Blood pressure and erythrocyte Na+ transport systems in a French urban male population

This paper reports an investigation of blood pressure (taken as a continuous variable) as a function of: erythrocyte Na+ content; Na+,K+ pump; Na+,K+ cotransport and Na+,Li+ countertransport fluxes, and passive cation permeabilities in fresh erythrocytes from 129 French males who were living in an urban area and were not under treatment for any medical condition (after allowing for the effects of age, body mass index, alcohol and tobacco consumption). In contrast with previous findings in a North American population, we were unable to confirm that blood pressure was correlated with erythrocyte Na+ content and Na+,K+-AT-Pase activity. Conversely, the only transport parameter correlated (negatively) with blood pressure was outward Na+,K+ cotransport [r = -0.20, P less than 0.05 and r = -0.19, P less than 0.05, for systolic (SAP) and diastolic arterial pressure (DAP), respectively; n = 114]. When allowing for age, body mass index and alcohol consumption, the correlation coefficient between the Na+,K+ cotransport system and blood pressure increased from -0.20 to -0.28 (P less than 0.01) for SAP and from -0.19 to -0.28 (P less than 0.01) for DAP (n = 105). We conclude that the correlations between blood pressure and erythrocyte Na+ transport function could differ between North American and French (or Mediterranean) populations. In any case, a decreased pump or outward Na+,K+ cotransport activity may lead hypertensive subjects to a similar increase in cell Na+ (and Ca2+) content in the vascular wall.

Influence of membrane sodium transport upon the relation between blood lead and blood pressure in a general male population

Five red blood cell cation transport systems (RBCTS), together with blood lead level and blood pressure, were measured in 129 male adult subjects who were not occupationally exposed to lead or subsequent to a course of treatment for hypertension. Blood lead was positively related with systolic blood pressure, and to a lesser degree with diastolic blood pressure. Blood lead was found significantly negatively related to one of the RBCTS, Na+,K+ cotransport, and in addition, Na+,K+ cotransport appeared negatively related to blood pressure. Final results showed that blood lead no longer accounts for an increase in systolic blood pressure when Na+,K+ cotransport was taken into account; the same trend was observed with diastolic blood pressure. These findings suggest that a blood lead-related Na+,K+ cotransport impairment could explain the blood pressure increase observed to parallel the blood lead increase.

Possible relationship between the restricted biological function of rat T kininogen (thiostatin) and its behaviour as an acute phase reactant

Studies on biological properties of rat T kininogen have shown that the role of this peculiar kininogen so far specific to the rat probably differs significantly from that of other low molecular mass kininogens. In particular the kinin precursor function has been either lost or considerably reduced as a result of structural modifications during evolution. The calpain inhibiting function demonstrated for other low and high molecular mass kininogens has also probably disappeared from T kininogen, and since T genes do not allow the synthesis of high molecular mass kininogens [Kitagawa et al. (1987) J. Biol. Chem. 262, 2190-2198], the procoagulant function devoted to the light chain of high molecular mass kininogen has also been lost by T genes products. The only remaining function of rat T kininogen would be therefore that of a lysosomal cysteine proteinase inhibitor which is expressed either by the native molecule or by proteolytic products which appear to be more easily released than vasoactive peptides. Such a specialization for a given function could be related to the behaviour of T kininogen as an acute phase reactant, the dramatic changes in concentration of which could at the same time serve certain functions and be damageable for others.

Cysteine-proteinase-inhibiting function of T kininogen and of its proteolytic fragments

Previous attempts to liberate T kinin from T kininogen [Moreau et al. (1986) Eur. J. Biochem. 159, 341-346; Gutman et al. (1988) Eur. J. Biochem. 171, 577-582] have shown that complete fragmentation of the precursor molecule into inhibitory peptides was achieved before any vasoactive peptide was released, suggesting a possible physiological significance for this phenomenon. In this study, cysteine-proteinase-inhibiting properties of rat T kininogen and of its proteolytic fragments issuing from trypsin and submaxillary gland endopeptidase k hydrolysis, have been investigated using rat lysosomal cathepsins B, H and L, papain and bovine calpains I and II. All three lysosomal cathepsins were inhibited by T kininogen but tighter interactions were observed with cathepsin L and papain. Though higher Ki values were obtained for cathepsins B and H, rate constants for association were found to have high and almost similar values (in the 10(6) M-1 s-1 range) whatever the enzyme used. Proteolytic fragments also inhibited cathepsin L and papain very strongly and even better than the entire molecule for some of them, but no significant inhibition of cathepsins B and H was observed. Bovine calpains were not inhibited by T kininogen nor by its proteolytic fragments. From the results of this kinetic analysis, which indicates that both the association and the dissociation of lysosomal cysteine proteinases with T kininogen may occur rapidly, an hypothesis has been put forward on the possible in vivo functioning of T kininogen as a proteinase inhibitor.

T-kinin release from T-kininogen by rat-submaxillary-gland endopeptidase K

Submaxillary gland extracts have been fractionated to characterize the enzyme responsible for the T-kininogenase activity previously reported in this tissue [Damas, J. & Adam, A. (1985) Mol. Physiol 8, 307-316] and to know whether this activity could be of physiological relevance, since no enzyme reacting in catalytic amounts has been described so far to be able to release a vasoactive peptide from T-kininogen. The purified enzyme, provisionally called endopeptidase K, has an apparent Mr of 27,000 when not reduced prior to analysis but 21,000 after reduction and an acidic pI of 4.3 +/- 0.1. Antigenically, it is not related to tissue kallikrein. Upon incubation with purified T-kininogen it may induce a complete liberation of T-kinin from the precursor provided it is added in stoichiometric amounts. However, in parallel with the liberation of immunoreactive kinin, a proteolysis of T-kininogen is observed which is not restricted to the site of insertion of T-kinin as would be expected using a specific kininogenase. In agreement with these results, no change of the mean blood pressure was observed upon injection of endopeptidase K into the circulation of normal rats even if the amount of injected enzyme was up to ten times that required for tissue kallikrein to induce a significant fall in blood pressure. However, in spite of the large proteolysis induced by incubation with stoichiometric amounts of endopeptidase K, the total papain inhibiting capacity of T-kininogen as well as the value of the apparent inhibition constant, Ki, with this proteinase remained unchanged. Proteolytic fragments which retain cysteine-proteinase-inhibiting activity may therefore be released from T-kininogen by endopeptidase K more easily than immunoreactive kinin, thus emphasizing a prominent function of proteinase inhibitor or of proteinase inhibitor precursor for this molecule.

Auditory-visual equivalence by mentally retarded and intellectually average older children

Auditory-visual information equivalence in 15 mentally retarded and 15 intellectually average 12- to 13-year-old children were compared using nine matching tasks. Intellectually average subjects were more accurate on both intra- and intersensory tasks. Retarded subjects were more accurate on intra- than on intersensory tasks, whereas there was no such difference for the average subjects. Tasks involving transposition were more difficult for the retarded children than those not involving transposition. The intellectually average children behaved similarly on intrasensory tasks but on intersensory tasks were more accurate when transposition was involved. There was no association between IQ and intra- or intersensory performance when data from the two groups were examined separately.

Relationship between the cysteine-proteinase-inhibitory function of rat T kininogen and the release of immunoreactive kinin upon trypsin treatment

The potential kininogenic function of rat T kininogen has been studied in parallel with the cysteine-proteinase-inhibitory function also carried by this molecule. Proteolytic cleavage of the molecule was observed upon incubation with catalytic amounts of trypsin. These conditions do not permit any significant release of immunoreactive kinin and do not modify the total papain-inhibiting capacity of T kininogen. As trypsin concentration increases in the reaction mixture, immunoreactive kinin is liberated and the total papain-inhibiting capacity decreases accordingly, as indicated by titration studies. This decrease, however, does not exceed 50% of the initial value even at a trypsin concentration as high as 75 microM, indicating that only one of the two inhibitory sites has been inactivated. The remaining inhibitory fragment corresponds to a peptide of apparent Mr 24 000, which binds papain at least as well as native T kininogen. T kininogen, therefore, appears as a potent proteinase inhibitor and/or a proteinase inhibitor precursor, whereas its kininogenic function remains questionable since no specific kininogenase able to release T kinin or another kinin under physiologically compatible conditions has been found so far.

Prenatal exposure to lead and cadmium and psychomotor development of the child at 6 years

In 1977, a hair sample was taken from 26 newborn babies and their mothers and analysed for lead and cadmium. Six years later, each of these 26 children was given a psychometric test (McCarthy Scales of Children's Abilities). Statistical analysis shows a significant negative relationship between the degree of in utero exposure to cadmium and lead and the child's motor and perceptual abilities. Any effect on memory or verbal skills was not statistically significant. Allowing for the confounding variables does not consistently affect these results.

[Estimation of the hazards ratio in two grouped samples]

A simple estimator of the hazards ratio of two grouped samples is proposed. If the number of time grouping intervals is fixed, the following asymptotics hold: unbiasedness, and full efficiency when the true hazards ratio is 1 and the probability of failure in each interval is small. Under the latter condition, the estimator is equivalent to "MHP" estimator (Mantel-Haenszel estimator for a Poisson model). Simulations show that this estimator performs better than others when grouping is coarse. An asymptotically unbiased estimator of its variance is proposed.

Effect of blood storage on lymphocyte subpopulations

In the evaluation of helper and suppressor T lymphocyte subpopulations testing of the cells may not be carried out until the day following collection of the blood. The possibility that changes occur during overnight storage at 4 degrees C or 22 degrees C has been investigated. No statistical differences in percentages of helper and suppressor T cells between fresh samples and overnight stored samples were found if the blood was kept at 22 degrees C.

Blood cadmium levels in a general male population with special reference to smoking

Blood-cadmium (Cd-B) level, blood pressure, and several biological parameters in blood were measured in 440 men who were not occupationally exposed to cadmium and who had a detailed smoking history. No significant correlation was found between Cd-B and blood pressure. Among biological parameters, those known to be related to smoking appeared significantly correlated with Cd-B. Analysis of smoking history showed that Cd-B is strongly elevated in current smokers, with a dose-effect relationship between daily consumption of tobacco and Cd-B; moreover, exsmokers had significantly higher Cd-B than nonsmokers. This finding shows that Cd-B partly reflects past exposure to cadmium.

[Stage I malignant melanoma of the skin. Prognostic value of thickness and level (author's transl)]

In a retrospective study of 95 patients seen between 1950 and 1978, the outcome of malignant melanoma levels III, IV and V of Clark's classification was reviewed. Patients with lentigo malignant melanoma were excluded. The overall survival rate was 63% at 5 years and 48% at 10 years. For the whole population of patients significant differences in survival rate were associated with level (p = 0,00002), thickness (less than 2 mm or greater than or equal to 2 mm; p less than 0.0,0001) and histological type (p = 0,02). The significance of prognostic variables taken separately was calculated by the Breslow method and was found to be: p = 0,0005 for thickness, p = 0,0009 for patient's age and p = 0,02 for histological type. In analysis with two variables, including level, thickness was the variable that added most to the information on prognosis supplied by level. For the population of patients with melanoma levels III and IV significant differences in survival rate were associated with thickness (less than 2 mm or greater than or equal to 2 mm; p less than 0,001), though not with level. When the variables were studied separately, thickness and patient's age were significant (p = 0,02 and p = 0,03 respectively). Analysis with two variables, including thickness, showed that age was the variable that added most to the information on prognosis supplied by thickness.

[An application of Mantel's test to the analysis of some biological assays (author's transl)]

By analogy with the problem of comparing two survival curves, Mantel's test is used to compare two dose-response curves, each obtained as a result of testing the same subjects at different dose levels. An application to blood platelet aggregation in two groups of subjects is given.

Lateral differences in habituation of ipsilateral head-turning to repeated tactile stimulation in the human newborn

Lateral differences in habituation of ipsilateral head-turning to repeated tactile perioral stimulation following midline head restriction was studied in 44 full-term neonates. Left-sided stimulation had a significantly greater and faster decremental effect than right-sided stimulation. Even in the absence of tactile stimulation (Control Group), head-turning to the left decreased systematically whereas head-turning to the right did not. The transient efficacy of prior midline head restriction for the elimination of lateral differences in both spontaneous head movements and responsiveness to tactile input suggests that behavioral asymmetry is already well-established in the newborn.

Intra- and inter-modal effects of prior stimulation on cardiac responsiveness to repeated stimulation in the human newborn

The effect of prior equivalent auditory and somesthetic input on cardiac acceleration responses to repeated auditory and somesthetic stimulation was studied in 56 healthy 2- or 3-day-old infants. Responsiveness to initial presentation of the reiterative auditory stimulus was significantly greater than to the reiterative somesthetic stimulus regardless of the modality stimulated during the preceding series. In contrast the course of response decrement to subsequent repeated presentations of both stimuli was significantly more rapid when the reiterative and prior stimuli were in different modalities (inter-modal) than when they were in the same modality (intra-modal). The findings demonstrate a modality difference in effect of anticedent input on initial responiveness and a greater efficacy of inter- than of intra-modal auditory and somesthetic stimulation for the habituation of neonatal cardiac responses to repeated stimulation.

Modality differences in the habituation and dishabituation of cardiac responsiveness in the human newborn

The relative efficacy of (1) repeated auditory and somesthetic stimulation for the habituation of cardiac acceleration responses and (2) intramodal and cross-modal stimulation for the dishabituation of cardiac responses was studied in 45 full-term 2-day-old infants. Although the stimuli were equally effective initially, repeated presentation of the somesthetic stimulus had a greater decremental effect than repeated presentation of the auditory stimulus. The stimuli were equally effective in producing dishabituation when in a different modality from that of the habituating stimulus (cross-modal) but not when in the same modality (intramodal). Changes in the locus of stimulation without a change in modality were ineffective for producing dishabituation. The findings indicate the human newborn discriminates auditory and somesthetic inputs effectively and equally but does not discriminate contralateral from ipsilateral stimulation in either modality.