Immunoassay-Based Drug Tests Are Inadequately Sensitive for Medication Compliance Monitoring in Patients Treated for Chronic Pain

BACKGROUND

Enzyme immunoassays (EIA) have notable limitations for monitoring therapeutic compliance in pain management. Chromatography coupled with mass spectrometry provides definitive results and superior sensitivity and specificity over traditional EIA testing.

OBJECTIVE

To analyze and compare the sensitivity of EIA results together with known prescriptions to liquid chromatography-tandem mass spectrometry (LC-MS/MS) for monitoring drug use (and abuse) in patients treated for chronic pain.

STUDY DESIGN

A total of 530 urine samples from patients being treated for chronic pain were studied.

SETTING

Pain management clinic in the United States.

METHODS

The samples were tested for a profile of chronic pain medications and illicit drugs with commercially available EIA kits followed by analysis with Agilent LC-MS/MS system.

RESULTS

The EIAs exhibited poor sensitivity and high rates of false negative results in the pain management setting. For example, 21% of EIA for opiates show false negative results. Mass spectrometry methods were more sensitive, detected a broader range of drugs and metabolites, and could detect non-prescribed drug use and simulations in compliance.

LIMITATIONS

Patients do not always accurately report drug use information, and some drugs do not have EIA methods available for comparative purposes.

CONCLUSIONS

Mass spectrometry is a more robust and reliable method for detection of drugs used in the pain management setting. Due to the extent of undisclosed use and abuse of medications and illicit drugs, LC-MS/MS testing is necessary for adequate and accurate drug detection. In addition, LC-MS/MS methods are superior in terms of sensitivity and number of compounds that can be screened, making this a better method for use in pain management. Key words: Pain management, enzyme immunoassays, mass spectrometry, urine drug testing, prescription status, compliance.

KIMS, CEDIA, and HS-CEDIA immunoassays are inadequately sensitive for detection of benzodiazepines in urine from patients treated for chronic pain

BACKGROUND

Patients treated for chronic pain may frequently undergo urine drug testing to monitor medication compliance and detect undisclosed prescribed or illicit drug use. Due to the increasing use and abuse of benzodiazepines, this class of medications is often included in drug screening panels. However, immunoassay-based methods lack the requisite sensitivity for detecting benzodiazepine use in this population primarily due to their poor cross-reactivity with several major urinary benzodiazepine metabolites. A High Sensitivity Cloned Enzyme Donor Immunoassay (HS-CEDIA), in which beta-glucuronidase is added to the reagent, has been shown to perform better than traditional assays, but its performance in patients treated for chronic pain is not well characterized.

OBJECTIVES

To determine the diagnostic accuracy of HS-CEDIA, as compared to the Cloned Enzyme Donor Immunoassay (CEDIA) and Kinetic Interaction of Microparticles in Solution (KIMS) screening immunoassays and liquid chromatography-tandem mass spectrometry (LC-MS/MS), for monitoring benzodiazepine use in patients treated for chronic pain.

STUDY DESIGN

A study of the diagnostic accuracy of urine benzodiazepine immunoassays.

SETTING

The study was conducted at an academic tertiary care hospital with a clinical laboratory that performs urine drug testing for monitoring medication compliance in pain management.

METHODS

A total of 299 urine specimens from patients treated for chronic pain were screened for the presence of benzodiazepines using the HS-CEDIA, CEDIA, and KIMS assays. The sensitivity and specificity of the screening assays were determined using the LC-MS/MS results as the reference method.

RESULTS

Of the 299 urine specimens tested, 141 (47%) confirmed positive for one or more of the benzodiazepines/metabolites by LC-MS/MS. All 3 screens were 100% specific with no false-positive results. The CEDIA and KIMS sensitivities were 55% (78/141) and 47% (66/141), respectively. Despite the relatively higher sensitivity of the HS-CEDIA screening assay (78%; 110/141), primarily due to increased detection of lorazepam, it still missed 22% (31/141) of benzodiazepine-positive urines. The KIMS, CEDIA, and HS-CEDIA assays yielded accuracies of 75%, 79%, and 90%, respectively, in comparison with LC-MS/MS.

LIMITATIONS

This study was limited by its single-site location and the modest size of the urine samples utilized.

CONCLUSIONS

While the HS-CEDIA provides higher sensitivity than the KIMS and CEDIA assays, it still missed an unacceptably high percentage of benzodiazepine-positive samples from patients treated for chronic pain. LC-MS/MS quantification with enzymatic sample pretreatment offers superior sensitivity and specificity for monitoring benzodiazepines in patients treated for chronic pain.

Patient Misidentifications Caused by Errors in Standard Bar Code Technology

BACKGROUND

Bar code technology has decreased transcription errors in many healthcare applications. However, we have found that linear bar code identification methods are not failsafe. In this study, we sought to identify the sources of bar code decoding errors that generated incorrect patient identifiers when bar codes were scanned for point-of-care glucose testing and to develop solutions to prevent their occurrence.

METHODS

We identified misread wristband bar codes, removed them from service, and rescanned them by using 5 different scanner models. Bar codes were reprinted in pristine condition for use as controls. We determined error rates for each bar code–scanner pair and manually calculated internal bar code data integrity checks.

RESULTS

As many as 3 incorrect patient identifiers were generated from a single bar code. Minor bar code imperfections, failure to control for bar code scanner resolution requirements, and less than optimal printed bar code orientation were confirmed as sources of these errors. Of the scanner models tested, the Roche ACCU-CHEK® glucometer had the highest error rate. The internal data integrity check system did not detect these errors.

CONCLUSIONS

Bar code–related patient misidentifications can occur. In the worst case, misidentified patient results could have been transmitted to the incorrect patient medical record. This report has profound implications not only for point-of-care testing but also for bar coded medication administration, transfusion recipient certification systems, and other areas where patient misidentifications can be life-threatening. Careful control of bar code scanning and printing equipment specifications will minimize this threat to patient safety. Ultimately, healthcare device manufacturers should adopt more robust and higher fidelity alternatives to linear bar code symbologies.

Rapid liquid chromatography/tandem mass spectrometer (LCMS) method for clozapine and its metabolite N-desmethyl clozapine (norclozapine) in human serum

Clozapine is indicated for the treatment of schizophrenia and related psychotic disorders. Several methods have been developed for monitoring Clozapine levels; however, they possess limited specificity and are often laborious. This study describes a simple liquid chromatography/tandem mass spectrometer (LCMS) method in human serum. The ion transitions monitored were m/z 327, 270, 296 for Clozapine, m/z 313, 192, 227 for Norclozapine and m/z 328, 271 for Loxapine. The assay is linear (25-1000 ng/ml) and showed a good correlation (r=0.98) within the analytical range of 79-1210 ng/ml in human serum. This assay is highly specific and sensitive for the simultaneous measurements of Clozapine and Norclozapine. The simplification of this assay makes it ideal for high throughput analyses of the patient samples in a routine clinical laboratory staffed with general medical technologists.

Quantification of busulfan in plasma using liquid chromatography electrospray tandem mass spectrometry (HPLC-ESI-MS/MS)

Busulfan is a chemotherapy drug widely used as part of conditioning regimens for patients undergoing bone marrow transplantation (BMT). Challenges of busulfan treatment include a narrow therapeutic window and wide inter- and intra-patient variability. Inappropriately low drug levels lead to relapse and even graft rejection, while higher doses frequently have toxic and sometimes fatal consequences. Maintenance of plasma busulfan concentrations using repeated measurements and proper adjustment of dosage can reduce busulfan-related toxicity and improve treatment outcomes. We describe a rapid (2-minute total analysis time per sample) and simple method for accurate and precise busulfan concentration determination in plasma samples (100 microL) using high performance liquid chromatography combined with electrospray positive ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Busulfan is isolated from plasma after internal standard (busulfan-D(8))-methanol extraction, dilution with mobile phase (ammonium acetate-formic acid-water), and centrifugation. The supernatant plasma is injected onto the HPLC-ESI-MS/MS and quantified using a six-point standard curve. The assay is linear from 0.025 microg/mL (approximately 0.1 micromol/L) to at least 6.2 microg/mL (approximately 25 micromol/L) with precisions of <5% over the entire range.

Hybrid carcinoma of the salivary gland: salivary duct adenocarcinoma adenoid cystic carcinoma

AIMS

Hybrid tumours of the salivary gland are rare neoplasms that have been described only in the parotid and palate. Their recognition is important particularly when the component tumours have different biological behaviours. The occurrence of a submandibular hybrid tumour has not been reported.

METHODS AND RESULTS

We describe a case of a 36-year-old woman with a hybrid carcinoma composed of salivary duct adenocarcinoma and adenoid cystic carcinoma of the right submandibular gland. There was no evidence of a pre-existing or concurrent pleomorphic adenoma. The presence of the two components was verified by differential immunohistochemical staining using a panel of cytokeratin, vimentin, smooth muscle actin and S100. The patient subsequently developed metastases to the pelvis, lumbar, vertebra and wrist. The clinical course in this patient was consistent with the behaviour of the salivary duct adenocarcinoma component.

CONCLUSIONS

The histogenesis of hybrid tumours is largely unknown, but in this case it may represent diverging differentiation of luminal tumour cells. Because some histological features of different salivary gland tumours overlap, immunohistochemistry is a valuable tool especially when used to delineate the components of a hybrid tumour.

Tumor growth and tumor radiosensitivity in mice given myeloprotective doses of fibroblast growth factors

BACKGROUND

Radiation at doses high enough to cure cancer also frequently destroys normal tissue. Development of agents that protect normal tissue without also protecting diseased tissue has been difficult. In vivo radioprotection of bone marrow by acidic and basic fibroblast growth factors (FGF1 and FGF2, respectively) has recently been demonstrated after whole-body irradiation of C3H/HeN mice.

PURPOSE

Our purpose was to determine whether myeloprotective doses of those growth factors also protect malignant tumors.

METHODS

First, we investigated the effects of exogenous FGF1 or FGF2 (FGF1/2) administration (treatment group receiving two intravenous injections of 3 micrograms FGF1/2 per mouse 24 hours and 4 hours before local irradiation of right hind leg and control group receiving two intravenous injections of 0.1 mL of saline) on growth and radiosensitivity of three transplantable murine tumors (one squamous cell carcinoma [SCC-VII] and two sarcomas [KHT and Rif-1]), all of which were grown in C3H/HeN mice. We then evaluated the effect of FGF1/2 on tumor cell proliferation, cell cycle distribution, and pulmonary metastatic frequency in the mice. Specifically, survival studies were performed in mice treated with 0, 6, 6.5, 7.5, 8.5, 9, or 10 Gy whole-body irradiation with or without FGF2 (n = 250). Rif-1 (n = 40), KHT (n = 40), and SCC-VII (n = 40) tumors were implanted in the hind leg of mice, and mice were treated with FGF2 or saline when their tumor-bearing thighs were 9 mm in diameter. In separate experiments (treatment group receiving two injections of 3 micrograms each of FGF2 [6 micrograms total] either intravenously or intratumorally 24 hours and 4 hours before local tumor irradiation and control group receiving 0.1 mL saline), tumor growth was followed, and mice were killed to count lung metastases and measure tumor proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine labeling at various times thereafter (three to eight mice per group). Tumor growth curves of untreated and irradiated tumors were determined with and without intravenous or intratumoral FGF1/2 in SCC-VII tumors (n = 120). Radiation doses to the tumor-bearing leg were 15 and 30 Gy for SCC-VII, 30 Gy for Rif-1, and 15 Gy for KHT. From each experiment, the mean (+/- 1 standard error) was calculated from data obtained from three to 20 mice. Statistical tests used included two-tailed Student's t test, the chi-squared test, and Fisher's exact test. All P values represent two-tailed tests of statistical significance.

RESULTS

There was no statistically significant difference in tumor growth rate between FGF2-treated and saline-treated mice when FGF2 was administered intravenously at doses and schedules found to be optimally myeloprotective in whole-body irradiation experiments. Intravenous administration of FGF2 did not induce lung metastases, and it did not augment the S-phase fraction of tumor cells. Likewise, there was no evidence of enhanced cell proliferation as measured by PCNA-labeling index. Intratumoral injection of FGF1/2 did increase the size of SCC-VII tumors (P < .05 [Student's t test] at 3 days after treatment); however, the radiation response after intratumoral injection of growth factor was not compromised.

CONCLUSION

Low intravenous doses of FGF1 or FGF2 appear to protect bone marrow from the toxic effects of radiation without increasing the rates of tumor growth or metastases or decreasing the radiosensitivity of tumors.

Ligand-induced conformational change of lipoprotein(a)

Lipoprotein(a) undergoes a dramatic, reversible conformational change on binding 6-amino-hexanoic acid (6-AHA), as measured by a decrease in the sedimentation rate, the magnitude of which is directly proportional to apo(a) mass. A similar reversible transition from a compact to an extended form has been shown to occur in plasminogen on occupation of a weak lysine binding site. The magnitude of the change in Lp(a) with large apo(a) is about 2.5 times that seen for plasminogen, however. Regardless of apo(a) size, binding analysis indicated that 1.4-4 molecules of 6-AHA bound per Lp(a) particle; the midpoint of the conformational change occurs at 6-AHA concentrations of 100-200 mM. Since rhesus Lp(a), which lacks both kringle V and the strong lysine binding site on kringle IV 10, also undergoes a similar conformational change, the phenomenon may be attributable to weak sites, possibly located in K-IV 5-8. Compact Lp(a), i.e., native Lp(a), had a frictional ratio (f/f0) of 1.2 that was independent of apo(a) mass, implying constant shape and hydration. For Lp(a) in saturating 6-AHA, f/f0 ranged from 1.5 to over 2.1 for the largest apo(a) with 32 K-IV, indicating a linear relationship between hydrodynamic volume and number of kringles, as expected for an extended conformation. However, only the variable portion of apo(a) represented by the K-IV 2 domains, participates in the conformational change; the invariant K-IV 3-9 domains remain close to the surface. These results suggest that apo(a) is maintained in a compact state through interactions between weak lysine binding sites and multiple lysines on apoB and/or apo(a), and that these interactions can be disrupted by 6-AHA, a lysine analog.

Basic fibroblast growth factor radioprotects bone marrow and not RIF1 tumor

We examined the potential of bFGF to function as a radioprotector of bone marrow (BM). Total intravenous doses of bFGF ranged from 1 to 24 micrograms/mouse, in 2 divided doses. Whole body radiation (WBI) was given in a single fraction to C3H mice. Histologic observations were performed on femur BM at various times after bFGF (or placebo) treatment. Thigh radiation in thigh-tumor bearing mice was delivered in a single fraction. bFGF increased the LD50/30 of mice in a dose dependent fashion, with an apparent maximum protection obtained with > or = 6 micrograms given half 24 h and half 4 h before irradiation. BM histology shows prominent recovery of megakaryocytes and all cell lineages along with less loss in cellularity compared to control irradiated animals. No radioprotection of RIF1 tumors after bFGF was detected. These results indicate that bFGF may be a selective radioprotector of normal tissue.

Subunit composition of lipoprotein(a) protein

We determined the molecular weight of four different apo(a) polymorphs by sedimentation equilibrium in 6 M guanidine hydrochloride in order to estimate the molar ratio of apo(a) to apoB in Lp(a). They had molecular weights of 289,000, 310,000, 341,000, and 488,000 and 15, 16, 18, and 27 kringle 4 domains, respectively. Their carbohydrate content was similar (23.2 wt %), as was their partial specific volume (0.682 mL/g). Knowing the mass of apo(a), we estimated the molar ratio of apo(a) to apoB from (1) the molecular weight of the protein moiety of the four respective parent Lp(a) particles as calculated from their mass and percentage composition and the mass of apoB, (2) the mass of apo(a) lost from Lp(a) upon its reduction and carboxymethylation, by determining the difference in mass between Lp(a) and Lp(a-), and (3) from the mass (measured by sedimentation equilibrium in 6 M guanidine hydrochloride) of the lipid-free apoB-apo(a) complex (1.06 x 10(6) daltons) of the Lp(a) particle with the smallest apo(a) polymorph by subtracting the mass of apoB. Our results obtained with each of the three different physicochemical methods indicated that the protein moiety of each of the four Lp(a) particles that was investigated consisted of a complex of two molecules of apo(a) and one molecule of apoB.

Binding and degradation of lipoprotein(a) and LDL by primary cultures of human hepatocytes. Comparison with cultured human monocyte-macrophages and fibroblasts

Although lipoprotein(a) (Lp[a]) has structural similarities to low-density lipoprotein (LDL) that include the presence of apolipoprotein B100, there is some disagreement over the strength of its interaction with the LDL receptor and its cellular catabolism by the LDL receptor-mediated pathway. To clarify this subject we evaluated LDL receptor-mediated binding and degradation of Lp(a) and LDL in three human cell lines. The binding of 50 nmol/L Lp(a) at 37 degrees C to the LDL receptor of primary hepatocytes, macrophages, and fibroblasts was only 10%, 29%, and 29% of the respective value obtained with 50 nmol/L LDL. Analysis of 4 degrees C binding curves indicated that Lp(a) and LDL had equal affinities for the LDL receptor of fibroblasts, whereas maximal binding of Lp(a) was remarkably lower than that of LDL. LDL receptor-mediated degradation of 50 nmol/L Lp(a) in hepatocytes, macrophages, and fibroblasts was only 17%, 22%, and 26%, respectively, of the value obtained with 50 nmol/L LDL and varied greatly among the cells in that it was lowest in hepatocytes, an order of magnitude greater in macrophages, and two orders of magnitude greater in fibroblasts. In contrast, the nonspecific degradation rate of Lp(a) was similar to that of LDL in each of the three tested cell lines. However, the proportion of the degradation of Lp(a) that was nonspecific varied greatly, being 76%, 58%, and 33% in hepatocytes, macrophages, and fibroblasts, respectively. These studies indicate that not only is Lp(a) recognized by the LDL receptor but also that, in fibroblasts, Lp(a) and LDL have equal affinities for the LDL receptor, although Lp(a) has a much lower receptor occupancy than LDL. Additionally, they show that there are great cellular differences in the LDL receptor-mediated degradation of Lp(a). If these results can be extrapolated in vivo, where normal LDL levels are 40- to 50-fold higher than those of Lp(a), it would be unlikely that the hepatic LDL receptor is significantly involved in the degradation of Lp(a).

Methods of suicide used by Irish and Japanese samples: a cross-cultural study from 1964 to 1979

In this study were compared 8 methods of suicide by sex in three different nations over a 16-yr. period. Frequencies by sex showed statistically significant preference for method of suicide. Trend analyses by method of suicide by sex and nation indicated 19 were statistically significant.

Polymorphic forms of Lp(a) with different structural and functional properties: cold-induced self-association and binding to fibrin and lysine-Sepharose

Two different Lp(a) polymorphs were isolated from the same individual and shown to have important differences both in their solution properties and in interaction with lysine Sepharose and fibrin. One Lp(a) particle (d-Lp(a)) with a large apo(a) isoform had a density of 1.087 g/ml and a molecular weight of 3.17 million, while the other Lp(a) particle with a small apo(a) isoform having a mobility faster than that of apoB was larger and had a molecular weight of 3.75 million and a density of 1.054 g/ml. D-Lp(a) underwent cold-induced self-association and also had a higher affinity for lysine Sepharose, whereas the other Lp(a) polymorph did not. Both Lp(a) particles bound fibrin via two different binding sites, one of which involved fibrin lysine residues which are also recognized by plasminogen. Lysine-mediated binding of d-Lp(a) by fibrin was ten times stronger than that of the other Lp(a) particle, whereas non-lysine-mediated binding of either Lp(a) species by fibrin was of equal strength. At saturation, 80% of d-Lp(a) bound fibrin at sites that did not involve lysine residues, whereas only 33% of the other Lp(a) polymorph bound to these sites. These findings indicate that the binding of Lp(a) to fibrin is more complex than previously thought and imposes another layer of difficulty on our understanding of how Lp(a) regulates and/or impairs fibrinolysis.

Management of pediatric postoperative chylothorax

Questions persist about the management of postoperative chylothorax in infants and children. Our experience with postoperative chylothorax over the most recent decade (1980 to 1990) has been reviewed. The type and amount of drainage, data from cardiac catheterization and echocardiography, operative decisions and details, and eventual outcomes have been cataloged. All patients were initially treated with total gut rest, with operation reserved for unabated drainage. Chylothorax developed postoperatively in 15 infants and 11 children (18 with a cardiac procedure and 8 with a noncardiac procedure). The average age was 3.1 years. Spontaneous cessation and cure occurred in 19 (73.1%) of these 26 patients, with an average drainage duration of 11.9 days (range, 4 to 30 days). Those for whom operation was chosen drained preoperatively for an average of 29.2 days (range, 25 to 40 days). There were no deaths in either group. Complications were lymphopenia (2 patients) and fungal sepsis (1 patient). The amount of drainage per day was not significantly different between patients treated operatively and those treated nonoperatively. Failure of nonoperative management was associated with venous hypertension from increased right-sided cardiac pressures or central venous thrombosis (p < 0.05, Fisher's exact test). Presumably this increased pressure is transmitted to the lymphatic system. These patients should be identified early and considered for thoracic duct suture or pleuroperitoneal shunting.

Capital punishment in Texas: comparison of some factors shared by 50 convicted murderers and their victims

The mean age of 50 convicted murderers at time of execution was compared to the mean age of their victims at time of death. The mean ages compared were not significantly different.

Clinical trial of the Braden Scale on an acute care medical unit

Pressure ulcers in hospitalized patients represent a significant challenge to the health professionals who care for these patients. This challenge extends to the health care system as a whole because of the staggering costs associated with pressure ulcer resolution. Although the relative benefits of various treatment methods have long been debated, intervention before ulcer formation clearly stands as the most efficacious approach to this problem. The Braden Scale for Predicting Pressure Sore Risk, a recently developed paper tool, was evaluated in our acute care medical unit for its ability to predict pressure ulcer occurrence. The sensitivity of the Braden Scale in this evaluation was much lower than that reported in other published studies. The Braden Scale was less effective than the nurse judgment prediction method, the current prevailing prediction method at this institution. The gravity of these results, however, is unclear because of the questionable incidence of ulcers in this study, which may be artificially high due to permissive criteria used in the identification of stage 1 ulcers. We determined that the lack of unequivocally defined criteria for the identification of stage 1 ulcers may contribute to variance between studies. We also found that intervention measures were used only 27% of the time after the identification of patients at risk.

Mechanisms by which lipoprotein lipase alters cellular metabolism of lipoprotein(a), low density lipoprotein, and nascent lipoproteins. Roles for low density lipoprotein receptors and heparan sulfate proteoglycans

We sought to investigate effects of lipoprotein lipase (LpL) on cellular catabolism of lipoproteins rich in apolipoprotein B-100. LpL increased cellular degradation of lipoprotein(a) (Lp(a)) and low density lipoprotein (LDL) by 277% +/- 3.8% and 32.5% +/- 4.1%, respectively, and cell association by 509% +/- 8.7% and 83.9% +/- 4.0%. The enhanced degradation was entirely lysosomal. Enhanced degradation of Lp(a) had at least two components, one LDL receptor-dependent and unaffected by heparitinase digestion of the cells, and the other LDL receptor-independent and heparitinase-sensitive. The effect of LpL on LDL degradation was entirely LDL receptor-independent, heparitinase-sensitive, and essentially absent from mutant Chinese hamster ovary cells that lack cell surface heparan sulfate proteoglycans. Enhanced cell association of Lp(a) and LDL was largely LDL receptor-independent and heparitinase-sensitive. The ability of LpL to reduce net secretion of apolipoprotein B-100 by HepG2 cells by enhancing cellular reuptake of nascent lipoproteins was also LDL receptor-independent and heparitinase-sensitive. None of these effects on Lp(a), LDL, or nascent lipoproteins required LpL enzymatic activity. We conclude that LpL promotes binding of apolipoprotein B-100-rich lipoproteins to cell surface heparan sulfate proteoglycans. LpL also enhanced the otherwise weak binding of Lp(a) to LDL receptors. The heparan sulfate proteoglycan pathway represents a novel catabolic mechanism that may allow substantial cellular and interstitial accumulation of cholesteryl ester-rich lipoproteins, independent of feedback inhibition by cellular sterol content.

Unemployment and suicide in Northern Ireland

For Northern Ireland, yearly mean percentages of unemployment and suicide rates (per 100,000 population) for specific age groups and by sex were compared over a 19-year period. Significant results were obtained for only two age groups of males (15-24 yr. and 45-54 yr.) and none for females.

Comparative binding and degradation of lipoprotein(a) and low density lipoprotein by human monocyte-derived macrophages

The binding and degradation of equimolar concentrations of lipoprotein(a) (Lp(a)) and low density lipoprotein (LDL) isolated from the same individual were studied in primary cultures of human monocyte-derived macrophages (HMDM). At 4 degrees C, LDL receptor-mediated binding of both Lp(a) and LDL was of low affinity, being 0.8 and 0.23 microM, respectively. Competitive binding studies indicated that the binding of Lp(a) to HMDM was competed 63% by excess LDL. In contrast to the 4 degrees C binding data, the degradation of Lp(a) at 37 degrees C was mainly nonspecific because the amount of Lp(a) processed by the LDL receptor pathway in 5 h was 17% that of LDL. According to pulse-chase experiments, this phenomenon may be accounted for by the facts that less Lp(a) is bound to HMDM at 37 degrees C and that Lp(a) has a lower intrinsic degradation rate and was not due to increased intracellular accumulation or retroendocytosis of the lipoprotein. Degradation of both lipoproteins was primarily lysosomal and only modestly affected by up- or down-regulation of the LDL receptor. The rate of retroendocytosis in HMDM was approximately equal to the degradation rate and appeared to be independent of the type of lipoprotein used, up- or down-regulation of the LDL receptor, or the presence of the lysosomotropic agent chloroquine. Overall, the results indicate that HMDM degrade Lp(a) mainly via a nonspecific pathway with only 25% of total Lp(a) degradation occurring through the LDL receptor pathway. As both 37 degrees C degradation and 4 degrees C binding of LDL are mainly LDL receptor specific, the different metabolic behavior observed at 37 degrees C suggests that Lp(a) undergoes temperature-induced conformational changes on cooling to 4 degrees C that allows better recognition of Lp(a) by the LDL receptor at a temperature lower than the physiological temperature of 37 degrees C. How apo(a) affects these structural changes remains to be established.

Obtaining reliable plasma sodium and glucose determinations from pulmonary artery catheters

In critically ill patients, blood specimens are frequently withdrawn from intravascular catheters without consideration of possible infusate contamination, of test accuracy, or of undue blood loss. The reliability of sodium (Na+) and glucose determinations withdrawn from the venous infusion port of a pulmonary artery catheter was studied in 30 patients after cardiac surgery. Catheter patency was maintained by a saline and heparin infusate. Venipuncture samples for Na+ and glucose served as controls. A sample containing the dwell volume of the catheter and the stopcock (1 ml) was withdrawn and discarded, followed by fifteen 1 ml samples being taken for analysis. It was concluded that Na+ values are stable after discard of the catheter dwell volume and an additional milliliter of blood. Minimal clinical differences were found in the glucose values after discard of the catheter dwell volume and two additional milliliters of blood.

Enzyme-linked immunoassay for Lp[a]

Based on our findings that rabbit antisera raised against human Lp[a] or apo[a] have the potential to cross-react with plasminogen, and in some cases have nearly equal affinities for plasminogen and Lp[a], we have developed an assay for plasma Lp[a] based on a "sandwich" ELISA that is insensitive to the presence of plasminogen. This was accomplished through the use of anti-apo[a] as a capture antibody and quantitation of the bound Lp[a], i.e., the apoB-100-apo[a] complex, with an anti-apoB antibody. Although apo[a] is heterogeneous in size, all Lp[a] particles tested, either in pure form or contained in whole plasma, gave parallel dose-response curves and were immunologically equivalent. However, when purified Lp[a] particles with different apo[a] isoforms were studied, those having larger isoforms were, on a weight basis, less reactive than those having a smaller size. Nearly equivalent reactivity was observed when protein concentration was expressed on a molar basis. The distribution of Lp[a] in a population of 84 subjects was skewed with one-third of the individuals having less than 1 mg/dl Lp[a] protein. All subjects tested had measurable concentrations of Lp[a] with a lower limit of detection of 0.030 mg/dl Lp[a] protein. The mean level was 3.2 mg/dl with a range of 0.045 to 13.3 mg/dl. These studies demonstrate the successful development of an ELISA for Lp[a] protein that is insensitive to the presence of plasminogen; that heterogeneity of Lp[a] and apo[a] are an important source of variation in the assay; and the need for an appropriate Lp[a] standard in order to minimize this variation.

The menstrual cycle and punitiveness

Subjects (n = 59) read vignettes of seven different college disciplinary cases and for each one selected a level of punishment. Three groups of subjects consisted of women in the menstrual (n = 12), premenstrual (n = 10), and intermenstrual (n = 13) phases. In addition, there were conditions in which women who were approaching the premenstrual phase were led to believe they were in it (n = 7) or were still several days away from it (n = 7). Finally, there was sixth group: males of comparable age and background (n = 10). The six groups were responsive-and about equally so-to differences among the seven cases. However, the groups did not differ in average level of punishment selected nor did they differ in reliability of judgment across individuals. There was some indication that males and the women led to believe they were premenstrual, found the task to be harder than did the other groups.

The menstrual cycle and punitiveness

Subjects (n = 59) read vignettes of seven different college disciplinary cases and for each one selected a level of punishment. Three groups of subjects consisted of women in the menstrual (n = 12), premenstrual (n = 10), and intermenstrual (n = 13) phases. In addition, there were conditions in which women who were approaching the premenstrual phase were led to believe they were in it (n = 7) or were still several days away from it (n = 7). Finally, there was sixth group: males of comparable age and background (n = 10). The six groups were responsive-and about equally so-to differences among the seven cases. However, the groups did not differ in average level of punishment selected nor did they differ in reliability of judgment across individuals. There was some indication that males and the women led to believe they were premenstrual, found the task to be harder than did the other groups.

End-point dilution-fluorescent antibody technique for cloning hog cholera virus

Hog cholera virus was cloned by incubating selected pretitrated dilutions of the virus on PK-15 cell cultures for 2 hours. After a thorough washing, the coverslip cell cultures were overlaid with medium containing 0.1% hog cholera immune serum to prevent secondary foci. Forty-eight hours later, the cultures were vigorously washed and maintenance medium containing 5% bovine fetal serum was added. When examined by the fluorescent antibody technique 18 hours later, single plaques were observed in some cultures with no evidence of secondary foci. The virus clone subsequently yielded a homogeneous population of hog cholera virus that retained the characteristics of the parent strain; pathogenicity of the virus clone in pigs was demonstrated, and specific immunofluorescence occurred in infected cell cultures stained with fluorescein isothiocyanate-labeled antibody. The method used gave reasonable assurance of the cloned virus' freedom from extraneous agents.

Field evaluation of enzyme-linked immunosorbent assay for detection of antibody to African swine fever virus

The enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to African swine fever virus was evaluated under field conditions in the Dominican Republic. A total of 3,402 swine serums were tested by ELISA. All ELISA-positive serums (n = 224) and 426 of 2,760 ELISA-negative serums were retested by indirect immunofluorescence (IIF). There were no antibodies to ASF virus detected by IIF in ELISA-negative serums. By IIF, antibodies were detected in only a small portion of the ELISA-positive serums. The specificity and sensitivity of ELISA and IIF were investigated and discussed. It appears that poor quality serums had an effect in ELISA results. Detection of immunoglobulin (Ig) G and IgM classes of antibodies in the ELISA and IIF-positive serums were also performed and related to longevity of African swine fever virus infection. The ELISA is recommended as an efficient method in testing large number of serums; positive results are to be retested by IIF.

Persistent hog cholera infection detected during virulence typing of 135 field isolates

During the hog cholera (HC) eradication program in the United States, 135 field isolates were characterized by inoculation into specific-pathogen-free pigs. This gave origin to the classification of 61 (45%) as high virulent, 37 (27%) as low virulent, 29 (22%) as avirulent or immunizing, and 8 (6%) as capable of causing persistent infection. The persistent infections caused by the eight isolates were of long durtion, lasting in one instance to 152 days. The persistently infected pigs remained relatively free of clinical signs of HC but had high concentrations of HC virus (HCV) in their blood. When 6 of these pigs were given a second inoculation (with the virulent Ames strain of HCV), 2 died while the health status of 4 remained unchanged.

Bovine viral diarrhea infection in pregnant swine

Twenty pregnant gilts (5 groups of 4) were infected experimentally with 1 of 4 strains of bovine viral diarrhea virus (BVDV) administered intranasally-orally. Blood specimens were taken from the gilts on postinfection day (PID) 7 and cultured for virus. Serum specimens, obtained on PID 21 and at termination of the experiment, were tested for neutralizing antibodies. At 90 to 112 days of gestation, the gilts were euthanatized and their fetuses were examined for evidence of intrauterine infection. Evidence of infection was demonstrated in all of the gilts, either by isolation of BVDV at PID 7 or subsequently by detection of neutralizing antibody titers. Intrauterine infection was confirmed in one of 20 gilts by isolation of BVDV, detection of neutralizing antibodies, and demonstration of microscopic lesions in the fetuses. The microscopic lesions were characterized as nonsuppurative meningitis and choroiditis. Clinical signs of disease were not seen in the infected fetuses. Of 8 gilts exposed to strains of BVDV pathogenic for cattle, 1 gilt developed intrauterine infection, 2 gilts were found barren, and 3 gilts had significantly fewer fetuses than copora lutea.

The wakeful "type A" student

Eight type A students and eight that were type B slept in the laboratory for three consecutive nights. Type A showed more fragmented sleep, i.e., more spontaneous awakenings from sleep. No differences in REM pressure between As and Bs could be demonstrated, contradicting the hypothesis that both the personality traits of type A individuals and their coronary-proneness might be explained by chronic REM deprivation of type A individuals.

Avoidance of the handicapped: an attributional ambiguity analysis

We demonstrated a general strategy for detecting motives that people wish to conceal. The strategy consists of having people choose between two alternatives, one of which happens to satisfy the motive. By counterbalancing which one does so, it is possible to distill the motive by examining the pattern of choices that people make. The motive used in the demonstration is the desire we believe most people have to avoid the physically handicapped. Because they do not wish to reveal this desire, we predicted that they would be more likely to act on it if they could appear to choose on some other basis. In two studies we found that people avoided the handicapped more often if the decision to do so was also a decision between two movies and avoidance of the handicapped could masquerade as a movie preference.

Thermal inactivation of hog cholera virus in ham

Experiments were conducted to determine the temperatures required to inactivate hog cholera virus (HCV) in fresh ham after 1 minute and in cured and processed (canned) ham after 90 minutes. A momentary or "flash" temperature of 71 C for 1 minute caused inactivation of the virus in 15 of 15 cubes (2 cm3) of ham. Hog cholera virus was destroyed in 21 of 21 canned hams (weighing 0.91 kg each) when an internal temperature of 65 C was sustained for 90 minutes. Pigs were found to be more sensitive than tissue culture cells for detecting viable HCV in heat-processed fresh hams. Virus was isolated by tissue culture technique only from those hams exposed to temperatures below 61 C. The relative concentration of HCV in unheated cured hams of experimentally infected pigs varied over a wide range; these pigs were inoculated with the virulent Ames strain and were killed on postinfection day 6 or 7.

Avoidance of the handicapped: An attributional ambiguity analysis

We demonstrated a general strategy for detecting motives that people wish to conceal. The strategy consists of having people choose between two alternatives, one of which happens to satisfy the motive. By counterbalancing which one does so, it is possible to distill the motive by examining the pattern of choices that people make. The motive used in the demonstration is the desire we believe most people have to avoid the physically handicapped. Because they do not wish to reveal this desire, we predicted that they would be more likely to act on it if they could appear to choose on some other basis. In two studies we found that people avoided the handicapped more often if the decision to do so was also a decision between two movies and avoidance of the handicapped could masquerade as a movie preference.

Isolation of a new porcine enterovirus in the United States

A cytopathogenic virus isolated from an Iowa farm pig with diarrhea was identified as a member of Group 5 of the porcine enteroviruses. Clinical signs observed in other pigs in the herd were diarrhea, debilitation and gauntness. Morbidity and mortality rates were approximately 50% and 3% respectively.A Group 5 porcine enterovirus had not been previously isolated in North America according to the Western Hemisphere Committee on Animal Virus Characterization.

Tween 80: a marker for differentiation of hog cholera and bovine viral diarrhea viruses

Markers for differentiating hog cholera and bovine viral diarrhea viruses were studied using Tween 80, chloroform, trichlorotrifluoroethane and tri (n-butyl) phosphate. Attenuated A and virulent Ames strains of hog cholera virus were employed. Moreover, the NADL PK-15 cell culture adopted strain and low cell culture passaged Purdue strain of bovine viral diarrhea virus were used. These viruses were reacted with 2,500 micrograms/ml of Tween 80 for one hour at 37 degrees C. When attenuated A and virulent Ames strains of hog cholera virus with titers greater than 10(6) and 10(5) plaque forming units respectively, were reacted with Tween 80 the titer of each strains was reduced by approximately 10(4) plaque forming units of virus. When either strain of bovine viral diarrhea virus was reacted with Tween 80, virus was not detected.