Immobilization of uricase enzyme on self-assembled gold nanoparticles for application in uric acid biosensor

An enzyme immobilization matrix is described by preparing a self-assembly of gold nanoparticles (GNPs) over a self-assembled monolayer (SAM) of 3-aminopropyltriethoxysilane (APTES) on an indium-tin-oxide (ITO) coated glass plate. The surface of the GNPs was modified with a mixed (1:9) SAM of 11-mercaptoundecanoic acid (MUA) and 3-mercapto-propionic acid (MPA). The enzyme, uricase was covalently immobilized to the carboxyl groups of the mixed SAM of MUA/MPA through carbodiimide coupling reaction. The whole assembly was constructed on 1 cm2 area of ITO-glass plate and was tested as an amperometric biosensor for the detection of uric acid in aqueous solution. The biosensor assembly was characterized by atomic force microscopy (AFM) and electrochemical techniques. The AFM of the enzyme biosensor assembly reveals an asymmetrical sharp regular island-like structure with an average roughness parameter value of 2.81 nm. Chronoamperometric response was measured as a function of uric acid concentration in aqueous solution (pH 7.4), which exhibits a linear response over a concentration range of 0.07 to 0.63 mM with a sensitivity of 19.27 microAmM(-1) and a response of 25 s with excellent reproducibility. These results are not influenced by the presence of interfering reagents such as ascorbic acid, urea and glucose. GNPs-biomolecule assemblies constructed using this method may facilitate development of new hybrid biosensing materials.

Impact of hepatitis C virus infection and other comorbidities on survival in patients on dialysis

The impact of hepatitis C virus (HCV) and other comorbid conditions upon survival is not well quantified in patients on dialysis. We identified HCV-infected and uninfected persons in the USRDS using claims data in 1997-1998 and followed until September 22, 2002 or death. We used Gray's time-varying coefficients model to examine factors associated with survival. Subjects with a renal transplant were excluded. A total of 5737 HCV-infected and 11 228 HCV-uninfected persons were identified. HCV-infected subjects were younger (mean age 57.8 vs 65.3 years), more likely to be male (57.6%vs 49.6%) and black (54.0%vs 36.4%). They were more likely to have a diagnosis of drug (16.5%vs 4.6%) and alcohol use (14.0%vs 3.1%), and to be human immunodeficiency virus (HIV) co-infected (7.4%vs 1.8%) (all comparisons, P < 0.0005). In an adjusted Gray's time-varying coefficient model, HCV was associated with an increased risk of mortality (P < 0.0005). The hazards were highest at the time of HCV diagnosis and decreased to a stable level 2 years after diagnosis. Other factors associated with increased risk of mortality were (P < 0.0005 unless stated) HIV coinfection; diagnosis of drug use (P = 0.001); coronary artery disease (P = 0.006); stroke; diabetes as the primary cause for renal failure; peripheral vascular disease; depression and presence of anaemia. HCV was associated with higher risk of death in patients on dialysis, even after adjusting for concurrent comorbidities. The risk was highest at the time of HCV diagnosis and stabilized over time. Clinical trials of HCV screening and treatment to reduce mortality in this population are warranted.

Growth of intramedullary lipoma in a renal transplant recipient

BACKGROUND

Administration of glucocorticoids can lead to a variety of complications in addition to deposition of fat leading to cushingoid features. Corticosteroids, either endogenously produced or exogenously administered, are implicated in the growth of lipomas in different anatomic locations including the epidural space in the spinal cord causing cord compression.

METHOD

We report a growth of lipoma in an unusual site in a 28-year-old female renal transplant recipient within 6 weeks of renal transplant surgery.

RESULT

Our patient had an intradural lipoma that had merged with the medulla of the spinal cord making its total excision unfeasible without damaging the spinal cord.

CONCLUSION

Epidural lipomas causing cord compression is documented in patients receiving long-term corticosteroid therapy. This is the first case of intramedullary lipoma of the spinal cord that may be related to steroid use.

Laboratory abnormalities in patients with bacterial pneumonia

STUDY OBJECTIVES

This study was undertaken to evaluate the laboratory abnormalities observed in patients with bacterial pneumonia as predictors of the severity of illness.

DESIGN

Retrospective analysis.

SETTING

Tertiary care hospital.

PATIENTS AND PARTICIPANTS

We studied 302 consecutive patients who were admitted to the Long Island Jewish Medical Center from January through December 1993 and treated for bacterial pneumonia. The patients were subdivided into two groups based on their serum phosphorus level either on hospital admission or 4 days before the onset of pneumonia, if this was acquired in-hospital. Hypophosphatemia (group 1) was defined as serum phosphorus level of < or = 2.4 mg/dL and normophosphatemia > 2.4 mg/dL (group 2). Three hundred randomly selected hospitalized patients treated for conditions other than pneumonia comprised the control group (group 3).

MEASUREMENTS

Groups 1 and 2 were compared with respect to laboratory data, mortality rate, and duration of hospitalization. The laboratory data of patients in group 3 were compared with those treated for bacterial pneumonia (groups 1 and 2). Stepwise multivariate logistic regression analysis was employed to identify the variables that best predicted the onset of pneumonia.

RESULTS

In groups 1 and 2, a greater (p < 0.0001) number of patients (135 of 302 patients with pneumonia, 44.7%) developed hypophosphatemia compared with patients in group 3 (31 of 300 control subjects, 10.3%). Patients with pneumonia (groups 1 and 2) had higher levels (p < 0.01) of bicarbonate compared with control subjects. Moreover, patients with pneumonia demonstrated lower levels (p < 0.01) of calcium, phosphorus, albumin, cholesterol, and alanine aminotransferase compared with control patients (group 3). Among patients with pneumonia, those with hypophosphatemia (group 1) had significantly lower levels (p < 0.05) of potassium, calcium, and albumin compared to those subjects with normophosphatemia (group 2). Furthermore, hypophosphatemic subjects manifested higher levels of glucose (p < 0.01) and creatine phosphokinase (p < 0.05) compared to their normophosphatemic counterparts. In addition, hypophosphatemic patients experienced a longer duration of hospital stay (hypophosphatemia, 24.6 +/- 2.0 days, vs normophosphatemia, 14.1 +/- 1.0, p < 0.001) and higher (p < 0.001) mortality compared to normophosphatemic subjects. The incidence of nosocomial pneumonia was higher (p < 0.0001) in hypophosphatemic patients compared to those with normophosphatemia.

CONCLUSION

We conclude that hypophosphatemia, hypocalcemia, hypokalemia, and hypoalbuminemia may be predictors of the severity of illness in patients admitted to the hospital with bacterial pneumonia.