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PubMed2006

Insights into the retention mechanism on an octadecylsiloxane-bonded silica stationary phase (HyPURITY C18) in reversed-phase liquid chromatography.

Plots of the retention factor against mobile phase composition were used to organize a varied group of solutes into three categories according to their retention mechanism on an octadecylsiloxane-bonded silica stationary phase HyPURITY C18 with methanol-water and acetonitrile-water mobile phase compositions containing 10-70% (v/v) organic solvent. The solutes in category 1 could be fit to a general retention model, Eq. (2), and exhibited normal retention behavior for the full composition range. The solutes in category 2 exhibited normal retention behavior at high organic solvent composition with a discontinuity at low organic solvent compositions. The solutes in category 3 exhibited a pronounced step or plateau in the middle region of the retention plots with a retention mechanism similar to category 1 solutes at mobile phase compositions after the discontinuity and a different retention mechanism before the discontinuity. Selecting solutes and appropriate composition ranges from the three categories where a single retention mechanism was operative allowed modeling of the experimental retention factors using the solvation parameter model. These models were then used to predict retention factors for solutes not included in the models. The overwhelming number of residual values [log k (experimental) - log k (model predicted)] were negative and could be explained by contributions from steric repulsion, defined as the inability of the solute to insert itself fully into the stationary phase because of its bulkiness (i.e., volume and/or shape). Steric repulsion is shown to strongly depend on the mobile phase composition and was more significant for mobile phases with a low volume fraction of organic solvent in general and for mobile phases containing methanol rather than acetonitrile. For mobile phases containing less than about 20 % (v/v) organic solvent the mobile phase was unable to completely wet the stationary phase resulting in a significant change in the phase ratio and for acetonitrile (but less so methanol) changes in the solvation environment indicated by a discontinuity in the system maps.

Acetonitriles↗

PubMed1989

Correlation of protein retention times in reversed-phase chromatography with polypeptide chain length and hydrophobicity.

The use of amino acid retention or hydrophobicity coefficients for the prediction of peptide retention time behaviour on hydrophobic stationary phases is based on the premise that amino acid composition is the major factor affecting peptide retention in reversed-phase chromatography. Although this assumption holds up well enough for small peptides (up to ca. 15 residues), it is now recognized that polypeptide chain length must be taken into account when attempting to equate retention time behaviour of larger peptides and proteins with their overall hydrophobicity. In the present study, we have examined the reversed-phase retention behaviour of 19 proteins of known sequence on stationary phases of varying hydrophobicity and ligand density. From the observed protein retention behaviour on C4, C8 and C18 stationary phases under gradient elution conditions, we have been able to correlate the observed retention times of proteins ranging in molecular weight from 3500 to 32,000 dalton and in chain length from 30 to 300 residues with their overall hydrophobicity (based on retention parameters derived from small peptides) and the number of residues in the polypeptide chain. The retention behaviour of the proteins on the C4, C8 and C18 columns was also compared to that obtained on supports containing lower ligand densities (phenyl ligands). The maintenance of native or partially folded protein conformation on the phenyl columns, resulting in lower retention times than would be expected for fully denatured proteins, underlined the importance of efficient protein denaturation for satisfactory correlation of protein retention times with protein hydrophobicity. In addition, the effectiveness of increasing temperature and/or ligand density of the stationary phase in denaturing proteins was also demonstrated.

Chromatography, High Pressure Liquid↗

PubMed1986

Relationship between isocratic and gradient retention times in the high-performance ion-exchange chromatography of proteins. Theory and experiment.

Using isocratic retention parameters, the gradient elution retention time for several proteins has been calculated. The gradient retention time calculation is based on fitting the isocratic retention data to an equation of the form: log k' = m log (1/[Ca2+]) + log K and on applying well-established principles of gradient elution. A good correlation between the observed and calculated retention times for several test proteins was obtained at various total gradient times and column flow-rates. Conversely, isocratic retention parameters characterizing protein retention can be calculated from gradient elution retention data. However, even with retention data of high quality, small errors are amplified by the log-log nature of the ion-exchange isocratic retention model employed. Based on the close correlation between predicted and observed gradient retention times, no evidence for protein denaturation resulting from immobilization of the protein at high initial k' values at or near the column inlet was observed.

Buffers↗

PubMed2003

Fluid retention after initiation of thiazolidinedione therapy in diabetic patients with established chronic heart failure.

OBJECTIVES: We sought to define the characteristics of fluid retention after thiazolidinedione (TZD) initiation in patients with established heart failure (HF). BACKGROUND: Fluid retention associated with the use of TZD is commonly attributed to exacerbation of HF, which has led to the proscription of these potentially useful agents in patients with chronic HF. METHODS: We examined 111 consecutive diabetic patients with chronic systolic HF who were treated with TZD from January 1999 to June 2001. A retrospective chart review was performed to determine the incidence of fluid retention in this cohort. Physical signs of fluid retention were compared between TZD users and an age- and gender-matched control group of diabetic, non-TZD users with chronic HF who had fluid retention. Baseline clinical and echocardiographic data were compared between TZD users with and without fluid retention. RESULTS: Nineteen TZD users (17.1%) developed fluid retention, which reversed after drug withdrawal and presented predominantly as peripheral and not central edema. Comparing patients in the upper and lower tertiles of weight gain, more female patients and insulin users developed TZD-related fluid retention. However, there were no differences in the baseline New York Heart Association functional class or echocardiographic severity of cardiac dysfunction. CONCLUSIONS: Although fluid retention after treatment with TZD in diabetic patients with chronic systolic HF occurs, the mechanism is undefined. Fluid retention related to TZD tends to be peripheral and is usually reversible after drug withdrawal. No direct association between the risk of fluid retention and the baseline degree of severity of HF was observed.

Adult↗

PubMed1980

Prediction of peptide retention times in high-pressure liquid chromatography on the basis of amino acid composition.

Analysis of peptides by reverse-phase high-pressure liquid chromatography would be simplified if retention times could be predicted by summing the contribution to retention of each of the peptide's amino acid side chains. This paper describes the derivation of values ("retention coefficients") that represent the contribution to retention of each of the common amino acids and end groups. Peptide retention times were determined on a Bio-Rad "ODS" column at room temperature with a linear gradient from 0.1 M NaclO(4), pH 7.4 or 2.1, at 0 min to 60% acetonitrile/0.1 M NaclO(4) at 80 min. The NaclO(4), a chaotropic agent, was added to improve peak shape and to minimize conformational effects. Retention coefficients for the amino acids were computed by using a Hewlett-Packard 9815A calculator programmed to change the retention coefficients for all amino acids sequentially to obtain a maximum correlation between actual and predicted retention times. Correlations of 0.999 at pH 7.4 and 0.997 at pH 2.1 were obtained for 25 peptides including glucagon, oxytocin, [Met]enkephalin, neurotensin, and somatostatin. This high degree of correlation suggests that, for peptides containing up to 20 residues, retention is primarily due to partition processes that involve all the residues. Although steric or conformational factors do have some effect on retention, the data suggest that under the above chromatographic conditions the retention of peptides containing up to 20 residues can be predicted solely on the basis of their amino acid composition. This possibility was tested by using data taken from the literature.

Amino Acid Sequence↗

PubMed2002

Mechanisms for sickle red blood cell retention in choroid.

PURPOSE: Although sickle (SS) red cell-mediated vaso-occlusion in retina and resultant retinopathy is well documented, the effects of SS red cells on choroidal vasculature are poorly understood. The intent of this study was to determine, using a rat model, the conditions under which retention of sickle erythrocytes in choroid occur and if that retention can be inhibited. METHODS: Sickle red cells were density separated into high density (SS4) or normal density, reticulocyte-enriched fractions (SS2). Red cells were labeled with FITC and administered IV to anesthetized Sprague Dawley rats. Rats were made either hypoxic or were given TNF-alpha intraperitoneally 5 hours before intravenous administration of red cells. Five minutes after administration of red cells, rats were exsanguinated, the retinas removed, and choroids prepared as flatmounts. The number of red cells retained in five high power fields of choroid was then determined. In other experiments, SS red cells were preincubated with the cyclic peptide TBC772 [inhibits binding of alpha4beta1 (VLA-4) and alpha4beta7 to their ligands], a control peptide TBC1194, or a VLA-4 neutralizing antibody before administration to the rat or antibodies against VLA-4 ligands were delivered IV before administration of SS red cells. RESULTS: Hypoxic conditions before administration of SS red cells significantly stimulated retention of SS4 cells (P = 0.0003), but did not significantly increase retention of SS2 cells. Administration of TNF-alpha significantly increased retention of all types of SS red cells (P < 0.001). Preincubation of cells with anti-VLA-4 or TBC 772 inhibited retention of SS red cells in choriocapillaris of TNF-alpha-treated rats (P < 0.0001). Complete inhibition of cytokine-stimulated retention was also accomplished by IV administration of monoclonal antibodies against fibronectin or its CS-1 domain, a ligand for VLA-4. CONCLUSIONS: The mechanisms for retention of SS red cells in retina and choroid appear identical: hypoxia-mediated retention of dense red cells and adherence of red cells in reticulocyte-rich fractions after cytokine stimulation. TNF-alpha-stimulated retention of SS red cells in choroid appears to be mediated by VLA-4, presumably on the surface of some reticulocytes. This increased retention was inhibited by a VLA-4 antagonist (TBC772), a VLA-4 neutralizing antibody or by blocking one of VLA-4's ligands, the CS-1 portion of fibronectin.

Anemia, Sickle Cell↗

PubMed2003

Viability of and plasmid retention in frozen recombinant Escherichia coli over time: a ten-year prospective study.

The long-term viability and plasmid retention of recombinant Escherichia coli strains were investigated by real-time testing of master cell banks (MCBs) stored at the Roche Molecular Systems Culture Collection (RMSCC). MCBs at the RMSCC were cryogenically frozen and stored at -80 degrees C for long-term preservation. At regular intervals during a period of 5 to more than 10 years, representative cryovials of each MCB were tested for viability and plasmid retention. Plasmid retention and viability for all 30 MCBs were stable over time. Twenty-seven MCBs maintained high levels of plasmid retention (at or near 100%), while three MCBs showed lower plasmid retention rates (ranging from 13.9 to 96.5%) that were consistent over time. New MCBs with high plasmid retention were created from two of the MCBs with lower plasmid retention by selective pressure with high levels of antibiotics. These new MCBs have shown stable viability and high plasmid retention over the first 5 months of storage. In conclusion, this study shows that properly selected, frozen and stored MCBs retain viability and maintain plasmid retention over time. Moreover, it is possible to recover cultures with high plasmid retention from MCBs with low plasmid retention by selecting clones grown in the presence of high levels of antibiotics.

Bacteriological Techniques↗

PubMed2001

Outcome of polyester cuff retention following traction removal of tunneled central venous catheters.

PURPOSE: To elucidate the factors that contribute to cuff retention during traction removal of tunneled catheters, as well as to determine the risk of complication associated with polyester cuff retention. MATERIALS AND METHODS: A total of 428 tunneled, cuffed catheters were removed with traction and local anesthesia. Polyester cuff retention was recorded when it occurred, and the effects of cuff retention were determined at a mean follow-up of 250 days. Statistical analysis was performed to determine the variables influencing cuff retention. RESULTS: Traction removal was successful in 428 (100%) patients. Of 428 catheters removed, 41 (10%) cuffs were retained. Silicone 10-F double-lumen and 9.6-F single-lumen catheters had a higher rate of cuff retention (27 [32%] of 84 and nine [39%] of 23, respectively) than did the split-tip polyurethane hemodialysis catheter (two [1%] of 196; P <.001). Cuff retention rates among other catheter types compared with that of the polyurethane catheter were not significantly different. Duration of catheter dwell did not significantly influence cuff retention. Of 41 retained cuffs, three required removal with cutdown for cuff migration to the exit site, which inhibited healing (n = 1); for suspected infection (n = 1); or for cosmetic purposes as requested by the patient (n = 1). The remaining patients had no complications associated with cuff retention. CONCLUSION: Traction removal of smaller-bore silicone catheters is more likely to result in cuff retention than removal of larger silicone and polyurethane catheters, and cuff retention is usually inconsequential.

Catheterization, Central Venous↗

PubMedDate not supplied

Role of active floodplains for nutrient retention in the river Rhine.

We evaluated the importance of floodplains for nutrient retention in two distributaries of the river Rhine (Waal and IJssel) by monitoring N and P retention in a body of water during downstream transport. We hypothesized that (i) retention of P is much larger than retention of N and (ii) nutrient retention increases with an increasing amount of the discharge flowing through floodplains (QF). The second hypothesis was tested by comparing retention between the rivers Waal (low QF) and IJssel (high QF), as well as at different discharges. Total nitrogen (TN) did not decrease significantly during downstream transport in both rivers, whereas 20 to 45% of total phosphorus (TP) disappeared during transport in the river IJssel. This difference between N and P retention-supporting the first hypothesis-was probably caused by differences in sedimentation through a much lower proportion of N adsorbed to particles than of P (2-3% of N vs. 50-70% of P). Phosphorus retention was only observed in the IJssel and not in the Waal, and absolute P retention (g P s(-1) km(-1)) in the IJssel increased with increasing QF. The second hypothesis was, nevertheless, not fully supported, because the percentage P retention (% of P load) decreased (instead of increased) with increasing QF. The percentage P retention increased with decreasing river depth and flow velocity; it seemed related to the efficiency of sediment trapping.

Environmental Monitoring↗

PubMed1992

Mechanisms of lipopolysaccharide-induced neutrophil retention. Relative contributions of adhesive and cellular mechanical properties.

Intravascular LPS rapidly induces neutrophil sequestration in pulmonary capillaries by mechanisms that, although currently unknown, must take into account the size difference between the neutrophil and capillary diameter. To determine whether LPS alters neutrophil stiffness, and hence the ability of neutrophils to traverse capillaries, neutrophil passage through pulmonary capillaries was modeled by passage through filters with 6.5-microns pores. LPS increased retention in the pores in a concentration-dependent fashion that required the presence of heat-inactivated platelet-poor plasma, and was evident as early as 10 min after stimulation. The effect of LPS on the structural properties of the neutrophil was then studied. LPS induced f-actin reorganization in neutrophils in the presence of plasma. Disruption of actin organization and assembly with cytochalasin D completely inhibited early LPS-induced retention and attenuated retention at later timepoints, indicating that LPS-stimulated retention depends on filament organization. LPS-induced actin assembly and retention were abrogated by an antibody directed against CD14, a putative LPS receptor. CD18-dependent adherence of neutrophils contributed significantly to retention only at later timepoints with no significant contribution to retention at 20 min as determined by inhibition of adherence with the mAb 60.3. Morphometric assessment of neutrophil accumulation in the lungs of rabbits given 1 microgram LPS showed a marked increase in apparent neutrophil number, which was unaltered by antibodies to CD18, suggesting that mechanisms other than adhesion may account for accumulation in vivo. Direct measurements showed that neutrophil stiffness increased with exposure to LPS in a fashion similar to LPS-induced retention and actin organization. Pretreatment of neutrophils with cytochalasin D attenuated the increased stiffness. These data suggest that reorganization of filamentous-actin induced by LPS leads to cell stiffening and retention in capillary-sized pores. Although the organization of f-actin continues to be important in retention at later time points, adherence of cells also contributes significantly to cell retention. The changes in mechanical properties of the neutrophil may be important in the sequestration of neutrophils in pulmonary capillaries noted in endotoxemia.

Actin Cytoskeleton↗

PubMedDate not supplied

Compomer as a pit and fissure sealant: effectiveness and retention after 24 months.

PURPOSE: The aim of this study was to evaluate the effectiveness and retention of occlusal sealing using FluroShield or Compoglass. METHODS: The sample consisted of 57 children aged 7 to 9 years who had 4 sound, fully erupted, first permanent molars (total=228 teeth). Both materials were applied on contralateral teeth in a split-mouth design in 2 groups: (1) FluroShield--left upper molar and right lower molar; (2) Compoglass--right upper molar and left lower molar. The materials were applied under cotton roll isolation by the same operator according to the manufacturers' instructions. The evaluations were carried out at 6, 12, and 24 months. The data were subjected to the G2 (likelihood ratio chi-square test; P<.05). RESULTS: At the 6-month evaluation, Compoglass showed 60% total retention, 23% partial retention, and 17% total loss. FluroShield showed 53% total retention, 31% partial retention, and 16% total loss. At the 12-month recall, Compoglass and FluroShield, respectively, showed 39% and 43% total retention, 38% and 33% partial retention, and 24% and 25% total loss. At the 24-month evaluation, there was a reduction of 56% of the initial sample numbers (32/57), with 22% and 20% having total retention, 52% and 48% partial retention, and 26% and 32% total loss, respectively, for Compoglass and FluroShield. There was no significant statistical difference between the retention of both materials studied. There was no new caries formation during the evaluation period. CONCLUSION: It could be concluded that both materials effectively prevented caries in occlusal surfaces during the follow-up period, although both showed a low retention rates.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1991

[Retention of composite inlays in enamel-dentin cavities].

The retention of composite inlays depends on acid-etching of marginal enamel of the preparation. In many cases, only little marginal enamel is available, making loss of retention a liability. The present study evaluated the retention of three brands of composite inlays under various conditions. Inlays were fabricated and cemented in standardized enamel/dentin cavities prepared in extracted human teeth. The force necessary to extract a cemented inlay was used to express the retention of the inlay. The effects of thermocycling and choice of dentin-bonding agent on inlay retention were also determined. Inlays made of Estilux posterior C VS were more retentive than inlays of either Brilliant Dentin or SR-Isosit. The latter two products were found to provide similar retentive strengths. The retention of Estilux posterior C VS and SR-isosit inlays declined when samples were thermocycled. Treatment with Gluma increased retention of inlays, resulting in retentive strengths of the same magnitude for all three inlay systems. The choice of dentin-bonding agent was found to affect composite inlay retention to a greater extent than the choice of either composite brand, mode of inlay curing, or effect of thermocycling.

Acrylic Resins↗

PubMed1990

Interim luting agents, composite core surface hardness and retention of interim and final restorations.

This study compared the effects of ZOE interim cement on the retention of interim acrylic and final cast crowns (cemented with zinc phosphate) over cores of current conventional and hybrid composite resin formulae, and a non-eugenol interim cement (NOG) and a calcium hydroxide liner (CaOH2) on interim and final retention values over hybrid cores. Results were compared to retention of cast crowns over amalgam cores. Retention was measured with an Instron Testing Machine. Location of cement failure during separation was recorded. Surface hardness of each group was compared. Retention of cast crowns cemented with zinc phosphate over amalgam cores was significantly higher than that of any of the resin core groups (ANOVA, P less than 0.05, Sheffe Contrast). There was no significant difference in final casting retention cemented over hybrid or conventional resin cores exposed to ZOE (13.625 vs 14.125 Kg). Final casting retention differences were not significant between the three interim cement groups. Final retention of all groups exposed to an interim luting agent were significantly less than the composite control groups. The use of CaOH, as an interim luting agent for acrylic crowns over hybrid cores compared to ZOE or NOG, should afford significantly greater retention with no adverse effect on the retention of the final casting. While the surface hardness of both types of composite resin was adversely affected by exposure to interim luting agents as compared to controls, there was no correlation between final casting retention values and surface hardness of polished composite. The interim cements invariably failed at the interim acrylic crown interface while the zinc phosphate cement failed at the core interface.

Acrylic Resins↗

PubMed1987

Effect of monoclonal antibodies against von Willebrand factor and platelet glycoproteins IIb/IIIa on the platelet retention test.

The platelet retention test provides a measure of the number of platelets retained in a column of glass beads and is one of the few in vitro platelet function tests that is abnormal in von Willebrand's disease (vWd). In a two-stage test, 1 mL of blood (designated A) was passed through the column, followed by 5 mL of isotonic saline and then 5 mL of blood (B) in which platelet retention was measured. With normal blood as A and B, retention is very high in all 5 mL of blood B. In the first stage, platelets adhere to the glass beads; this requires fibrinogen but not von Willebrand factor (vWf). The platelet-platelet adhesion in the second stage requires vWf, is dependent on release of ADP, and fails to occur if thrombasthenic platelets are tested. Retention was normal when blood from a patient with afibrinogenemia was used as blood B. We have now used monoclonal antibodies to elucidate further the mechanism of platelet retention. Five antibodies to different epitopes on vWf essentially abolished retention in the one-stage test and in the second stage of the two-stage test, but had no effect on the first stage. Thus, the entire vWf molecule must be free of antibody to function in the platelet-platelet adhesion of the second stage of this test. Binding of the antigen-antibody complex to the platelet Fc receptor was not responsible, as Fab and F(ab')2 fragments of one of the antibodies were as effective as intact antibody, and as neither heat-aggregated IgG nor a polyclonal antibody to plasma factor IX inhibited retention. F(ab')2 fragments of 6D1, an antibody to platelet GP Ib that prevents binding of vWf to platelets, also inhibited the second phase of retention. An antibody that inhibits binding of fibrinogen and vWf to GP IIb/IIIa (LJ-CP8) inhibited both the first and second stages of retention, whereas LJ-P5, an antibody that inhibits only the binding of vWf to GP IIb/IIIa, caused slight inhibition of retention when normal or afibrinogenemic blood was used as blood B and was reported to cause only partial inhibition of ADP-induced platelet aggregation in this afibrinogenemic patient. The results suggest that vWf is altered during rapid passage of blood through the glass-bead column so that it attaches to GP Ib, exposing GP IIb/IIIa, which then binds the altered vWf or fibrinogen, either of which can induce platelet aggregation (platelet-platelet adhesion) and thus retention in the column.

Antibodies, Monoclonal↗

PubMed2001

Calcium channel antagonists enhance retention of passive avoidance and maze learning in mice.

Although a number of studies have shown that treatment with calcium channel antagonists (CCAs) can ameliorate impairments in learning and memory in aged animals, evidence for a general nootropic effect of CCAs in neurologically normal young adult animals is ambiguous. This study attempts to resolve some of this ambiguity by comparing the effects of several CCAs on retention of passive avoidance learning and acquisition and retention of appetitively motivated spatial discrimination learning in young adult mice. Animals were trained in a step through passive avoidance apparatus and, immediately after training, injected subcutaneously with different doses of nimodipine, nifedipine, amlodipine, flunarazine, diltiazem, or verapamil. Retention was tested 24 h after training. In the maze-learning task mice were treated with the same doses of the aforementioned CCAs immediately after a brief training session in a linear maze and retention was tested 24 h after training. The most effective dose of each agent in the maze-retention experiment was administered to additional groups of animals 1 h prior to training to determine the effects of CCAs on acquisition processes. The effects of central administration of CCAs were examined by intracerebroventricular injection of different doses of amlodipine immediately after passive avoidance training. Results showed (1) all peripherally administered drugs except verapamil facilitated retention of passive avoidance training in a dose-dependent manner, (2) all drugs dose dependently facilitated retention of linear maze learning, (3) all doses of the drugs (except verapamil) which facilitated maze retention also facilitated maze learning, and (4) central administration of the dihydropyridine amlodipine produced a dose-dependent facilitation of the retention of passive avoidance learning. These data indicate that drugs which block calcium channels can enhance retention of two different types of learning in mice.

Animals↗

PubMed2006

Does two episodes of acute urinary retention lead to additional ischemia-reperfusion injury in rat bladder?

AIM: To determine whether two episodes of acute urinary retention lead to additional ischemia-reperfusion injury due to decompression of the bladder, or not. MATERIALS AND METHODS: Sham, retention and recurrent retention groups consisting of 5, 8 and 8 Wistar Albino male rats were randomized, respectively. After the bladders of rats were emptied with 3F catheter, penile urethras were clamped with aneurism clamp and waited for 30 min after diuresis was forced. At the end of this period, penile clamps were removed and the bladder was again decompressed with 3F catheter and after 30 min removed for examination. In the recurrent retention group, the same process was repeated after an interval of one week. Malonedialdehyde (MDA) levels, indicator of lipid peroxidation and myeloperoxidase (MPO) levels, indicator of leukocyte activation, were examined biochemically in the tissues of the removed bladders. RESULTS: In the retention and recurrent retention groups, the average increase in bladder MDA and MPO values was higher than the values of sham group (P < 0.05), however, no significant difference was determined between retention and recurrent retention groups (P > 0.05). CONCLUSION: In the bladder tissue, due to acute urinary retention and following decompression process, ischemia-reperfusion injury occurs. Two episodes of acute urinary retention do not lead to additional the ischemia-reperfusion injury that develops in the bladder.

Animals↗

PubMed2006

Response to daily 10 mg alfuzosin predicts acute urinary retention and benign prostatic hyperplasia related surgery in men with lower urinary tract symptoms.

PURPOSE: We analyzed the influence of treatment response on the risk of acute urinary retention and benign prostatic hyperplasia related surgery in 5,792 men complaining of lower urinary tract symptoms who were treated for 6 months with the selective alpha1-blocker alfuzosin at 10 mg once daily. MATERIALS AND METHODS: The influence of dynamic variables (International Prostate Symptom Score change and bother during treatment) and baseline variables (patient age, prior acute urinary retention managed conservatively, prostate specific antigen, International Prostate Symptom Score and bother severity) on the risk of acute urinary retention and benign prostatic hyperplasia related surgery was estimated using the Kaplan-Meier method and log rank test. The associated HR and 95% CI were calculated using Cox proportional hazard models. RESULTS: During alfuzosin treatment International Prostate Symptom Score improved by 3 or greater and greater than 6 points in 74.8% and 50.3% of men, respectively. In this unselected population, including 3.8% with prior unoperated acute urinary retention, the rate of acute urinary retention and benign prostatic hyperplasia related surgery events during treatment was low (0.5% and 1.1%, respectively). Men with stable or worsening International Prostate Symptom Score were at increased risk for acute urinary retention or surgery (HR 3.75, 95% CI 1.58 to 8.89, p = 0.003 and HR 4.71, 95% CI 2.69 to 8.24, p <0.001, respectively). Prior acute urinary retention was a strong predictor of acute urinary retention relapse and surgery (HR 10.35, 95% CI 4.29 to 26.08, p <0.001 and HR 3.57, 95% CI 1.59 to 7.98, p = 0.002, respectively). Bother score greater than 3 during treatment was the strongest predictor of surgery (HR 7.61, 95% CI 4.16 to 13.93, p <0.001). Prostate specific antigen had much less predictive value. CONCLUSIONS: This 6-month real life practice study shows that alfuzosin is associated with a low incidence of acute urinary retention and benign prostatic hyperplasia related surgery. It also suggests that responder status is the most important predictor of acute urinary retention and benign prostatic hyperplasia related surgery. Thus, first line treatment with alfuzosin may help select patients at risk for benign prostatic hyperplasia progression to optimize treatment.

Acute Disease↗

PubMedDate not supplied

Urinary retention and the role of indwelling catheterization following total knee arthroplasty.

INTRODUCTION: We aimed to investigate the rate of urinary retention after knee arthroplasty, the various factors involved in predicting those at risk for retention and to assess the impact of retention and catheterization on joint sepsis. MATERIALS AND METHODS: A retrospective review was conducted of all available case notes of patients undergoing total knee arthroplasty in a consecutive 2-year period (2000-2002). Adequate data was available for 142 patients. RESULTS: 142 patients underwent total knee arthroplasty. 19 patients were catheterized preoperatively for monitoring urine output. 123 patients were not catheterized. Urinary retention occurred in 19.7% (28/142). The mean day of catheterization for retention was 0.66. The mean duration of catheterization in patients developing retention was 3.58 days and was 3 days in the patients catheterized pre- or perioperatively. Deep joint sepsis occurred in 2.1% (3/142)--only one had been catheterized and that was preoperatively. No case of infection had urinary retention or had a symptomatic urinary tract infection. The only factors predicting those at significant risk of retention following knee arthroplasty was a past medical history of urinary retention (p = 0.049) and postoperative morphine requirement (p = 0.035). No patients required urological surgical intervention at mean follow up of 1.97 years. CONCLUSIONS: This study supports the use of indwelling urinary catheterization for patients developing urinary retention after total knee arthroplasty.

Aged↗