Nakai & Chi Le (1970) have described a rapid method for the determination of the N content of bovine milk based on the close correlation of absorbance at 280 nm with values for total N as determined by the Kjeldahl procedure. The applicability of the method to human milk samples has been investigated. The procedure is limited by: (1) the dependence of the relation between absorbance value and N content on both the mode of collection and the postnatal age of the donor, and (2) variable interference by non-protein components of the milk. In spite of these shortcomings, the method may be of value as a screening test for certain human milk banks.

Animals↗

PubMed1983

Metabolic and endocrine consequences of depriving preterm infants of enteral nutrition.

Plasma enteroglucagon, pancreatic polypeptide, gastrin, motilin, neurotensin, gastric inhibitory polypeptide, secretin, vasoactive intestinal peptide and blood glucose, alanine, ketone bodies, lactate and pyruvate were measured on the sixth postnatal day in (a) a group of 10 preterm infants who on account of hyaline membrane disease had not received enteral feeding since birth and (b) before and at 55, 90, and 120 minutes after feeding in a group of healthy preterm infants fed three-hourly on human milk. Gut hormones were also measured in umbilical venous cord blood. The infants receiving regular boluses of milk from birth demonstrated postnatal surges in preprandial concentrations of gut hormones together with cyclical hormonal responses to feeding. None of these changes were seen in infants receiving intravenous fluids. The latter infants also had lower concentrations of blood alanine, glycerol and hydroxybutyrate and lacked the phasic changes in intermediary metabolites seen in the infants receiving enteral boluses of milk. Thus deprivation of enteral feeding results in a profound alteration of the metabolic and endocrine milieu which may have important effect on the process of adaptation to postnatal life.

Hormones↗

PubMed1983

Growth hormone response to feeding in term and preterm neonates.

Plasma growth hormone concentrations were measured in 248 healthy term and preterm infants. At birth growth hormone concentrations in cord blood from both term and preterm babies were approximately 100-fold higher than those in blood drawn from healthy adults. By the sixth postnatal day basal pre-feed levels had fallen in term neonates by 65% and a marked postprandial rise was apparent; preterm infants did not show this initial fall in preprandial hormone levels nor was any response to feeding seen. However a fall in preprandial concentrations accompanied by the development of postprandial surges in growth hormone occurred during the next 2 weeks so that by 24 days the postprandial rise was similar to that of term neonates on the sixth day. We conclude that although the initial postnatal changes in plasma growth hormone concentrations are different in preterm and term infants, feeding is a major stimulus to growth hormone secretion in both groups of neonates. Further work is needed to define the precise role of this hormone in neonatal metabolic adaptation.

Growth Hormone↗

PubMed1983

Immunoglobulin concentrations and bacterial antibody titres in breast milk from mothers of 'preterm' and 'term' infants.

IgA, IgM and IgG concentrations and their bacterial antibodies to E. coli, group B streptococci and Brucella abortus were measured in human breast milk collected from the 1st to 10th day post-partum from mothers delivered of 'preterm' infants (Premature Breast Milk or PBM) and from mothers delivered of term infants (Term Breast Milk or TBM). Reverse passive haemagglutination tests (RPH), rocket immuno-electrophoresis and mixed reverse passive antiglobulin haemagglutination tests (MRPAH) were employed. PBM at 2-5 days post-partum (though not beyond this period) contained higher IgA levels than did TBM, and this difference persisted even when total IgA was expressed as a proportion of total milk protein: in contrast the IgM and IgG contents of PBM and TBM were the same at both these postnatal ages. The titre of IgA antibody to E. coli, which was absorbable only by the corresponding bacteria, showed no significant difference between PBM and TBM, whereas the titres of IgA reacting with Br. abortus and, to a lesser extent group B streptococci, were higher in PBM than those in TBM. However the IgA which reacted with Br. abortus and group B streptococci was not specific to those organisms but was absorbed by all three bacteria studied. It is speculated that the high IgA content of early preterm milk and perhaps the presence of especially high titres of what appears to be a non-specific or cross-reacting bacterial IgA in such milk, may be immunologically advantageous to low birthweight infants fed on their own mother's milk.

Antibodies, Bacterial↗

PubMed1982

Maximum oxygen consumption and catecholamines in thyroidectomized dogs.

Comparisons have been made in 7 dogs between maximum oxygen consumption recorded before (N dogs) and after thyroidectomy (T dogs). The comparisons were performed under two conditions 1) during severe cold stress (CVo2 max), 2) during a short period of exhaustive work (Ex Vo2 max). Heart rate, plasma catecholamine and substrate concentrations (glucose, lactic acid, FFA) were measured under each condition. 1. Thyroidectomy induced a more substantial decrease in CVo2 max than in Ex Vo2 max. 2. At CVo2 max, average plasma epinephrine and norepinephrine concentrations rose to a higher level in T dogs than in N dogs. In T dogs, correlations were found between plasma epinephrine concentrations and CVo2 max values, and between plasma norepinephrine concentrations and CVo2 max values. At Ex Vo2 max, average plasma norepinephrine concentrations were similar in N dogs and in T dogs, and average plasma epinephrine concentrations were not significantly different from each other. 3. At Ex Vo2 max, average plasma concentrations of the various substrates were not significantly different in N dogs and T dogs. At CVo2 max, plasma FFA levels were higher in T dogs. It may be concluded that in dogs, thyroidectomy affects mechanisms which are more specifically involved in heat production than in muscular exercise. The increased catecholamine secretion in response to cold which occurred in T dogs appeared merely to limit the decrease in heat production. It seems possible that increased catecholamine secretion compensates for the decreased sensitivity of beta receptors to catecholamine but it cannot fully account for the effects of thyroidectomy.

Animals↗

PubMed1982

IgA amd preterm milk.

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Female↗

PubMed1982

Human milk banks.

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Female↗

PubMed1982

The relation of idiotype expression to isotype and allotype in the anti-p-azobenzenearsonate response.

The distribution of idiotype-positive plaques in mice of various strains injected with T-independent (TI) and T-dependent conjugates of p-azobenzenearsonate (Ars) has been investigated. With maturation of the responses there is a progressive loss of dominance of the major cross-reactive idiotype (CRI) in A/J and C.AL-20 mice. The extremes are represented by the predominantly CRI+ IgM plaque response to a single injection of the TI antigen, Ars-coupled Brucella organisms (Ars-Br), and the low frequency of CRI+ plaques in the polyisotypic response elicited by Ars-KLH (keyhole limpet hemocyanin) in adjuvant. The secondary response to Ars-Br was characterized by an intermediate display of idiotype-positive plaques in IgM, the IgG subclasses and IgA. Detailed analyses of the distribution of CRI+ plaques between isotypes in 60 mice hyperimmunized with Ars-KLH revealed that the expression of idiotype in any of the IgG subclasses and IgA was constant and independent. This is interpreted to indicate random assembly of VH with C gamma and C alpha genes during the switch. BALB/c and C3H mice also express a predominant idiotype during primary and secondary responses to Ars-Br as detected by our heterologous anti-A/J CRI serum. These strains only very rarely maintain the idiotype after hyperimmunization with Ars-KLH. We conclude that hyperimmune responses which probably involve multiple modes of regulation give a poor indication of the germ-line V gene repertoire.

Animals↗

PubMed1982

Vasoactive intestinal peptide (VIP) in preterm and term neonates.

There is a little information on vasoactive intestinal peptide (VIP) in the neonatal period. We have measured plasma concentrations of this biologically important peptide in 159 preterm infants and 98 term neonates. Preterm neonates during the first four days of life had plasma VIP concentrations which were five times greater than the levels in 12 healthy adult controls (9.6+/-0.7 pmol/l, mean +/-S.E.M., compared with 1.9+/-0.5 pmol/l, p less than 0.001), and these elevated concentrations persisted throughout the neonatal period. In contrast term infants on the sixth day of life, had plasma VIP concentrations only half those seen in preterm infants on the same post natal age (p less than 0.001). Bottle-fed term infants had higher VIP levels than those who were breast fed (5.6+/-0.4 vs. 4.3+/-0,4, p less than 0.05). Plasma VIP concentrations did not change following a feed in any of the groups of neonates studied. The high plasma levels of VIP described may indicate a reduced neuropeptide clearance mechanism in neonates or alternatively, suggest a hitherto unrecognised role for this peptide hormone in the neonatal period.

Adult↗

PubMed1982

Postnatal surges in plasma gut hormones in term and preterm infants.

Using sensitive radioimmunoassays we have measured and compared plasma concentrations of motilin, gastrin, enteroglucagon, neurotensin, gastric inhibitory polypeptide and pancreatic polypeptide in (a) 53 healthy, preterm infants at birth or preprandially at 2.5, 6, 13 or 24 days; (b) 45 normal, breast-fed, term infants at birth or preprandially at 6 or 16 days, and (c) 12 healthy fasting adults. Plasma concentrations of all six hormones rose during the neonatal period in both preterm and term infants, the first four of these hormones reaching levels which exceeded those seen in healthy fasting adults. The rate of increase and the magnitude of the changes were less in term infants than preterm infants. These changes in plasma hormone concentrations may be the result of enteral feeding. Gut hormones exert important effects on gut growth, secretion and motility and on intermediary metabolism, and the postnatal hormonal surges observed may play a key role in the postnatal adaptions to enteral feeding.

Aging↗

PubMed1982

Expression of the major cross-reactive idiotype in a primary anti-azobenzenearsonate response.

We have studied the occurrence of IgM plaque-forming cells secreting the cross-reactive idiotype (CRI) characteristic of the anti-azobenzenearsonate antibody responses in individual mice of different strains after one injection of the T-independent antigen, p-azobenzenearsonate-Brucella. Under these conditions of stimulation we find that idiotype is not unique to the Igh-1e and Igh-1d allotypes, but is expressed prominently in Igh-1a and Igh-1j strains and to a lesser but significant extent in Igh-1c and Igh-1b strains. We confirmed previous work that idiotype expression in mice hyperimmunized with protein conjugates of azobenzenearsonate is mainly restricted to mice of the Igh-1e allotype, but we find the display to be less marked than in mice given a single injection of the Brucella conjugate. We conclude that the B cell repertoire is inadequately revealed by analysis of serum antibodies of hyperimmune mice. We suggest the apparent correlation of the anti-azobenzenearsonate idiotype to allotype may be influenced by the activity of heavy chain regulatory genes, rather than the presence or absence of structural genes coding for the major CRI. We cannot exclude the possibility that the previously designated CRI-negative strains may express a cross-reactive determinant that is not necessarily a product of the CRI gene family.

Animals↗