High energy, 1572.3 nm pulses for CO2 LIDAR from a polarization-maintaining, very-large-mode-area, Er-doped fiber amplifier

We demonstrate the first polarization-maintaining, very-large-mode-area, Er-doped fiber amplifier with ~1100 μm² effective area. The amplifier is core pumped by a Raman fiber laser and is used to generate single-frequency, one-microsecond, pulses with pulse energy of 541 μJ, peak power of 700 W, M² of 1.1, and polarization extinction > 20 dB. The amplifier operates at 1572.3 nm, a wavelength useful for trace atmospheric CO₂ detection.

A feasibility study into the use of three-dimensional printer modelling in acetabular fracture surgery

There are a number of challenges associated with the operative treatment of acetabular fractures. The approach used is often extensive, while operative time and perioperative blood loss can also be significant. With the proliferation of 3D printer technology, we present a fast and economical way to aid the operative planning of complex fractures. We used augmented stereoscopic 3D CT reconstructions to allow for an appreciation of the normal 3D anatomy of the pelvis on the fractured side and to use the models for subsequent intraoperative contouring of pelvic reconstruction plates. This leads to a reduction in the associated soft tissue trauma, reduced intraoperative time and blood loss, minimal handling of the plate, and reduced fluoroscopic screening times. We feel that the use of this technology to customize implants, plates, and the operative procedure to a patient's unique anatomy can only lead to improved outcomes.

Recurrent IgA nephropathy in renal transplant allografts

Previous reports of renal transplantation for patients with underlying immunoglobulin A (IgA) nephropathy suggested a recurrence rate greater than 50% for transplant IgA nephropathy. Initially regarded as a benign condition, more recent data showed that recurrent transplant IgA nephropathy may be a significant contributor to graft loss. We performed a retrospective analysis in a single center of 48 kidney transplant recipients, all of Chinese origin, with biopsy-proven IgA nephropathy as the cause of end-stage renal failure to determine the recurrence rate of IgA nephropathy in the transplant allograft and subsequent clinical course in Chinese patients. Median duration of follow-up was 52 months (range, 18 to 155 months). Fourteen patients (29%) had biopsy-confirmed recurrent transplant IgA nephropathy after a median of 52 months (interquartile range, 23 to 82 months) posttransplantation. Recurrent transplant IgA nephropathy was associated with greater serum IgA levels (P = 0.01). The presence of HLA-A2 in transplant recipients (P = 0.002) appeared to protect them from developing recurrent IgA nephropathy in the transplant allograft. Twenty-nine percent of patients with recurrent transplant IgA nephropathy had progressive deterioration of graft function. The progressive graft dysfunction (GD) rate was greater in patients with a transplant from a living related donor (LRD; 21%) compared with those with a transplant from a cadaveric or living unrelated donor (URD; 3%; P = 0.062). Although the cumulative graft survival rate was 100% at 5 years for transplants from both LRDs and URDs, the 10-year graft survival rate was only 63% for a graft from an LRD versus 93% for a URD (log-rank test, P = 0.19). A review of other reported series of recurrent transplant IgA nephropathy also showed an apparently greater incidence of GD for a graft from an LRD (28%) compared with a URD (15%). Our data suggest that although recurrent transplant IgA nephropathy is highly prevalent among the Chinese population, the risk for disease recurrence is not particularly increased compared with other ethnic groups. The trend toward a greater risk for GD for living related compared with unrelated allografts in patients with IgA nephropathy needs to be confirmed with further prospective study.

Urea reduction ratio that considers effects of ultrafiltration and intradialytic urea generation

We modified the urea reduction ratio (URR) equation to correct the effects of ultrafiltration and intradialytic urea generation on the delivered dose of hemodialysis: mURR = [1 - (R/1 + 2*UF/BW) + 0.01*t] x 100% where mURR is modified URR, R is postdialysis plasma urea nitrogen (PUN) to predialysis PUN ratio, UF is ultrafiltrate volume in liters, BW is postdialysis body weight in kilograms, and t is dialysis session length in hours. The equation was validated against 145 hemodialysis treatments on 33 stable maintenance dialysis patients. The mURR values obtained closely predicted single-pool Kt/V (spKt/V) values. In contrast to conventional URR, the range of spKt/V values at each mURR value is narrow over a wide range of UF, t, and R values. Based on the mURR equation, mURR values of 64%, 70%, and 76% are mathematically equivalent to spKt/V levels of 1.0, 1.2, and 1.4, respectively. This equation can be a useful bedside tool to quantify hemodialysis dose.

Factors predicting outcome of fungal peritonitis in peritoneal dialysis: analysis of a 9-year experience of fungal peritonitis in a single center

Fungal peritonitis causes significant morbidity and mortality for patients undergoing continuous ambulatory peritoneal dialysis (CAPD). We retrospectively reviewed 70 episodes of fungal peritonitis in a single center over the last 9 years in 896 CAPD patients. Seventy percent of the episodes of fungal peritonitis were caused by Candida species, among which 50% were Candida parapsilosis. As a result of fungal peritonitis, 44% of the patients died, whereas further peritoneal dialysis failed in 14%, requiring a change to long-term hemodialysis. Only 37% managed to continue CAPD. The remaining 5% either underwent transplantation or were lost to follow-up. We identified the factors associated with poor outcome, namely mortality and technique failure. The presence of abdominal pain, bowel obstruction, and a catheter remaining in situ were significantly associated with greater mortality. Abdominal pain, antibiotic use within 3 months before fungal peritonitis, and complication by bowel obstruction were associated with greater technique failure. In choosing antifungal agents with catheter removal, oral fluconazole alone appears equally as effective as combined oral fluconazole with 5-flucytosine for peritonitis caused by Candida species. For peritonitis caused by species other than Candida, the choice of antifungal therapy needs to be individualized, based on fungal species and sensitivities.

A simple assessment of peritoneal transport in stable continuous ambulatory peritoneal dialysis patients

We studied the peritoneal transport properties in 175 stable continuous ambulatory peritoneal dialysis (CAPD) patients seeking a simple and handy assessment of peritoneal permeability to small solutes. Measurement of creatinine in biological fluid was known to suffer from interference by high glucose concentration in the sample. Furthermore, the interference is also affected by the creatinine concentration of the specimen. Peritoneal transport properties were studied by determining the dialysate to plasma ratio of creatinine concentration (D/P) at the fourth hour of the peritoneal equilibration test, and the mass transfer area coefficient of creatinine (MTACCr) or glucose (MTACGlu). The ratio of glucose concentration in peritoneal dialysate effluent (PDE) at 4 and 0 h (G4/G0) was examined and compared with various peritoneal parameters. There were significant logarithmic correlations between D/P or G4/G0 with MTACCr (r=0.96 and 0.79, respectively, p < 0.0001). The correlation between G4/G0 and D/P was linear (r=-0.82, p < 0.0001). A fairly good agreement was present between G4/G0 and D/P by Bland and Altman's method. The bias was -0.93% with 95% confidence interval -23.29% to 21.43% of the measured value. Systematic error was found when D/P or G4/G0 were compared with MTACCr. D/P under estimated MTACCr in the high range. The reverse happened for G4/G0. Net ultrafiltration (NUF) also correlated with MTACCr, D/P and G4/G0 (r=-0.32, p < 0.001; -0.26, p < 0.01; and 0.16, p < 0.05, respectively. In conclusion, the use of G4/G0 as a measure of peritoneal transport in CAPD is an acceptable alternative to D/P. It is highly reproducible and avoids correction of interference when creatinine transport parameters are measured. Because of the logarithmic relations of G4/G0 (or D/P) with MTACCr, the former should not be directly converted to MTACCr. Such a simple measure of peritoneal permeability is, however, most convenient for serial monitoring and can be useful to detect early loss of ultrafiltration or solute clearance.

Treatment of pulmonary embolism by subcutaneous low-molecular-weight heparin in a hemodialysis patient

Low-molecular-weight heparin (LMWH) has been used in the prophylaxis and treatment of deep vein thrombosis. Data regarding the efficacy of this drug without subsequent use of oral anticoagulant in the treatment of pulmonary embolism is limited. Pulmonary embolism may complicate the use of central venous catheter in hemodialysis. We report a case of acute submassive pulmonary embolism complicating a central venous hemodialysis catheter in a dialysis patient. After the catheter was removed, the patient was treated successfully with subcutaneous injection of LMWH for three months. We conclude that LMWH is safe and effective for treatment of pulmonary embolism in patient on hemodialysis.

Posttransplant Epstein-Barr virus-associated myogenic tumors involving bone

BACKGROUND

Epstein-Barr virus (EBV)-associated myogenic tumors in immunocompromised patients were recently recognized, but their biologic behavior remains only partially understood. Although observations so far have permitted the recognition of similarities between posttransplant myogenic tumors and posttransplant lymphoproliferative disorders (PTLD), the number of reports are still few, and new experiences continue to be informative.

METHODS

The authors describe what they believe is the first example of posttransplant EBV-associated myogenic tumor involving bone, which is also remarkable for its multicentric symmetric limb distribution. Immunohistochemistry of tumor cells for myogenic antigens (desmin and smooth muscle actin), EBV antigens (latency proteins latent membrane protein-1 [LMP-1], Epstein-Barr nuclear antigen-2 [EBNA-2], and ZEBRA), p53, and bcl-2 was examined by standard avidin-biotin-peroxidase complex methods. Molecular techniques investigated in situ hybridization for Epstein-Barr virus-encoded messenger RNAs (EBERs) and single-strand conformation polymorphism analysis for p53 mutation.

RESULTS

Although the biologic behavior of this tumor was uncertain, the reduction of immunosuppression arrested tumor growth for 5 years, at the expense of some loss in renal function. The occurrence of episodes of acute cellular rejection required pulse therapy, resulting in the appearance of new lesions in both liver and lungs. Despite these complications, a balance between control of this multicentric tumor growth and allograft survival has been maintained for 8 years.

CONCLUSIONS

To the authors' knowledge, this example of posttransplant myogenic tumor is the first described in the bone. It shows partial response to immunomodulation with persistent tumor, with prolonged survival of the renal allograft.

Independent effects of residual renal function and dialysis adequacy on nutritional status and patient outcome in continuous ambulatory peritoneal dialysis

Dialysis adequacy has a major impact on outcome of continuous ambulatory peritoneal dialysis (CAPD) patients. However, there is a substantial confounding effect by residual renal function in most studies. We differentiated the effects of dialysis adequacy from those of residual renal function on nutritional status and outcome of CAPD patients. We identified 168 CAPD patients treated in our center between September 1995 and December 1996 and categorized them into three groups: 49 patients with an average total Kt/V of 1.93 +/- 0.18 and a median residual glomerular filtration rate (GFR) of 0. 07 mL/min/1.73 m(2) in the dialysis-dependent (DD) group; 48 patients with an average total Kt/V of 2.03 +/- 0.25 and a residual GFR of 2. 33 mL/min/1.73 m(2) in the residual renal function (RRF) group; and 71 patients with an average total Kt/V of 1.38 +/- 0.22 and a residual GFR of 0.05 mL/min/1.73 m(2) in the control (CTL) group. They were followed-up for 1 year to compare baseline nutritional status and 1-year morbidity. Baseline normalized protein catabolic rates (NPCR) are 1.00 +/- 0.20 and 0.96 +/- 0.19 (for RRF and DD, respectively) versus 0.89 +/- 0.16 g/kg/d for CTL (P < 0.01). Percentage lean body mass (%LBM) was 71.6 +/- 9.8 and 71.5 +/- 10.0 (for RRF and DD, respectively) versus 65.2 +/- 8.5% for CTL (P < 0. 001). No difference was seen in the nutritional status between RRF and DD groups. Duration of hospitalization for 1 year was 6.9 +/- 11. 8 days in the RRF group versus 14.9 +/- 25.1 in the DD and 10.6 +/- 11.6 days in the CTL groups (P < 0.05). The peritonitis rate was 44. 4 patient-months for the RRF group, versus 13.6 for the DD and 12.9 for the CTL groups (P < 0.05). There also was a trend toward superior 1-year technique survival in the RRF group, but the number of observations was small. There was no difference in duration of hospitalization, peritonitis rate, and technique survival between the DD and CTL groups. Short-term morbidity in patients without residual renal function appears to be independent of total Kt/V, although Kt/V may have some effects on nutritional status. The assumption that renal and peritoneal clearances are equivalent must be carefully reexamined. Further studies on the effect of dialysis adequacy in patients without residual renal function are urgently needed.

Neutrophilic transient acidification and superoxide production in peritoneal dialysate

AIM

To elucidate whether an inhibited superoxide production (O2-) of neutrophils induced by commercial lactate-based peritoneal dialysates (PDS) could be corrected after a transient intracellular acidosis.

METHODS

The intracellular pH ([pHi]) of human neutrophils incubated in PDS was monitored with a spectrofluorometer with a pH-sensitive dye (BCECF-AM). Neutrophilic O2- stimulated by zymosan was determined in PDS with the superoxide dismutase inhibitable ferricytochrome c reduction, using a spectrophotometer.

RESULTS

The severe intracellular acidosis induced within 5 min by PDS at an extracellular pH of 5.2 could be promptly and completely recovered by a neutralization of the pH of media. However, O2- by neutrophils exposed to the PDS for as little as 5 min was drastically and persistently inhibited, even the acidic [pHi] of cells had been fully returned for 1 h.

CONCLUSIONS

The intracellular acidification of cells in the initial phase could be transient and reversible, but impaired cell functions, at least in part including O2- generating system, might be consistent and irreversible in the early stage of the cellular acidosis in the peritoneal cavity of CAPD patients. The findings above may be of particular importance in both clinic and cell biology.

The effects of perinatal hypoxic risk on developmental outcome in early and middle childhood: a twin study

The goal of this study of 66 twins was to determine whether motor and cognitive functions assessed in early and middle childhood are vulnerable to perinatal hypoxic risk. In an earlier study of 76 infant and toddler twins (S. Raz, F. Shah, & C. Sander, 1996), the authors found that intrapair discrepancy on the Mental Developmental Index, but not on the Psychomotor Developmental Index, of the Bayley Scales of Infant Development was associated with discordance for perinatal hypoxic risk. The twins at lower risk outperformed their higher risk co-twins. In the present study the authors sought to establish in a new sample of preschool and school-age twins whether gaps in performance persist into early and middle childhood. Although the disparity in hypoxic risk between the co-twins was typically moderate, significant intrapair differences were observed on the measure of motor performance. Among the motor abilities examined, skills involving visually guided ballistic arm movements appeared to be the most vulnerable to perinatal risk.

Pain perception following subcutaneous injections of citrate-buffered and phosphate-buffered epoetin alpha

Subcutaneous injection of citrate-buffered epoetin alpha (EPO-alpha) causes pain. Substitution of citrate buffer with a phosphate buffer in the EPO-alpha resulted in a significant reduction in duration and severity of pain. It is possible that sodium citrate which is present in the EPO-alpha may be the agent that causes discomfort in the patients.

Pyruvate-based peritoneal dialysate preserves neutrophilic oxygen consumption

AIM

To investigate effects of pyruvate- or lactate-based peritoneal dialysis solutions (P-PDS or L-PDS) on neutrophilic oxygen consumption and the role of the extracellular pH (pHe) in cells' oxygen uptake.

METHODS

Human neutrophils were incubated in P-PDS or L-PDS containing pyruvate or lactate 35-38 mmol.L-1 at various pHe, respectively. Oxygen consumption rates by opsonized zymosan (OZ)-stimulated cells were measured polarographically, using a Clark-type oxygen electrode.

RESULTS

L-PDS at an initial pH 5.2 dramatically inhibited the rate of oxygen consumption (2.2 nmol.min-1/10(6) cells) by neutrophils, while the equally acidic P-PDS markedly improved the rate (6.4 nmol.min-1/10(6) cells) (P < 0.01). However, P-PDS at pHe 5.2 severely impaired the rate by cells, the same as pHe 5.2 L-PDS.

CONCLUSION

P-PDS preserved an oxygen consumption rate by OZ-stimulated human neutrophils, but in an acidi milieu it comparably deteriorated the ability of cells to consume oxygen, indicating that the pHe of PDS plays an essential role in cellular oxidative metabolism. The superior biocompatibility of an acidic P-PDS was associated with its lower buffering capacity.

Acid-base values of single pass, batch system, bicarbonate based hemodialysate

The bicarbonate, calcium, and magnesium values of a single pass, batch system, bicarbonate based hemodialysate were found to be stable during a period of 5 hours, whether the solution was extensively covered by a floating polystyrene lid or not. The pH and PCO2 of the dialysate that had been covered with a floating lid remained stable during the 5 hours, whereas the corresponding values of the dialysate that had not been so covered did show changes that were secondary to the loss of carbon dioxide. The changes were not marked enough to preclude the clinical use of the latter uncovered dialysate.

Single-mode high-peak-power passively Q-switched diode-pumped Nd:YAG laser

We have demonstrated an efficient, compact, passively Q-switched single-mode diode-pumped Nd:YAG laser that uses Cr(4+):YAG as a saturable absorber. Linear- and ring-cavity configurations were demonstrated. Pulse energies and widths were, respectively, 1.5mJ and 3.9ns for the linear cavity and 2.1mJ and 12ns for the ring cavity.

Association of IgA nephropathy with T-cell receptor constant alpha chain gene polymorphism

T-cell receptor (TCR) proteins recognize a complex of an antigen-derived peptide bound to the cell surface products of the major histocompatibility complex (MHC) that could be of importance in the immunopathogenesis of IgA nephropathy (IgAN). Previous studies found no difference on TCR constant beta chain gene frequencies in IgAN compared with control. Yet no study on the TCR alpha gene in IgAN was reported. We studied the TCR C alpha gene polymorphisms by restriction fragment length polymorphism (RFLP) in 53 patients with IgAN and in comparison with 67 healthy controls. The patients were also classified into different histopathological grading (I, II, and III with increasing histological severity) and renal functions. The extracted DNA were digested with Taq I enzymes and probed with a full-length TCR-alpha cDNA clone p1.2alpha probe. A 7-kb C-alpha Taq 1 fragment is found in 32 of 53 patients (60.3%) compared with 26 of 67 controls (38.8%) (P < 0.05). There was no association of any polymorphic fragment, including the 7-kb fragment, with either the histological grading or renal function. It is concluded that the TCR C-alpha gene is associated with IgAN but not with the prognosis of the disease.

Dialysis adequacy of Asian patients receiving small volume continuous ambulatory peritoneal dialysis

The usage of three x 2 liter daily exchanges is adopted as the standard CAPD regime in Hong Kong over the last 10 years due to budgetary constraint. This dialysis prescription is considered suboptimal in Western standard. However, the necessity of maintaining Kt/V > 1.7 for CAPD dialysis adequacy is not unanimously agreed. We performed a cross-sectional study of 117 patients on CAPD. Seventy-eight percent of our patients had 3 x 2 liter daily exchange while the rest had 4 daily exchanges. Fifteen percent of patients were diabetic. Patients with Kt/V < 1.7 were similar to those with Kt/V > 1.7 in age, duration of CAPD, BUN, plasma creatinine, albumin, peritonitis rate, and incidence of hypertension. Patients with Kt/V > or = 1.7 had higher hemoglobin, higher nPCR, more residual renal function; and more of them received 4 daily exchanges. Their peritoneal permeability did not differ. Their employment and rehabilitation status was also similar. Our 5-year survival was 79% despite a lower Kt/V. Notably, the protein catabolic rate of our patients was higher than that in Western patients. This is likely due to dietary difference. Our study suggests small-volume dialysis may be acceptable in Asian population with smaller body size given the financial constraint.

Splanchnic erythrocyte content decreases during hemodialysis: a new compensatory mechanism for hypovolemia

Splanchnic and splenic erythrocyte volumes decrease during postural changes and exercise to help maintain central blood volume and cardiac output. The contribution of this compensatory mechanism to hemodynamic stability during dialysis has not been studied, however. In 8 ESRD patients, age 51.0 +/- 4.5 years old, we measured changes in the splanchnic/splenic erythrocyte volume during dialysis by tagging the patients' erythrocytes with technetium and following abdominal radioactivity over time. Splanchnic radioactivity decreased to 90.2 +/- 3.8% (mean +/- SEM) of the baseline value after 2 hr of accelerated fluid removal (3.7 +/- 0.4 liters) during dialysis (DUF), while it remained relatively unchanged after two hours of dialysis without fluid removal (DD) [106.5 +/- 2.3%, P (DUF vs. DD) = 0.03]. Splenic radioactivity decreased to 89.2 +/- 5.0% of the initial value during DUF versus 103 +/- 3.8% during DD, but the decrease was noted only during the last 30 minutes of DUF and did not attain statistical significance. Autonomic nervous system integrity was measured by the spontaneous variation of the R-R interval during deep respiration (E/I ratio) and by the Valsalva ratio. The mean E/I and Valsalva ratios in the eight patients were 1.13 +/- 0.03 (+/-SEM) and 1.42 +/- 0.1 respectively, suggesting reasonably adequate autonomic nervous system functioning. The results suggest that contraction of the splanchnic, and possibly the splenic, vascular beds occurs during fluid removal associated with hemodialysis. The resultant addition of erythrocytes to the circulation may help maintain central blood volume and cardiac output.

Effects of pyruvate-based or lactate-based peritoneal dialysis solutions on neutrophil intracellular pH

Acidic (pH 5.2) incubation mixtures containing pyruvate-based or lactate-based peritoneal dialysis solutions (PDSN's) induced comparable degrees of intracellular acidosis in neutrophils. However, addition of an acidic (pH 5.2), pyruvate-based PDSN to a pH-7.4, neutrophil/phosphate-buffered saline mixture brought about higher extracellular and intracellular (neutrophil) pH values when compared to the introduction of an equally acidic, lactate-based PDSN. This poor ability of acidic (pH 5.0-5.5), pyruvate-based PDSN's to resist alkalinizing influences is the cause for the above higher pH values. The higher intracellular pH levels so obtained may be a reason behind why acidic, pyruvate-based PDSN's appear to be more biocompatible than their equally acidic, lactate-based counterparts.

Xanthomonas maltophilia peritonitis in uremic patients receiving continuous ambulatory peritoneal dialysis

Xanthomonas maltophilia peritonitis has been only occasionally reported in patients receiving continuous ambulatory peritoneal dialysis. We present a series of six cases of peritonitis caused by such bacteria, accounting for 1.5% of all peritonitis episodes encountered in our renal unit over the past 5 years. Recent bacterial peritonitis treated with broad-spectrum antibiotics was the major risk factor, and the outcome was poor with medical treatment alone. Secondary peritonitis, especially fungal, was common and probably related to the prolonged course of antibiotics. All patients eventually required removal of the catheter, either because the effluent failed to clear up or because of secondary peritonitis. We suggest that X maltophilia peritonitis be treated with double antibiotics as soon as it is diagnosed. To prevent the development of superimposed infection after prolonged administration of antibiotics, the Tenckhoff catheter should be removed if the peritonitis fails to respond to a short course of antibiotics.

Effects of a pH 7.4, lactate-based and a pH 7.4, bicarbonate-based peritoneal dialysis solutions on neutrophil superoxide generation

Neutrophil superoxide formation was similar when cells were incubated in self-made, non-autoclaved pH 7.4, lactate-based peritoneal dialysis solutions or in their self-made, non-autoclaved, pH 7.4, bicarbonate-based counterparts. On the other hand, commercially available, autoclaved, pH 7.4, lactate-based peritoneal dialysis solutions resulted in inhibition of superoxide production when compared to their self-made, non-autoclaved, pH 7.4, lactate-based or bicarbonate-based counterparts. The cause for this inhibition of superoxide generation is at present unknown.

Use of low-dose low molecular weight heparin in hemodialysis

We investigated the lowest effective dosage of low molecular weight (LMW) heparin for hemodialysis in comparison to unfractionated (UF) heparin. Initial hemodialysis sessions were undertaken in 10 uremic patients with UF heparin of the dose habitually required for each patient. Four-hour hemodialysis sessions were then undertaken with LMW heparin (nadroparin) in a single bolus (200 anti-Xa unit Institut Choay/kg [aXaU IC/kg], 175 aXaU IC/kg, 150 aXaU IC/kg, or 125 aXaU IC/kg; two sessions for each dosage). Anti-Xa levels and activated partial thromboplastin time (APTT) were monitored hourly during dialysis. Fiber bundle volume of dialyzer was measured before and after dialysis. Urea clearance was determined at the onset and completion of dialysis. There were no episodes of excessive bleeding, clotting of dialyzers, or clots in air traps with UF heparin or LMW heparin. A 35% increase in APTT above baseline was observed in all dialysis sessions 1 hour after LMW heparin bolus, but the APTT decreased rapidly thereafter. The anti-Xa levels exceeded 0.5 U/mL for all sessions using LMW heparin irrespective of the dosage. No significant reduction of urea clearance was found in dialysis with either UF or LMW heparin. No reduction of fiber bundle volume of dialyzer was observed in dialysis with either UF or LMW heparin, although a small reduction (3%) was observed in dialysis with LMW heparin at 125 aXaU IC/kg. We concluded that the use of LMW heparin for hemodialysis is safe and effective as compared with UF heparin. The lowest effective dosage can be reduced to 125 aXaU IC/kg in high-risk patients to reduce hemorrhagic complications.

Neutrophil attractant protein-1 interleukin 8 and its autoantibodies in IgA nephropathy

Human neutrophil attractant protein-1/interleukin 8 (IL-8) has been shown to activate neutrophils to degranulate in vitro and to be a potent chemotactic agonist for neutrophils and lymphocytes in vitro and in vivo. There is accumulating evidence that neutrophils are involved in inflammatory injury in IgA nephropathy (IgAN). We studied the serum levels of IL-8 and its autoantibodies of the IgA or IgG class in 36 patients with IgAN in comparison with 31 healthy controls and 26 patients with other primary glomerulonephritides (CGN). Interleukin 8 was more frequently detected in sera of patients with IgAN and their serum levels were significantly higher than those of healthy controls. The free IL-8 autoantibodies of the IgA, but not IgG class, were more frequently detected in patients with IgAN and their serum levels were significantly elevated compared with both groups of controls. The complexed IL-8 autoantibodies of either class were not different among the three groups of subjects. Again the ratio of free to complexed IL-8 autoantibodies of the IgA class was raised in patients with IgAN. Histologic examination revealed increased polymorphs and monocyte/macrophage infiltration in IgAN compared with other glomerulonephritides. When the serum levels of IL-8 and IL-8 autoantibodies were compared between IgAN patients with milder pathology and those with more severe pathology, the latter group had significantly higher serum levels of free and complexed IL-8 autoantibodies of the IgA class. These observations suggest a possible role for IL-8 and its autoantibodies of the IgA class in the inflammatory process of IgAN. These autoantibodies may provide a clinically useful marker for the diagnosis of disease severity.

Serologic study of immunoglobulin A-fibronectin aggregates in immunoglobulin A nephropathy

The immunoglobulin A (IgA)-fibronectin aggregates, detected by enzyme-linked immunosorbent assay using either antifibronectin or collagen I as binding protein, were previously found to be raised in the circulation of patients with IgA nephropathy (IgAN). It has been suggested that IgA-fibronectin aggregates are involved in the pathogenesis and that the plasma IgA-fibronectin level may even be of diagnostic value in IgAN. Nevertheless, a recent report has questioned the specificity of these assays as plasma IgA may interact with immobilized IgG and these assays detect not only IgA-fibronectin, but also total plasma IgA. These doubts render the interpretation of raised IgA-fibronectin aggregates in IgAN impossible. We isolated total IgA, in plasma by jacalin-agarose. Monomeric and polymeric IgA1 were distinctly separated by fast protein liquid chromatography. When the fast protein liquid chromatography fractions were analyzed for IgA-fibronectin using the antifibronectin capture assay, increased optical density values were predominantly observed in polymeric IgA but not in monomeric IgA. Similar findings were found when the fast protein liquid chromatography fractions were studied using a novel gelatin-anti-IgA assay that avoided nonspecific interaction between plasma IgA and immobilized IgG used as the capture antibody in antifibronectin capture assay. Using our gelatin-anti-IgA assay, we failed to demonstrate a diagnostic increase in IgA-fibronectin aggregates in polymeric IgA from patients with IgAN compared with controls. Our finding of circulating IgA-fibronectin aggregates in patients with IgAN comparable to those of healthy controls did not support the notion that these aggregates may have a pathogenetic role or diagnostic value in IgAN.

Effect of an pyruvate-based peritoneal dialysis solution on the pH of a residual peritoneal dialysis fluid

An acidic (pH 5.2) pyruvate-based peritoneal dialysis solution or an equally acidic lactate-based counterpart was added to a residual fluid (i.e., peritoneal effluent) obtained from each of 6 continuous ambulatory peritoneal dialysis patients. It was found that the residual fluids were able to raise the pH of the resultant residual fluid/peritoneal dialysis solution mixture to a higher level in the case of the pyruvate-based solution than in the case of the lactate-based one.

Use of a phosphorus-enriched dialysate in a hypercatabolic renal failure patient receiving intensive hemodialysis therapy

An elderly man with end-stage renal disease required intensive hemodialysis therapy because of sepsis-induced hypercatabolism. We were able to prevent the occurrence of hypophosphatemia by using a phosphorus-enriched dialysate during hemodialysis treatments.

Effect of dialysate temperature on central hemodynamics and urea kinetics

Use of cool dialysate is associated with increased intradialytic blood pressure, but the hemodynamic mechanism is unknown. Whether changes in dialysate temperature affect muscle blood flow, which may the alter the degree of urea compartmentalization, also is unknown. We measured hemodynamics and blood and dialysate-side urea kinetic indices in nine hemodialysis patients during two cool (35.0 degrees C) versus two warm (37.5 degrees C) dialysate treatments. The % change in mean arterial pressure was different when using the cool (+6.5 +/- 9.7 mm Hg) versus the warm (-13.4 +/- 3.6) dialysate (P < 0.01), despite comparable amounts of fluid removal. Percent changes in cardiac output were similar with the two dialysates, and thus the blood pressure effect was due primarily to changes in total peripheral resistance (% delta TPR, cool +26 +/- 13.6, warm +8.6 +/- 14.5; P < 0.02). During cool dialysate use tympanic membrane temperature changed by -0.51 +/- 0.23 degree C, whereas body temperature increased by 0.52 +/- 0.14 degree C during use of warm dialysate. Measured urea recovery normalized to the predialysis urea nitrogen concentration was similar with the two treatments: cool 31.3 +/- 0.039 liter-1; warm 29.7 +/- 0.021; P = NS. In a second study, post-dialysis urea rebound values from 15 seconds to 30 minutes, expressed as the percent of the post-dialysis SUN, were similar after the two treatments: cool 11.79 +/- 1.4; warm 12.21 +/- 2.27, P = NS.(ABSTRACT TRUNCATED AT 250 WORDS)

Collection of a representative fraction of total spent hemodialysate

We describe a method of obtaining a small representative fraction of spent dialysate by placing a side tube in the dialysate drainage tube. The side tube, capped with a small-gauge needle, is used to collect the specimen. Fractions obtained in this fashion are found to have a composition similar to that of the remaining spent dialysate.

Neutrophil intracellular pH after exposure of neutrophils to a euhydric, lactate-based peritoneal dialysis solution and its euhydric, bicarbonate-based counterpart

The effects of euhydric, lactate-based peritoneal dialysis solutions and those of their euhydric, bicarbonate-based counterparts, on neutrophil intracellular pH are comparable. This similarity in effects on intracellular acidity may have bearings on the influences of these solutions on cellular functions in general.

Continuous ambulatory peritoneal dialysis using self-made, ultrafiltration-sterilized, L-lactate-based dialysis solution

Continuous ambulatory peritoneal dialysis was successfully carried out in 6 end-stage renal failure patients using self-made, ultrafiltration-sterilized dialysis solutions. A Y-set was used to deliver the above solutions to sterile plastic bags.

Efficient, diode-laser-pumped, diode-laser-seeded, high-peak-power Nd:YLF regenerative amplifier

Optical amplification of 11 orders of magnitude in a microlens-collimated, diode-laser-pumped regenerative amplifier has been demonstrated. The amplifier was seeded with 20-ps pulses from an FM mode-locked oscillator and with 0.9-ns pulses from a modulated diode laser. Seed pulses from both sources were amplified to energies exceeding 2.5 mJ. With the thermoelectric coolers and the Pockels cell electronics neglected, the diode-seeded system exhibited an electrical-to-optical efficiency of 2.2%.

Detection of functional and dimeric activin A in human marrow microenvironment. Implications for the modulation of erythropoiesis

Activin A, which was initially recognized as a gonadal protein, was implicated in the modulation of erythropoiesis through a paracrine control in the bone marrow microenvironment. Present studies demonstrate that, in contrast to T lymphocytes and cultured skin fibroblasts, human marrow stromal cells produce a functional and dimeric beta A beta A molecule (i.e., activin A). RT-PCR further indicates that both alpha and beta A mRNAs of inhibin A/activin A are produced in human stromal cells. The level of beta A subunit mRNAs, however, is in large excess over that of alpha subunit mRNAs, suggesting the predominant production of beta A beta A dimers, as well as some inhibin A (alpha beta A). It should be noted, however, that the beta A subunit can form dimeric proteins other than activin A, such as activin AB (beta A beta B) and inhibin A (alpha beta A). Hence, the presence of the beta A subunit may not necessarily indicate the production of the activin A molecule in any tissue. Therefore, a special quantitative sandwich ELISA assay specific for the dimeric beta A beta A molecule was developed for the measurement of activin A. With this assay, production of activin A in marrow stromal cells is found to be greatly enhanced by cytokines and inflammatory mediators such as TNF-alpha, IL-1 alpha, and lipopolysaccharide. These studies thus suggest that inflammatory cytokines are the inducers for activin A, probably serving a role of up-regulating activin A production locally in bone marrow microenvironment. At present, activin A is not known to play any role in inflammatory reaction; this study may thus raise the possibility that activin A performs more functions than are currently recognized. Alternatively, the enhanced production of this molecule in the bone marrow microenvironment may be regarded as a compensatory mechanism in host defenses, countering inflammatory mediators that are known to suppress erythropoiesis.

Failure of neutrophils to recover their ability to produce superoxide after stunning by a conventional, acidic, lactate-based peritoneal dialysis solution

Exposure of human neutrophils to conventional, acidic, lactate-based peritoneal dialysis solutions for 5 minutes results in a depression of superoxide generation. In spite of restoration of extracellular pH to 7.4, these stunned cells failed to recover their ability to generate the anion after a period of an hour.

Inadequate superoxide production by canine neutrophils in response to the combination of N-formyl-methionyl-leucyl-phenylalanine and cytochalasin B

The formylated peptide, N-formyl-methionyl-leucyl-phenylalanine, at concentration of 0.22 microM, failed to stimulate canine neutrophils to produce adequate amounts of superoxide. Furthermore, addition of cytochalasin B did not augment superoxide generation appreciably.

Employing L-lactic acid powder in the preparation of a dry "acid concentrate" for use in a bicarbonate-based dialysis solution-generating system: experience in hemodialysis patients

By replacing the liquid acetic acid present in the "acid concentrate" of a bicarbonate-based dialysis solution-generating system with an equimolar amount of solid L-lactic acid and by using the dry forms of the remaining constituents, we were able to create a dry "acid concentrate" just prior to use, and successfully employed this "acid concentrate" to produce a bicarbonate-based solution to hemodialyze patients.

Effects of an acidic, lactate-based peritoneal dialysis solution and its euhydric, bicarbonate-based counterpart on neutrophilic intracellular pH

An exposure of human neutrophils to an acidic (pH 5.2), lactate-based incubation mixture containing a conventional, acidic, lactate-based peritoneal dialysis solution (PDS) resulted in the development of a prompt and substantial intracellular acidosis. A comparable exposure to a euhydric, bicarbonate-based incubation mixture containing a euhydric, bicarbonate-based PDS did not bring about similar changes in intracellular pH. The absence of an intracellular acidosis in the instance of the euhydric, bicarbonate-based PDS may be the reason why this solution is more biocompatible than its acidic, lactate-based counterpart.

Hemodynamic effects of intradialytic food ingestion and the effects of caffeine

Although the hypotensive effects of food ingestion during hemodialysis have been documented, the hemodynamic mechanism is unclear. It could be decreased cardiac output due to splanchnic sequestration or decreased vascular resistance due to splanchnic vasorelaxation. Also, the effects of caffeine, which block postprandial hypotension in the elderly, have not been studied in a dialysis setting. Central hemodynamics were monitored by thoracic electric bioimpedance in 10 dialysis patients who ingested a test meal 1 h into dialysis. All ultrafiltration was done during the initial 2 h. Bicarbonate dialysate was used. Each patient was studied three times in a double-blind (with respect to placebo/caffeine) cross-over trial: placebo/no meal, placebo/meal, and caffeine/meal. Blood pressure decreased sooner and to a great extent in the treatments in which food ingestion accompanied ultrafiltration (e.g., at 30 min after food ingestion, percent change in mean arterial pressure was -12.4 +/- 1.8 versus -2.4 +/- 3.5 mm Hg when food was not ingested; P < 0.05). The hemodynamic mechanism of food-associated hypotension was found to be a fall in systemic vascular resistance (SVRI). Caffeine pretreatment (200 mg), which resulted in intradialytic plasma caffeine levels of about 4 micrograms/mL at time of food ingestion, had no effect on food-associated reductions in blood pressure or SVRI. The results suggest that food ingestion during dialysis causes hypotension primarily because of decreased SVRI. The effects of food ingestion on mean arterial pressure and SVRI are not attenuated by the ingestion of 200 mg of caffeine 1 h before dialysis.

Increasing plasma phosphorus values by enriching with phosphorus the "acid concentrate" of a bicarbonate-buffered dialysate delivery system

Each of seven hypophosphatemic hemodialysis patients was dialyzed with a phosphorus-enriched, bicarbonate-buffered dialysate. The latter was prepared by the introduction of sodium phosphate salts to the "acid concentrate" of a bicarbonate-buffered dialysate delivery system. The patients tolerated the procedure well and their hypophosphatemia improved.

Peritoneal dialysis using conventional, lactate--containing solution sterilized by ultrafiltration

Peritoneal dialysis was performed on 7 end-stage renal failure patients using an I-lactate-containing solution sterilized by ultrafiltration through polyamide filters. The patients tolerated the procedure well while their metabolic acidosis and azotemia improved.

Neutrophilic intracellular acidosis induced by conventional, lactate-containing peritoneal dialysis solutions

Exposure of human neutrophils to a conventional, acidic, lactate-containing peritoneal dialysis solution (PDS) resulted in the development of a prompt and substantial intracellular acidosis. It is possible that this intracellular acidosis contributes to cellular dysfunction.