Acceleration of the absorption of unchanged globulin in the new-born calf by factors in colostrum

Colostrum insulin supplementation does not influence immunoglobulin G absorption in neonatal Holstein bulls

Since insulin has been demonstrated to suppress IgG absorption in other neonatal species, we had the objective to delineate how colostral insulin concentrations affect IgG absorption in neonatal bovines. We enrolled Holstein bull calves (n = 48; body weight = 46.3 ± 0.84 kg) at birth and randomized them by birth order to receive (1) colostrum that contained basal insulin concentrations (12.9 μg/L; n = 16), or colostrum that had been supplemented with an exogenous insulin to increase the insulin concentration to either (2) 5 times (70.0 μg/L; n = 16) or (3) 10 times (149.7 μg/L; n = 16) that of the basal colostrum. Gross colostrum composition (crude fat: 4.1 ± 0.06%; crude protein: 11.7 ± 0.05%; lactose: 1.9 ± 0.01%; IgG: 63.9 ± 1.19 g/L) was similar between treatments and calves were fed (7% body weight, 3.1 ± 0.06 L) their treatments at 2, 14, and 26 h postnatal. Serum was collected at 0, 30, 60, 90, 120, 180, 240, 360, 480, and 600 min postprandial respective to the first and second colostrum feeding and analyzed for IgG concentration. The incremental area under the curve (I-AUC) and apparent efficiency of absorption (AEA) were calculated for the 10-h periods following the first and second colostrum meal. Serum IgG concentrations over time, I-AUC, and AEA were statistically analyzed as a complete randomized design. Colostrum insulin concentration did not affect serum IgG concentrations or the I-AUC or AEA after calves were fed colostrum at 2 and 14 h postnatal. High colostral insulin content is not detrimental or promotive to IgG absorption in neonatal Holstein bulls.

Enhancing Skin Health: By Oral Administration of Natural Compounds and Minerals with Implications to the Dermal Microbiome

The history of cosmetics goes back to early Egyptian times for hygiene and health benefits while the history of topical applications that provide a medicinal treatment to combat dermal aging is relatively new. For example, the term cosmeceutical was first coined by Albert Kligman in 1984 to describe topical products that afford both cosmetic and therapeutic benefits. However, beauty comes from the inside. Therefore, for some time scientists have considered how nutrition reflects healthy skin and the aging process. The more recent link between nutrition and skin aging began in earnest around the year 2000 with the demonstrated increase in peer-reviewed scientific journal reports on this topic that included biochemical and molecular mechanisms of action. Thus, the application of: (a) topical administration from outside into the skin and (b) inside by oral consumption of nutritionals to the outer skin layers is now common place and many journal reports exhibit significant improvement for both on a variety of dermal parameters. Therefore, this review covers, where applicable, the history, chemical structure, and sources such as biological and biomedical properties in the skin along with animal and clinical data on the oral applications of: (a) collagen, (b) ceramide, (c) β-carotene, (d) astaxanthin, (e) coenzyme Q10, (f) colostrum, (g) zinc, and (h) selenium in their mode of action or function in improving dermal health by various quantified endpoints. Lastly, the importance of the human skin microbiome is briefly discussed in reference to the genomics, measurement, and factors influencing its expression and how it may alter the immune system, various dermal disorders, and potentially be involved in chemoprevention.

Effect of delaying colostrum feeding on passive transfer and intestinal bacterial colonization in neonatal male Holstein calves

The objective of this study was to investigate the effect of time of first colostrum feeding on the passive transfer of IgG and on bacterial colonization in the intestine of neonatal dairy calves. Twenty-seven male Holstein calves were randomly assigned to 1 of 3 treatments at birth: calves were fed colostrum at 45 min (0 h, n = 9), 6 h (n = 9), or 12 h after birth (n = 9). Calves were fed pooled, heat-treated colostrum (62 g of IgG/L) at their respective feeding times at 7.5% of birth body weight and fed milk replacer at 2.5% of birth body weight per meal every 6 h thereafter. Blood samples were taken every 3 h using a jugular catheter and were analyzed for determination of serum IgG by radial immunodiffusion. At 51 h after birth, calves were euthanized for collection of tissue and digesta of the distal jejunum, ileum, and colon. Quantitative real-time PCR was used to estimate the prevalence of Bifidobacterium spp., Lactobacillus spp., Fecalibacterium prausnitzii, Clostridium cluster XIVa, and total Escherichia coli. Delaying colostrum feeding by 6 h (35.6 ± 1.88%) and 12 h (35.1 ± 3.15%) decreased the maximum apparent efficiency of absorption of IgG compared with feeding colostrum immediately after birth (51.8 ± 4.18%) and delayed the time to maximum serum IgG concentration (24 h vs. 15 h, respectively). Moreover, 12-h calves tended to have a lower prevalence of Bifidobacterium spp. (0.12 ± 0.017%) and Lactobacillus spp. (0.07 ± 0.019%) associated with the colon mucosa compared with 0-h calves (1.24 ± 0.648% and 0.26 ± 0.075%, respectively). In addition, 6-h (0.26 ± 0.124%) and 12-h (0.49 ± 0.233%) calves had a lower prevalence of total E. coli associated with ileum mucosa compared with 0-h calves (1.20 ± 0.458%). These findings suggest that delaying colostrum feeding within 12 h of life decreases the passive transfer of IgG and may delay the colonization of bacteria in the intestine, possibly leaving the calf vulnerable to infections during the preweaning period.

Increased colostral somatic cell counts reduce pre-weaning calf immunity, health and growth

Our objective was to study the relationships between colostral somatic cell counts (SCC, a criterion for mastitis severity at parturition) and early calf growth, blood indicators of immunity, and pre-weaning faecal and health states. Sixty-nine Holstein cows were assigned to three groups of greater (n = 21, 5051 × 10(3)), medium (n = 38, 2138 × 10(3)) and lower (n = 10, 960 × 10(3)) colostral SCC (per ml) in a completely randomized design. Calves received 2 l of colostrum on day 1, and jugular blood was sampled at birth, at 3 h after the first colostrum feeding and at 42 days of age for immunoglobulin G (IgG) measurements. Calves were fed transition milk from their dams until 3 days of age and whole milk from 4 to 60 days of age twice daily at 10% of body weight. Health status and faecal physical scores were recorded daily for 42 days. Increased colostral SCC was associated with increased serum IgG at parturition. Colostral pH increased and fat percentage decreased linearly with the rising SCC. Feeding colostrum with greater SCC was associated with reduced serum IgG concentrations at 3 h after first colostrum feeding, greater incidences of diarrhoea and compromised health status during the first 42 days of age, and reduced weaning weight gain, but had no effects on calf body length and withers height. Colostral volume and percentages of protein, lactose, solids-non-fat, total solids and IgG were comparable among groups. Results suggest a role for SCC, as an indicator of mastitis and colostral health quality, in affecting calf health. As a result of the novelty of calf health dependence on colostral SCC found, future studies to further characterize such relationships and to uncover or rule out possible mediators are required before colostral SCC could be recommended for routine on-farm use in managing dry cow and calf production.

An immunoelectron microscopic investigation of colostral IgG absorption across the intestine of newborn calves

The protein A-gold was used to examine the transport of colostral IgG from the lumen of the gut to the circulation in four newborn calves and one 24-hour-old calf. The absorptive enterocytes of the duodenum, jejunum and ileum were investigated five to 60 minutes after administering colostrum, and 24 hours after birth. In the newborn calves, an intracellular micropinocytotic transport of IgG molecules was dominant throughout the entire small intestine. The amount transported increased from the duodenum to the ileum. In addition, evidence of a selective, receptor-mediated transport of IgG during the first few hours of life was provided by the presence of bovine clathrin at the microvillous membrane of the duodenal and jejunal enterocytes, indicating the existence of specialised vesicles for transport, the so-called 'coated' vesicles. No sign of paracellular transport was detected. Intestinal closure was interpreted as a multifactorial event comprising the replacement of the fetal intestinal epithelial cells by more mature populations, the initial cessation of transport at the basal and lateral cell membrane of the absorptive enterocytes, and an increase in intracellular proteolytic activity by lysosomes.

Intestinal absorption of immunologically intact macromolecules in germfree colostrum-deprived piglets maintained on total parenteral nutrition

We have compared the neonatal absorption of anti-bovine gamma-globulin (BGG) antibody supplied in colostrum or saline in three groups of piglets born and maintained under different environmental conditions to determine the effect of these conditions on the cessation of intestinal absorption of macromolecules (anti-BGG antibody), termed "closure." An enzyme-linked immunosorbent assay was used to estimate the concentration of anti-BGG antibody in sera from each group of piglets. Three stages of macromolecular absorption through the piglet's intestine could be detected. The first stage is a nonselective massive absorption of macromolecules (in milligram levels) that lasts up to 3 days in germfree (GF) colostrum-deprived or conventional colostrum-fed piglets but up to 5 days in GF piglets maintained on total parenteral nutrition. In this stage, absorption was significantly (r = .05) higher in piglets fed anti-BGG serum with colostrum than in piglets fed anti-BGG serum without colostrum on GF day 0 (31.28% vs 15.59%) and GF-total parenteral nutrition day 3 (3.08% vs 0.11%). Thus, whenever there was the ability to absorb a massive amount of macromolecules, the sow colostrum had an enhancing affect. Although there was a minor effect of environmental or orally received stimuli in delaying closure, absorption of macromolecules decreased in all piglets maintained either parenterally or enterally after day 3. Thus, intestinal closure to massive absorption of macromolecules in piglets is primarily time (age)-dependent. The second stage is a selective absorption of immunoglobulins in much smaller quantities (microgram levels), inasmuch as absorption of 0.02% to 0.1% was determined in all 5-day-old piglets.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors in ruminant colostrum that influence cell growth and murine IgE antibody responses

Bovine colostrum was investigated as a source of biologically active molecules capable of stimulating the growth of mammalian cells in culture and modifying the immune response in a murine model. An extract prepared from bovine colostral whey by cation exchange and reversed-phase chromatography stimulated the growth of L6 rat myoblasts, Balb/c-3T3 mouse fibroblasts and BHK-21 baby hamster kidney cells with equal or greater potency than fetal bovine serum. Fractionation of the bovine colostral extract by gel-permeation chromatography in M-acetic acid identified a number of cell-growth factors for each cell type. Bovine colostral extract was compared with an ovine colostral whey preparation for its ability to modulate IgE antibody responses in mice. Doses of 8 and 4 mg/d of ovine colostral whey or bovine colostral extract specifically suppressed IgE antibody responses, whereas at lower doses suppression did not occur. We conclude that bovine colostrum contains cell-growth factors as well as immunomodulatory factors that are able to regulate the IgE response in a heterologous species.

Biological half-life of ovine antibody in neonatal lambs and adult sheep following passive immunization

Neonatal lambs and adult wethers were passively immunized with ovine antibody directed against ovalbumin or Brucella abortus. Estimates for the biological half-lives of the antibodies ranged from 18 to 24 days in neonatal lambs and 12 to 17 days in adult wethers. The evidence suggested that both normal and immunosuppressed wethers which were passively immunized with serum antibody catabolized this antibody at a faster rate than did neonatal lambs. The data provided no support for the hypothesis that the growth factors and immunomodulatory factors, which are known to be present in colostrum, can influence the biological half-life of homologous antibody following passive immunization.

Rotavirus and Cryptosporidium shedding in dairy calf feces and its relationship to colostrum immune transfer

Twenty Holstein calves received 2 L of colostrum twice within 12 h after birth; the first feeding occurred within 2 h of parturition. The increase in adsorption efficiency was related to the gamma globulin provided in the first colostrum feeding. Absorption efficiency ranged from 2.4 to 46.1%. The number of sheddings of rotavirus and Cryptosporidium by the calves during their first 4 wk of life was associated with serum gamma globulin concentration 24 h after birth and absorption efficiency. Absorption efficiency and body weight combined accounted for 60.4% of the variation in the number of sheddings; heavier calves shed more than lighter calves. During the first 4 wk, calves that shed more frequently gained less weight; weight gain was also associated with serum gamma globulin levels 24 h after birth. Colostrum composition varied between quarters of the same cow. Total protein and gamma globulin content of colostrum from the rear quarters was higher than from the front quarters. The association between number of sheddings and absorption efficiency suggest that calves should not be fed colostrum containing less than 9 g/100 ml of total protein.

Bovine enteric colibacillosis

In this article, the authors discusses procedures used to determine enteropathogenic strains of Escherichia coli, the history of the development of prophylactic procedures, including cow vaccination and specific monoclonal antibody, and other preventative measures with as proper management, nutrition, and sanitation.

Vaccination against enteric rota and coronaviruses in cattle and pigs: enhancement of lactogenic immunity

Passive immunity against enteric viral infections is dependent upon the continual presence in the gut lumen of a protective level of specific antibodies. This article examines methods currently used to enhance the titre and duration of specific antibody in the mammary secretions of cows and pigs, with particular reference to rotavirus and coronavirus infections. In addition, some of the potential problems to be found in attempting to produce vaccines against these viral infections are outlined.

Receptor mechanisms of the neonatal intestine and their relationship to immunoglobulin absorption and disease

Immunoglobulin absorption by the calf has been the subject of considerable research. Despite these efforts little is known about the cytological events that occur at the level of the intestinal epithelial cell. These events have been studied extensively and characterized in the laboratory rodent; however, there have been few attempts to make corollaries between the two species. All neonatal animals display certain similarities in their intestinal morphology that may be correlated, with immunoglobulin absorption. Selectivity in absorption appears to be variable among neonatal animal species; however, all demonstrate some selectivity. Selectivity in absorption implies that receptors are a necessary component in the transport of immunoglobulins. Selectivity further requires binding of immunoglobulins to an endocytic vesicle membrane to ensure transport through the cell, circumvention of intracellular digestion, and release at the basolateral cell membrane. A decrease of immunoglobulin absorption may be accomplished in a variety of ways such as competition between intestinal microbes and immunoglobulins for a common receptor on the intestinal epithelial cell. An additional consideration is aberrant synthesis or recycling of the cell membrane receptor, as induced by metabolic decelerators such as cortisol. Failure to recycle immunoglobulin receptors also would decrease efficiency of absorption.

Absorption of colostral immunoglobulin G in the newborn dairy calf

Five groups of eight newborn calves were used to study absorption of colostral immunoglobulin G. One feeding of 2 liters of pooled colostrum was given at one of 6, 12, 24, 36, or 48 h after birth. Concentrations of immunoglobulin G in blood plasma and feces were measured by an immunodiffusion technique. Plasma volume and fecal excretion also were measured. When colostrum was given 6 h after birth, 65.8% of the ingested immunoglobulin G appeared in the plasma. This percentage declined rapidly to reach 46.9%, 11.5%, 6.7%, and 6.0% when colostrum was given at the ages of 12, 24, 36, and 48 h. Total fecal immunoglobulin G increased linearly with age. The quantities not recovered from plasma and feces reached a maximum when colostrum was given at 24 or 36 h after birth. Immunoglobulin G can be "lost" to a great extent via routes other than plasma and feces during this time. Quantities of immunoglobulin G measured in plasma represent apparent rather than true absorption.

The post-natal development of lymph nodes in mice

A total of ten major lymph node stations have been studied in ICR-strain mice at various time intervals between birth and the age of four weeks. Comparison of lymph node volumes and of volume changes during the observation period revealed that the mesenteric lymph node (MLN) complex was larger at birth and grew at a faster rate than all other nodes. A distinct numerical increase of cortical lymphocytes in MLN at the end of the first week of life was interpreted to be the result of both immigration of T cells and moderate local proliferation, while the quantitatively more important second phase of growth at the age of between two and three weeks might be the consequence of local lymphocyte production. The comparatively modest changes in lymph nodes removed from the gut (axillary and popliteal nodes) could be explained as being due in large measure to immigration of lymphocytes originating in gut-associated lymphoid tissues (GALT).

Distributional uptake of gamma-globulin in small intestine of neonatal calves

Newborn calves deprived of colostrum were used to determine distribution of uptake of gamma-globulin labeled with iodine-125 in small intestine. Ten calves less than 12.5 h of age (average 7 h) were anesthetized, and intestines were exteriorized through an abdominal incision. Intestine was ligated into 10-cm segments, 70 cm apart, beginning at the ileocecal junction and progressing anteriorally, then each segment injected with 100 mg (appoximately 1 microCi) labeled gamma-globulin in 5 ml electrolyte solution, and incubated for 1.5 h. One additional segment was formed adjacent to segments 1, 5, and 10 to assess uptake after .5 h incubation with [iodine-125] gamma-globulin. After prescribed gamma-globulin exposure, segments were excised; then volume of lumen contents, segment weight, and tissue activity were measured. The location of each segment was the percentage of distance from cecum to abomasum. Uptake was milligrams gamma-globulin per gram of segment tissue. Distribution of gamma-globulin uptake after 1.5 h incubation was a cubic function of segment position. Uptake was greatest in a region 15% of the cecum-abomasum distance and declined progressively toward the abomasum. After .5-h incubation with gamma-globulin, regression of uptake on segment position was a quadratic function with greatest uptake at 30% of cecum-abomasum distance. Uptake was greater in segments exposed to gamma-globulin for 1.5 h than .5 h.

Endocytosis and immunoglobulin transport across the small intestine of the new-born pig

1. Measurements of porcine and human IgG transport across the small intestine of the new-born pig have been made in vivo and related to the amount of endocytosis taking place.2. The amount of immunoglobulins transported, following intraduodenal administration to conscious animals, is directly related to the degree of endocytosis which these proteins produce. Administration of protein in amounts sufficient to cause a maximal endocytotic response causes saturation of the protein transporting process.3. Absorption of small amounts of human IgG from the small intestine can be accelerated by the addition of sow colostrum or porcine IgG in quantities sufficient to stimulate endocytosis. These effects disappear when the amount of human IgG administered is itself sufficient to fully stimulate endocytosis.4. Preferential transport of porcine over human IgG can be demonstrated when both are given as a single solution to individual pigs. The degree of preference is, however, small in relation to the total amount of immunoglobulin transported.5. The initial formation of endocytotic vacuoles in the pig intestine seems, unlike the situation in rats and mice, to provide a major route for the trans-cellular movement of macromolecules including immunoglobulins. Present evidence suggests that, though sow colostrum can on occasion stimulate such transport, it does so merely by acting as a protein-containing solution to increase the amount of endocytosis taking place.

The immune response in hepatic cirrhosis: animal and human studies

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Studies on diarrhea in neonatal calves: the plasma proteins of normal and diarrheic calves during the first ten days of age

The concentration of serum proteins and plasma fibrinogen were determined in 151 normal and 49 diarrheic calves at intervals from birth to ten days of age. There were significant differences in the concentrations of the various serum proteins in normal calves when the results were analysed at six age intervals. There was no significant relationship between the concentration of the various proteins and the season of the year. Of the diarrheic calves, those that died had significantly lower gamma globulin concentrations than the other calves. Severely diarrheic and dehydrated calves had significantly increased serum albumin and alpha glabulin concentrations and decreased gamma globulin concentrations. No significant variation occurred in total serum protein concentration. Plasma fibrinogen concentrations were similar in normal and diarrheic calves.

Ionic dependence of protein transport across the new-born pig intestine

1. The everted small intestine of the new-born pig transports albumin to its serosal surface at rates which depend on the ionic composition of the bathing medium.2. Albumin transport takes place most rapidly at sodium and potassium concentrations of 120 and 6 mM respectively. Increasing the concentration of sodium or potassium, or decreasing the concentration of sodium, reduces the net transfer of albumin.3. Albumin can increase the serosal transfer of sodium, potassium and water. The calculated ionic composition of fluid transported in the presence of albumin closely resembles that presented to the mucosal surface over a wide range of sodium and potassium concentrations.4. Lowering the concentration of sodium reduces water transfer but only if albumin is present in the mucosal medium. Albumin-stimulated water transfer is only seen when the external concentration of sodium is high.5. Raising the concentration of potassium reduces water transport, whether or not albumin is present, but this reduction is too small to account for the inhibitory effect of potassium on albumin transport.6. The mutual interaction that exists between the transport of albumin and sodium is probably responsible for the increased potassium transport seen at low external concentrations of potassium. Higher concentrations of potassium appear directly to inhibit the interaction between the transport of sodium and albumin.

Structural changes in the small intestine associated with the uptake of polyvinyl pyrrolidone by the young ferret, rabbit, guinea-pig, cat and chicken

1. The entry of [(125)I]polyvinyl pyrrolidone (PVP) of mean mol. wt. 160,000 (K. 60) into the epithelial cells of the small intestine has been measured in new-born animals of five species.2. The distribution along the intestine of cells capable of taking up [(125)I]PVP and the decrease and eventual cessation of uptake (closure) with increasing age have been investigated, and have been related to changes in the histological appearance of the small intestine.3. The small intestine of the ferret took up PVP readily until 33-34 days after birth. From 34 to 37 days of age PVP uptake declined sharply and disappeared completely by 40-45 days.4. In the ferret, unlike other species studied, some PVP was taken up by the duodenum. This continued for the first 4 weeks after birth. Thereafter PVP uptake gradually became confined to the terminal ileum.5. In the guinea-pig, PVP uptake was limited to the first 48 hr after birth. During this period the site of uptake was progressively restricted to the terminal ileum.6. In the rabbit, PVP could be taken up in the distal two-thirds of the small intestine for at least 20 days after birth. A decline in uptake occurred between 20 and 22 days after birth in most animals.7. Wide individual variations were seen in the kitten, but PVP uptake was seen in some animals up to 14 days after birth.8. Newly hatched chicks and chicks tested 48 hr after hatching did not take up PVP.9. Histological examination of the small intestine with the light microscope demonstrated that in all species PVP uptake was associated with the presence of vacuoles in the epithelial cells of the villus.10. In the young guinea-pig, large PAS-positive granules were seen in the macrophages of the lamina propria. These appeared to migrate through the epithelium into the intestinal lumen. The significance of this finding and its relation to macromolecular uptake remain unclear.

The break-down of 131-I-gamma-globulin in the digestive tract of the new-born pig

1. The intestinal absorption of [(131)I]porcine and bovine serum gamma-globulin after oral administration has been investigated in conscious pigs less than 20 hr old. Absorption was measured by the concentration of (131)I in venous blood during the 6 hr after feeding and also by the distribution of (131)I between homogenates of the alimentary tract and the rest of the animal at the end of the experiment.2. The concentration of (131)I in the blood was always low after feeding [(131)I]gamma-globulin, although a large proportion of the isotope fed was found to have left the alimentary tract. This indicated that much of the [(131)I]-gamma-globulin had been hydrolysed into fragments of low mol.wt. which were not retained in the plasma. There were no significant differences between results obtained with homologous and heterologous gamma-globulin.3. Examination by gel-filtration confirmed that, after feeding [(131)I]-serum gamma-globulin, much of the (131)I in the plasma was associated with material of mol.wt. less than 12,400 and demonstrated that the break-down of bovine gamma-globulin was comparable with that of homologous gamma-globulin.4. Comparison of the absorption of [(131)I]serum gamma-globulin from colostrum with that from a chloride solution with a similar Na(+) and K(+) concentration showed that, although the blood concentration remained low, colostrum reduced the hydrolysis of the labelled protein.5. This effect of colostrum could be simulated by the addition to the chloride solution of either the synthetic trypsin inhibitor Trasylol or a higher concentration of unlabelled protein.6. Gel-filtration of samples of the contents of the stomach, duodenum and terminal ileum after feeding [(131)I]serum gamma-globulin showed that proteolysis occurred at all these sites.

The influence of specific chemical factors in the solvent on the absorption of macromolecular substances from the small intestine of the new-born calf

1. The absorption, without change, of [(131)I] and [(125)I]solutes of high molecular weight after duodenal infusion has been measured in anaesthetized calves less than 20 hr old by analysis of lymph collected from the thoracic or intestinal duct.2. Factors present in boiled bovine colostrum whey known to be necessary for the rapid absorption of [(131)I]bovine serum gamma-globulin have now been shown to accelerate the passage of [(131)I]polyvinyl pyrrolidone (PVP) of mean mol. wt. 160,000 (K.60) into the lymph in a comparable manner.3. [(131)I]PVP K.30 (mean mol. wt. 40,000) and [(131)I]human serum albumin could be absorbed to some degree in the absence of solvent factors necessary for the absorption of solutes of higher mol. wt. and a large proportion of the solute thus absorbed passed directly into the portal capillaries.4. Lactate and pyruvate and salts of certain lower volatile fatty acids resemble factors in colostrum whey in their facilitation of the absorption of both gamma-globulin and PVP K.60: these active compounds were not however found in colostrum in significant quantities.5. Potassium isobutyrate was the most effective of the compounds tested and at concentrations of 56.7 m-mole/l. generally accelerated absorption to a greater degree than did colostrum whey itself.6. Absorption of both gamma-globulin and PVP K.60 from colostrum whey was characterized by a profuse flow of lymph containing relatively low concentrations of labelled solute. In contrast, when these solutes were fed in solutions containing simple compounds such as potassium isobutyrate they appeared in very high concentrations in the lymph, the flow of which remained relatively scant.7. When [(125)I]PVP was administered in water, little was absorbed. If, however, such an infusion was followed 3 hr later by a duodenal infusion of colostrum, [(125)I]PVP passed into the lymph almost immediately. This response was too rapid for the colostrum to have reached the absorbing cells in the terminal ileum.8. Intravenous infusions of L+lactate have been found to facilitate the absorption of [(125)I]PVP K.60 introduced into the duodenum in water. This indicates that some of the solvent factors which accelerate absorption may reach the terminal ileum via the blood vascular system after they themselves have been absorbed from the upper small intestine.

Interdependence of albumin and sodium transport in the foetal and new-born pig intestine

1. Everted sacs of new-born pig intestines incubated in bicarbonate saline at 37 degrees C, transferred bovine plasma albumin across the mucosa into fluid bathing the serosa, the amount transferred increasing as the concentration of albumin in the mucosal fluid was raised from 0.5 to 16 g/100 ml.2. The rate of albumin transfer across the foetal pig intestine showed an apparent maximum, about 400 mug/g intestine/hr, 2 weeks before birth. The transfer at birth, about 200 mug/g intestine/hr, fell sharply during the next 2 days but later returned to that previously found at birth.3. When sacs were prepared from the intestines of 1 to 7-day-old pigs part of the recovered albumin was degraded. No digestion was found when the intestines of new-born or foetal pigs were used.4. The transfer of water and sodium, but not glucose, measured across the foetal and new-born pig intestine, was consistently higher when albumin was present in the mucosal fluid: the transmural potential difference was lowered by the presence of albumin. These differences disappeared during the first 2 days of life.5. Both the total and ouabain-sensitive adenosine triphosphatase (ATPase) activities of the pig intestinal epithelium fell within 24 hr of birth. There was some increase in total ATPase activity in older pigs but the ouabain-sensitive activity remained low.6. The relation between albumin and sodium transport, seen at a time when albumin is not being metabolized, suggests that the transfers are closely coupled. The movement of sodium into a mucosal cell down its own concentration gradient may provide energy for the translocation of albumin.

Uptake of protein by mammalian cells: an underdeveloped area. The penetration of foreign proteins into mammalian cells can be measured and their functions explored

Although it is accepted on the basis of biological and morphological evidence that mammalian cells will take up macromolecules, little is known about the kinetics, the specificity, and the functions of this uptake. With labeled proteins used as models, it is found that the transport proceeds at very low rates, requires little energy, and is markedly enhanced by polybasic compounds. Molecular charge and size are important factors: cells clearly favor cationic macromolecules of large molecular weights. Neither factor, however, can fully account for the selectivity detected in the uptake of different proteins. Ingested albumin undergoes rapid and extensive degradation. This fact suggests that macromolecules have only a limited chance to express their biological activity in target cells, a finding that is relevant also to the role of foreign nucleic acids and the possibility of achieving genetic transformation in animal cells. There are concrete indications, however, that in spite of their short half-life, proteins can act as carriers, as precursors of active agents, and as regulators of metabolic functions in host cells. They may also be important in the control of growth and differentiation. These functions of exogenous proteins are still largely unexplored.

The in vitro transfer of bovine immune lactoglobulin across the intestine of new-born pigs

1. Everted sacs of pig intestine, used soon after birth, maintained transmural potentials and transferred water and glucose to the serosal surface.2. Immune globulin, fed as bovine colostrum to the new-born pig, appeared in the serosal fluid of everted sacs during incubation in bicarbonate saline. The particular segment showing maximum transferring ability varied between limits and appeared to depend on the amount or concentration of colostrum fed to the pig. Sacs from unfed pigs incubated in bovine colostrum also transferred colostral IgG to the serosal fluid. This transfer was dependent on the concentration of colostral IgG in the incubation medium and became more pronounced in the middle third of the small intestine.3. Human serum albumin inhibited the transfer of colostral IgG and about twenty molecules of albumin were transferred for every molecule of colostral IgG, when both were presented together in equal concentration on the basis of weight, to the middle segment of the small intestine.4. Some of the immune globulin collected in vitro after feeding bovine colostrum was found in a degraded form, but the amounts present could not be estimated. There was no apparent degradation of immune globulin in the purely in vitro experiments.5. The in vitro transfer of bovine colostral IgG showed selectivity between molecules of albumin and colostral IgG, the nature of which warrants further study.