Maleyl-BSA and fucoidan induce expression of a set of early proteins in murine mononuclear phagocytes

We examined the effect of maleyl-BSA on specific protein expression in murine peritoneal macrophages by radiolabeling treated macrophages with [35S]methionine followed by SDS-polyacrylamide gel electrophoresis. Such treatment induces the expression of a set of at least seven proteins (38, 42, 57, 65, 75, 80, and 85 kD). A similar set of proteins is also induced by treatment of macrophages with the algal polysaccharide fucoidan. The proteins resemble those induced in response to treatment of this same cell population with bacterial lipopolysaccharide (LPS), as judged by co-migration in both one- and two-dimensional electrophoresis. Two proteins induced by either LPS or maleyl-BSA (e.g., p57 and p85) show similar primary structure, as assessed by partial proteolytic peptide mapping confirming their identity. The induction of these proteins by maleyl-BSA is a transient phenomenon, being expressed as early as 1 hr after treatment and declining after 8 hr even in the continuous presence of the stimulus. The dose of maleyl-BSA required to induce the response varies to some extent with the protein in question, but agrees with the Kd for ligand-receptor binding. Chloroquine, which blocks the degradation of ligand, does not inhibit the induction of early protein synthesis. Whereas the induction of these proteins is blocked by inhibition of RNA synthesis with actinomycin D, the reversible inhibition of protein synthesis with cycloheximide during the induction phase does not prevent their expression. LPS, maleyl-BSA, and fucoidan previously have been shown to stimulate protease secretion and tumoricidal function in appropriately primed macrophages. The present findings now demonstrate that all three agents can also mediate the expression of early genes which may participate in the acquisition of functional competence.

Maleyl-BSA and fucoidan induce expression of a set of early proteins in murine mononuclear phagocytes

We examined the effect of maleyl-BSA on specific protein expression in murine peritoneal macrophages by radiolabeling treated macrophages with [35S]methionine followed by SDS-polyacrylamide gel electrophoresis. Such treatment induces the expression of a set of at least seven proteins (38, 42, 57, 65, 75, 80, and 85 kD). A similar set of proteins is also induced by treatment of macrophages with the algal polysaccharide fucoidan. The proteins resemble those induced in response to treatment of this same cell population with bacterial lipopolysaccharide (LPS), as judged by co-migration in both one- and two-dimensional electrophoresis. Two proteins induced by either LPS or maleyl-BSA (e.g., p57 and p85) show similar primary structure, as assessed by partial proteolytic peptide mapping confirming their identity. The induction of these proteins by maleyl-BSA is a transient phenomenon, being expressed as early as 1 hr after treatment and declining after 8 hr even in the continuous presence of the stimulus. The dose of maleyl-BSA required to induce the response varies to some extent with the protein in question, but agrees with the Kd for ligand-receptor binding. Chloroquine, which blocks the degradation of ligand, does not inhibit the induction of early protein synthesis. Whereas the induction of these proteins is blocked by inhibition of RNA synthesis with actinomycin D, the reversible inhibition of protein synthesis with cycloheximide during the induction phase does not prevent their expression. LPS, maleyl-BSA, and fucoidan previously have been shown to stimulate protease secretion and tumoricidal function in appropriately primed macrophages. The present findings now demonstrate that all three agents can also mediate the expression of early genes which may participate in the acquisition of functional competence.

Comparison of the infrared coagulator and the carbon dioxide laser in the removal of decorative tattoos

A comparative study of the removal of decorative tattoos by the infrared coagulator and the CO2 laser was performed. The comparison was made by following the parameters of length of healing time, postoperative pain, presence of residual pigment, and tendency for scarring. The results showed that the infrared coagulator had the advantages of a more rapid healing time, an easier-to-care-for treatment site, and an equivalent cosmetic result in comparison with the CO2 laser. The CO2 laser had the advantage of total pigment removal in a single treatment, whereas the infrared coagulator often left residual pigment.

Regulation of respiratory burst in murine peritoneal macrophages: differential sensitivity to phorbol diesters by macrophages in different states of functional activation

Activation of macrophages either in vivo or in vitro can modulate the capacity to generate and secrete reactive oxygen intermediates including H2O2 and O2-. Thus, the cellular and biochemical components requisite for execution of the respiratory burst must be regulated during the activation process. In the present report, we have examined murine peritoneal macrophages in different stages of activation for their sensitivity to stimulants of respiratory burst known to activate protein kinase c (i.e., phorbol dibutyrate or diacylglycerol). The results demonstrated that more highly activated macrophages showed, in addition to greater magnitude of H2O2 or O2- production, a two- to fourfold greater sensitivity to these stimuli. While more active macrophages also exhibited a higher rate of H2O2 secretion, the time at which secretion was measured did not account for or modulate the heightened sensitivity. The increased sensitivity to stimulation was dependent upon the stage of activation and not on the agent used to elicit the macrophages. Increased sensitivity of the more active macrophage populations was also seen when physiologic stimuli (i.e., insoluble immune complexes or unopsonized zymosan) were used. These findings indicate that macrophage activation for H2O2 secretion modulates the sensitivity to stimulation such that more H2O2 is produced in a shorter time and at a lower concentration of stimulus, thereby heightening the inflammatory response in several independent ways. Because all the stimuli employed in the present study have in common the ability to activate protein kinase c (either directly or indirectly), the data also suggest that this form of macrophage activation may involve, at least in part, modulation of the stimulus-response coupling mechanisms which utilize this enzyme.

Ethical problems in clinical research: the need for empirical studies of the clinical trials process

Society's demand for progress in medicine is expressed in the form of large sums of money poured into medical research by national governments and voluntary agencies. It is widely accepted within the medical profession that society has a right to expect continuing progress in medical practice and it has been argued that the doctor must therefore sometimes weigh society's interests against those of his individual patient. This essay discusses the origin of the concept of the societal obligation of the physician and the difficult position of the clinician-scientist who attempts to meet society's demands for progress while maintaining his traditional loyalty to the individual patient. Empirical studies which describe the impact of the clinical trials process on the practice of medicine are discussed and it is shown that the large scale clinical trials of today may influence aspects of medical practice far removed from the immediate problems which they are designed to study. It is concluded that further research is needed to study the process of clinical experimentation and its societal implications and that the debate must extend beyond the medical profession to involve the general public.

Regulation of the Fc-receptor-mediated respiratory burst: treatment of primed murine peritoneal macrophages with lipopolysaccharide selectively inhibits H2O2 secretion stimulated by immune complexes

The effect of bacterial lipopolysaccharide on the Fc-receptor-mediated respiratory burst in murine peritoneal macrophages has been examined. After treatment overnight with small quantities of LPS, macrophages exhibited dramatic diminution of their capacity to generate and secrete H2O2 when triggered with immune complexes. The effect of LPS treatment was dependent on the state of macrophage functional activation; only cells that were primed or fully activated in vivo or were treated with interferon-gamma in vitro were sensitive to this effect of LPS. The LPS-mediated loss of secretory function was both dose and time dependent and could be reproduced with the lipid A moiety of LPS. The effect was selective for H2O2 secretion triggered through the Fc receptor; the respiratory burst stimulated by phorbol diesters remained unaltered. Furthermore, LPS treatment did not alter either binding or ingestion of radiolabeled immune complexes in parallel with the change in H2O2 secretion, indicating that the suppressive effect was not due to compromised endocytic function. These results indicate that LPS treatment of primed macrophages regulates the function of Fc receptors and may uncouple receptor occupancy from generation and secretion of H2O2.

Regulation of the Fc-receptor-mediated respiratory burst: treatment of primed murine peritoneal macrophages with lipopolysaccharide selectively inhibits H2O2 secretion stimulated by immune complexes

The effect of bacterial lipopolysaccharide on the Fc-receptor-mediated respiratory burst in murine peritoneal macrophages has been examined. After treatment overnight with small quantities of LPS, macrophages exhibited dramatic diminution of their capacity to generate and secrete H2O2 when triggered with immune complexes. The effect of LPS treatment was dependent on the state of macrophage functional activation; only cells that were primed or fully activated in vivo or were treated with interferon-gamma in vitro were sensitive to this effect of LPS. The LPS-mediated loss of secretory function was both dose and time dependent and could be reproduced with the lipid A moiety of LPS. The effect was selective for H2O2 secretion triggered through the Fc receptor; the respiratory burst stimulated by phorbol diesters remained unaltered. Furthermore, LPS treatment did not alter either binding or ingestion of radiolabeled immune complexes in parallel with the change in H2O2 secretion, indicating that the suppressive effect was not due to compromised endocytic function. These results indicate that LPS treatment of primed macrophages regulates the function of Fc receptors and may uncouple receptor occupancy from generation and secretion of H2O2.

Carbon dioxide laser treatment of porokeratosis of Mibelli

Porokeratosis of Mibelli, a disorder of keratinization, has in the past been difficult to treat, especially in its more extensive form. The carbon dioxide laser was used in the treatment of a patient with this disorder. The response was very favorable. Microscopic pathological investigation after treatment revealed no residual evidence of porokeratosis in the areas treated with the carbon dioxide laser. Thus, obliteration of this disease process using the carbon dioxide laser shows potential for future use.

Fc-receptor mediated protein phosphorylation in murine peritoneal macrophages

The effect of Fc receptor engagement on protein phosphorylation in murine peritoneal macrophages has been investigated. Treatment of macrophage cultures with insoluble immune complexes resulted in enhanced phosphorylation of six proteins at 73, 66, 53, 37, 31 and 25 kD. Comparison of the protein phosphorylation patterns induced by immune complexes with those induced by agents which mimic the actions of well known intracellular second messengers (i.e., A23187, dibutyryl cAMP, or phorbol myristate acetate) revealed substantial similarity between Fc receptor induced events and those induced in response to phorbol diesters. There were, however, two phosphorylated proteins which were only seen following stimulation with immune complexes. Thus, more than one kind of protein kinase activity appears to be involved in Fc receptor mediated stimulation of macrophage function.

Replication in Plastic of Three-Dimensional Fossils Preserved in Indurated Clastic Sedimentary Rocks

A new technique for replicating in plastic the fossils preserved in clastic rocks should now make available reliable morphologic and frequency data, comparable in quality to those derived from acid-prepared silicified faunas, for a major segment of the fossil record. The technique involves three steps: the dissolution of carbonate in fossiliferous rocks with hydrochloric acid, impregnation of resulting voids with liquid plastic, and dissolution of the rock matrix with hydrofluoric acid, leaving a concentrate of plastic-replaced fossils.

Recovery of proximal tubular function from ischemic injury

Fluid (sodium) reabsorption, total glucose efflux, and reabsorption of angiotensin II and insulin from the proximal convoluted tubule were studied in rats by in vivo microperfusion. After 35 min of total renal artery occlusion, function was assessed at two intervals, 0-1 h (early recovery, ER) and 2-4 h (late recovery, LR). Light and electron microscopic evaluation showed 60-75% loss of proximal convoluted tubule brush border membrane in ER and nearly complete restoration of brush border in LR. No other structural abnormalities were evident. Renal blood flow was unchanged from control during both ER and LR. During ER, fluid reabsorption was reduced to 29.8 +/- 5.2%, and total glucose efflux, at normal tubule loads, to 73.9 +/- 5.5% of control. However, angiotensin II and insulin reabsorption were unchanged. In LR, fluid reabsorption remained significantly reduced at 54.3 +/- 8.1% of control. Total glucose efflux from the proximal tubule was normal in LR at glucose loads of up to 400 pmol X min-1, but was significantly reduced at higher loads. Passive glucose efflux, measured in the presence of 10(-4)M phloridzin, was not altered by ischemia. Brief ischemia results in significant alterations in proximal tubular reabsorption of sodium and glucose, which correlate with a substantial loss of brush border during ER. However, despite restoration of cell morphology to normal in LR, transport defects for both sodium and glucose persist.

Multiple drug resistance in the fission yeast Schizosaccharomyces pombe: evidence for the existence of pleiotropic mutations affecting dependent transport systems

The uptake of L-tyrosine into wild type and antibiotic resistant strains of Schizosaccharomyces pombe requires an energy source, is initially linear with respect to time, is inhibited by 2,4-dinitrophenol and sodium azide and is saturable. However the initial uptake rates and the amount of L-tyrosine accummulated by antibiotic resistant strains are much less than wild type. Comparison of the kinetic constants of uptake shows that mutant strains have a reduced maximum velocity of uptake compared to wild type and a larger Km. Since the three mutant strains possess a permeability barrier to L-tyrosine as well as being drug resistant this is an indication that antibiotic resistance may be caused by a decrease in plasma membrane permeability.

Prostaglandins mediate the vasodilatory effect of mannitol in the hypoperfused rat kidney

We have previously reported that mannitol strikingly increases blood flow to rat kidneys hypoperfused at 35-40mm Hg. This vasodilator effect is not due to volume expansion or alterations in plasma osmolality. We have tested the hypothesis that the vasodilatory effect of mannitol in the ischemic rat kidney is mediated by one of the vasoactive renal hormone systems: renin-angiotension, kallikrein-kinin, or prostaglandins. Rats were infused with 5% mannitol in 0.9% saline to 3-5% of body weight. In agreement with our previous studies, RBF increased 1.3 +/- 0.1 ml/min despite maintenance of perfusion pressure at 35-40 mm Hg. The cyclooxygenase inhibitors, meclofenamate and indomethacin had no effect on renal blood flow (RBF) in hypoperfused kidneys. However, in rats pretreated with these inhibitors, expansion with mannitol increased RBF by only 0.37 +/- 0.02 ml/min, 28% of the response in the untreated group (p less than 0.001). Infusion of prostacyclin (PGI2) into the renal artery during reduced perfusion resulted in an increase in RBF of 1.0 +/- 0.1 ml/min. Subsequent expansion with mannitol increased RBF by only 0.5 +/- 0.1 ml/min more, less than one-half of the effect of mannitol in a concurrent group of rats not treated with PGI2. Unlike PGI2 prostaglandin E2 had only a minimal vasodilator effect during hyperperfusion. Imidazole, an inhibitor of thromboxane synthesis, did not alter RBF or renal vascular resistance during hypoperfusion. Treatment of rats during hypoperfusion. with the angiotensin-converting enzyme (kininase II) inhibitor teprotide increased RBF by 1.1 +/- 0.3 ml/min. However, teprotide did not alter the vascular response to mannitol: RBF increased 1.2 +/- 0.1 ml/min more when mannitol was infused into teprotide-treated rats. The renal vascular response to mannitol was not altered by treatment with aprotinin, an inhibitor of the kallikrein-kinin system. Aprotinin was ineffective whether given before or after the vascular response to mannitol was established. We conclude that the vasodilator response to mannitol in the ischemic rat kidney is mediated in large part by increased prostaglandin (PGI2) activity. The failure of converting enzyme inhibition and aprotinin to block the vasodilator response to mannitol is evidence against a role for the renin-angiotension or kallikreinkinin systems in mediating the vasodilator response.

Influence of auditory fatigue on masked speech intelligibility

Intelligibility of PB word lists embedded in simultaneous masking noise was evaluated before and after fatiguing-noise exposure. Intelligibility was determined by observing the number of words correctly repeated during a shadowing task. Both the speech signal and the masking noise were filtered to a 2825-3185 Hz band. Masking-noise levels were varied from 0- 90-dB SL. Fatique was produced by a 1500-3000-Hz octave band of noise at 115 dB (re 20 muPa) presented continuously for 5 min. The results of three experiments indicated that speech intelligibility was reduced when the speech was presented against a background of silence but that the fatiguing-noise exposure had no effect on intelligibility when the speech was made more intense and embedded in masking noise of 40-90-dB SL. These observations are interpreted by considering the recruitment produced by fatique and masking noise.

Effect of volume expansion on hemodynamics of the hypoperfused rat kidney

The hemodynamics of the rat kidney were studied during reduction of renal arterial pressure to 35-40 mm Hg (H), and after volume expansion at that pressure with 0.9% NaCl (IS), 1.7% NaCl (HS), 5% mannitol in 0.9% NaCl (MS), 5% mannitol in water (MW), or 50 mM mannitol + 125 mM NaCl. During H, left renal blood flow (RBF) was 0.8+/-0.1 ml/min. Expansion with IS did not alter RBF, but expansion with HS, MS, MW, and 50 + 125 mM NaCl elevated RBF to 200-250% of hypoperfusion values. Glomerular capillary pressure rose significantly from 15.7+/-0.7 mm Hg during H to 22.3+/-1.1, 24.4+/-0.7, and 26.6+/-0.7 mm Hg following expansion with HS, MS, or MW, respectively. Efferent arteriolar pressure also rose significantly to 6.9+/-0.5, 9.7+/-0.8, and 9.5+/-0.9 mm Hg, respectively. Preglomerular resistance fell to 18-24% of H values, and postglomerular resistance fell to 58-74% of H values after expansion with HS, MS, or MW. Glomerular filtration (GFR) could not be detected during H or after IS expansion. HS and mannitol-containing solutions restored GFR to 0.10+/-0.02-0.15+/-0.02 ml/min, and single nephron glomerular filtration to 6-12 nl/min. Papaverine, acetylcholine, and kinins had no effect on RBF or GFR at a perfusion pressure of 35-40 mm Hg. We conclude that mannitol and HS have the capacity to augment RBF during hypoperfusion by reducing arteriolar resistance. The mechanism of the rise in RBF is uncertain; it may be due to changes in effective osmolality of the extracellular fluid or to a direct action of mannitol on vascular smooth muscle. Other potent vasodilators were ineffective during hypoperfusion. Restoration of GFR occurs as a result of the combined effects of augmented RBF and elevated net filtration pressure.

Effect of chronic potassium loading on potassium secretion by the pars recta or descending limb of the juxtamedullary nephron in the rat

Recently we demonstrated potassium secretion by the pars recta or by the descending limb of the juxtamedullary nephron. The purpose of this present investigation is to study the effect of a chronic high-potassium intake on this phenomenon. Fractional reabsorption of water and sodium by the juxtamedullary proximal nephron was decreased when compared to that in normal hydropenic rats. There was a striking increase in the fraction of filtered potassium at the end of the juxtamedullary descending limb from 94+/11% to 180+/18%, which was principally a result of enhanced potassium secretion. When the concentration of potassium in the collecting tubule fluid of potassium-loaded rats was reduced after the administration of amiloride, a sharp fall was observed in the amount of potassium which reached the end of the descending limb (64+/8%). A direct correlation was observed between the fraction of filtered potassium at the descending limb and the potassium concentration in the final urine (P less than 0.001). The findings suggest that potassium, like urea, normally undergoes medullary recycling, which is enhanced by chronic potassium loading.

Evidence for a concentration gradient favoring outward movement of sodium from the thin loop of Henle

Recent models of the urinary concentrating mechanism have postulated that urea in the medullary interstitium creates a transtubular concentration gradient for sodium between fluid at the end of the descending limb of Henle's loop and the medullary interstitium, favoring the passive outward movement of sodium from Henle's thin ascending limb. These experiments were designed to determine whether such a gradient normally exists. Young nondiuretic Munich-Wistar rats were prepared for micropuncture of the exposed left renal papilla. Samples of loop of Henle fluid and vasa recta plasma (assumed to reflect the composition of interstitial fluid) were obtained from adjacent sites. Loop fluid values in 21 comparisons from 18 rats (mean +/- SE) were: sodium 344 +/- 12 meq/liter; potassium, 26 +/- 2 meq/liter; osmolality, 938 +/- 37 mosmol/kg H23. Vasa recta plasma values (in corresponding units of measurement) were: sodium, 284 +/- 11; potassium, 34 +/- 2; osmolality, 935 +/- 34. Mean values of paired differences (loop fluid minus vasa recta plasma) were: delta sodium, 60 +/- 11.1 (P less than 0.001); delta potassium, -8.0 +/- 2.1 (P less than 0.001); delta osmolality, 4 +/- 16 (NS). Corrected for plasma water, the loop fluid minus vasa recta differences (in milliequivalents per kilogram H2O) were: delta sodium, 40 +/- 11.4 (P less than 0.005); delta potassium, -9.7 +/- 1.9 (P less than 0.001). We interpret these findings to indicate that in the papilla of nondiuretic rats, a significant difference in sodium concentration exists across the thin loop of Henle favoring outward movement of sodium, which confirms a key requirement of the passive models. A concentration difference for potassium in the reverse direction was also observed.

An examination of transcapillary water flux in renal inner medulla

We recently demonstrated that net fluid uptake occurs in the capillary system of the inner medulla. To define the site of fluid uptake, the concentration of protein was determined in plasma from descending vasa recta at the base and tip of the exposed papilla in Munich-Wister rats. The vasa recta plasma-to-arterial plasma protein concentration ratio (VR/P) was 1.43 +/- 0.09 at the base and 1.66 +/- 0.09 at the tip. These results, which indicate fluid loss from the descending vasa recta, are difficult to explain on the basic of hydraulic and oncotic forces alone. The osmolality of the contents of descending vasa recta increased between base and tip (delta = 72 +/- 30 mosmol/kg H2O). If the increase in osmolality of plasma in descending vasa recta lags behind that of the adjacent medullary interstitium, a transcapillary osmotic driving force exists favoring water loss from descending vessels. It is concluded that fluid uptake by the inner medullary circulation occurs beyond descending vasa recta in interconnecting capillaries or ascending vasa recta. In our view the most likely interpretation of these results is that fluid movement across vasa recta in the inner medulla is influenced by three forces: those owing to transcapillary differences in osmotic, oncotic, and hydraulic pressures.