A randomized, cross-over study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of milvexian with single and dual antiplatelet therapy in healthy participants

Background

According to scientific evidence, modulation of Factor XI (FXI) function may provide a novel mechanism for systemic anticoagulation without increasing the risk of clinically relevant bleeding in a variety of conditions associated with a high risk of thrombotic events. Milvexian (BMS-986177/JNJ-70033093) is an oral small molecule that binds reversibly to and inhibits the active form of FXI (FXIa) with high affinity and selectivity. Depending on the patient population, milvexian is expected to provide benefit to patients as replacement or add on therapy to current guideline-recommended antithrombotic agents which include aspirin and/or clopidogrel.

Purpose

This DDI study aimed to investigate the safety and to identify possible pharmacokinetic (PK) or pharmacodynamic (PD) interaction of milvexian when co-administered with aspirin and/or clopidogrel.

Methods

The study consisted of 3 parts, each of which was a single DDI study using a randomized, 3-period, 3-treatment crossover design. Six unique treatment sequences were utilized in the study. Milvexian was placebo controlled and blinded when co-administered with aspirin and clopidogrel (Part 1), with clopidogrel (Part 2), or with aspirin (Part 3). In each case the subjects crossed over to milvexian monotherapy. Subjects were randomly assigned into 1 part of the study only.

Results

Overall, multiple dose milvexian 200 mg given BID for 5 days with and without dual antiplatelet therapy (clopidogrel given as 300 mg on Day 1 followed by 4 days of 75 mg clopidogrel, and aspirin 325 mg once daily given for 5 days) was safe and well tolerated. There were 8 mild bleeding adverse events (AEs) reported from 5 subjects in various treatment groups; no trend towards increased bleeding potential was observed when milvexian was co-administered with dual antiplatelet therapy or separately with aspirin or clopidogrel. After co-administration of aspirin and clopidogrel with milvexian, peak (Cmax) and total exposure [AUC(TAU)] of milvexian were reduced 17% and 15%, respectively, on Day, 1 but were not changed on Day 5, compared to milvexian administered alone. After co-administration of clopidogrel or aspirin separately with milvexian, peak and total exposures of milvexian were not changed, compared to milvexian administered alone. Exposure-dependent prolongation of activated partial thromboplastin time (aPTT) and reduction of Factor XI clotting activity (FXIc) were observed with milvexian administration. Effects were similar when milvexian was administered alone or in combination with aspirin and/or clopidogrel.

Conclusion

This Phase 1 study in healthy adults demonstrated administration of milvexian alone or in combination with aspirin and/or clopidogrel was not associated with a trend towards AE's including bleeding. Milvexian steady-state exposure and PD effects were similar when milvexian was administered alone or in combination with aspirin and/or clopidogrel.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Bristol Myers Squibb and Janssen Pharmaceuticals

Causes of death in patients with atrial fibrillation and a recent acute coronary syndrome or percutaneous coronary intervention: insights from the AUGUSTUS trial

Background

Patients with atrial fibrillation (AF) and concomitant coronary artery disease are at increased risk for poor outcomes. Less is known about specific causes of death in this population.

Methods

We describe specific causes of death among patients with AF and acute coronary syndrome and/or percutaneous coronary intervention included in the AUGUSTUS trial and followed for 6 months. An independent clinical events committee, blinded to treatment assignment, adjudicated cause of death according to pre-defined criteria. The association between baseline factors and all-cause death was evaluated using Cox proportional hazards modeling.

Results

A total of 151 deaths occurred in 4614 patients and were adjudicated as follows: 111 (73.5%) deaths due to cardiovascular (CV) causes and 40 (26.5%) due to non-CV causes. The most common cause of CV death was sudden death (n=39 [35.1%]), followed by myocardial infarction (n=29 [26.1%]) and heart failure (n=24 [21.6%]). The most common causes of non-CV death were infection (n=11 [27.5%]), bleeding (n=8 [20.0%]), and malignancy (n=5 [12.5%]). Increasing age, African American race, history of heart failure, treatment with diuretics, and lower body weight were associated with an increased risk of all-cause death (Table).

Conclusions

Among patients with AF and coronary artery disease, cardiovascular causes were responsible for the majority of deaths within 6 months. Our findings provide relevant information to inform the design of future studies in this population.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): AUGUTUS was funded by Bristol Myers Squibb and Pfizer.

Canadian Real-World Outcomes of Omnipod Initiation in People with Type 1 Diabetes (COPPER study): Evidence from the LMC Diabetes Registry

AIMS

To investigate real-world clinical outcomes in adults with type 1 diabetes who initiated the Omnipod Insulin Management System (Insulet Corp., Acton, MA, USA) compared to a matched cohort who maintained multiple daily injection therapy.

METHODS

This retrospective observational study used data from the Canadian LMC Diabetes Registry. Adults with type 1 diabetes who switched from multiple daily injections to the Omnipod system as usual standard of care between January 2011 and April 2019 were matched to a cohort of adults with type 1 diabetes who maintained multiple daily injection therapy, using propensity-score matching. The primary outcome was change in HbA_1c at 3- to 6-month follow-up.

RESULTS

Propensity-score matching resulted in a final analytical cohort of 286 individuals (143/cohort). HbA_1c in the Omnipod cohort was reduced by a mean ± sd of -3 ± 10 mmol/mol (-0.2 ± 1.0%; P = 0.005) with no change in the MDI cohort [0 ± 10 mmol/mol (0.0 ± 1.0%); P = 0.74]. HbA_1c change was seen only in persons with baseline HbA_1c ≥75 mmol/mol (≥9.0%) [Omnipod cohort: -15 ± 12 mmol/mol (-1.4 ± 1.1%); P < 0.001] with a between-treatment difference [mean (95% CI)] of -12 (-18, -6) mmol/mol [-1.1 (-1.6, -0.5) %, P < 0.001]. The median total daily dose of insulin was lower following Omnipod initiation (baseline 0.63 U/kg vs follow-up 0.53 U/kg; P < 0.001), with no change in the MDI cohort (baseline 0.68 U/kg vs follow-up 0.67 U/kg; P = 0.23).

CONCLUSIONS

Adults with type 1 diabetes who initiated use of the Omnipod system in a real-world clinical setting had lower HbA_1c and total daily dose of insulin at 3- to 6-month follow-up compared to a matched cohort of adults who maintained multiple daily injection therapy. A treatment difference in HbA_1c change was seen only in people with baseline HbA_1c ≥ 75 mmol/mol (9.0%). (Clinical trials registration: NCT04226378).

Choice of P2Y12 inhibitor and clinical outcomes in the AUGUSTUS study: support for an individualised approach

Background

AUGUSTUS randomized patients with atrial fibrillation and ACS and/or PCI to apixaban or VKA and aspirin or placebo for 6 months on background P2Y12 inhibitor.

Purpose

To characterise the clinical outcomes in patients receiving clopidogrel or ticagrelor.

Methods

Patients enrolled in AUGUSTUS (n=4614) were grouped by P2Y12 inhibitor at randomization. Baseline characteristics were compared among groups. Rates of ISTH major or CRNM bleeding, definite/probable stent thrombosis (ST), stroke, MI, and death or ischaemic event were quantified and treatment groups were compared according to treatment with clopidogrel or ticagrelor.

Results

At randomization, patients were treated with clopidogrel (n=4165), ticagrelor (n=280), prasugrel (n=51) or no P2Y12 inhibitor (n=118). Median ages were 71, 69, 66 and 72 years (P&lt;0.001). Ticagrelor and prasugrel were more commonly used in PCI-managed ACS (53% and 55%) whilst clopidogrel or no P2Y12 inhibitor was more common in medically-managed ACS (25% and 36%); elective PCI was the index event in 37–41% for each group. Irrespective of P2Y12 inhibitor used, bleeding risk was lower with apixaban vs. VKA and higher with aspirin vs. placebo (Table). ST rate was lowest but major/CRNM bleeding rate highest with ticagrelor + aspirin vs ticagrelor without aspirin or clopidogrel with or without aspirin.

Conclusions

Apixaban is safer than VKA regardless of P2Y12 inhibitor used. Dropping aspirin reduces bleeding but is associated with numerically higher ST rates regardless of P2Y12 inhibitor used. These data support current recommendations for preferential use of NOAC vs. VKA and individualised choice of P2Y12 inhibitor and timing of aspirin cessation after PCI according to the patient's risks of bleeding and stent thrombosis.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Bristol-Myers Squibb/Pfizer

Safety and efficacy of antithrombotic therapy according to stroke and bleeding risk in patients with atrial fibrillation and acute coronary syndrome or PCI: insights from AUGUSTUS

Background

The AUGUSTUS trial showed that patients with atrial fibrillation (AF) and acute coronary syndrome (ACS) and/or PCI treated with a P2Y12 inhibitor and apixaban resulted in less bleeding and comparable ischemic events compared with regimens that included a vitamin K antagonist (VKA), aspirin, or both. We assessed the effect of apixaban versus VKA and aspirin versus placebo according to patients' baseline risk of stroke and bleeding.

Methods

AUGUSTUS randomized 4614 patients in a two-by-two factorial design to open label apixaban or VKA and blinded aspirin or placebo. The primary endpoint was major or clinically relevant nonmajor (CRNM) bleeding over 6 months of follow-up. The effects were assessed stratified by baseline CHA2DS2-VASc and HAS-BLED score using Cox proportional hazards models.

Results

4386 patients were included for this analysis. The median age was 71 (64–77) years, 29.4% were female, 81.7% had a CHA2DS2-VASc score≥3, and 66.8% a HAS-BLED score≥3. As shown in the table, rates of bleeding were lower with apixaban (vs VKA) irrespective of baseline bleeding risk (p-value interaction: 0.23). Aspirin (vs placebo) was associated with increased bleeding irrespective of baseline risk (p-value interaction: 0.88). Apixaban use was associated with a lower risk of death or hospitalization without a significant interaction with stroke risk (p-value of interaction=0.53). No differences were found for ischemic outcomes.

Conclusion

An antithrombotic regimen including a P2Y12 inhibitor and apixaban is associated with less bleeding and hospitalization compared to a regimen with VKA, aspirin, or both with results consistent across CHA2DS2-VASc, and HAS-BLED scores. Our findings support the use of apixaban and a P2Y12 inhibitor without aspirin during the first 6 months for most patients with AF and ACS and/or PCI, regardless of stroke and bleeding risk.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): The Augustus trial was sponsored by Bristol-Myers Squibb and Pfizer, Inc

Rates and predictors of hypoglycaemia in 27 585 people from 24 countries with insulin-treated type 1 and type 2 diabetes: the global HAT study

AIMS

To determine the global extent of hypoglycaemia experienced by patients with diabetes using insulin, as there is a lack of data on the prevalence of hypoglycaemia in developed and developing countries.

METHODS

This non-interventional, multicentre, 6-month retrospective and 4-week prospective study using self-assessment questionnaire and patient diaries included 27 585 patients, aged ≥18 years, with type 1 diabetes (T1D; n = 8022) or type 2 diabetes (T2D; n = 19 563) treated with insulin for >12 months, at 2004 sites in 24 countries worldwide. The primary endpoint was the proportion of patients experiencing at least one hypoglycaemic event during the observational period.

RESULTS

During the prospective period, 83.0% of patients with T1D and 46.5% of patients with T2D reported hypoglycaemia. Rates of any, nocturnal and severe hypoglycaemia were 73.3 [95% confidence interval (CI) 72.6-74.0], 11.3 (95% CI 11.0-11.6) and 4.9 (95% CI 4.7-5.1) events/patient-year for T1D and 19.3 (95% CI 19.1-19.6), 3.7 (95% CI 3.6-3.8) and 2.5 events/patient-year (95% CI 2.4-2.5) for T2D, respectively. The highest rates of any hypoglycaemia were observed in Latin America for T1D and Russia for T2D. Glycated haemoglobin level was not a significant predictor of hypoglycaemia.

CONCLUSIONS

We report hypoglycaemia rates in a global population, including those in countries without previous data. Overall hypoglycaemia rates were high, with large variations between geographical regions. Further investigation into these differences may help to optimize therapy and reduce the risk of hypoglycaemia.

Sustained efficacy of insulin pump therapy compared with multiple daily injections in type 2 diabetes: 12-month data from the OpT2mise randomized trial

AIMS

To compare insulin pump therapy and multiple daily injections (MDI) in patients with type 2 diabetes receiving basal and prandial insulin analogues.

METHODS

After a 2-month dose-optimization period, 331 patients with glycated haemoglobin (HbA1c) levels ≥8.0% and ≤12% were randomized to pump therapy or continued MDI for 6 months [randomization phase (RP)]. The MDI group was subsequently switched to pump therapy during a 6-month continuation phase (CP). The primary endpoint was the between-group difference in change in mean HbA1c from baseline to the end of the RP.

RESULTS

The mean HbA1c at baseline was 9% in both groups. At the end of the RP, the reduction in HbA1c was significantly greater with pump therapy than with MDI (-1.1 ± 1.2% vs -0.4 ± 1.1%; p < 0.001). The pump therapy group maintained this improvement to 12 months while the MDI group, which was switched to pump therapy, showed a 0.8% reduction: the final HbA1c level was identical in both arms. In the RP, total daily insulin dose (TDD) was 20.4% lower with pump therapy than with MDI and remained stable in the CP. The MDI-pump group showed a 19% decline in TDD, such that by 12 months TDD was equivalent in both groups. There were no differences in weight gain or ketoacidosis between groups. In the CP, one patient in each group experienced severe hypoglycaemia.

CONCLUSIONS

Pump therapy has a sustained durable effect on glycaemic control in uncontrolled type 2 diabetes.

Pronounced reduction of postprandial glucagon by lixisenatide: a meta-analysis of randomized clinical trials

AIM

Glucagon-like peptide-1 (GLP-1) receptor agonists improve islet function and delay gastric emptying in patients with type 2 diabetes mellitus (T2DM). This meta-analysis aimed to investigate the effects of the once-daily prandial GLP-1 receptor agonist lixisenatide on postprandial plasma glucose (PPG), glucagon and insulin levels.

METHODS

Six randomized, placebo-controlled studies of lixisenatide 20 µg once daily were included in this analysis: lixisenatide as monotherapy (GetGoal-Mono), as add-on to oral antidiabetic drugs (OADs; GetGoal-M, GetGoal-S) or in combination with basal insulin (GetGoal-L, GetGoal-Duo-1 and GetGoal-L-Asia). Change in 2-h PPG and glucose excursion were evaluated across six studies. Change in 2-h glucagon and postprandial insulin were evaluated across two studies. A meta-analysis was performed on least square (LS) mean estimates obtained from analysis of covariance (ANCOVA)-based linear regression.

RESULTS

Lixisenatide significantly reduced 2-h PPG from baseline (LS mean difference vs. placebo: -4.9 mmol/l, p < 0.001) and glucose excursion (LS mean difference vs. placebo: -4.5 mmol/l, p < 0.001). As measured in two studies, lixisenatide also reduced postprandial glucagon (LS mean difference vs. placebo: -19.0 ng/l, p < 0.001) and insulin (LS mean difference vs. placebo: -64.8 pmol/l, p < 0.001). There was a stronger correlation between 2-h postprandial glucagon and 2-h PPG with lixisenatide than with placebo.

CONCLUSIONS

Lixisenatide significantly reduced 2-h PPG and glucose excursion together with a marked reduction in postprandial glucagon and insulin; thus, lixisenatide appears to have biological effects on blood glucose that are independent of increased insulin secretion. These effects may be, in part, attributed to reduced glucagon secretion.

Efficacy and safety of lixisenatide once daily versus placebo in type 2 diabetes insufficiently controlled on pioglitazone (GetGoal-P)

AIMS

To compare the efficacy and safety of once-daily prandial lixisenatide with placebo in type 2 diabetes mellitus (T2DM) insufficiently controlled by pioglitazone ± metformin.

METHODS

This randomized, double-blind study included a 24-week main treatment period and a ≥52-week variable extension period. Patients were randomized 2 : 1 to receive lixisenatide 20 µg once daily or placebo. The primary endpoint was change in glycated haemoglobin (HbA1c) at week 24.

RESULTS

In total, 484 patients were randomized: 323 to lixisenatide; 161 to placebo. After 24 weeks, lixisenatide once daily significantly improved HbA1c (-0.56% vs. placebo; p < 0.0001) and increased the proportion of patients achieving HbA1c <7% compared with placebo (52.3% vs. 26.4%, respectively; p < 0.0001) and significantly improved fasting plasma glucose (-0.84 mmol/l vs. placebo; p < 0.0001). There was a small decrease in body weight with lixisenatide once daily and a small increase with placebo, with no statistically significant difference between the two groups. Overall, lixisenatide once daily was well tolerated, with a similar proportion of treatment-emergent adverse events (TEAEs) and serious TEAEs between groups (lixisenatide: 72.4% and 2.5%; placebo: 72.7% and 1.9%). Symptomatic hypoglycaemia rates were also relatively low in both groups (lixisenatide 3.4% and placebo 1.2%), with no severe episodes. Lixisenatide continued to be efficacious and well tolerated during the variable extension period.

CONCLUSIONS

Lixisenatide once daily significantly improved glycaemic control with a low risk of hypoglycaemia, and was well tolerated over 24 weeks and during the long-term, double-blind extension period in patients with T2DM insufficiently controlled on pioglitazone ± metformin.

Perceptions of parenting: individual differences and the effect of community

Neighborhood norms are an important determinant of beliefs and attitudes about parenting, and measuring changes in community norms is an important component of evaluating community-based programs for improving child outcomes. The purpose of this study was to determine whether or not a survey of community residents' perceptions of parenting could be used to measure community parenting norms and whether these perceptions differed by individual or community characteristics. Two community surveys with 870 and 914 respondents, respectively, were conducted in 3 low-income neighborhoods. Results indicated that perceptions of parenting could be measured reliably at the community level although it is important to consider the presence of multiple norms when using such measures. Furthermore, differences in perceptions of parenting associated with individual characteristics were markedly decreased when neighborhood characteristics were considered, suggesting that the association of individual characteristics with perceptions of parenting is confounded by neighborhood characteristics.

Newborn screening in Wisconsin: program overview and test addition

The prevention of congenital anomalies and their sequelae is an important public health objective. One strategy for preventing morbidity and mortality due to congenital disorders is Wisconsin's Newborn Screening Program. Wisconsin has been a national leader in newborn screening since its inception with phenylketonuria screening in 1966. Wisconsin's program is a collaborative effort of the State Maternal and Child Health Program, housed within the Division of Public Health of the Department of Health and Family Services; the State Laboratory of Hygiene; physicians and other health professionals; and families. After in-depth consideration, the Department recently approved the addition of 14 fatty acid oxidation disorders and organic acidemias. This paper provides an overview of the Newborn Screening Program and introduces the disorders that Wisconsin added to the newborn screening panel in April 2000. Technologic advances have provided Wisconsin with yet another tool to improve the health of its citizens and prevent significant morbidity and mortality.

Racial disparities in African American and white infant mortality United States and Wisconsin, 1980 to 1998

Infant mortality is a powerful indicator for assessing the health of a population, and the extent to which society invests in its children. This paper examines infant mortality trends in the United States and Wisconsin among the African American and white populations from 1980 to 1998. Data from the National Center for Health Statistics and Wisconsin Birth and Infant Death Reports were used to examine overall infant mortality trends from 1980 to 1998 for African American and white infants. The overall infant mortality rate in Wisconsin decreased steadily from 10.3 infant deaths per 1000 live births in 1980 to 7.2 in 1998. White infant mortality followed this trend, declining from 9.6 in 1980 to 5.6 in 1998. African American infant mortality has remained about the same since 1980 at 18 infant deaths per 1000 live births, even though the overall percentage of African American live births in Wisconsin increased from 6% in 1980 to 10% in 1998. The ratio of African American to white infant mortality rates in Wisconsin increased from 2 to 1 in 1980 to 3.2 to 1 in 1998. While the Wisconsin African American infant mortality rate remained even since 1980, the US rate declined from 22.2 in 1980 to 14.1 in 1998. The Wisconsin African American rate in 1998, 17.9, surpassed the national rate. The use of 5-year running averages to smooth out year-to-year fluctuations showed statistically significant declines in Wisconsin white infant mortality rates and no change in Wisconsin African American infant mortality rates. These trends show the importance for Wisconsin to sustain its current efforts to reduce black infant mortality. At the same time, Wisconsin-based research efforts to determine strategies and factors that work should continue and influence the future design of systems, programs, and policies to eliminate the disparity.

Photon diffusion coefficient in an absorbing medium

A number of investigators have recently claimed, based on both analysis from transport theory and transport-theory-based Monte Carlo calculations, that the diffusion coefficient for photon migration should be taken to be independent of absorption. We show that these analyses are flawed and that the correct way of extracting diffusion theory from transport theory gives an absorption-dependent diffusion coefficient. Experiments by two different sets of investigators give conflicting results concerning whether the diffusion coefficient depends on absorption. The discrepancy between theory and the earlier set of experiments poses an interesting challenge.

Nonlinear effects of localized absorption perturbations on the light distribution in a turbid medium

A theoretical model of photon propagation in a scattering medium is presented, from which algebraic formulas for the detector-reading perturbations (delta R) produced by one or two localized perturbations in the macroscopic absorption cross section (delta mu a) are derived. Examination of these shows that when delta mu a is titrated from very small to large magnitudes in one voxel, the curve traced by the corresponding delta R values is a rectangular hyperbola. Furthermore, while delta Rinfinity identical to lim delta mu a-->infinity delta R is dependent on the location of the detector with respect to the source and the voxel, the ratio delta R/ delta Rinfinity is independent of the detector location. We also find that when delta mu a is varied in two voxels simultaneously, the quantity delta R (delta mu a,1 [symbol: see text] delta mu a,2) is a bilinear rational function of the delta mu aS. These results apply not only in the case of steady-state illumination and detection but to time-harmonic measurements as well. The validity of the theoretical formulas is demonstrated by applying them to the results of selected numerical diffusion computations. Potential applications of the derived expressions to image-reconstruction problems are discussed.

Radiative transfer implies a modified reciprocity relation

The usual reciprocity relations of radiative transfer do not hold two points located in regions of different index of refraction. Modified reciprocity relations that involve the relative index are derived. The result has computational as well as theoretical consequences.

Optical imaging of anatomical maps derived from magnetic resonance images using time-independent optical sources

We present a model suitable for computing images of absorption cross sections of thick tissue structures illuminated at near infrared (NIR) wavelengths from tomographic projection data. Image reconstruction is accomplished by solving a system of linear equations derived from transport theory. Reconstruction results using different algebraic solvers are shown for anatomical maps of the breast, derived from magnetic resonance imaging data, containing two simulated pathologies, in which case qualitatively good reconstructions were obtained. Evaluation of magnetic resonance (MR) data to optimize NIR optical tomographic imaging methods and to assess the feasibility of a combined MR-optical measurement scheme is discussed.

Nodular hyperplasia in treated congenital goitrous hypothyroidism

Two patients with congenital goitrous hypothyroidism, treated since birth, are described. Each developed progressive nodular thyroid enlargement in adolescence, possibly related to ongoing thyroid stimulation due to slight and transient elevations of thyroid stimulating hormone (TSH) levels. The incidence and degree of persistent thyroid enlargement in these patients has not been well documented. If present in a significant number of patients despite appropriate L-thyroxine replacement, our therapeutic aims in congenital goitrous hypothyroidism may need to be modified to achieve TSH suppression, rather than normalization.

Triiodothyronine augmentation in the treatment of refractory depression. A meta-analysis

BACKGROUND

Several trials have addressed the efficacy of liothyronine sodium therapy in euthyroid, nonpsychotic depressed patients refractory to tricyclic antidepressant therapy. We undertook a meta-analysis of these trials.

METHODS

The MEDLINE database (1966 to May 1995) and published reference lists were examined for controlled clinical trials of triiodothyronine augmentation in euthyroid patients with refractory depression. Quality assessment and data abstraction were performed independently by two reviewers. Results were aggregated three ways: the relative response rate compared with controls, accepting each trial's definition of clinical response; absolute improvement in response rates; and improvements in depression scores, analyzed as continuous variables without a prespecified threshold for clinical response.

RESULTS

Aggregating eight studies with a total of 292 patients, patients treated with triiodothyronine augmentation were twice as likely to respond as controls (relative response, 2.09; 95% confidence interval [CI], 1.31 to 3.32; P = .002). This corresponded to a 23.2% absolute improvement in response rates (95% CI, 4.5% to 41.9%; P = .02). Improvements in depression scores were moderately large (standardized effect size, 0.62; P < .001). However, study quality was uneven, and results were statistically heterogeneous. Among the four randomized double-blind studies, pooled effects were not significant (relative response, 1.53; 95% CI, 0.70 to 3.35; P = .29), but one study with negative results accounted for most of the intertrial heterogeneity in results.

CONCLUSIONS

Triiodothyronine augmentation may be an effective empirical method of increasing response rates and decreasing depression severity scores in a subgroup of patients with depression refractory to tricyclic antidepressant therapy, but the total number of patients randomized was small, and additional placebo-controlled data are required for a definitive verdict. Since therapeutic trends now favor other drugs, future trials might usefully examine triiodothyronine augmentation with selective serotonin reuptake inhibitors or compare potentiation strategies, eg, lithium vs triiodothyronine, for managing refractory depression. Such trials would benefit from much larger sample sizes than those reviewed here.

Recovery of optical cross-section perturbations in dense-scattering media by transport-theory-based imaging operators and steady-state simulated data

We present a useful strategy for imaging perturbations of the macroscopic absorption cross section of dense-scattering media using steady-state light sources. A perturbation model based on transport theory is derived, and the inverse problem is simplified to a system of linear equations, WΔμ = ΔR, where W is the weight matrix, Δμ is a vector of the unknown perturbations, and ΔR is the vector of detector readings. Monte Carlo simulations compute the photon flux across the surfaces of phantoms containing simple or complex inhomogeneities. Calculation of the weight matrix is also based on the results of Monte Carlo simulations. Three reconstruction algorithms-conjugate gradient descent, projection onto convex sets, and the simultaneous algebraic reconstruction technique, with or without imposed positivity constraints-are used for image reconstruction. A rescaling technique that improves the conditioning of the weight matrix is also developed. Results show that the analysis of time-independent data by a perturbation model is capable of resolving the internal structure of a dense-scattering medium. Imposition of positivity constraints improves image quality at the cost of a reduced convergence rate. Use of the rescaling technique increases the initial rate of convergence, resulting in accurate images in a smaller number of iterations.

Boundary conditions for diffusion of light

In connection with recent work on remote imaging of random media by light, a straightforward generalization of the proper diffusion boundary conditions is presented that takes into account Fresnel reflection. The Milne problem at exterior boundaries is solved for various values of index of refraction, absorption, and scattering anisotropy parameters to yield extrapolated end points and extrapolation distances. A generalized interface condition is derived to replace the usual condition of continuity of intensity. Benchmark-quality numerical results are given for the extrapolation distance and for the new index-dependent parameter in the interface conditions. Difficulties in using the extrapolated end point when the index is sufficiently large are discussed, and a new image procedure suitable for this case is presented.

Mechanism of current-induced early afterdepolarizations in guinea pig ventricular myocytes

We investigated possible ionic mechanisms that cause early afterdepolarizations (EADs) following the injection of constant inward current in guinea pig ventricular myocytes by several interventions that affect failure of action potential repolarization. The amount of constant current was adjusted to measure the threshold potential (Vth) associated with the minimum inward current required for inducing EADs [threshold current (Ith)] and also the magnitude of EADs at Vth and following adjustment of current to generate takeoff potentials of -30 and -20 mV. Interventions associated with either inhibition of Ca2+ release from the sarcoplasmic reticulum (ryanodine 5 x 10(-6) M) or L-type membrane Ca2+ channel current (verapamil 1.1 x 10(-5) M and nisoldipine 5 x 10(-7) M) reduced or abolished EADs arising from -30 or -20 mV. Cells that generated delayed afterdepolarizations (DADs) in the absence of depolarizing current after 20 stimulations at 5 Hz either in control solution or following interventions associated with Ca2+ loading (reduced extracellular [K+] or increased extracellular [Ca2+]) also developed a marked shift in Vth of current-induced EADs at 1-Hz stimulation to more negative potentials [60.3 +/- 10.7 mV (mean +/- SD, n = 17) vs. -41.7 +/- 6.4 mV in cells without DADs in control solution (n = 25), P < 0.001]. Ca2+ loading also increased the magnitude of EADs arising from Vth and -20 mV. Exposure to quinidine (1.23 x 10(-5) M), which blocks both Na+ and delayed rectifier K+ channels, significantly reduced Ith but had only minimal effect on the magnitude of EADs. Our results suggest that L-type Ca2+ channel current and [Ca2+]-sensitive inward current associated with release of Ca2+ from the sarcoplasmic reticulum are the major currents that cause this form of EADs, and that Ca2+ loading promotes the development of large EADs likely to propagate to normal tissue.

Urban adolescent high-risk sexual behavior: corroboration of focus group discussions through pile-sorting. The AIDS Youth Research Team

Risk activities for acquisition of the human immunodeficiency virus (HIV) remain prevalent among urban adolescents. While interdisciplinary approaches to examine the variables contributing to risk/protective behaviors have been promoted, strategies for such explorations require further formulation. Recently we employed focus group discussions to explore factors placing urban adolescents at risk for engaging in HIV risk behaviors. The focus group format enables substantial interaction on a topic in a limited time period, but does not always provide expression of the full range of behavioral options. In this study we investigated the use of pile-sorts for confirmation of impressions from focus group discussions among 57 urban youths aged 10-14. The pile-sorts revealed some support for most of the views expressed in the group discussions. However, the sorts revealed more variability in views than was expressed in the group discussions. Substantial gender and age-based differences in perceptions were revealed with potentially important intervention implications.

Perceptions of vaccine efficacy, illness, and health among inner-city parents

A resurgence of measles in the past decade has focused attention on the limitations of current immunization programs, particularly for inner-city, low-income populations. As part of a larger study of immunization rates, we discussed perceptions of disease severity and vaccine efficacy, as well as the prioritization of the tasks of parenthood, with 40 parents of infants living in inner-city Baltimore to discover their beliefs about immunization. Vaccines were considered only partly successful; susceptibility to chickenpox after vaccination was repeatedly cited as evidence of vaccine failure. Fever was seen as a primary indicator of illness; thus, vaccines were believed to cause, rather than prevent, illness. Immunization was not considered a high-priority parental responsibility. These findings suggest future interventions be aimed at changing parental perceptions of vaccines as ineffective and of fever after immunization as an indicator of illness. Finally, immunizations should be made easily available, even during clinic visits for a child's illness.

Cardiac contractile proteins in hypertrophied and failing guinea pig heart

OBJECTIVE

The aim was to study changes in contractile proteins which accompany marked hypertrophy and heart failure in mammalian hearts initially containing predominantly V3 isomyosin.

METHODS

Left ventricular myosin and myofibrillar ATPase activity and right ventricular actomyosin ATPase activity were measured in normal guinea pig hearts, in hearts which were hypertrophied as a result of progressive left ventricular systolic overload following ascending aortic banding, and in hypertrophied hearts from animals which showed signs of overt congestive heart failure. Male guinea pigs weighing 225-275 g at the time of aortic banding were used for the studies.

RESULTS

Left ventricular myosin and myofibrillar ATPase activity and right ventricular actomyosin ATPase activity were correlated with body weight, left and right ventricular weight, and left ventricular peak systolic pressure during aortic occlusion. Left ventricular myosin ATPase activity and right ventricular actomyosin ATPase activity were markedly depressed in hypertrophied ventricles compared to control ventricles. Cardiac myofibrillar ATPase activity was lower in hypertrophied failing hearts than in control hearts over a wide range of calcium concentrations. In control animals and in those without heart failure, there was a nearly identical inverse relationship between left ventricular mass up to 1600 mg and myosin ATPase activity. Hypertrophied failing hearts were larger but showed little further reduction in cardiac myosin ATPase activity. Representative gel scans of non-dissociating pyrophosphate gels of left ventricular myosin from an 8 d postoperative aortic constricted animal and from its age and weight matched control showed predominantly V3 isomyosin with small amounts of V1 isoenzyme. However, preparations taken from guinea pigs 16 d after aortic constriction showed only the V3 isoform, whereas the V1 isoform was still apparent in control. Hypertrophied failing left ventricles developed less pressure per unit mass during brief aortic occlusion than non-failing left ventricles with comparable myosin ATPase activities.

CONCLUSIONS

These observations raise important questions as to the distribution of myosin isoforms in the normal adult guinea pig, and the possibility that myosin ATPase activity might be altered by post-translational modification. Although cardiac myosin ATPase activity correlates with left ventricular performance, it cannot fully explain the depressed performance of failing hearts in this model. Additional immunological studies of cardiac contractile proteins are required as well as studies designed to explore the implications of altered myosin ATPase activity for both contractile function and overall cellular homeostasis.

Voluntary hyperventilation in obesity hypoventilation

Arterial blood gas analysis was performed before and after 60 to 90 s of voluntary hyperventilation in 27 consecutive patients with occlusive sleep apnea syndrome (OSA) and daytime hypercapnia. The percentage of fall in PaCO2 from baseline was examined in relationship to age, body mass index, sleep-disordered breathing indices, and pulmonary function variables. In 14 subjects without airflow obstruction, only one individual could not voluntarily hyperventilate into the normal range, whereas 6 of 13 subjects with airflow obstruction could not hyperventilate to eucapnia. The average percentage of fall in PaCO2 was 16 mm Hg (SEM = 1.3 mm Hg). The percentage of fall in PaCO2 correlated significantly with FEV1/FVC ratio (r = 0.47, p = 0.01) and with FEV1 (r = 0.5, p = 0.008). Although the baseline PaCO2 did not correlate with FEV1, the posthyperventilation PaCO2 did (r = 0.54, p = 0.003). Voluntary hyperventilation studies herein suggest a predominant role for impairment of ventilatory control in the maintenance of hypercapnia in OSA since a fall of PaCO2 into the normal range can usually be obtained. The correlation between the percentage of fall in PaCO2 and spirometric measures of respiratory mechanics, as well as the inability of some subjects to normalize the PaCO2 voluntarily suggests an added role for respiratory mechanical impairment in obesity hypoventilation.

Growth in children with congenital hypothyroidism detected by neonatal screening

A prospective analysis of physical growth in 56 children with congenital hypothyroidism compared the children's height, weight, and head circumference with population percentiles. Two measures of skeletal maturation and predictions of adult height were also compared with population standards. The mean percentiles for the children's height and head circumference were higher than population means. Although mean bone age scores were slightly higher, predictions of adult height did not differ significantly from midparental height (arithmetic mean of sum of parental heights) and population means. The duration of intrauterine hypothyroidism as measured by gestational bone age and the duration of postnatal hypothyroidism were inversely correlated with heights attained up to 9 years. This association suggests a possible long-term influence of early hypothyroidism on growth. In children with congenital hypothyroidism, maintenance of serum thyroxine levels in the upper half of the normal range results in normal growth patterns.

Compensatory hypertrophy and failure in gradual pressure-overloaded guinea pig heart

Left ventricular hypertrophy has been produced in the guinea pig by a procedure that gradually increases left ventricular afterload. A mildly constricting band was placed around the ascending aortas of very young guinea pigs (225-275 g). With growth to 500-1,000 g, left ventricular systolic pressure increased and left ventricular hypertrophy developed. In approximately 50% of these animals, the hypertrophy was associated with normal left ventricular function and with no unusual symptoms or evidence of heart failure. The other animals developed dyspnea, which appeared an average of 41 days after banding. Dyspneic animals had normal body weight, markedly increased right ventricular and lung weights, decreased left ventricular norepinephrine content, diminished maximum left ventricular pressure generating capacity, and a significantly higher incidence of left ventricular interstitial and perivascular fibrosis. These findings demonstrate that even when left ventricular overload is imposed gradually by banding the aortas of young animals, myocardial decompensation ultimately ensues in a significant proportion of such animals. The slow imposition of loading, the slow rate of decompensation, and the ability to identify animals in heart failure by clinical dyspnea make this model uniquely valuable for studies on the mechanisms of heart failure.

Breath-by-breath interactions between inspiratory and expiratory duration in occlusive sleep apnea

We examined interactions between inspiratory duration (TI), expiratory duration (TE), and inspiratory (esophageal) pressure (Pes) generation in seven subjects with confirmed occlusive sleep apnea. Breath-by-breath values of TI, TE, and Pes were identified by digital computer during 21 260-s epochs of repetitive occlusive apnea during non-rapid-eye-movement sleep. The control theory of interacting nonlinear oscillators was used to categorize the interaction between TI and TE for each epoch as either 1) synchronization, the strongest possible interaction between biological oscillators; 2) relative entrainment, a moderate interaction between oscillators; or 3) relative coordination, a weak interaction. The latter two interactions were characterized by systemic oscillations in the moving cross-correlation between TI and TE. The relationship between TI and Pes was analyzed in a similar fashion. Significant oscillations were present in all three parameters (P less than 0.0001 for each). We observed significant negative correlations between TI and TE and between TI and Pes (P less than 0.001 for each) when all breaths for all epochs were pooled. In no epoch was there a significant positive correlation between TI and TE or Pes. All three interactions were observed between TI and TE: five epochs of synchronization, nine of relative entrainment, and seven of relative coordination. In contrast, 19 of 21 epochs exhibited synchronization between TI and Pes, with 2 epochs of relative entrainment. The relative frequency of TI vs. Pes synchronization was significantly greater than TI vs. TE synchronization (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Isorhythmic Dissociation--a "physiological" arrhythmia

The behavior of the sino-atrial mechanism in isorhythmic dissociation (IRD) was studied in 21 patients, nine with spontaneous IRD and 12 with artificially pacemaker-induced IRD following electrode placement for heart block. Successive P-P, R-R and P-R intervals and blood pressure (BP) fluctuations were determined and graphically interrelated at control and during IRD. Several features were observed: a. IRD was present only when the independent ventricular rate was close to the atrial; b. P rate oscillations closely followed the P-R interval-dependent BP fluctuations (mean difference 30 mmHg) during IRD. In cardiogenic shock and in severe hypertension IRD could not be achieved easily; c. While during complete dissociation or during 1:1 A-V conduction the sinus rate was remarkably constant (2-4 beats/min variations), it showed marked oscillations (differences of 6-19, mean 13, beats/min) during IRD. All the data and calculations support the theory that in most instances of IRD, the arrhythmia is sustained by the normal physiologically active baroreceptor reflex arc.