Erythrocytic pyruvate kinase mutations causing hemolytic anemia, osteosclerosis, and secondary hemochromatosis in dogs

BACKGROUND

Erythrocytic pyruvate kinase (PK) deficiency, first documented in Basenjis, is the most common inherited erythroenzymopathy in dogs.

OBJECTIVES

To report 3 new breed-specific PK-LR gene mutations and a retrospective survey of PK mutations in as mall and selected group of Beagles and West Highland White Terriers (WHWT).

ANIMALS

Labrador Retrievers (2 siblings, 5 unrelated), Pugs (2 siblings, 1 unrelated), Beagles (39 anemic, 29 other),WHWTs (22 anemic, 226 nonanemic), Cairn Terrier (n = 1).

METHODS

Exons of the PK-LR gene were sequenced from genomic DNA of young dogs (<2 years) with persistent highly regenerative hemolytic anemia.

RESULTS

A nonsense mutation (c.799C>T) resulting in a premature stop codon was identified in anemic Labrador Retriever siblings that had osteosclerosis, high serum ferritin concentrations, and severe hepatic secondary hemochromatosis. Anemic Pug and Beagle revealed 2 different missense mutations (c.848T>C, c.994G>A, respectively) resulting in intolerable amino acid changes to protein structure and enzyme function. Breed-specific mutation tests were developed. Among the biased group of 248 WHWTs, 9% and 35% were homozygous (affected) and heterozygous, respectively, for the previously described mutation (mutant allele frequency 0.26). A PK-deficient Cairn Terrier had the same insertion mutation as the affected WHWTs. Of the selected group of 68 Beagles, 35% were PK-deficient and 3% were carriers (0.37).

CONCLUSIONS AND CLINICAL IMPORTANCE

Erythrocytic PK deficiency is caused by different mutations in different dog breeds and causes chronic severe hemolytic anemia, hemosiderosis, and secondary hemochromatosis because of chronic hemolysis and, an as yet unexplained osteosclerosis. The newly developed breed-specific mutation assays simplify the diagnosis of PK deficiency.

Missense mutation in PFKM associated with muscle-type phosphofructokinase deficiency in the Wachtelhund dog

Hereditary muscle-type phosphofructokinase (PFK) deficiency causing intermittent hemolytic anemia and exertional myopathy due to a single nonsense mutation in PFKM has been previously described in English Springer and American Cocker Spaniels, Whippets, and mixed breed dogs. We report here on a new missense mutation associated with PFK deficiency in Wachtelhunds. Coding regions of the PFKM gene were amplified from genomic DNA and/or cDNA reverse-transcribed from RNA of EDTA blood of PFK-deficient and clinically healthy Wachtelhunds and control dogs. The amplicons were sequenced and compared to the published canine PFKM sequence. A point mutation (c.550C>T, in the coding sequence of PFKM expressed in blood) was found in all 4 affected Wachtelhunds. This missense mutation results in an amino acid substitution of arginine (Arg) to tryptophan (Trp) at position 184 of the protein expressed in blood (p.Arg184Trp). The mutation is located within an alpha-helix, and based on the SIFT analysis, this amino acid substitution is not tolerated. Amplifying the region around this mutation and digesting the PCR fragment with the restriction enzyme MspI, produces fragments that readily differentiate between PFK-deficient, carrier, and normal animals. Furthermore, we document 2 additional upstream PFKM exons expressed in canine testis but not in blood. Despite their similar phenotypic appearance and use for hunting, Wachtelhunds and English Springer Spaniels are not thought to have common ancestors. Thus, it is not surprising that different mutations are responsible for PFK deficiency in these breeds. Knowledge of the molecular basis of PFK deficiency in Wachtelhunds provides an opportunity to screen and control the spread of this deleterious trait.

Novel measurements of periaortic adipose tissue in comparison to anthropometric measures of obesity, and abdominal adipose tissue

BACKGROUND

Perivascular adipose tissue may be associated with the amount of local atherosclerosis. We developed a novel and reproducible method to standardize volumetric quantification of periaortic adipose tissue by computed tomography (CT) and determined the association with anthropometric measures of obesity, and abdominal adipose tissue.

METHODS

Measurements of adipose tissue were performed in a random subset of participants from the Framingham Heart Study (n=100) who underwent multidetector CT of the thorax (ECG triggering, 2.5 mm slice thickness) and the abdomen (helical CT acquisition, 2.5 mm slice thickness). Abdominal periaortic adipose tissue (AAT) was defined by a 5 mm cylindrical region of interest around the aortic wall; thoracic periaortic adipose tissue (TAT) was defined by anatomic landmarks. TAT and AAT were defined as any voxel between -195 and -45 HU and volumes were measured using dedicated semiautomatic software. Measurement reproducibility and association with anthropometric measures of obesity, and abdominal adipose tissue were determined.

RESULTS

The intra- and inter-observer reproducibility for both AAT and TAT was excellent (ICC: 0.97 and 0.97; 0.99 and 0.98, respectively). Similarly, the relative intra- and inter-observer difference was small for both AAT (-1.85+/-1.28% and 7.85+/-6.08%; respectively) and TAT (3.56+/-0.83% and -4.56+/-0.85%, respectively). Both AAT and TAT were highly correlated with visceral abdominal fat (r=0.65 and 0.77, P<0.0001 for both) and moderately correlated with subcutaneous abdominal fat (r=0.39 and 0.42, P<0.0001 and P=0.009), waist circumference (r=0.49 and 0.57, P<0.0001 for both) and body mass index (r=0.47 and 0.58, P<0.0001 for both).

CONCLUSION

Standardized semiautomatic CT-based volumetric quantification of periaortic adipose tissue is feasible and highly reproducible. Further investigation is warranted regarding associations of periaortic adipose tissue with other body fat deposits, cardiovascular risk factors and clinical outcomes.

14C Activity and Global Carbon Cycle Changes over the Past 50,000 Years

A series of 14C measurements in Ocean Drilling Program cores from the tropical Cariaco Basin, which have been correlated to the annual-layer counted chronology for the Greenland Ice Sheet Project 2 (GISP2) ice core, provides a high-resolution calibration of the radiocarbon time scale back to 50,000 years before the present. Independent radiometric dating of events correlated to GISP2 suggests that the calibration is accurate. Reconstructed 14C activities varied substantially during the last glacial period, including sharp peaks synchronous with the Laschamp and Mono Lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments. Simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14C production rate together with plausible changes in deep-ocean ventilation and the global carbon cycle during glaciation.

Patient evaluation of the hotel function of hospitals

BACKGROUND

A means of measuring patient satisfaction is essential in the effort to improve the quality of health care delivered in our nation's hospitals. Accurate feedback allows employers to better meet patients' needs and allows hospital administrators to improve service delivery. Patients are empowered by having a voice in the manner in which their health care is delivered. Moreover, improving the efficiency of the health care delivery system decreases health care costs. Hospital comparisons can be made readily available to a large audience through the Internet, resulting in empowerment of the patient and a universal improvement in hospital care. This is the first multi-institutional analysis of patient satisfaction among New York City and northern New Jersey area tertiary care hospitals. In this study, we evaluated the patient-assessed hotel function of hospitals in a single geographic region to determine whether clinically and statistically significant differences would be revealed that could provide beneficial information to stakeholders in the healthcare system.

METHODS

Patients (n = 261) who had spent a night during the past year in one of eleven hospitals within 60 miles of New York City were chosen at random from doctors' waiting rooms. On average, 24 patients from each hospital were surveyed. They were asked to complete a questionnaire that rated the various departments in the hospital on qualities such as courtesy, promptness, and cleanliness. The questionnaire also rated important characteristics of the patient experience, such as the ease of parking and the taste of the food. Each item on the survey was coded on a scale of 1 to 10 with 10 being the most positive response. The 26 specific questions were divided into 14 domains. Averages in each domain were compared by gender, age, and hospital identity, attractiveness, and setting. All statistical calculations were performed using SPSS/PC, and means were compared using t-tests.

RESULTS

Analysis designed to evaluate outcomes between each of the possible 54 pairs of hospitals comparisons revealed statistically significant differences as often as 44% of the time in some outcomes measures (logistics), but as rarely as 7% of the time in others (billing function). Clinically significant differences (>2 units per scale) were frequently evident, although the ranges differed dramatically depending on the domains surveyed. Although age, gender, and race/ethnicity were generally not predictive of satisfaction, non-urban setting was correlated with greater patient satisfaction.

CONCLUSION

By having access to patient satisfaction comparisons among hospitals, patients are empowered to make better choices, employers can identify and adapt to patient preferences, and administrators can improve the services delivered and decrease health care costs by improving efficiency. Although our study was somewhat limited by patient selection biases, the study's results suggest that Internet-based tools of comparison will enable patients to make free and informed decisions about their health care by comparing local hospitals and voting on their impressions of the facilities from which they receive care.

Glacial surface temperatures of the southeast Atlantic Ocean

A detailed record of sea surface temperature from sediments of the Cape Basin in the subtropical South Atlantic indicates a previously undocumented progression of marine climate change between 41 and 18 thousand years before the present (ky B.P.), during the last glacial period. Whereas marine records typically indicate a long-term cooling into the Last Glacial Maximum (around 21 ky B.P.) consistent with gradually increasing global ice volume, the Cape Basin record documents an interval of substantial temperate ocean warming from 41 to 25 ky B.P. The pattern is similar to that expected in response to changes in insolation owing to variations in Earth's tilt.

Ischemia causes muscle fatigue

The purpose of this investigation was to determine whether ischemia, which reduces oxygenation in the extensor carpi radialis (ECR) muscle, causes a reduction in muscle force production. In eight subjects, muscle oxygenation (TO2) of the right ECR was measured noninvasively and continuously using near infrared spectroscopy (NIRS) while muscle twitch force was elicited by transcutaneous electrical stimulation (1 Hz, 0.1 ms). Baseline measurements of blood volume, muscle oxygenation and twitch force were recorded continuously, then a tourniquet on the upper arm was inflated to one of five different pressure levels: 20, 40, 60 mm Hg (randomized order) and diastolic (69 +/- 9.8 mm Hg) and systolic (106 +/- 12.8 mm Hg) blood pressures. Each pressure level was maintained for 3-5 min, and was followed by a recovery period sufficient to allow measurements to return to baseline. For each respective tourniquet pressure level, mean TO2 decreased from resting baseline (100% TO2) to 99 +/- 1.2% (SEM), 96 +/- 1.9%, 93 +/- 2.8%, 90 +/- 2.5%, and 86 +/- 2.7%, and mean twitch force decreased from resting baseline (100% force) to 99 +/- 0.7% (SEM), 96 +/- 2.7%, 93 +/- 3.1%, 88 +/- 3.2%, and 86 +/- 2.6%. Muscle oxygenation and twitch force at 60 mm Hg tourniquet compression and above were significantly lower (P < 0.05) than baseline value. Reduced twitch force was correlated in a dose-dependent manner with reduced muscle oxygenation (r = 0.78, P < 0.001). Although the correlation does not prove causation, the results indicate that ischemia leading to a 7% or greater reduction in muscle oxygenation causes decreased muscle force production in the forearm extensor muscle. Thus, ischemia associated with a modest decline in TO2 causes muscle fatigue.

Synchronous radiocarbon and climate shifts during the last deglaciation

Radiocarbon data from the Cariaco Basin provide calibration of the carbon-14 time scale across the period of deglaciation (15,000 to 10, 000 years ago) with resolution available previously only from Holocene tree rings. Reconstructed changes in atmospheric carbon-14 are larger than previously thought, with the largest change occurring simultaneously with the sudden climatic cooling of the Younger Dryas event. Carbon-14 and published beryllium-10 data together suggest that concurrent climate and carbon-14 changes were predominantly the result of abrupt shifts in deep ocean ventilation.

P-Glycoprotein inhibitor valspodar (PSC 833) increases the intracellular concentrations of daunorubicin in vivo in patients with P-glycoprotein-positive acute myeloid leukemia

PURPOSE

The aim of the present study was to evaluate the effect of the cyclosporine derivative valspodar (PSC 833; Amdray, Novartis Pharma, Basel, Switzerland) on the concentration of daunorubicin (dnr) in leukemic blast cells in vivo during treatment.

PATIENTS AND METHODS

Ten patients with acute myeloid leukemia (AML) were included. Leukemic cells from seven of the patients were P-glycoprotein (Pgp)-positive. dnr 100 mg/m(2) was given as a continuous infusion over 72 hours. After 24 hours, a loading dose of valspodar was given, followed by a 36-hour infusion of 10 mg/kg per 24 hours. Blood samples were drawn at regular intervals, and concentrations of dnr and its main metabolite, daunorubicinol, in plasma and isolated leukemic cells were determined by high-pressure liquid chromatography.

RESULTS

The mean dnr concentrations in leukemic cells 24 hours after the start of infusion (before valspodar) were 18.8 micromol/L in Pgp-negative samples and 13.5 micromol/L in Pgp-positive samples. After 8 hours of valspodar infusion, these values were 25.8 and 24.0 micromol/L, respectively. The effect of valspodar was evaluated from the ratio of the area under the curve (AUC) for dnr concentration versus time in leukemic cells to the AUC for dnr concentration against time in the plasma. For the seven patients with Pgp-positive leukemia, the mean ratio increased by 52%, from 545 on day 1 to 830 on day 2 (P<.05) when valspodar was given. In the three patients with Pgp-negative leukemia, no significant difference was observed.

CONCLUSION

These results strongly suggest that valspodar, by interacting with Pgp, can increase the cellular uptake of dnr in leukemic blasts in vivo.

How animals move: an integrative view

Recent advances in integrative studies of locomotion have revealed several general principles. Energy storage and exchange mechanisms discovered in walking and running bipeds apply to multilegged locomotion and even to flying and swimming. Nonpropulsive lateral forces can be sizable, but they may benefit stability, maneuverability, or other criteria that become apparent in natural environments. Locomotor control systems combine rapid mechanical preflexes with multimodal sensory feedback and feedforward commands. Muscles have a surprising variety of functions in locomotion, serving as motors, brakes, springs, and struts. Integrative approaches reveal not only how each component within a locomotor system operates but how they function as a collective whole.

Factors associated with brain donation among optimally healthy elderly people

BACKGROUND

Consent rates for brain donation were examined in 140 healthy elderly participants of the Oregon Brain Aging Study, a longitudinal study of successful aging. Subjects were initially selected for good health. The study population had a relatively high education level, a high socioeconomic status, and were predominantly white.

METHODS

At each annual examination, a project physician asked participants to consider brain donation. This analysis examined variables that may affect the rate of brain donation consent: age, gender, education, socioeconomic status, marital status, religiosity, cognitive status, depression, and functional status.

RESULTS

Of these variables only age was a meaningful factor.

CONCLUSION

The oldest old participants (> or =85 years of age) were more likely to consent to donation than the younger participants (65-84 years of age).

Subtropical North Atlantic Temperatures 60,000 to 30,000 Years Ago

A reconstruction of sea surface temperature based on alkenone unsaturation ratios in sediments of the Bermuda Rise provides a detailed record of subtropical climate from 60,000 to 30,000 years ago. Northern Sargasso Sea temperatures changed repeatedly by 2 degrees to 5 degrees C, covarying with high-latitude temperatures that were previously inferred from Greenland ice cores. The largest temperature increases were comparable in magnitude to the full glacial-Holocene warming at the site. Abrupt cold reversals of 3 degrees to 5 degrees C, lasting less than 250 years, occurred during the onset of two such events (Greenland interstadials 8 and 12), suggesting that the largest, most rapid warmings were especially unstable.

High single dose of mitoxantrone and cytarabine in acute non-lymphocytic leukemia: a pharmacokinetic and clinical study

In a phase I-II study, the authors evaluated the intracellular pharmacokinetics, toxicity, and efficiency of a high dose of mitoxantrone given as first induction in acute non-lymphocytic leukemia. Twenty-two patients with previously untreated de novo ANLL were included and received 30 or 40 mg/m2 mitoxantrone on day 1 by intravenous infusion over 1 hour and 500 mg/m2 ara-C twice a day for 5 days. If there was no complete remission (CR), a second induction with ara-C, etoposide, and amsacrine was given. The CR rate after two courses with this regimen was 77%. Median duration of severe neutropenia was 18 days in the 30-mg/m2 group and 25 days in the 40-mg/m2 group. Two patients had fatal lung complications probably unrelated to mitoxantrone. A third patient had a possible mitoxantrone-induced reversible lung complication. In the leukemic cells, we found a high accumulation of mitoxantrone which, in contrast to the plasma concentration, remained stable during the 48 hours studied. Compared with previous results with 12 mg/m2 mitoxantrone, the AUC for intracellular concentrations versus time for the first 20 hours studied was increased by 150% to 0.638 nmol/mg cell protein x hour with 30 mg/m2 mitoxantrone and by 260% to 1.103 nmol/mg cell protein x hour with 40 mg/m2 mitoxantrone. In conclusion, a high dose of mitoxantrone results in a high intracellular exposure of the leukemic cells, which may be an advantage in improving survival of these patients.

Synchronous climate changes in antarctica and the north atlantic

Central Greenland ice cores provide evidence of abrupt changes in climate over the past 100,000 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic, confirming the link between millennial-scale climate variability and ocean thermohaline circulation. It is shown here that two of the most prominent North Atlantic events-the rapid warming that marks the end of the last glacial period and the Bolling/Allerod-Younger Dryas oscillation-are also recorded in an ice core from Taylor Dome, in the western Ross Sea sector of Antarctica. This result contrasts with evidence from ice cores in other regions of Antarctica, which show an asynchronous response between the Northern and Southern Hemispheres.

Establishment of behavioral parameters for the evaluation of osteopathic treatment principles in a rat model of arthritis

Unilateral arthritis was produced in rats by use of methylated bovine serum albumin in a model of antigen-induced arthritis. The progression of arthritis was measured by computerized motion analysis, bilateral joint circumference, voluntary extension force of the hindlegs, and length of ankle extension. Animals with induced arthritis were assigned to treated and untreated groups on the basis of approximately equal deficits by the parameters measured. A third group of rats, which did not have arthritis induced and received no treatment, served to establish mean normal parameters. Modified techniques of muscle energy, passive movement of the ankle and knee, and passive myofascial stretch were applied to the animals, and the animals were exercised in a mechanized exercise wheel. Parameters associated with gait were examined by computerized motion analysis of walking. Animals treated with manipulation and exercise improved significantly relative to untreated animals with antigen-induced arthritis in vertical ankle lift, ankle-based and foot-based stride lengths, knee circumference, and normalized extension of the ankle. The results demonstrate that the parameters identified can be used to detect functional deficits and significant improvement from those deficits can be derived from a nonpharmacologic treatment paradigm that includes osteopathic manipulation and exercise in an animal model of arthritis. These parameters may be useful in the identification of the relative benefits of independent treatment variables including frequency of osteopathic manipulation and exercise and the relative benefits of each in this model. Also, they may elucidate how these treatments produce their beneficial effects clinically.

Talking while walking: the effect of a dual task in aging and Alzheimer's disease

We determined the effects of distraction on gait in healthy elderly subjects and Alzheimer's disease (AD) patients. The effects of simultaneous performance of a verbal fluency task (effect of reciting male or female names) on the time and number of steps taken to walk 30 feet were compared using a repeated-measures design with between-group comparison between community-dwelling healthy old old (oOld; n = 20; mean age +/- SD, 86 +/- 4.4), healthy young old (yOld; n = 23; mean age +/- SD, 72 +/- 3.6), and probable AD subjects without parkinsonism (n = 15; mean age +/- SD, 74 +/- 13). AD patients slowed more than the yOld (p = 0.005) and the oOld (p = 0.002). The yOld and oOld did not differ from each other (p = 0.68). Mean (+/-SD) differences in time were as follows: yOld, -2.2 +/- 1.9; oOld, -1.6 +/- 2.0; AD, -7.1 +/- 9.2 seconds. The change in steps did not differ between groups. Walking speed of AD patients slowed more than that of elderly subjects during the dual task. This may contribute to the risk of falls in AD.

Sensitivity functions of a human head movement model

With time as the criterion to be optimized, the divergences from optimal head movements show systematic differences of their control signal variables with respect to single behaviours. To clarify these relationships, this study uses manipulation and mathematical analysis of the 6th order nonlinear head movement model, i.e. the threefold approach of sensitivity analysis. In addition to sensitivity coefficients, graphs and trajectories sensitivity functions have been analysed. This is the sensitivity of a nominal head movement to changes of the model parameters during the time course of the movement. This demonstrated both the specific change of the visco-inertial properties of the head movement model during the movement and also the potential pathological deficits that may occur.

Mid-Depth Circulation of the Subpolar North Atlantic During the Last Glacial Maximum

Holocene and glacial carbon isotope data of benthic foraminifera from shallow to mid-depth cores from the northeastern subpolar Atlantic show that this region was strongly stratified, with carbon-13-enriched glacial North Atlantic intermediate water (GNAIW) overlying carbon-13-depleted Southern Ocean water (SOW). The data suggest that GNAIW originated north of the polar front and define GNAIW end-member carbon isotope values for studies of water-mass mixing in the open Atlantic. Identical carbon isotope values in the core of GNAIW and below the subtropical thermocline are consistent with rapid cycling of GNAIW through the northern Atlantic. The high carbon isotope values below the thermocline indicate that enhanced nutrient leakage in response to increased ventilation may have extended into intermediate waters. Geochemical box models show that the atmospheric carbon dioxide response to nutrient leakage that results from an increase in ventilation rate may be greater than the response to nutrient redistribution by conversion of North Atlantic deep water into GNAIW. These results underscore the potential rule of Atlantic Ocean circulation changes in influencing past atmospheric carbon dioxide values.

Human studies to measure the effect of antibiotic residues

This epidemiological study compares the frequency of resistant bacteria in stool microflora among vegetarians and nonvegetarians over a 12 month period. Two well characterized vegetarian populations (one in Boston, MA and the other in Loma Linda, CA) as well as appropriate controls were studied. No apparent differences in the prevalence of antibiotic resistance in the microflora were noted; however, vegetarians had a significantly greater incidence of multi-antibiotic resistance. E. coli of the same API biotype had the same frequency of antibiotic resistance in both vegetarians and nonvegetarians. Quantitative studies showed similar percents of tetracycline resistant facultative isolates and of "bacteroides." Klebsiella were more common in the stool of the nonvegetarians. As shown in previous studies, exposure to animal products either as meat eaters or production workers in a poultry abattoir was not associated with an increased incidence of resistant bacterial flora or infections caused by resistant strains.

Sensitivity coefficients, trajectories and graphs of a human head-movement model

With time as the criterion to be optimized, the divergences from optimal head movements show systematic differences in their control signal variables with respect to single behaviours. To clarify these relationships, this study applies manipulation and mathematical analysis of the 6th-order nonlinear head movement model, using the three-fold approach of sensitivity analysis. The sensitivity analysis of the improved and refined head movement model explains the different tasks of the control parameters and their relation to the plant. It shows that width more than height of the agonistic and antagonistic pulses dominate the important behaviours of the movement: acceleration, magnitude and duration.

Regional differentiation in the stomach of the green anole

The stomach of Anolis carolinensis (Reptilia: Iguanidae) has four histologically and histochemically distinct regions. The gastroesophageal junction has an acidic surface mucin and no glands. The cardia has an acidic surface mucin and mucous glands. This acidic mucin appears to contain neither sulfates nor sialic acid. The fundus has a neutral surface mucin and mucoserous glands. The pylorus has a neutral surface mucin and mucous glands.

Simulation of head movement trajectories: model and fit to main sequence

A sixth order nonlinear model for horizontal head rotations in humans is presented and investigated using experimental results on head movement trajectories and neck muscle EMG. The controller signals, structured in accordance with time optimal control theory, are parameterized, and controller signal parameter variations show a dominating influence on different aspects of the head movement trajectory. The model fits the common head acceleration types over a wide range of amplitudes, and also less common (dynamic overshoot) trajectories.

Sensitivity analysis and optimization for a head movement model

A sixth order nonlinear model for horizontal head rotations in humans is analyzed using an extended parameter sensitivity analysis and a global optimization algorithm. The sensitivity analysis is used in both the direct sense, as a model fitting tool, and in the indirect sense, as a guide to experimental design. Resolution is defined in terms of the sensitivity table, and is used to interpret the sensitivity results. Using sensitivity analyses, the head and eye movement systems are compared and contrasted. Controller signal parameters are the most influential. Their variations and effects on head movement trajectories and accelerations are investigated, and the conclusions are compared with clinical neurological findings. The global optimization algorithm, in addition to automating the fitting of various types of data, is combined with time optimality theory to give theoretical time-optimal inputs to the model.

Head rotation trajectories compared with eye saccades by main sequence relationships

A helmet apparatus permitted duration, peak velocity, and peak acceleration measurements as functions of magnitude of horizontal head rotation; these "main sequence" data give evidence for multipulse-step neurological signals appropriate for time optimal control of head rotation similar to those of saccadic eye movements.