Rapid cellular translocation is related to close contacts formed between various cultured cells and their substrata

Interference-reflection microscopy combined with time-lapse cinemicrography was used to examine the relationship between cell-to-substratum contact patterns and the speeds of translocation for a variety of cell types. Rapid translocation of amphibian leukocytes (average speed = 9.0 micron/min), amphibian epidermal cells (7 micron/min) and teleost epidermal cells (7 micron/min) was found to correlate with patterns of broad grey close contacts. Similar contact patterns were found under freshly seeded (2 h) chick heart fibroblasts (moving 1-3 micron/min), the rapidly advancing (1-5 micron/min) margin of spreading human WI-38 fibroblasts, and isolated MDCK canine epithelial cells (0.5-1.0 micron/min). Conversely, numerous dark streaks of focal contact were found associated with the slow rate of translocation displayed by older cultures (72 h) of chick fibroblasts (less than 0.1 micron/min), well-spread WI-38 cells (less than or equal to 0.3 micron/min) and confluent MDCK cells (less than 0.01 micron/min). It is concluded that close contacts, but not focal contacts, are associated with rapid cellular translocation, and that the build-up of focal contacts is associated with reduced cellular translocation and maintenance of the spread cell shape.

Acute effects of hemodialysis on echographic-determined cardiac performance: improved contractility resulting from serum increased calcium with reduced potassium despite hypovolemic-reduced cardiac output

The hemodialysis session leads to reduction in circulating blood volume (TBV) and arterial pressure (BP) plus correction of electrolyte imbalance. The effect of these alterations on cardiac performance was evaluated in 18 patients with end-stage renal disease. Hemodialysis for 5 hours led to significant reduction (p less than 0.001) in weight TBV, and BP. Neither ejection fraction nor percentage fiber shortening was altered, whereas mean velocity of circumferential fiber shortening (mean VCF) and mean systolic ejection rate (MSER) were both significantly increased (1.17 +/- 0.20 to 1.38 +/- 0.28 circ/sec and 2.38 +/- 0.27 to 2.80 +/- 0.40 EDV/sec, respectively; p less than 0.001 for each). Since both venous return and systolic BP were decreased, increase in velocity of ventricular contraction implies enhancement of cardiac performance beyond what would be expected from alterations in ventricular filling and resistance to ejection. This enhancement is possibly related to concomitant reduction in serum potassium (p less than 0.001) and increase in serum calcium (p less than 0.005) achieved by hemodialysis.

Mechanism of retraction of the trailing edge during fibroblast movement

Retraction of the taut, trailing portion of a moving chick heart fibroblast in vitro is an abrupt dynamic process. Upon retraction, the fibroblast tail always ruptures, leaving a small amount of itself attached to the substratum by focal contacts. Time-lapse cinemicrography shows that retraction produces a sudden, massive movement of both surface and cytoplasmic material toward a cluster of focal contacts near the main body of the cell. The appearance of folds on the upper cell surface at this time and the absence of endocytotic vesicles are consistent with this forward movement. Retraction of the trailing edge, either occurring naturally or produced artificially with a microneedle, consists of an initial fast component followed and overlapped by a slow component. Upon artificial detachment in the presence of iodoacetate, dinitrophenol, and sodium fluoride, and at 4 degrees C, the slow component is strongly inhibited and the fast one only slightly inhibited. Moreover of the bundles of microfilaments oriented parallel to the long axis of the tail seen in TEM. Most of the birefringence is lost during the fast phase and the rest during the slow phase of retraction. Concurrently, the bundles of microfilaments disappear during the fast phase of retraction and are replaced by a microfilament meshwork. All of these results are consistent with the hypothesis that the initial fast component of retraction is a passive elastic recoil, associated with the oriented bundles of microfilaments, and that the slow component of retraction is an active contraction, associated with a meshwork of microfilaments.

Hematologic studies during isolated ultrafiltration

The effect of negative-pressure isolated ultrafiltration on leucocytes, platelets, and clotting factors was evaluated in maintenance hemodialysis patients. A significant decrease in the number of leucocytes was observed during the first 45 minutes of ultrafiltration. However, by one hour, leucocyte counts had returned to pre-ultrafiltration values. A slight, of haptoglobin, free hemoglobin, or fibrinogen after one hour of isolated ultrafiltration. Levels of fibrin degradation products and fibrin monomers similarly showed no change. Heparin administration alone had no effect on the above hematologic values. We suggest that isolated ultrafiltration, as clinically practised, has little acute effect on the coagulation system, and does not cause detectable hemolysis. The transient decrease in leucocyte count, and the modest fall in platelet count that were found are in keeping with changes previously reported to occur during hemodialysis.

Erratum

P2: a behavioural mutant of Dictyostelium discoideum

J. Cell. Sci. (1980). 43, 341–366.

The amoeba strain P2 was incorrectly identified as a mutant of the slime mould, Dictyostelium discoideum. I have been unable to repeat the reported observation of a karyotype of seven chromosomes, on which the original identification was based. Other properties, including the morphology of cysts and nucleoli, growth properties and cell shape, indicate that P2 is a hartmanellid amoeba.

I am indebted to Professor Kenneth Raper of the University of Wisconsin for pointing out the correct identification of this strain.

Effect of hemodialysis on blood volume distribution and cardiac output

Effects of hemodialysis on extracellular fluid volume distribution, left ventricular volumes, and cardiac output were determined in patients with end-stage renal disease (n = 19). Distribution of extracellular fluid loss from hemodialysis differed widely among patients, so that weight change correlated weakly with contraction of total blood volume (index of determination 29%, p less than 0.05). End-diastolic volume (EDV) decreased from 150 +/- 49 ml (mean +/- SD) to 118 +/- 42 ml, p less than 0.001; stroke volume (SV) decreased from 108 +/- 36 to 86 +/- 33 ml (p less than 0.001) without change in ejection fraction (from 0.73 +/- 0.09 to 0.74 +/- 0.11). A significant correlation was found between total blood volume (TBV) and EDV before (r = 0.66, p less than 0.005) and after dialysis (r = 0.61, p less than 0.001). The correlation between TBV and SV was highly significant before (r = 0.78, p less than 0.001) and after dialysis (r = 0.66, p less than 0.005), but there was no correlation between change in TBV and change in EDV or in SV. The ratio of EDV to TBV (EDV/TBV x 100) was reduced significantly from 3.49 +/- 0.92 to 3.06 +/- 0.97, p less than 0.001). There results suggest that, although intravascular volume was the major determinant of cardiac output in dialyzed patients, the postdialysis reduction in cardiac output might be related more to the relocation of blood volume than to the absolute degree of blood volume contraction.

Blood pressure response to hemodialysis

Blood pressure response to hemodialysis was investigated in 15 patients with end-stage kidney disease; mean arterial pressure was unchanged in five (Group 1) and reduced 10 mm Hg in 10 (Group 2). The two groups did not differ significantly with regard to either biochemical values or hemodynamic indices before dialysis, and both sustained comparable reduction in body weight, total blood volume, and cardiac output following dialysis. Heart rate remained unchanged in both. The only significant difference between the two was the response of total peripheral resistance (TPR) to fluid depletion. TPR rose adequately in Group 1 but was unchanged in Group 2 (7.5 +/- 2.2 (SE) vs 0.7 +/- 1.1 units, p less than 0.025) despite equal fall in cardiac output in both (881 +/- 212 vs 890 +/- 173 ml/m, p less than 0.10). Thus, differences in arterial pressure response to fluid loss by hemodialysis could be due to impaired autonomic control of resistance vessels; this abnormality might not be revealed by tests of baroreceptor activity that depend only on heart rate responses to blood pressure variations.

Hemodialysis ascites in anephric patients

Six maintenance hemodialysis patients are described in whom ascites was encountered at a time when they were anephric. No etiology for ascites could be found, and it was presumed that these patients were manifesting so-called "hemodialysis ascites". Our findings suggest that the use of bilateral nephrectomy in the treatment of hemodialysis ascites should be re-evaluated.

Fibronectin is not present in the focal adhesions formed between normal cultured fibroblasts and their substrata

Fibronectin is an extracellular matrix protein that has been implicated in the spreading and adhesion of cultured fibroblasts to their substrata. In this paper, double immunoelectron microscopic labeling experiments for fibronectin and for concanavalin A-binding proteins on the cell surface were carried out on ultrathin frozen sections of cultures of embryonic chicken heart fibroblasts. On cross sections though the focal adhesions of the cell to the substratum there was substantial labeling for concanavalin A-binding proteins but no detectable labeling for fibronectin, whereas both the binding proteins and fibronectin were extensively labeled elsewhere on the cell surface and substratum. These results demonstrate that fibronectin is not present within the sites of focal adhesions. Therefore, the functions of fibronectin in cell spreading and adhesion are not directly mediated through its binding at focal adhesion sites. An alternative model is presented which can account for such fibronectin functions.

Hydrostatic ultrafiltration during hemodialysis using decreasing sodium dialysate

Twelve patients underwent hemodialysis using dialysate containing 130 mEq/L sodium, and, on a separate occasion, dialysis using a dialysate of constantly decreasing sodium concentration (from 150 to 133 mEq/L). Hydrostatic ultra-filtration during dialysis was performed at a constant rate (900 ml/hr) during both treatments, and was continued until a substantial drop in mean arterial pressure (-15%) or symptoms were observed. A double-blind comparison of the two treatment modalities was thus achieved. At the end of ultrafiltration, significantly more fluid had been removed using decreasing sodium dialysate (2.9 +/- 0.3 kg) than when using the low-sodium dialysate (1.9 +/- 0.2 kg, P<0.001). Plasma sodium concentration at the end of ultrafiltration using decreasing sodium dialysate was not significantly different from the predialysis level. Hydrostatic ultrafiltration using a dialysate of decreasing sodium level may prove to be a useful means of removing excess fluid asymptomatically from dialysis patients.

Kinetics of peritoneal fluid absorption in patients with chronic renal failure

Previous measurements of fluid absorption from the peritoneal cavity were made after a single injection of a protein-bound marker by following changes in the concentration of the marker with time. Absorption of the marker substance itself had to be estimated. The present study measured absorption of peritoneal fluid by more direct methods. 1.5 to 2.1 L of 0.9% saline, along with 10 muCi of RISA were infused into the abdomens of nine chronic renal failure patients through peritoneal dialysis catheters. Initial paritoneal fluid volumes were determined by dilution. After 7 hr, a second dose of RISA (5 muCi) was infused, and volumes in the peritoneal cavity were again determinted by dilution of the increment dose. At 8 hr, an attempt was made to recover the RISA remaining in the peritoneal cavity by draining and repeatedly flushing that space. The amount of RISA recovered was used to calculate independently the amounts of RISA and fluid which had been absorbed during the 8 hr period. There was good agreement between peritoneal fluid volumes calculated at 7 and 8 hr by these and other techniques. By 7 hr, 23.8% +/- 10.9 S.D. of the initial peritoneal fluid volume ahd been absorbed. The amount of RISA absorbed during the same period was 17.3% +/- 4.9 of the initially administered dose. At 7 hr, only 23.7% +/- 6.3 of the absorbed RISA was in the plasma. The proposed techniques of volume measurement are valid and point to great variation among patients in the rate of fluid absorption from the peritoneal cavity.

Evidence from bioassay studies indicating a role for adenosine in cardiac ischemic and hypoxic dilation in the dog

Previous studies using bioassay demonstrated the presence of a vasoactive substance or substances in coronary sinus blood during myocardial reactive hyperemia which had, on bioassay, characteristics of adenosine and/or AMP. In the present studies, specific blockers were applied to an improved bioassay system to define more precisely the nature of the substance or substances and to determine whether it also appears during local cardiac hypoxia. In the anesthetized dog, coronary sinus blood was bioassayed in an isolated autologous kidney during reactive and hypoxic dilation. During reactive dilation, the bioassay kidney responded with a large resistance increase which was blocked by theophylline and adenosine deaminase and converted to a decrease by adenosine autoblockade. The same was true for hypoxic dilation, except in this instance, only adenosine deaminase reduced the response (40%). Theophylline and adenosine autoblockade eliminated responses of the bioassay organ to both exogenous adenosine and exogenous AMP, but adenosine deaminase was specific for adenosine. These results confirm that one or more vasoactive substances appear in sinus blood in vasoactive quantities during cardiac reactive dilation, and that the peak concentration correlates roughly with the peak flow. In addition, they show that this also is the case for hypoxic dilation. More importantly, they demonstrate that the substance almost certainly is adenosine in the case of reactive dilation, and that increased adenosine levels also are present during hypoxic dilation, but in addition, suggest that AMP sometimes appears in coronary sinus blood during severe cardiac hypoxia in the dog heart.

Induction of spreading during fibroblast movement

This paper describes the phenomenon of retraction-induced spreading of embryonic chick heart fibroblasts moving in culture. Measurable criteria of cell spreading (increase in area of the spreading lamella, and total spread area of the cell) are found to change predictably with retraction of a portion of the cell margin. Ruffling activity was found to increase. The leading lamella of a spread fibroblast ordinarily advances slowly, with an average area increase of approximately 21 mu2m/min. A 10- to 30-fold increase in spreading occurs within 8 s after onset of retraction at the trailing edge and then decreases slightly so that by 1 min the increase in spreading is five to tenfold. During this period, there is a linear relationship between area increase at the leading edge and area decrease at the trailing edge. During the next 10--15 min, spreading gradually decreases to normal. Although the relationship between area spreading and area retracting of fibroblasts at different phases of movement is not significantly linear, it is highly correlated (Table II). These results suggest that the rate of fibroblast spreading may be inversely related to the degree of spreading of the cell as a whole.

Treatment of dialysis elbow by simple aspiration

Olecranon bursitis with effusion in four maintenance hemodialysis patients was successfully treated with simple aspiration.

Treatment of metabolic alkalosis with peritoneal dialysis in a patient with renal failure

Peritoneal dialysis using a chloride-rich dialysate succeeded in correcting systemic metabolic alkalosis in a patient with renal failure. The present approach may have a place in the therapy of metabolic alkalosis.