A retrospective analysis of the factors associated with hypercalcaemia in patients with advanced cancer

Hypercalcaemia, a common complication of advanced cancer, causes multiple clinical symptoms, deteriorates patients' quality of life, and is associated with poor prognoses. This study aimed to identify the factors that may be associated with hypercalcaemia in advanced cancer by retrospectively reviewing the medical records of patients (n = 404) admitted to the palliative ward of the Kaohsiung Medical University Hospital, Taiwan, from 2006 to 2008. Patients' demographics, clinical data and symptoms were recorded. Seventy-nine of 404 patients had hypercalcaemia (19.6%), predominant in cases of head-and-neck cancer and haematological malignancies (P < 0.05), but not in those of bone metastases. Hypercalcaemia was associated with consciousness disturbances and leucocytosis (P < 0.05). We recommend that ionised (corrected) calcium levels be monitored clinically in patients with advanced cancer especially when consciousness disturbances are noted, or when head-and-neck or haematological malignancies are present. Testing of free calcium levels is also recommended in patients with leucocytosis.

Can we reduce the cardiovascular risk in peritoneal dialysis patients?

Patients with end-stage renal disease (ESRD), including those treated with peritoneal dialysis (PD), have a high risk for death, particularly from cardiovascular (CV) causes. Traditional risk factors for CV disease – like hypertension, diabetes, and dyslipidemia - are highly prevalent, often severe, and more difficult to treat in dialysis patients. Development of strategies for CV risk reduction in dialysis patients is complicated by epidemiologic studies that demonstrate paradoxical associations of some of the traditional risk factors with mortality. The difficulty is enhanced by either a paucity or negative findings of studies that have tested risk modification by targeting traditional CV risk factors. It is also clear that neither the prevalence nor the severity of traditional risk factors explains the substantial increase in risk for death associated with ESRD; this has led to identification of several nontraditional risk factors. Among these, systemic inflammation, disordered mineral metabolism, and long-term CV risk from infectious complications appear the most promising. However, the evidence in favor of the importance of these risk factors is largely limited to observational studies. In this review, we present a critical analysis of the literature to assist the clinician to reduce the CV risk of ESRD patients treated with PD.

Selective binding of polychlorinated biphenyl congeners by a monoclonal antibody: analysis by kinetic exclusion fluorescence immunoassay

A previously described monoclonal antibody, S2B1, was highly selective for coplanar (non-ortho-chlorinated) PCB congeners in enzyme immunoassays that measured binding at equilibrium. In the present study, kinetic exclusion fluoroimmunoassay (KinExA) was used to determine the dissociation constants (Kd) and on and off rates (k(on), k(off)) for binding of various PCB congeners to affinity-purified S2B1 IgG and Fab fragments in solution. This method revealed that mono- and di-ortho-chlorinated PCBs were bound by S2B1, but the on rates were slower, and the off rates faster by 6-60-fold, than with congeners that had no ortho chlorines. Although the sensitivity of immunoassays may be improved by using competing haptens that S2B1 binds more weakly than the parent PCB, the KinExA results demonstrate that congener specificity is an intrinsic property of S2B1 and does not require weaker binding haptens. KinExA also provided new information on the percentage of active binding sites, valence, and effects of buffer, solvent, and biotinylation on S2B1. The advantages and drawbacks of KinExA for measuring antibody-ligand binding are described.

Derivation and properties of recombinant Fab antibodies to coplanar polychlorinated biphenyls

Recombinant Fab antibodies (rFabs) specific for coplanar polychlorinated biphenyls (PCBs) were derived from a hybridoma cell line (Chiu et al. Anal. Chem. 1995, 67, 3829-3839). Immunoglobulin V(H)-C(H1) and V(L)-C(L) sequences from S2B1 messenger RNA were amplified by PCR and cloned into the M13 phagemid vector pComb3H. Phage displaying rFab were enriched by panning on a PCB hapten conjugate and expressed as soluble rFabs in Escherichia coli XL-1 Blue. Two rFab clones competitively bound PCBs 77 and 126 with half-maximal inhibition (I(50)) of 10-13 ppb in indirect and direct enzyme immunoassays (EIAs), with selectivity nearly identical to that of whole S2B1 IgG and its Fab fragments prepared by papain digestion. These results, and comparison of N-terminal amino acid sequences of MAb S2B1 and the rFab, indicated that rFab S2B1 is a functional copy of the MAb. The rFab S2B1 sequences have 75-89% sequence identity with antibodies that bind nitrophenyl haptens and are being used to construct a three-dimensional computational model of the PCB binding site.

A monoclonal immunoassay for the coplanar polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants with diverse toxic, teratogenic, reproductive, immunotoxic, and tumorigenic effects. Three of the least abundant of the 209 PCB isomers (congeners) are the most toxic and most difficult to quantify. These are 3,4,3',4'-tetrachlorobiphenyl, 3,4,3',4',5'-pentachlorobiphenyl, and 3,4,5,3',4',5'-hexachlorobiphenyl (IU-PAC No. 77, 126, and 169, respectively). An immunizing hapten was designed to retain the 3,4,3',4' chlorine-substitution pattern and coplanarity characteristic of these toxic congeners. The optimal competitors for immunoassay were weaker binding distinctive single-ring fragments of the PCBs. A monoclonal antibody designated S2B1 was derived and used in direct (antibody-capture) competitive enzyme immunoassays (EIAs). The EIAs are highly specific for non-ortho-substituted congeners and do not recognize the more prevalent but much less toxic noncoplanar PCB congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, or dichlorobenzenes. Hapten and competitor design for this assay suggests a basis for development of sensitive EIAs for other classes of PCB congeners.

Blood content in guinea-pig tissues: correction for the study of drug tissue distribution

The blood content in different organs or tissues of guinea-pigs was determined by means of [125I]bovine serum albumin. The blood distribution expressed as percentage of total body blood for various organs or tissues ranged from 0.35 (adipose) to 17.5 (muscle)%. The blood content in tissue preparations expressed as the blood background correction factor, F (ml blood/g wet tissue) depended on the extent of bleeding during experiment; that factor can cause a considerable difference in the results of a tissue distribution study of a drug. Blood content was high in the lung (0.36 ml/g), heart, liver, kidney and spleen, but low in adipose and brain tissues (0.021 ml/g). The distribution of valproic acid in various tissues of guinea-pigs after intravenous injection was determined from the homogenates of isolated organs. The results showed that blood contamination can greatly alter the data of tissue distribution of a drug to as much as 25%. This study proposed a maximum (non-bled) and a minimum (extreme-bled) blood background correction factor for respective tissues of guinea-pigs, as well as equations for correcting the blood contamination in tissue during the drug distribution study. The results suggest that to obtain an exact analysis of drug concentrations in specific tissues, a correction for the blood of that specific tissue is necessary.