Search PubMed⌕ Search

Biomedical subjects

C B Berde

Publications and source records attributed to C B Berde.

At least 73 records · Page 4Linked to original sources
PubMed1984

Effects of free fatty acids on release of superoxide and on change of shape by human neutrophils. Reversibility by albumin.

Release of superoxide from human neutrophils was stimulated by cis-unsaturated fatty acids (e.g. arachidonate, linoleate). All the saturated and trans-unsaturated fatty acids tested were ineffective in this context. Binding of linoleate to neutrophils was biphasic and could be resolved into a linear and a saturable component. The extent of linoleate binding to the saturable component correlated strongly with the amount of O-2 released (r = 0.96). Palmitate, a saturated fatty acid, exhibited only linear binding to neutrophils and the binding was similar to the linear component of linoleate binding. All cis-unsaturated fatty acids tested decreased the fluorescence polarization of cis- and trans-parinaric acid used as membrane probes in suspensions of neutrophils, whereas the saturated fatty acid, myristate, increased the polarization. Fatty acids which stimulated O-2 release induced morphological changes (i.e. evaginations) in neutrophils, whereas the inactive fatty acids did not affect the cellular morphology. Effects on both the cell morphology and superoxide release were reversed by treatment of the cells with delipidated albumin. These data are discussed in relation to recent reports concerning the effects of free fatty acids on various biochemical systems.

Arachidonic Acid↗
PubMed1984

Bilirubin binding in the plasma of newborns: critical evaluation of a fluorescence quenching method and comparison to the peroxidase method.

Bilirubin binding affinities and capacities and apparent unbound ("free") bilirubin levels were determined in serum samples from 47 high-risk newborns, in 22 samples of cord serum, and in serum samples from 15 Greek children with marked hyperbilirubinemia, by both fluorescence quenching and peroxidase methods. The free fatty acid:albumin molar ratio was also determined for serum samples from high-risk newborns. In vitro and in vivo measurements suggest that free fatty acids are rarely present at levels that produce significant displacement of bilirubin, which is in agreement with previous studies. The two bilirubin binding assays showed only fair correlation with sizable discrepancies for many specimens. Technical difficulties inherent in the fluorescence quenching method and possible sources of error are discussed. Our observations suggest that routine application of these two assays as the primary criterion for therapeutic intervention (e.g., exchange transfusion) is premature.

Bilirubin↗
PubMed1983

Gel to liquid-crystalline phase transitions of aqueous dispersions of polyunsaturated mixed-acid phosphatidylcholines.

The thermotropic properties of aqueous dispersions of synthetic mixed-acid polyunsaturated 1,2-diacyl-3-sn-phosphatidylcholines (PC) have been studied by differential scanning calorimetry. The gel to liquid-crystalline phase transition temperature (Tc) of 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine (SLPC) was -16.2 +/- 1.6 degrees C (means +/- SD, nine dispersions, three separate synthetic preparations); that for a preparation of 1-stearoyl-2-linolenoyl-PC (SLnPC) was -13 degrees C and for a preparation of 1-stearoyl-2-arachidonoyl-PC (SAPC) was -12.6 +/- 1.0 degrees C (three dispersions, one preparation). The temperatures of maximum heat flow (Tmax) for the lipid transitions were -14.4 +/- 1.3, -11, and -10.7 +/- 0.9 degrees C and the enthalpies were 3.3 +/- 1.0, 6.6, and 5.3 +/- 1.8 kcal X mol-1 for SLPC, SLnPC, and SAPC, respectively. The transition temperatures and enthalpies are rationalized on the basis of existing data on the effect of double-bond position on Tc and are interpreted with the use of a statistical mechanical model. The trend of the transition temperatures with the introduction of multiple double bonds reflects opposing effects due to increased molecular area and decreasing degrees of freedom of rotation about carbon-carbon bonds.

Calorimetry, Differential Scanning↗
PubMed1980

A theory of the effects of head-group structure and chain unsaturation on the chain melting transition of phospholipid dispersions.

We have developed statistical mechanical descriptions of the effects of head-group structure and acyl chain unsaturation on the chain melting phase transition of aqueous dispersions of bilayers containing glycerophosphocholines and glycerophosphoethanolamines. The theoretical framework is an extension of the model of Jacobs et al. [Jacobs, R. E., Hudson, B. S., & Andersen, H. C. (1975) Proc. Natl. Acad. Sci. U.S.A. 72, 3993]. There are several systematic trends in the experimental transition data for various types of phospholipids. Assumptions about the physical origins of these trends were incorporated into statistical mechanical models, which were used to calculate transition temperatures and enthalpies. The extent to which the calculated results of a model reproduce the experimental trends is taken as a measure of the validity of the assumptions on which the model is based. We found that the gross differences among the transition temperatures of phospholipids with two saturated chains, two trans-unsaturated chains, two cis-unsaturated chains, and one cis-unsaturated and one saturated chain can all be explained in terms of the effect of the double bonds on molecular shape and the subsequent effect of shape on the ability of molecules to pack together into a low-energy state at high density. The dependence of transition temperature on the location of the double bond in cis-unsaturated molecules can be understood on the same basis. The differences between the transition temperatures of glycerophosphocholines and glycerophosphoethanolamines with the same hydrocarbon chains can be explained in terms of a larger intermolecular attraction (or smaller repulsion) for the latter than for the former. These differences depend on the presence or absence of unsaturation in the hydrocarbon chains in a way that is consistent with the postulate that hydrogen bonding between glycerophosphoethanolamines is responsible for the differences.

Chemical Phenomena↗
PubMed1980

Use of the conjugated polyene fatty acid, parinaric acid, in assaying fatty acids in serum or plasma.

We describe a method for rapidly assaying fatty acid concentrations in plasma or serum. This method is particularly appropriate for monitoring increased concentrations of fatty acids that may be present during intravenous lipid infusion, especially in neonates. Binding cisparinaric acid (9, 11, 13, 15-cis-trans-trans-cis-octadecatetraenoic acid) to albumin shifts the absorption spectrum of the acid. If fatty acids are present in serum, they will compete with parinaric acid for binding, changing the extent of this absorption shift. The measurement requires a spectrophotometer, 30 microL of serum or plasma, and knowledge of the sample's albumin concentration.

Bilirubin↗
PubMed1979

Human alpha-fetoprotein. Fluorescence studies on binding and proximity relationships for fatty acids and bilirubin.

The binding of bilirubin and the polyene fatty acids cis-parinaric acid and cis-eleostearic acid to human alpha-fetoprotein was studied using fluorescence quenching and fluorescence enhancement techniques. alpha-Fetoprotein has three fatty acid binding sites of decreasing affinity (association constants 2.1 x 10(7) M-1 9.1 X 10(5) M-1, and 1.4 x 10(5) M-1) and one relatively strong and one relatively weak bilirubin binding site (association constants 1.1 x 10(7) M-1 and 1.8 x 10(5) M-1). These association constants are slightly weaker than the corresponding association constants for binding to human albumin. Competition experiments failed to show preferential binding of polyunsaturated fatty acids. Fluorescence quenching was used to determine 11 ligand-ligand and ligand-tryptophanyl residue distances. Each of these 11 calculated distances (ranging from 19 A to 32 A) was within 5 A of the corresponding distances measured previously for human albumin (Berde, C.B., Hudson, B.S., Simoni, R.D., and Sklar, L.A. 1979, J. Biol. Chem. 254, 391-400). Thus, in addition to previously described sequence homology, immunologic cross-reactivity, and other similarities, human albumin and human alpha-fetoprotein have functional and geometric homologies.

Bilirubin↗
PubMed1979

Human serum albumin. Spectroscopic studies of binding and proximity relationships for fatty acids and bilirubin.

Binding and proximity relationships of hydrophobic ligands on human serum albumin have been studied using absorption, fluorescence, circular dichroism, and electron paramagnetic resonance spectroscopy. The ligands studied were bilirubin, two conjugated linear polyene fatty acids, cis-parinaric acid and cis-eleostearic acid, and three nitroxide derivatives of stearic acid with doxyl groups at positions 5, 10, and 12, respectively. Binding of polyene fatty acids was monitored by absorption peak shifts, induced circular dichroism, enhancement of fluorescence, and energy transfer between albumin's single tryptophanyl residue and the polyene chromophore. Induced circular dichroism studies indicate excitonic ligand-ligand interaction between bound fatty acids. Fluorescence enhancement of cis-parinaric acid was analyzed using a stepwise multiple equilibrium model, and six binding constants in the range 10(8) to 10(6) M-1 were obtained, in agreement with previous measurements for other fatty acids. The temperature dependence of the equilibrium constants indicates that the binding enthalpy is nearly zero. Fluorescence energy transfer was similarly used to quantitate bilirubin binding to albumin. Energy transfer, nitroxide quenching of fluorescence, and electron paramagnetic resonance spectroscopy were used to elucidate binding geometries which support and extend proposed structural models for albumin. It is suggested that the first two fatty acids bind side-by-side in an antiparallel fashion in domain III of human serum albumin.

Bilirubin↗
PubMed1977

Activation of purified 3-hydroxy-3-methylglutaryl-CoA reductase by phospholipids.

3-Hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase), the enzyme that catalyzes the rate-limiting step in cholesterol biosynthesis, has been purified by two previously reported procedures. Enzyme purified by the method of Heller, R. and Shrewsbury, M. (1976) J. Biol. Chem. 251, 3815-3822) shows up to 3-fold enhancement of activity by various types of lipid dispersions while the enzyme purified by the procedure of Tormanen et al. ((1976) Biochem. Biophys. Res. Commun. 68, 754-762) shows no activation. These results suggest that interaction with microsomal membrane lipids may be important in determining the activity of this enzyme. Analysis of bound lipid showed that enzyme prepared by the procedure of Tormanen contained at last 50 times as much phospholipid on a weight basis as enzyme prepared by Heller and Shrewsbury. Analysis of both preparations by gel-electrophoresis indicates that enzyme activities of the two comigrate, but in neither case does activity coincide with the major protein species.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Continuous caudal anesthesia for inguinal hernia repair in former preterm infants.

STUDY OBJECTIVE: To determine the feasibility of continuous caudal anesthesia with 2-chloroprocaine in conscious former preterm infants undergoing inguinal hernia repair. DESIGN: Prospective study. SETTING: University-affiliated children's hospital. PATIENTS: Ten former preterm infants, ASA physical status II and III, who were 35 to 49.5 weeks postconceptional age at the time of surgery. INTERVENTIONS: Caudal anesthesia was administered via an indwelling catheter using a loading dose of 1 ml/kg (30 mg/kg) of 3% 2-chloroprocaine, followed by incremental doses of 0.3 ml/kg (9 mg/kg) to achieve a level of T4 to T2. The block was maintained by a minimum infusion rate of 30 mg/kg/hr (1 ml/kg/hr) of the same local anesthetic solution. MEASUREMENTS AND MAIN RESULTS: The mean cumulative dose of 2-chloroprocaine was 2.8 +/- 1.0 ml/kg/hr (84 +/- 30 mg/kg/hr) infused over a mean duration of 95 +/- 35 minutes. Serum cholinesterase concentration and plasma 2-chloroprocaine concentration were measured in five infants. CONCLUSIONS: Three percent 2-chloroprocaine can be used effectively for continuous caudal anesthesia in conscious, former preterm infants for inguinal hernia and penoscrotal surgical procedures lasting 85 to 170 minutes.

Anesthesia, Caudal↗
PubMedDate not supplied

Management of tracheobronchial and esophageal foreign bodies in children: a survey study.

STUDY OBJECTIVE: To assess the current anesthetic management for aspiration of a foreign body into the airway and esophagus of a young child. DESIGN: Questionnaire study. MEASUREMENTS AND MAIN RESULTS: A questionnaire regarding choice of induction technique in a variety of foreign body clinical scenarios was sent to 1,342 anesthesiologists, all members of the Society for Pediatric Anesthesia. The foreign body, either a coin (penny) or a safety pin (open), was positioned on radiography in a variety of anatomic locations. Depending on the foreign body location, the patient was either asymptomatic or exhibited symptoms. Participants indicated their choice of induction for each situation. Of the 1,342 questionnaires mailed, there were 838 respondents (62.4%). Coins and pins in the gastroesophageal tract were managed mostly by a rapid-sequence induction (p < 0.001). Coins and pins at all levels in the tracheobronchial tree were managed most often by a mask induction with no cricoid pressure (p < 0.001). Although 14.5% of respondents chose awake and sedated technique for a foreign body in the supraglottic area, few chose this technique for a foreign body in other locations. The type of object did not affect the choice of drugs for induction of anesthesia in most anatomic locations. Respondents with limited pediatric anesthesia experience used inhalation induction much less often than did those with more experience. Multiple-logistic regression analysis showed that both number of years in practice and type of practice (university, private, hybrid) were predictors for the induction. CONCLUSIONS: These data indicate that inhalation induction is favored most often for removal of foreign bodies in the airway, while intravenous induction is preferred for removal of foreign bodies in the gastroesophageal tract. In addition, practice type, greater percentage of time spent in pediatric anesthesia, and greater experience are related to a higher likelihood of inhalation induction.

Anesthesia↗
PubMedDate not supplied

The local anesthetic properties and toxicity of saxitonin homologues for rat sciatic nerve block in vivo.

BACKGROUND AND OBJECTIVES: Saxitoxin and its homologues are naturally occurring compounds that block the sodium channel with high potency. They have the potential for providing prolonged duration local anesthesia when coinjected with vasoconstrictors or conventional local anesthetics and are devoid of local neurotoxicity. Here, we compare sciatic nerve block with saxitoxin to those with neosaxitoxin, decarbamoyl saxitoxin, and tetrodotoxin (TTX), in a search for even safer compounds. METHODS: Rats received percutaneous sciatic nerve block with toxins. The compounds were compared in terms of lethality, onset and duration of action for thermal analgesia (hot-plate testing), and motor block (weight-bearing). Data were expressed as medians with 25th and 75th percentiles, and median effective concentrations were determined. RESULTS: The median concentrations at which analgesia of 60 minutes duration was achieved were neosaxitoxin, 34+/-2 micromol/L; saxitoxin, 58+/-3 micromol/L; TTX, 92+/-5 micromol/L; and decarbamoyl saxitoxin, 268+/-8 micromol/L. Similar trends were observed for other measures of effectiveness (block duration of 90 minutes, maximal block), and for lethality so that the therapeutic indices were similar. No toxin had a marked predominance of sensory or motor block. The potency of TTX was intermediate between those of the saxitoxins, and its therapeutic index was slightly better. No difference was observed in time to onset of nerve blockade among the toxins. CONCLUSIONS: Substitutions on the saxitoxin nucleus result in large differences in incidence and duration of block, and toxicity. The therapeutic indices of the saxitoxins are similar; that of TTX is slightly better.

Anesthetics, Local↗