Lower frequency of NPM1 and FLT3-ITD mutations in a South African adult de novo AML cohort

INTRODUCTION

Acute myeloid leukemia (AML) is a heterogeneous clonal disorder of hemopoietic progenitor cells diagnosed in individuals of any age, but with a median age of 67 years at presentation in adults. Assessment of the mutation status of nucleophosmin protein-1 (NPM1) and FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) is essential for the prognosis, and treatment of AML.

METHODS

A total of 160 de novo AML cases, both cytogenetically normal and abnormal, were analyzed for the presence of NPM1 and FLT3-ITD mutations, and the results assessed in conjunction with epidemiological, clinical, and laboratory findings.

RESULTS

Nucleophosmin protein-1 mutations were found in 7.5%, while FLT3-ITD was present in 12% of these cases. Both of these were lower than expected. The median age at diagnosis of AML was 41 years, and for the FLT3-ITD only cases, median age was 33 years; these ages were younger than expected.

CONCLUSION

The lower reported frequencies and younger median age at diagnosis of AML and these specific mutations may be contributed to by a number of factors including effects of race on age of presentation, inclusion of patients diagnosed with de novo AML only, and a generally younger median age of the South African population.

Asymmetrical attenuation of vibration sensation in unilateral diabetic Charcot foot neuroarthropathy

AIMS

To further characterize the distal sensory neuropathy in subjects with unilateral diabetic Charcot foot neuroarthropathy.

METHODS

A retrospective cohort study to assess the level to which the sensory modalities of pinprick, light touch, vibration, joint position and temperature were attenuated in the affected and unaffected limbs in subjects with unilateral Charcot. The level to which the sensory modality was attenuated in each limb was assigned a score. The Wilcoxon signed rank test was used to compare the scores in the affected and unaffected limbs and also to compare the scores of the different sensory modalities in the affected and unaffected limbs.

RESULTS

Fifty subjects with unilateral Charcot foot neuroarthropathy were assessed. Mean age was 45 ± SD 6 years for the 17 subjects with Type 1 diabetes and 62 ± 10 years for the 33 subjects with Type 2 diabetes. Duration of diabetes was 21 ± 13 years, HbA(1c) was 70 ± 19 mmol/mol [8.6 ± 1.8 %] and 15 subjects (30%) required renal replacement therapy. The level of attenuation of vibration sensation was more proximal in the affected compared with the unaffected limbs (P = 0.002). Pinprick, light touch, joint position and temperature sensations were not different. Joint position sensation was less attenuated bilaterally than the other sensory modalities.

CONCLUSIONS

Asymmetrical attenuation of vibration sensation may predict the side that will develop a Charcot joint and may suggest a more important role for vibration sense loss than loss of other sensory modalities in the pathophysiology of Charcot.

Performance of subjects with and without severe mental illness on a clinical test of problem solving

Severe mental illness is associated with impairments in executive functions, such as conceptual reasoning, planning, and strategic thinking all of which impact problem solving. The present study examined the utility of a novel assessment tool for problem solving, the Rapid Assessment of Problem Solving Test (RAPS) in persons with severe mental illness. Subjects were 47 outpatients with severe mental illness and an equal number healthy controls matched for age and gender. Results confirmed all hypotheses with respect to how subjects with severe mental illness would perform on the RAPS. Specifically, the severely mentally ill subjects (1) solved fewer problems on the RAPS, (2) when they did solve problems on the test, they did so far less efficiently than their healthy counterparts, and (3) the two groups differed markedly in the types of questions asked on the RAPS. The healthy control subjects tended to take a systematic, organized, but not always optimal approach to solving problems on the RAPS. The subjects with severe mental illness used some of the problem solving strategies of the healthy controls, but their performance was less consistent and tended to deteriorate when the complexity of the problem solving task increased. This was reflected by a high degree of guessing in lieu of asking constraint questions, particularly if a category-limited question was insufficient to continue the problem solving effort.

Planar imaging versus gated blood-pool SPECT for the assessment of ventricular performance: a multicenter study

Gated blood-pool SPECT (GBPS), inherently 3-dimensional (3D), has the potential to replace planar equilibrium radionuclide angiography (ERNA) for computation of left ventricular ejection fraction (LVEF), analysis of regional wall motion (RWM), and analysis of right heart function. The purpose of this study was to compare GBPS and ERNA for the assessment of ventricular function in a large, multicenter cohort of patients.

METHODS

One hundred seventy-eight patients referred in the usual manner for nuclear medicine studies underwent ERNA followed by GBPS. Each clinical site followed a GBPS acquisition protocol that included 180 degrees rotation, a 64 by 64 matrix, and 64 or 32 views using single- or double-head cameras. Transverse GBPS images were reconstructed with a Butterworth filter (cutoff frequency, 0.45-0.55 Nyquist; order, 7), and short-axis images were created. All GBPS studies were processed with a new GBPS program, and LVEF was computed from the isolated left ventricular chamber and compared with standard ERNA LVEF. Reproducibility of GBPS LVEF was evaluated, and right ventricular ejection fraction (RVEF) was computed in a subset of patients (n = 33). Using GBPS, RWM and image quality from 3D surface-shaded and volume-rendered cine displays were evaluated qualitatively in a subset of patients (n = 30).

RESULTS

The correlation between GBPS LVEF and planar LVEF was excellent (r = 0.92). Mean LVEF was 62.2% for GBPS and 54.1% for ERNA. The line of linear regression was GBPS LVEF = (1.04 x ERNA LVEF) + 6.1. Bland-Altman plotting revealed an increasing bias in GBPS LVEF with increasing LVEF (Y = 0.13x + 0.61; r = 0.30; mean difference = 8.1% +/- 7.0%). Interoperator reproducibility of GBPS LVEF was good (r = 0.92). RVEF values averaged 59.8%. RWM assessment using 3D cine display was enhanced in 27% of the studies, equivalent in 67%, and inferior in 7%.

CONCLUSION

GBPS LVEF was reproducible and correlated well with planar ERNA. GBPS LVEF values were somewhat higher than planar ERNA, likely because of the exclusion of the left atrium.

Technical competency in flexible sigmoidoscopy

BACKGROUND

Family practice residencies offer training in flexible sigmoidoscopy; however, there are no objective recommendations for determining competency in learners. We describe a longitudinal study designed to determine the mean procedure time and depth of insertion for family practice residents.

METHODS

During a 21-month period, data were collected for 421 patients undergoing flexible sigmoidoscopy. Second- or third-year family medicine residents supervised by family medicine faculty did all procedures. The data were analyzed with simple descriptive statistics, t test, and linear and logistic regression.

RESULTS

The mean procedure time was 18+/-9.3 minutes (17.2 - 19.6, 95% confidence interval [CI]). The mean insertion depth was 51.4+/-12.4 cm (50.4 - 52.6 cm, 95% CI). Performing a biopsy was associated with an increase in procedure time (17.0 vs 27.3 minutes, P < .0001). Women with a history of pelvic surgery had less depth of insertion than did those who had no history of pelvic surgery (47 vs 53 cm, P = .002, t test).

CONCLUSION

Procedural competency consists of knowledge, technical skills, and attitudes. Knowledge and attitudes can be assessed with other items, such as examinations and observation. Primary care faculty can now use these standards of insertion depth and procedure time when determining technical skill proficiency for their residents in flexible sigmoidoscopy.

Kinetic analysis of 125I-iodorotenone as a deposited myocardial flow tracer: comparison with 99mTc-sestamibi

The goal of this investigation was to assess the accuracy of 7'-Z-[125I]iodorotenone (125I-iodorotenone) as a new deposited myocardial flow tracer and compare the results with those for 99mTc-sestamibi.

METHODS

The kinetics of these two flow tracers were evaluated in 25 isolated, erythrocyte- and albumin-perfused rabbit hearts over a flow range relevant to patients. The two flow tracers and a vascular reference tracer (131I-albumin) were introduced simultaneously as a compact bolus through a port just above the aortic cannula in the absence of tracer recirculation. Myocardial extraction, retention, washout, and uptake parameters were computed from the venous outflow curves using the multiple-indicator dilution technique and spectral analysis.

RESULTS

The extraction of 125I-iodorotenone was much higher than the extraction of 99mTc-sestamibi (0.84 +/- 0.05 vs. 0.48 +/- 0.10, respectively, P < 0.001). 125I-iodorotenone extraction was also less affected by flow than was 99mTc-sestamibi (P < 0.001). Net retention of 125I-iodorotenone was significantly greater than 99mTc-sestamibi net retention at 1 min (0.77 +/- 0.08 vs. 0.41 +/- 0.11, respectively, P < 0.001) and 26 min (0.46 +/- 0.13 vs. 0.27 +/- 0.11, respectively, P < 0.001) after tracer injection. Flow had less effect on 125I-iodorotenone net retention than on 99mTc-sestamibi net retention 1 min after tracer injection (P < 0.04). However, at 26 min, flow had an equivalent effect on the retention of both flow tracers (P < 0.4). The relationship between 125I-iodorotenone and 99mTc-sestamibi washout was complex and depended on elapsed time after isotope introduction and perfusion rate. Reflecting the favorable extraction and retention characteristics of 125I-iodorotenone, both its maximum myocardial uptake and its 26-min uptake were more closely related to flow than were those of 99mTc-sestamibi (P < 0.001 for both comparisons).

CONCLUSION

The extraction and retention of 125I-iodorotenone were greater than those of 99mTc-sestamibi, making 125I-iodorotenone the superior flow tracer in the isolated rabbit heart.

Quantitative gated blood pool SPECT for the assessment of coronary artery disease at rest

BACKGROUND

Planar gated blood pool imaging (GBPI) has long proven to be useful for the noninvasive assessment of ventricular function. From a practical viewpoint, gated blood pool single photon emission computed tomography (GBPS) acquisition can be accomplished in the same time as a three-view planar series, with the benefit of a tomographic perspective that avoids chamber overlap.

METHODS AND RESULTS

Quantitative gated blood pool SPECT was applied to 10 patients who underwent coronary arteriography, contrast ventriculography, and planar gated blood pool imaging. For each patient, the mid-short axis oblique slice was divided into 4 discrete segments using 4 different reference models and 2 forms of segmentation. A center of mass (counts) fixed in the end-diastolic frame and segmentation that bisected the ventricular septum proved to have the highest sensitivity and specificity for determining regional wall motion abnormalities at rest in myocardium supplied by severely diseased coronary arteries (>75 %). GBPS correctly identified 19 of 21 abnormal segments (90%), with good specificity (95%), whereas ventriculography identified 12 (57%) and planar GBPI identified 9 (43%) of the segments supplied by diseased coronaries.

CONCLUSION

Quantitative GBPS appears to be a sensitive method for assessing coronary artery disease at rest in myocardium perfused by severely diseased coronary arteries.

Estimating glucose metabolism using glucose analogs and two tracer kinetic models in isolated rabbit heart

The purpose of this investigation was to 1) evaluate the relative accuracy of the Sokoloff and Patlak tracer kinetic models in estimating glucose metabolic rate (GMR) in the presence and absence of insulin; 2) evaluate the effect of nutritional state on the lumped constant (LC); and 3) compare the kinetics of 2-fluoro-2-deoxy-D-[14C]glucose (FDG) and 2-deoxy-D-[3H]glucose (DG) membrane transport and phosphorylation. The experimental preparation was the isolated, red blood cell-albumin-perfused rabbit heart. Our results showed that both tracer kinetic models provided GMR estimates that correlated well with the Fick method (for FDG, R = 0. 84 and 0.91 for the Sokoloff and Patlak models, respectively); nutritional state did not affect the LC; and FDG and DG have different transport and/or phosphorylation parameters. We also observed that 1) the addition of a fourth compartment to the Sokoloff model reduced the mean squared error between measured and modeled data by a factor of 7.4; 2) a longer time (21.8 min) was required to obtain a linear phase of the Patlak plot than is allowed in clinical studies; and 3) accurate GMR estimates were obtained only by using different LCs reflecting insulin's presence or absence. Our results indicate potential sources of error in the use of FDG and positron emission tomography to quantify GMR in patients.

Retrieval of famous names on a Rebus Riddle task by middle-aged and older subjects

This study compared the performances of 20 middle-aged and 20 older subjects on a Rebus Riddle task that required they retrieve the names of famous persons. Older subjects solved significantly more riddles and responded to prompts designed to aid riddle-solving efforts with significantly greater success than middle-aged subjects. Older subjects also had nonsignificantly faster riddle-solving times than middle-aged subjects. Similar riddles were difficult or easy for both groups. Superior performance of the older group appeared to be related to the age of the subject at the time the persons in the riddles had become famous.

Kinetic analysis of rubidium and thallium as deposited myocardial blood flow tracers in isolated rabbit heart

Evaluation of myocardial perfusion with tracers such as thallium and rubidium is based on the assumption that tissue tracer content is proportional to flow. The purpose of this study was to evaluate the relationship between flow and tissue tracer content of 201Tl and 83Rb in the isolated perfused rabbit heart. 83Rb (86-day half-life), an isotope that is not used clinically, was used as a subsitute for 82Rb (76-s half-life) to improve the accuracy and precision of data acquisition. The multiple indicator-dilution technique was employed with two independent computational approaches. The first approach explicitly deconvolved 201Tl and 83Rb venous concentration curves by the intravascular reference tracer curve. The second approach used a conventional analysis. Both approaches showed that there was more early washout of 83Rb than 201Tl and that the heart retained 201Tl better than 83Rb within 2 min after isotope introduction. These data indicate that 201Tl is a better perfusion tracer than 83Rb in the isolated rabbit heart.

Comparison of personalized cueing and provided cueing on the facilitation of verbal labeling by aphasic subjects

This study investigated the effects of two associative learning tasks on aphasic subjects' labeling of novel symbols. It was designed to determine if aphasic subjects need to develop their own associations for word-symbols pairs (personalized cueing) to obtain the long-term labeling benefits observed in prior research or if comparable results are obtained when "ready-made" associations are used during training (provided cueing). The results showed that the two cueing techniques were equal in their ability to elicit correct responses from the subjects. The results also demonstrated the long-term effectiveness of both cueing procedures on the subjects' labeling accuracy up to 30 days after training was discontinued.

Morphological and biochemical characteristics of trichothiodystrophy-variant hair are maintained after grafting of scalp specimens on to nude mice

Trichothiodystrophy (TTD) is a hair defect associated with abnormal composition of the high-sulphur proteins (HSP). HSP can be modified quantitatively (reduced amount of qualitatively normal HSP: TTD-variant) and qualitatively (TTD). In this study we show that the amino acid composition of hairs collected from the scalp of a patient with TTD-variant (donor) was preserved in hairs produced by donor scalp follicles maintained up to 6 months as grafts on to nude mice. It is the first time that an exceptionally rare, clinically and biochemically well-characterized hair dysplasia has been maintained under laboratory conditions for a long period of time. The linear growth rate of TTD-variant hairs was similar to that of control hairs grown under comparable conditions. The persistence of disease-specific abnormalities in the hair shaft indicates that the TTD-variant mutation is expressed without significant quantitative modifications, and appears independent of systemic host-related factors. This model may serve as a clinically relevant working platform for evaluating regulation of abnormal gene expression in the hair follicle under well-controlled experimental conditions.

The effect of flow on technetium-99m-teboroxime (SQ30217) and thallium-201 extraction and retention in rabbit heart

In order to evaluate the accuracy of blood flow measurement, the single-pass extraction, retention/wash-out and relative net uptake of 99mTc-teboroxime (SQ30217) and 201Tl were evaluated and compared in 20 isolated blood-perfused rabbit hearts at coronary flow rates ranging from 0.49 to 2.85 ml/g wet wt min-1. The average peak extraction of 201Tl (+/- s.d.) (0.67 +/- 0.11) marginally exceeded that of SQ30217 (0.62 +/- 0.12) (p = 0.06). Flow significantly affected the maximum net extraction of 201Tl and the 40-min net extractions of both 201Tl and SQ30217. Unexpectedly, the rate of 201Tl myocardial washout was significantly faster (p less than 0.05) than SQ30217 washout at all flow rates evaluated. Increasing coronary blood flow rate was associated with a more rapid clearance of both tracers from the myocardium (p less than 0.05 for both comparisons). The slope of the linear correlations between relative net SQ30217 uptake versus flow and relative net 201Tl uptake versus flow were found to be similar for up to 10 min after isotope injection. These data were interpreted to indicate that: 1. Thallium-201 might be slightly better extracted than SQ30217. 2. SQ30217 is cleared more slowly from the myocardium. 3. Thallium-201 and SQ30217 appear to be comparable tracers of myocardial perfusion for up to 10 min after injection under the single-pass conditions currently employed. 4. Additional studies are needed to clarify myocardial SQ30217 kinetics.

Structure and biochemistry of mammalian hard keratin

In this review, the structure and biological formation of hard alpha-keratin are drawn together. The hard keratins comprising wool, hairs, quills, hooves, horns, nails and baleen contain partly alpha-helical polypeptides which show homology with epidermal polypeptides only in the helical regions. These polypeptides (about 32 chains) are organized into intermediate filaments (IFs) of 7.5 nm diameter which are embedded in variable amounts of a matrix of non-helical cystine-rich proteins and glycine-tyrosine-rich proteins. The total number of proteins may exceed 100. In addition keratins contain a variety of lipid components. Wool and hair are produced in follicles in a multistep procedure. In the lower levels of the follicle, IFs without associated matrix are found. Subsequently matrix proteins are laid down between the IFs and further synthesis takes place concurrently. Finally the proteins are insolubilized by the oxidative formation of disulphide bonds. Keratinized fibres shows considerable complexity and diversity in the structural arrangement of IFs and matrix within cortical cells. Typically the IFs show hexagonal packing or give a whorl-like appearance in cross-section.

Technetium-99m hexakis 2-methoxy-2-isobutyl isonitrile and thallium-201 extraction, washout, and retention at varying coronary flow rates in rabbit heart

Technetium-99m hexakis 2-methoxy-2-isobutyl isonitrile (Tc-MIBI) and thallium-201 extraction, washout, and retention were investigated and compared in 20 isolated, isovolumic, retrograde blood-perfused rabbit hearts at flow rates ranging from 0.5 to 3.5 ml/g wet wt min-1 in the absence of tracer recirculation. Mean Tc-MIBI peak instantaneous extraction was lower (0.55 +/- 0.10, p less than 0.001) and more affected by flow rate (p less than 0.05) than 201Tl peak instantaneous extraction (0.83 +/- 0.06). In contrast, the rate of 201Tl washout was significantly faster (p less than 0.05) and initially more dependent on perfusion rate (p less than 0.05) than Tc-MIBI washout. Reflecting its higher peak instantaneous extraction, 201Tl retention was 55-79% higher immediately after isotope injection (p less than 0.001) than Tc-MIBI retention, and relative changes in maximal 201Tl net uptake correlated better (p less than 0.05) with relative flow changes than maximal Tc-MIBI net uptake. However, due to its faster washout rate, the superiority of thallium over Tc-MIBI as a perfusion indicator was lost within 10 minutes of tracer injection under the present single-pass experimental conditions. These data were interpreted to indicate that 1) Tc-MIBI is not as well extracted and has a slower washout rate than 201Tl; 2) varying the coronary flow rate has significant but divergent effects on the extraction, washout, and retention of Tc-MIBI and 201Tl; and 3) the present results support continued evaluation of Tc-MIBI as a possible perfusion indicator.

Home treatment for aphasic patients by trained nonprofessionals

Thirty-seven aphasic men received 8-10 hr of individual treatment each week for 12 weeks from a home therapist (wife, friend, relative) who was trained and directed by a speech pathologist. Treatment was followed by 12 weeks of no treatment. Patients were evaluated at entry and at 6, 12, 18, and 24 weeks after entry with a battery of speech and language measures. The group made substantial progress on all measures during the 12 weeks of treatment and ceased to progress when treatment was discontinued. Progress for the home treatment patients did not differ significantly from that of patients who received 12 weeks of individual treatment from speech pathologists or from that of patients for whom treatment was deferred for 12 weeks. Patient selection, training of the home therapists, and other methodological aspects are described to assist speech pathologists in making decisions about the use of trained volunteers in aphasia treatment.

Identification of persons at risk for sudden cardiac death

Before any more progress is made in reducing the incidence of sudden cardiac death, our ability to identify those at risk must be refined further. The close association with coronary artery disease necessitates that the first step must be the identification of those with underlying coronary artery disease. This is underscored by the disturbing fact that, in many, sudden death is the first sign of coronary disease. An aggressive evaluation of those with significant risk factors appears justified. The second part of the problem is the identification of those with coronary artery disease who are at especially high risk. The current diagnostic modalities available suffer from a relative lack of specificity to be applied indiscriminately in light of the expense and morbidity of effective therapies (that is, coronary artery bypass surgery, antiarrhythmic drugs, implantable defibrillators, surgical or catheter ablation). At the present time, we can identify certain subsets that warrant aggressive therapy: survivors of sudden death events or sustained ventricular tachycardia, obstructive cardiomyopathies, aortic stenosis, left main coronary artery disease, and congenital QT prolongation. Less aggressive but also less specific therapies, such as beta-blockers in myocardial infarction survivors, can be given more indiscriminately. Ultimately, of course, the greatest impact will come from prevention of coronary artery disease.

Correlation of contractile dysfunction with oxidative energy production and tissue high energy phosphate stores during partial coronary flow disruption in rabbit heart

The relationships between contractile function, myocardial oxygen consumption, and tissue high energy phosphate and lactate content were investigated during partial coronary flow disruption. The experimental preparation was an isolated, isovolumic retrograde blood-perfused rabbit heart. Both developed pressure (r = 0.94) and dp/dt (r = 0.95) exhibited strong linear correlations with myocardial oxygen consumption that were stable for up to 45 min after blood flow reduction. In contrast, tissue high energy phosphate content exhibited nonlinear relationships with both developed pressure and oxygen consumption such that systolic mechanical function and oxidative metabolism declined to 20 and 30% of control values, respectively, before significant abnormalities in myocardial high energy phosphate stores were observed. Similarly, developed pressure and oxygen consumption decreased to 36 and 48% of control, respectively, before abnormal tissue lactate content was detected. The results of this study indicate that: (a) mechanical function is closely related to the rate of oxidative energy production during partial coronary flow disruption, and (b) despite the development of significant contractile dysfunction, tissue high energy phosphate content remains at normal levels except under the most severely flow-deprived conditions. The preservation of tissue energy stores can be explained by the apparent coupling of contractile performance to oxidative energy production, which could function to maintain myocardial energy balance during partial coronary flow restriction.

Response to exercise after withdrawal from chronic alcoholism

To test for early evidence of alcoholic cardiomyopathy and to assess changes in exercise response after abstinence, 12 asymptomatic alcoholic men (group 1) underwent maximal upright bicycle exercise radionuclide ventriculography two to six days after alcohol withdrawal. Six of these patients (group 1A) had similar testing two to four weeks later. Six control subjects (group 2) had repeated exercise tests without isotope study. Group 1 left ventricular ejection fraction response (LVEF) was normal. LVEF at similar workloads did not differ in group 1A (p = NS). However, unlike group 2 results, the linear regression line relating double product to exercise stage in group 1A was higher at first exercise (p less than 0.05), probably due to the effects of alcohol withdrawal. We conclude that radionuclide left ventriculographic findings in these patients do not support the concept of a preclinical alcoholic cardiomyopathy made apparent by exercise, and exercise very early after alcohol withdrawal is associated with an increased myocardial oxygen demand at any given workload.

Studies of developing human hair shaft cells in vitro

Methods for studying aspects of hair formation in vitro have been devised on the basis of isolating developing hair shaft cells. These cells were obtained using a sterile microdissection technique. Plucked anagen follicles were dissected free of surrounding tissues (inner and outer root sheaths), and presumptive hair shaft cells (including germinal epithelia) were cultured directly on mammalian fibroblasts or in media preconditioned by fibroblasts. Specimens were cultured either as dispersions or in whole tissue pieces. Trypsinized whole tissue specimens in culture were sometimes observed to form increased bulk, while dispersed cells appeared to elongate and form larger colonies. In sections of these colonies examined by transmission electron microscopy, intracellular hard keratin intermediate filaments (IFs) together with IF-matrix hard keratin complexes were observed. Radiolabelled cysteine [35S] was added to cultures (3-20 days), showing a continuing but reduced synthesis of hard keratin IF proteins (low-sulfur) over the period of study. Matrix protein (high-sulfur) production was drastically reduced after 3 days. Monoclonal antibodies directed against hair keratin IF components were used in Western transfers and immunofluorescent studies to help assess the specificity of proteins synthesized in culture. Our observations indicate that, with some refinement, the presently described methods enable preparation of hair shaft precursor cells suitable for observing certain hair-forming processes in vitro.

Myocardial energy production and consumption remain balanced during positive inotropic stimulation when coronary flow is restricted to basal rates in rabbit heart

The effect on myocardial energy balance of increasing oxygen demand without altering basal myocardial perfusion rate was assessed in isolated, isovolumic, retrograde blood perfused rabbit hearts. Myocardial energy requirements were increased with paired stimulation. The capacity of rapid paired stimulation to increase mechanical energy consumption was demonstrated in the presence of increased perfusion with the rate X pressure product and oxygen consumption increasing 86 and 148%, respectively, compared with control values. In contrast, rapid paired stimulation under constant, basal flow conditions did not alter the rate X pressure product, while oxygen extraction and consumption increased only 40% relative to control. Myocardial ATP, creatine-phosphate, and lactate content were identical under control and constant flow-paired stimulation conditions. The results of this study indicate that no detectable energy imbalance was produced by rapid paired stimulation with flow held constant at basal rates. These results suggest that the myocardium does not increase mechanical energy expenditure in response to inotropic or rate stimulation in the presence of restricted flow reserve and are inconsistent with the concept of "demand-induced" or "relative" myocardial ischemia.

Protein and amino acid composition of hair from mice carrying the naked (N) gene

The protein and amino acid compositions of hair from mice carrying the naked (N) gene were compared with those of wild-type (+ / +) mouse hair using two-dimensional polyacrylamide gel electrophoresis and amino acid analysis. In samples obtained from N /+ mice, the numbers of positions of the low-sulphur (LS), high-sulphur (HS) and high tyrosine (HT) protein spots were indistinguishable from those observed in + / + samples but the amount of HT protein was reduced in N / + hair. In samples obtained from N /N mice the protein spots were fewer than, and perhaps different from, those in samples from the other two genotypes; all protein classes were represented but the HS and HT protein content appeared to be less than that in + / + and N / + hair. Amino acid analyses of hair samples showed that the HS contents of + / + and N / + hair were approximately the same, whereas the HT protein content of N / + hair was about half that in + / + hair. N / N hair contained less half-cystine and tyrosine than + / + and N / + hairs, but because the contents of proline, threonine and glycine were unexpectedly high, it appears that protein components of unusual composition are present in N / N hair. It was concluded that the gene at the N locus is involved only indirectly in the synthesis of the structural proteins found in mouse hair.

Prognosis for improved verbal communication in aphasic stroke patients

Information for predicting to what degree a patient will recover from aphasia has not been available to the physician. This study examined the role of 10 selected prognostic variables in relation to recovery of verbal communication in a homogeneous sample of treated aphasic patients. Terminal speech performance (TSP) could be discriminated 86% of the time by 6 variables; (1) initial severity of aphasia, (2) number of months after stroke, (3) auditory comprehension ability, (4) age, (5) speech fluency, and (6) general health. The predictive value of these variables was slightly higher (91.2%) for patients with good TSP than for those with poor TSP (82.6%).

Assessment of the [18F]fluorodeoxyglucose kinetic model in calculations of myocardial glucose metabolism during ischemia

The lumped constant--a term in the operational equation of the Sokoloff tracer kinetic model for deoxyglucose that accounts for the difference in transport and phosphorylation between glucose and its analog, deoxyglucose--could potentially vary from normal to ischemic conditions in the heart. To test the stability of the lumped constant during ischemia, we evaluated the ratio of the extraction fraction for (F-18)-fluorodeoxyglucose (FDG) to that for glucose (a measure of the lumped constant if there is no significant dephosphorylation of FDG-6-PO4) and the rate constant for dephosphorylation of FDG-6-PO4 (k4*) in the isolated, arterially perfused interventricular septum of the rabbit during moderate and severe demand-induced and reduced-flow ischemias. The lumped constant and k4* in each of the four ischemic experimental conditions were found not to be significantly different from the value obtained from the nonischemic controls.

Characterization of the proteins of human hair and nail by electrophoresis

Low-sulfur and high-sulfur proteins from human hair and nail were characterized by two-dimensional polyacrylamide gel electrophoresis. Apparent molecular weights (estimated by SDS electrophoresis) of low-sulfur and high-sulfur proteins were in the ranges 55,500-76,000 and 26,500-43,000, respectively, but these are probably higher than the real values (12-30% for low-sulfur, 75-150% for high-sulfur) because corresponding wool proteins behave anomalously in SDS electrophoresis. Isoelectric points of the low-sulfur proteins ranged from 4.9-5.4. Six low-sulfur and 7 high-sulfur major proteins were common to hair and nail from the same individual, but each keratin contained 1 additional major low-sulfur component which was not common. Variation, presumably of genetic origin, was observed in the low-sulfur and high-sulfur proteins of hair and nail.

Identification and differentiation of resting myocardial ischemia and infarction in man with positron computed tomography, 18F-labeled fluorodeoxyglucose and N-13 ammonia

Studies have shown that the extraction of glucose per unit flow is increased in moderately ischemic myocardium primarily due to anaerobic glucose metabolism manifested as lactate production, whereas myocardial infarction is characterized by the loss of metabolically active myocardium. To determine the feasibility of demonstrating these metabolic abnormalities reflecting both ischemia and infarction, we used positron computed tomography (PCT) to evaluate relative regional myocardial exogenous glucose utilization and perfusion in 15 patients with recent myocardial infarction. The positron-emitting tracers of glucose metabolism and perfusion, 18F-2-fluoro-2-deoxyglucose (FDG) and N-13 ammonia, respectively, were used. Fourteen of 19 documented infarctions were demonstrated by PCT to have concordantly decreased glucose utilization and perfusion. However, in an additional 11 regions, glucose utilization was disproportionately increased relative to perfusion, consistent with ischemic glucose consumption. These findings correlated with the presence of postinfarction angina, the site of ischemic electrocardiographic changes during chest pain, and the presence of regional left ventricular dysfunction and severe coronary artery disease. Because three ECG infarct zones not detected by PCT demonstrated ischemic glucose utilization, only two of 19 electrocardiographically defined infarctions had no detectable metabolic abnormality. We conclude that the changes in regional FDG and N-13 ammonia concentrations detected with PCT in patients who had had a recent myocardial infarction are consistent with regional exogenous glucose utilization and perfusion in moderately ischemic and irreversibly infarcted myocardium. This approach has the potential to identify and differentiate resting myocardial ischemia from infarction and to assess tissue viability after an ischemic event.

Changes in the proteins of wool following treatment of sheep with epidermal growth factor

Administration of epidermal growth factor (EGF) extracted from mouse submaxillary gland to Merino sheep resulted in a temporary inhibition of the activity of the wool follicles. Subsequently, either complete discontinuities appeared in the fibers resulting in shedding of the entire fleece, or incomplete, in which case the fleece was retained but bore a zone of weakness. The protein composition of the first sample of wool harvested from 1 sheep following infusion for 66 hr with 27.5 mg EGF (0-2 weeks posttreatment) was similar to pretreatment wool. This represented wool fibers which were already present in the follicles at the beginning of infusion. Thereafter, the composition of the wool changed progressively, reaching a maximum divergence from the control in the 3-4 week regrowth period followed by a return to normal by about 10 weeks. Over this period the content of high-sulfur proteins first rose from an initial 19% to a maximum of 30%, then returned to 19%, while the high-tyrosine protein content initially decreased from 12% to 5% and then slowly increased to 12%. In addition to changes in overall protein composition, two-dimensional electrophoresis revealed alterations in the proportions of some individual protein components. These changes were similar to those observed with many other wool growth inhibitors. Smaller doses of EGF (5.8 and 2.9 mg but not 1 mg) had similar effects on wool composition but these were of lower magnitude and there was a delay in reaching a maximum response. Even after 16-18 weeks the wool from these treated sheep differed slightly in composition from the pretreatment samples.

The tryptophan-rich keratin protein fraction of claws of the lizard Varanus gouldii

1. Claw keratin of the lizard, Varanus gouldii, is composed mainly of 13,000 mr proteins rich in glycine and cystine. This study deals with a tryptophan-rich group of about 20 constituent proteins comprising about one-third of the mass. 2. As S-carboxymethylkerateines, these proteins were separated by fractional precipitation and gel filtration, then characterized by amino acid analysis, end group analysis, electrophoresis and ultracentrifugation. 3. It is considered that the majority of lizard claw proteins are more closely allied to those of avian beak and claw than feather proteins. 4. Claw keratin also contains minor proteins which resemble mammalian keratin high-tyrosine proteins.

The effects of topical and systemic glucocorticosteroids on DNA synthesis in different tissues of the hairless mouse

Two topical corticosteroids, clobetasol propionate and clobetasone butyrate, have been studied in hairless mice for their effects on DNA synthesis in the epidermis, thymus and spleen. Following topical application, both clobetasol propionate and clobetasone butyrate showed significant activity at the site of application throughout the range of concentrations tested (20 microliters; 0.0001-0.1%; 20 ng to 20 micrograms). However, whereas 20 ng clobetasol propionate also elicited significant effects in the distal (untreated) epidermis and the thymus, more than 2 micrograms of clobetasone butyrate were required to produce similar effects in these tissues. This finding was supported by the results obtained following intravenous administration of equivalent doses (0.01 and 0.001%; 200 microliters dose) of the same two steroids. Only clobetasol propionate showed significant activity in the epidermis and thymus. Clobetasone butyrate showed slight, non-significant effects in the epidermis at the highest concentration (200 microliters; 0.01%), but not in the thymus or spleen. An unexpected finding was that the effects following intravenous injection were generally lower than those following topical application. In conclusion, these results establish that (a) effects on DNA synthesis in the epidermis at a site distal to the application site are indicative of systemic activity from topically applied corticosteroids, (b) the thymus is especially sensitive to corticosteroids eliciting systemic effects and (c) an equivalent dose of a topical corticosteroid administered intravenously produces less inhibition of thymic and epidermal DNA synthesis than the same dose applied topically.

Identifying behavior associated with verbal self-corrections of aphasic clients

The purposes of this study were to define certain behaviors associated with verbal self-correction efforts of aphasic clients and to determine the accuracy with which these behaviors might be identified by clinical observers. Seven explicit definitions were written for behaviors associated wih aphasic clients' self-correction attempts on single-word and short-answer language production tasks. To determine the accuracy with which defined behaviors could be identified, observers (N = 7) were asked to view 400 randomly selected speech samples and to code the type of self-correction event for each sample. The accuracy of these judgments was ascertained by calculating the percentages of observers' agreements with judgments made previously by the experimenters. Results showed observers were able to identify explicitly defined behaviors at levels of accuracy ranging from 73%--99%. When observers' judgments did not agree with those of the experimenters, inaccuracies tended to be logical and to cluster in particular categories. Findings suggest a need for further study of behaviors associated with aphasic individuals' self-correction efforts, particularly with reference to the significance of these behaviors to recovery from aphasic, and to aphasic symptomatology in general.

Effect of oral propranolol on rest, exercise and postexercise left ventricular performance in normal subjects and patients with coronary artery disease

The effect of beta-adrenergic blockade with oral propranolol on resting, exercise and postexercise ventricular performance was evaluated using multiple-gated equilibrium cardiac blood and pool images in normal volunteers and patients with coronary artery disease. Propranolol produced no detectable effect on basal left ventricular function in normal subjects at doses producing intermediate (160 mg propranolol/day) and maximal (434 +/- 99 mg propranolol/day) beta blockade and in patients with coronary artery disease at clinically effective antianginal doses (162 +/- 47 mg propranolol/day). During exercise, a dose-related, negative inotropic effect was observed in normal subjects: 160 mg propranolol/day produced a small but statistically insignificant decline in exercise left ventricular performance, whereas maximal beta blockade significantly depressed the left ventricular response to exercise. In patients with coronary artery disease, propranolol's effect on exercise ventricular performance depended on the presence or absence of ischemic dysfunction during exercise. In patients with an ischemic functional response to exercise, propranolol significantly improved regional and global performance during and after exercise; in coronary artery disease patients with a normal response to exercise, propranolol had no significant effect on exercise and postexercise ventricular function. These results imply increased sensitivity to the effects of beta blockade in ischemic myocardium. In coronary artery disease patients with an abnormal response to exercise and in normal volunteers during beta blockade, propranolol's effect on exercise left ventricular performance was independent of changes in ventricular preload and after load related to heart rate and blood pressure.

Genetic variation in the proteins of human nail

In a survey of the proteins from human nail, genetic variation has been observed in both the low-sulfur and high-sulfur protein fractions. The low-sulfur proteins were examined by polyacrylamide gel electrophoresis at pH 7 in the presence of sodium dodecyl sulfate, whilst the high-sulfur proteins were characterized by gel electrophoresis at pH 2.6 in 3 M urea. Of 106 samples of apparently normal nail, 69% showed a characteristic pattern of 3 major low-sulfur and 5 major high-sulfur proteins. The remaining samples showed an additional high-sulfur band, and about half of these samples also manifested an additional major low-sulfur band. The proportion of nail samples containing the variant proteins was much higher in some families. Two-dimensional eletrophoresis of the low-sulfur proteins showed five major low-sulfur components in the normal nail with an additional component in the variant sample. Peptide maps of the proteins showed that the additional protein was sufficiently different in amino acid sequence to the other proteins to indicate that a mutation in a structural gene had not occurred. In the high-sulfur protein fractions, over 30 proteins were observed in the two-dimensional electrophoretic patterns and there were at least 3 additional components in the variant fraction.