摘要:

We used anin vitroassay to study and compare the growth-promotional activity of protein and nonprotein components in human milk (HM) and cow milk (CM) samples for infant strains of Bifidobacterium species. HM samples varied considerably in growth-promotion activity forBifidobacterium bifidumvarpennsylvanicus, Bifidobacterium infantis, andBifidobacterium breve.Pooled CM samples showed similar but less variable levels of activity when compared with HM samples. Separation of milk samples by ultrafiltration into protein nitrogen and nonprotein nitrogen (NPN) fractions revealed that the bifidobacteria growth-promotion activity of HM was associated primarily with the NPN fraction, whereas activity in CM whey was found in both protein nitrogen and NPN fractions. Testing of purified CM whey proteins showed that α-lactalbumin and lactoferrin were potent growth promoters, showing greater activity forB. infantisandB. brevethan for two strains ofB. bifidum.Conversely, N-acetylglucosamine and purified gastric mucin were highly active forB. bifidumstrains but inactive for other Bifidobacterium species. Collectively, the data indicate that both protein nitrogen and NPN factors in HM and CM promote the growth of bifidobacteria and suggest that Bifidobacterium species differ in responsiveness to protein and oligosaccharide growth promoters.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Amniotic fluid volume is regulated by a balance of fetal fluid production and resorption. Although fetal swallowing is believed to be a major site of fluid resorption, additional routes of fluid exchange also may contribute. In our present study, five chronically prepared, water-restricted, pregnant ewes with singleton fetuses (128 ± 1 d) were rehydrated via an intraamniotic infusion (100 mL/h over 90 min) of 0.075 M saline. In response to the maternal water restriction, significant increases were noted in maternal and fetal plasma osmolalities (306.6 ± 1.2 to 315.4 ± 2.4; 300.5 ± 1.5 to 311.0 ± 1.6 mosmol/kg, respectively) and arginine vasopressin concentrations (1.9 ± 0.2 to 22.6 ± 5.0; 1.5 ± 0.1 to 8.5 + 2.2 pg/mL, respectively). After the intraamniotic infusion, fetal plasma osmolality (311.0 ± 1.6 to 303.0 ± 1.2 mosmol/kg) and hematocrit (36.7 ± 1.9 to 33.8 ± 1.4%) significantly decreased although there was no change in maternal arterial blood values. Fetal swallowing averaged 0.39 ± 0.10 mL/min during the basal period and 0.34 ± 0.17 mL/min at maximum dehydration, and decreased significantly to 0.19 ± 0.07 mL/min in response to the intraamniotic infusion. These results indicate the rapid absorption of intraamniotic fluid by the dehydrated ovine fetus, despite the suppression of fetal swallowing. The volume swallowed during and after the intraamniotic infusion was insufficient to account for the observed changes in fetal plasma osmolality and hematocrit. Thus, alternative routes of fluid absorption (i.e. intramembranous flow) likely predominate under conditions of increased fetal plasma to amniotic fluid osmotic gradients.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID