Biomedical subjects

P F Pollack

Publications and source records attributed to P F Pollack.

12 recordsLinked to original sources

PubMed1996

Cysteine supplementation increases glutathione, but not polyamine, concentrations of the small intestine and colon of parenterally fed newborn rabbits.

The glutathione precursor cysteine is not contained in most total parenteral nutrition (TPN) formulations, and premature infants may not be capable of synthesizing cysteine because of a deficiency of cystathionase. Glutathione depletion may have negative effects on host defense against oxidative damage. Several studies have suggested that glutathione depletion induces ornithine decarboxylase activity and increases in polyamine concentrations. Since an inverse relationship between polyamine and glutathione concentrations has been suggested, the concentrations of both of these compounds may be altered in premature infants receiving TPN. We measured glutathione and polyamine concentrations of the small intestine and colon of prematurely delivered newborn rabbits administered TPN for 7 days after birth with or without added cysteine (75 or 150 mg kg-1 day-1). Maternally reared kits were also studied. Total glutathione concentrations in the gastrointestinal tract were significantly lower in kits administered cysteine-free TPN than in kits receiving cysteine or who were maternally reared. Polyamine concentrations did not differ among groups. Glutathione depletion of the small intestine and colon does occur during cysteine-free parenteral nutrition and may compromise intestinal defense against oxidant damage.

Animals↗

PubMed1992

Polyamines in human and rat milk and in infant formulas.

Polyamines are ubiquitous compounds known to be involved in cell proliferation and differentiation in many tissues. Enteral administration of these compounds has been shown to produce effects in suckling and adult animals. Using HPLC techniques, we verified the presence of putrescine, spermidine, and spermine in human milk and quantitated their concentration in samples collected from the first week up to 4 mo of lactation. Mean values of these compounds ranged (per liter) from 0 to 615 nmol putrescine, from 73 to 3512 nmol spermidine, and from 722 to 4458 nmol spermine. Polyamine concentrations in infant formulas were dependent on the protein source, the particular polyamine, and the protein concentration of the formula. Concentrations of these three compounds in rat milk over the first 3 wk of lactation were higher than in human milk, with spermidine being the polyamine most elevated compared with human milk (almost 20-fold higher). An artificial formula used for the rearing of suckling rats contained trace to immeasurable amounts of polyamines. Our study identifies milk as one vehicle for polyamine delivery to the intestinal mucosa of suckling animals.

Animals↗

PubMed1990

Effect of secretin on growth of stomach, small intestine, and pancreas of developing rats.

Secretin is present in the intestine of a number of developing species, and plasma secretin levels are elevated in newborn pigs and humans. Secretin stimulates the growth and affects the enzymatic composition of the stomach, small intestine, and pancreas in adult rats. This suggests a possible role for secretin in the rapid postnatal growth of these organs. We investigated this hypothesis by injecting rats subcutaneously with secretin (100 micrograms/kg) every 12 hr for seven days beginning on postnatal day 3, 6, 13, or 24. Growth parameters (weight, content of protein, DNA) as well as the composition of organ-specific enzymes of the stomach, small intestine, and pancreas were measured. Secretin increased growth parameters of the stomach and small intestine in a similar pattern, and in a quantitatively different fashion from that observed in the pancreas. Secretin's effects were also dependent on postnatal age for all organs studied. These data demonstrate that secretin can influence organ growth and enzyme composition of the stomach, small intestine, and pancreas of developing rats and may be one factor regulating growth and development of these organs.

Aging↗

PubMed1989

Effects of enterally- and parenterally-administered bombesin on intestinal luminal tryptic activity and protein in the suckling rat.

Because of the presence of bombesin-like immunoreactivity in milk, we investigated if enteral administration of bombesin affects the intestinal luminal content of trypsin and protein in 12-14-day-old rats. Bombesin (40 micrograms/kg), given either orogastrically or subcutaneously, produced a significant elevation in the intestinal content of trypsin activity. Thus, enterally-administered bombesin can produce acute biologic effects in suckling rats.

Administration, Oral↗

PubMed1989

Age and enzyme specificity of the response of developing rat pancreas to the trophic effects of bombesin.

The immediate postnatal period is a time of rapid pancreatic growth and development. Gastrointestinal regulatory peptides have been shown to exert trophic effects on the pancreas, and one such peptide, bombesin, has been shown to exert trophic effects on the pancreas of both the suckling and adult rat. Our previous studies had suggested that the sensitivity of the rat pancreas to bombesin might be changing during the suckling period. We therefore conducted experiments to determine if age-related changes in the responsiveness of rat pancreas to chronic administration of exogenous bombesin occur, and to characterize these changes. Beginning on day 3 ("suckling") or 24 ("weanling") postnatally, groups of rats were injected subcutaneously with several doses of bombesin tetradecapeptide every 12 h for 7 days. Bombesin injection produced a dose-dependent increase in pancreatic protein content and trypsin activity in both suckling and weanling groups, although the degree of increase was greater in the weanling group than in the sucklings. Significant increases in pancreatic contents of DNA and amylase activity were observed only in the weanling group. We have thus demonstrated for the first time that the pancreas of the suckling rat exhibits a diminished response to chronic parenteral administration of bombesin in terms of changes in protein and DNA contents, as well as enzyme composition, compared to the pancreas of weanlings. The elucidation of the physiologic basis for these differences may provide specific information regarding the mechanism of bombesin-stimulated pancreatic growth, as well as general information concerning the control of pancreatic growth during development.

Aging↗

PubMed1987

Growth of premature infants fed formulas with 10%, 30%, or 50% medium-chain triglycerides.

Questions regarding fat deposition and hormonal control of lipogenesis in infants fed formulas containing medium-chain triglycerides have been raised by studies in animals. To compare growth, clinical observations, and laboratory measures of infants fed the same basic isocaloric formulas with 10%, 30%, or 50% of the total fat as medium-chain triglycerides, we studied longitudinally for the first four weeks of life 22 infants who weighed 1000 to 1750 g. We found no differences in weight or skin-fold thickness between the groups. There were no clinical characteristics to distinguish one group from another. Two-hour postprandial levels of insulin and glucagon showed no differences one week to ten days after the start of the formula diet. The skin-fold thickness of all infants studied continued to increase after birth, regardless of weight loss. The increase in skin-fold thickness was comparable with the increase expected in the fetus in utero, but not significantly greater. The weight curve was parallel to the fetal weight curve but was lower, due to the first-week loss that possibly reflected a loss of body water, as suggested by the dynamic skin-fold thickness curve.

Humans↗

PubMed1987

Effects of enterally fed epidermal growth factor on the small and large intestine of the suckling rat.

Epidermal growth factor (EGF) has been shown to be present in the milk of several species, including the rat, and to have gastrointestinal effects when given parenterally or orally in pharmacologic doses. We investigated the effect of enteral EGF in physiologic doses on the small intestine and colon of suckling rats. Serum thyroxine (T4) levels were also measured. Rats were gavage-fed by hand with an artificial formula with or without added EGF every 3 h from 11 to 14 days of age. Intake was adjusted to deliver 30 kcal/100 g b.wt./day of formula and 16 micrograms/kg/day of EGF approximating the daily caloric intake, and about twice the estimated daily EGF intake for suckling rats. Weight gain did not differ between groups (fed EGF: 3.8 + 0.2 g; not fed EGF: 3.7 + 0.1 g). The protein content of the whole colon of rats fed an EGF-containing formula was significantly lower and the DNA content significantly higher, than in rats fed formula without added EGF. The protein/DNA ratio was therefore markedly higher in the animals fed formula without added EGF; these effects were most evident in the distal colon. In contrast, there was no effect of EGF on small intestinal protein and DNA content; lactase, sucrase, and maltase activities were likewise unaffected, as was serum T4. These data suggest a physiologic role for breast milk EGF in the development of the suckling rat colon.

Animals↗

PubMed1986

Isolated pancreatic acini from suckling and weanling rats: changes in amino acid incorporation and carbachol-stimulated amylase secretion with age.

To characterize the changes in pancreatic function during postnatal development, isolated pancreatic acini were prepared from rats aged 8-9, 12-14 and 20 days and from adult rats. Isolated acini maintained a normal microscopic appearance and viability as judged by exclusion of trypan blue and linear incorporation of tritiated leucine into total protein. The rate of incorporation in 8-day-old acini was 20% of that observed in adult rats. Significant dose-dependent increases in amylase release in response to carbachol were observed in all age groups; stimulated amylase secretion was significantly less in the 8- to 9- and 12- to 14-day-old animals than in the 20-day-old and adult rats. These data indicate that viable isolated pancreatic acini can be prepared from suckling rats and that these acini exhibit an altered in vitro responsiveness to carbachol. This preparation should therefore be a useful model for in vitro studies of the development of pancreatic function.

Amino Acids↗

PubMed1976

Necrotizing enterocolitis in term infants.

Despite the fact that necrotizing enterocolitis is considered a disease of premature infants, 20% of all affected infants at Babies Hospital over the past 20 years were products of term gestations. Two distinct subgroups of such infants were noted (1) five infants with congenital heart disease and/or congestive heart failure (e.g.hypoplastic left heart syndrome), all but one of whom developed the disease in the first week of life; (2) eight infants who developed the disease at a much later age after a protracted period of diarrhea. This histopathologic features of the disease in term infants are the same as those in premature infants. Further, the pathogenesis of the disease in term infants does not appear to differ basically from that in premature infants. These facts, lead away from the concept of NEC as a disease of simple etiology.

Diarrhea, Infantile↗

PubMedDate not supplied

Processing and transfer of epidermal growth factor in developing rat jejunum and ileum.

Using everted sac technique we demonstrated the transfer of 125I-mEGF across the jejunal and ileal walls of suckling, weanling and adult rats. The transfer by the suckling rat jejunum and ileum was significantly inhibited by the presence of dinitrophenol and sodium azide or by the replacement of sodium with potassium or choline, RP-HPLC analysis detected carboxy-terminal processing of 125I-mEGF in suckling and adult rat jejunum and ileum. Suckling rat jejunum produced 125I-des(53)mEGF and 125I-des(49-53)mEGF, whereas 125I-des(48-53)mEGF was detected in suckling rat ileum or adult rat jejunum and ileum. All three forms of 125I-mEGF bound to anti-EGF antibody and EGF receptors. The receptor binding of 125I-des(53)mEGF was higher than that of 125I-mEGF, but those of 125I-des(49-53)mEGF and 125I-des(48-53)mEGF were greatly diminished. Results indicate a carboxy-terminal processing of mouse EGF during uptake and transfer in the small intestine of developing and adult rats, and the resulting products showed altered receptor binding. An identical amino acid sequence of the C-terminal pentapeptide of eGF from mouse, human and possibly rat may suggest a biological significance of C-terminal processing of EGF in the small intestine.

Animals↗

PubMedDate not supplied

100 patient years' experience with the Broviac silastic catheter for central venous nutrition.

Use of the Broviac silastic catheter totaling 37,039 patient days' experience has been studied at UCLA Hospital. When combined with standardized protocol for performance of parenteral nutrition and line care, and consistently supervised, the Broviac catheter provided inpatient as well as home parenteral nutrition with minimal complications. Catheter-related sepsis occurred once every 1,058 catheter-use days; minor or major complications developed once every 330 days. The benefits of the Broviac catheter appear to stem from the reinforcement of the external portion of the catheter with an outer protective sheath of Teflon, the luer lock connecting apparatus at the end of the catheter, and the dacron cuff which served to anchor the catheter by stimulating adhesion formulation. The ability to repair the catheter by splicing avoided removal of 7% of all catheters. Particularly dramatic results were noted in infants younger than 2 yr; sepsis and dislodgement occurred only once every 1189 catheter-use days. On the basis of these observations, the Broviac silastic catheter should currently be considered the catheter of choice for central venous alimentation.

Adolescent↗

PubMedDate not supplied

Three-in-one parenteral nutrition: a safe and economical method of nutritional support for infants.

The medical records of 20 infants under 1 year of age who received parenteral nutrition (PN) for a minimum of 1 week were reviewed. Patients were divided into two groups based on the method of PN administration. One group received PN by the traditional two-plus-one method where lipid emulsion is given separately from the dextrose-amino acid mixture. The second group received PN by the three-in-one method where lipid emulsion is admixed with the dextrose and amino acids. There were no statistically significant differences between the two groups in the amount of calories, lipid, dextrose, protein, calcium, and phosphorus received per kg of body weight. Average daily weight gain was not statistically different, and no obvious trends were noted in serum biochemical parameters between the two groups. Average total PN days for the groups (13 +/- 7 days for the two-plus-one group vs 39 +/- 35 days for the three-in-one group) were significantly different (p less than 0.05). A cost comparison of the two methods of PN administration indicated that the two-plus-one method costs our hospital $11.78 more per day than the three-in-one solution. We conclude that the three-in-one method of PN administration is safe, efficacious, and cost effective for infants under 1 year of age.

Cost-Benefit Analysis↗