Extracellular Volume Changes and Blood Pressure Levels in Hemodialysis Patients

Background: Despite the use of highly efficient antihypertensive drugs (AHD), blood pressure (BP) is poorly controlled in the vast majority of hemodialysis (HD) patients. Many of them show no reduction in nocturnal BP, a finding that is associated with left ventricular hypertrophy. The aim of the study was to investigate the effect of the removal of a fluid overload on BP by monitoring the ambulatory BP during 48 hours in 16 hypertensive HD patients treated with AHD. Our aim was to obtain a gradual reduction in post‐HD body weight (BW) over a period of 3 to 4 months. Methods: During a period of 3–4 months, the postdialysis BW was reduced as the minimal tolerable BW was gradually achieved by slightly increasing the ultrafiltration volume. The Na concentration in the dialysate was reduced from 143–141 mmol/L to 139–138 mmol/L. Extracellular volume (ECV) was measured with a multiple‐frequency bioimpedance analyzer (Xitron 4000B, Xitron Technologies Inc., San Diego, CA, USA). Based on the change in ECV, the patients were subdivided into two groups: group 1 with a reduction in ECV (n = 10), and group 2 with no reduction (n = 6). At the start of the study, BW, BP, and AHD in group 1 and group 2 were virtually identical. Results: Group 1 showed a significant reduction during the entire 48‐hour period in systolic (156 ± 16 mmHg vs. 140 ± 14 mmHg, P = 0.030) and diastolic BP (97 ± 12 mmHg vs. 87 ± 9 mmHg, P = 0.026) as well as in mean arterial pressure (MAP, 117 ± 13 vs. 105 ± 10 mmHg, P = 0.027). This reduction was more marked during the night (systolic BP 156 ± 15 mmHg vs. 138 ± 14 mmHg, P = 0.007; diastolic BP 97 ± 12 mmHg vs. 85 ± 9 mmHg, P = 0.009) than during the day (157 ± 18 mmHg vs. 142 ± 15 mmHg, P = 0.067; diastolic BP 97 ± 13 mmHg vs. 90 ± 9 mmHg, P = 0.126). A significant reduction in systolic load also occurred during the entire 48‐hour period (76 ± 24% vs. 46 ± 28%, P = 0.043) as well as in night systolic load (75 ± 21% vs. 41 ± 30%, P = 0.015) and night diastolic load (67 ± 32% vs. 39 ± 31%, P = 0.030). AHD were stopped in eight and reduced in two patients. There were no significant reductions in BP and AHD in group 2. Conclusions: The removal of excess fluid is necessary for adequate BP control and especially for the reduction in elevated BP during the night.     

Volume Control in Hemodialysis Patients

Cardiovascular disease is the main cause of the high mortality of dialysis patients and is largely due to poor control of blood pressure. Establishing and maintaining normal extracellular volume (ECV) is required to achieve normotension. The dry weight concept links ECV and blood pressure by a simple clinical relationship. Dry weight is the ideal postdialysis weight that allows a constantly normal blood pressure to be maintained without using antihypertensive medications. Maintenance of normal ECV requires control of salt intake to reduce interdialytic weight gain ( i.e., saline overload) combined with the diffusive and convective removal of salt and water from the body during dialysis sessions. Several problems are to be faced when using the dry weight method. Clinical evaluation must take into account the following confounding factors: weight varies with nutrition, clinical symptoms are unspecific and sometimes discordant, and there is a lag time between ECV and blood pressure changes. On the other hand, achievement of dry weight is hampered by dialysis times that are too short (and weight gains that are too high), by antihypertensive medications, and by poor heart conditions. A longer session time allows for a slower, easier, and more comfortable ultrafiltration.     

A Comparative Study of C‐Reactive Protein Plasma Levels in Patients on Hemodialysis and Peritoneal Dialysis

In dialysis patients, C‐reactive protein (CRP), a well‐recognized marker of inflammation, predicts mortality. Higher levels have been described in hemodialysis (HD) patients as compared with peritoneal dialysis (PD) patients. Our aim was to determine, based on CRP plasma levels, the degree of inflammation in HD patients using low‐permeability polysulfone membranes and relatively pure dialysate, and that in PD patients. A secondary objective was to study factors associated with hypoalbuminemia and inflammation in both populations. We studied 69 stable patients on dialysis (32 on HD and 37 on PD). The mean age was 69.9 ± 8.2 years, and the mean time on dialysis was 27 months. The two populations were comparable for overall and cardiovascular comorbidities. Nephelometry was used to measure CRP plasma levels (normal levels < 0.6 mg/dL). The Kt/V_urea, corrected for residual renal clearance, and the equivalent of protein nitrogen appearance (PNA) were also calculated. Of the patients studied, 53% showed CRP plasma levels higher than 0.6 mg/dL; in 36%, the levels were higher than 1 mg/dL. No significant differences in these percentages were noted between the two dialysis groups. Patients with CRP levels higher than 1 mg/dL showed lower serum albumin, iron, hemoglobin, and transferrin levels, and higher ferritin values and leukocyte counts. Under logistic regression analysis, CRP levels higher and lower than 1 mg/dL were significantly associated with serum albumin [p = 0.01; odds ratio (OR): 0.15], iron (p = 0.006; OR: 0.96), transferrin (p = 0.004; OR: 0.97), and hemoglobin (p = 0.02; OR: 0.67). Serum albumin levels were significantly lower in PD patients. Under regression analysis, serum albumin levels correlated with cholesterol (r: 0.25; p = 0.04), serum iron (r: 0.5; p = 0.0001), transferrin (r: 0.3; p = 0.015), ultrafiltration capacity (r: 0.42; p = 0.008), and CRP values above 0.6 mg/dL (r: –0.65; p = 0.001). In conclusion, the frequent elevation of CRP plasma levels observed in both HD and PD patients suggests the presence of a silent inflammatory state. Hemodialysis performed with biocompatible, low‐permeability membranes is not associated with higher CRP plasma levels than those seen in PD. In both groups, hypoalbuminemia is related to CRP level. Levels of serum albumin, slightly lower in PD patients, are also related to peritoneal ultrafiltration capacity.     

Factors Affecting Flow-Mediated Vasodilatation in Hemodialysis Patients

Clinical manifestation of overt vascular disease may be preceded for years by endothelial dysfunction. Objective: This study was undertaken to evaluate endothelial function in ESRD patients and correlation between endothelial function and clinical and biochemical parameters. Methods: 32 stable ESRD patients (male : female = 16 : 16, average age: 55.2 ± 13.0) on hemodialysis were included. A 10‐MHz ultrasound transducer was used to image the brachial artery. Brachial artery diameter was measured, and reactive hyperemia was induced by inflation to 250 mmHg for 5 min and then deflation of a pneumatic cuff. After release of the cuff, brachial artery diameter was measured. Results: In the entire study population and non‐diabetic group, the %FMD (% flow‐mediated dilatation, % change of brachial artery diameter between before and after cuff inflation) did not show any significant correlation with duration of dialysis, age, hypertension, albumin, CRP, total cholesterol, LDL and HDL cholesterol, and triglyceride. However, the %FMD of diabetic patients was lower than that of non‐diabetics. Among the patients with diabetes, the group of patients with FMD of <5.2% showed significant lower serum albumin and significantly higher ln(CRP) levels compared to the group of patients with FMD ≥5.2%. The %FMD showed significant positive correlation with serum albumin level and significant negative correlation with ln(CRP) in diabetic patients. Conclusion: These findings suggest that endothelial dysfunction, estimated by FMD, was significantly more prominent in diabetic ESRD, especially with low serum albumin and high CRP levels.     

Hemodynamic and Volume Changes during Hemodialysis

Background: Volume overload is a factor in the hypertension of hemodialysis (HD) patients. Fluid removal is therefore integral to the hemodialysis treatment. Fluid removal by hemodialysis ultrafiltration (UF) may cause intradialytic hypotension and leg cramps. Understanding blood pressure (BP) and volume changes during UF may eliminate intradialytic hypotension and cramps. Studies (S1, S2, and S3) were carried out to determine the amount and direction of changes in body fluid compartments following UF and to determine the relationships between BP, changes in blood volume (ΔBV), central blood volume (CBV), cardiac output (CO), peripheral vascular resistance (PVR) plus total body water (TBW), and intra‐ and extracellular fluid volumes (ICF, ECF) in both the whole body and body segments (arms, legs, trunk). Methods: Indicator dilution technology (Transonic) was used for CBV, CO, and PVR; hematocrit monitoring (Crit‐Line) was used for ΔBV segmental bioimpedance (Xitron) for TBW, ICF, and ECF. Results: S1 (n = 21) showed UF sufficient to cause ΔBV of ?7% and lead to minor changes (same direction) in CBV and CO, and with cessation of UF, vascular refilling was preferential to CBV. S2 (n = 20) showed that predialysis HD patients are ECF‐expanded (ECF/ICF ratio = 0.96, controls = 0.74 [P < 0.0001]) and BP correlates with ECF (r = 0.47, P = 0.35). UF to cause ΔBV of ?7% was associated with a decrease in ECF (P < 0.0001) and BP directly (r = 0.46, P = 0.04) plus ΔBV indirectly (r = ?0.5, P = 0.024) correlated with PVR, while CBV and CO were maintained. S3 (n = 11) showed that following UF, total‐body ECF changes were correlated with leg ECF (r = 0.94) and arm ECF (r = 0.72) but not trunk ECF. Absolute ECF reduction was greatest from the legs. Conclusions: Predialysis ECF influences BP and UF reduces ΔBV and ECF, but CBV and BP are conserved by increasing PVR. ECF reduction is mainly from the legs, hence may cause cramps. Intradialytic hypotension is caused by failure of PVR response.     

Why Our Patients Like Daily Hemodialysis

The option of daily hemodialysis (HD) was discussed in November 1998 with a group of 35 HD patients on home or self‐care/limited‐care HD in a single, freestanding unit. After the meeting, 3 patients on home HD chose to switch to daily HD. The clinical success of the first patient and the immediate followers was one of the main reasons for further extension of this experience. At the time of this writing (February 2000), 10 patients were on a daily HD program (8 at home and 2 in a self‐care/limited‐care center) and one was in training for home daily HD. One further patient who tried 1 month of daily HD dropped out for logistic reasons. On daily HD, patients are dialyzed 2 – 3 hours/day, 6 days/ week, with blood flow of 270 – 300 mL/min, on bicarbonate dialysate with individually determined levels of Na and K. The schedule is flexible and a switch to 3 – 4 dialyses/week is occasionally allowed for working needs or for vacation. In addition to the well‐known clinical advantages (better well‐being, blood pressure control, nutrition, etc.), some patients preferred daily HD because of easier organization of daily activities, including work schedule. Patients initially feared frequent needle punctures and excessive burden on partners, but those concerns proved to be less a problem than anticipated. All current patients are willing to continue daily HD; only a nursing shortage limits further extension of the program in the self‐care/limited‐care center.     

Physiologic Inhibitors of Coagulation in Patients on Chronic Hemodialysis

Patients on hemodialysis are at increased risk for bleeding and thromboses. The intriguing balance between these risks is more complex than once thought, as endogenous clotting factors and their regulators come into contact with bioincompatible dialyzer membranes, in the setting of an extracorporeal circuit of blood flow, in the face of the uremic state. In this review, we summarize the current data on the interaction between the physiologic inhibitors of coagulation and hemodialysis. Data sources and study selection were obtained from research and review articles related to the endogenous anticoagulation pathway published in English on MEDLINE from 1972 to 2002. While protein C activity and protein S antigen concentrations are increased, there is no change in antithrombin III levels during hemodialysis in relation to predialysis levels. Plasma protein Z, which has only recently been studied in uremic subjects, is increased as well. In addition, hemodialysis leads to elevated tissue factor plasminogen inhibitor, thrombomodulin, tissue plasminogen activator, and plasminogen activator inhibitor-1 activities. The potential functional significance of these observations is discussed. Finally, as erythropoietin is commonly prescribed to uremic patients and is recognized to be prothrombotic, an appraisal of its interaction with the naturally occurring anticoagulants is presented. It is apparent that we are only beginning to realize the complexity of the interplay between this myriad of serum factors and hemodialysis. Further research is needed to shed light on this underexplored area of hemodialysis.     

Clinical Characteristics of Upper Gastrointestinal Bleeding in Hemodialysis Patients

Upper gastrointestinal bleeding (UGIB) frequently occurs in hemodialysis (HD) patients. But, clinical characteristics of UGIB in HD patients are not well reported yet.
Objective:  This study was designed to compare the clinical characteristics of UGIB between HD patients and normal population with intact renal function.
Methods:  This study enrolled 24 HD patients with UGIB. Age- and sex-matched 26 patients with UGIB and normal renal function were selected as control group during the same period. Of the cases with UGIB, esophageal variceal bleedings due to liver cirrhosis were excluded in this study. We investigated the results of treatment and UGIB-associated mortality for 3 months after the event and then compared previous gastrointestinal (GI) symptoms (Sx), endoscopic findings, treatment results, and mortality between HD patients and control.
Results:  The results are summarized in the table.  

     

Cirrhosis Ameliorates Renal Osteodystrophy in Patients on Regular Hemodialysis

Cirrhosis (Cir) is often associated with chronic renal failure (CRF) in Egyptian patients on regular hemodialysis (RHD). This is largely attributed to hepatosplenic schistosomiasis and concomitant Hepatitis C viral infection. As the liver has a major role in vitamin D3 activation, we designed this study to envisage the impact of Cir on renal osteodystrophy (ROD). It included 130 consecutive age‐ and gender‐matched subjects in 4 categories. Group I: 39 patients (34 male and 5 female; mean age 48.8 years) with Cir normal renal function; group II: 37 patients (30 male and 7 female; mean age 49.0 years) with CRF and normal liver function, on RHD for a mean duration of 6 ± 3.9 years; group III: 41 patients (30 male and 11 female; mean age 50.7 years) with CRF and concomitant Cir, stable on RHD for a mean duration of 7.0 ± 4.0 years; and group IV: 16 normal volunteers (13 male and 3 female; mean age 46.3 years). The prevalence of diabetes as well as previous infection with schistosomiasis was similar in all patient groups and that of HCV infection was alike in groups I and III. In all subjects, conventional parameters of liver and renal function were tested; in addition to measurement of serum total protein, albumin, calcium, phosphate, total and bone‐specific alkaline phosphatase (B‐ALP), parathormone (PTH), 5‐hydroxycholecalciferol (5HD), 1,25‐dihydroxycholecalciferol (1,25HD), Cross Laps (CXL) as a marker of bone resorption, and aminoterminal propeptide of type I procollagen (PINP) as a measure of bone formation. Bone mineral density (BMD) was measured by either Dual Energy X‐ray Absorptiometry (DEXA) or Computerized Tomography (CT). Group II patients displayed the typical CRF profile comprising hypocalcemia, hyperphosphatemia, increased total and bone‐specific alkaline phosphatases, high PTH and 25HD, low 1,25HD, increased PINP as well as CXL, and generally decreased BMD. Cir (Group III) significantly (p value at least <0.5) modified this profile in several aspects: it checked hypocalcemia (mean 8.8 vs. 7.9 mg/dL in groups II and III, respectively), hyperphosphatemia (5.15 vs. 4.9 mg/dL), and the elevation of B‐ALP (62 vs. 30.5 μg/L) and PTH (89 vs. 78 pg/mL). It lowered the serum level of 25HD (18.7 vs. 13.7 ng/mL), augmented the deficiency of 1,25HD (13.4 vs. 8.0 pg/mL), did not appreciably affect the increase in bone formation (PINP 77.9 vs. 75.5 ng/mL), but ameliorated its excessive resorption (CXL 21 860 vs. 30 328 pmol/L) noticed in group II. This was associated with amelioration of the dialysis‐associated osteopenia (70 vs. 33.5%) and increased incidence of osteosclerosis (30 vs. 61%), as measured by bone mineral density. Conclusion: Our data indicate that Cir ameliorates ROD through decreased bone resorption. This is associated with better tolerance to 1,25HD deficiency, which initiates the cascade of hypocalcemia, hyperparathyroidism, and increased bone resorption in CRF. Such tolerance may reflect upregulation of vitamin D receptors as a consequence of the humoral perturbation supervening in Cir, involving IGF‐1, estrogens, or other vitamin D metabolites as 24,25 HD.     

Relationship of Hypoalbuminemia to Multiple Clinical Factors in Hemodialysis Patients

Research shows that low albumin is correlated with higher morbidity and mortality in the dialysis population. The reasons for this are multi‐factorial and may be related to inadequate protein intake, infection and sepsis, inadequate dialysis, or catabolism of uremia. USRDS data show that ESRD Network 16 tends to have lower albumins compared to other ESRD Networks. Objective: To evaluate albumin status of HD patients at Puget Sound Kidney Centers, Everett, WA (ESRD Network 16) and identify potential factors that may put patients at risk of hypoalbuminemia. Methods: Clinical and biochemical data were collected for 3 months on 221 HD patients. Data included serum albumin (bromcresol purple), calcium, phosphorus, CO₂, Hct, % saturation, ferritin, PTH, BUN, Kt/V, URR, nPCR, hours of HD treatment, interdialytic fluid weight gains, DW changes, incidence of infection and hospitalization, catheter use for dialysis access, presence of diabetes and other co‐morbidities, dialyzer reuse, social/psychological status, and use of nutrition supplements. All biochemical data were collected after the longest interdialytic period and analyzed at the same reference laboratory. Data were averaged for each patient for the 3 months and correlations between parameters were determined using Chi‐square analysis. Results: 25% of all patients had albumins <3.2 g/dL (reference range for normal population 3.5–5.0 g/dL). Patients with lower albumins were significantly more likely to have DM (p < 0.02), use catheters for HD access (p < 0.001), had infections during the previous month (p < 0.001), been hospitalized during the previous month (p < 0.002), have co‐morbid issues (p < 0.001), and use nutrition supplements (p < 0.002). No other factors were significantly correlated with lower albumin. Conclusion: Factors other than nutrition seem to be related to hypoalbuminemia. This study has prompted improved protocols for catheter care and use, infection control, and early intervention for nutrition supplement use. Increased screening and monitoring at‐risk patients (those with diabetes and other co‐morbid conditions) has resulted in improved patient care.     

Effect of Valsalva Maneuver on QT Dispersion in Hemodialysis Patients

Increased QT dispersion seems to be related to an increased risk of arrhythmia and sudden death, a common cause of mortality in hemodialysis (HD) patients. Increase in sympathetic tone has been documented in HD patients. In this study, we aimed to investigate the effect of changes in the autonomic tone on QT dispersion (QTd) in HD patients. Twenty HD patients (M/F 13/7; age, mean ±SD, 28 ± 10 years) and 22 age‐ and sex‐matched healthy controls (M/F 12/10; age, 30 ± 10 years) were included. The patients were dialyzed three‐times weekly; time on dialysis was 17 ± 8 months. The QT durations were measured from 12 lead surface EKGs and were corrected for RR intervals. Corrected maximum (QT_c max) and minimum (QT_cmin) QT intervals and their difference (QT _c d) were recorded. The effect of the Valsalva maneuver in the release phase on QT _c intervals and dispersion was assessed. The HD patients had prolonged values compared to controls: QT _c d, 59 ± 17 ms versus 35 ± 7 ms, p < 0.001; QT _c max, 458 ± 41 ms versus 397 ± 21 ms, p < 0.001; and QT _c min, 398 ± 36 ms versus 362 ± 25 ms, p < 0.001. After the Valsalva maneuver no changes were observed in controls: QT _c max, 397 ± 21 ms versus 396 ± 22 ms, p = 0.9; QT _c min, 362 ± 24 ms versus 358 ± 19 ms, p = 0.5; and QT _c d, 35 ± 7 ms versus 38 ± 10 ms, p = 0.15. Whereas, in HD patients all values were significantly shortened: QT_cmax, 458 ± 41 ms versus 427 ± 35 ms, p = 0.003; QT_c min, 398 ± 36 ms versus 379 ± 34 ms, p = 0.04; and QT_c d, 59 ± 17 ms versus 48 ± 15 ms, p = 0.01. The decrease in QTmax was more prominent than the decrease in QTmin, hence QT dispersion was significantly decreased after the Valsalva maneuver, but differences from controls were still significant. In conclusion, increased sympathetic activity may have a role in the prolonged QT duration and increased QT dispersion in HD patients.     

Role of Genetic Factors in Vascular Access Thrombosis in Hemodialysis Patients

Vascular access thrombosis is a frequent complication in hemodialysis (HD) patients. Genetic mutations, inflammation, and changes in the vascular wall are some factors that are thought to increase thrombosis risk. In this study, we tested for possible relationships between vascular thrombosis and some known thrombophilic mutation/polymorphisms in coagulation factors [factor V Leiden (FVL), prothrombin (Pt) G20210A, methylene tetrahydrofolate reductase (MTHFR C677T), factor XIII (F-XIII) Val34Leu, alpha-fibrinogen (AF) Thr312Ala, factor VII (F-VII) R353Q] and angiotensin I converting enzyme (ACE) gene in our HD patients. Patients who had experienced at least 3 episodes of AVF thrombosis composed of the study group, and patients who had never encountered this complication composed of the control group. None of the patients in either group had a history of diabetes mellitus, atherosclerosis, dialysis-related amyloidosis, or vasculitis. In order to find the frequency of F-XIII Val34Leu, AF Thr312Ala, and F-VII R353Q polymorphisms in our population, we also searched persons without renal disease or history of thrombosis (normal group). Results are summarized in Table. There was a tendency toward thrombotic mutation/polymorphisms in the study group for FVL, Pt G20210A, ACE I/D, and AF Thr312Ala. We suggest that patients who develop recurrent AVF thrombosis should be screened for the above-mentioned factors and investigated for other possible risk factors. This screening would allow more effective focus on prophylaxis.  

     

快速和灵敏地分析常见氨基酸

利用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)和电子轰击(EI)质谱法快速、灵敏地分析了常见的八种氨基酸。并讨论了在不同电离方式下这八种氨基酸的质谱行为,分析结果表明两种方法对测定氨基酸均具有独特之处。     

Survival of End-Stage Renal Disease Diabetic Patients on Hemodialysis

Purpose: To analyze survival and causes of mortality in end‐stage renal disease (ESRD) diabetic patients treated by hemodialysis. Methods: Data of 1203 ESRD hemodialyzed patients between 1975 and 2002 were analyzed, 116 patients were excluded and 1087 patients included in the study. We studied the prevalence of the diabetic nephropathy, the rate of survival and causes of death by comparing diabetic patients with a control group of patients without diabetes. Results: Among the 1087 patients requiring dialysis, 272 (25%) were diabetic and 815 non‐diabetic whose causal nephropathy was nephroangiosclerosis 32%, glomerulonephritis 15%, chronic interstitial nephropathy 14%, and others 14%. The diabetics were older at the beginning of dialysis than non‐diabetic patients: 60.33 ± 11.39 years vs. 52.23 ± 17.20 years, p < 0.001. Average time on dialysis is more important in non‐diabetic than diabetic group [5.90 ± 5.73 years vs. 2.71. ± 2.48 years, p < 0.001]. The rate of death was higher in diabetics than in control group [71.7% vs. 55.8%, respectively, p < 0.003]. The difference in survival between the two groups remains significant for the same age. Death caused by cardiovascular disorders is higher in diabetics (68.8%) than non‐diabetics (31.2%) (p < 0.05). Among death causes, stroke is the most frequent cause in diabetics (18.4% vs. 11.6%) in non‐diabetics, p < 0.05. Death by heart failure and infections is higher in diabetics but the difference is not statistically significant (12.3% in diabetics vs. 9.4% in non‐diabetics for heart failure and 13.8% vs. 11.4% for infections). Death due to neoplasms is higher in non‐diabetics (4.39% vs. 1.02% in diabetics, p < 0.05). Conclusion: In our cohort, mortality in diabetic patients is higher than in non‐diabetic patients. Cardio‐vascular disorders are the most cause of death in diabetics and above all stroke, whereas mortality due to neoplasms is higher in non‐diabetic patients. Diabetes is an important risk factor of mortality in hemodialysis patients.     

Effect of Vitamin E Dialyzer Membrane on Anemia in Hemodialysis Patients

Red blood cell (RBC) survival in patients on chronic maintenance hemodialysis (HD) has been reported to be shortened due to the oxidative damage of RBC membrane. The use of antioxidants might help in the control of anemia and reduce the erythropoietin (EPO) dose needed. Objective: The objective was to determine the effects of vitamin E‐bonded dialyzer membrane (VEM) on anemia and EPO requirements in chronic HD patients. Patients and methods: We prospectively studied 19 stable patients on HD (8 males, age 58.47, range 31–76 years) who were shifted from other dialyzer membranes to VEM for 6 months. At baseline they were given a mean dose of EPO of 90.6 ± 51 U kg^–1 BW^–1 week^–1. Clinical data, dry body weight corrected pre‐dialysis RBC, hemoglobin, reticulocytes, serum iron and ferritin, complete biochemistry, iPTH, and CRP were studied at 3 and 6 months, while therapy scheme was reevaluated monthly. Results: A significant rise, compared to the baseline, was found in hemoglobin and in RBC at 3 months of treatment (12.44 ± 1.16 g/dL vs. 11.2 ± 1.2 g/dL, p = 0.002; and 4.01 ± 0.53 × 10⁶/μL vs. 3.64 ± 0.5 × 10⁶/μL, p < 0.05) and at the end of follow‐up (12.17 ± 1.33 g/dL vs. 11.2 ± 1.2 g/dL, p < 0.05; and 4.03 ± 0.53 × 10⁶/μL vs. 3.64 ± 0.5 × 106/μL, p < 0.05). No significant change in serum iron and ferritin, reticulocytes, EPO dose used, iPTH, Kt/V, or CRP was found at the end of follow‐up compared to the baseline (68.8 ± 17 mg/dL vs. 67.9 ± 18 mg/dL, p = NS; 421 ± 296 mg/dL vs. 478 ± 359 mg/dL, p = NS; 3.76 ± 0.89 × 10⁴/μL vs. 3.82 ± 0.78 × 10⁴/μL, p = NS; 90.2 ± 53 U kg^–1 BW^–1 week^–1 vs. 90.6 ± 51 U kg^–1 BW^–1 week^–1, p = NS; 157 ± 43 pg/dL vs. 148 ± 56 pg/dL, p = NS; 1.21 ± 0.22 vs. 1.2 ± 0.17, p = NS; 7.15 ± 5.42 mg/L vs. 15.38 ± 29.8 mg/L, p = NS, respectively). Conclusions: Despite the small number of patients and the short time interval of treatment, an antioxidant effect of VEM apparently achieved early a better control of anemia in HD patients.     

氨基酸改性聚乳酸共聚物的合成及降解研究进展

为了改善聚乳酸的降解速率,提高其与细胞的亲和性,氨基酸对聚乳酸的改性研究引起了人们的关注。综述了聚(乳酸-氨基酸)共聚物的各种合成路线及产物降解性能的研究进展。在聚乳酸(PLA)分子中引入氨基酸,可以使产物的大分子侧链获得氨基、羟基、羧基等活性基团。与PLA相比,此类聚合物的降解性能有所提高,具有两亲性和良好的细胞相容性,可用于药物缓释体系及组织工程。     

氨基酸分析方法的进展

氨基酸分析方法的研究是绿色工业、绿色农业和生命科学中的比较重要的课题.综述了氨基酸的分析方法,重点介绍了分析测定氨基酸的分光光度法、色谱法和电化学法,展望了氨基酸分析方法的发展趋势.     

氨基酸离子液体对壳聚糖溶解性能的影响

合成了一系列氨基酸类离子液体,从中筛选出对溶解壳聚糖具有良好性能的离子液体——甘氨酸盐酸盐离子液体。在常温常压下考察了该离子液体1%～10%水溶液对壳聚糖的溶解能力,溶解壳聚糖能力最大能达到6.32%(质量分数,下同)。对离子液体重复使用5次后,溶解能力没有明显下降。采用X射线衍射(XRD)和红外光谱(FT-IR)对再生的壳聚糖进行表征,结果表明,壳聚糖在溶解过程中没有发生衍生化。甘氨酸盐酸盐离子液体水溶液是壳聚糖的良溶剂。     

Clinical Consequences of Intermittent Elevation of C-Reactive Protein Level in Hemodialysis Patients

The presence of persistently high C‐reactive protein (CRP) levels is well known to be associated with a state of inflammation, malnutrition, and erythropoietin resistance in hemodialysis (HD) population. Meanwhile, a substantial group of patients present with intermittent elevations of CRP levels, and its clinical consequences are unclear. We designed this study to compare the inflammatory and nutritional parameters and erythropoietin requirements in HD patients with persistent or intermittent CRP elevation and those with CRP levels in without. We included 100 HD patients [age: 48.4 ± 14.3 years; HD duration: 69.3 ± 49.0 months (minimum 12 months)]. The 6‐month retrospective clinical and laboratory data were retrieved from the patient records, and those with chronic inflammatory disease, malignancy, infectious complications, and surgery were excluded. The monthly determined CRP levels (at least 6 for each patient) were reviewed, and the patients were grouped according to their CRP levels as those with persistent (group 1), intermittent (at least one level of CRP 10 mg/L) (group 2), and those with CRP in normal ranges set by the laboratory (group 3). We compared the fibrinogen, ICAM‐1, VCAM‐1, albumin, prealbumin, normalized protein catabolic rate (nPCR), interdialytic weight gain (IDWG), and rHuEPO/kg/Hct results of the patient groups. The patient groups revealed significant differences in terms of fibrinogen (p < 0.001), albumin (p < 0.0001), prealbumin (p < 0.007), ICAM‐1 (p < 00.2) levels and nPCR (p < 0.03), IDWG (p < 0.02), and rHuEPO/kg/Hct (p < 0.03) values. Group 2 presented to be in risk of inflammation and malnutrition with a decrease in albumin levels and nPCR and presence of rHUEpo resistance when compared to patients in group 3. We conclude that, similar to HD patients with persistently high CRP levels, those with intermittent elevation of CRP must also be considered to be in a state of chronic inflammatory response associated with malnutrition and erythropoietin resistance. This signifies the importance of regulatory monitoring of CRP in HD population.     

环保氨基酸型粘合剂的制备研究

以环氧氯丙烷为交联剂对骨胶进行化学改性得到环保氨基酸粘合剂.以初始粘度为指标,氢氧化钠用量、碱解时间、接枝共聚温度、环氧氯丙烷用量和接枝共聚时间为考察因素,做正交实验.结果表明氢氧化钠和环氧氯丙烷的加入量对粘度的影响最大,重点研究这两个因素,选出最佳合成工艺.通过热重分析对胶粘剂的热力学性能进行检测.所制得的粘合剂各项性能均达到GB 18583-2001和HG/T 2727-95要求,其中游离甲醛为0.01g/kg,剪切干强度为13.14MPa,远远高于标准要求.与传统改性相比,环保氨基酸粘合剂的凝固点为-5℃左右,常温呈液态,使用方便,应用范围更广.