Nonenzyme Components Research Articles

The Effect of p-Coumaric Acid on Browning Inhibition in Potato Polyphenol Oxidase-Catalyzed Reaction Mixtures.

There has been considerable interest in using natural polyphenol oxidase (PPO) inhibitors to control browning in fruit and vegetable products. p-Coumaric acid (pCA), a common secondary metabolite of plants, has been studied as an inhibitor of PPOs/tyrosinases from several foods (e.g., mushroom, apple, and potato). However, studies on the use of pCA for the inhibition of PPO-initiated browning in actual food systems are limited. Therefore, a study was carried out to ascertain the efficacy of using pCA to limit PPO-initiated browning in fresh potato juice. The extent of browning inhibition by pCA was shown to be reaction system-dependent. Browning in potato juice was unexpectedly enhanced by the addition of pCA. This was interpreted as pCA acting as an alternative substrate with significantly higher browning efficiency; extent of browning under this condition was higher than that observed in the native potato juice. The addition of pCA to any of the model reaction mixtures (i.e., those containing semi-purified enzymes and substrates) significantly inhibited browning. The discrepancy in pCA effects on browning inhibition in different reaction systems is postulated to be mainly due to non-enzyme and non-substrate components in potato juice that participate in the post-PPO reaction sequences, which ultimately lead to brown color formation.

Effects of 5-aminolevulinic acid on osmotic adjustment and antioxidant system in mung bean under chilling stress

Effects of 5-aminolevulinic acid on osmotic adjustment and antioxidant system in mung bean under chilling stress

ЗОВНІШНЬОСЕКРЕТОРНА НЕДОСТАТНІСТЬ ПІДШЛУНКОВОЇ ЗАЛОЗИ ТА ДИСБАЛАНС СИСТЕМИ ПРООКСИДАНТИ-АНТИОКСИДАНТИ ПРИ ПЕРВИННОМУ ОСТЕОАРТРОЗІ З КОМОРБІДНИМИ СТАНАМИ

У статті розглянуті сучасні погляди на проблему коморбідності первинного остеоартрозу і захворювань, що супроводжуються порушенням зовнішньосекреторної функції підшлункової залози. Проаналізовано рівень активації оксидативного стресу і ослаблення ферментної і неферментної ланок антиоксидантної системи захисту, а також досліджено дефект трофологічного статусу у вітамінній складовій. Дослідниками було встановлено, що найвищий рівень активації процесів пероксидації спостерігався у пацієнтів з первинним остеоартрозом у поєднанні із захворюваннями, що супроводжуються порушенням зовнішньосекреторної функції підшлункової залози. Рівні ферментних і неферментних антиоксидантів були статистично значимо знижені у всіх групах пацієнтів, порівняно з контролем, проте у пацієнтів з первинним остеоартрозом у поєднанні із захворюваннями, що супроводжуються порушенням зовнішньосекреторної функції підшлункової залози, рівні антиоксидантів були статистично значимо найнижчими, порівняно з іншими групами, що свідчить про поглиблення дефіциту показників антиоксидантної системи захисту при коморбідності. Також виявлено поглиблення дефекту трофологічного статусу у вітамінній складовій (токоферол, ретинол, аскорбінова кислота) при коморбідності первинного остеоартрозу із захворюваннями, що супроводжуються порушенням зовнішньосекреторної функції підшлункової залози.

PARAMETERS OF FREE-RADICAL OXIDATION AND ANTIOXIDANT DEFENCE SYSTEM IN RATS OF BOTH SEXES WITH SODIUM NITRITE INTOXICATION

<p>Long-term influence of sodium nitrite on rats causes an increase in lipid peroxidation products in blood and myocardial tissue in animals of both sexes and is accompanied by a decrease in activity of enzymic and non-enzymic components of antioxidant defence system. Under the conditions of intoxication, the process of LPO is less aggressive in females in the comparison with males.</p>

Effect of Aloe vera gel coating on antioxidant capacity, antioxidant enzyme activities and decay in raspberry fruit

Native populations of raspberry fruits (Rubus spp.) were coated with Aloe vera gel and were then assayed for the antioxidant capacity, total anthocyanin, total phenol, antioxidant enzyme activities and postharvest quality after 8 days storage at 4 °C, relative to a control group. These berries, coated with Aloe vera gel, showed a higher antioxidant capacity, total anthocyanin and total phenol than those of the controls (non-treated) group. The treated fruits exhibited less incidence of decay during storage at 4 °C than the control group. Thus postharvest life (as affected by fungal decay) was longer for berries treated with Aloe vera gel than for the control fruit. However, total soluble solid, titratable acidity and pH were predominantly influenced by storage periods. Aloe vera gel treatments could reduce the natural decay that happens over time. The activities of antioxidant enzymes, including glutathione peroxidase (GSH-POD), glutathione reductase (GR), superoxide dismutase (SOD), ascorbate peroxidase (AsA-POD) and guaiacol peroxidase (G-POD) were enhanced. The nonenzyme components such as reduced glutathione (GSH) and oxidized glutathione (GSSG) were also increased by Aloe vera gel. In conclusion, raspberry fruits treated with Aloe vera gel maintained higher levels of antioxidant capacity, total phenol, total anthocyanin and antioxidant enzymes during storage periods.

Differential responses of the antioxidant defence system and ultrastructure in a salt-adapted potato cell line

Changes in lipid peroxidation and ion content and the possible involvement of the antioxidant system in salt tolerance at the cellular level was studied in a potato (Solanum tuberosum L.) callus line grown on 150 mM NaCl (salt-adapted) and in a non-adapted line exposed to 150 mM NaCl (salt-stressed). Salinity reduced the growth rate and increased lipid peroxidation in salt-stressed line, which remained unaltered in the adapted line. Na⁺ and Cl⁻ content increased due to salinity in both lines, but the adapted line displayed greater K⁺/Na⁺ ratio than the stressed one. Total superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2) activities decreased in both salt-exposed lines; catalase (CAT, EC 1.11.1.6) activity did not change in the adapted line, but decreased in the stressed cell line. Salinity caused the suppression of one GR isoform, while the isozyme patterns of SOD, APX, and CAT were not affected. Ascorbate and reduced glutathione increased in both salt-exposed calli lines. α-Tocopherol increased as a result of salt exposure, with higher levels found in adapted calli. Electron microscopy showed that neither the structural integrity of the cells nor membrane structure were affected by salinity, but plastids from adapted cells had higher starch content. The results suggest that the enzymic and non-enzymic components of the antioxidant system are differentially modulated by salt. Different concentrations of antioxidant metabolites are more relevant to the adaptive response to salinity in potato calli than the differences in activity of the antioxidant enzymes.

Variation in antioxidant enzyme activities and nonenzyme components among cultivars of rabbiteye blueberries ( Vaccinium ashei Reade) and V. ashei derivatives

Fruit from 42 blueberry ( Vaccinium species) cultivars, including 36 rabbiteye cultivars ( Vaccinium ashei Reade), 3 V. ashei hybrid derivatives and 3 northern highbush ( V. corymbosum L.) standards, were evaluated for antioxidant activities (AA), levels of antioxidant enzymes [catalase (CAT), ascorbate peroxidase (AsA-POD), glutathione reductase (GR), glutathione peroxidase (GSH-POD), superoxide dismutase (SOD), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR) and guaiacol peroxidase (G-POD)], and antioxidant nonenzyme components [ascorbic acid (ASA) and glutathione (GSH)]. The results of this study showed that cultivars had varying levels of AA, a wide range of antioxidant enzyme activities and various amounts of nonenzyme components. The correlations between AA and all of the enzyme activities or nonenzyme components were positive and high in the 42 cultivars tested in this study. The correlation ( R 2) values between AA and CAT, SOD, DHAR, MDAR, GSH-POD, GR, G-POD and AsA-POD were 0.91, 0.91, 0.91, 0.91, 0.90, 0.90, 0.90, and 0.90, respectively. The correlations between AA and ASA and GSH were 0.94 and 0.92, respectively. Among all 42 cultivars, ‘Early May’ had the highest activities of the AA, AsA-POD, G-POD, DHAR and MDAR and the highest amounts of ASA and GSH, whereas ‘Elliott’ had the highest levels of GR, GSH and SOD.

Effect of allyl isothiocyanate on antioxidant enzyme activities, flavonoids and post-harvest fruit quality of blueberries ( Vaccinium corymbosum L., cv. Duke)

The effect of allyl isothiocyanate (AITC) on antioxidant enzyme activities, flavonoid content, and fruit quality of blueberries var. Duke ( Vaccinium corymbosum L.) was evaluated. Results from this study showed that AITC was effective in maintaining higher amounts of sugars and lower organic acids compared to untreated fruit during storage at 10 °C. However, AITC reduced antioxidant enzyme activities [superoxide dismutase (SOD), guaiacol peroxidase (G-POD), glutathione-peroxidase (GSH-POD), ascorbate peroxidase (AsA-POD), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR) and glutathione reductase (GR)] and non-enzyme components, ascorbate (AsA) and glutathione (GSH). AITC treatments also reduced the amount of phenolic acids (chlorogenic acid, myricetin 3-arabinoside, quercetin 3-galactoside, quercetin 3-arabinoside, and kaempferol 3-glucoside) and anthocyanins (delphinidin 3-galactoside, delphinidon 3-glucoside, delphinidin 3-arabinoside, petunidin 3-galactoside, petunidin 3-glucoside, petunidin 3-arabinoside, malvidin 3-galactoside, and malvidin 3-arabinoside) during storage at 10 °C. The results from this study indicate that AITC does not promote antioxidant property or scavenge constitutive reactive oxygen species (ROS), but maintain blueberry fruit quality through other mechanisms.

Effect of UV treatment on antioxidant capacity, antioxidant enzyme activity and decay in strawberry fruit

The changes in antioxidant capacity, enzyme activity and decay development in strawberry fruit ( Fragaria x ananassa Duch.) illuminated with different UV-C dosages were investigated. Three UV-C illumination durations and dosages, 1, 5 and 10 min, (0.43, 2.15 and 4.30 kJ m −2) tested promoted the antioxidant capacity and enzyme activities and significantly reduced the severity of decay during storage at 10 °C compared to the control. UV-C illumination for 5 and 10 min showed the best results for enhancing antioxidant capacity expressed as oxygen radical absorbance capacity (ORAC) values after storage for 15 days among all the treatments. These treatments also enhanced the activities of antioxidant enzymes including glutathione peroxidase (GSH-POD), glutathione reductase (GR), superoxide dismutase (SOD), ascorbate peroxidase (AsA-POD), guaiacol peroxidase (G-POD), monodehydroascorbate reductase (MDAR), and dehydroascorbate reductase (DHAR). The nonenzyme components such as reduced glutathione (GSH) and oxidized glutathione (GSSG) also were increased by UV-C exposure. All UV-C dosages increased the phenolic content of strawberry fruits as well. Total anthocyanin content increased during storage in all treatments. However, UV-C illumination showed little effect on the anthocyanin accumulation. All UV-C dosages retarded the development of decay comparing to control treatment, but 5 and 10 min UV-C illumination gave the best decay inhibition.

Effect of salicylic acid on the antioxidant system in the pulp of ‘Cara cara’ navel orange ( Citrus sinensis L. Osbeck) at different storage temperatures

Effects of salicylic acid (SA) on active oxygen metabolism and the antioxidant system in the pulp of ‘Cara cara’ navel orange ( C. sinensis L. Osbeck) fruit stored at 6 °C and 20 °C were investigated through analysis of the contents of malondialdehyde and hydrogen peroxide, the activities of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), glutathione reductase (GR, EC 1.6.4.2), dehydroascorbate reductase (DHAR, EC 1.8.5.1) and ascorbate peroxidase (AsA-POD, EC 1.11.1.11), and non-enzyme components such as ascorbate (AsA), dehydroascorbate (DHAsA), glutathione (GSH) and oxidized glutathione (GSSG) in the AsA-GSH cycle. The results showed that the control fruit (dipped in water) had lower contents of malondialdehyde and activities of antioxidant enzymes at 6 °C, and lower contents of ascorbate and glutathione at 20 °C. During storage, the contents of hydrogen peroxide and malondialdehyde together with activities of SOD and CAT gradually increased at both storage temperatures. SA-pretreatment accelerated hydrogen peroxide accumulation and the increase in SOD, but it significantly slowed down malondialdehyde and CAT rate of increase during storage compared to controls under these two temperatures. At the end of storage, malondialdehyde contents in SA-pretreated fruit were 12.6 and 27.6% lower than those in control fruit. The activities of GR and DHAR and the contents of AsA and GSH during fruit storage declined but the SA-pretreatment reduced the rate of this decline. The SA-pretreated fruit had higher values of AsA/DHAsA than those in control fruit at the same temperature, and these ratios were highest at 6 °C. These results indicate that low storage temperature and exogenous SA can reduce lipid peroxidation by regulating the antioxidant system, and suggest that pretreatment with SA combined with lower storage temperature might provide a useful means of maintaining beneficial antioxidant activity during storage of navel orange.

Antioxidant Activities and Anticancer Cell Proliferation Properties of Wild Strawberries

Fruit extracts from 17 to 18 representatives of three strawberry species [Fragaria virginiana Mill., F. chiloensis (L.) Mill., and F. ×ananassa Duchesne ex Rozier] were tested for the ability to inhibit proliferation of A549 human lung epithelial cancer cells. The fruit extracts also were tested for activities against free radicals, (peroxyl radicals, hydroxyl radicals, singlet oxygen, and superoxide radicals), the activities of antioxidant enzymes [glutathione peroxidase (EC 1.11.1.9), superoxide dismutase (EC 1.15.1.1), guaiacol peroxidase (EC 1.11.1.7), ascorbate peroxidase (EC 1.11.1.11), monodehydroascorbate reductase (EC 1.6.5.4), dehydroascorbate reductase (EC 1.8.5.1), and glutathione reductase (EC 1.6.4.2)], and the activities of nonenzyme antioxidant components, ascorbic acid and glutathione. Correlations between the proliferation of cancer cells and these antioxidant activities were calculated. At the species level, F. virginiana fruit extract inhibited the proliferation of A549 human lung epithelial cancer cells to a significantly greater extent (34% inhibition) than the extracts from fruit of either F. chiloensis (26%) or F. ×ananassa (25%) (P < 0.0001). Extracts from fruit of F. virginiana also had significantly greater antioxidant activities and higher activities of antioxidant enzymes and nonenzyme components than did extracts from the other two species. Among individual genotypes, there was a high positive correlation between antiproliferation of A549 cancer cells, antioxidant activities against free radicals, activities of antioxidant enzymes, and activities of nonenzyme components. Although all fruit extracts from all the strawberry genotypes inhibited proliferation of A594 cancer cells, fruit extracts from seven F. virginiana genotypes showed significantly greater antiproliferative effects than any of the F. ×ananassa or F. chiloensis genotypes. These genotypes, CFRA 0982, JP 95-1-1, NC 95-19–1, RH 30, NC 96-48-1, JP 95-9-6, and LH 50-4, may be especially useful in developing cultivars with greater anticancer potential.

(33) Effect of Natural Products on Decay and Antioxidant Activities of Fresh-cut Papayas

The effect of naturally occurring volatile compounds on decay and antioxidant activities in fresh-cut papayas (Carica papaya L.) was studied. Exposure to methyl jasmonate (MJ), methyl salicylate (MS) or allyl isothiocyanate (AITC) substantially delayed the onset and reduced the severity of decay during and after storage at 5 °C. Treatment with tea tree oil (TTO) or ethanol (ETOH) was also effective in retarding decay, but to a lesser extent. No beneficial effect was obtained with the use of vinegar vapor. MJ and MS increased oxygen radical absorbance capacity and elevated the activities of several antioxidant enzymes, including glutathione reductase, glutathione peroxidase, guaiacol peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and superoxide dismutase. The nonenzyme components in the ascorbate-glutathione cycle were also increased by MJ and MS treatments, including ascorbate and glutathione. It is possible that MJ and MS treatments enhanced the antioxidant system and increased the resistance of tissue to decay. However, while AITC also suppressed the development of decay in papaya slices, it had little effect on antioxidant levels and antioxidant enzyme activities. Apparently, AITC exerted its effect through different mechanisms. Studies are in progress to determine if AITC inhibits decay directly via its antimicrobial properties.

UV-B Radiation Suppresses the Growth and Antioxidant Systems of Two Marine Microalgae,Platymonas subcordiformis(Wille) Hazen andNitzschia closterium(Ehrenb.) W. Sm

Abstract: This study investigated whether increased solar UV-B radiation (280–315 nm) could suppress the growth of marine microalgae through effects on their antioxidant systems. Two marine microalgae species, Platymonas subcordiformis (Wille) Hazen and Nitzschia closterium(Ehrenb.) W. Sm, were exposed to a range of UV-B radiation and both showed reductions in their growth rates, and the chlorophyll a (Chl a) and carotenoid (Car) contents when UV-B radiation dose increased. Superoxide anion radical (O2-.) production and the concentration of hydrogen peroxide (H2O2) and malodiadehyde (MDA) also increased with the increasing of UV-B radiation. Antioxidant systems, non-enzymic components (Car and glutathione content) and enzymic components (superoxide dismutase (SOD) and catalase (CAT) activity), decreased as a result of enhanced UV-B radiation. When the exogenous glutathione (GSH) was added, the effects of UV-B radiation on the growth of the two species were alleviated. These results suggest that enhanced UV-B radiation suppressed the antioxidant systems and caused some active oxygen species to accumulate, which in turns retarded the development of the marine microalgae. (Managing editor: Ya-Qin HAN)

Metabolites released by Cryptococcus neoformans var. neoformans and var. gattii differentially affect human neutrophil function

Differences in the ability of Cryptococcus neoformans var. neoformans (CNVN) and var. gattii (CNVG) to establish localized lesions in the lungs of healthy humans remain unexplained. In this study, CNVG infection in a rat model was characterized by early neutrophil invasion into lung tissue, but phagocytosis of cryptococci was not observed. The chemical composition of non-enzymic components secreted by one strain of each variety (heat-inactivated supernatants from CNVN and CNVG, termed vns and vgs, respectively) were compared, using magnetic resonance spectroscopy. Effects on human neutrophil viability and functions at both pH 5.5 and 7.0 were investigated, as the pH of cryptococcomas was found to be 5.4–5.6 in vivo. The supernatants were similar in composition, although metabolites in vns were generally present in higher concentrations. In addition, vgs contained two novel metabolites—acetoin and dihydroxyacetone. Polyphosphate was observed in cells from both varieties and may be a source of extracellular inorganic phosphate. Superoxide production in the presence of phorbol ester was enhanced by treatment with vns and decreased by vgs. At pH 5.5, vns caused high levels of necrosis in neutrophils, as well as increased adhesion/migration through A549 lung epithelial cell monolayers. Individual supernatant components such as polyols, acetoin, dihydroxyacetone, and γ-aminobutyric acid exhibited both pro- and anti-inflammatory properties. Overall, we found that vgs was potentially less pro-inflammatory than vns. Inhibition of neutrophil function by products of CNVG may promote survival of extracellular organisms, and local multiplication to form cryptococcomas.

Correlation of antioxidant capacities to oxygen radical scavenging enzyme activities in blackberry.

The activities of the oxygen radical scavenging enzymes [glutathione-peroxidase (GSH-POD), superoxide dismutase (SOD), and guaiacol peroxidase (G-POD)], hydrogen peroxide scavenging enzymes in the ascorbate-glutathione cycle [ascorbate peroxidase (AsA-POD), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR)], the nonenzyme components [ascorbate (AsA), dehydroascorbate (DHAsA), glutathione (GSH), and oxidized glutathione (GSSG)], and their antioxidant capacity [oxygen radical absorbance capacity (ORAC)] were measured in the juice of six different thornless blackberry (Rubus sp.) cultivars. The 'Hull Thornless' cultivar contained the highest levels, whereas 'Black Satin' consistently had the lowest activities for all the enzymes tested in this study. ORAC values were also the highest in 'Hull Thornless' and lowest in 'Black Satin'. The highest levels of AsA and DHAsA were in the juice of 'Hull Thornless' blackberries with 1. 09 and 0.15 micromol/g fresh wt, respectively. 'Hull Thornless' also had the highest ratio of AsA/DHAsA among the six blackberry cultivars studied. The 'Smoothstem' cultivar contained the lowest amounts of AsA and DHAsA. 'Hull Thornless' had the highest GSH content with 78.7 nmol/g fresh wt, while 'Chester Thornless' contained the largest amount of GSSG. The highest GSH/GSSG ratio was 4.90 which was seen in the 'Hull Thornless' cultivar. The correlation coefficient between ORAC values and AsA/DHAsA ratios was as high as 0.972. A correlation (r = 0.901) was also detected between ORAC values and GSH content. The antioxidant activity in blackberry juice was positively correlated to the activities of most antioxidant enzymes (r = 0.902 with SOD; r = 0.858 with GSH-POD; r = 0.896 with ASA-POD; and r = 0.862 with GR).

Isolation and partial characterization of a novel thermostable carboxylesterase from a thermophilic Bacillus

High levels of esterase activity were detected in cell extracts from a thermophilic Bacillus. A single esterase, with an apparent molecular weight of 38,000–45,000, was purified 56-fold with 48% recovery. The partially purified esterase was fully active when assayed at 85°C and retained 90% of initial activity after exposure to a temperature of 105°C for 150 min. This enzyme, designated G18A7 esterase, showed a greater thermostability, more alkaline pH optimum (pH 9.5), and lower sensitivity to inhibitors than an esterase from Bacillus stearothermophilus strain NCA 2184, [Matsunaga, A. et al. (1974) Arch. Biochem. Biophys. 160, 504–513]. Nondenaturing polyacrylamide gel electrophoresis of samples from various stages of the purification sequence indicated that the enzyme might be present in the cell either as an aggregate of active monomers or associated with nonenzymic components.

Physical properties and non-enzymic components of human ejaculates. Relationship to spontaneous liquefaction.

The relationship between spontaneous liquefaction and the characteristics of ejaculated human semen has been investigated. The liquefaction time of ejaculates was found to be significantly correlated with their extent of coagulation and some non-enzymic components of seminal plasma. Human ejaculates were classified into 3 distinct groups depending on their liquefaction time, and the groups were characterized physico-chemically. The liquefaction time also revealed a low but significant negative correlation with semen volume. It is concluded that an individual's ejaculatory characteristics can be evaluated simply by determining its liquefaction time.

The effect of albumin, ceruloplasmin, and other serum constitutents on Fe(II) oxidation

This study has analyzed the role of several serum constituents, that have been proposed to effect the following reactionin situ: {fx1-1} {fx1-2} These reactions were monitored by measuring the rate of Fe(II) oxidation in the presence of apo-transferrin (reaction A) and Fe(III)-transferrin formation (reaction B) at 465 nm. Reactions A and B were found to be kinetically equivalent. The results show that, singly or in combination, bicarbonate, orthophosphate, citrate, apo-transferrin, and/or albumin have less than one-tenth of the ability to enhance the oxidation of Fe(II) compared to the serum enzyme, ceruloplasmin. It was also found that the rate of Fe(II) oxidation by serum Fe-ligands was influenced by the efficiency of oxygen utilization. Whereas ceruloplasmin produces a 4∶1 ratio of Fe(II) oxidized to oxygen utilized, the non-enzymic components yield a 2∶1 or 3.09∶1 ratio. These data support the role of ceruloplasmin as an antioxidant that prevents the formation of the intermediate active oxygen species O 2 (-) · and H2O 2 (·) through the Fe(II) auto-oxidation reaction.A hitherto unrecognized factor in the control of nonenzymic oxidation of Fe(II) was serum albumin. This protein, at >25 μM, was found to sharply dampen the rate of Fe(II) oxidation in the presence of a physiological concentration of bicarbonate, citrate, and transferrin Albumin did not appear to affect the ceruloplasmin catalyzed oxidation of Fe(II) at pH 7.0. The addition of ceruloplasmin effected up to a 44 × increase in the rate of Fe(II) oxidation and Fe(III)-transferrin formation even in the presence of 0.60 mM albumin.

Incompatibility between Complement Components C3 and C5 of Guinea‐Pig and Man, an Indication of their Interaction in C5 Activation by Classical and Alternative C5 Convertases

The use of heterologous combinations of guinea-pig and human complement components for titration of C5 with convertases of the alternative and classical pathway has been investigated. In addition to the known unfavourable combination of C2hu with C4gp partial incompatibilities were detected between heterologous C3 and C5 as well as between CZhu and C5gp. The incompatibility between heterologous C3 and C5 is of special interest since it indicates an interaction of these two non-enzymic components. Concomitant binding studies have demonstrated that a reduced efficiency of C5 convertases correlates with decreased binding affinity of surface-fixed C3b for C5 when heterologous components are offered. Hence, the present studies give further evidence that surface-bound C3b has the function of a co-factor which binds C5; this interaction is required for C5 activation via the classical as well as the alternative pathway, i.e. by the C3/C5 convertases C42 and C3bB.

The Nonenzymic Histochemistry of Early Oesophagostomiasis and Ostertagiasis in Cattle

Investigations of the histochemistry of calves infected with Oesophagostomum radiatum (Rudolphi) at 8 and 10 days postinoculation and with Ostertagia ostertagi (Stiles) at 8 days postinoculation revealed an increase in the reaction for glycoprotein and a decrease in collagen associated with the lesions produced by the larvae of Oes. radiatum. Such changes in the chemistry of the tissues were not observed in ostertagiasis. In neither infection were alterations in the distribution and abundance of glycogen and acidic mucopolysaccharides detected at this stage. A continuing program of research is being conducted at this laboratory in the histochemistry of the response of the bovine host to infection by the nematodes Oesophagostomum radiatum (Rudolphi, 1803) and Ostertagia ostertagi (Stiles, 1892). This investigation concerns both enzymes and nonenzymic components of the tissue. The present report deals with the nonenzymatic aspects of the histochemistry at a time just prior to the emergence of the first larvae from the tissues in primary