Replacement therapy with a monoclonal antibody purified protein C concentrate in newborns with severe congenital protein C deficiency

Protein C replacement therapy with a monoclonal antibody purified, virus inactivated protein C concentrate was carried out in nine infants (three male, six female) with severe congenital protein C deficiency and life-threatening purpura fulminans and/or thrombosis associated with disseminated intravascular coagulation (DIC). Eight infants were homozygous for protein C deficiency; one was a compound heterozygote. The treatment period varied from 22 days to three years. The half-life of protein C was found to be as short as two to three hours during activation of the coagulation system, increasing to approximately ten hours after stabilization. During the acute phase, protein C levels of 0.10 to 0.25 IU/mL were associated with elevated markers of coagulation activation indicating DIC, while protein C levels greater than 0.25 were associated with normalization of coagulation markers. No product-related side effects were reported. Episodes of bleeding or purpura recurred in all patients who were switched to oral anticoagulant therapy, necessitating reinstatement of protein C replacement therapy, either as needed to control symptoms, or on a long-term prophylactic schedule, alone or in addition to oral anticoagulation. Home treatment with protein C concentrate allowed a near-normal life-style for patients who otherwise would be hospitalized for long periods of time.

Activation of prefrontal cortex in children during a nonspatial working memory task with functional MRI

Functional magnetic resonance imaging (fMRI) was used to examine the pattern of activity of prefrontal cortex in prepubertal children during performance of a nonspatial working memory task. The children observed sequences of letters and responded whenever a letter repeated with exactly one nonidentical letter intervening. In a comparison task, subjects monitored similar sequences of letters for any occurrence of a single, prespecified target letter. Location of activation closely approximated that observed in a recent fMRI study with adults using exactly the same task. Activation of the inferior and middle frontal gyri was reliably observed within individual subjects during performance of the working memory task relative to the comparison task. Activation increased and decreased with a time course that was highly consistent with the task manipulations and correlated with behavioral performance. To our knowledge, this study is one of the first to demonstrate the applicability of fMRI to a normative developmental population. Issues of age dependence of the hemodynamic responses of fMRI are discussed.

An anatomically constrained neural network model of fear conditioning

Conditioning of fear reactions to an auditory conditioned stimulus (CS) paired with a footshock unconditioned stimulus (US) involves CS transmission to the amygdala from the auditory thalamus, the auditory cortex, or both. This article presents a simple neural network model of this neural system. The model consists of modules of mutually inhibitory nonlinear units representing the different relevant anatomical structures of the thalamo-amygdala and thalamo-corticoamygdala circuitry. Frequency-specific changes produced by fear conditioning were studied at the behavioral level (stimulus generalization) and the single-unit level (receptive fields). The findings mirror effects observed in conditioning studies of animals. This computational model provides an initial grounding for explorations of how emotional information and behavior are related to anatomical and physiological observations.

Improved assessment of significant activation in functional magnetic resonance imaging (fMRI): use of a cluster-size threshold

The typical functional magnetic resonance (fMRI) study presents a formidable problem of multiple statistical comparisons (i.e., > 10,000 in a 128 x 128 image). To protect against false positives, investigators have typically relied on decreasing the per pixel false positive probability. This approach incurs an inevitable loss of power to detect statistically significant activity. An alternative approach, which relies on the assumption that areas of true neural activity will tend to stimulate signal changes over contiguous pixels, is presented. If one knows the probability distribution of such cluster sizes as a function of per pixel false positive probability, one can use cluster-size thresholds independently to reject false positives. Both Monte Carlo simulations and fMRI studies of human subjects have been used to verify that this approach can improve statistical power by as much as fivefold over techniques that rely solely on adjusting per pixel false positive probabilities.

An anatomically constrained neural network model of fear conditioning

Conditioning of fear reactions to an auditory conditioned stimulus (CS) paired with a footshock unconditioned stimulus (US) involves CS transmission to the amygdala from the auditory thalamus, the auditory cortex, or both. This article presents a simple neural network model of this neural system. The model consists of modules of mutually inhibitory nonlinear units representing the different relevant anatomical structures of the thalamo-amygdala and thalamo-corticoamygdala circuitry. Frequency-specific changes produced by fear conditioning were studied at the behavioral level (stimulus generalization) and the single-unit level (receptive fields). The findings mirror effects observed in conditioning studies of animals. This computational model provides an initial grounding for explorations of how emotional information and behavior are related to anatomical and physiological observations.

Lack of blood pressure effect with calcium and magnesium supplementation in adults with high-normal blood pressure. Results from Phase I of the Trials of Hypertension Prevention (TOHP). Trials of Hypertension Prevention (TOHP) Collaborative Research Group

Phase I of the Trials of Hypertension Prevention (TOHP) was a randomized, multicenter investigation that included double-blind, placebo-controlled testing of calcium and magnesium supplementation among 698 healthy adults (10.5% blacks and 31% women) aged 30 to 54 years with high-normal diastolic blood pressure (DBP) (80 to 89 mm Hg). Very high compliance (94 to 96% by pill counts) with daily doses of 1 g of calcium (carbonate), 360 mg of magnesium (diglycine), or placebos was corroborated for the active supplements by significant net increases in all urine and serum compliance measures in white men and for urine compliance measures in white women. Overall, neither calcium nor magnesium produced significant changes in blood pressure at 3 and 6 months. Analyses stratified by baseline intakes of calcium, magnesium, sodium, or initial blood pressures also showed no effect of supplementation. These analyses suggested that calcium supplementation may have resulted in a DBP decrease in white women and that response modifiers in this subgroup might have included lower initial urinary calcium levels, urinary sodium levels, or lower body mass index. However, overall analyses indicated that calcium and magnesium supplements are unlikely to lower blood pressure in adults with high-normal DBP. The subgroup analyses, useful to formulate hypotheses, raise the possibility of a benefit to white women, which requires testing in future trials.

Design of a multicenter trial to evaluate long-term life-style intervention in adults with high-normal blood pressure levels. Trials of Hypertension Prevention (phase II). Trials of Hypertension Prevention (TOHP) Collaborative Research Group

Phase II of the Trials of Hypertension Prevention (TOHP) is a multicenter, randomized trial sponsored by the National Heart, Lung, and Blood Institute designed to test whether weight loss alone, sodium reduction alone, or the combination of weight loss and sodium reduction will decrease diastolic (DBP) and systolic blood pressure (SBP) as well as the incidence of hypertension (DBP > or = 90 mm Hg, SBP > or = 140 mm Hg, and/or use of antihypertensive medications) in subjects with high-normal DBP (83 to 89 mm Hg) and SBP less than 140 mm Hg at entry. These interventions were chosen for longer-term testing with end points including hypertension prevention as well as blood pressure (BP) change based on their demonstrated short-term efficacy in reducing BP in phase I of TOHP. The phase II study population is comprised of 2382 participants (1566 men and 816 women) who are 110 to 165% of desirable body weight, allocated at random to the four treatment arms using a 2 x 2 factorial design. The trial has 80% power to detect an overall treatment effect on DBP of 1.2 mm Hg for weight loss or sodium reduction and a difference of 1.6 mm Hg between the combined intervention and placebo groups. BP observers are blinded to participant treatment assignments. Participants will be followed for 3 to 4 years. This trial may have important public policy implications concerning the ability of life-style modifications to reduce BP and prevent the development of hypertension over the long term, thereby avoiding the need for drug therapy which while effective is costly and may have side effects.

Baseline characteristics of participants in phase II of the Trials of Hypertension Prevention (TOHP II). Trials of Hypertension Prevention (TOHP) Collaborative Research Group

Phase II of the Trials of Hypertension Prevention (TOHP II) is a multicenter, controlled clinical trial designed to test whether weight loss, a reduced sodium intake, or a combination of weight loss and a reduced sodium intake will lower blood pressure (BP) and prevent the occurrence of hypertension. The study population consists of middle-aged, moderately overweight individuals with a diastolic BP between 83 and 89 mm Hg. Of the 2382 randomized participants, 816 (34%) are female and 494 (21%) are from a racial or ethnic minority background. At baseline, mean dietary intakes of sodium, based on measurements of 24-hour urinary excretion, were 199 mmol/d in men and 154 mmol/d in women. The average body mass index was 30.9 kg/m2. Across the four randomized groups, there was no substantial imbalance in the distribution of baseline variables; however, the mean age in the four groups was slightly but significantly different (range: 43.2 to 44.2 years, P = 0.02). A comparison of baseline characteristics of TOHP II participants with those of participants in three other primary prevention trials reveals a high level of mean dietary sodium intake in each study. Data reported in this article indicate that any subsequent differences in BP among the randomized groups are unlikely to result from maldistribution of known confounding variables at baseline. Finally, because of the high prevalence of overweight and excessive sodium intake in the United States, results from TOHP II should be broadly applicable to the general population.

The effect of potassium supplementation in persons with a high-normal blood pressure. Results from phase I of the Trials of Hypertension Prevention (TOHP). Trials of Hypertension Prevention (TOHP) Collaborative Research Group

We conducted a randomized, double-blind, placebo-controlled trial of oral potassium chloride supplementation (60 mmol/d) in 353 men and women with an initial average diastolic blood pressure between 80 and 89 mm Hg. In the active (n = 178) compared to the placebo (n = 175) treatment group, the urinary potassium level was significantly (p < 0.001) increased by an average of 44.0 and 42.3 mmol/24 h following 3 and 6 months of therapy, respectively. Compared to placebo, active treatment was associated with a small (mean = 1.8 mm Hg) but significant (p = 0.04) reduction in diastolic blood pressure following 3 months of therapy. Following 6 months, however, this apparent treatment effect had virtually disappeared (mean reduction in diastolic blood pressure = 0.3 mm Hg). There was no significant effect of potassium supplementation on systolic blood pressure at either follow-up visit. There was a significant, independent, dose-response relationship between change in both 24-hour urinary potassium excretion and urinary sodium-potassium ratio and the corresponding change in diastolic blood pressure (-1.49 mm Hg for the highest versus the lowest quartile of change in urinary potassium excretion.

Cytotoxic interactions of tumor necrosis factor, melphalan and 41.8 degrees C hyperthermia

Experience with limb perfusion-hyperthermia, TNF, and L-PAM suggests dramatic clinical responses in sarcoma and malignant melanoma. To extrapolate these results to clinical 41.8 degrees C whole-body hyperthermia (WBH) and systemic therapy, we studied the cytotoxic interactions of TNF, L-PAM and hyperthermia in L929 cells. The optimal sequence was TNF preceding 41.8 degrees C hyperthermia by 48 h, and L-PAM given simultaneously with heat. Trimodality synergism between TNF, hyperthermia and L-PAM was demonstrated. Non-cytotoxic doses of TNF had a super-additive interaction with L-PAM/heat. Conversely, non-cytotoxic doses of L-PAM had super-additive interactions with TNF followed by hyperthermia. Relative to therapeutic index, we studied WBH, L-PAM and TNF in non-tumor bearing mice. The optimal trimodality sequence did not result in increased normal tissue toxicity compared to L-PAM alone. The concentrations and sequencing of TNF and L-PAM studied are consistent with clinical application to WBH.

Spiral K-space MR imaging of cortical activation

Brain function can be mapped with magnetic resonance (MR) imaging sensitized to regional changes in blood oxygenation due to cortical activation. Several MR imaging methods, including conventional imaging and echo-planar imaging, have been successfully used for this purpose. The authors investigated spiral k-space MR imaging, implemented with an unmodified 1.5-T clinical imager, for imaging of cortical activation. A gradient-echo, spiral k-space imaging method was used to measure activation in the primary visual cortex (number sequence task), primary motor cortex (fist-clenching task), and prefrontal cortex (verbal fluency task). Comparison of conventional and spiral k-space imaging in the visual and motor cortex, in which signal-to-noise ratio, voxel size, and imaging time were matched, showed that artifacts were reduced with the spiral k-space method, while the area and degree of activation were similar. The number of sections that could be imaged in a fixed time interval was increased by a factor of four with this implementation of spiral k-space imaging compared with conventional imaging.

A new technological approach to radiant heat whole body hyperthermia

A new methodology for administering radiant heat whole body hyperthermia (WBH) in humans is described. The technology utilized circulates hot water in a cylinder constructed from copper tubing; the design incorporates a counter current distribution system to maintain thermal constancy. The tubing is coated with a temperature resistant high emissivity finish. Other features include a humidification system to eliminate evaporative heat losses. Data accrued from initial evaluation of this apparatus with a canine model shows that there was no detectable WBH-related hematological, biochemical or physiological toxicity. The perceived advantages of this WBH-system are discussed.

Short report: the effect of fish oil on blood pressure and high-density lipoprotein-cholesterol levels in phase I of the Trials of Hypertension Prevention

OBJECTIVE

To study the effects of moderate doses of fish oil on blood pressure and high-density lipoprotein (HDL)-cholesterol.

METHODS

The participants were 350 normotensive men and women aged 30-54 years who were enrolled from seven academic medical centers in phase I of the Trials of Hypertension Prevention. They were randomly assigned to receive placebo or 6 g purified fish oil once a day, which supplied 3 g n-3 polyunsaturated fatty acids for 6 months.

RESULTS

Baseline blood pressure was (mean +/- SD) 123 +/- 9/81 +/- 5 mmHg. The mean differences in the blood pressure changes between the fish oil and placebo groups were not statistically significant. There was no tendency for fish oil to reduce blood pressure more in subjects with baseline blood pressure in the upper versus the lower quartile (132/87 versus 114/75 mmHg), low habitual fish consumption (0.4 versus 2.9 times a week) or low baseline plasma levels of n-3 fatty acids. Fish oil increased HDL2-cholesterol significantly compared with the placebo group. Subgroup analysis showed this effect to be significant in the women but not in the men. Increases in serum phospholipid n-3 fatty acids were significantly correlated with increases in HDL2-cholesterol and decreases in systolic blood pressure.

CONCLUSION

Moderate amounts of fish oil (6 g/day) are unlikely to lower blood pressure in normotensive persons, but may increase HDL2-cholesterol, particularly in women.

Mortality following ventricular arrhythmia suppression by encainide, flecainide, and moricizine after myocardial infarction. The original design concept of the Cardiac Arrhythmia Suppression Trial (CAST)

OBJECTIVE

To test the hypothesis that in survivors of myocardial infarction, the suppression of ventricular premature depolarizations improves survival free of cardiac arrest and arrhythmic death.

DESIGN

International, prospective, multicenter, randomized, placebo-controlled trial.

SETTING

University and community hospitals.

PATIENTS

A total of 3549 patients with myocardial infarction and left ventricular dysfunction.

INTERVENTION

Administration of encainide, flecainide, moricizine, or placebo to suppress ventricular premature depolarizations.

MAIN OUTCOME MEASURES

Overall survival and survival free of cardiac arrest or arrhythmic death were compared in patients randomized to long-term, active antiarrhythmic drug therapy vs corresponding placebo, using the stratified log rank statistic.

RESULTS

At 1 year from the time of randomization to blinded therapy, 95% of placebo-treated patients vs 90% of active drug-treated patients remained alive (P = .0006). Similarly, at 1 year, 96% of placebo-treated patients vs 93% of active drug-treated patients remained free of cardiac arrest or arrhythmic death (P = .003).

CONCLUSIONS

The suppression of asymptomatic or mildly symptomatic ventricular arrhythmias after myocardial infarction does not improve survival and can increase mortality. Treatment strategies designed solely to suppress these arrhythmias should no longer be followed.

Arabidopsis thaliana auxotrophs reveal a tryptophan-independent biosynthetic pathway for indole-3-acetic acid

We used tryptophan auxotrophs of the dicot Arabidopsis thaliana (wall cress) to determine whether tryptophan has the capacity to serve as a precursor to the auxin, indole-3-acetic acid (IAA). Quantitative gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS) revealed that the trp2-1 mutant, which is defective in the conversion of indole to tryptophan, accumulated amide- and ester-linked IAA at levels 38-fold and 19-fold, respectively, above those of the wild type. Tryptophan and free IAA were isolated from the trp2-1 mutant grown in the presence of [15N]anthranilate and [2H5]tryptophan, and the relative 15N and 2H5 enrichments of tryptophan and IAA were determined via GC-SIM-MS. The 15N enrichment of tryptophan, 13% +/- 4%, was less than the 15N enrichment of the IAA pool, 39% +/- 4%; therefore, IAA biosynthesis occurs via a tryptophan-independent pathway. The amount of 2H5 incorporated by the plant into IAA from tryptophan (9% +/- 4%) was low and only slightly above the level of spontaneous, nonenzymatic conversion of [2H5]tryptophan to [2H5]IAA. These results show that the dicot Arabidopsis is similar to the monocot Zea mays in that the major route of IAA biosynthesis does not occur through tryptophan.

Functional topographic mapping of the cortical ribbon in human vision with conventional MRI scanners

The human brain has anatomically distinct areas in which processing is laid out in space at the millimetre level with substantial variation across individuals. Activity occurs along a cortical ribbon 1.5-3 mm thick in response to specific stimuli. Here we report the first use of cortical ribbon analysis on humans using non-invasive functional magnetic resonance imaging techniques performed with a conventional 1.5 T MRI scanner. Changes in activation were detected using T2*-weighted, gradient echo imaging sequences. Subjects observed partial field, flashing checkerboard patterns (left-right, top-bottom, half rings, and wedges). Stimuli produced magnetic resonance signal changes in the 1-8% range, varying at the millimetre scale, which showed contralateral vertically reflected patterns of activation in the visual cortex. To compare the spatial topographies across subjects, computer algorithms were used to control for the subject-unique folding of cortex, providing a flattened cortical ribbon identifying four topographically distinct areas.

Phase I clinical trial of carboplatin and 41.8 degrees C whole-body hyperthermia in cancer patients

PURPOSE

To evaluate the biologic interactions and toxicities of carboplatin combined with 41.8 degrees C whole-body hyperthermia (WBH) for 60 minutes in a phase I clinical trial.

PATIENTS AND METHODS

Thirty assessable patients with cancer refractory to conventional therapy were treated. During induction therapy, patients received WBH alone in week 1, WBH plus carboplatin in week 2, and carboplatin alone in week 5. Carboplatin dose was escalated (three patients per group) as follows: 100, 150, 200, 250, 300, 350, 400, 480, and 575 mg/m2; three additional patients were entered at 480 mg/m2. Carboplatin was administered at target temperature.

RESULTS

Comparisons of the mean/median WBC and platelet nadirs for carboplatin alone and carboplatin plus WBH demonstrated no enhancing effect by WBH. Toxicities including nausea and/or vomiting, as well as myelosuppression, were within acceptable limits, allowing for escalation to a dose of 575 mg/m2; three of three patients at this dose level experienced grade 4 myelosuppression with no associated infection or bleeding. No renal toxicity was observed. Analysis of platinum in plasma ultrafiltrate and urine showed only slight effects of WBH on the pharmacokinetics and renal excretion of platinum. Responses included the following: lung--minor response (200 mg/m2); gastrointestinal neuroendocrine--complete response (CR) (400 mg/m2); pancreatic--partial response (PR) (480 mg/m2); small bowel--PR (575 mg/m2); ovarian--CR, two patients (575 mg/m2), with marker data suggesting WBH enhancement of carboplatin cytotoxicity. Another three patients experienced clinical improvement after WBH plus carboplatin, but progression with carboplatin alone (lung, 400 mg/m2; gastrointestinal neuroendocrine, 480 mg/m2; melanoma, 480 mg/m2).

CONCLUSION

We conclude that carboplatin with WBH is well tolerated even at conventional carboplatin doses. Clinical results are consistent with preclinical predictions of an increased therapeutic index for this combination, which encourages future clinical studies.

Hypertension in the elderly: age- and disease-related complications and therapeutic implications

Effective treatment of hypertension in the elderly requires an understanding of both the progressive course of the disease and the impact of aging on the cardiovascular system, including physiological, genetic, lifestyle, and environmental factors. Review of the literature that has attempted to define the impact of an "aging process" on cardiovascular structure and function reveals a diversity of findings and interpretations. However, in general, normotensive elderly subjects exhibit the heart and vascular characteristics of "muted" hypertension, including many features of younger hypertensive patients: cardiac hypertrophy, diminution in resting left ventricular early diastolic filling rate, increased arterial stiffness and aortic impedance, diminution in the baroreceptor reflex, a diminished response to catecholamines and diminished renal blood flow, and an increase in peripheral vascular resistance (PVR). Treatment of elderly hypertensives is more challenging because of the greater likelihood of the presence of concomitant diseases, most importantly, coronary and peripheral atherosclerosis, renal dysfunction, and diabetes mellitus. Isolated systolic hypertension (ISH), the most common form of hypertension in the elderly, has also been clearly shown to be an important predictor of cardiovascular morbidity and mortality, including coronary artery disease, congestive heart failure, and stroke. Treatment of ISH has been shown to lower systolic pressure safely and effectively in the elderly. By reducing PVR, and possibly the arterial stiffness, and thus the early reflected pulse waves, vasodilators, including calcium antagonists, may lower these three components of arterial impedance, and hence lower the arterial load on the heart. The cardiac hypertrophy and reduced left ventricular filling rate associated with hypertension in older individuals can also be ameliorated, to some extent, by calcium channel blockers.