Novel, rapid, low-cost screen-printed (bio)sensors for the direct analysis of boar taint compounds androstenone and skatole in porcine adipose tissue: Comparison with a high-resolution gas chromatographic method.

This is the first report on the fabrication, characterisation and application of an electrochemical (bio)sensor system for the simultaneous measurement of skatole and androstenone. A biosensor for androstenone was fabricated using a Meldola's Blue modified SPCE (MB-SPCE) by depositing NADH and the enzyme 3α-hydroxysteroid dehydrogenase onto the MB-SPCE surface; samples of adipose tissue were analysed using the biosensors in conjunction with chronoamperometry. Cyclic voltammetry was used to investigate the electrochemical behaviour of skatole at a screen-printed carbon electrode (SPCE vs. Ag/AgCl). An oxidation peak was observed around +0.55 V (vs. Ag/AgCl) and differential pulse voltammetry was applied for quantification of skatole in adipose tissue (in-situ). Quantitative analysis was achieved using calibration plots obtained from fortified meat samples. The concentrations obtained by the electrochemical and gas chromatographic (GC) methods demonstrated a good positive correlation. The (bio)sensor system completed both measurements within 60 s, as compared to several hours for GC, and at a considerably reduced cost and complexity. Consequently, the novel (bio)sensor system should have applications for analysis of carcasses on the abattoir processing line.

A novel electroanalytical approach to the measurement of B vitamins in food supplements based on screen-printed carbon sensors.

This paper describes the development of a novel electrochemical assay for the measurement of water-soluble vitamins in food and pharmaceutical products. The optimum conditions for the determination of vitamin B1 (thiamine), B2 (riboflavin) and B6 (pyridoxine) in phosphate buffer were established using cyclic voltammetry in conjunction with screen printed carbon electrodes (SPCEs). The optimum current response for all three vitamins was achieved in 0.1M phosphate buffer pH 11 using an initial potential of -1.0V. Using square wave voltammetry, the linear ranges for thiamine, riboflavin, and pyridoxine were found to be: 15-110µg/ml, 0.1-20µg/ml, and 2-80µg/ml respectively. The application of the method to a commercial food product yielded a recovery of 95.78% for riboflavin, with a coefficient of variation (CV) of 3.38% (n = 5). The method was also applied to a multi-vitamin supplement for the simultaneous determination of thiamine, riboflavin and pyridoxine. In both cases only simple dilution with buffer followed by centrifugation was required prior to analysis. The resulting square wave voltammetric signals were completely resolved with Ep values of -0.7V, +0.2V, and +0.6V respectively. The recoveries determined for the vitamin B complex in a commercial supplement product were found to be 110%, 114%, and 112% respectively (CV = 7.14%, 6.28%. 5.66% respectively, n = 5).

The reduction of starch in finishing diets supplemented with oil does not prevent the accumulation of trans-10 18:1 in lamb meat.

The experiment was conducted to test the hypothesis that the replacement of cereal with low-starch feed ingredients in lambs' finishing diets supplemented with oils could prevent the accumulation of -10-18:1 in meat. Forty lambs were fed 1 of 4 diets supplemented with soybean oil (5.9%) and fish oil (1%) for 6 wk before slaughter. The control (CON) diet contained 43% barley, and in the other diets, barley was completely replaced by dehydrated citrus pulp (DCP), dehydrated sugar beet pulp (DBP), or soybean hulls (SH). Growth performance, feed intake, and carcass and meat quality traits were analyzed. At slaughter, LM samples were collected for gene expression evaluation, and 3 d after slaughter, LM and subcutaneous (s.c.) fat samples were collected for fatty acid analysis. None of the diets affected meat quality, but the DCP diet reduced ADG ( < 0.05) and the DCP and SH diets decreased the feed-to-gain ratio ( < 0.01). The DCP diet increased ( < 0.05) the risk of parakeratosis and the severity of the lesions. Moreover, the DBP treatment led to increased a* (redness) and b* (yellowness) in s.c. fat compared with the CON treatment ( < 0.05). The lipid content of LM did not differ ( > 0.05) with treatment and averaged 34.4 g/kg of meat. Diets had no effect ( > 0.05) on SFA, PUFA, and -MUFA sums and on the -6:-3 ratio in both LM and s.c. fat. A lower expression of fatty acid synthase (FASN) was found with the DCP treatment than with the other treatments ( < 0.001). All treatments showed a high accumulation of -10-18:1, averaging 91 mg/g fatty acid in LM and 147 mg/g fatty acid in s.c. fat. The concentration of -11-18:1 in the tissues was considerably lower than that of -10-18:1, and thus the -10-18:1:-11-18:1 ratio was above 3 with all treatments. Despite this, the SH diet clearly promoted a larger deposition of -11-18:1 and -9,-11-18:2 in tissues compared with the other treatments. () gene expression and SCD activity index in LM were reduced with the SH diet compared with the CON and DCP diets. Overall, these results clearly showed, for the first time, that low-starch/high-NDF diets are not able to prevent the establishment of -10 shifted rumen biohydrogenation pathways, evaluated by the deposition of biohydrogenation intermediates in lamb meat and fat.

Effect of pig breed and dietary protein level on selected fatty acids and stearoyl-coenzyme A desaturase protein expression in longissimus muscle and subcutaneous fat.

The aims of the study were 1) to investigate effects of a low protein diet on fatty acids content and composition of the LM and subcutaneous adipose tissue in 3 genetically diverse breeds, Large White × Landrace, Alentejano, and Bizaro, and 2) to determine whether the effect of the low protein diet of fatty acid composition is associated with dietary modulation of stearoyl-CoA desaturase (SCD) protein expression. The experiments were conducted on 12 Large White × Landrace, 12 Alentejano, and 10 Bízaro female and male pigs. The average animal BW at the beginning of experiments was 40.8, 40.7, and 38.3 kg for Large White × Landrace, Alentejano, and Bízaro, respectively, and the BW of animals at slaughter was 90 kg. The diets contained 202 or 169 g/kg DM of CP (high and low protein diets, respectively) and were balanced in essential AA. The diets were fed until the animals reached 90 kg BW (approximately 73 d). It was established that Large White × Landrace pigs had a less (P = 0.001) total fatty acid content in subcutaneous adipose tissue when compared with Alentejano and Bízaro and less (P < 0.001) intramuscular fat (IMF) content when compared with Alentejano. There was a positive relationship between SCD protein expression in the LM and MUFA content (r = 0.627, P = 0.029) and SCD protein expression and total muscle fatty acids content (r = 0.725, P = 0.008) in Large White × Landrace but not in Alentejano and Bizaro breeds. It has been suggested that SCD protein expression is associated with regulation of fat deposition only in breeds with genetic predisposition to a low IMF content.

Fatty acid composition and lipogenic enzyme protein expression in subcutaneous adipose tissue of male pigs vaccinated against boar taint, barrows, and entire boars.

Objectives of this study were to compare fatty acid composition of subcutaneous adipose tissue of entire boars, barrows, and male pigs vaccinated against boar taint with a vaccine containing a GnRH analogue-protein conjugate (Improvac, Pfizer Animal Health) and to investigate the association between fatty acid composition and protein expression of key lipogenic enzymes in entire boars, barrows, and vaccinated pigs. Differences between groups were observed in the content of total SFA (P≤0.001), MUFA (P=0.035), and n-6 PUFA (P≤0.001) but not n-3 PUFA (P=0.373). Total SFA were greater (P<0.001) in barrows and vaccinated pigs compared with entire animals. This was accompanied by an increase (P<0.05) in the protein expression of the lipogenic enzyme fatty acid synthase in barrows and vaccinated pigs. Total MUFA content was increased (P<0.001) in barrows compared with entire and vaccinated pigs. This was not accompanied (P>0.05) by an increase in expression of stearoyl-CoA desaturase protein, the enzyme catalyzing MUFA biosyntheses. Total n-6 PUFA content did not differ (P<0.001) between entire and vaccinated pigs but was lower in barrows. Expression of Δ6-desaturase protein, one of the key enzymes of PUFA biosynthesis, was greater (P<0.05) in vaccinated pigs than in barrows but did not differ significantly between vaccinated and entire animals. We conclude that fatty acid profile of animals vaccinated against boar taint is similar to that of entire male pigs and that the effect of physical castration and vaccination on fatty acid composition involves changes in lipogenic enzyme protein expression.

Hepatic lipogenic enzyme expression in pigs is affected by selection for decreased backfat thickness at constant intramuscular fat content.

This study investigated (i) whether genetic selection for decreased backfat thickness at constant intramuscular fat (IMF) affects the expression of lipogenic enzymes in pig liver and (ii) whether expression of the hepatic lipogenic enzymes is related to subcutaneous fat and IMF fatty acid composition. The enzymes investigated were fatty acid synthase (FAS), stearoyl-CoA desaturase and Δ6-desaturase (Δ6d). Experiments were conducted on 30 barrows (15 controls and 15 selected). Selected pigs had lower backfat thickness, which was accompanied by a reduced expression of the hepatic FAS and Δ6d when compared to control pigs. There was a trend towards a positive relationship between FAS and Δ6d protein expression and saturated and polyunsaturated fatty acids content respectively, in subcutaneous fat but not in muscle. It was concluded that selection against backfat thickness is associated with changes in expression of the hepatic FAS and Δ6d proteins. The changes in protein expression did not influence significantly the tissue fatty acid composition under these conditions.

Influence of oilseed supplement ranging in n-6/n-3 ratio on fatty acid composition and Δ5-, Δ6-desaturase protein expression in steer muscles.

This study investigated effects of roasted or extruded oilseed supplementation ranging in n-6/n-3 ratios from 0.3 to 5.0 on the fatty acid composition and expression of delta-5 desaturase (Δ5d) and Δ6-desaturase (Δ6d) protein in commercial steer cheek (m. masseter) and diaphragm (pars costalis diaphragmatis) muscles. In general, the n-6/n-3 ratio of the diet had a subsequent effect on the muscle n-6/n-3 ratio (P < 0.05), with muscle 18:2n-6 and 18:3n-3 content relating to proportion of dietary soya bean and linseed (P < 0.01). Compared with canola, pure linseed and soya bean diets reduced 14:1c-9 and 16:1c-9 (P < 0.05) but increased 18:1t-11 and c-9,t-11 conjugated linoleic acid (CLA) content (P < 0.01). Oilseed processing had a minor influence but extruded oilseeds increase 18:1t-11 and c-9,t-11 CLA compared with roasted (P < 0.05). Polar lipid 18:3n-3 and n-3 long-chain polyunsaturated fatty acid (LC, ⩾20 carbons PUFA) derivative content increased in relation to dietary linseed supplementation in the diaphragm (P < 0.01), whereas only 18:3n-3 was increased in the cheek (P < 0.01). Protein expression did not differ between diets; however, in each muscle the Δ5d protein expression had a stronger association with the desaturase products rather than the precursors. The relationship between Δ5d protein expression and the muscle LC n-6/n-3 ratio was negative in both muscles (P < 0.05). The relationship between Δ6d protein expression and the LC n-6/n-3 ratio was positive in the cheek (P < 0.001) and negative in the diaphragm (P < 0.05). In conclusion, diet n-6/n-3 ratio affected muscle 18:2n-6 and 18:3n-3 deposition, whereas the Δ5d and Δ6d protein expression had some influence on the polar lipid LC-PUFA profile. Results reaffirm that processed oilseeds can be used to increase the proportion of fatty acids potentially beneficial for human health, by influencing the formation of LC-PUFA and reducing the n-6/n-3 ratio.

Effect of dietary fatty acids on expression of lipogenic enzymes and fatty acid profile in tissues of bulls.

This study investigated the effects of dietary linolenic acid (C18:3n-3) v. linoleic acid (C18:2n-6) on fatty acid composition and protein expression of key lipogenic enzymes, acetyl-CoA carboxylase (ACC), stearoyl-CoA desaturase (SCD) and delta 6 desaturase (Δ6d) in longissimus muscle and subcutaneous adipose tissue of bulls. Supplementation of the diet with C18:3n-3 was accompanied by an increased level of n-3 fatty acids in muscle which resulted in decrease of n-6/n-3 ratio. The diet enriched with n-3 polyunsaturated fatty acids (PUFAs) significantly inhibited SCD protein expression in muscle and subcutaneous adipose tissue, and reduced the Δ6d expression in muscle. There was no significant effect of the diet on ACC protein expression. Inhibition of the Δ6d expression was associated with a decrease in n-6 PUFA level in muscles, whereas repression of SCD protein was related to a lower oleic acid (C18:1 cis-9) content in the adipose tissue. Expression of ACC, SCD and Δ6d proteins was found to be relatively higher in subcutaneous adipose tissue when compared with longissimus muscle. It is suggested that dietary manipulation of fatty acid composition in ruminants is mediated, at least partially, through the regulation of lipogenic enzymes expression and that regulation of the bovine lipogenic enzymes expression is tissue specific.

Acetyl-CoA carboxylase and stearoyl-CoA desaturase protein expression in subcutaneous adipose tissue is reduced in pigs selected for decreased backfat thickness at constant intramuscular fat content.

The objectives of this study were 1) to determine whether selection toward less subcutaneous fat thickness at constant intramuscular fat content in pigs is related to tissue-specific changes in the expression of lipogenic enzymes acetyl-CoA carboxylase (ACC), stearoyl-CoA desaturase (SCD), and Delta(6)-desaturase (Delta6d); and 2) to investigate tissue specific distribution of the porcine ACC, SCD, and Delta6d. The study was conducted on 20 purebred Duroc barrows. Ten animals were from a group selected for decreased subcutaneous fat thickness at constant intramuscular fat content (experimental group). The other 10 animals were from the unselected (control) group. Distribution of ACC, SCD, and Delta6d was investigated in semimembranosus muscle (SM), subcutaneous adipose tissue (SA), liver (L), kidney (K), heart (H), diaphragm (D), rectus capitis muscle (RCM), and abdominal fat (AF). The enzyme expression was studied in 10 animals in the case of SM and SA and in 4 animals in the case of other tissues. The following expression pattern was established for ACC: SM 0.1) in ACC and SCD protein expression between the control and experimental groups was observed in SM. Expression of Delta6d protein did not differ between the control and experimental groups for SA (P = 0.47) or SM (P = 0.31). There was a positive relationship between muscle SCD protein expression and intramuscular fat content (r = 0.48, P < 0.05). Intramuscular fat content did not correlate with ACC or Delta6d protein expression (P = 0.23 and P = 0.80, respectively). We conclude that SCD might be an effective potential biomarker for intramuscular fat deposition.

Effect of supplementation of the maternal diet with fish oil or linseed oil on fatty-acid composition and expression of Δ5- and Δ6-desaturase in tissues of female piglets.

The present study investigated whether enrichment of the pig maternal diet with n-3 polyunsaturated fatty acids (PUFA) affects the fatty-acid composition of female piglets via enhancing of expression of the lipogenic enzymes Δ5-desaturase (Δ5d) and Δ6-desaturase (Δ6d). The sows (50% Landrace × 50% Large White) were fed a control diet or one of the experimental diets starting at day 45 in gestation. The experimental diets were supplemented either with linseed oil or fish oil, whereas the control diet contained palm oil. Expression of Δ5d and Δ6d, and fatty-acid composition was determined by Western blotting and gas-liquid chromatography, respectively, in muscle, subcutaneous adipose tissue and liver. The highest Δ5d protein expression was observed in the piglets' muscle, followed by subcutaneous adipose tissue, with the lowest level in the liver. Expression of Δ6d in the piglets' tissues followed an opposite pattern, and was highest in the liver, followed by subcutaneous adipose tissue, with the lowest level in muscle. Supplementation of the maternal diet with fish oil or linseed oil increased the level of n-3 PUFA of the piglets in a tissue-specific manner. The response of Δ6d and Δ5d protein expression in female piglets, with average birth weight 2.4 kg, to the dietary manipulation was also tissue-specific. It is suggested that the increase in n-3 PUFA content in the progeny was related, at least partially, to the activation of Δ6d and Δ5d expression.

Expression of 3beta-hydroxysteroid dehydrogenase, cytochrome P450-c17, and sulfotransferase 2B1 proteins in liver and testis of pigs of two breeds: relationship with adipose tissue androstenone concentration.

An excessive accumulation of androstenone in pig adipose tissue is a major contributor to the phenomenon of boar taint. Androstenone deposition is dependent on the rate of androstenone biosynthesis in testis and androstenone degradation in liver. The aim of the current study was to examine the possibility of the existence of breed-specific mechanisms controlling androstenone accumulation in pig adipose tissue. The specific objective was to investigate the expression of some of the key enzymes involved in testicular and hepatic androstenone metabolism in pigs of 2 breeds by using animals with high and low androstenone concentrations within each breed. The study was conducted with Norwegian Landrace (N. Landrace) and Duroc boars. The mean androstenone values for the low- and high-androstenone groups were 0.1 +/- 0.01 microg/g and 7.58 +/- 0.68 microg/g for N. Landrace boars, and 0.22 +/- 0.04 microg/g and 13.55 +/- 1.14 microg/g for Duroc boars. The enzymes investigated were 3beta-hydroxysteroid dehydrogenase (3beta-HSD), cytochrome P450-c17, and sulfotransferase 2B1 (SULT2B1). Expression of cytochrome P450-c17 in liver and testis did not differ between animals with high and low androstenone concentrations in either the N. Landrace or Duroc breed. Expression of hepatic 3beta-HSD, which catalyzes the first stage of androstenone degradation, was decreased in high-androstenone N. Landrace boars (P < 0.01), but not in high-androstenone Duroc boars. In contrast, the expression of hepatic SULT2B1, which catalyzes the second stage of steroid catabolism, was decreased in high-androstenone Duroc animals (P < 0.05), but not in high-androstenone N. Landrace animals. Sulfotransferase 2B1 was also inhibited in testis of high-androstenone pigs of both breeds compared with low-androstenone animals. We report breed differences in expression of the androstenone-metabolizing enzymes 3beta-HSD and SULT2B1 in the liver of high- and low-androstenone pigs. It is suggested that accumulation of androstenone in adipose tissue of N. Landrace boars might be related to a low rate of hepatic androstenone degradation in metabolic stage I, whereas the high androstenone concentration in Duroc boars might be related to a low rate of androstenone metabolism in metabolic stage II.

Relationship between carcass weight, adipose tissue androstenone level and expression of the hepatic 3ß-hydroxysteroid dehydrogenase in entire commercial pigs.

Boar taint is a major meat-quality defect in pigs and is due to excessive accumulation of skatole and androstenone in adipose tissue. The present work investigated the relationship between carcass weight, levels of skatole and androstenone in adipose tissue, and expression of the hepatic androstenone-metabolising enzyme 3ß-hydroxysteroid dehydrogenase (3ß-HSD), in 22 entire male and 22 entire female crossbred pigs (Large White (40%) × Landrace (40%) × Duroc (20%)). Animals of each gender were divided into two subgroups (11 pigs in each subgroup): (i) conventional weight (carcass weight 59 to 77 kg) and (ii) heavy weight (carcass weight 84 to 95 kg). No relationship between carcass weight and adipose tissue skatole level was found for entire male pigs (r2 = 0.013, P > 0.05). There was a significant negative relationship between carcass weight and expression of the hepatic 3ß-HSD protein (r2 = 0.502, P < 0.001) and a significant negative relationship between 3ß-HSD protein expression and androstenone level in adipose tissue (r2 = 0.24, P < 0.05) in entire males. No relationship was found between carcass weight and 3ß-HSD protein expression in female pigs (r2 = 0.001, P > 0.05). 3ß-HSD expression was 59% higher in conventional-weight male pigs when compared with heavy-weight animals (P < 0.05) and 36% higher in heavy-weight females when compared with heavy-weight males (P < 0.05). It is concluded that an increase in slaughter weight of entire commercial crossbred Large White pigs is accompanied by inhibition of expression of the hepatic 3ß-HSD protein, which might result in a reduced rate of hepatic androstenone clearance with its subsequent accumulation in adipose tissue. It is suggested that regulation of pig hepatic 3ß-HSD expression is under the control of sex hormones.

Breed-associated variations in the sequence of the pig 3beta-hydroxysteroid dehydrogenase gene.

The entire sequence of the pig 3beta-hy-droxysteroid dehydrogenase (3beta-HSD) gene has recently become known. This gene is deemed to be important in androstenone metabolism in pig liver, and its defective expression has been shown to be related to androstenone accumulation in adipose tissue and the development of boar taint. The aim of the present work was to do the following: 1) define the structure of the pig 3beta-HSD gene and 2) compare 3beta-HSD DNA sequences from pigs of different breeds, which vary in adipose tissue androstenone levels, with the purpose of identifying a polymorphism that might be responsible for differential 3beta-HSD expression. The 5'flanking and the coding region of 3beta-HSD were cloned and sequenced by conventional techniques. The 3beta-HSD coding regions were identical in pigs of different breeds and in animals with high and low androstenone levels. Significant sequence variations were found in the 5'flanking region of the 3beta-HSD gene, where differences in the number of TTAT repeats and 3 SNP were observed. The SNP were associated with the number of the TTAT repeats. These variations in the DNA sequence of the 3beta-HSD gene were not associated with the androstenone level in s.c. adipose tissue but were breed-dependent. The results of this work might be used for detection of the presence of Meishan genes in Western pig breeds, especially if the phenotype is not clearly established.

Relationship between the expression of hepatic but not testicular 3beta-hydroxysteroid dehydrogenase with androstenone deposition in pig adipose tissue.

This study investigated the relationship between expression of hepatic and testicular 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and accumulation of androstenone in adipose tissue because of its relation to boar taint. The experiments were performed on 13 Large White (50%) x Landrace (50%) and Meishan (25%) x Large White (25%) x Landrace (50%), pigs, which differed in the level of backfat androstenone. Our previous work showed that the major product of the hepatic androstenone metabolism is 3beta-androstenol. In this study, the formation of 3beta-androstenol was inhibited by the specific 3beta-HSD inhibitor trilostane. These results are the first direct confirmation that 3beta-HSD is the enzyme responsible for androstenone metabolism in the pig. The expression of the hepatic but not testicular 3beta-HSD protein showed a negative relationship with the level of backfat androstenone (r2 = 0.64; P < 0.001) and was accompanied by a reduced rate of the hepatic androstenone clearance. Low expression of 3beta-HSD protein in the liver of high androstenone pigs was also accompanied by a reduced level of 3beta-HSD mRNA (P < 0.001), which suggests a defective regulation of the hepatic 3beta-HSD expression at the level of transcription. In contrast, expression of the testicular 3beta-HSD protein did not differ between animals with high and low androstenone levels (P > 0.05) and was lower compared with the hepatic 3beta-HSD expression. Cloning and sequencing of the 3beta-HSD coding regions established that the hepatic and testicular 3beta-HSD cDNA have identical sequences, which were 98% similar to the human 3beta-HSD isoform I. It is suggested that expression of a single 3beta-HSD gene is regulated by different mechanisms in pig liver and testis. The liver-specific regulation of 3beta-HSD expression contributes to the low rate of hepatic androstenone metabolism and therefore can be considered as one of the factors regulating deposition of androstenone in pig adipose tissue and subsequent development of boar taint.

A reduced protein diet induces stearoyl-CoA desaturase protein expression in pig muscle but not in subcutaneous adipose tissue: relationship with intramuscular lipid formation.

A reduced protein diet (RPD) is known to increase the level of intramuscular lipid in pig meat with a smaller effect on the amount of subcutaneous adipose tissue. This might be due to tissue-specific activation of the expression of lipogenic enzymes by the RPD. The present study investigated the effect of a RPD, containing palm kernel oil, soyabean oil or palm oil on the activity and expression of one of the major lipogenic enzymes, stearoyl-CoA desaturase (SCD) and on the level of total lipids and the fatty acid composition of muscle and subcutaneous adipose tissue in pigs. The RPD significantly increased SCD protein expression and activity in muscle but not in subcutaneous adipose tissue. The level of MUFA and total fatty acids in muscle was also elevated when the RPD was fed, with only small changes in subcutaneous adipose tissue. A positive significant correlation between SCD protein expression and total fatty acids in muscle was found. The results suggest that an increase in intramuscular but not subcutaneous adipose tissue fatty acids under the influence of a RPD is related to tissue-specific activation of SCD expression. It is suggested that the SCD isoform spectra in pig subcutaneous adipose tissue and muscle might be different.

Vitamin K administration in neonates: survey of compliance with recommended practices in the Dunedin area.

AIMS: A three dose oral regimen for vitamin K prophylaxis was introduced as an alternative to a single intramuscular injection in August 1992. An assessment of the acceptance of this regimen was needed to determine if the risk of developing haemorrhagic disease of the newborn had altered. METHODS: A survey of compliance with the recommendations was made using a telephone questionnaire to 179 parents. RESULTS: One hundred and fifty three breast fed infants received oral vitamin K. Repeated doses were given to 133 (97%) of 138 breast fed infants at 1 week and 115 (94%) of 122 breast fed infants at 6 weeks. Twenty three of the infants were given the third dose of vitamin K later than recommended. CONCLUSION: Although the majority of infants received all three recommended doses, a quarter of infants given oral prophylaxis are at an increased risk of haemorrhagic disease of the newborn in our sample population.

Peptidoleukotriene (pLT) release from guinea pig lung mast cells.

Guinea pig lung mast cells can be isolated and purified to high purity. This has given us the opportunity to study in greater detail mediator release from these cells. Both immunologic (ovalbumin sensitized) and nonimmunologic (calcium ionophore, CaI) stimuli caused a dose-dependent release of histamine and pLT from monodispersed lung cells and highly purified lung mast cells. Examination of the time release curve for pLT revealed a 5-min lag in the release of this mediator and a peak release at 60 min after challenge with antigen. Verification of pLT release was obtained by use of the 5-lipoxygenase inhibitor A64077 (Zileuton). Pretreatment of lung mast cells with the 5-lipoxygenase inhibitor prevented release of pLT by either antigen or CaI but had no appreciable effect on histamine release (HR). The pulmonary mast cell appears to be an important contributor to pLT release in the guinea pig lung.

Pharmacologic modulation of the influence of the epithelium on immunologic- and nonimmunologic-induced histamine release and contraction in guinea pig superfused tracheal strips.

The influence of the epithelium on contractions and histamine release evoked by ovalbumin and d-tubocurarine has been examined in guinea pig superfused tracheal strips under several experimental conditions. Without drug pretreatment, removal of the epithelium resulted in larger (P < .05) total histamine released by ovalbumin, 10(-4) to 10(-1) mg/ml, and by d-tubocurarine, 3 x 10(-3) M. In the presence of indomethacin, 5 x 10(-6) M, epithelium removal resulted in elevated histamine release only at smaller ovalbumin concentrations, 10(-4) and 10(-3) mg/ml. Indomethacin did not change the influence of the epithelium on histamine release by d-tubocurarine. Indomethacin treatment abolished the influence of the epithelium on ovalbumin-induced tracheal contraction. With indomethacin, larger (P < .05) histamine release was seen with ovalbumin, 10(-1) and 1 mg/ml, when the epithelium was intact. The larger histamine release in response to ovalbumin, 10(-1) mg/ml, in the presence of the epithelium was unaltered by pyrilamine, 10(-6) M, cimetidine, 10(-4) M, and thioperamide, 10(-6) M, to block histamine H1, H2 and H3 receptors, respectively. Therefore, histamine released by ovalbumin does not stimulate histamine release through an action on these receptors when the epithelium is intact. In the presence, but not in the absence, of the epithelium, A64077, 10(-5) M, and ICI198615, 10(-8) and 10(-6) M, inhibitors of 5-lipoxygenase and LTD4/E4 receptors, respectively, inhibited histamine release by ovalbumin, 10(-1) mg/ml. Histamine release by ovalbumin, 10(-4) mg/ml, and d-tubocurarine, 3 x 10(-3) M, studied with or without epithelium was not altered by A64077 or ICI198615.(ABSTRACT TRUNCATED AT 250 WORDS)