The intestinal absorption of sodium taurocholate was studied in the near-term fetal and neonatal dog. Absorption rates were measured in vivo in isolated loops of fetal jejunum and ileum. Absorption was also measured in vitro in everted sacs and rings of fetal and neonatal jejunum and ileum. The maximal rates of taurocholate absorption observed after instillation of 1 micronmol taurocholate into closed segments of fetal jejunum and ileum with intact blood supply were not significantly different (P less than 0.2), and equalled 0.282+/-0.026 (mean+/-SEM) and 0.347+/-0.051 micronmol/h per 10-cm segment length jejunum and ileum, respectively. Similarly, the rates of absorption from open segments of jejunum and ileum perfused with 0.4 and 1.0 mM taurocholate were nearly identical (0.232+/-0.040 and 0.255+/-0.039, respectively at 0.4 mM, and 0.470+/-0.065 and 0.431+/-0.013, respectively at 1.0 mm) (P greater than 0.2). At perfusate concentrations of 4.0 mM, moreoever, jejunal absorption exceeded ileal absorption (1.490+/-0.140 and 0.922+/-0.200, respectively (P less than 0.05). As expected, concentration of taurocholate by the mucosa was readily demonstrated in adult ileal, but not in adult jejunal everted rings. In contrast, there were no significant differences in mucosal uptake of taurocholate by fetal jejunal and ileal rings. Fetal ileal mucosal concentrations were not significantly above those in the incubation medium after 1-h exposure of the mucosa to 0.003, 0.03, and 0.3 mM taurocholate. Uptake was proportional to incubation medium concentration over the full range of values. This was also true of tissues from 1-wk-old neonates. However, by 2 wk of age, ileal mucosal concentration of taurocholate was evident and adult levels were attained by 5 wk of age. It is concluded that taurocholate is absorbed by the fetal gut and that ileal absorption is no more efficient than jejunal absorption. Although active glucose transport was demonstrable in both jejunum and ileum, it was not possible to demonstrate an ileal mechanism for active transport of taurocholate in the fetus. Active ileal transport was not demonstrable in the newborn until at least 2 wk after birth.
R Lester, R A Smallwood, J M Little, A S Brown, G J Piasecki, B T Jackson
The effects of chemotherapy, with nitrosoureas or dimethyl-triazeno-imidazole-carboxamide (DTIC), or immunotherapy with Bacillus Calmette-Guérin (BCG), on cell-mediated immunity (CMI), and serum blocking factor (BF) to melanoma cells were studied in 23 patients. Studies were performed with autologous or allogenic melanoma target cells obtained from recent biopsy, in 16 mm diameter plastic wells. Assays for lymphocyte-mediated cytotoxicity and BF were performed at weekly intervals over the course of 3-4 mo, with some studies extending beyond 3 yr. The specificity of cytotoxicity was good with these methods. Nine patients given nitrosoureas, predominantly methyl-chloroethyl-cyclohexyl-nitrosourea, showed a transient decline in CMI from 42.2 to 14% 3 wk after administration of a single dose of the agent, with a rapid recovery within 1 week. 10 patients given 5-day courses of DTIC at 3-wk intervals showed no decline in CMI after two courses, and 7 of the 10 had no decline even after three courses. Three of the four patients who achieved a remission lost BF previously present: BF reappeared in both patients studied during a subsequent relapse. BCG intradermally or intralesionally elevated CMI within 2 mo after initiation of therapy, but despite continuation of the injections CMI returned to base line in all but two of the nine patients studied. These results indicate that chemotherapy for melanoma with nitrosoureas or DTIC at these schedules is not profoundly immunosuppressive towards tumor-specific immunity, as measured by our procedures. Putative immunotherapy with BCG at these schedules was likewise only transiently stimulatory.
M S Mitchell, M B Mokyr, J M Davis
Paired samples of an intact rabbit aortic intima-media preparation were incubated for short periods under aerobic or anoxic conditions in Krebsbicarbonate buffer containing 6% albumin and 5 mM glucose. During aerobic incubation for as long as 1 h the preparation retained an electron microscopic (EM) appearance similar to that of tissue fixed in situ, and scanning EM confirmed the presence of an uninterrupted endothelial surface. After 2.5 min of anoxia there was widespread endothelial swelling, but the alterations in the EM appearance of these cells were not striking and did not progress during a subsequent 30 min aerobic incubation in fresh medium. After 10 min of anoxia there were marked and widespread alterations in endothelial cell structure, including loss of cell integrity, and numerous discrete interruptions in the endothelium were consistently observed on both transmission and scanning EM. After a subsequent 30 min aerobic incubation in fresh buffer, a major fraction of the luminal surface was denuded of endothelium. The aortic vascular smooth muscle cells did not exhibit evidence of irreversible anoxic injury after 2.5 or 10 min of anoxia or after subsequent aerobic incubation for 30 min. Exposure to anoxia for 10 min induced persistent alterations in the composite metabolism of the preparation during subsequent aerobic incubation in fresh medium; O2 uptake was reduced, and the fraction of the glucose uptake that was accounted for by lactate production increased approximately 100%.
Anthony D. Morrison, Lelio Orci, Leonard Berwick, Alain Perrelet, Albert I. Winegrad
To test the hypothesis that carbon monoxide transfer across the placenta is, in part, a facilitated process, we have looked for evidence of saturation kinetics for carbon monoxide. In eight pregnant ewes, fetal to maternal carbon monoxide transfer was examined in a preparation in which the fetal side of the placenta was perfused with blood. The carboxyhemoglobin concentrations on the fetal side of the placenta were varied from 4.8 to 70% in 23 measurements. At increased carbon monoxide tensions, the transfer from fetus to mother always decreased. The slope of log rate of carbon monoxide transfer vs. log partial pressure gradient across the placenta was significantly different from 1. Placental membrane diffusing capacity was calculated separately from total placental diffusing capacity which includes hemoglobin reaction rates and erythrocyte membrane diffusion. Placental membrane diffusing capacity decreased at increased carbon monoxide tensions. Placental permeability for urea did not change with increasing carbon monoxide tensions. These results are consistent with the hypothesis that carbon monoxide diffusion in the placenta is, in part, carrier mediated.
J M Bissonnette, W K Wickham, W H Drummond
The physical states and phase behavior of the lipids of the spleen, liver, and splenic artery from a 38-yr-old man with Tangier disease were studied. Many intracellular lipid droplets in the smectic liquid crystalline state were identified by polarizing microscopy in macrophages in both the spleen and liver, but not in the splenic artery. The droplets within individual cells melted sharply over a narrow temperature range, indicating a uniform lipid composition of the droplets of each cell. However different cells melted over a wide range, 20-53°C indicating heterogeneity of lipid droplet composition between cells. Furthermore, most of the cells (81%) had droplets in the liquid crystalline state at 37°C. X-ray diffraction studies of splenic tissue at 37°C revealed a diffraction pattern typical of cholesterol esters in the smectic liquid crystalline state. Differential scanning calorimetry of spleen showed a broad reversible transition from 29-52°C, with a maximum mean transition temperature at 42°C, correlating closely with the polarizing microscopy observations. The enthalpy of the transition, 0.86±0.07 cal/g of cholesterol ester, was quantitatively similar to that of the liquid crystalline to liquid transition of pure cholesterol esters indicating that nearly all of the cholesterol esters in the tissue were free to undergo the smectic-isotropic phase transition.
Saul S. Katz, Donald M. Small, Jacob G. Brook, Robert S. Lees
The effects of acute bilateral ureteral obstruction (BUO) of 18-h duration on deep nephron and collecting duct function were studied by micropuncture in 11 weanling rats. After release of BUO glomerular filtration rate was reduced (178±15 vs. 1,343±119 μl/min per g kidney weight in shams), while urine flow was increased averaging 17.5±1.3 vs. 6.8±0.72 μl/min per g kidney weight in controls. There was a marked increase in the absolute and fractional excretion of Na. Single nephron glomerular filtration rate of deep nephrons was reduced in the BUO group, mean 19.4±3.5 vs. 77.0±7.7 nl/min per g kidney weight in shams. Single nephron glomerular filtration rate of superficial nephrons fell to the same extent after relief of BUO. Mean tubular fluid to plasma inulin ratio of fluid from Henle's loop was 2.46±0.20 after relief of BUO vs. 8.23±0.85 in shams. This suggested a reduction in the reabsorption of Na and water before the bend of the loop of Henle, most likely in both the proximal tubule and descending limb. Fluid osmolality was depressed due to a decline in both Na and nonelectrolyte solute content. After release of BUO the percentage of filtered water remaining in the collecting duct (CD) at the base of the papilla was greater than in controls (13.3±2.0 and 1.72±0.01%, respectively) but fell significantly by the tip of the papilla to 7.92±1.12 vs. 1.17±0.02% in controls. These results indicate that water was reabsorbed along the terminal CD after relief of ureteral obstruction. In fact, a greater fraction was reabsorbed in this segment after release of BUO (5.37±1.58%) than after sham operation (0.55±0.15%). Similar changes were seen in Na excretion. Thus alterations in deep nephron function appear to contribute to the natriuresis and diuresis which follow release of BUO while terminal CD function in this model appears intact.
John Buerkert, Mary Head, Saulo Klahr
Antibodies to native DNA and to polyadenylic acid (Poly A) occur spontaneously and undergo a regulated switch from IgM to IgG during the course of autoimmune disease in NZB/NZW F1 (B/W) mice. B/W females have higher titers and earlier commitment to 7S antibodies to DNA and Poly A, whereas B/W males bind DNA and Poly A primarily by 19S antibodies. We have performed castration experiments to determine the effects of sex hormones on this switch from IgM to IgG.
Jirayr R. Roubinian, Ruben Papoian, Norman Talal
Homogentisic acid inhibits the in vitro activity of chick embryo lysyl hydroxylase, a microsomal enzyme which catalyzes the transformation of certain lysyl residues in collagen to hydroxylysine. Chick embryo lysyl hydroxylase activity was measured as specific tritium release as tritium water from a [4,5-3H]lysine-labeled unhydroxylated collagen substrate prepared from chick calvaria. Kinetic studies revealed a linear, noncompetitive type of inhibition with respect to collagen substrate with a Ki of 120-180 μM. The inhibition by homogentisic acid was reversible in that enzyme activity could be restored after dialysis of preincubated mixtures of homogentisic acid with enzyme or substrate. The inhibition by homogentisic acid was competitive with respect to ascorbic acid, and the addition of reducing agents, such as ascorbic acid or 1,4-dithiothreitol, protected lysyl hydroxylase activity from homogentisic acid inhibition.
John C. Murray, Kenneth A. Lindberg, Sheldon R. Pinnell
Increased bronchial sensitivity to inhaled histamine in asthma is well known. The mechanism of this increased bronchial sensitivity is not known nor has it been demonstrated that isolated cells respond abnormally to histamine. Polymorpho-nuclear leukocytes (PMNs) provide a homogeneous cell population to study agonist response. Release of granulocyte lysosomal enzymes is inhibited by agonists increasing the PMN cyclic AMP concentration. The release of the lysosomal enzyme beta glucuronidase by serum-activated particles of zymosan was similar in PMNs isolated from normal and asthma subjects. Histamine (100-0.01 μM) inhibited enzyme release. Except at the maximal concentration of histamine (100 μM), the response to histamine was decreased in asthma. The inhibition of enzyme release paralleled an increase in intracellular PMN cyclic AMP. In asthma, the cyclic AMP response to histamine was reduced. The H2 antihistamine metiamide blocked histamine inhibition of lysosomal enzyme release and the increase in cyclic AMP. The effect was maximal at concentrations equimolar to those of histamine. The H1 antihistamine chlorpheniramine had no effect on histamine inhibition of granulocyte lysosomal enzyme release. A decrease in the inhibition of the release of the inflammatory lysosomal enzymes from granulocytes in asthma may contribute to an enhanced bronchial inflammatory reaction.
William W. Busse, Jeffrey Sosman
The ability of polymorphonuclear leukocytes (PMN) to produce H2O2 in response to phagocytic stimulation was examined cytochemically using leukocytes from normal individuals and patients with chronic granulomatous disease (CGD). Normal PMN oxidized diaminobenzidine within the phagocytic vacuole by a reaction dependent upon endogenous H2O2 and myeloperoxidase. CGD PMN failed to oxidize diaminobenzidine, which is consistent with the biochemical data showing a lack of H2O2-generating capacity. A plasma membrane enzyme (oxidase) activated by phagocytosis is capable of H2O2 production in PMN. The localization of this oxidase activity was explored in CGD PMN using a cytochemical technique specific for H2O2. The enzyme activity is stimulated by exogenous NADH, but not NADPH. Reaction product formation, indicative of activity of the oxidase, is dependent upon precipitation of cerium ions by the enzymatically generated H2O2. The advantage of this approach is that enzyme activity of individual cells can be assessed, allowing determination of numbers of reactive cells in the population and their relative degrees of reactivity. NADH oxidase was found to be active both on the plasma membrane and within the phagocytic vacuoles of control PMN, whereas those cells from three CGD patients showed greatly reduced activity in both these sites. Assessment of the reactivity of individual cells showed the number of cells with oxidase activity in CGD to be significantly reduced when compared to control values. Additionally, of those cells that do react, a higher percentage of them are only weakly reactive. Omission of NADH from the incubation medium reduced the percentage of control cells showing enzyme activity but had no effect on CGD PMN, implying that the enzyme is not saturated with substrate in control cells, but in CGD the diminished enzyme is fully saturated. The defect may lie in the fact that in CGD patients there are fewer cells capable of peroxide generation, and a majority of these reactive cells produce only reduced amounts of this bactericidal agent.
Richard T. Briggs, Manfred L. Karnovsky, Morris J. Karnovsky
This study was designed to examine whether prostaglandin E2 can directly affect sodium transport across isolated perfused rabbit renal collecting tubules. Changes in transepithelial potential and isotopic sodium fluxes in response to peritubular prostaglandin E2 were measured. In addition, changes in transepithelial potential of the outer medullary collecting tubule in response to prostaglandin E2 were also measured. With few exceptions, all rabbits received 5 mg/day desoxycorticosterone acetate for 4-11 days before experimentation. The results of the experiments show that: (a) prostaglandin E2 inhibits the negative transepithelial potential in the cortical collecting tubule as well as the outer medullary collecting tubule; (b) prostaglandin E2 inhibits net sodium transport out of the lumen by inhibiting efflux while backflux is unaffected; (c) prostaglandin E2 produces this inhibition within 15 min, and the effects are dose dependent and reversible. These results suggest that prostaglandin E2 may modulate sodium transport in vivo and may contribute to the final regulation of sodium excretion.
J B Stokes, J P Kokko
Previous studies have suggested that there is an overproduction of triiodothyronine (T3) relative to thyroxine (T4) in patients with thyrotoxicosis associated with Graves' disease. To evaluate whether or not an increased ratio of T3 to T4 in thyroidal secretion could be contributing to this relative T3 hyperproduction, T3, T4, and iodine were measured in thyroglobulin (Tg) from controls and patients with Graves' disease who had been treated either with propranolol only or with antithyroid drugs plus iodide before surgery. To avoid possible artifacts associated with pulse labeling and chromatography, T3 and T4 were determined by radioimmunoassay of Pronase hydrolysates of purified Tg. Results of analyses of Tg from six control patients and seven with Graves' disease, not receiving thiourea drugs or iodide, showed that the iodine content of Graves' disease Tg was not different from normal. Both contained 3.4 residues of T4/molecule Tg, but there was 0.39±0.08 (mean±SD) residue of T3/molecule Tg in Graves' Tg as opposed to 0.23±0.07 residue T3 molecule Tg in controls matched for iodine content (P < 0.01). This difference resulted in a significantly lower T4/T3 molar ratio (9±2) in Graves' Tg as opposed to control (15±2, P < 0.001). In Tg from patients with treated Graves' disease, iodine, T3, and T4 were reduced, but the reduction in the latter was more substantial, resulting in a T4/T3 molar ratio of 3.4±1. Fractionation of Tg from all groups by RbCl density gradient ultracentrifugation indicated that at physiological levels of Tg iodination, the molar ratio of T3/Tg was consistently higher in Graves' disease. The specific mechanism for this difference is not known, but it is not due to iodine deficiency. If T3 and T4 are secreted in this altered ratio in patients with Graves' disease, the magnitude of the difference could explain the relative T3 hyperproduction which is characteristic of this state.
M. Izumi, P. Reed Larsen
Calcium and sodium permeability of human reticulocytes have been studied and compared to mature erythrocytes. Mature erythrocytes had extremely low Ca2+ permeability which was less than 0.1% of values published for squid axon or HeLa cells. Calcium entry was markedly increased in reticulocyte-rich suspensions and the uptake was linearly related to the percentage of reticulocytes present. The data suggest that reticulocytes are 43-fold more permeable to Ca2+ than mature cells although their Ca2+ concentration is not increased. Sodium influx into reticulocyte-rich suspensions was also increased in direct proportion to the percent of reticulocytes present. Reticulocytes are sixfold more permeable to Na+ than mature cells so the ratio of Ca2+:Na+ permeability falls by sevenfold as the reticulocyte changes to an erythrocyte. [3H]Ouabain binding was increased in reticulocyte-rich cell suspensions and the correlation suggested a value of about 4,000 sites per reticulocyte compared with 362+/-69 per mature cell. Maturation of the human reticulocyte produces disproportionate changes in cation permeability and in particular a selective loss of Ca2+ permeability.
J S Wiley, C C Shaller
The reduced capacity of patients with multiple myeloma to respond to antigen challenge is well recognized. Response to antigen involves antigen recognition, cell proliferation, and synthesis and secretion of antibody. This study examines this sequence of events in peripheral blood lymphocytes from untreated and treated patients with myeloma, from individuals with benign monoclonal gammopathy, and from normal healthy donors. Antigen-binding capacity was assessed by testing the ability of lymphocytes to bind radio-labeled pneumococcal polysaccharide, tetanus toxoid, or diptheria toxin. The in vitro proliferative response to these antigens as well as to pokeweed mitogen and streptokinase-streptodornase was evaluated. The secretion of immunoglobulin in response to pneumococcal polysaccharide, tetanus toxoid, and pokeweed mitogen by 2-4 × 106 lymphocytes in 7-day cultures was determined. The effects of coculture of myeloma peripheral blood lymphocytes and normal peripheral blood lymphocytes on immunoglobulin production and mixed leukocyte reactions were explored. All myeloma patients had normal numbers (3-8/5,000 cells) of antigen-binding cells. However, most showed a diminished antigen-induced blast transformation as measured by uptake of [125I]5-iodo-2′-deoxyuridine in culture. Immunoglobulin production in response to specific antigen in myeloma lymphocytes was 30-80% less than in normal lymphocytes. Immunoglobulin synthesis and mixed leukocyte responses by normal peripheral blood lymphocytes could be suppressed by myeloma lymphocytes. Multiple suppressor populations were present. Thus, the immune defect in myeloma is beyond the antigen recognition step and involves both the proliferation of antigen-sensitive cells and immunoglobulin production. Further suppressive effects are imposed on normal cells, implying defects in immunoregulation in this disease.
Teresa Paglieroni, Malcolm R. MacKenzie
The presence of circulating immune complexes in freshly drawn sera of patients with various forms of malignancies was detected by the 125I-Clq deviation test of Sobel et al. More than 50% of the 459 cancer sera showed a high inhibition of 125I-Clq uptake by sensitized sheep erythrocytes when compared with sera of 50 healthy laboratory personnel. The levels were compared with levels of total hemolytic complement and immunochemical determinations of Cl1 and C3. A correlation between high levels of circulating immune complexes and low levels of Clq was suggested. These immune complexes were separated by sucrose density gradient ultracentrifugation at low pH and were found to be heavier than 19S. Fluctuation of levels of immune complexes was evident when serial samples from the same patient were tested. Decrease of levels of immune complexes and a concomitant increase of Clq were detected after Calmette-Gueérin bacillus and autologous tumor cell treatment in some melanoma patients.
H Teshima, H Wanebo, C Pinsky, N K Day
Basal and hormone-stimulated prostaglandin biosynthesis was compared in isolated perfused rabbit kidneys with and without ureteral obstruction. At 72 h there was enhanced responsiveness to bradykinin in the ureter-obstructed hydronephrotic kidney. The amount of prostaglandin-like substance released from the perfused kidneys by 25 ng of bradykinin was 533+/-163 ng from the ureter-obstructed, 28+/-4 ng from the contralateral, and 26+/-3 ng from the normal kidney. The enhanced response was also noted with angiotensin II and with norepinephrine. This exaggerated responsiveness by the ureter-obstructed kidney could not be explained by decreased prostaglandin (PG) destruction or by decreased renal peptide inactivation (bradykinin or angiotensin). There was no enhanced PG biosynthesis with exogenous arachidonate, suggesting there was no increase in cyclo-oxygenase activity in the ureter-obstructed kidney. Renal tubular transport of PG from medulla to cortex was apparently not essential for the enhanced PG biosynthesis to hormone stimulation since the same exaggerated responses were noted during perfusion with the ureter ligated. The cyclo-oxygenase inhibitor, indomethacin, increased basal perfusion pressure in the obstructed kidney and enhanced the magnitude and duration of the renal vasoconstriction produced by angiotensin II in the hydronephrotic kidney. These results suggest that the local exaggerated biosynthesis of PG may be occurring in the cortical resistance vessels and may be important to the alteration in blood flow and excretory function that occur in ureteral obstruction.
K Nishikawa, A Morrison, P Needleman
The amino acid gamma-carboxyglutamic acid (Gla) is found in four blood-clotting proteins, in a bone protein, in kidney protein, and in the protein present in various ectopic calcifications. This paper reports the presence of Gla in the EDTA-soluble, nondialyzable proteins of calcium-containing renal calculi including calcium oxalate, hydroxyapatite, and mixed stores of apatite and struvite (MgNH4PO4). Calculi composed of pure struvite and those composed of only uric acid or cystine do not contain Gla. From calcium oxalate and hydroxyapatite stontes, a protein of about 17,000 daltons was obtained which contained about 40 residues of Gla per 1,000 amino acids. The amino acid composition of this protein had no apparent relationship to the Gla-containing bone protein or to the similarly-sized F1 fragment of prothrombin which contains about 64 residues of Gla per 1,000 amino acid residues. The Gla-rich protein in calcium-containing renal stones thus may be a different Gla-containing protein. These data as well as other studies demonstrating the presence of Gla in pathologically calcified tissues not normally containing Gla suggest that the Gla-containing proteins may be of considerable pathophysiological significance.
J B Lian, E L Prien Jr, M J Glimcher, P M Gallop
Intraluminal pressures were measured in the gastric antrum and at different levels of the upper small intestine in 18 normal subjects to investigate whether or not the interdigestive motor complex, identified in several animal species, occurs in man and, if so, to determine its characteristics. In all normal subjects, the activity front of the interdigestive motor complex was readily identified as an uninterrupted burst of rhythmic contraction waves that progressed down the intestine and that was followed by a period of quiescence. Quantitative analysis of various parameters of the complex and simultaneous radiological and manometrical observations revealed that it resembled closely the canine interdigestive motor complex. To test the hypothesis that disorders of this motor complex may lead to bacterial overgrowth in the small intestine, similar studies were performed in 18 patients with a positive 14CO2 bile acid breath test and in an additional control group of 9 patients with a normal 14CO2 breath test. All but five patients had normal interdigestive motor complexes. The five patients in whom the motor complex was absent or greatly disordered had bacterial overgrowth as evidenced by 14CO2 bile acid breath tests before and after antibiotics. These studies establish the presence and define the characteristics of the normal interdigestive motor complex in man. They also suggest that bacterial overgrowth may be due to a specific motility disorder i.e., complete or almost complete absence of the interdigestive motor complex.
G. Vantrappen, J. Janssens, J. Hellemans, Y. Ghoos
The ability of human Hageman factor (coagulation factor XII) to bind to a glass surface and its susceptibility to limited proteolytic cleavage during the contact activation of plasma have been studied using normal human plasma and plasmas genetically deficient in factor XI, prekallikrein, or high molecular weight kininogen (HMWK). When diluted normal plasma containing 125I-Hageman factor was exposed to a glass surface for varying times, the Hageman factor was found to bind to the surface, and within 5 min became maximally cleaved from its native 80,000 mol wt to yield fragments of 52,000 and 28,000 mol wt. Hageman factor in factor XI-deficient plasma behaved similarly. In prekallikrein-deficient plasma, the binding of Hageman factor to the glass surface occurred at the same rate as in normal plasma but the cleavage was significantly slower, and did not reach maximum until 60 min of incubation. Cleavage of Hageman factor in HMWK-deficient plasma occurred at an even slower rate, with greater than 110 min of incubation required for maximal cleavage, although the rate of binding to the glass was again the same as in normal plasma. Normal rates of cleavage of Hageman factor were observed for the deficient plasmas after reconstitution with purified human prekallikrein or HMWK, respectively. These observations suggest that normal contact activation in plasma is associated with proteolytic activation of surfacebound Hageman factor.
Susan D. Revak, Charles G. Cochrane, John H. Griffin
Incubation of peripheral lymphocytes (PBL) from normal donors with pokeweek mitogen (PWM) induced terminal differentiation by B lymphocytes to immunoglobulin (Ig) synthesizing and secreting plasma cells. B cells from hypogammaglobulinemic patients with different primary immunodeficiencies failed to undergo functional differentiation after similar treatment with PWM. Co-cultures of BL from normal donors and hypogammaglobulinemic patients often resulted in deviations, both positive and negative, from expected levels of PWM-stimulated intracellular Ig biosynthesis. Suppression of B-cell differentiation was manifested by PBL from patients with several different primary immunodeficiencies, including infantile sex-linked agammaglobulinemia. Immunoregulatory activities were noted to vary with the normal donor used in co-culture experiments and with time. Cell populations that were active in influencing B-cell differentiation to functional plasma cells did not have an appreciable modulatory effect on T-lymphocyte responses to mitogens. These observations may provide a functional subclassifications for immunoregulatory cells in man.
S A Schwartz, Y S Choi, L Shou, R A Good
Activation of mononuclear cell tissue factor was examined utilizing lipopolysaccharides obtained from wild-type and both Rc and Re mutants of Salmonella typhimurium. Wild-type (smooth) lipopolysaccharide, galactose-deficient (Rc) lipopolysaccharide, heptose-deficient (Re) lipopolysaccharide, and lipid A preparations were all active in their ability to generate tissue factor activity in human mononuclear cells grown in tissue culture. Polymyxin B has been reported to prevent some of the lethal effects of endotoxin in vivo, and the drug reportedly binds to the 2-keto-3-deoxyoctulosonate-lipid A region of the lipopolysaccharide molecule. Polymyxin B was effective in inhibiting the tissue factor generating activity of wild-type lipopolysaccharide, Re lipopolysaccharide, and lipid A in a dose-dependent fashion. Treatment of lipid A preparations with mild alkali abolished the ability of these preparations to activate tissue factor in cells. Analogous to many of the other biologic properties of lipopolysaccharide, tissue factor activation in human mononuclear cells appears to depend upon the integrity of the lipid A portion of the molecule.
F R Rickles, P D Rick
Human aortic smooth muscle cells accumulate only small amounts of cholesteryl esters in tissue culture, even when incubated for prolonged periods with high levels of plasma low density lipoprotein (LDL). This failure to overaccumulate LDL-cholesteryl esters is due to an LDL-mediated feedback suppression of the activity of the cell surface LDL receptor, a regulatory action that limits the rate at which the cells take up LDL. This regulatory system can be bypassed by incubating smooth muscle cells with LDL that has been given a strong positive charge by covalent linkage with N,N-dimethyl-1,3-propanediamine (DMPA-LDL). The unregulated uptake of DMPA-LDL produces a massive deposition of cholesteryl esters in the form of inclusions within the cell. These inclusions take up lipid stains and exhibit positive birefringence with formée crosses that are typical of liquid crystals of cholesteryl esters. By electron microscopy, the cholesteryl ester inclusions appear as homogeneous gray cytoplasmic lipid droplets. The current studies demonstrate that the unregulated uptake of LDL-cholesteryl esters by human aortic smooth muscle cells can reproduce in vitro the major biochemical and morphological alterations that occur within smooth muscle cells in vivo during the process of atherosclerosis.
J L Goldstein, R G Anderson, L M Buja, S K Basu, M S Brown