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PubMed2005

Effect of biogenic substrate concentration on the performance of sequencing batch reactor treating 4-CP and 2,4-DCP mixtures.

Effect of a biogenic substrate (peptone) concentration on the performance of sequencing batch reactor (SBR) treating 220 mg/l 4-chlorophenol (4-CP) and 110 mg/l 2,4-dichlorophenol (2,4-DCP) mixtures was investigated. In this context, peptone concentration was gradually decreased from 300 mg/l to null in which chlorophenols were fed to the reactor as sole carbon and energy sources. By this way, the effect of peptone concentration on observed yield coefficient (Y), biomass concentration, chlorophenols and COD removal performances were investigated. Decreasing peptone concentration accompanied with lower biomass concentration led to increase in peak chlorophenol and COD concentrations within the reactor during each SBR cycle. This, in turn, caused noteworthy declines in the removal rates as chlorophenol degradations followed Haldane substrate inhibition model. Also, increased peak chlorophenol concentrations led to the accumulation of 5-chloro-2-hydroxymuconic semialdehyde (CHMS), which is -meta cleavage product of 4-CP. Despite the decreased removal rates, complete chlorophenols and CHMS degradation, in addition to high COD removal efficiencies (>90%), were observed for all studied conditions, even chlorophenols were added as sole carbon and energy sources. Another significant point is that 2,4-DCP at slightly elevated concentrations (>20 mg/l) within the reactor caused a strong competitive inhibition on 4-CP degradation. In SBR, feeding the influent to the reactor within a certain period (i.e. filling period) provided dilution of coming wastewater, which decreased the chlorophenols concentrations to which microorganisms were exposed. Therefore, use of SBR may help to avoid both self and competitive inhibitions in the treatment of 4-CP and 2,4-DCP mixture especially in the presence high biogenic substrate concentrations. In addition, isolation and identification studies have indicated that Pseudomonas sp. and Pseudomonas stutzeri were dominant species in the acclimated mixed culture.

Biodegradation, Environmental↗
PubMed2002

Optimization of a cultural medium for bacteriocin production by Lactococcus lactis using response surface methodology.

The medium composition for bacteriocin production by Lactococcus lactis ATCC 11454 was optimized using response surface methodology. The selected six factors based on CM medium were sucrose, soybean peptone, yeast extract, KH(2)PO(4), NaCl, and MgSO(4).7H(2)O. Fractional factorial designs (FFD) and the path of steepest ascent were effective in searching for the main factors and approaching the optimum region of the response. By a 2(6-2) FFD, sucrose, soybean peptone, yeast extract, KH(2)PO(4) were found to be significant factors and had positive effects on cell growth, however, only soybean peptone and KH(2)PO(4) were shown to be the two significant factors for bacteriocin production and had negative and positive effects, respectively. The effects of the two main factors on bacteriocin production were further investigated by a central composite design and the optimum composition was found to be 1% sucrose, 0.45% soybean peptone, 1% yeast extract, 2.84% KH(2)PO(4), 0.2% NaCl, and 0.02% MgSO(4) x 7H(2)O. The optimal medium allowed bacteriocin yield to be doubled compared to CM medium.

Bacteriocins↗
PubMed1967

Studies on the endogenous metabolism and senescence of starved Sarcina lutea.

1. When washed suspensions of Sarcina lutea are starved aerobically in phosphate buffer at the growth temperature of 37 degrees , the rate of endogenous oxygen consumption decreases to very low values after 10hr., although many of the cells survive for 40hr. If starvation is prolonged further, the bacteria die at a rate of approximately 1.5% of the initial viable population per hour. 2. Oxidation of intracellular free amino acids accounts for most of the observed endogenous oxygen uptake but RNA is also utilized and a portion of the component bases and pentose is degraded and presumably oxidized. Ammonia appears in the supernatant and some pentose and ultraviolet-absorbing nucleotide are released from the cells. DNA, protein and polysaccharide are not measurably degraded. 3. Survival can be correlated with the ability of aerobically starved bacteria to oxidize exogenous l-glutamate and glucose. When starved under nitrogen for 40hr. cells continue to oxidize their endogenous reserves at undiminished rates when transferred to aerobic conditions; on prolonging anaerobic starvation the rate of oxidation declines during the period of most rapid loss of viability. 4. In the presence of Mg(2+), RNA degradation during aerobic starvation is almost completely suppressed without affecting the period for which the bacteria survive. 5. Cells grown in peptone supplemented with glucose accumulate reserves of polysaccharide which are metabolized in aerobic starvation, together with free amino acids. Ammonia is evolved and RNA is degraded to a greater extent than in peptone-grown suspensions. Bacteria rich in polysaccharide survive less well than those which are deficient in the polymer; the reason for this phenomenon has yet to be established. 6. In peptone medium, endogenous oxygen uptake and the concentration of intracellular free amino acids decline as growth progresses and they continue to decrease when the organism is held in stationary phase. Under the conditions used, the endogenous Q(o2) and free amino acid pool of cells grown in peptone with 2% (w/v) glucose did not decline so markedly and the bacteria contained large amounts of polysaccharide at all stages of growth.

Aging↗
PubMed1997

Fucoidan inhibits leukocyte recruitment in a model peritoneal inflammation in rat and blocks interaction of P-selectin with its carbohydrate ligand.

Neutrophil recruitment into systemic inflammatory sites in vivo is thought to be initiated by selectin-mediated endothelial adherence. The effect of fucoidan (natural sulfated polymer of L-fucose) on the selectin dependent PMN migration into rat peritoneum following the induction of inflammation by peptone injection was studied. Peritonitis was characterized by an increase in the total cell number (from 45.3 x 10(6) to 91.6 x 10(6)/rat), and by highly elevated PMN content (from 0.2% to 58%) in the rat peritoneal cavity 3 h after peptone injection. Intravenous administration of fucoidan was found to reduce, in a dose-dependent manner, neutrophil migration into peritoneum. Fucoidan in a dose as low as 0.8 mg per rat caused 96.8% reduction of neutrophil extravasation. The inhibitory effect of fucoidan was also dependent on the time intervals between the peptone and fucoidan injections. The maximal inhibitory effect of fucoidan was observed within the first 15 min after the induction of peritonitis and it was maintained at a level of 80% during 1.5 h. Administration of fucoidan 2.5 h after peptone injection had practically no effect on PMN extravasation. Since P-selectin is known to play a key role at the earlier stages of PMN extravasation, it was suggested that the inhibitory effect of fucoidan was mostly due to its interaction with P-selectin. The in vitro experiments demonstrated the high affinity of fucoidan for both isolated P-selectin and P-selectin in plasma membranes of activated platelets.

Animals↗
PubMed2005

Nutritional requirements of mycelial growth of Cordyceps sinensis in submerged culture.

AIMS: The nutritional requirements for mycelial growth of Cordyceps sinensis in semi-synthetic liquid media were investigated. The results provide a basis for further physiological study and industrial fermentation of the fungus. METHODS AND RESULTS: Nutritional requirements, including 17 carbohydrates, 16 nitrogen compounds, nine vitamins, four macro-elements, four trace-elements and eight ratios of carbon to nitrogen, were studied for their effects on the mycelial growth in submerged cultures of C. sinensis by using one-factor-at-a-time and orthogonal matrix methods. Among these variables, sucrose, peptone, folic acid, calcium, zinc and a carbon to nitrogen ratio 12 : 1 were identified as the requirements for the optimum mycelial growth. The concentrations of sucrose, peptone and yeast extract were optimized and the effects of medium composition on mycelial growth were found to be in the order sucrose > yeast extract > peptone. The optimal concentration for mycelial growth was determined as 50 g l(-1) sucrose, 10 g l(-1) peptone and 3 g l(-1) yeast extract. CONCLUSIONS: Under optimal culture conditions, over 22 g l(-1) of mycelial biomass could be obtained after 40 days in submerged cultures. SIGNIFICANCE AND IMPACT OF THE STUDY: Cordyceps sinensis, one of the most valued medicinal fungi, is shown to grow in axenic culture. This is the first report on nutritional requirements and design of a simplified semi-synthetic medium for mycelial growth of this psychrophilic species, which grows slowly below 20 degrees C. The results of this study will facilitate research on mass production of the fungus under defined culture conditions.

Carbohydrates↗
PubMed1983

Modified enrichment broth for isolation of Yersinia enterocolitica from nonfood sources.

Sorbitol-bile salts broth was modified by the addition of 0.5% peptone for the enrichment of Yersinia enterocolitica in nonfood samples. A quantitative comparison was made of the growth of Y. enterocolitica in sorbitol-bile salts broth and peptone-sorbitol-bile salts broth at 22 degrees C. Incubation for 48 h resulted in an average 7.79 log10 increase in a viable cell number for six serotypes with peptone-sorbitol-bile salts broth compared with an average 1.85 log10 increase for sorbitol-bile salts broth. Recovery from seeded seawater showed a greater than 100-fold increase in sensitivity with peptone-sorbitol-bile salts broth enrichment. Isolation of indigenous Y. enterocolitica from fresh and marine waters was also significantly enhanced.

Bile Acids and Salts↗
PubMed1981

Hydrophobic peptide auxotrophy in Salmonella typhimurium.

The growth of a pleiotropic membrane mutant of Salmonella typhimurium with modified lipopolysaccharide composition was found to be strictly dependent on the peptone component of complex media. Nutritional Shiftdown into minimal media allowed growth for three to four generations. Of 20 commercial peptones, only enzymatic digests supported growth to varying degrees. Neither trace cations, amino acids, vitamins, carbohydrates, lipids, glutathione, polyamines, carbodimides, nor synthetic peptides stimulated growth; however, cells still metabolized carbohydrates, and amino acid transport systems were shown to be functional. A tryptic digest of casein was fractionated into four electrophoretically different peptide fractions of 1,000 to 1,200 molecular weight which supported growth to varying degrees. The best of these was further fractionated to two highly hydrophopic peptides. N-terminal modifications eliminated biological activity. Fluorescein-conjugated goat antibody to rabbit immunoglobulin G was used as a probe to detect antipeptide antibody-peptide complexes on membrane preparations. Cells grown on peptone distributed the peptide into both inner and outer membranes. The peptide could be removed with chaotropic agents, and cells had to be pregrown in peptone-containing media to bind the hydrophobic peptide. The gene (hyp) responsible for peptide auxotrophy was mapped at 44 to 45 units by conjugation.

Amino Acids↗
PubMed1962

Polymorphism in a marine bacterium in relation to population growth.

Greenfield, Leonard J. (University of Miami, Miami, Fla.), Janet J. Hines, and Linda L. Boral. Polymorphism in a marine bacterium in relation to population growth. J. Bacteriol. 84:357-363. 1962.-A marine pseudomonad, MB-1, from South Florida waters, exists in three forms: orange (y), lemon-yellow (xy), and white (x), each of which is polymorphic. Replicate growth curves of each form were obtained by culturing at 25 C in 1% peptone-sea water using a controlled inoculum. The controlled inoculum was obtained by growing an isolate on a 1% peptone-sea water agar (1.5%) slant for 24 hr at 25 C, transferring a wire loopful of culture to 50 ml of 1% peptone-sea water in a 125-ml flask, and incubating at 25 C for another 24 hr. The resulting bacterial suspension in 0.5-ml amounts was used to inoculate 50 ml of 1% peptone-sea water broths in which growth was measured. The logarithmic growth phase occurred in x and xy between 12 and 18 hr of incubation; in y, this period was between 18 and 24 hr. The stage of growth could also be characterized by the percentage of cell types present at a given period. In late lag phase, single cells outnumbered binary types by about two to one. During logarithmic growth, the single cells predominated by 2.5 or 2.4 to 1. In the stages following this ratio increased, but all cells showed considerable variation in size. Chains of cells were present in all stages but were reduced in number during the logarithmic phase.

Agar↗
PubMed1975

Growth potential of cottonseed culture media for various clinically significant aerobic bacteria.

Enzymatic hydrolysates of various cottonseed flours were prepared with the proteolytic enzymes bromelain, HT-200, Pronase, and trypsin. The growth of various aerobic bacteria of clinical significance in these hydrolysates was compared to that obtained with a standard casein-soybean peptone culture medium, Trypticase soy. The generation times of the majority of bacteria grown in the bromelain cottonseed flour hydrolysate were shorter than that obtained with the standard control broth. A bromelain cottonseed flour hydrolysate agar preparation supported the growth of the bacteria comparably to that of the casein-soybean agar substrate. All the bacterial colonies were larger on the bromelain cottonseed flour hydrolysate blood agar medium than those grown on the control agar. The peptones derived from the enzymatic hydrolysis of cottonseed flour are sufficient to promote the rapid and luxuriant growth of a wide spectrum of aerobic bacteria without the addition of peptone from other sources. It is suggested that cottonseed flour peptones be utilized as a nutrient source in general-purpose media for the clinical microbiology laboratory.

Aerobiosis↗
PubMed1981

Release of somatostatin from rodent antral mucosae maintained in organ culture.

Somatostatin secretion was investigated from rodent antral mucosal biopsies maintained in organ culture. Under control conditions, the somatostatin secretory output was fairly constant, with each biopsy releasing a mean value of 29.1 +/- 7.5 pg of hormone over a 15-min period. Incubation of the mucosa in medium containing 5% peptone directly induced a 20-fold increase in medium somatostatin levels to 622.5 +/- 15.5 pg/ml. In contrast, a peptone dialysate was a weaker stimulant of hormone release, inducing a three- to fourfold increase in medium somatostatin concentration. Additionally, it was determined that a peptic hydrolysate of bovine serum albumin was a significantly more potent in vitro stimulant of somatostatin secretion than the intact undigested molecule. These results suggest that the amino acid and peptide constituents of these proteinaceous substances are the major stimulants of somatostatin release in vitro. It is presently uncertain whether this direct peptone-induced release of somatostatin from antral mucosal explants can account for the previously reported [Am. J. Physiol. 235 (Endocrinol. Metab. Gastrointest. Physiol. 4): E410-E415, 1978] gastrin secretory "off response" to the same agent, because addition of exogenous somatostatin to the medium failed to block this peptone-induced gastrin secretory response.

Animals↗
PubMed1997

Role of gastrin/CCK-B receptors in meal-stimulated acid secretion in rats.

Gastrin is the principal hormonal mediator of gastric acid secretion. Using an in vivo, intact, anesthetized rat model, we studied the role of gastrin/cholecystokinin (CCK)-B receptors in regulating the release of histamine and somatostatin during intragastric stimulation of acid secretion during a peptone meal. In pylorusligated, adult male rats (each implanted with a gastric cannula and portal venous and splenic artery catheters), after a 30-min basal period, gastric acid secretion was stimulated for 90 min either by an intravenous infusion of gastrin-17 (15 micrograms.kg-1.h-1) or by extragastric titration of 5 ml 8% peptone meal at pH 5.5. Basal and stimulated acid outputs and portal venous plasma gastrin, histamine, and somatostatin concentrations were measured before and after close-arterial injection of a new, relatively selective, gastrin/CCK-B receptor antagonist GR143330X. GR143330X reduced basal acid output by 50% but not basal plasma gastrin, histamine, or somatostatin concentrations. GR143330X reduced gastrin-stimulated acid output by 80%, plasma histamine by 70%, and plasma somatostatin by 34%. During intragastric peptone meal stimulation GR143330X reduced the acid response by 42% during the 30- to 60-min period but not during the 60- to 90-min period. GR143330X reduced the plasma histamine response by 72 and 68%, and the plasma somatostatin response by 32 and 54% during the 30- to 60- and 60- to 90-min periods, respectively. GR143330X did not block the gastrin response to peptone at any time. These results indicate that GR143330X is an effective agent for blocking gastrin-stimulated acid secretion and histamine and somatostatin release in rats. Furthermore, we show for the first time in an intact, in vivo, anesthetized rat model that meal-stimulated activation of gastrin/CCK-B receptors stimulates acid secretion in part by regulating the release of histamine and somatostatin.

Animals↗
PubMedDate not supplied

Does the route of feeding modify gastric emptying in rats?

BACKGROUND: It has been shown that the pattern of previous nutrient intake can influence gastric emptying. However, the effect of the absence of enteral stimulation in the setting of a normal energy supply on gastric emptying has not been examined. The aim of this study was to determine whether the absence of enteral stimulation during total parenteral nutrition (TPN) could modify gastric emptying in rats. METHODS: Two experiments were performed. First, gastric emptying of a peptone meal was compared between rats receiving TPN, oral liquid diet (same solution as TPN), or regular diet (control group) for 10 days. In the second experiment, gastric emptying of two test meals (40% peptone and 25% glucose) was studied before and after rats received TPN or intragastric nutrition (same solution as TPN) for 10 to 12 days. RESULTS: In experiment 1, gastric emptying of 40% peptone in the TPN and liquid diet groups was slower than that in the control group. This difference was significant between the TPN group and the control group (p < .01) but not between the liquid diet and control groups (p = .076). Gastric emptying of this meal in the TPN and liquid diet groups was similar. In experiment 2, no difference in gastric emptying of 40% peptone or 25% glucose was found between rats receiving TPN and those receiving intragastric nutrition for 10 to 12 days. CONCLUSIONS: The composition of diet not the route of feeding is important in the modification of gastric emptying by the pattern of previous nutrient intake.

Animals↗
PubMed2001

Optimization of inulinase production by Kluyveromyces marxianus using factorial design.

Factorial design and response surface techniques were used to optimize the culture medium for the production of inulinase by Kluyveromyces marxianus. Sucrose was used as the carbon source instead of inulin. Initially, a fractional factorial design (2(5-1)) was used in order to determine the most relevant variables for enzyme production. Five parameters were studied (sucrose, peptone, yeast extract, pH, and K2HPO4), and all were shown to be significant. Sucrose concentration and pH had negative effects on inulinase production, whereas peptone, yeast extract, and K2HPO4 had positive ones. The pH was shown to be the most significant variable and should be preferentially maintained at 3.5. According to the results from the first factorial design, sucrose, peptone, and yeast extract concentrations were selected to be utilized in a full factorial design. The optimum conditions for a higher enzymatic activity were then determined: 14 g/L of sucrose, 10 g/L of yeast extract, 20 g/L of peptone, 1 g/L of K2HPO4. The enzymatic activity in the culture conditions was 127 U/mL, about six times higher than before the optimization.

Analysis of Variance↗
PubMed2001

Phosphate buffer increases recovery of Escherichia coli O157:H7 from frozen apple juice.

It is common practice to dilute food products in 0.1% peptone before microbiological analysis. However, this diluent may not be appropriate for detection of injured organisms present in acidic foods. Shelf-stable unclarified apple juice (pH 3.6) was inoculated with approximately 1 x 10(7) CFU/ml of Escherichia coli O157:H7 and held at 23 +/- 2 degrees C (control) or frozen to -20 +/- 2 degrees C for 24 h to induce injury before sampling. Unfrozen or frozen and thawed juice was diluted 1:1 or 1:10 in 0.1% (wt/vol) peptone (pH 6.1) or 0.1 M phosphate buffer (pH 7.2). Juice samples were plated onto tryptic soy agar with 0.1% (wt/vol) sodium pyruvate (TSAP) to measure survival or onto sorbitol MacConkey agar (SMA) to indicate injury. Counts on TSAP or SMA were the same for control samples held in peptone or phosphate buffer for up to 45 min. However, populations of E. coli in frozen and thawed samples declined rapidly upon dilution in 0.1% peptone. Within 20 min, E. coli underwent a >1-log10 CFU/ml reduction in viability as measured on TSAP and a >2-log10 CFU/ml reduction to below the limit of detection (1.6 or 2.3 log10 CFU/ml) on SMA. In contrast, populations of E. coli in frozen and thawed samples diluted in phosphate buffer did not decrease significantly on TSAP and decreased by <0.6 log CFU/ml on SMA during a 45-min holding period. The acidity of apple juice appears to interfere with the recovery of freeze-thaw-injured E. coli O157:H7 during sampling. Using 0.1 M phosphate buffer (pH 7.2) as a diluent results in superior recovery of these organisms on both selective and nonselective plating media.

Beverages↗
PubMed2000

[Effect of nutritional conditions on the fermentative production of pyruvic acid by Torulopsis glabrata].

The effects of some nutritional conditions, such as peptone concentration, feeding glucose as well as oxygen supply manner and ratio of C/N in batch culture, on the fermentative production of pyruvic acid by Torulopsis glabrata WSH-IP12 were investigated. In shaking-flask culture: (1) peptone of more than 20 g/L inhibited the accumulation of pyruvic acid; (2) production of pyruvic acid was increased from 23.5 g/L to 30.2 g/L by simply feeding glucose. In 5 L jar-fermentor batch culture: (1) high level of dissolved oxygen and (2) increasing the concentration of glucose and peptone proportionally with constant C/N ratio(26:1) improved the production of pyruvic acid. It was also found that, glucose consumption and pyruvic acid production almost stopped under the condition of nitrogen difficiency while recovered by adding peptone and (NH4)2SO4. By using ammonia water instead of potassium hydroxide for the control of pH, the cells kept stronger ability for synthesizing pyruvic acid within the whole process, 57.3 g/L pyruvic acid with the yield of 0.498 g/g was achieved at 55 h of fermentation.

Candida↗
PubMedDate not supplied

[Optimization of cultivation medium for the production of Bacillus intermedius 3-19 glutamyl endopeptidase].

The effect of some components of cultivation medium on the growth of the streptomycin-resistant Bacillus intermedius strain 3-19 and on the production of glutamyl endopeptidase was investigated using factorial experimental design, which allowed the concentrations of peptone and inorganic phosphate to be optimized for the maximum production of the enzyme. Experiments with different peptones and casamino acids showed that the enzyme production is maximum with peptone 3 of plant origin. The addition of casamino acids or amino acids to the peptone-containing cultivation medium inhibited the production of glutamyl endopeptidase.

Amino Acids↗
PubMed1983

Effects of antibodies to gastric inhibitory peptide on gastric acid secretion and gastrin release in the dog.

Previous studies have questioned the physiological role of gastric inhibitory peptide in inhibiting gastric acid secretion. The present study was designed to examine and compare peptone meal-stimulated gastric acid secretion in dogs after intravenous infusion of rabbit serum containing antibodies to gastric inhibitory peptide or normal rabbit serum (as control). Five dogs were prepared with gastric fistulas. Basal acid output was collected for 90 min through the gastric fistula. After 30 min of basal acid output collection, either rabbit serum containing antibodies to gastric inhibitory peptide or normal control rabbit serum (0.1 ml/kg) was infused intravenously over 1 min. After the basal acid output collection, a 10% peptone meal was infused into the stomach. Gastric acid output was measured by intragastric titration (pH 5.0) for 60 min. Peripheral venous plasma was collected for measurement of gastrin and gastric inhibitory peptide and for binding of endogenous plasma gastric inhibitory peptide by administered antibodies to gastric inhibitory peptide before and at 2, 5, 10, 15, 30, 60, 90, and 120 min after the meal. After intravenous administration of antibodies to gastric inhibitory peptide, 98% +/- 3% (SEM) of endogenous plasma gastric inhibitory peptide was bound by administered antibodies to gastric inhibitory peptide. No binding of endogenous plasma gastric inhibitory peptide was detected after infusion of normal rabbit serum. In dogs receiving intravenous antibodies to gastric inhibitory peptide, both peptone-stimulated gastric acid output and integrated gastrin release responses were increased when compared with dogs receiving normal rabbit serum. With infusion of antibodies to gastric inhibitory peptide, there was a high degree of correlation between the increase in gastric acid output and the increase in integrated gastrin response (r = 0.900, p less than 0.04) that followed the peptone meal. This study, using antibodies to bind endogenous gastric inhibitory peptide, demonstrates the capacity of circulating gastric inhibitory peptide to inhibit meal-stimulated gastric acid secretion. Furthermore, these results support the conclusion that this enterogastrone effect of gastric inhibitory peptide is due, at least in part, to inhibition of gastrin release.

Animals↗
PubMed1980

The activation state of macrophage subpopulations from a murine fibrosarcoma.

We have separated subpopulations of macrophages from an immunogenic fibrosarcoma by the technique of unit gravity velocity sedimentation. The activation state of these subpopulations was determined by measurement of the Fc receptor avidity of adherent cells, and by their 5' nucleotidase and acid phosphatase activity. The subpopulations were compared to resident peritoneal macrophages and the peritoneal macrophage subpopulations elicited by injection of proteose peptone or C. parvum. The results show that two macrophage subpopulations exist within the tumour. The smaller, peroxidase-positive population, with a sedimentation velocity of 1-5 mm/h, is similar to proteose peptone stimulated macrophages with respect to Fc receptor expression, while the other, rapidly sedimenting population (5-9 mm/h) is partially activated. However, neither population achieved the level of activation demonstrated by rapidly sedimenting, C. parvum-activated macrophages. Analysis of the enzyme activity of rapidly adherent macrophages indicated that tumour, proteose peptone or C. parvum macrophages were all activated when compared to resident peritoneal macrophages. No significant differences were found with respect to the elevated levels of acid phosphatase in the three activated macrophage populations, but the 5' nucleotidase activity of C, parvum-elicited macrophages was significantly lower than either the proteose peptone or tumour macrophages. This again demonstrated that the tumour macrophages were less activated than C. parvum macrophages. These data show that tumour-infiltrating macrophages are a heterogeneous population composed of at least two subpopulations existing in different activation states and that within the tumour microenvironment they are not capable of differentiating to the higher activation state, demonstrated by C. parvum macrophages.

Acid Phosphatase↗