Biomedical subjects

A K Cheung

Publications and source records attributed to A K Cheung.

At least 19 recordsLinked to original sources

PubMed2002

Kinetics of porcine circovirus type 2 replication.

The kinetics of porcine circovirus type 2 (PCV2) replication in PK15 cells was examined. During productive infection, viral antigens, RNA transcripts and progeny viruses all increased in a time dependent manner. Viral antigens were observed in a few cells at 18 hour postinfection (h p.i.) and cell-free progeny viruses began to appear at about 30 h p.i. Viral transcripts were detected by 18 h p.i. and the capsid protein RNA of 950 nucleotides (nt) was the most abundant RNA species. Two other RNAs of sizes 750 and 450 nt, derived from the predicted replication associated protein (Rep) gene region, were also detected. These two RNAs share 3' common nucleotide sequences and they are transcribed in the same orientation as the proposed unspliced Rep RNA or the recently described Rep' RNA. The 35 kD capsid protein was observed at 30 h p.i. by Western blot analysis and it appeared to be the most immunodominant protein in swine exposed to PCV2. The capsid proteins of PCV type 1 and PCV2 each contain a nuclear localization signal sequence capable of targeting a reporter protein to the nucleoli of transfected cells when the capsid proteins were expressed as 3' fusion polypeptides. Although previous reports indicated that PCV2 capsid proteins localized predominantly in the nuclei of infected cells, we observed an abundant amount of PCV2 capsid proteins in the cytoplasm of many cells of the infected cultures. The cells that exhibited cytoplasmic capsid proteins also contained virus nucleic acids, indicating that these proteins were synthesized by the infected cells and not through uptake from the culture medium. Elucidation of the changes that affect the localization pattern of PCV2 capsid proteins, nuclear versus cytoplasmic, requires further investigation.

Animals↗

PubMed2001

Effect of indomethacin on peritoneal protein loss in a rabbit model of peritonitis.

BACKGROUND: Although various inflammatory mediators have been previously shown to be released into the peritoneal cavity during peritonitis in peritoneal dialysis patients, those that are involved in governing changes in peritoneal permeability to small solutes and protein remain incompletely defined. METHODS: We determined the importance of prostanoid production in the enhanced protein loss observed during acute peritonitis by inhibition experiments using indomethacin, an inhibitor of cyclooxygenase activity. The association between changes in peritoneal permeability and the generation of inflammatory mediators after adding Escherichia coli to peritoneal dialysate was first examined in series 1 experiments. Series 2 experiments then determined the effect of intraperitoneal administration of indomethacin (75 microg/mL) on changes in peritoneal permeability after adding E. coli to peritoneal dialysate. All experiments were performed in male New Zealand White rabbits (2.6 to 3.4 kg body weight) using an eight-hour dwell of dialysate containing 2.5% glucose. Peritoneal permeability to creatinine and protein was assessed by time-dependent changes in the dialysate to plasma concentration ratios of these solutes. RESULTS: Series 1 experiments showed enhanced leukocyte migration into the peritoneal cavity and increased peritoneal permeability to protein during bacterial challenge that was accompanied by an increase in the dialysate concentrations of prostaglandin E2 (PGE2), 6-keto-PGF1alpha, and interleukin-8, but not nitrate + nitrite (a measure of local nitric oxide production). Inhibition of prostanoid production by intraperitoneal administration of indomethacin in series 2 experiments resulted in lower dialysate concentrations of PGE2 and 6-keto-PGF1alpha and in lower peritoneal permeability to protein, both to control levels. No effect of indomethacin on transperitoneal migration of leukocytes or the generation of interleukin-8 was observed. CONCLUSIONS: Enhanced production of prostanoids likely plays an important role in governing the increase in peritoneal permeability to protein during acute, bacterial peritonitis in the rabbit.

6-Ketoprostaglandin F1 alpha↗

PubMed2001

Increases in mass transfer-area coefficients and urea Kt/V with increasing dialysate flow rate are greater for high-flux dialyzers.

The hemodialyzer mass transfer-area coefficient (K(o)A) for urea increases with increasing dialysate flow rate (Q(d)). The magnitude of the increase in K(o)A varies depending on the particular dialyzer under consideration; however, dialyzer properties that govern this phenomenon have not been established. We hypothesized that Q(d)-dependent increases in K(o)As are influenced by the water permeability of the dialysis membrane. We evaluated in vitro the effect of blood flow rate (Q(b)) and Q(d) on urea and creatinine K(o)As for two low-flux (Polyflux 6L and 8L) and two high-flux (Polyflux 14S and 17S) dialyzers containing Polyamide S membranes with similar membrane surface areas. Additional experiments were also performed on high-flux dialyzers containing Polyamide S membranes with very large surface areas (Polyflux 21S and 24S). K(o)As, calculated from the mean of blood- and dialysate-side clearances, were determined at zero net ultrafiltration for three different Q(b) and Q(d) combinations: Q(b) of 300 mL/min and Q(d) of 500 mL/min; Q(b) of 450 mL/min and Q(d) of 500 mL/min; and Q(b) of 450 mL/min and Q(d) of 800 mL/min. Urea and creatinine K(o)As were independent of the Q(b) but increased when Q(d) was increased from 500 to 800 mL/min. These increases in both urea and creatinine K(o)As were greater for high-flux than low-flux dialyzers (P < 0.0001). As expected, urea and creatinine K(o)As also increased with increasing membrane surface area. We conclude that dialysis membrane water permeability (or flux) is a dialyzer property that influences the dependence of small-solute K(o)As and clearance on Q(d). Whether this phenomenon is caused by enhanced internal filtration for dialyzers containing high-flux membranes requires further study.

Algorithms↗

PubMed2000

Pseudorabies virus induces apoptosis in tissue culture cells.

The process of cell death as a result of exposure to pseudorabies virus (PRV) in cultured cells was examined and specific features characteristic of apoptosis were observed. At early times of infection, externalization of membrane phospholipid phophatidylserine was detected by flow cytometry analysis. During the infection process, caspase 3-like protease activity was induced and the activity increased in a time dependent manner. Cellular DNA degradation was demonstrated by agarose gel electrophoresis. Morphologic changes of the nucleus that included chromatin condensation and margination to the periphery of the nucleus were evident in electron microscopy analysis. These biochemical and morphologic changes demonstrated that, during PRV replication, the host cell was induced to undergo apoptosis.

Animals↗

PubMed2000

Increased protein loss during peritonitis associated with peritoneal dialysis is neutrophil dependent.

BACKGROUND: Peritonitis in peritoneal dialysis patients is accompanied by an enhanced migration of neutrophils (PMNs) and increased protein loss into the peritoneal cavity; however, the role of PMNs in governing increased protein loss during peritonitis associated with peritoneal dialysis is unknown. METHODS: We determined the importance of PMNs in governing changes in peritoneal permeability to protein in New Zealand White rabbits in which acute peritonitis was induced by adding 4 x 106 colony-forming units of Escherichia coli to 35 mL/kg of 0.9% saline dialysate. The total leukocyte and PMN migration into the peritoneal cavity was assessed by differential cell counts in the dialysate, and peritoneal permeability to protein was evaluated by calculating the dialysate to plasma concentration ratio for total protein as a function of time during a six- or eight-hour dwell. In series 1 experiments, leukocytes were depleted from the rabbit circulation by an intravenous injection of mustine (1.2 mg/kg) three days before the experiment; in series 2 experiments, integrin-dependent PMN migration into the peritoneal cavity was inhibited by an intravenous injection of monoclonal antibody (mAb) 60.3 (2 mg/kg) directed against the integrin CD18 on leukocytes five minutes before the experiment. RESULTS: In series 1 experiments, mustine decreased circulating leukocytes by 82 +/- 5% (mean +/- SEM) and circulating PMNs by 93 +/- 3%. Total leukocyte and PMN migration into the peritoneal cavity and peritoneal permeability to protein were decreased in mustine-treated rabbits after exposure to E. coli in the dialysate to levels similar to those found in rabbits without bacterial peritonitis. In series 2 experiments, an intravenous injection of anti-CD18 antibody also abrogated both the enhanced PMN migration into the peritoneal cavity and the increased peritoneal permeability to protein after exposure to E. coli in the dialysate. CONCLUSIONS: PMN migration into the peritoneal cavity is integrin dependent. Increased protein loss during acute, gram-negative bacterial peritonitis in a rabbit model of peritoneal dialysis is PMN dependent.

Acute Disease↗

PubMed2000

Atherosclerotic cardiovascular disease risks in chronic hemodialysis patients.

BACKGROUND: Cardiovascular diseases are the most common causes of death among chronic hemodialysis patients, yet the risk factors for these events have not been well established. METHODS: In this cross-sectional study, we examined the relationship between several traditional cardiovascular disease risk factors and the presence or history of cardiovascular events in 936 hemodialysis patients enrolled in the baseline phase of the Hemodialysis Study sponsored by the U.S. National Institutes of Health. The adjusted odds ratios for each of the selected risk factors were estimated using a multivariable logistic regression model, controlling for the remaining risk factors, clinical center, and years on dialysis. RESULTS: Forty percent of the patients had coronary heart disease. Nineteen percent had cerebrovascular disease, and 23% had peripheral vascular disease. As expected, diabetes and smoking were strongly associated with cardiovascular diseases. Increasing age was also an important contributor, especially in the group less than 55 years and in nondiabetic patients. Black race was associated with a lower risk of cardiovascular diseases than non-blacks. Interestingly, neither serum total cholesterol nor predialysis systolic blood pressure was associated with coronary heart disease, cerebrovascular disease, or peripheral vascular disease. Further estimation of the coronary risks in our cohort using the Framingham coronary point score suggests that traditional risk factors are inadequate predictors of coronary heart disease in hemodialysis patients. CONCLUSIONS: Some of the traditional coronary risk factors in the general population appear to be also applicable to the hemodialysis population, while other factors did not correlate with atherosclerotic cardiovascular diseases in this cross-sectional study. Nontraditional risk factors, including the uremic milieu and perhaps the hemodialysis procedure itself, are likely to be contributory. Further studies are necessary to define the cardiovascular risk factors in order to devise preventive and interventional strategies for the chronic hemodialysis population.

Adult↗

PubMed2000

Cardiopulmonary events during hemodialysis: effects of dialysis membranes and dialysate buffers.

Adverse cardiac and pulmonary events are frequently observed during hemodialysis and contribute to significant morbidity and mortality. The temporal relationship between these events during the intradialytic period has not been well defined. To examine the event rate and timing of silent ischemia, cardiac ectopy, and hypoxemia, we conducted a prospective, single-blind, randomized study of 10 subjects undergoing maintenance hemodialysis with four contiguous combinations of dialysis membranes (cuprammonium or polysulfone) and dialysates (acetate or bicarbonate). The frequency of oxygen desaturation events peaked during the first 2 hours, whereas silent myocardial ischemia and supraventricular ectopies occurred more often in the later hours. Ventricular ectopy occurred steadily throughout the intradialytic period. The combination of acetate dialysis and cuprammonium membrane is associated with the most frequent events. We conclude that cardiopulmonary events can occur frequently during hemodialysis, and the frequency is dependent on the type of dialysis membrane and dialysate buffer used.

Acetates↗

PubMed2000

The effects of aprotonin on platelets in vitro using whole blood flow cytometry.

UNLABELLED: We sought to evaluate the effects of aprotinin on the number and function of the platelet glycoprotein (GP) IIb-IIIa receptor and on the expression of P-selectin in vitro in order to gain insight into the potential mechanisms involved in the platelet-protective action of aprotinin during cardiopulmonary bypass. Aprotinin at 50 to 200 kallikrein inhibiting units/mL decreased the expression of activated GP IIb-IIIa complex in response to adenosine diphosphate or thrombin receptor activator peptide 6 in a dose-dependent manner in both citrated and heparinized whole blood experiments. Aprotinin inhibited adenosine diphosphate-induced platelet aggregation, but it exhibited no effect on the expression of GP IIIa and P-selectin. These results indicate that aprotinin interferes with the platelet fibrinogen receptor function during pharmacological activation. Reduced aggregability and platelet adhesion to fibrinogen adsorbed to synthetic surfaces in the presence of aprotinin may prevent platelet consumption during clinical cardiopulmonary bypass. This in vitro study demonstrates that aprotinin decreases the agonist-induced expression of activated GP IIb-IIIa receptors that play a major role in platelet aggregation and adhesion to biomaterial surfaces. IMPLICATIONS: This in vitro study demonstrates that aprotinin decreases the agonist-induced expression of activated glycoprotein IIb-IIIa receptors that play a major role in platelet aggregation and adhesion to biomaterial surfaces.

Adenosine Diphosphate↗

PubMed2000

The effects of heparin, protamine, and heparinase 1 on platelets in vitro using whole blood flow cytometry.

UNLABELLED: The effects of heparinization and the reversal of heparin activity on platelet function after cardiopulmonary bypass have not been well defined. Flow cytometry has become a convenient and powerful technique for characterizing platelets. We examined the expression of a secretion marker (P-selectin) and an aggregation marker (activated fibrinogen receptor GP IIb-IIIa) on normal platelets in response to heparin, heparinase 1, and protamine in vitro using whole blood flow cytometry. Unfractionated heparin increased adenosine diphosphate-induced expression of P-selectin and GP IIb-IIIa in a dose-dependent manner. Heparinase 1 alone decreased both markers of platelet activation. Protamine alone increased P-selectin expression but had no effect on GP IIb-IIIa expression. Heparinase 1 antagonized the stimulatory effect of heparin on both markers. In contrast, protamine antagonized the effect of heparin on GP IIb-IIIa expression but potentiated the effect of heparin on P-selectin expression. These in vitro observations suggest that 1) both heparin and its reversal agents affect platelet secretion and aggregation, and 2) heparinase 1 reverses heparin-induced platelet preactivation more effectively than protamine. IMPLICATIONS: This experimental in vitro study demonstrates that heparin and its reversal agents affect platelet secretion and aggregation.

Adult↗

PubMed1999

Analysis of the latency-associated transcript/UL1-3.5 gene cluster promoter complex of pseudorabies virus.

During latency, pseudorabies virus (PRV) DNA is preferentially retained in the neurons of the trigeminal ganglion and a spliced 8.5-kilobase poly-A RNA, designated large latency transcript (LLT), is synthesized. Because LLT is the only transcript made during the latent phase, the LLT promoter may be unique among all other PRV promoters that are active in productive infections. Organization of the PRV LLT promoter is quite complex because it coincides with the UL1-3.5 gene cluster promoter, but in the opposite orientation. By conventional designation, LLT is transcribed in the rightward direction while the UL1-3.5 gene cluster is transcribed in the leftward orientation. In this work, activities of the LLT promoter and the UL1-3.5 gene cluster promoter were investigated by transient reporter gene expression assay in cells of neuronal and non-neuronal origins. There are two TATA boxes in this region. We examined the promoter activities of the first TATA box with its 5' sequence (LAP1) and the second TATA box with its 5' sequence (LAP2). The UL1-3.5 promoter driven constructs gave no reporter gene activity in any of the experiments. Reporter gene activity was detected with LAP2 gene constructs, but not with LAP1 constructs, in both neuronal and non-neuronal cells. This is surprising because transcription of PRV LLT in vivo has been attributed to LAP1 and the initiation site was mapped downstream of the LAP1 TATA box and upstream of the LAP2 TATA box. Although LAP1 was not active in these experiments, there was a 3- to 10-fold enhancement of activity when LAP1 and LAP2 were placed in tandem.

Animals↗

PubMed1999

Effect of dialysis membranes and middle molecule removal on chronic hemodialysis patient survival.

The type of dialysis membrane used for routine therapy has been recently shown to correlate with the survival of chronic hemodialysis patients. We examined whether this effect of dialysis membrane could be explained by differences in dialyzer removal of middle molecules using data from the 1991 Case Mix Adequacy Study of the United States Renal Data System. The sample analyzed included patients who had been treated by hemodialysis for 1 year or more, who were dialyzed with the 19 most commonly used dialyzers in 1991, and for whom delivered urea Kt/V could be calculated from predialysis and postdialysis blood urea nitrogen concentrations. Vitamin B12 (1,355 daltons) was used as a marker for middle molecules, and the clearance of vitamin B12 was estimated based on in vitro data. After adjustments for case mix, comorbidities, and urea Kt/V, the relative risk of mortality for a 10% higher calculated total cleared volume of vitamin B12 was 0.953 (P < 0.0001 v 1.000). Similar results were obtained when middle molecule removal was adjusted for body size. We conclude that both small and middle molecule removal indices appear to be independently associated with the risk of mortality in chronic hemodialysis patients. Differences in mortality when using different types of dialysis membrane may be explained by differences in middle molecule removal.

Humans↗

PubMed1999

Fibrinogen fragments and platelet dysfunction in uremia.

BACKGROUND: The uremic state is characterized by subnormal platelet aggregation. Fibrinogen fragments, usually absent in normal human blood, but present in uremic plasma, may play a role in uremic platelet dysfunction. METHODS: To examine this hypothesis, we investigated the availability and function of fibrinogen receptors [glycoprotein (GP) IIb-IIIa] on uremic and normal platelets, as well as the effect of fragments obtained from chymotrypsin digestion of human fibrinogen on normal platelets. The availability of fibrinogen receptors was examined using anti-GP IIb-IIIa antibodies and flow cytometry, whereas receptor function was assessed by the receptor's ability to mediate fibrinogen binding and platelet aggregation. RESULTS: Platelet aggregation and the availability of GP IIb-IIIa were lower in uremic patients when compared with normal controls. Flow cytometric analysis showed that fibrinogen fragments decreased the binding of anti-CD61, an activation-independent anti-GP IIIa monoclonal antibody, to resting normal platelets. These fragments also reduced the binding of PAC-1, an activation-dependent anti-GP IIb-IIIa monoclonal antibody, to adenosine diphosphate (ADP)-activated normal platelets. In addition, the binding of radiolabeled fibrinogen to activated normal platelets and platelet aggregation in response to ADP were both decreased by fibrinogen fragments. CONCLUSIONS: These findings suggest that fibrinogen fragments impair platelet function by occupying fibrinogen receptors prior to cell activation, thus preventing the binding of intact fibrinogen to platelets after subsequent stimulation. These observations also suggest a plausible mechanism by which endogenous fibrinogen fragments present in uremic plasma may contribute to platelet dysfunction.

Adenosine Diphosphate↗

PubMed1999

Peripheral donor leukocytes prolong survival of rat renal allografts.

BACKGROUND: The development of strategies to enhance the survival of transplanted organs and to potentially lower or even discontinue immunosuppressive therapy would represent a significant advancement in post-transplant patient care. METHODS: We studied the effect of pretransplant infusion of donor leukocytes alone or in combination with a short course of cyclosporine on the long-term outcome of a rat model of kidney allograft. RESULTS: A single intravenous infusion of donor peripheral blood leukocytes (100x10(6) cells) from Brown-Norway (BN) rats into major histocompatibility complex (MHC) incompatible Lewis recipients largely failed to prolong kidney allograft viability from the same donor transplanted 60, 40, or 30 days after cell infusion. A short course of cyclosporine (per se, unable to prolong graft survival) was started at the same day of donor leukocyte infusion, but instead was able to prolong the survival of the BN kidney transplant-performed 40 days later-but not of a Wistar Furth (WF) third party, with some animals even developing tolerance. A mixed lymphocyte reaction of host cells from long-term surviving rats to BN stimulator cells was significantly reduced as compared with controls. Donor BN DNA was detected in the peripheral blood of Lewis rats until day 40 after BN leukocyte infusion. Microchimerism persisted (60 to 70 days post-transplant) in most long-term graft recipients. Reducing the time interval between donor leukocyte infusion and subsequent kidney transplant to 10 days still prolonged graft survival. Donor peripheral blood mononuclear cells, but not polymorphonuclear cells, in the leukocyte preparation contributed to prolong kidney allograft survival. CONCLUSIONS: Pretransplant donor leukocyte infusion under the appropriate conditions can tip the immune balance toward improved graft acceptance. This result could be relevant to the achievement of donor-specific tolerance of the graft with the maintenance of an intact response to third-party antigens.

Animals↗

PubMed1999

Rebound kinetics of beta2-microglobulin after hemodialysis.

BACKGROUND: Evaluation of beta2-microglobulin (beta2m) removal during hemodialysis using predialysis and immediate postdialysis plasma concentrations is only valid in the absence of postdialysis rebound. Postdialysis rebound of beta2m has not been studied extensively, and its importance in the determination of beta2m clearance is unknown. METHODS: We evaluated the kinetics of urea and beta2m in a crossover study of 10 chronic hemodialysis patients using dialyzers with similar urea mass transfer-area coefficients containing either low-flux cellulose acetate or high-flux cellulose triacetate membranes. Kinetics were examined during and following a 210 minute treatment by measuring plasma concentrations predialysis at regular intervals during therapy and at 0, 2, 10, 20, 30, and 60 minutes postdialysis. Clearances of urea and beta2m were also determined directly from the arterial and venous concentration differences across the dialyzer at 60 minutes after starting dialysis. RESULTS: By design, urea removal was similar for both low-flux and high-flux dialyzers as assessed by the urea reduction ratio and Kt/V. Postdialysis urea rebound was similar for low- and high-flux dialyzers; the rebound in the plasma urea nitrogen concentration (expressed as a percentage of the intradialytic decrease in plasma concentration) was 9.2 +/- 1.9% (mean +/- SEM) at 30 minutes postdialysis and 13.0 +/- 1.4% at 60 minutes postdialysis for a single pool urea Kt/V of 1.16 +/- 0.05. The plasma beta2m concentration increased by 11.1 +/- 3.0% during the treatment using the low-flux dialyzer but decreased by 27.1 +/- 4.0% during the treatment using the high-flux dialyzer. When using the high-flux dialyzer, the rebound of beta2m was 44.8 +/- 21.4% at 30 minute postdialysis and 45.9 +/- 15.9% at 60 minutes postdialysis. The clearance of beta2m for the high-flux dialyzer calculated from predialysis and immediate postdialysis plasma concentrations using a single-compartment model (28.2 +/- 4.4 ml/min) was higher (P < 0.05) than that determined directly across the dialyzer (18.3 +/- 2.0 ml/min). If either the 30- or 60-minute postdialysis plasma beta2m concentration was used instead, the calculated beta2m clearance (16. 5 +/- 4.8 ml/min or 15.6 +/- 2.8 ml/min, respectively) was similar to that determined directly across the dialyzer. CONCLUSIONS: Postdialysis rebound of beta2m when using high-flux dialyzers is substantial; neglecting postdialysis rebound results in an overestimation of beta2m clearance when calculated using a single-compartment model.

Adult↗

PubMed1999

Effect of permeability on indices of haemodialysis membrane biocompatibility.

BACKGROUND: Increases in plasma anaphylatoxins frequently are used as an index of haemodialysis membrane biocompatibility; however, their plasma levels may be influenced by the loss of anaphylatoxins into the dialysate compartment. METHODS: We compared the generation and compartmental distribution of anaphylatoxins, C3a and C5a, in a high flux and a low flux polysulfone membrane dialyser when whole human blood was recirculated through an in vitro haemodialysis circuit. RESULTS: Plasma C3a levels in high flux polysulfone (2.31 +/- 0.81 microg/ml) and low flux polysulfone (3.02 +/- 0.98 microg/ml) dialysers were comparable after 120 min (P = NS). In contrast, dialysate C3a in high flux polysulfone (0.65 +/- 0.31 microg/ml) accounted for 37.5 +/- 7.0% of the total detected (plasma + dialysate) C3a mass in the dialysers, while dialysate C3a in low flux polysulfone dialysers (0.01 +/- 0.01 microg/ml) accounted for only 0.3 +/- 0.3% of the total mass (P < 0.05; high flux vs low flux). Anaphylatoxin C5a was undetectable in the dialysate compartment of either dialyser examined. CONCLUSIONS: Our results indicate that anaphylatoxins readily traverse certain high flux dialysis membranes; consequently, plasma C3a levels may not accurately reflect the C3-activating potential of these membranes.

Biocompatible Materials↗

PubMed1999

Effects of hemodialyzer reuse on clearances of urea and beta2-microglobulin. The Hemodialysis (HEMO) Study Group.

Although dialyzer reuse in chronic hemodialysis patients is commonly practiced in the United States, performance of reused dialyzers has not been extensively and critically evaluated. The present study analyzes data extracted from a multicenter clinical trial (the HEMO Study) and examines the effect of reuse on urea and beta2-microglobulin (beta2M) clearance by low-flux and high-flux dialyzers reprocessed with various germicides. The dialyzers evaluated contained either modified cellulosic or polysulfone membranes, whereas the germicides examined included peroxyacetic acid/acetic acid/hydrogen peroxide combination (Renalin), bleach in conjunction with formaldehyde, glutaraldehyde or Renalin, and heated citric acid. Clearance of beta2M decreased, remained unchanged, or increased substantially with reuse, depending on both the membrane material and the reprocessing technique. In contrast, urea clearance decreased only slightly (approximately 1 to 2% per 10 reuses), albeit statistically significantly with reuse, regardless of the porosity of the membrane and reprocessing method. Inasmuch as patient survival in the chronic hemodialysis population is influenced by clearances of small solutes and middle molecules, precise knowledge of the membrane material and reprocessing technique is important for the prescription of hemodialysis in centers practicing reuse.

Acetic Acid↗

PubMed1998

Herpes simplex virus type 1 ICP-0 induces reactivation of pseudorabies virus from latently infected trigeminal ganglia explant cultures.

Pseudorabies virus (PrV), like other alphaherpesviruses, is a neurotropic virus that can establish a latent infection in swine. Reactivation of PrV from latency may occur spontaneously or after induction with corticosteroids. The mechanisms involved in the establishment of latency and reactivation are currently unknown. Here, we examined gene-specific reactivation of PrV by herpes simplex virus type 1 (HSV-1) immediate early protein, ICP-0. Primary neuronal cell cultures established from the trigeminal ganglia of latently infected swine were superinfected with recombinant adenoviruses expressing ICP-0. Reactivation of PrV occurred in cultures that were superinfected with two different ICP-0-expressing adenovirus recombinants, but not in cultures that were either mock-infected, or superinfected with wild-type adenovirus, or recombinant adenoviruses not expressing ICP-0. Infectious PrV was detected between 4 and 7 days postinfection, regardless of the promoter driving expression of ICP-0. Results from these experiments show that HSV-1 ICP-0, a homologue of PrV EP0, can induce PrV reactivation from explanted trigeminal ganglia of latently infected swine.

Animals↗

PubMed1998

Evaluating volume status in hemodialysis patients.

Accurate determination of the volume and distribution of body fluids in end stage renal disease patients will permit improved assessment of dry weight and strategies for optimal fluid removal. Certain biochemical markers and anatomical measures have been proposed as markers of dry weight, but these markers primarily reflect the volume of the intravascular compartment and may not reflect total body volume status. Noninvasive determination of total body water and extracellular fluid volumes using bioimpedance analyses has also been proposed for assessment of dry weight, but such determinations do not yet have sufficient accuracy for routine use. Several devices have been recently developed for continuously monitoring changes in blood volume on-line during routine hemodialysis. Such blood volume monitors cannot be used to determine dry weight directly; however, continuous monitoring of blood volume can be used to detect fluid overload because intradialytic changes in blood volume are small in hemodialysis patients who are overhydrated. Furthermore, continuous monitoring of blood volume can be used to predict symptoms resulting from intradialytic hypovolemia. The combined use of blood volume monitoring and time-dependent ultrafiltration and dialysate sodium profiles will be used increasingly in the future to assist in the prevention of hypotension and symptoms that result from intradialytic hypovolemia, especially when automated systems for controlling intradialytic blood volume are individualized and shown to be safe and effective.

Blood Volume↗