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C C Schwartz

Publications and source records attributed to C C Schwartz.

At least 19 recordsLinked to original sources
PubMed1991

Plasma 1-palmitoyl-2-linoleoyl phosphatidylcholine. Evidence for extensive phospholipase A1 hydrolysis and hepatic metabolism of the products.

1-Palmitoyl-2-linoleoyl phosphatidylcholine (PLPC) labeled in either the choline, glycerol, palmitate, or linoleate component in reconstituted rat high density lipoprotein (rHDL), was administered by vein to rats with bile fistula and taurocholate infusion. PLPC disappeared from plasma in a monoexponential fashion with a half-life of 50 min. A small fraction, about 14%, of PLPC disappearance was due to removal of linoleate from the sn-2 ester bond to form plasma cholesterol esters, presumably by lecithin-cholesterol acyltransferase. Otherwise, nearly all of the PLPC components that disappeared from blood in 1 h were recovered in the liver. The choline, glycerol, and linoleate components appeared predominantly in hepatic phosphatidylcholine (PC). These three components remained together in the liver with similar fractions of each in individual PC molecular species, most notably 1-stearoyl-2-linoleoyl-PC and dilinoleoyl-PC as well as PLPC. However, the palmitate component was spread among hepatic triglyceride, free fatty acid, other phospholipids, and all palmitate-containing molecular species of PC. Less than 2% of any administered PLPC component appeared in 1-stearoyl-2-arachidonyl-PC, the major species by mass in the liver. The palmitate component from plasma PLPC appeared in biliary PC at a more rapid rate than glycerol and linoleate components; the latter components appeared in bile in identical fashion. The results show that about two-thirds of plasma PLPC disappearance is due to phospholipase A1 hydrolysis, probably hepatic lipase. The putative produce, 2-linoleoyl-lysoPC, is efficiently reacylated with a saturated fatty acid in the liver, conserving PC.

Animals↗
PubMed1991

Effects of R51163 on intake and metabolism in moose.

R51163, a newly synthesized purine alkyl piperidine that produces reliable sedation in cattle, was tested in five adult bull moose (Alces alces). Compared with controls, all animals dosed with 0.4 mg/kg BW ate significantly (P less than 0.05) less dry matter for at least 1 wk after treatment. Median estimates of resting metabolism, measured the day of injection, did not differ between treatment and control groups, although the coefficient of variation was almost two times larger for drugged (15%) versus control (8%) individuals. Dose response was allometric, with larger animals exhibiting longer effects.

Animals↗
PubMed1990

Dehydroepiandrosterone and related steroids induce multilamellar lipid structures in cultured human endothelial cells.

Pharmacologic doses of dehydroepiandrosterone (DHEA), a steroid hormone produced naturally by the adrenal cortex, may lower plasma lipoprotein levels in humans and reduce the severity of experimental atherosclerosis in rabbits. Effects of DHEA on cells of the vascular wall, particularly endothelial cells (EC), which are in direct contact with the plasma, have not been documented. The authors have found that micromolar doses of DHEA induce a consistent and reversible morphologic change in cultured EC derived from the human umbilical vein. During 24 hours of exposure to DHEA, cultured EC became loaded with phase-dense, perinuclear cytoplasmic granules, which persisted while DHEA remained in the culture medium. Certain steroids related to DHEA, particularly 17-ketosteroids, also induced perinuclear cytoplasmic granules. The granules lost their phase-density after fixed monolayers were extracted using ethanol or methanol. The granules did not form in media made with lipoprotein-deficient serum, suggesting that serum lipoproteins were involved in formation of the granules. Ultrastructurally, the granules were identical to multilamellar lipid structures, a type of pleomorphic lipid-containing lysosome found in foam cells. The granules were identified as lysosomes by positive reaction for acid phosphatase. The mechanism by which DHEA induces formation of lysosomal lipid structures remains to be determined.

Animals↗
PubMed1986

Bile acid production in human subjects: rate of oxidation of [24,25-3H]cholesterol compared to fecal bile acid excretion.

Bile acid production has been quantitated in seven subjects by methods that compare the results of two independent approaches, namely, quantitation of cholesterol side-chain oxidation and fecal bile acid excretion. Six hypertriglyceridemic (HT) subjects and one normolipidemic control were studied by both techniques. A further control subject was studied by the cholesterol side-chain oxidation method alone. Cholesterol side-chain oxidation was quantitated by measuring the appearance of 3H2O after intravenous administration of [24,25-3H]cholesterol, using multicompartmental analysis of plasma cholesterol and [3H]water specific activity. Body water kinetics were independently defined by use of oral D2O. Two HT subjects were restudied while they were taking cholestyramine, 16 g/day. In all ten studies, multicompartmental analysis closely simulated the observed appearance of 3H2O. Values obtained for bile acid production suggest that cholesterol oxidation, or bile acid input, was significantly greater than fecal bile acid output in the HT subjects (P less than 0.05). Cholesterol side-chain oxidation rates in the two normal subjects were lower than those encountered in HT subjects, being similar to published values for normal subjects both for bile acid synthesis as determined by isotope dilution kinetics and fecal bile acid excretion. Studies conducted with two, synthetically different, preparations of [24,25-3H]cholesterol indicated that, in one of the two preparations, approximately 20% of the tritium label was at positions proximal to C24. In the other preparation examined, all of the tritium was located at, or distal to, C24. Further studies revealed that 0.055-0.24% of the dose was present as labile tritium by virtue of its appearance as 3H2O following in vitro incubation with human plasma. Provided these isotope effects are taken into account, multicompartmental analysis of plasma [24,25-3H]cholesterol and body water appears to be a useful technique for quantitating cholesterol oxidation in human subjects.

Adult↗
PubMed1984

Blue-green color and composition of Stejneger's beaked whale (Mesoplodon stejnegeri) milk.

Two hundred ml of milk were obtained from a lactating Stejneger's beaked whale stranded at Ninilchik, Alaska on 21 Oct, 1980. Total solids (41%) were similar to values reported for sperm and belukha whales, while fat (17%) was half as great and crude protein (17%) was 2-4 times greater than in milk of these species. Lactose was not detected. Calcium (0.22%) was greater than reported for pigmy sperm whales but less than for blue whales. Phosphorus (0.07%) was less than for any of the above species. Sodium and potassium concentrations were 0.13% and 0.11%, respectively. Values (microgram/g) for other elements analyzed (magnesium, 42; iron, 35; copper, 2.6; zinc, 1.5; manganese, 0.3; selenium, 0.36) have not been reported for whale milk. Based on SDS-gel electropherograms, this whale milk did not contain a whey protein corresponding to cattle milk alpha-lactalbumin. A blue-green pigment in the milk was identified as biliverdin.

Animals↗
PubMed1984

Isolation of chlordecone binding proteins from pig liver cytosol.

Cytosolic proteins may play an important role in the transport of water insoluble substances through the cytosol to various subcellular locations. The binding of chlordecone (CD) to pig liver cytosolic proteins was studied after the simultaneous administration of [14C]CD and [3H]cholesterol via the portal vein. The isolation of chlordecone binding proteins (CDBPs), from liver cytosol consisted of repeated ultracentrifugation, ammonium sulfate fractionation, and chromatography on Bio-Gel A 0.5m, carboxymethyl cellulose (CMC), and Sephadex G-100. Three proteins retained [14C]CD after elution from the CMC column. CDBP I and CDBP II also retained [3H]cholesterol through this stage of purification, while CDBP III did not. The molecular weights, estimated by Sephadex G-100 gel filtration, were 33,500 and 67,000 for CDBP IA and CDBP IB, 49,000 for CDBP II, and 44,000 for CDBP III. Since dissociation of bound cholesterol could not be avoided during the purification procedures, binding of cholesterol to the CDBPs eluted from Sephadex G-100 was investigated. Incubation of CDBPs with [3H]cholesterol resulted in a 2000-fold increase of 3H associated with CDBP II, an 800-fold increase with CDBP IA, a 100-fold increase for CDBP IB, and a 300-fold increase for CDBP III. The isolation characteristics, molecular weights, and cholesterol binding properties of the CDBPs are compared with cytosolic cholesterol binding proteins previously isolated. The high specific activity binding of both CD and cholesterol by CDBP I and CDBP II suggests that CD and cholesterol share a common transport pathway in the liver cytosol.

Animals↗
PubMed1984

High-density lipoproteins decrease the biliary concentration of chlordecone in isolated perfused pig liver.

Chlordecone (CD) is an organochlorine pesticide associated with albumin and high-density lipoproteins (HDL) in the plasma. It is found in higher concentrations in the liver than in other tissues and is excreted in the bile. The influence of plasma HDL on the biliary excretion of CD was studied using isolated pig liver perfused with a Krebs-Ringer bicarbonate solution containing albumin, dextrose, and pig red blood cells. Within 5 min after administration into the perfusion medium of [14C]CD bound to albumin or to HDL, only 13% of the [14C]CD dose remained in the perfusate, showing that CD is rapidly taken up by the liver. After 60 min the plasma concentration was constant at 0.008% dose/ml when [14C]CD was administered bound to albumin in the absence of HDL and at 0.004% dose/ml when administered bound to HDL. The mean concentration of CD in the bile was higher when CD was administered bound to albumin in the absence of HDL (0.039% dose/ml) than when it was administered bound to HDL (0.010% dose/ml). The elimination rate constant of CD from the liver into the bile was 0.007/min whether CD was administered bound to albumin or to HDL. The addition of HDL to the perfusion system after the administration of albumin-bound CD resulted in lower biliary CD concentrations. The results suggest that HDL affects the distribution of CD between the perfusate and liver and between liver and bile. In both cases, distribution toward the liver is favored.

Animals↗
PubMed1984

Baseline body temperatures, heart rates, and respiratory rates of moose in Alaska.

Baseline body temperatures (BT), heart rates (HR) and respiratory rates (RR) were obtained from Alaskan moose (Alces alces gigas Miller) at the Moose Research Center (MRC), Alaska. Excitability, seasons and drugs influenced the values to varying degrees. Excitability was the most influential factor. Safe expected ranges were: BT 38.4 to 38.9 C, HR 70 to 91 beats/min (b/min), and RR 13 to 40 respirations/min (r/min). These ranges incorporated all seasons, a central nervous system depressant drug and a paralyzing drug. Values which may be considered critical and an indication that corrective action should be taken include: BT 40.2 C, HR 102 b/min, and RR 40 r/min. It is recommended that persons trained in monitoring vital signs be on hand during moose capture and immobilization procedures.

Alaska↗
PubMed1983

Chlordecone metabolism in the pig.

The biotransformation of chlordecone (CD) to chlordecone alcohol (CDOH) occurs in man and gerbils but not in rats, guinea pigs and hamsters [1, 2]. Because of the species differences in CDOH formation and the need for a suitable animal model, pigs were administered CD by intraperitoneal (i.p.) injection. Plasma, gallbladder bile, hepatic bile, liver and feces were collected and analyzed by gas chromatography for CD metabolites. CDOH was present in bile and feces with up to 85% conjugated in the bile but only 15% was conjugated in the feces. Up to 20% of the CD in plasma and bile and less than 3% in feces was in the conjugated form. Both reduction and conjugation of CD in the pig are similar to those in man.

Animals↗
PubMed1982

Preferential binding of chlordecone to the protein and high density lipoprotein fractions of plasma from humans and other species.

The preferential distribution of the relatively nonpolar pesticide chlordecone (CD) to liver rather than to fat tissues in humans suggests that it may be transported in plasma differently from other organochlorine pesticides. The plasma binding of [14C] CD was investigated in vitro in human, rat, and pig plasma and in vivo in rat plasma. Protein and lipoprotein fractions were separated by serial ultracentrifugation. Heparin-manganese precipitation and agarose gel electrophoresis were also carried out to determine whether separation techniques altered CD binding to plasma components. In human plasma, the distribution of [14C] CD among proteins and high density, low density, and very low density lipoproteins (HDL, LDL, and VLDL) was 46, 30, 20, and 6%, respectively. The distribution of cholesterol in the same plasma fractions was 4, 20, 63, and 7%, respectively. In the pig and rat the order of binding was similar to that in humans, with protein greater than or equal to HDL greater than LDL greater than or equal to VLDL. Separation by heparin-Mn precipitation confirmed the results obtained by ultracentrifugation. The distribution of [14C] CD in rat lipoprotein was similar whether the CD was administered in vivo or incubated with plasma in vitro, with approximately 80% bound to HDL, 11% to LDL, and 9% to VLDL in either case. Agarose gel electrophoresis of plasma-bound [14C] CD indicated that albumin was the major component of the protein fraction responsible for CD binding. Preferential binding of CD by albumin and HDL may explain its unusual tissue distribution compared to other organochlorine pesticides such as aldrin and dieldrin, which bind preferentially to VLDL and LDL and distribute preferentially to fat tissues.

Animals↗
PubMed1982

Central role of high density lipoprotein in plasma free cholesterol metabolism.

This study was designed to provide direct information on the in vivo metabolism in man of free (unesterified) cholesterol in the major lipoprotein classes. Five human subjects were administered one or two (simultaneous) of the following; [2-(14)C] mevalonic acid, high density lipoprotein (HDL)-free [(14)C] cholesterol, low density lipoprotein (LDL)-free [(14)C] cholesterol, and very low density lipoprotein (VLDL)-free [(3)H]cholesterol. Blood was then obtained at frequent intervals for at least 9 h, and the alpha(HDL) and beta(LDL + VLDL) lipoproteins were quickly separated by heparin-manganese precipitation to prevent ex vivo exchange of free cholesterol. After the administration of [(14)C]mevalonic acid the specific activity (disintegrations per minute/micromole) of free cholesterol in the alpha- and beta-lipoproteins increased for 3 h. During this period the alpha-free cholesterol specific activity was higher than the beta specific activity. After administration of VLDL and LDL labeled with free cholesterol, the alpha-free cholesterol specific activity reached a peak value within 20 min, at which time it was considerably lower than the beta-free cholesterol specific activity. When HDL labeled with free cholesterol was administered, a precursor product relationship was observed between the alpha-free cholesterol (precursor) and beta-free cholesterol (product) specific activities.A multicompartmental model was developed that contained the simplest structure necessary to fit all of the data obtained. The kinetic analysis revealed the presence of extensive exchange (20-85 mumol/min) of free cholesterol between HDL and a tissue pool(s) enriched with newly synthesized free cholesterol. It was found that virtually all (>95%) of the free cholesterol in the beta-lipoproteins (LDL+VLDL) cycles directly through HDL. The free cholesterol in LDL appears to behave in the same fashion as the free cholesterol in VLDL. The results show that there are marked differences in the kinetic behavior of the free cholesterol fractions of alpha- and beta-lipoproteins. There is extensive recycling of free cholesterol between HDL and tissue pools, and between HDL and the beta-lipoproteins; this recycling has been quantitated. The findings support the view that in vivo, the free cholesterol in HDL plays a central role in exchange reactions and in the vascular-tissue cholesterol transport system.

Aged↗
PubMed1981

Beta-endorphin levels in blood from selected Alaskan mammals.

Blood samples were analyzed for beta-endorphin from 43 non-torpid black bear (Ursus americanus), 8 torpid black bear, 3 non-torpid brown bear (Ursus arctos), 14 moose (Alces alces), 6 mountain goats (Oreamnus americanus) and 30 Steller sea lions (Eumetopias jubatus). Beta-endorphin levels were detected in all species sampled and there were no significant differences in levels among non-torpid black bear, brown bear and sea lions. Also, no differences were detected between moose and mountain goats, but all other comparisons were significantly different (P less than 0.001). Torpid black bear had higher levels than all other groups. Moose and mountain goats had the lowest levels. The possibility of beta-endorphin influencing behavior and physiology of mammals is discussed.

Alaska↗
PubMed1978

Preferential utilization of free cholesterol from high-density lipoproteins for biliary cholesterol secretion in man.

High- and low-density lipoproteins carrying free cholesterol labeled with 3H or 14C were administered to a patient with a bile fistula. The free cholesterol from high-density lipoproteins was more rapidly incorporated into biliary cholesterol than the free cholesterol from low-density lipoproteins. These findings show that the liver in man selectively utilizes and secretes the free cholesterol from a particular lipoprotein.

Aged↗