Improving evidence developed from population-level experience with targeted agents.

Off-label drug use is common in oncology, due in part to significant unmet medical need, the rarity of many cancers, and the difficulty of conducting randomized controlled trials (RCTs) to support labeling of every drug in every disease setting. As new drugs are developed for use in tumors defined by genomic aberrations, it may be scientifically reasonable to expect that a targeted anti-cancer agent with efficacy in a biomarker-defined population within one tumor type may also have activity in another tumor type expressing the same biomarker. Such expectations also fuel off-label prescribing. However, the current approach to prescribing targeted agents off-label does not capture patient outcomes, thus missing an opportunity to gather data that could validate this approach. We explore the potential for collecting such data, highlight two proposals for oncology-specific patient registries, and put forward considerations that should be addressed to move toward better evidence development around off-label use.

High-resolution spatial analysis of stomatal ozone uptake in arable crops and pastures.

Ozone effects on plants depend on atmospheric transport and stomatal uptake. Thus, ozone-risk assessments should use measured ozone concentrations and account for the influence of atmospheric conditions and soil moisture on stomatal and nonstomatal ozone deposition. This requires disaggregated data for the physical input parameters and species-specific data for specific stomatal conductance (g(s)). In this study, an approach was developed based on a resistance analogue transport model. This model requires interpolated routine-measuring data for ozone concentration at 3-5 m height, wind speed, precipitation, and soil moisture content as inputs to estimate the amount of ozone taken up by wheat (Triticum aestivum) and grass/clover pastures with a 1x1-km resolution. The model was applied to the area under agricultural production in Switzerland. Using data for June 1994, the calculations revealed that the median of the distribution of stomatal ozone uptake was 88% higher in wheat compared to grassland. This was mainly due to the higher maximum stomatal conductance in wheat. Because ozone flux to soil and to external plant surfaces was comparable in both vegetation types, the difference in the stomatal fluxes was mainly responsible for distinct differences in flux partitioning. In both cases, only about 11% of the total cumulative flux was absorbed by external plant surfaces, whereas the soil was a strong sink responsible for as much as 50% of the total flux into grasslands. The higher-ozone flux to wheat resulted in clearly lower-ozone concentrations at canopy height, but no significant correlation between cumulative canopy-level ozone exposure, expressed as accumulated exposure above 40 ppb (AOT40), and stomatal uptake was found. Thus, to estimate the ozone risk for crops using a flux-based approach may lead to results that differ substantially from those obtained with a concentration-based approach.

Creating a sustainable physician compensation plan. Serving both fee-for-service and capitated populations.

A large, integrated health system in St. Louis acquired a primary care, health maintenance organization staff model group practice with 55 physicians. Health system leadership positioned the acquired physician group to diversify and expand its fee-for-service patient base to increase revenue and support the expansive fixed cost structure of the health centers. With interim managers, the leaders developed a new physician compensation plan that put a greater portion of the physicians' compensation at risk and provided incentives for enhanced productivity in both the capitated and fee-for-service lines of business. This article explores the key characteristics, benefits and potential areas for improvement associated with the new incentive compensation model and describes the centers' improved operating performance and gains in physician productivity.

The gastrointestinal system and bowel management following spinal cord injury.

Gastrointestinal system changes following spinal cord injury (SCI) are generally less obvious than other body system changes. These alterations in function and the response to management, however, may have profound implications on the social, emotional, and physical well-being of the individual with SCI. This article reviews changes in gastrointestinal function following SCI and discusses current issues related to the management of the neurogenic bowel.

Difference in ozone uptake in grassland species between open-top chambers and ambient air.

Exposure-response data from open-top chamber (OTC) experiments are often directly applied to ambient air (AA) conditions. Because microclimatic conditions are modified and pollutant uptake by plants may differ (i.e. 'chamber effect'), there is concern about the influence of OTCs on these relationships. In addition, AA concentrations are often measured at a height which differs from canopy height and correction for the concentration gradient (i.e. 'gradient effect') is necessary. To quantify the relative contribution of plant characteristics and microclimatic factors to these effects, ozone uptake by horizontal leaves at the top of the canopy was calculated for plants grown in OTCs or AA by using a resistance analogy model. Data from an OTC experiment in 1996/97 for six species typical of productive grasslands were used. Ozone concentration inside OTCs was set equal to the concentration measured at a height of 3 m above ground (C(z(ref))) or at canopy height (C(0)). The gradient effect resulted in a 16-27% lower average C(0) than C(z(ref)), depending on species. The main determinant of the chamber effect was a systematic difference in leaf-to-air vapour pressure deficit between OTCs and AA which affected stomatal resistance and ozone uptake. In case of monocultures both effects were species-specific. In species mixtures the gradient effect differed between mixing ratios, whereas the chamber effect was species-specific. Because of the inter-specific difference in the chamber effect on ozone uptake, it is concluded that ozone effects on species mixtures differ systematically between OTCs and AA. The data underline that extrapolation of ozone flux-response relationships from OTC experiments must be based on canopy-level ozone concentrations, and that these relationships should be applied only to single species under microclimatic conditions similar to those prevailing in the experiment.

Technical performance of the Elecsys CA 72-4 test--development and field study.

Tumor-associated glycoprotein (TAG) 72 is a mucin-like protein of high molecular weight (220-400 kd). Elevated serum levels of TAG72 are preferentially observed in patients suffering from gastric cancer. Additionally the determination of TAG72 may be a helpful tool in the management of patients suffering from mucinous ovarian cancer, in whom the clinical sensitivity of CA125 is low. The new Elecsys CA72-4 assay-available as Elecsys 2010 and 1010--was evaluated in a first field study. The test has a wide measuring range (300 U/ml) and low detection limit (0.5 U/ml) which favours its routine use. Typical precision values are 2% for intra-assay, 4% for inter-assay and 6% for inter-instrument-precision. Method comparisons to Enzymun-Test CA72-4 showed a correlation between 0.91 and 0.96. The correlation to a commercially available RIA was 0.8. With human ascites material no Hook-effect was observed up to 20,000 U/ml. No Hama-interference with clinically relevant HAMA-samples was detected.

Human anti-mouse antibodies: pitfalls in tumor marker measurement and strategies for enhanced assay robustness; including results with Elecsys CEA.

Therapies using monoclonal antibodies may have undesirable consequences for the diagnostic use of tumor markers. These effects can be minimised by employing chimeric antibodies as well as special interference eliminating reagents. Human Anti-Mouse Antibodies (HAMA) are produced as a result of the immune response of a patient to treatment with murine monoclonal antibodies. The interaction of HAMA with the murine monoclonal antibodies of a tumor marker assay can simulate (false) positive or negative results leading to misdiagnosis and to inadequate disease management of a patient. To avoid HAMA-interferences "Roche Diagnostics" established a three-component-system: The use of chimeric antibodies, the interference elimination, which is realised in the parameters most frequently used like CEA and TSH. By employing such a chimeric antibody, Elecsys CEA proved to be extremely robust against HAMA-interferences. With 20 clinical relevant samples from different Mab-approaches, no HAMA-interference was observed. By fragmentation of the antibodies, i.e., elimination of the constant region and using monovalent fab-fragments (antigen binding fragment) combined with the addition of special blocking reagents all not-chimerized, Elecsys assays showed comparable results to chimerisation. This could also be shown with 20 clinical relevant samples.

Pulmonary function testing in spinal cord injury: correlation with vital capacity.

Spinal cord injury (SCI) causes restrictive ventilatory changes, with reductions in vital capacity, functional residual capacity, and expiratory reserve volume. Vital capacity (VC) often is used as an indicator of overall pulmonary function in these patients. In an effort to determine the extent to which VC correlates with other pulmonary function tests, 52 patients with recent acute traumatic SCI underwent complete pulmonary function testing. Statistical relationships were determined between VC and nine other tests. VC was found to be significantly correlated with forced expiratory volume in 1 s, inspiratory capacity, expiratory reserve volume, functional residual capacity, residual volume (RV), total lung capacity (TLC), and RV/TLC ratio, but not with maximum positive expiratory pressure nor with maximum negative inspiratory pressure. The excellent correlations between vital capacity and nearly all of the other pulmonary function tests support the use of VC as a single global measure of overall ventilatory status in SCI patients.

Parathyroid hormone (PTH)-PTH-related peptide hybrid peptides reveal functional interactions between the 1-14 and 15-34 domains of the ligand.

Parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP) bind to a common PTH/PTHrP receptor. To explore structure-function relations in these ligands, we synthesized and functionally evaluated PTH-PTHrP hybrid peptides in which the homologous 1-14 portions were exchanged. Hybrid-2, PTH-(1-14)-PTHrP-(15-34)NH2, bound to LLC-PK1 cells expressing the cloned rat PTH/PTHrP receptor with high affinity (IC50 approximately equal to 7 nM). In contrast, hybrid-1, PTHrP-(1-14)-PTH-(15-34)NH2, bound with much weaker affinity (IC50 approximately equal to 8,700 nM). Thus, the 1-14 region of PTHrP is incompatible with the 15-34 region of PTH. The carboxyl-terminal incompatibility site was identified as residues 19-21 (Glu-Arg-Val in PTH and Arg-Arg-Arg in PTHrP); extending the amino-terminal PTHrP sequence to residue 21 but not to 18 cured the hybrid's binding defect. The amino-terminal incompatibility site was identified as position 5 (Ile in PTH and His in PTHrP), because Ile5-hybrid-1 bound with high affinity (IC50 approximately equal to 20 nM). The importance of these identified residues in the native ligands was established by evaluating the effects of substitutions at these sites in a series of PTH and PTHrP analog peptides. Overall, the results are consistent with the hypothesis that, in both PTH and PTHrP, the 1-14 and 15-34 domains interact when binding to the receptor and that residues 5, 19, and 21 contribute either directly or indirectly to this interaction.

Role of the extracellular regions of the parathyroid hormone (PTH)/PTH-related peptide receptor in hormone binding.

The PTH/PTH-related peptide receptor is a member of a newly discovered family of G-protein-coupled receptors. Strikingly conserved features among these receptors include the positioning of eight extracellular cysteines and several other residues that are located predominantly within the membrane-embedded region. Deletion mutants or receptors with point mutations of the highly conserved cysteine residues were transiently expressed in COS-7 cells to evaluate PTH binding and PTH-stimulated cAMP production. Deletion of residues 61-105, which are encoded by exon E2 in the PTH/PTH-related peptide receptor gene, did not affect receptor function. An epitope derived from Haemophilus influenza hemagglutinin was, therefore, introduced into this portion of most receptors to allow the independent assessment of cell surface expression. PTH binding capacity was not reduced by the deletion of residues 258-278 in the first extracellular loop. Receptors with deletion of either residues 31-47 in the amino-terminal extension or residues 431-440 in the third extracellular loop failed to bind PTH, although expression of the receptor on the cell surface was only marginally reduced. Most other receptor mutants, including those in which each of the six cysteines in the amino-terminus was replaced by serines, failed to be processed and/or expressed appropriately, whereas the substitution of cysteine-281 or -351 had a less severe effect. The combined replacement of both cysteines concomitantly increased PTH binding and cell surface expression, suggesting the formation of a disulfide bond between these two residues. Our data indicate that residues near the amino-terminus and within the third extracellular loop are necessary for ligand binding, whereas more than 25% of the receptor's extracellular region appears not to be involved.

Determinants of [Arg2]PTH-(1-34) binding and signaling in the transmembrane region of the parathyroid hormone receptor.

Previously, we reported that [Arg2]PTH-(1-34) bound to the rat osteosarcoma cell line, ROS 17/2.8, with 2-fold higher apparent affinity than it did to the opossum kidney cell line, OK, yet the analog was only a weak partial agonist for cAMP stimulation with ROS 17/2.8 cells, whereas it was a full cAMP agonist with OK cells. These results suggested that the rat and opossum PTH receptors differ in a region recognized by the hormone's amino-terminus. In this report we show that the cloned PTH receptors derived from ROS 17/2.8 and OK cells, expressed in COS-7 cells, also displayed altered responses to [Arg2]PTH-(1-34). Thus, [Arg2]PTH-(1-34) bound to the cloned rat PTH receptor with 7-fold higher affinity than it did to the cloned opossum PTH receptor, and in cAMP stimulation assays, it was a much weaker agonist with the rat receptor than it was with the opossum receptor. Studies with rat/opossum PTH receptor chimeras suggested that the membrane-spanning region of the receptor contributed to the different binding and signaling responses to [Arg2]PTH-(1-34). Point mutation analysis identified three sites in or near the extracellular ends of transmembrane domains V and VI, which specifically affected [Arg2]PTH-(1-34) binding and signaling.

Ultrafilterable hypomagnesemia in neonates admitted to the neonatal intensive care unit.

OBJECTIVE: To evaluate the frequency and clinical correlates of ultrafilterable hypomagnesemia in neonates admitted to the neonatal intensive care unit (ICU). DESIGN: Prospective, observational study. SETTING: Massachusetts General Hospital and Mount Auburn Hospital. PATIENTS: A total of 117 patients (84 neonatal ICU patients and 33 normal newborns) studied over a 2-yr period of time. MEASUREMENTS: Blood samples were collected during the first 48 hrs after admission. The concentrations of magnesium (total and ultrafilterable), ionized calcium, parathyroid hormone, electrolytes, glucose and arterial blood gases were determined. RESULTS: Ultrafilterable circulating magnesium concentrations were determined in 74 of 84 neonatal ICU patients. On admission to the neonatal ICU, 23 (31.1%) of 74 neonates had ultrafilterable hypomagnesemia; two (2.7%) of 74 patients had ultrafilterable hypermagnesemia. Neonatal ICU patients had significantly lower (p < .001) ultrafilterable magnesium concentrations compared with normal neonates. Hypomagnesemic ICU patients required mechanical ventilatory support more frequently than did normomagnesemic ICU neonates (p < .05). Ionized hypocalcemia was a common finding in our patients (34 [42%] of 81). However, ultrafilterable hypomagnesemia was not statistically associated with ionized hypocalcemia (p > .05). Despite the below normal serum concentrations of ultrafilterable magnesium observed in our study, there was no impairment in parathyroid hormone secretion. CONCLUSIONS: Ultrafilterable hypomagnesemia is a common finding in neonates admitted to the ICU. Ultrafilterable hypomagnesemia is associated with the need for mechanical ventilation. To our knowledge, this is the first report of ultrafilterable magnesium concentrations in normal and sick neonates.

Prevention of thromboembolism in spinal cord injury: role of low molecular weight heparin.

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are major causes of morbidity and mortality in patients with acute spinal cord injury. Our preliminary studies indicated that low molecular weight heparin (LMWH) was significantly more effective than standard heparin in preventing these complications. We have now extended these studies by screening an additional 122 patients and treating 60 who met predefined criteria with LMWH in a dose of 3,500 anti-Xa U given subcutaneously once daily for 8 weeks. All patients were examined daily at bedside and had regularly scheduled venous ultrasonography; those with abnormalities had confirmatory venography and lung scans. Postmortem examinations were conducted in those who died. Forty completed the trial without incident, 6 had DVT (4 proximal and 2 distal), 1 had a fatal PE, 1 had postoperative bleeding requiring discontinuation of the LMWH, 10 were transferred or discharged, and 2 died of respiratory failure. The percentage of patients free of thrombosis or bleeding after 8 weeks of treatment was 85.9 +/- 5.0% standard error of mean (SEM). Thirty-three patients entered a follow-up observation period of 4 weeks without thromboprophylaxis; 2 weeks into this period 1 had a proximal DVT and 1 had a fatal PE; the course of the remainder was uneventful. We conclude that LMWH compares favorably with standard heparin in preventing venous thromboembolism, and is associated with significantly less bleeding. Eight weeks of prophylaxis seems adequate for most patients.

Single-dose intravenous therapy with pamidronate for the treatment of hypercalcemia of malignancy: comparison of 30-, 60-, and 90-mg dosages.

PURPOSE: To determine the efficacy, dose-response relationship, and safety of 30, 60, and 90 mg of a single intravenous dose of an aminobisphosphonate, pamidronate (APD), for the treatment of moderate to severe hypercalcemia of malignancy. PATIENTS AND METHODS: Patients with histologically proven cancer and a corrected serum calcium level of at least 12.0 mg/dL after 48 hours of normal saline hydration were enrolled in a double-blind, multicenter, randomized clinical trial. Pamidronate in 30-, 60-, or 90-mg doses was administered as a single 24-hour infusion. Serum calcium corrected for albumin, urine hydroxyproline, and calcium excretion, and serum parathyroid hormone (PTH) (1-84) were determined before and after pamidronate therapy. RESULTS: Thirty-two men and 18 women entered the study. A dose-response relationship for normalization of corrected serum calcium was seen after pamidronate administration. Corrected serum calcium normalized in 40% of patients who received 30 mg, in 61% of patients who received 60 mg, and in 100% of patients who received 90 mg of pamidronate. The decline in the serum calcium level was associated with decreased osteoclastic skeletal resorption evidenced by a decrease in urine calcium and hydroxyproline excretion. Among those with a normalized corrected serum calcium level, the mean (median) duration of normalization of the corrected serum calcium value was 9.2 (4), 13.3 (5), and 10.8 (6) days in the 30-, 60-, and 90-mg treatment groups, respectively. The response of hypercalcemia to pamidronate was not significantly influenced by the presence of skeletal metastases. PTH 1-84, suppressed in patients on entry into this study, increased to a greater extent in those patients with osteolytic skeletal metastases compared with those with humoral hypercalcemia of malignancy. Clinical improvement, including improved mental status and decreased anorexia, accompanied the decline in the corrected serum calcium level in all three treatment groups. Side effects included low-grade fever, asymptomatic hypocalcemia, hypomagnesemia, and hypophosphatemia. CONCLUSIONS: A single-dose infusion of 60 to 90 mg of pamidronate was highly effective and well tolerated and normalized corrected serum calcium in nearly all patients (61% to 100%) with hypercalcemia of malignancy.

Dose-response study of alendronate sodium for the treatment of cancer-associated hypercalcemia.

PURPOSE: A randomized, double-blind, dose-ranging study of single-dose intravenous (IV) therapy with alendronate sodium (aminohydroxybutylidene bisphosphonate) was performed in patients with cancer-associated hypercalcemia. PATIENTS AND METHODS: Patients with hypercalcemia who had not received antitumor therapy in the preceding 7 days were treated with 48 hours of IV hydration. Patients with persistent hypercalcemia (albumin-corrected serum calcium concentration [CSCC] > or = 11.5 mg/dL) were randomly assigned to receive 2.5, 5, 10, or 15 mg of alendronate infused over 2 hours, or 10 mg of alendronate infused over 24 hours. Fifty-nine patients were treated and 50 patients were assessable for the dose-response relationship. RESULTS: Normalization of CSCC (< or = 10.5 mg/dL) was achieved in 22%, 82%, 75%, and 90% of assessable patients in the 2.5-, 5-, 10- (2- and 24-hour groups pooled), and 15-mg dose groups, respectively, within 8 days of therapy. Doses > or = 5 mg were significantly superior to the 2.5-mg dose level (P < .05). There was no significant difference in the minimum CSCC achieved between the 2- and 24-hour infusions of the 10-mg dose. Based on an intent-to-treat analysis of all randomized patients, the overall complete response rate was 74% for dose levels greater than 2.5 mg. For assessable patients who responded to > or = 5 mg of alendronate, the estimated median duration of normocalcemia was 10 days (range, 1 to 25). The estimated median time to relapse (CSCC > 11.5 mg/dL) was 15 days from initial treatment and 12 days from initial response, respectively. Adverse events included a transient febrile response in 34% of patients and eight episodes of reversible elevations in serum transaminase levels among treated patients. CONCLUSION: While a statistically significant dose-response relationship was not clearly evident at doses greater than 5 mg, single doses of > or = 5 mg alendronate sodium effectively lowered serum calcium concentrations and were well tolerated in the treatment of cancer-associated hypercalcemia.

Pathophysiology and management of severe hypercalcemia.

The principal pathophysiologic alteration in severe hypercalcemia accompanying hyperparathyroidism and malignancy is enhanced osteoclastic bone resorption. Hypercalcemia impairs renal mechanisms that lead to sodium and calcium excretion; PTH and PTHrP acting on renal tubules enhance further calcium reabsorption. Although rehydration is often necessary as an initial therapy of hypercalcemia, the cornerstone of therapy is to inhibit osteoclastic bone resorption. The bisphosphonates, plicamycin, gallium, and calcitonin all inhibit osteoclastic bone resorption. Calcitonin is the most rapidly acting agent. Toxicities of calcitonin are minimal, yet its therapeutic efficacy is limited by lack of potency and tachyphylaxis. The second-generation bisphosphonates such as pamidronate represent a class of compounds that are extremely effective in inhibiting the metabolic function of the osteoclast. Given in a single infusion, a significant majority of patients will have normalization of corrected serum calcium lasting, on average, 1-2 weeks. Therapeutic benefit will be of greater duration because most patients remain only minimally symptomatic until corrected serum calcium rises above 11.5 mg/dL. Side effects of low-grade fever, hypophosphatemia, hypomagnesemia, and hypocalcemia may occur. Gallium nitrate is a potent inhibitor of bone resorption and may be of increased clinical value when more efficient administration protocols can be developed. Plicamycin, available for two decades, has cumulative toxicities and is less potent than the aminobisphosphonates. Renal insufficiency often accompanies severe hypercalcemia. The nephrotoxicity of gallium nitrate and plicamycin should preclude their use when there is moderate impairment of renal function, and amino bisphosphonates become the treatment of choice in these patients. Although several authors have advocated individualized approaches to the management of hypercalcemia, the potency and duration of action of the aminobisphosphonates make them a reasonable treatment choice for most patients with symptomatic hypercalcemia. Most importantly, the most effective therapy for hypercalcemia is to recognize and treat the underlying disease. Acute primary hyperparathyroidism requires surgery. The effective treatment of hypercalcemia of malignancy allows the introduction of tumor-specific therapy, limits morbidity, and shortens and deintensifies hospitalization. At times, the most appropriate and compassionate decision (particularly in patients with malignancy who have exhausted all therapeutic options and have relentless bone pain) is to withhold therapy for hypercalcemia. Future therapies directed at the osteoclast, such as more potent later-generation bisphosphonates; inhibitors of osteoclast attachments and inhibitors of peptides, which stimulate osteoclastic bone resorption, may permit safe, easily administered, outpatient therapies that will improve the quality of life for hypercalcemic patients.

Analysis of parathyroid hormone's principal receptor-binding region by site-directed mutagenesis and analog design.

Previous deletion studies established that the 25-34 region of PTH is important for receptor binding. We used oligonucleotide-directed mutagenesis to generate 47 different mutations in this region of human (h) PTH-(1-84) and evaluated cAMP-stimulating activity in ROS 17/2.8 cells. The hydrophobic residues Leu24 and Leu28 stood out as mutationally intolerant sites, while neighboring polar residues were comparatively tolerant. A series of synthetic PTH analogs was designed to test these residues further. The affinity of [Tyr34]hPTH-(1-34)NH2 for ROS 17/2.8 cells [dissociation constant (Kd), approximately 5 nM)] was dramatically reduced by the substitution of either Leu24 or Leu28 with Glu (Kd, approximately 20,000 and 8,000 nM, respectively). The Val31-->Glu substitution also sharply reduced affinity (Kd, approximately 200 nM). In contrast, the nearby charge-reversing change of Asp30-->Lys had no effect on binding affinity (Kd, approximately 5 nM). Similar effects were observed in the opposum kidney cell line. The binding of [Tyr34]hPTH-(15-34)NH2 to ROS 17/2.8 and opposum kidney cells (Kd, approximately 10 microM) was abolished by Glu substitutions at position 24, 28, or 31; the Lys30 change was without effect. These results suggest that the adverse effects of the Glu substitutions on receptor binding are not due purely to the disruption of tertiary interactions with the 1-14 region. Circular dichroism spectroscopy indicated that the substitutions do not affect local helical structure. The data suggest that Leu24, Leu28, and Val31 contribute important receptor-binding interactions and are consistent with the hypothesis that an amphipathic alpha-helix in the carboxy-terminal region of PTH-(1-34) is involved in receptor binding.