S-adenosylmethionine in three enzymatic steps. The substrate for LuxS is S-ribosylhomocysteine, which is cleaved to form two products, one of which is homocysteine, and the other is AI-2. In this report, we also provide evidence that the biosynthetic pathway and biochemical intermediates in AI-2 biosynthesis are identical in Escherichia coli, Salmonella typhimurium, V. harveyi, Vibrio cholerae and Enterococcus faecalis. This result suggests that, unlike quorum sensing via the family of related homoserine lactone autoinducers, AI-2 is a unique, 'universal' signal that could be used by a variety of bacteria for communication among and between species.

4-Butyrolactone↗