Pulmonary aspiration studied by radionuclide milk scanning and barium swallow roentgenography

We have examined the use of radionuclide milk scanning to detect aspiration and have compared the clinical features of patients with demonstrated aspiration with those of patients in whom aspiration was not demonstrated. One hundred twenty children underwent radionuclide milk scanning for three different clinical indications, namely, respiratory tract symptoms (n = 56), gastroesophageal (GO) reflux (n = 20), and near-miss sudden infant death syndrome (SIDS) (n = 44). Ninety-eight (82%) of the 120 patients had a GO reflux demonstrated on the radionuclide milk scan. The incidence of aspiration was high in the respiratory (23%) and near-miss SIDS groups (20%) but low in the GO reflux group (5%). Only four of the 19 patients with an aspiration-positive scan had an aspiration-positive barium swallow film. The clinical symptoms and signs of those patients with aspiration-positive results were not significantly different from those of patients in whom aspiration was not demonstrated. We conclude that radionuclide milk scanning is more sensitive than barium swallow roentgenography in detecting aspiration; however, the clinical significance of such aspiration is undetermined. In view of the high incidence of GO reflux demonstrated in the absence of aspiration by the use of radionuclide milk scanning, the sole finding of GO reflux in a child with respiratory tract symptoms should not be taken as presumptive evidence that aspiration is contributing to those symptoms.

Inhibition of interleukin 1 activity by a factor in submandibular glands of rats

With the sequential use of ammonium sulfate precipitation, gel filtration and chromatofocusing, we have partially purified from extracts of the submandibular glands of rats a factor (referred to as submandibular gland's immunosuppressive factor or SMG-ISF) capable of inhibiting the in vitro proliferation of mitogen- and antigen-stimulated murine lymphocytes. The semi-purified suppressor fractions had an isoelectric point of 4.4 to 4.5 and consisted of at least three molecular species. These active fractions suppressed the mitogenic effects of Concanavalin A phytohemagglutinin, and lipopolysaccharide. In vitro immune reactions such as the mixed lymphocyte culture MLC reaction and the production of cytotoxic T lymphocytes (CTL) across major histocompatibility barriers in mice were also suppressed. These in vitro immunosuppressive effects required the addition of the suppressor fractions early after the initiation of the cultures and were reversed if the factor was removed from the cultures at least 48 to 72 hr before the completion of the assays. The active fractions did not affect the proliferation of CTLL 2 cells induced by interleukin 2 (IL 2), but inhibited the mitogenic and co-stimulatory effects of IL 1 on mouse thymocytes, and in this effect showed a dose-response relation suggestive of a competitive mechanism. These characteristics of SMG-ISF indicate a specific inhibition of the activity of IL 1.

Inhibition of interleukin 1 activity by a factor in submandibular glands of rats

With the sequential use of ammonium sulfate precipitation, gel filtration and chromatofocusing, we have partially purified from extracts of the submandibular glands of rats a factor (referred to as submandibular gland's immunosuppressive factor or SMG-ISF) capable of inhibiting the in vitro proliferation of mitogen- and antigen-stimulated murine lymphocytes. The semi-purified suppressor fractions had an isoelectric point of 4.4 to 4.5 and consisted of at least three molecular species. These active fractions suppressed the mitogenic effects of Concanavalin A phytohemagglutinin, and lipopolysaccharide. In vitro immune reactions such as the mixed lymphocyte culture MLC reaction and the production of cytotoxic T lymphocytes (CTL) across major histocompatibility barriers in mice were also suppressed. These in vitro immunosuppressive effects required the addition of the suppressor fractions early after the initiation of the cultures and were reversed if the factor was removed from the cultures at least 48 to 72 hr before the completion of the assays. The active fractions did not affect the proliferation of CTLL 2 cells induced by interleukin 2 (IL 2), but inhibited the mitogenic and co-stimulatory effects of IL 1 on mouse thymocytes, and in this effect showed a dose-response relation suggestive of a competitive mechanism. These characteristics of SMG-ISF indicate a specific inhibition of the activity of IL 1.

Photoaffinity labeling of peptide binding sites of prolyl 4-hydroxylase with N-(4-azido-2-nitrophenyl)glycyl-(Pro-Pro-Gly)5

The synthesis is described of the photoaffinity label N-(4-azido-2-nitrophenyl)glycyl-(Pro-Pro-Gly)5 for the peptide binding site of prolyl 4-hydroxylase. The photoaffinity label is a good substrate and is capable of light-induced inactivation of prolyl 4-hydroxylase activity. Inactivation depends on the concentration of photoaffinity label and is prevented by competition with excess (Pro-Pro-Gly)5. Two moles of photoaffinity label per mole of enzyme is needed for 100% inactivation of enzymic activity. Oxidative decarboxylation of 2-oxoglutarate measured in the absence of added peptide substrate is not affected by labeling. We conclude that the covalently bound nitreno derivative of N-(4-azido-2-nitrophenyl)glycyl-(Pro-Pro-Gly)5 acts by preventing the binding of peptide substrate to the catalytic site without interfering with the binding of the other substrates and cofactors 2-oxoglutarate, O2, Fe2+, and ascorbate. Labeling is specific for the alpha subunit of the tetrameric alpha 2 beta 2 enzyme. In addition to two catalytic binding sites that are blocked by the photoaffinity label, the enzyme contains binding subsites for peptide substrates, as judged from the capability of photoinactivated enzyme to bind to a poly(L-proline) affinity column. These binding subsites may account for the rapidly increasing affinity for peptide substrates with increasing chain length.

Suppression and enhancement of in vitro lymphocyte reactivity by factors in rat submandibular gland extracts

The addition of crude extracts from rat submandibular (SM) glands to murine spleen and lymph node cell cultures stimulated with concanavalin A (Con A) induced either suppression (at high concentrations) or further stimulation (at lower concentrations) or further stimulation (at lower concentrations) of proliferative activity. Gel filtration of the extracts revealed that suppressive activity was due to factors of molecular weight in the 50,000-96,000 range, while stimulation was due to factors in the 13,000-35,000 molecular weight range. The suppressor activity of the higher molecular weight fractions was not due to a reduction of cell viability or of the uptake of tritiated thymidine. This was demonstrated by the fact that the addition of IL-2 to the cultures completely reversed the suppressive effect. Further fractionation of the suppressive and of the stimulatory gel filtration fractions with the chromatofocusing technique led to the identification of a single fraction with suppressor activity and of multiple discrete fractions with stimulatory activity.

Inhibition of energy-transducing reactions by 8-nitreno-ATP covalently bound to bovine heart submitochondrial particles: direct interaction between ATPase and redox enzymes

The photoaffinity label 8-azido-ATP has been used to study the effect of inhibition of ATP synthase on ATP-driven reverse electron transfer from succinate to NAD+ ('reversal'), succinate- and NADH-driven ATP synthesis and ATP-Pi exchange. In reversal, where ATPase functions as primary proton pump, inactivation by covalently bound nitreno-ATP results in an inhibition that is proportional to the inactivation of ATP hydrolysis, or, consequently, with the concentration of inactivated ATP synthases. Up to 60% inactivation of the reversal rate does not lead to a decrease in delta mu H+. Inhibition of ATP synthase as secondary proton pump results in case of NADH-driven ATP synthesis in a proportional inhibition, but with succinate as substrate ATP synthesis is less than proportionally inhibited, compared with inactivation of ATP hydrolysis. Inhibition of one of the primary pumps of NADH-driven ATP synthesis, the NADH:Q oxidoreductase, with rotenone also resulted in an inhibition of the rate of ATP synthesis proportional to that of the NADH oxidation. ATP-Pi exchange is much more affected than ATP hydrolysis by photoinactivation with 8-azido-ATP. Contrary to reversal and NADH-driven ATP synthesis the rate of ATP-Pi exchange does not depend linearly, but quadratically on the concentration of active ATP synthases. The observed proportional relationships between inhibition of the primary or secondary pump and the inhibition of the overall energy-transfer reactions do not support the existence of a pool intermediate in energy-transduction reactions. However, the results are consistent with a direct transfer of energy from redox enzymes to ATP synthase and vice versa.

The use of 8-azido-ATP and 8-azido-ADP as photoaffinity labels of the ATP synthase in submitochondrial particles: evidence for a mechanism of ATP hydrolysis involving two independent catalytic sites?

8-Azido-ATP is a substrate for the ATP synthase in submitochondrial particles with a Vmax equal to 6% of the Vmax with ATP. The Km values for 8-azido-ATP are similar to those for ATP. ATP synthase in submitochondrial particles can bind maximally 2 mol 8-N-ATP or 8-N-ADP per mole and the inhibition of ATP hydrolysis by covalently bound N-ATP or N-ADP is proportional to the saturation of the enzyme with inhibitor, similar to the results obtained with isolated F1. Both 8-N-ATP and 8-N-ADP are bound mainly to the beta subunits and at all levels of saturation the distribution of the label is 77% to the beta and 23% to the alpha subunits. It is proposed that the binding of 8-azido-AXP itself is mainly to the beta subunit, but that part of the nitreno radicals formed during excitation with light reacts with an amino acid of the alpha subunit, due to the location of the binding site at an interface between a beta and an alpha subunit. Partial saturation with 8-N-ATP, under conditions that the concentration of 8-azido-ATP during the incubation is intermediate between the low and high Km values, does not abolish the apparent negative cooperativity of ATP hydrolysis. It is concluded that this apparent cooperativity is not due to the presence of two different catalytic sites, nor to a cooperativity between the two catalytic sites, but to interaction between the catalytic sites and regulatory sites.

Perennial rhinitis. A common childhood complaint

Symptoms of rhinitis in 595 children who attended an allergy clinic over a four-year period were examined to determine the relative frequencies of perennial rhinitis and seasonal rhinitis (hay fever). Perennial rhinitis was much more common than seasonal rhinitis at all ages, and only 12% of children with rhinitis had symptoms restricted to the grass pollen season. The detection of eosinophils in nasal smears from subjects with rhinitis was uncommon (10% of cases), while mast cells were found in one third of cases. Rhinitis was the most common symptom of atopic disease.

Lymphomatoid papulosis in an 11-month-old infant

Lymphomatoid papulosis was seen in an 11-month-old child. The condition resolved spontaneously after a course of only 8 weeks and the patient has now been disease free for 9 months. Electron microscopy showed infiltrating lymphocytes with cleaved nuclei suggestive of T cells. Monoclonal antibody studies confirmed the T cell nature of the infiltrate. In this case, suppressor (OKT8) T cells were more prominent than helper (OKT4) T cells, in contrast to previous reports.

Stoicheiometry and kinetics of the prolyl 4-hydroxylase partial reaction

In the absence of a peptidylproline substrate, the oxidative decarboxylation of 2-oxoglutarate by prolyl 4-hydroxylase (prolyl-glycyl-peptide,2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2) is stoicheiometrically coupled to the oxidation of ascorbate. The Km and Kd for O2 in this partial reaction are 1.5 mM, this value being one order of magnitude higher than the Km and Kd for O2 in the complete reaction in the presence of (Pro-Pro-Gly)5, indicating that in this case O2 can become enzyme-bound predominantly after the interaction of the peptide substrate with the enzyme. The Km values for 2-oxoglutarate in the partial and the complete reactions are the same. In the absence of both a peptide substrate and ascorbate 2 mol CO2 per mol enzyme are produced in the first 1-1.5 min, during which the enzyme becomes inactivated and, as shown earlier (De Jong , L., Albracht , S.P.J. and Kemp, A. (1982) Biochim. Biophys. Acta 704, 326-332) enzyme-bound Fe2+ becomes oxidized to Fe3+. The results are consistent with a mechanism in which a Fe2+O complex is the O-transferring intermediate involved in peptidylproline hydroxylation.

Two Fe2+ atoms are present in activated prolyl 4-hydroxylase

A linear relationship was found between the activity of prolyl 4-hydroxylase (EC 1.14.11.2) and the amount of Fe2+ bound per mol enzyme. At maximal activity (2.1 mumol X min-1 per mg protein) the enzyme contains 2.1 mol Fe2+ specifically bound per mol enzyme tetramer, indicating two Fe2+-binding sites on prolyl 4-hydroxylase. The half-maximal concentration of added Fe2+ for enzyme activity depends on the nature of sulphydryl compounds present in the reaction medium.

The influence of 2-oxoglutarate on the activity of prolyl 4-hydroxylase

1. Treatment of prolyl 4-hydroxylase (prolyl-glycyl-peptide, 2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2) with 2-oxoglutarate in the absence of added Fe2+ for 10 s causes partial inactivation of the enzyme which is not reversed by subsequent addition of Fe2+. It appears that 2-oxoglutarate prevents loss of enzyme-bound iron and prevents access of added iron to its binding site. 2. For optimal enzyme activity the enzyme should be preincubated for 15 s with Fe2+ (5 microM). 3. Under turnover conditions prolyl 4-hydroxylase does not release iron. 4. The inactivation brought about by pre-incubation with 2-oxoglutarate and O2 in the absence of ascorbate is partly reversed by removal of 2-oxoglutarate. 5. It is proposed that dead-end complex formation with 2-oxoglutarate is responsible for the inactivation of the enzyme by 2-oxoglutarate in the absence of either ascorbate or Fe2+. 6. Optimal enzyme activity is obtained if the reactants are added to the reaction medium in the following order: enzyme, iron and ascorbate in any order, then after at least 15 s 2-oxoglutarate and finally (Pro-Pro-Gly)5 to start the reaction.

Prolyl 4-hydroxylase activity in relation to the oxidation state of enzyme-bound iron. The role of ascorbate in peptidyl proline hydroxylation

In agreement with others (Myllylä, R., Kuutti-Savolainen, E.-R. and Kivirikko, K.I. (1978) Biochem. Biophys. Res. Commun. 83, 441-448), it was found that, in the absence of ascorbate, prolyl 4-hydroxylase (prolyl-glycyl-peptide, 2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2) catalyses the hydroxylation of peptidyl proline, stoicheiometrically coupled to the oxidative decarboxylation of 2-oxoglutarate, at a high initial rate. Under these conditions the enzyme becomes inactivated by at least 90% within 1 min in the presence of 400 microM 2-oxoglutarate, in the presence or absence of the peptide substrate (Pro-Pro-Gly)10. The enzyme can be partly reactivated by ascorbate, but not by Fe2+. Addition of a stoicheiometric amount of iron to the enzyme gives rise to a small EPR signal at g = 4.3, which is typical of a high-spin d 5 ion in a rhombic environment. After subsequent incubation for 30 s at 37 degrees C in the presence of 2-oxoglutarate, the amplitude of the EPR signal at g = 4.3 increases 3-4-fold and corresponds to virtually all of the iron added. In addition, an EPR signal at g = 2.0 is formed under these conditions. The signal at g = 4.3 decreases after subsequent addition of ascorbate. It is concluded that in the presence of 2-oxoglutarate enzyme-bound Fe2+ is rapidly converted to Fe3+, leading to inactivation of the enzyme. Enzyme-bound Fe3+ can be reduced again by ascorbate, thus reactivating the enzyme, or, in the absence of 2-oxoglutarate, by Fe2+.

Nitrate poisoning in cattle. 7. Prevention

Results are summarized from 44 feeding trials with dry or lactating cows fed hay, pre-wilted grass silage or freshly mown grass with or without concentrates. As nitrate content of the forage increased, the moment at which the highest methaemoglobin (MHb) concentration occurred was delayed. As the MHb peak increased, more time was required to reduce MHb to normal values of 2-3%. Dry matter (DM) intake varied with type of forage. Consumption of 1.1 kg DM/100 kg bodyweight required 2 hours with hay or silage and 3.5 h with fresh grass. The relationship between nitrate intake and the formation of MHb in the blood was used to calculate the amount of forage that may be consumed per meal without causing symptoms of nitrate poisoning. Hay and pre-wilted silage with a nitrate content of up to 0.75% in the DM may be given ad lib. Indoor feeding of freshly mown grass with a nitrate content of up to 1.5% may also be given with restriction. Under grazing conditions, grass with a nitrate content of 2% in DM was safe without restriction. Nitrate poisoning may also be prevented by inhibiting nitrate reduction in the rumen by a daily dose of tungsten (wolfram). However, all potential hazards of this prophylactic treatment need to be examined before its use under practical conditions can be recommended. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Deficient natural killer cell activity in a patient with Fanconi's anaemia and squamous cell carcinoma. Association with defect in interferon release

A child with Fanconi's anaemia diagnosed at 7 years of age presented in adult life with lymphopenia, recurrent warts and Bowen's disease. The latter resulted in the development of multiple cutaneous squamous cell carcinomas which metastasized to the skeleton. Investigation of her immune function revealed selective defects in natural killer (NK) cell activity. Humoral immunity and several tests of cell-mediated responses were within normal or became normal after treatment with levamisole or transfer factor. Analysis of the defect in NK activity revealed that low levels could be induced in vitro by fibroblast interferon. Stimulation of blood lymphocytes from the patient with the interferon inducer poly (I)-poly (C) resulted in an increase in NK activity but incubation of her lymphocytes on tumour cells did not result in an increase in NK activity or the release of interferon. This contrasted with the marked increase in NK activity and interferon release observed when lymphocytes from normal controls were incubated on tumor cells. These findings suggested the absence of NK activity in this patient was secondary to a defect in interferon release from lymphocytes on exposure to tumour antigens. It is considered that these defects may have been an important predisposing factor in the development of malignancy in this patient and possibly other patients with Fanconi's anaemia.

Dissociation and reassociation of prolyl 4-hydroxylase subunits after cross-linking of monomers

1. Incubation of prolyl 4-hydroxylase (prolyl-glycyl-peptide, 2-oxoglutarate : oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2) with H2O2 leads to a decrease of 50% in the specific activity of enzyme tetramers, followed by dissociation into inactive dimers in which the monomers are covalently cross-linked by S-S bridge formation. 2. Incubation of the enzyme with K3Fe(CN)6 leads to a comparable decrease in activity of enzyme tetramers. Addition of urea leads to dissociation into inactive dimers with similarly cross-linked monomers. 3. Removal of the dissociating agent leads to reassociation of cross-linked dimers to tetramers and to about 50% reactivation. The enzyme is further reactivated by preincubation with dithiothreitol. 4. Dissociation of the enzyme with dithiothreitol, urea or LiCl, or at low pH (4.15) produces inactive monomers, which could not be reassociated.

Cross-reactivity of anti-acetylcholine receptor autoantibodies

The heterogeneity of the specificities of anti-acetylcholine receptor (anti-AChR) antibodies of myasthenia gravis (MG) patients has been demonstrated by comparing reactions against a panel of xenogeneic AChR. For each patient there was a more or less unique cross-reactivity profile. Such heterogeneity emphasizes the need to use human AChR for the routine detection of anti-AChR. In vitro cross-reactivity was important in predicting the effect of anti-AChR after passive transfer to rats. Specificity may influence the outcome in human neonates receiving maternal anti-AChR via the placenta. In contrast to the extreme heterogeneity seen in spontaneous MG, the antibodies associated with D-penicillamine-induced MG were more homogeneous.

Photolabelling with 8-azido-adenine nucleotides of adenine nucleotide-binding sites in isolated spinach chloroplast ATPase (CF1)

1. Photolabelling of chloroplast ATPase (CF1) with either 8-azido-ATP or 8-azido-ADP leads to inactivation of the ATPase activity. ATP and ADP protect against the inactivation, whereas AMP dose not. 2. Ca2+ has little if any effect on the degree of inactivation by photolabelling with 8-azido-ADP, but, at the same degree of inactivation, twice as much label is bound in the presence of Ca2+ as in its absence. 3. The degree of inactivation of ATPase and the amount of bound photolabel are independent of the extent of pre-activation of the CF1. 4. Upon extrapolation to complete inactivation, 2 mol label, either 8-azido-ATP or 8-azido-ADP can be bound. 5. In all cases the label is bound specifically to the alpha and beta subunits in almost equal amounts. The location of the bound label is not affected by addition of Ca2+, ATP or ADP.

Serum thyroglobulin, its autoantibody and thyroid stimulating antibodies in the endocrine exophthalmos

Serum concentrations of thyroglobulin, its antibody, and thyroid stimulating antibodies were studied in 32 patients referred to a department of eye-diseases for exophthalmos. Twenty-three of the patients were or had been medically treated for Graves' disease, one had toxic nodular goitre, one subclinical myxoedema, three euthyroid exophthalmos and four were shown to have non-endocrine eye-disease.

In patients with medically treated Graves' disease serum thyroglobulin was significantly elevated (P < 0.02), the still toxic patients accounting for the highest values. Both thyroid stimulating and thyroglobulin antibodies were detectable in 4 of 18 patients. The rest of the patients had normal concentrations of thyroglobulin and undetectable thyroid stimulating antibodies, but 3 patients had measurable thyroglobulin antibodies. In Graves' patients there was no correlation between serum concentrations of thyroid stimulating antibodies and thyroglobulin, and no clear difference between the frequency of thyroid stimulating or thyroglobulin antibodies in the patients with persistent elevation of circulating thyroid hormones and those remaining euthyroid.

A relation between the thyroid autoantibodies, thyroglobulin and the thyroid hormonal level or severity of the exophthalmic state could not be demonstrated.

It is suggested that hyperthyroidism and exophthalmos are separate disorders, and immunological phenomena probably involved in the pathogenesis of exophthalmos associated with Graves' disease appear to be reflected only locally.

Nitrate poisoning in cattle. 6. Tungsten (wolfram) as a prophylactic against nitrate-nitrite intoxication in ruminants

The amount of nitrite formed in the rumen after supply of potassium nitrate was decreased considerably by tungsten, which was administered as sodium tungstate to cows orally and by rumen fistula in daily doses of up to 6.6 mg per kg body weight. This effect of tungsten depends on the molybdenum content of the fodder and can be overcome in the case of high molybdenum levels. The relationship between the nitrate intake of the animal, the dose of tungsten administered to the animal daily and the highest concentration of nitrite reached in the rumen is given as a mathematical equation as well as in the form of a triangular diagram. By means of this three-element relationship and as a result of kinetic studies on the action of tungsten, a dosage pattern of tungsten was elaborated. The effectiveness of tungsten as a protective against nitrate intoxication was proved on cows dosed repeatedly as well as with single doses of nitrate up to 500 mg NO3 per kg body weight. It is concluded finally that tungsten offers a high degree of protection against nitrate toxicity to ruminants. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The function of ascorbate with respect to prolyl 4-hydroxylase activity

1. Incubation in the presence of 2-oxoglutarate and oxygen inactivates prolyl 4-hydroxylase (prolyl-glycyl-peptide, 2-oxoglutarate:oxygen oxidoreductase, EC 1.14.11.2), with a t 1/2 of 80 s at 37 degrees C. This inactivation is not affected by the presence or absence of the prolyl peptide substrate or added Fe(II). 2. This inactivation can be prevented by either ascorbate or dithiothreitol. It can be reversed by dithiothreitol but not by ascorbate. 3. Although the iron-containing form of prolyl 4-hydroxylase requires ascorbate for activity, ascorbate is not stoicheiometrically consumed in the reaction catalysed by the enzyme. Ascorbate cannot be replaced by alloxan, lactate, NADH plus phenazine methosulphate, dithiothreitol or L-cysteine. 4. Ascorbate has a double function with respect to prolyl 4-hydroxylase activity. On the one hand, it is required to initiate the reaction when the enzyme has become oxidized during isolation. On the other hand it is required for the protection against inactivation induced by 2-oxoglutarate and oxygen, presumably by preventing S-S bridge formation. The latter function may be of physiological importance.

The number and localisation of adenine nucleotide-binding sites in beef-heart mitochondrial ATPase (F1) determined by photolabelling with 8-azido-ATP and 8-azido-ADP

1. When irradiated 8-azido-ATP becomes covalently bound (as the nitreno compound) to beef-heart mitochondrial ATPase (F1) as the triphosphate, either in the absence or presence of Mg2+, label covalently bound is not hydrolysed. 2. In the presence of Mg2+ the nitreno-ATP is bound to both the alpha and beta subunits, mainly (63%) to the alpha subunits. 3. After successive photolabelling of F1 with 8-azido-ATP (no Mg2+) and 8-azido-ADP (with Mg2+) 4 mol label is bound to F1, 2 mol to the alpha and 2 mol to the beta subunits. 4. When the order of photolabelling is reversed, much less 8-nitreno-ATP is bound to F1 previously labelled with 8-nitreno-ADP. It is concluded that binding to the alpha-subunits hinders binding to the beta subunits. 5. F1 that has been photolabelled with up to 4 mol label still contains 2 mol firmly bound adenine nucleotides per mol F1. 6. It is concluded that at least 6 sites for adenine nucleotides are present in isolated F1.

HLA antigens in cases of giant cell arteritis

HLA tissue-type antigen determination for A-, B- and C-antigens in 88 patients suffering from giant cell arteritis of the temporal artery showed no significant deviations as compared to a control material of 3164 blood donors. A weak indication of association with antigen HLA-B8 appeared to be of interest due to a corresponding indication in previous investigation. The patients were a mixed hospital material, consisting of cases of clinical temporal arteritis and patients with polymyalgia rheumatica. There was an overrepresentation of women (77%). Familial occurrence was demonstrated sporadically (3 pairs of siblings).

Nitrate poisoning in cattle. 4. The effect of nitrite dosing during parturition on the oxygen capacity of maternal blood and the oxygen supply to the unborn calf

In a series of experiments the effect of administering KNO2 was studied, during parturition, on the capability of oxygen transport of maternal blood and on oxygen transfer to foetal blood. The following blood parameters were analysed, MHb percentage, pO2, O2-saturation, pH, pCO2, and (NO2) in maternal arterial blood (carotid art.) and venous blood (jugular vein) and in foetal arterial blood (umbilical art.) and venous blood (umbilical vein). The relative O2-saturation was calculated from the estimated O2-saturation by multiplying with the factor Hb (mmol/l) minus MHb (mmol/l), divided by Hb (mmol/l). In addition, blood pressure in the carotid artery, heart rate, and respiration rate in the dam were continuously recorded for some hours. A dosage of 9 to 12 mg of NO1/kg body weight intravenously or of 30 mg of NO2/kg body weight orally to the dam caused much higher MHb percentages and NO2 contents in the maternal blood than in the foetal blood. In maternal blood the ratio of NO2 content to MHb percentage was proportional to that in foetal blood. In the arterial blood, MHb percentages were almost as high as in the venous blood. After administering of nitrite, relative O2-saturation dropped simultaneously with the increase in methaemoglobin. Nitrite treatment caused a drop in the maternal blood pressure; heart rate and respiration rate increased. O2-saturation in the blood in the umbilical vein was much lower in the animals with nitrite treatment than in those without. These experimental results show clearly that the oxygen capacity of the blood decreases after nitrite treatment. In pregnant cows the oxygen supply to the foetus will be adversely affected after nitrate intake, especially by the lower oxygen transfer via the placenta, though hardly at all by methaemoglobin formation in the foetal blood. When the oxygen transfer to the foetal blood decreases too sharply, intra-uterine death and ultimately abortion may result.

EEG observations in dystrophia myotonica (Curschmann-Steinert)

An investigation has been carried out in a group of 84 (+2) patients suffering from myotonic dystrophia (Curschmann-Steinert). Manual measurements show that in these patients: (1) the alpha rhythms have low frequencies, related to the age of the patient and to the duration and severity of the disease; (2) the alpha rhythms are regular, monotonous; (3) the alpha rhythms have small amplitudes; there appears to be no relation between alpha frequency and amplitude; (4) the alpha indices are high during eyes closed as well as during eyes open. The computer measurements generally appear to concur with the above and in addition show that the bilateral and longitudinal coherences are high, indicating considerable synchrony of the alpha rhythm over large areas on both sides of the head. The possible significance of these observations is discussed.

Properties of prolyl 4-hydroxylase containing firmly-bound iron

1. Prolyl 4-hydroxylase (prolyl-glycyl-peptide, 2-oxoglutarate:oxygen oxidoreductase, EC 1.14.11.2) was isolated in a form containing iron (0.85-1.1 mol Fe/mol enzyme). 2. The enzyme was pure according to gel electrophoresis and had a high specific activity (1.8-2.6 mumol . mi-1 . mg-1). 3. Experiments with metal chelators showed this iron to be firmly bound and to be required for catalytic activity. 4. According to EPR spectrometry the bound iron is not part of a [2Fe-2S] or a [4Fe-4S] cluster. 5. The enzyme activity is to a large extent independent of added Fe2+. 6. The enzyme activity is completely dependent on ascorbate. 7. In the absence of ascorbate but the presence of substrates the enzyme is irreversibly inactivated. 8. Continuous measurement of enzyme activity was possible by following oxygen uptake.

Nitrate poisoning in cattle. 5. The effect of tungsten on nitrate formation by rumen microbes

Sodium tungstate added to rumen fluid depressed the nitrate reductase activity of rumen microbes. The rate of nitrite formation in rumen fluid fell by about 86% if 20 mu mol of Na2WO4 were added per litre. At 100 and 500 mu mol/l no nitrite accumulation was observed. This inhibition was overcome by molybdenum. Experiments in cows confirmed these in vitro findings. Tungsten is suggested as a promising preventative of nitrite intoxication in ruminants. [For Part 3 see VB 50, abst. 5179.] (Abstract retrieved from CAB Abstracts by CABI’s permission)

Localisation of adenine nucleotide-binding sites on beef-heart mitochondrial ATPase by photolabelling with 8-azido-ADP and 8-azido-ATP

1. In addition to the previously studied 8-azido-ATP, 8-azido-ADP is a suitable photoaffinity label for beef-heart mitochondrial ATPase (F1). 2. Photolysis at 350 nm of 8-azido-ADP in the presence of isolated F1 leads to inactivation of ATPase activity. Both ATP and ADP (but not AMP) protect against the inactivation. 3. In the absence of Mg2+, 8-azido-ADP binds almost equally to the alpha and beta subunits of F1, whereas in the presence of Mg2+ the alpha subunits are predominantly labelled. 4. The ATPase activity is completely inhibited when two molecules of 8-azido-ADP are bound per molecule F1. 5. 8-Azido-ATP and ATP are competitive substrates for F1, indicating that in the presence of Mg2+ 8-azido-ATP binds to the same site as ATP. 6. The amount of tightly bound nucleotides in F1 is not significantly changed upon incubation with 8-azido-ATP either in the light or the dark. 7. 8-Azido-ATP is also a suitadrial particles, photolabelling leading to inactivation of ATPase activity. 9. Oxidative phosphorylation and the ATP-driven reduction of NAD+ by succinate are also inhibited by photolabelling Mg-ATP particles with 8-azido-ATP. 10. In contrast to the uncoupled ATPase activity, where the two ATP-binding sites do not interact, cooperation between the two sites is required for ATP hydrolysis coupled to reduction of NAD+ by succinate.

Inhibition of human neutrophil migration by aggregated gammaglobulin

Heat-aggregated human gammaglobulin has been shown to inhibit the random migration of human neutrophils in serum-containing medium. This inhibition was not due to metabolic exhaustion or deactivation of the cells, since migration in the presence of aggregated gammaglobulin and casein as a chemotactic stimulus was not inhibited. The inhibition of migration was not mediated by a negative chemotactic gradient produced as a result of complement activation, and could be demonstrated in complement-depleted serum. Sera obtained from patients with rheumatoid arthritis with evidence of circulating immune complexes were able to significantly inhibit neutrophil migration, indicating that this phenomenon may be a useful means for the detection of circulating immune complexes. It is suggested that aggregated gammaglobulin or immune complexes can inhibit the chemokinetic effect of serum on neutrophils by a reversible interaction with the neutrophil surface, and that this inhibition could contribute to the accumulation of neutrophils at sites of immune complex deposition in vivo.

The crude protein production of grassland and the utilization by milking cows

An attempt was made with experimental data of various origins to quantify the intake of N from pasture grass by milking cows during the grazing period. It was also demonstrated how much of this N was removed by secretion in the milk as well as the conc. of N in the faeces and in the urine remaining on the pasture after grazing. From a fertilizer application to the pasture of 450 kg N/ha yr an equal conc. was taken up by the herbage. Of this herbage N about 75-80% remained on the pasture after grazing. The conc. remaining on the grassland increased sharply with increasing N rates and this went parallel with an increasing intensity in the N circulation in the system soil-plant-animal-soil and a rising NO3 content in the surface layer of ground water. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Grassland farming and minerals in cattle

Data reported earlier by J.A. Keuning [Stikstof (1974) 76, 87] on the mineral composition of grass samples from intensively managed farms in the Netherlands in 1962-1971 are tabulated and discussed in relation to mineral requirements (K, Na, Cl, Ca, P and Mg) of grazing high-yielding dairy cows. The effect of N fertilizer on the nitrate content in grass and other roughages is also considered in relation to the origin and prevention of nitrate poisoning in cattle. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Brown-adipose-tissue mitochondria: photoaffinity labelling of the regulatory site of energy dissipation

Brown-adipose-tissue mitochondria possess an energy-dissipating ion uniport which is inhibited by purine nucleotides. The regulatory nucleotides bind to a high-affinity site on the outer face of the inner membrane which is independent of the adenine nucleotide translocator. A direct correlation between affinity for the regulatory site and ability to inhibit the ion uniport is demonstrated for a number of nucleotide analogues. 8-Azido-adenosine 5'-triphosphate, a photoaffinity label, also competes with GDP for the binding site and induces respiratory control. 8-Azido-adenosine [gamma-32P]triphosphate was prepared and covalently bound to hamster brown-adipose-tissue mitochondria by near-ultraviolet irradiation. Two major radioactive bands were identified of apparent molecular weight 30000 and 32000, representing 6% and 10% of the inner membrane protein respectively. Selective labelling enabled the 30000-Mr protein to be identified as the carboxyatractylate binding component of the adenine-nucleotide translocator and the 32000-Mr protein to be identified as the regulatory site of the energy-dissipating ion uniport. The levels of the 32000-Mr protein in the inner membrane of guinea-pig brown-adipose-tissue mitochondria correlate with the degree of thermogenic adaptation of the animal.

Specific photolabelling of beef-heart mitochondrial ATPase by 8-azido-ATP

1. 8-Azido-ATP is a suitable photoaffinity label for beef-heart mitochondrial ATPase (F1) 2. 8-Azido-ATP is hydrolysed slowly by F1 in the dark. Photolysis at 350 nm in the presence of F1 leads to inhibition of the ATPase activity. The presence of ATP during illumination prevents the inhibition. Illumination of F1 in the absence of 8-azido-ATP causes no inhibition. 3. Added Mg2+ is not necessary for the binding of the 8-azido-ATP to F1. 4. 8-Azido-ATP binds specifically to the beta subunits of F1. 5. The ATPase activity is completely inhibited when 2 mol of 8-azido-ATP are bound per mol F1.

Monozygotic twins with temporal arteritis and ophthalmic arteritis

Temporal arteritis - ophthalmic arteritis occurring in a pair of monozygotic twins, who were 72 and 77 years of age respectively at the onset of symptoms, is reported. It is pointed out that it is rare to see, as in the first case, an improvement in an already existing severely reduced vision, in relation to corticosteroid treatment. The importance of genetic factors in temporal arteritis is discussed; further it is suggested that a possible association of the disease with tissue type antigens be the object of further study.