scholarly journals Lactase phlorhizin hydrolase turnover in vivo in water-fed and colostrum-fed newborn pigs

1996 ◽  
Vol 320 (3) ◽  
pp. 735-743 ◽  
Author(s):  
Mary A. DUDLEY ◽  
Douglas G. BURRIN ◽  
Andrea QUARONI ◽  
Judy ROSENBERGER ◽  
Gary COOK ◽  
...  
Keyword(s):  
Post Partum ◽  
Specific Radioactivity ◽  
Experimental Treatment ◽  
Synthesis Rate ◽  
Jejunal Mucosa ◽  
Treatment Groups ◽  
Newborn Pigs ◽  
The Absolute ◽  
Absolute Synthesis

We have estimated the synthesis rates in vivo of precursor and brush-border (BB) polypeptides of lactase phlorhizin hydrolase (LPH) in newborn pigs fed with water or colostrum for 24 h post partum. At the end of the feeding period, piglets were anaesthetized and infused intravenously for 3 h with l-[4-3H]-phenylalanine. Blood and jejunal samples were collected at timed intervals. The precursor and BB forms of LPH were isolated from jejunal mucosa by immunoprecipitation followed by SDS/PAGE, and their specific radioactivity in Phe determined. The kinetics of precursor and BB LPH labelling were analysed by using a linear compartmental model. Immunoisolated LPH protein consisted of five polypeptides [high-mannose LPH precursor (proLPHh), complex glycosylated LPH precursor (proLPHc), intermediate complex glycosylated LPH precursor (proLPHi) and two forms of BB LPH]. The fractional synthesis rate (Ks) of proLPHh and proLPHc (approx. 5%/min) were the same in the two groups but the absolute synthesis rate (in arbitrary units, min-1) of proLPHh in the colostrum-fed animals was twice that of the water-fed animals. The Ks values of proLPHi polypeptides were significantly different (water-fed, 3.89%/min; colostrum-fed, 1.6%/min), but the absolute synthesis rates did not differ. The Ks of BB LPH was not different between experimental treatment groups (on average 0.037%/min). However, the proportion of newly synthesized proLPHh processed to BB LPH was 48% lower in colostrum-fed than in water-fed animals. We conclude that in neonatal pigs, the ingestion of colostrum stimulates the synthesis of proLPHh but, at least temporarily, disrupts the processing of proLPH polypeptides to the BB enzyme.

scholarly journals Oestradiol inhibits collagen breakdown in the involuting rat uterus

1972 ◽  
Vol 127 (4) ◽  
pp. 705-713 ◽  
Author(s):  
Janet N. Ryan ◽  
J. Frederick Woessner
Keyword(s):  
Cathepsin D ◽  
Density Gradient Centrifugation ◽  
Post Partum ◽  
Gradient Centrifugation ◽  
Specific Radioactivity ◽  
Rat Uterus ◽  
Oestradiol Treatment ◽  
Cathepsin D Activity ◽  
Stimulation Of

1. The earlier observation (Woessner, 1969) of oestradiol inhibition of collagen breakdown is confirmed and extended. Administration of 100μg of oestradiol-17β/day to parturient rats strongly inhibits the loss of collagen from the involuting uterus. Three experiments show that this effect is due to an inhibition of collagen degradation rather than to a stimulation of collagen synthesis. 2. Uterine collagen was labelled with hydroxy[14C]-proline by the administration of [14C]proline near the end of pregnancy. By 3 days post partum, control uteri lost 83% of their collagen and 90% of their hydroxy[14C]proline. Uteri from oestradiol-treated rats lost only 50% of both total and labelled hydroxyproline, with no decrease in the specific radioactivity of the hydroxyproline. 3. Incorporation of [14C]proline into uterine collagen hydroxyproline in vivo was not affected by oestradiol treatment. 4. Urinary excretion of hydroxyproline was increased in post-partum control rats and decreased in oestradiol-treated rats. 5. An enzyme capable of cleaving 4-phenylazobenzyloxycarbonyl-l-prolyl-l-leucylglycyl- l-prolyl-d-arginine (a substrate for clostridial collagenase) increased in activity in the post-partum uterus and was unaffected by oestradiol treatment. 6. Uterine homogenates digested uterine collagen extensively at pH3.2. This digestion was unaffected by the oestradiol treatment. 7. Lysosomal fractions prepared by density-gradient centrifugation of uterine homogenates contained coincident peaks of cathepsin D activity and peptide-bound hydroxyproline. The cathepsin D and hydroxyproline contents of this peak were unaffected by oestradiol treatment.

scholarly journals [3H]proline incorporation and hydroxyproline concentration in articular cartilage during the development of osteoarthritis caused by immobilization. A study in vivo with rabbits

1981 ◽  
Vol 200 (2) ◽  
pp. 435-440 ◽  
Author(s):  
T Videman ◽  
I Eronen ◽  
T Candolin
Keyword(s):  
Total Protein ◽  
Collagen Synthesis ◽  
Weight Bearing ◽  
Specific Radioactivity ◽  
Collagen Content ◽  
Synthetic Activity ◽  
Synthesis Rate ◽  
Hydroxyproline Concentration ◽  
Proline Incorporation

Proline metabolism in vivo was studied during the development of immobilization osteoarthritis in rabbits. Collagen content was measured as the hydroxyproline concentration of the tissue in question. The incorporation of [3H]proline was used as the indicator for total protein synthesis; collagen synthesis rate was estimated from measurements of the specific radioactivity of hydroxyproline. Cartilage samples from knee and hip joints were analysed after 3, 7, 11, 18, 35 and 56 days of immobilization. The total protein and collagen synthesis rates of the immobilized legs increased and reached a maximum after 11-35 days. Although they decreased thereafter, these rates remained elevated to the end of the experiment. A slight increase in the synthetic activity of the non-immobilized contralateral legs was also detected after 7--18 days of immobilization. The isotope incorporation was markedly higher in tibial marginal tissue than in weight-bearing cartilage. In spite of the increased synthesis, no clear changes were found in the collagen content of the tissues studied during the experiment.

scholarly journals Protein synthesis in rat lung. Measurements in vivo based on leucyl-tRNA and rapidly turning-over procollagen I

1984 ◽  
Vol 222 (1) ◽  
pp. 77-83 ◽  
Author(s):  
J Kelley ◽  
W S Stirewalt ◽  
L Chrin
Keyword(s):  
Plasma Proteins ◽  
Specific Radioactivity ◽  
Young Male ◽  
Male Rats ◽  
Synthesis Rate ◽  
Vascular Perfusion ◽  
Fractional Synthesis ◽  
Free Serum ◽  
Procollagen Iii

The relationships of the specific radioactivities of leucine in serum, leucine acylated to tRNA and leucine in procollagen I, procollagen III and total protein in lungs of unanaesthetized young male rats in vivo were assessed as a function of time during constant intravenous infusion of radiolabelled leucine. The specific radioactivity of free leucine in plasma reached a steady-state plateau value within 30 min of initiation of [3H]leucine infusion. Leucine acylated to tRNA isolated from lungs had the same specific radioactivity as free serum leucine. Leucine in procollagen I rapidly achieved a specific radioactivity equal to that of serum leucine and leucyl-tRNA, indicating that serum leucine and leucyl-tRNA isolated from total lung were in rapid equilibrium with the precursor leucine pool for procollagen I synthesis. On the basis of leucyl-tRNA or free serum leucine as the precursor, half-times of fractional conversion of procollagen I and III were calculated as 9 and 38 min respectively. The incorporation of leucine into mixed lung proteins calculated from the tracer studies was 6.8 mumol/day for the first 30 min of the infusion, after which the calculated rate increased to 15.0 mumol/day. This apparent increase correlated with the appearance of rapidly labelled plasma proteins trapped in the lungs. On the basis of short infusions lasting 30 min or less, followed by vascular perfusion of the lung, the average fractional synthesis rate of mixed pulmonary proteins in young male rats was 20%/day.

Diet-induced changes in gene expression of lactase in rat jejunum

1995 ◽  
Vol 268 (6) ◽  
pp. G1066-G1073 ◽  
Author(s):  
T. Goda ◽  
H. Yasutake ◽  
Y. Suzuki ◽  
S. Takase ◽  
O. Koldovsky
Keyword(s):  
Gene Expression ◽  
Corn Oil ◽  
Unit Weight ◽  
Synthesis Rate ◽  
Mrna Levels ◽  
Lactase Activity ◽  
High Starch ◽  
The Absolute ◽  
Absolute Synthesis ◽  
Starch Diet

To explore the mechanisms by which jejunal lactase activity is modified by carbohydrate and/or fat intake, mRNA levels and the absolute synthesis rate of lactase-phlorizin hydrolase (LPH) were determined in 6-wk-old rats that were fed either low-starch diets containing long-chain triacylglycerol (LCT, 73% energy as corn oil) or medium-chain triacylglycerol (MCT, 66% energy as MCT, 7% energy as corn oil), or a high-starch diet (70% energy as cornstarch) for 7 days. LPH mRNA levels in the jejunum were similar between LCT-fed and MCT-fed rats, but animals fed the high-starch diet exhibited a greater (2x) LPH mRNA level than other groups. The absolute synthesis rate of LPH, estimated by the flooding dose technique using [3H]phenylalanine, was greater (2.4x) in rats fed the high-starch diet than in other groups. A short-term force-feeding experiment revealed that sucrose was able to evoke LPH mRNA levels within 12 h but that a nonmetabolizable sugar (alpha-methylglucoside) was unable to enhance it. By contrast, animals fed the high-LCT diet showed a lower (by 30%) lactase activity than rats fed the low-starch, high-MCT diet, which was accompanied by not only a reduction of immunoreactive LPH in brush-border membranes but also a reduction in lactase activity per unit weight of immunoreactive LPH. These results suggest that both gene expression and posttranslational events of LPH might be influenced by dietary manipulations; carbohydrate intake primarily increases LPH mRNA levels, and LCT accelerates inactivation and/or degradation of lactase.

scholarly journals Glucose metabolism in the newborn rat. Temporal studies in vivo

1973 ◽  
Vol 132 (4) ◽  
pp. 739-752 ◽  
Author(s):  
Keith Snell ◽  
Deryck G. Walker
Keyword(s):  
Intraperitoneal Injection ◽  
Glucose Utilization ◽  
Ketone Bodies ◽  
Post Partum ◽  
Specific Radioactivity ◽  
Liver Glycogen ◽  
Uterine Environment ◽  
Lactate Formation ◽  
Lactate Utilization

1. The concentrations of plasma d-glucose, l-lactate, free fatty acids and ketone bodies and of liver glycogen were measured in caesarian-delivered newborn rats at time-intervals up to 4h after delivery. Glucose and lactate concentrations decreased markedly during the first hours after delivery, but there was a delay of 60–90min before significant glycogen mobilization occurred. 2. The specific radioactivity of plasma d-glucose was measured as a function of time for up to 75min after the intraperitoneal injection of d-[6-14C]glucose and d-[6-3H]glucose into caesarian-delivered rats at 0, 1 and 2h after delivery. Calculations revealed that there was an appreciable rate of glucose formation at all ages studied, but immediately after delivery this was exceeded by the rate of glucose utilization. Around 2h post partum the rate of glucose utilization decreased dramatically and this coincided with a reversal of the immediately postnatal hypoglycaemia. 3. The specific radioactivity of plasma l-lactate and the incorporation of 14C into plasma d-glucose and liver glycogen was measured as a function of time after the intraperitoneal injection of l-[U-14C]lactate into rats immediately after delivery. The logarithm of the specific radioactivity of plasma l-[U-14C]lactate decreased linearly with time for at least 60min after injection and the calculated rate of lactate utilization exceeded the rate of lactate formation. 4. 14C incorporation into plasma d-glucose was maximal from 30–60min after injection of l-[U-14C]lactate and the amount incorporated at 60min was 23% of that present in plasma lactate. Although 14C was also incorporated into liver glycogen the amount was always less than 3% of that present in plasma glucose. 5. The results are discussed in relationship to the adaptation of the newly born rat to the extra-uterine environment and the possible involvement of gluconeogenesis at this time before feeding is established.

scholarly journals Protein degradation rates in regions of the central nervous system in vivo during development

1978 ◽  
Vol 170 (3) ◽  
pp. 637-642 ◽  
Author(s):  
D S Dunlop ◽  
W V Elden ◽  
A Lajtha
Keyword(s):  
Nervous System ◽  
Protein Degradation ◽  
Cerebral Hemisphere ◽  
Post Partum ◽  
Active Phase ◽  
High Rate ◽  
Synthesis Rate ◽  
Degradation Rates ◽  
The Central Nervous System

The rate of protein degradation was estimated in several regions of rat brain at various ages by subtracting the rate of accumulation of protein from the rate of synthesis. The rate of degradation in cerebral hemisphere, which was 1.3%/h at 2 days of age, declined steadily with age, approaching the synthesis rate is about 30 days of age (0.8%/h). Degradation rates in the pons medulla, mid-brain and spinal cord were of a similar order to that in the cerebral hemisphere. The cerebellum had an exceptionally high rate of degradation in young rats, 1.9%/h at 2 days of age, which complemented its high rates of synthesis and accumulation. The degradation rate in the young was 2-2.5 times the rate in older rats and was approx. 65% of the synthesis rate during the more active phase of growth. The rapid accumulation of protein in the nervous system during the first week post partum was accompanied by high rates of breakdown, and was the result of a relatively small difference between that high rate of degradation and an even higher synthesis rate.

Parenteral nutrition selectively decreases protein synthesis in the small intestine

1998 ◽  
Vol 274 (1) ◽  
pp. G131-G137 ◽  
Author(s):  
Mary A. Dudley ◽  
Linda J. Wykes ◽  
Alden W. Dudley ◽  
Douglas G. Burrin ◽  
Buford L. Nichols ◽  
...  
Keyword(s):  
Small Intestine ◽  
Elemental Diet ◽  
Elongation Factor ◽  
Synthesis Rate ◽  
Fractional Synthesis ◽  
Small Intestinal ◽  
The Absolute ◽  
Mucosal Protein ◽  
Nutrient Administration ◽  
Absolute Synthesis

We investigated the effects of an elemental diet fed parenterally or enterally on total mucosal protein and lactase phlorizin hydrolase (LPH) synthesis. Catheters were placed in the stomach, jugular vein, and carotid artery of 12 3-day-old pigs. Half of the animals were given an elemental regimen enterally and the other half parenterally. Six days later, animals were infused intravenously with [2H3]leucine for 6 h and killed, and the midjejunum of each animal was collected for analysis. The weight of the midjejunum was 8 ± 1.5 and 17 ± 1.6 g in parenterally fed and enterally fed piglets, respectively. LPH activities (μmol ⋅ min−1 ⋅ g protein−1) were significantly higher in parenterally vs. enterally fed piglets. Total small intestinal LPH activities were lower in parenterally vs. enterally fed animals. The abundance of LPH mRNA relative to elongation factor-1α mRNA was not different between groups. The fractional synthesis rate of total mucosal protein and LPH was significantly lower in parenterally fed animals (67 ± 7 and 66 ± 7%/day, respectively) than in enterally fed animals (96 ± 7 and 90 ± 6%/day, respectively). The absolute synthesis rate (the amount of protein synthesized per gram of mucosa) of total mucosal protein was significantly lower in parenterally fed than in enterally fed piglets. However, the absolute synthesis rate of LPH was unaffected by the route of nutrient administration. These results suggest that the small intestine partially compensates for the effects of parenteral feeding by maintaining the absolute synthesis rate of LPH at the same levels as in enterally fed animals.

scholarly journals Stimulation of epidermal protein synthesis in vivo by topical triamcinolone acetonide

1987 ◽  
Vol 247 (3) ◽  
pp. 525-530 ◽  
Author(s):  
C S Harmon ◽  
J H Park
Keyword(s):  
Protein Synthesis ◽  
Triamcinolone Acetonide ◽  
Gastrocnemius Muscle ◽  
Specific Radioactivity ◽  
Topical Administration ◽  
Hairless Mouse ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Fractional Rate

The rate of epidermal protein synthesis in vivo was determined in the hairless mouse by a method in which a large dose of [3H]phenylalanine (150 mumol/100 g body wt.) is administered via the tail vein. The epidermal free phenylalanine specific radioactivity rapidly rose to a plateau value which by 10 min approached that of plasma, after which it declined. This dose of phenylalanine did not of itself alter protein synthesis rates, since incorporation of co-injected tracer doses of [3H]lysine and [14C]threonine was unaffected. The fractional rate of protein synthesis obtained for epidermis was 61.6%/day, whereas values for liver and gastrocnemius muscle in the same group of mice were 44%/day and 4.8%/day respectively. When expressed on the basis of RNA content, the value for epidermis (18.6 mg of protein/day per mg of RNA) was approx. 3-fold higher than those for liver and gastrocnemius muscle. Topical administration of 0.1% triamcinolone acetonide increased the epidermal fractional protein synthesis rate by 33% after 1 day and by 69% after 7 days, compared with vehicle-treated controls. These effects were entirely accounted for by the increase in protein synthesis rates per mg of RNA. RNA/protein ratios were unaffected by this treatment.

Radiolabeling of Fibrinogen Using the Iodogen Technique

1981 ◽  
Vol 46 (03) ◽  
pp. 593-596 ◽  
Author(s):  
Linda C Knight ◽  
Andrei Z Budzynski ◽  
Stephanie A Olexa
Keyword(s):  
Specific Radioactivity ◽  
Oxidizing Agent ◽  
Iodine Monochloride ◽  
Human Fibrinogen

SummaryThe properties of human fibrinogen labeled with 125-Iodine using Iodogen (1, 3, 4, 6-tetrachloro-3α, 6α-diphenylglycoluril) as an oxidizing agent were compared with those of an iodine monochloride labeled counterpart. It was found that thrombin clottability, binding to staphylococci, the relative specific radioactivity of the Aα, Bβ, and γ chains and in vivo clearance from plasma in rabbits were the same in these two labeled fibrinogen preparations. Labeling efficiency was higher when iodogen was used. It is concluded that human fibrinogen labeled with radioiodine using the Iodogen technique is suitable for studies in vitro and in vivo.

Absolute SPECT/CT quantification of cerebral uptake of 99mTc-HMPAO for patients with neurocognitive disorders

2016 ◽  
Vol 55 (04) ◽  
pp. 158-165 ◽  
Author(s):  
Friedrich Welz ◽  
James Sanders ◽  
Torsten Kuwert ◽  
Juan Maler ◽  
Johannes Kornhuber ◽  
...  
Keyword(s):  
Tissue Concentration ◽  
Tracer Uptake ◽  
Planar Imaging ◽  
Quantitative Spect ◽  
Dementia Patients ◽  
Hmpao Spect ◽  
Patient Groups ◽  
The Absolute ◽  
99Mtc Hmpao

SummaryIt was reported from planar imaging studies that the cerebral uptake of injected 99mTc-HMPAO activity is about 4–7% in humans. Recent work has shown that modern SPECT/ CT devices are able to quantify the tissue concentration of radioactivity in vivo in absolute units (Bq/ml), while avoiding the limitations of planar techniques. The aims of this study were (a) to determine the cerebral uptake of 99mTc-HMPAO in absolute units in SPECT/CT, (b) to investigate potential differences in absolute tracer uptake for patients suspected of dementia. Patients, methods: We performed 99mTc-HMPAO SPECT/CT in 65 patients with suspected dementia. 99mTc-HMPAO uptake was determined using a previously published quantitative SPECT/CT protocol. The absolute HMPAO uptake and the results of a regionalized analysis were compared for MMSE and NINCDS-ADRDA based patient groups. Results: The mean absolute uptake of 99mTc-HMPAO for our patient population was 4.3 ± 0.8% of the injected dose. The uptake, as well as the regionalized analysis yielded significantly different results for low ( 23) and high (>23) MMSE groups and also for some of the NINCDS-ADRDA groups. Conclusion: Our results show that the absolute cerebral uptake of 99mTc-HMPAO is in the range of previously reported results, obtained by planar techniques. Absolute uptake is significantly different between the patient groups.

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