Automated Bioanalytical Workflow for Ligand Binding-Based Pharmacokinetic Assay Development

The growth of therapeutic monoclonal antibodies (mAbs) continues to accelerate due to their success as treatments for many diseases. As new therapeutics are developed, it is increasingly important to have robust bioanalytical methods to measure the pharmacokinetics (PK) of circulating therapeutic mAbs in serum. Ligand-binding assays such as enzyme-linked immunosorbent assays (ELISAs) with anti-idiotypic antibodies (anti-IDs) targeting the variable regions of the therapeutic antibody are sensitive and specific bioanalytical methods to measure levels of therapeutic antibodies in a biological matrix. However, soluble circulating drug mAb targets can interfere with the anti-IDs binding to the therapeutic mAb, thereby resulting in an underestimation of total drug concentration. Therefore, in addition to a high binding affinity for the mAb, the selection of anti-IDs and the assay format that are not impacted by soluble antigens and have low matrix interference is essential for developing a robust PK assay. Standardized automated approaches to screen and select optimal reagents and assay formats are critical to increase efficiency, quality, and PK assay robustness. However, there does not exist an integrated screening and analysis platform to develop robust PK assays across multiple formats. We have developed an automated workflow and scoring platform with multiple bioanalytical assay parameters that allow for ranking of candidate anti-IDs. A primary automated indirect electrochemiluminescence (ECL) was utilized to shortlist the anti-IDs that were selected for labeling and screening in pairs. A secondary screen using an ECL sandwich assay with labeled-anti-ID pairings was used to test multiple PK assay formats to identify the best anti-ID pairing/PK assay format. We developed an automated assay using fixed plate maps combined with a human-guided graphical user interface-based scoring system and compared it to a data-dependent scoring system using Gaussian mixture models for automated scoring and selection. Our approach allowed for screening of anti-IDs and identification of the most robust PK assay format with significantly reduced time and resources compared with traditional approaches. We believe that such standardized, automated, and integrated platforms that accelerate the development of PK assays will become increasingly important for supporting future human clinical trials.

A Tiered Approach for Characterization to Ensure Quality, Reproducibility, and Long-Term Stability of Critical Reagents in Regulated Bioanalysis to Support PK/ADA/NAb Assays for Biologics and Vaccines Programs

The robustness of good laboratory practice and clinical data is reliant upon a clear understanding of the bioanalytical assays. One of the most important components of ligand-binding based assays is critical reagents used to directly or indirectly measure biologic markers or signals. High quality, reproducible, sustainable critical reagents through the development lifecycle could avoid unnecessary rework, multiple validations, cross-validations, and ensure consistency of the data. Numerous analytical methods (UPLC-size exclusion chromatography, cation exchange chromatography, biacore/octet, and high-resolution mass spectrometry) have been evaluated by using current critical reagents. A comprehensive analytical toolbox of biochemical and biophysical methods has been employed to evaluate the quality of critical reagents and explore potential issues if there are any. Moving forward, this "tiered approach" of critical reagents characterization will be used not only to establish critical quality attributes for new reagents but also to evaluate stability in support of reagents recertification.

Predictive factors for local control in primary and metastatic lung tumours after four to five fraction stereotactic ablative body radiotherapy: a single institution's comprehensive experience

AIMS

We report the outcomes of a large lung stereotactic ablative body radiotherapy (SABR) programme for primary non-small cell lung cancer (NSCLC) and pulmonary metastases. The primary study aim was to identify factors predictive for local control.

MATERIALS AND METHODS

In total, 311 pulmonary tumours in 254 patients were treated between 2008 and 2011 with SABR using 48-60 Gy in four to five fractions. Local, regional and distant failure data were collected prospectively, whereas other end points were collected retrospectively. Potential clinical and dosimetric predictors of local control were evaluated using univariate and multivariate analyses.

RESULTS

Of the 311 tumours, 240 were NSCLC and 71 were other histologies. The 2 year local control rate was 96% in stage I NSCLC, 76% in colorectal cancer (CRC) metastases and 91% in non-lung/non-CRC metastases. Predictors of better local control on multivariate analysis were non-CRC tumours and a larger proportion of the planning target volume (PTV) receiving ≥100% of the prescribed dose (higher PTV V100). Among the 45 CRC metastases, a higher PTV V100 and previous chemotherapy predicted for better local control.

CONCLUSIONS

Lung SABR of 48-60 Gy/four to five fractions resulted in high local control rates for all tumours except CRC metastases. Covering more of the PTV with the prescription dose (a higher PTV V100) also resulted in superior local control.

International variability in the reimbursement of cancer drugs by publically funded drug programs

PURPOSE

Evaluate inter-country variability in the reimbursement of publically funded cancer drugs, and identify factors such as cost containment measures that may contribute to variability.

METHODS

As of February 28, 2010, licensed indications for 10 cancer drugs (bevacizumab, bortezomib, cetuximab, erlotinib, imatinib, pemetrexed, rituximab, sorafenib, sunitinib, and trastuzumab) were obtained from the drug registries of 6 licensing authorities corresponding to 13 countries or regions: Australia, Canada (Ontario), England, Finland, France, Italy, Germany, Japan, New Zealand, the Netherlands, Scotland, Sweden, and the United States (Medicare Parts B and D). Number of licensed indications reimbursed by public payers and the use of cost containment measures were obtained by survey of health authorities involved in reimbursement and through public documents.

RESULTS

The 48 identified licensed indications varied between agencies (range: 36-44 indications). Finland, France, Germany, Sweden, and the United States reimbursed the highest percentage of indications (range: 90%-100%). Canada (54%), Australia (46%), Scotland (40%), England (38%), and New Zealand (25%) reimbursed the least. All 5 countries with the lowest rate of reimbursement incorporated a cost-effectiveness analysis into reimbursement decisions and rejected submissions for reimbursement mainly because of lack of cost effectiveness; in New Zealand, lack of cost effectiveness was the second leading cause of rejection after excessive cost. In 9 countries, risk-sharing agreements were used to contain costs. Indications initially not recommended for reimbursement (9 in Australia, 5 in Canada, and 3 in England, New Zealand, and Scotland) were subsequently approved with risk-sharing agreements or special pricing arrangements.

CONCLUSIONS

Reimbursement of publically funded cancer drugs varies globally. The cause is multifactorial.

Utility of serial urinalyses and urinary cytology in the evaluation of patients with microscopic haematuria

BACKGROUND

Serial urinalyses have been advocated when haematuria is suspected.

OBJECTIVE

To determine the utility of serial urinalyses and urinary cytology in patients presenting for evaluation of microscopic haematuria.

METHODS

Eighty-five patients with the diagnosis of microscopic haematuria were evaluated at a tertiary-care hospital. All patients had a comprehensive urologic evaluation. Clinic and hospital records were reviewed for key factors (e.g., demographic, pathology, radiologic findings and operative findings).

RESULTS

One hundred ninety total urinalyses were reviewed. Eighty-eight (46%) urinalyses were classified as normal, 87 (46%) as haematuria (> 3 RBC/hpf), and 15 (8%) as pyuria/ bacteriuria. The initial urinalysis detected haematuria in 95% of the patients. The addition of the second and third urinalyses detected haematuria in the remaining 5% of the patients with haematuria. Aetiologic factors for microscopic haematuria include urolithiasis 15 (18%), infection 9 (11%) and bladder lesion/tumor 6 (7%). In this setting of microscopic haematuria, urinary cytology was not able to detect any of the five documented bladder tumors. Fifty-seven percent of patients had a negative haematuria evaluation.

CONCLUSION

In the evaluation of the patient with microscopic haematuria, serial urinalyses may have a low yield. Further prospective studies are needed to further evaluate serial urinalyses in this cohort.

Paediatric retinal detachment: comparison of high myopia and extreme myopia

AIMS

To compare the clinical features and surgical outcomes of paediatric retinal detachment (RD) in high myopia and extreme myopia.

METHODS

The clinical charts of 107 children who experienced RD and had a spherical equivalent (SE) of at least 6.00 dioptres (D) were reviewed. The patients were separated into a high myopia group (SE -6.0 to -10.0 D) and extreme myopia group (SE >-10.0 D). RD characteristics and outcomes were compared between these two groups.

RESULTS

There were significant differences between the two groups in total RD (p<0.001), the presence of posterior staphyloma (p<0.001) and some types of breaks. More eyes in the extreme myopia group required vitrectomy after the initial RD repair. In the high myopia group, retinal reattachment was achieved in 79 eyes (97.5%) at the end of the intervention, whereas in the extreme myopia group, retinal reattachment was achieved in 22 eyes (73.3%). Multiple logistic regression showed that a higher refractive error was the only negative predictor of surgical outcome (p = 0.026).

CONCLUSION

Due to differences in aetiologies, clinical characteristics, required surgical procedure after initial repair, surgical and functional outcomes, paediatric RD with extreme myopia should be addressed differently from paediatric RD with high myopia.

The Hong Kong diastolic heart failure study: a randomised controlled trial of diuretics, irbesartan and ramipril on quality of life, exercise capacity, left ventricular global and regional function in heart failure with a normal ejection fraction

BACKGROUND

Although heart failure with a preserved or normal ejection fraction (HFNEF or diastolic heart failure) is common, treatment outcomes on quality of life and cardiac function are lacking. The effect of renin-angiotensin blockade by irbesartan or ramipril in combination with diuretics on quality of life (QoL), regional and global systolic and diastolic function was assessed in HFNEF patients.

METHODS

150 patients with HFNEF (LVEF >45%) were randomised to (1) diuretics alone, (2) diuretics plus irbesartan, or (3) diuretics plus ramipril. QoL, 6-minute walk test (6MWT) and Doppler echocardiography were performed at baseline, 12, 24 and 52 weeks.

RESULTS

The QoL score improved similarly in all three groups by 52 weeks (-46%, 51%, and 50% respectively, all p<0.01), although 6MWT increased only slightly (average +3-6%). Recurrent hospitalisation rates were equal in all groups (10-12% in 1 year). At 1 year, LV dimensions or LVEF had not changed in any group, though both systolic and diastolic blood pressures were lowered in all three groups from 4 weeks onwards. At baseline both mean peak systolic (Sm) and early diastolic (Em) mitral annulus velocities were reduced, and increased slightly in the diuretic plus irbesartan (Sm 4.5 (SEM 0.17) to 4.9 (SEM 0.16) cm/sec; Em 3.8 (SEM 0.25) to 4.2 (SEM 0.25) cm/sec) and ramipril (Sm 4.5 (SEM 0.24) to 4.9 (SEM 0.20) cm/sec; Em 3.3 (SEM 0.25) to 4.04 (SEM 0.32) cm/sec) groups (both p<0.05). NT-pro-BNP levels were raised at baseline (595 (SD 905) pg/ml; range 5-4748) and fell in the irbesartan (-124 (SD 302) pg/ml, p = 0.01) and ramipril (-173 (SD 415) pg/ml, p = 0.03) groups only.

CONCLUSIONS

In this typically elderly group of HF patients with normal LVEF, diuretic therapy significantly improved symptoms and neither irbesartan nor ramipril had a significant additional effect. However, diuretics in combination with irbesartan or ramipril marginally improved LV systolic and diastolic longitudinal LV function, and lowered NT-proBNP over 1 year.

Characterization of Plasmodium falciparum cGMP-dependent protein kinase (PfPKG): Antiparasitic activity of a PKG inhibitor☆

Cyclic GMP-dependent protein kinase (PKG) has been biochemically and genetically validated in Toxoplasma gondii as a primary target responsible for the antiparasitic activity of the trisubstituted pyrrole 4-[2-(4-fluorophenyl)-5-(1-methylpiperidine-4-yl)-1H pyrrol-3-yl] pyridine (Compound 1) [Biftu T, Feng D, Ponpipom M, et al. Synthesis and SAR of 2,3-diarylpyrrole inhibitors of parasite cGMP-dependent protein kinase as novel anticoccidial agents. Bioorg Med Chem Lett 2005;15:3296-301; Gurnett AM, Liberator PA, Dulski PM, et al. Purification and molecular characterization of cGMP-dependent protein kinase from Apicomplexan parasites. A novel chemotherapeutic target. J Biol Chem 2002;277:15913-22; Donald RGK, Allocco J, Singh SB, et al. Toxoplasma gondii cyclic GMP-dependent kinase: Chemotherapeutic targeting of an essential parasite protein kinase. Eukaryotic Cell 2002;1:317-28; Nare B, Allocco J, Liberator PA, Donald RGK. Evaluation of a cyclic GMP-dependent protein kinase inhibitor in treatment of murine Toxoplasmosis: Gamma interferon is required for efficacy. Antimicrob Agents Chemother 2002;46:300-7]. Compound 1 inhibits the growth of several related protozoan parasites of the subphylum Apicomplexa. Native PKG activity has been partially purified by cGMP-affinity and MonoQ ion exchange chromatography from Plasmodium falciparum (PfPKG). Biochemical fractions enriched for a 98kDa protein detected using anti-PKG antisera, contain cGMP-induced protein kinase activity that is sensitive to inhibition by Compound 1. To enable a more thorough characterization of PfPKG we expressed a synthetic cDNA incorporating T. gondii codon preference (Pf(Tg)PKG) in T. gondii parasites. The protein kinase activity of purified recombinant Pf(Tg)PKG is stimulated by cGMP, with significant cooperativity as demonstrated by a Hill coefficient of 2. Both substrate preference and inhibition of Pf(Tg)PKG kinase activity by Compound 1 are similar to that seen with native PfPKG, as well as PKG enzymes from Eimeria spp. and T. gondii. We conclude that PfPKG has biochemical and pharmacological properties that are similar to previously characterized apicomplexan PKG enzymes. Compound 1 is active against blood cell stages of P. falciparum cultured in vitro. In a Plasmodium berghei mouse model of infection, Compound 1 delays the onset of parasitemia but does not cure the parasite infection.

Human herpesvirus 6 reactivation and encephalitis in allogeneic bone marrow transplant recipients

To determine whether receipt of an investigational anti-CD3 monoclonal antibody (BC3) increased the risk of human herpesvirus 6 (HHV-6) reactivation and development of encephalitis in bone marrow transplant (BMT) recipients, persons who had and had not received BC3 were compared. Odds of HHV-6 reactivation were higher among BC3 recipients than among control patients (odds ratio, 2.5; 95% confidence interval [CI], 1.3-4.7). In addition, BC3 recipients were more likely than control patients to develop encephalitis (risk ratio [RR], 3.5; 95% CI, 1.3-9.5), and this association followed a BC3 dose-dependent relationship (P=.03, by Mantel-Haenszel chi(2) test). In a multivariable model, HHV-6 reactivation and receipt of BC3 were associated with increased risk of encephalitis (RR, 5.4; 95% CI, 1.9-15.3, and RR, 3.3; 95% CI, 1.2-9.1, respectively). In conclusion, both HHV-6 reactivation and receipt of BC3 for prophylaxis of acute graft-versus-host disease independently increased the risk of encephalitis in allogeneic BMT recipients. Prospective studies to better define the relationship between HHV-6 reactivation and encephalitis in allogeneic BMT recipients are warranted.

Anti-ischemic action of estrogen-progestogen continuous combined hormone replacement therapy in postmenopausal women with established angina pectoris: a randomized, placebo-controlled, double-blind, parallel-group trial

The benefit of treating postmenopausal women with established cardiovascular disease with combined estrogen-progestogen hormone replacement therapy (HRT) is controversial. This study investigated the effect of treatment with estradiol and norethisterone acetate on exercise tolerance and on the frequency and severity of ischemic attacks in postmenopausal women with stable angina pectoris. A total of 74 Chinese women were recruited for this 16-week double-blind, placebo-controlled trial. They were randomly allocated into two groups; one group received placebo/placebo/placebo and the other group received placebo/estrogen-progestogen/placebo. Estrogen-progestogen continuous combined HRT increased both time to 1-mm ST depression (99.1 s, p < 0.05) compared with a mean decrease of 22.9 s with placebo (p < 0.05), and total exercise duration also showed a significant increase (32.7 s, p < 0.05) after treatment compared with placebo (2.5 s, p < 0.05). In addition, the total number of ischemic events/24 h during ambulatory electrocardiographic monitoring decreased by 0.82 events after treatment (p < 0.05) compared with an increase in the placebo group (0.94), a highly significant difference (p = 0.006). These results suggest that the administration of this particular combined hormone replacement preparation may have a beneficial effect on myocardial ischemia in postmenopausal women with established coronary disease.

Multiple founder effects in spinal and bulbar muscular atrophy (SBMA, Kennedy disease) around the world

SBMA (spinal and bulbar muscular atrophy), also called Kennedy disease, is an X-chromosomal recessive adult-onset neurodegenerative disorder caused by death of the spinal and bulbar motor neurones and dorsal root ganglia. Patients may also show signs of partial androgen insensitivity. SBMA is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene on the X-chromosome. Our previous study suggested that all the Nordic patients with SBMA originated from an ancient Nordic founder mutation, but the new intragenic SNP marker ARd12 revealed that the Danish patients derive their disease chromosome from another ancestor. In search of relationships between patients from different countries, we haplotyped altogether 123 SBMA families from different parts of the world for two intragenic markers and 16 microsatellites spanning 25 cM around the AR gene. The fact that different SBMA founder haplotypes were found in patients from around the world implies that the CAG repeat expansion mutation has not been a unique event. No expansion-prone haplotype could be detected. Trinucleotide diseases often show correlation between the repeat length and the severity and earlier onset of the disease. The longer the repeat, the more severe the symptoms are and the onset of the disease is earlier. A negative correlation between the CAG repeat length and the age of onset was found in the 95 SBMA patients with defined ages at onset.

Effects of dopamine antagonists in human eye accommodation

The purpose of this study was to evaluate the effects of dopamine antagonists in accommodation of the human eye. The dopamine antagonist drugs used in this experiment include 0.5% metoclopramide and 0.25% droperidol. Eighteen healthy subjects were enrolled; they were randomly assigned, in double-masked fashion, to receive topical administration of a single drop of either 0.5% metoclopramide or 0.25% droperidol in one eye, with the fellow eye receiving isotonic saline as control. The accommodative abilities of both eyes were measured before instillation, and also at 3 and 6 hr after instillation of drugs, respectively. We studied the latency of reaction, the rate of accommodation, the average accommodative power, the rate of recovering and the total recovering time as the five parameters for evaluating the accommodative ability of each eye. The results showed that there were significant changes in two parameters: the rate of accommodation and rate of recovering, whereas there were no significant changes in the other three parameters: latency of accommodation, average power of accommodation and total recovering time. In conclusion, the dopamine antagonists may have some effects on the rate of accommodation but not the degree of accommodation. Further studies with higher concentrations of these dopamine antagonists on dose-response relationships are needed before exact drug efficacy can be drawn.

Efficient neurophysiologic selection of X-linked Charcot-Marie-Tooth families: ten novel mutations

OBJECTIVE

To devise a neurophysiologic strategy to select X-linked Charcot-Marie-Tooth neuropathy syndrome (CMTX) families for connexin 32 mutation screening.

BACKGROUND

Once the common chromosome 17 DNA duplication (CMT1A syndrome) has been excluded, clinical features are not sufficiently distinctive to select which of three genes (PMP22, Po, or connexin 32) should be screened for mutations.

DESIGN

The yield of connexin 32 mutations was compared in possible CMTX families with clinical and genetic features of CMTX and probable CMTX families, defined by additional characteristic neurophysiologic features of CMTX. Of 232 CMT families with median motor nerve conduction velocities below 50 m/second (s) in affected men, 50 were found to have no CMT1A duplication and a pattern of inheritance compatible with CMTX (no man-to-man inheritance of CMT). These families were divided into 23 probable CMTX families (defined as having electrophysiologic indicators of CMTX), 23 possible CMTX families (with no neurophysiologic features of CMTX), and five unlikely CMTX families (with normal brainstem evoked auditory potentials [BAEPs]).

RESULTS

The yield of mutations in the whole group was 25 mutations in 51 families (50%). Most probable CMTX families (21 of 23; 91%) had connexin 32 coding region mutations. Included in this group were 14 families with obligate female carriers; 11 of these had intermediate conduction velocities (>42 m/s) and nine (81%) had connexin 32 mutations. Only 3 of 23 (13%) possible CMTX families had connexin 32 mutations. One of five families with normal BAEPs in affected men had a connexin 32 mutation, and one had a Po Ala112Val mutation. Seventeen different mutations were found among 24 families, including 10 previously undescribed mutations (Leu9Trp, Ile28Thr, Ile30Thr, Ile127Met, Leu131Pro, Tyr154 stop, Pro158Ala, one base deletion of codon 158 causing stop at codon 195, Val192Phe, and Leu239Ile).

CONCLUSIONS

The yield of connexin 32 mutations can be increased from approximately 6% of all CMT type I families to 91% of nonduplicated nondominant families with characteristic electrophysiologic changes of CMTX.

The correlation of clinical phenotype in Friedreich ataxia with the site of point mutations in the FRDA gene

Most cases of Friedreich ataxia (FRDA) are due to expansions of a GAA trinucleotide repeat sequence in the FRDA gene coding for frataxin, a protein of poorly understood function which may regulate mitochondrial iron transport. However, between 1% and 5% of mutations are single base changes in the sequence of the FRDA gene, causing missense, nonsense, or splicing mutations. We describe three new mutations, IVS4nt2 (T to G), R165C, and L182F, which occur in patients in association with GAA expansions. These cases, and a further five reported cases of point mutations causing FRDA, demonstrate that splicing, nonsense, or initiation codon mutations (which cause a complete absence of functional frataxin) are associated with a severe phenotype. Missense mutations, even in highly evolutionally conserved amino acids, may cause a mild or severe phenotype.

Three novel mutations and two variants in the gene for Cu/Zn superoxide dismutase in familial amyotrophic lateral sclerosis

Autosomal dominant inheritance is exhibited by about 10% of cases of amyotrophic lateral sclerosis (ALS), a paralytic disorder characterized by the death of motor neurons in the brain and spinal cord. A subgroup of these familial cases are linked to mutations in the gene which codes for Cu/Zn superoxide dismutase (SOD1). We report three additional mutations occurring in the SOD1 gene in ALS patients and two single base pair variant changes. The single base pair change in an ALS family causes a glycine 93 to valine substitution, which is the fifth distinct amino acid change reported for the glycine 93 residue. One missense mutation in exon 5 would substitute neutral valine for the negatively-charged aspartate 124 (aspartate 124 to valine). An individual with an apparently sporadic case of ALS carries a three base pair deletion in exon 5 of the SOD1 gene. These three mutations bring to 38 the total number of distinct SOD1 mutations associated with familial ALS.

Ambulatory parathyroidectomy for primary hyperparathyroidism

OBJECTIVE

To evaluate whether the combined application of preoperative localization and intraoperative monitoring of intact parathyroid hormone (iPTH) levels could facilitate safe outpatient parathyroidectomy.

DESIGN

Consecutive patients, who had no antecedent social or medical conditions mandating hospitalization, were prospectively offered ambulatory parathyroidectomy with a mean follow-up of 7 months (range, 1-25 months).

SETTING

Tertiary care referral center

PATIENTS

From 85 patients who had primary hyperparathyroidism with hypercalcemia and elevated iPTH levels, 57 were offered outpatient parathyroidectomy. Nineteen patients were asymptomatic, 3 had hypercalcemic crisis, and the others gave a history of renal stones or had complaints consistent with bone disease.

INTERVENTIONS

Technetium Tc 99m sestamibi scintiscans were used for preoperative localization. Monitoring iPTH levels during parathyroidectomy quantitatively assured the surgeon (G.L.I. only) when all hyperfunctioning glands were excised.

MAIN OUTCOME MEASURE

The number of patients without complications and with short operative times who were discharged without hospital admission or overnight stay.

RESULTS

The combination of preoperative localization of abnormal parathyroid glands and a decline in circulating iPTH levels predicting postoperative normocalcemia after excision of all hyperfunctioning glands resulted in successful parathyroidectomy in 84 of 85 patients. A decreased operative time (average, 52 minutes) with minimal neck dissection permitted outpatient parathyroidectomy in 42 of 57 eligible patients.

CONCLUSIONS

The combination of preoperative parathyroid scintiscan localization and iPTH level monitoring during surgery permitted successful parathyroidectomy in an ambulatory setting in half of a consecutive series of patients with primary hyperparathyroidism. The safety, success, and likely cost savings of this approach suggest wider application.

Right ventricular diastolic dysfunction in heart failure

BACKGROUND

Left ventricular (LV) diastolic dysfunction is common in heart failure and is an important predictor of prognosis and mortality. Less attention has been paid to right ventricular (RV) diastolic function. In this study, we compared RV diastolic function in a large cohort of patients with heart failure (HF) with two groups: patients with pulmonary hypertension and normal LV function (the PHT group) and normal subjects.

METHODS AND RESULTS

Transtricuspid and pulmonary artery flow were assessed by two-dimensional Doppler echocardiography at maximum inspiration and expiration in 185 subjects: 114 symptomatic HF patients (ejection fraction < 0.5), 31 PHT patients (pulmonary artery systolic pressure > 40 mm Hg), and 40 normal subjects. A subset was matched for age and heart rate. The results showed a high prevalence of RV diastolic abnormalities: HF patients had lower tricuspid E-A ratios, lower peak E-wave velocity, and prolonged RV isovolumic relaxation time (all P< .0001). Tricuspid E-wave deceleration time was significantly shorter only in those who had an LV restrictive filling pattern. The PHT group had similar findings. Compared with a normal range, more than half of the patients had lower tricuspid E-A ratios (HF, 55%; PHT, 69%), and 61% of HF and 58% of PHT patients had a prolonged RV isovolumic relaxation time. In the PHT group, RV diastolic parameters (E-wave deceleration time, E-A ratio, and isovolumic relaxation time) correlated significantly with pulmonary artery systolic pressure (P< .05). In the HF group, however, only tricuspid E-wave deceleration time correlated significantly with pulmonary artery systolic pressure, and HF patients with normal pulmonary artery systolic pressures had significantly lower tricuspid E-A ratios and prolonged RV isovolumic relaxation times compared with normal subjects. A close correlation existed between individual RV and LV diastolic parameters, suggesting that LV diastolic dysfunction may directly affect RV function, but there was no relation between LV size or systolic function and RV diastolic dysfunction.

CONCLUSIONS

RV diastolic function is frequently abnormal in HF patients, and this is not related to elevated pulmonary artery systolic pressure alone, although high pulmonary artery pressure by itself also is associated with impaired RV diastolic function. Assessment of the role of right ventricular diastolic function in determining the symptoms and prognosis of heart failure is warranted.

Artifactual staining of monoclonal antibodies in two-color combinations is due to an immunoglobulin in the serum and plasma

Two-color whole blood lysis is the assay of choice for lymphocyte immunophenotyping because of the additional information it provides. Recently, artifactual double-staining of some specimens has been observed with this assay. In these cases, the samples appear to be uncompensated for spectral overlap or to inappropriately coexpress two antigens simultaneously. This artifact can result in the apparent coexpression of CD4 and CD8 (observed in lymphoblastic processes) or of CD5 and CD20 (characteristic of chronic lymphocytic leukemia) in normal persons, leading to an erroneous diagnosis. Using plasma, serum, or immunoglobulin preparations from donors who exhibit this artifact we sought to determine 1) the source of the artifact and 2) ways to overcome it. This staining is apparently due to an immunoglobulin in the donors' serum and plasma which does not have specific reactivity with mouse immunoglobulin. Washing whole blood samples or blocking with mouse immunoglobulin is a convenient way of avoiding this artifact.