Human heart: tagging with MR imaging--a method for noninvasive assessment of myocardial motion

Specified regions of the myocardium can be labeled in magnetic resonance (MR) imaging to serve as markers during contraction. The technique is based on locally perturbing the magnetization of the myocardium with selective radio-frequency (RF) saturation of multiple, thin tag planes during diastole followed by conventional, orthogonal-plane imaging during systole. The technique was implemented on a 0.38-T imager and tested on phantoms and volunteers. In humans, tags could be seen 60-450 msec after RF saturation, thus permitting sampling of the entire contractile phase of the cardiac cycle. Tagged regions appear as hypointense stripes, and their patterns of displacement reflect intervening cardiac motion. In addition to simple translation and rotation, complex motions such as cardiac twist can be demonstrated. The effects of RF pulse angle, relaxation times, and heart rate on depiction of the tagged region are discussed.

Femoral head avascular necrosis: MR imaging with clinical-pathologic and radionuclide correlation

A retrospective evaluation of magnetic resonance (MR) imaging for the detection of avascular necrosis (AVN) of the femoral head was performed in 49 patients (85 hips) with clinical suspicion of AVN. Positive findings at bone biopsy or evidence on plain radiographs was considered proof of AVN. Absence of clinical symptoms and of radiographic findings for a minimum of 18 months after MR imaging was considered evidence of the absence of AVN. All patients were studied with plain radiography and technetium-99m methylene diphosphonate bone scintigraphy. Five hips had negative MR images, positive findings at bone marrow biopsy, positive bone pressure measurement (BMP), and positive bone scans. A comparison between MR images and bone scans showed MR imaging to be superior, with a sensitivity of 88.8% (vs. 77.5%) and a specificity of 100% (vs. 75%). BMP was the most sensitive (92%) but least specific test (57%).

Dynamic stiffness measured in central segment of excised rabbit papillary muscles during barium contracture

The dynamic mechanical behavior of excised rabbit papillary muscles that had been tonically activated by replacing bathing Ca2+ with Ba2+ was studied. Steady activation was used to visualize the dynamic behavior of cardiac myofilaments more clearly than is possible during twitches, which are complicated by the kinetics of excitation-contraction coupling. To avoid artifacts due to damaged ends of the muscle, the length of a central segment, which was defined by 2 tungsten pins inserted through the muscle, was measured. To test the mechanical behavior of the contractured muscles (at 24 degrees C), the central segment length was sinusoidally oscillated (amplitude 1%) at 15 different frequencies (0.05-30 Hz). The dynamic stiffness of the central segment was calculated from the ratio of force response amplitude to length perturbation amplitude. At low frequencies (below 0.4 Hz), stiffness was approximately constant and reflected the force-length relation. However, in a localized range near 1 Hz, there was a distinct drop in the magnitude of dynamic stiffness to approximately half its low-frequency baseline. This range may reflect the dynamics of attachment and detachment of force generators. The frequency of minimum stiffness was consistent among all muscles (1.3 +/- 0.3 Hz). Moreover, no significant change in this frequency was found over the examined range of lengths (90-100% of the segment length that produced maximal developed force) and activation levels (Ba2+ concentration 0.3-1.0 mM). From 2 to 8 Hz, dynamic stiffness appeared to reflect force-velocity properties, but at higher frequencies, another elastic property emerged. At 30 Hz, stiffness was proportional to force, with an apparent series elasticity less than 1.8%. Even though the muscles had only moderate longitudinal inhomogeneity, quantitatively significant (35%) errors would have been introduced had the study relied on total muscle length instead of central segment length.

Control of lysozyme gene expression in differentiating HL-60 cells

We have investigated the control of lysozyme gene expression in HL-60 cells induced to differentiate into macrophage-like cells with phorbol myristate acetate (PMA). Differentiation, as evidenced by cellular adherence, and morphological changes corresponded temporally to an increase in nonspecific esterase activity. The lysozyme concentration in the medium of uninduced HL-60 cells was 10 micrograms/10(7) cells, increasing to a maximum of 46 micrograms/10(7) cells after 48 h incubation with PMA (16 nM). At 72 h the lysozyme concentration decreased to 16 micrograms/10(7) cells. Intracellular lysozyme activity remained constant throughout differentiation. If HL-60 cells were exposed to PMA for 24 h, washed, then maintained in normal medium, they differentiated normally, confirming their irreversible commitment to differentiate. The increase in lysozyme secretion by these cells, however, is markedly blunted suggesting that continued PMA treatment of differentiated cells is required for their secretion of lysozyme. There is no change in the rate of extracellular degradation of lysozyme during differentiation. The level of lysozyme mRNA does not correlate directly with the amount of lysozyme secreted into the medium. Hybridization of uninduced HL-60 cell RNA with a chicken lysozyme cDNA probe demonstrates moderate hybridization. There is a modest (five-fold) increase in lysozyme mRNA between 0 and 36 h of exposure to PMA, corresponding to the burst of lysozyme secretion by these cells. The lysozyme mRNA decreases to a level which is lower than the original baseline by 72 h, when the cells are still secreting substantial amounts of lysozyme. These data suggest that both transcriptional and post-transcriptional controls are operative in the control of lysozyme gene expression during the differentiation of HL-60 cells. They also imply that lysozyme secretion is not a necessary component in the macrophage-monocyte differentiation of these cells.

Evidence for two isozymes of leukocyte alkaline phosphatase in leukemic leukocytes

Leukocyte alkaline phosphatase (LAP) is a granulocyte enzyme whose level of expression is markedly altered in various disease states. We have characterized LAP from normal cells and leukemic cells with a high level of LAP activity in order to determine whether increased enzyme levels are caused by increased levels of the same enzyme or induction of a different alkaline phosphatase. Leukocyte alkaline phosphatase was purified from normal granulocytes and from leukemic cells of a patient with chronic granulocytic leukemia (CGL) in blast phase with an elevated LAP level. LAP was partially purified utilizing diethylaminoethyl (DEAE)-cellulose ion exchange chromatography, gel filtration, and preparative electrophoresis. The sample prepared from normal granulocytes contained a single protein with LAP activity having a molecular weight of 61,000 as determined by SDS gel electrophoresis. The sample from the CGL blast-phase cells, however, demonstrated two proteins with alkaline phosphatase activity, one with a molecular weight of 61,000 (LAPs) and one with a molecular weight of 45,000 (LAPf). Differential heat inactivation and distinct isoelectric points of the two isozymes suggest that they are different proteins. We interpret our data to suggest two closely related LAP alleles whose expression is controlled independently. This may represent either genetic heterogeneity or induction of "tumor marker" gene expression.

Purification of functional RNA from human granulocytes

The presence, in granulocytes, of high levels of nuclease activity makes it difficult to isolate intact RNA from these cells. We have developed a method that allows purification of functional RNA from normal granulocytes as determined by capability for reverse transcription and in vitro translation. We have shown that a considerable amount of ribonuclease activity remains in granulocyte lysates, even after the addition of heparin or vanadyl ribonucleoside complexes. RNA isolated from such lysates demonstrates only minimal binding to oligothymidylic-cellulose and does not serve as a template for reverse transcription or in vitro translation. However, the extraction of frozen granulocytes into phenol in the presence of both heparin and vanadyl ribonucleoside allows the purification of relatively large quantities of RNA, which serves as an excellent template for reverse transcription and in vitro translation. Purification of granulocyte RNA by this method will facilitate study of granulocyte gene expression.

Altered isozyme patterns of leucocyte alkaline phosphatase in disease states

Leucocyte alkaline phosphatase (LAP) is a granulocyte enzyme whose concentration varies in disease states. In order to determine whether the pattern of expression is altered in leukaemic granulocytes, we have analysed the LAP isozyme pattern of a series of normal subjects and patients with various haematological diseases. Electrophoretic patterns of partially purified LAP samples were determined by polyacrylamide gel electrophoresis in the presence of Triton X-100. These patterns were reproducible on repeated samples from the same patient. Presence of the LAPf and LAPs isozymes were determined after staining with the dye Fast Blue BB. Granulocytes were obtained from 15 normal subjects. Thirteen of these samples had only the LAPs isozyme. The other two had LAPs, plus a small amount (less than or equal to 10% of total) of LAPf activity. Eight patients with stable phase chronic myelogenous leukaemia (CML) had only small amounts of the normal LAPs isozyme and no evidence of LAPf . Of 11 patients with CGL who clinically had blast crisis. 10 had both LAPs and LAPf . The eleventh patient who was Ph1 negative had only LAPs. Three of five patients with polycythaemia vera had only the LAPs isozyme while two had both isozymes. Six patients with non-malignant leucocytosis had only LAPs. We interpret this data to indicate that the increased levels of LAP activity in some CGL blast crisis patients are primarily related to synthesis of the LAPf isozyme.

Leukocyte alkaline phosphatase: another organ-specific alkaline phosphatase

We have used enzyme specific inhibitors and heat inactivation to distinguish Leukocyte alkaline phosphate (LAP) from other organ-specific alkaline phosphatases as well as to compare LAP from normal granulocytes and leukemic cells with elevated LAP. The heat inactivation and inhibition curves of LAP are quite different from those of other organ-specific alkaline phosphatases. The inhibition curves and heat inactivation characteristics of LAP from normal granulocytes and that obtained from chronic granulocytic leukemia (CGL) blast phase cells with elevated LAP are identical. These data suggest that LAP is distinct from other organ-specific alkaline phosphatases, particularly placental alkaline phosphatase. We also conclude that the LAP present in cells with elevated levels is very similar or identical to that of normal granulocytes.

Measurement of carotid blood flow in man and its clinical application

With the use of a new ultrasonic volume flow meter (VFM), over 8000 measurements of common carotid blood flow were made in 120 normal control subjects and 550 patients with various neurological disease. The accuracy of the flow meter in measuring blood flow on an experimental model ranged from 93 to 97%. In normal subjects, common carotid blood flow varies with age. It increased from newborn to age 20 and gradually decreased thereafter. In normal healthy subjects, the flow varies within +/- 6.7% (2SD) at one sitting (intrasession) and +/- 21.2% (2SD) from week to week (intersession study). Carotid blood flow varies linearly with PaCO2 and increased markedly in response to endotracheal intubation. In healthy adults, the flow ratio between the two common carotid arteries is 1.07 +/- 0.052. This ratio increases in patients with transient ischemic attacks to 1.28 +/- 0.23 (p less than 0.05) and in patients with intracranial space occupying lesions to 1.46 +/- 0.39, (p less than 0.01). In 26 consecutive cases of carotid endarterectomies, the preoperative common carotid blood volume flow was 5.1 +/- 1.0 cc/sec. All cases preoperatively had at least 30% stenosis and ranged from 30 to 100% stenosis. The carotid blood volume was significantly increased post-operatively (p less than 0.001). The overall accuracy in detecting carotid and cerebral arterial disease is 89% with sensitivity of 96% and the specificity of 71%. Our clinical experience indicates that this device is not only a valuable noninvasive diagnostic tool for evaluation of carotid disease but also appears to be useful in assessing cerebral blood flow.

Examination of the mineral composition of the micelle of milk by gel filtration

When skim milk was passed through a column of Sephadex G-150 and eluted with distilled water, it separated into three peaks containing (I) "primary micelle", (II) "whey proteins", and (III) free electrolytes and other small molecules. "Primary micelle" which is composed of calcium caseinate and bound calcium phosphate was compared with whole micelle and colloidal phosphate-free micelle. The apparent lower calcium, magnesium, and phosphate contents, and absence of citrate in primary micelle were attributed to the removal of an adsorption layer from whole micelle. The qualitative and quantitative distribution of minerals in milk micelle is discussed and it appears that three zones could be distinguished: adsorbed double layer of ions, bound minerals, and casein counter-ions.