Phospholipid liposomes acquire apolipoprotein E in atherogenic plasma and block cholesterol loading of cultured macrophages

A single infusion of phospholipid liposomes promptly and persistently abolished the ability of hypercholesterolemic rabbit plasma to cause cholesteryl ester loading in cultured macrophages. This phospholipid enrichment of plasma caused moderate stimulation of cellular cholesterol efflux and, unexpectedly, almost complete inhibition of cellular uptake of beta-very low density lipoprotein (beta-VLDL), the major cholesteryl ester-rich particle in hypercholesterolemic rabbit plasma. Cell viability and LDL receptor activity were unaffected. Incubation of liposomes with beta-VLDL resulted in transfer of apolipoprotein-E (apoE) to the liposomes; reisolated apoE-phospholipid liposomes then competed efficiently for cellular apoprotein receptors. Thus, a major mechanism by which phospholipid infusions result in diminished accumulation of cholesteryl ester in cultured macrophages is by blocking cellular uptake of beta-VLDL. The liposomes deplete beta-VLDL of apoE, then compete for receptor-mediated uptake. These results suggest a novel mechanism contributing to the known antiatherogenic effect of phospholipid infusions: infused liposomes acquire apoE, then block uptake of atherogenic lipoproteins by arterial wall macrophages.

Ceftazidime does not enhance cyclosporin-A nephrotoxicity in febrile bone marrow transplantation patients

Ceftazidime was used as monotherapy for 30 febrile episodes in 28 patients, who underwent allogeneic bone marrow transplantation and who were treated concomitantly with the immunosuppressive agent cyclosporin-A. Ceftazidime did not enhance the well established nephrotoxicity of cyclosporin-A as measured by serum creatinine levels or creatinine clearance. Although an increasing number of Gram-positive infections in these patients warrants vigilance, ceftazidime as initial empirical monotherapy proved to be successful in 95% of all febrile post-transplantation patients. All Gram-negative and 69% of the Gram-positive infections were cured with ceftazidime alone. The overall clinical cure rate was 72%, with microbiological clearance in 63%. This compares favourably with aminoglycoside containing schedules and avoids the aminoglycoside associated nephrotoxicity.

Ceftazidime alone for treating Pseudomonas aeruginosa septicaemia in neutropenic patients

Twenty-nine patients with primary or secondary hypoplastic bone-marrow were treated successfully with ceftazidime alone for established septicaemia caused by Pseudomonas aeruginosa of which 38% strains were gentamicin-resistant . All the patients were neutropenic at the start of therapy; most were cured with microbiological confirmation before the bone marrow had regenerated. One patient died of cerebral haemorrhage due to profound thrombocytopenia without evidence of infection at autopsy. Significant toxicity was not observed. Ceftazidime alone is, therefore, a safe and effective treatment for infections caused by this organism even in the neutropenic patient.

Recognition of vesicular lipoproteins by the apolipoprotein B,E receptor of cultured fibroblasts

Vesicular lipoproteins (e.g., lipoprotein-X) are found in plasma in cholestasis or following infusion of Intralipid or phospholipid. To investigate the metabolism of vesicular lipoproteins, we isolated them from the plasma of subjects with cholestasis or following chronic or single Intralipid infusion. Cholestasis and chronic Intralipid therapy were found to be associated with elevated plasma concentrations of apoE, as determined by radioimmunoassay. Vesicular lipoproteins purified from each of the three types of plasma contained apoE, as well as other proteins. In cholestasis, in which levels of apoE were up to five times normal, a major portion of the plasma apoE was on vesicular lipoproteins. Normalized for apoE content, all preparations of vesicular lipoproteins displaced 125I-labeled LDL from apoB,E receptors of cultured fibroblasts identically. This displacement was inhibited by monoclonal antibodies that block receptor binding of apoE. Vesicular lipoproteins containing 125I-labeled apoE were internalized and degraded by fibroblasts. Different preparations caused small losses or gains of cellular cholesterol, with appropriate stimulation or suppression of apoB,E receptors. Thus, vesicular lipoproteins contain apoE, and apoE mediates their interaction with the apoB,E receptor. Our results suggest that the catabolism of cholesterol-rich vesicular lipoproteins, formed during cholestasis or following infusions of Intralipid or phospholipid, may be receptor-mediated.

Uptake of endogenous cholesterol by a synthetic lipoprotein

The addition of cholesterol-poor phospholipid liposomes to canine plasma in vivo and in vitro substantially alters the distribution of phospholipids, apoproteins, and, especially, cholesterol. In vivo, intravenously injected phospholipid liposomes remain discrete particles, which are readily distinguished from the normally occurring lipoproteins by their buoyant density and electrophoretic mobility. They acquire unesterified cholesterol from endogenous sources, thereby producing an acute rise in the concentration of this sterol in plasma. The liposomes also accumulate endogenous proteins, one of which is identified as apolipoprotein A-I. In vitro, phospholipid liposomes incubated with plasma acquire unesterified cholesterol and apolipoprotein A-I at the expense of high-density lipoproteins (HDL), the major carrier of cholesterol in normal canine plasma. In exchange, the HDL particles are enriched in phospholipids and become larger. At sufficiently high concentrations, the liposomes nearly completely deplete HDL of its unesterified cholesterol. Thus, there are generated two types of particles, both rich in apolipoprotein A-I and phospholipid, but one (modified HDL) containing mainly esterified cholesterol in its core and the other (modified liposomes) containing mainly unesterified cholesterol at its surface. It is concluded that phospholipid liposomes produce important changes in the distribution of lipids and protein in canine plasma, particularly at the expense of HDL. These changes appear to favor the mobilization of tissue cholesterol into the plasma, and may have application to atherosclerosis.

Teratogenic dose-response relationships of etretinate in the golden hamster

Etretinate (Ro 10-9359; Tigason; 4-methoxy-2,3,6-trimethylphenyl analog of retinoic acid, ethyl ester) was evaluated for teratogenic activity in the Syrian golden hamster. Groups of pregnant hamsters were given a single oral dose of 2.8-88 mg/kg etretinate during the early primitive streak stage of gestation. No signs of maternal intoxication were observed in any of the hamsters given the retinoid and maternal body weight changes throughout gestation were not significantly different from those of the vehicle-treated group. Etretinate administration was associated with a dose-dependent increase in the incidence and severity of malformations. The average fetal body weight was significantly less in litters recovered from dams given 44 or 88 mg/kg of etretinate when compared to the average body weight of fetuses recovered from dams given an equivalent volume of the vehicle. The average crown-rump lengths also were significantly shorter in fetuses taken from the dams given 44 or 88 mg/kg etretinate as compared to the control group. The malformations induced by etretinate administration were similar to those noted following an oral dose of all-trans-retinoic acid (Willhite and Shealy, 1984). A comparison of the dose-response curves for induction of terata following treatment with etretinate or all-trans-retinoic acid revealed that etretinate was twice as potent as a teratogen in the hamster as all-trans-retinoic acid. Teratogenic activity of etretinate in the hamster was achieved at doses (mg/kg body wt) used in patients at current clinical therapeutic levels.

The failure of serum albumin to affect capillary permeability in the isolated rabbit heart

The method of local tissue clearance was used to measure capillary permeability-surface area products (PS) for [3H]inulin and [14C]sucrose in the left ventricular wall of the isolated rabbit heart. As soon as a heart was excised, its coronary arteries were perfused with Ringer solution at 37 degrees for at least 30 min before clearance trials were begun. In paired trials, Ringer perfusion fluid containing 1% bovine serum albumin (Sigma) was compared with protein-free Ringer solution in terms of sucrose PS (PSs), inulin PS (PSi), and the PS ratio (Pi/Ps). With or without protein, the mean Pi/Ps was significantly less than the ratio of the free diffusion coefficients. With the untreated albumin, flow resistance rose markedly, and the PSs of both solutes fell but not Pi/Ps. To remove the unidentified vasoactive contaminant (which apparently resisted dialysis), the albumin was "defatted" by the procedure of R. F. Chen (1967, J. Biol. Chem. 242, 173-181). Defatted albumin (1% in the perfusion fluid) did not affect the volume of distribution (lambda) of sucrose or inulin in the myocardium, the heart rate, coronary flow, flow resistance, PSs, PSi, or Pi/Ps. Apparently bovine serum albumin does not influence capillary permeability in the rabbit heart. A protein effect on permeability, however, could have been missed if it has a long latent period (more than 15 min) or a long persistence (more than 30 min).

A direct bone marrow chromosome technique for acute lymphoblastic leukemia

We describe a direct bone marrow chromosome technique that was developed especially for use in studies of acute lymphoblastic leukemia (ALL). The features responsible for technical improvements include: the use of RPMI 1640 medium, supplemented with 30% fetal calf serum, to support cellular activity during both specimen transport and Colcemid treatment; the processing of only 0.1 ml of sedimented cells or less per centrifuge tube; the exposure of cells to Colcemid for a maximum of 25 min; control of the total time of exposure to hypotonic solution; the use of a steel wire as a stirring rod (fashioned to fit the centrifuge tube) for mixing cells; slide preparation by a specific edging-flaming technique; the natural aging of the slides to achieve optimal drying; and the use of a modified G-banding procedure that employs Wright's stain. This technique has been used in more than 350 cases of ALL and has consistently provided analyzable banded chromosomes, even in hyperdiploid cases with up to 91 chromosomes. It makes the previously recognized morphological difference between metaphases of residual normal cells and those from the leukemic clone less apparent. The edging-flaming technique of slide preparation is the most important component and is especially appropriate for spreading large numbers of chromosomes in ALL.

Structure-activity relationships of retinoids in developmental toxicology. I. Studies on the nature of the polar terminus of the vitamin A molecule

The teratogenic activities of all-trans-retinoyl fluoride, all-trans-3-retinylidene-2,4-pentanedione, all-trans-2-retinylidene-1,3-cyclopentanedione, all-trans-2-retinylidene-5,5-dimethyl-1,3-cyclohexanedione, all-trans-2-retinylidene-5-p-methoxyphenyl-1,3-cyclohexanedione, all-trans-2-retinylidene-1,3-cyclooctanedione, all-trans-5-[2,6-dimethyl-8-(2,6,6-trimethylcyclohexen-1-yl)-1,3, 5,7-octatetrae n-1-yl]tetrazole, ethyl all-trans-9-(exo-2-bicyclo[2.2.1.]heptyl)-3,7-dimethyl-2,4,6,8- nonatetraenoate, ethyl all-trans-4-[2-methyl-4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-1,3- butadien-1-yl]benzoate, 13-cis-N-(4-hydroxyphenyl)retinamide, and 13-cis-N-(2-hydroxyethyl)retinamide were determined in the hamster and compared with that of all-trans-retinoic acid. Administration of a single oral dose of the retinoids failed to induce signs of the hypervitaminosis A intoxication syndrome in any of the dams, and the maternal weight gain was not significantly different from the vehicle control value, except following intubation of the retinamides where maternal weight gain was significantly depressed. All of the retinylidene 1,3-diketones studied here were devoid of significant teratogenic activity. The retinamides failed to induce either an elevated mean litter frequency of malformed fetuses or a syndrome of anomalies similar to that induced by administration of an equimolar dose of all-trans-retinoic acid. All of the other retinoids induced a syndrome of malformations similar to that induced by administration of all-trans-retinoic acid and were associated with a significant increase in the number of litters containing one or more malformed fetuses and an elevated mean litter frequency of malformed fetuses. The teratogenic activity in the hamster of this series of retinoids was independent of structural modifications in either the beta-cyclogeranylidene ring or the polyene chain of the molecule. The results of the present study suggest that the changes in teratogenic activity associated with structural modification of vitamin A at C15 were primarily dependent upon the presence of or biotransformation to a free carboxyl or a moiety with an equivalent pKa at C15, not upon the molecular size of the substituent or the stereochemical position about C13. Since major structural modifications of vitamin A were made without the substantial loss of teratogenic activity, the structural requirements of retinoids for induction of terata were not extraordinarily exacting.

A comparative study of the efficacy of ceftazidime versus cefazolin and tobramycin in patients with acute exacerbations of chronic bronchitis

Fifty-nine adult patients have entered this study. The initial pathogens were eradicated from the infection sites and all except two of the patients who were assessed clinically in the ceftazidime group and 4 cases in the comparative group were cured or improved. No adverse reactions were connected to ceftazidime or to tobramycin and cefazolin.

The pharmacokinetics of ceftazidime in normal and impaired renal function

The concentration of ceftazidime in serum and urine was measured in ten healthy volunteers and 19 patients with renal impairment following a 2 g iv dose of ceftazidime. In impaired renal function the elimination rate of ceftazidime is decreased considerably, whereupon the area under the curve (AUC) rises sharply. Dose reduction factors (DRF) for several degrees of renal function are presented. The urinary recovery decreases with renal function; but therapeutic urine levels can still be detected in patients on dialysis. Patients with renal insufficiency should be given reduced dosage according to a dose reduction factor and according to the table.

Penetration of ceftazidime into human tissue in patients undergoing cardiac surgery

The penetration of ceftazidime into human heart muscle, skeletal muscle, skin, fat and bone was measured in 39 patients undergoing cardiac surgery. Mean serum levels of 70 mg/l were measured 1.5 h after dosing with mean levels of 27 mg/l after 4 h and 5.5 mg/l after 12 h. Tissue levels of ceftazidime were measured up to 280 min after dosing. These levels were high with mean corrected levels after 120 min of 20.0 mg/l in bone, 7.1 mg/l in skin (after 100 min), 9.2 mg/l in fat, 12.7 mg/l in heart muscle and 9.4 mg/l in skeletal muscle. Serum and tissue levels were sufficient to prevent infection by all likely pathogens, including Staphylococcus aureus, 98% of which have a ceftazidime minimum inhibitory concentration of 8 mg/l or less. There were no post-surgical infections.

Randomized study of ceftazidime versus gentamicin plus cefotaxime for infections in severe granulocytopenic patients

A randomized study of gentamicin plus cefotaxime versus ceftazidime alone was performed in 87 patients, with a neutrophil count of less than 1000/mm3 at the start of the treatment. The overall cure rate for the ceftazidime group was 71% and for the gentamicin plus cefotaxime 47%. This difference was shown to be statistically significant at a level of P less than 0.05. The cure rates for the microbiologically proven infections were 90 and 63% respectively. Serious adverse effects, causing preliminary withdrawal of therapy, have not been observed.

Ceftazidime in the treatment of complicated respiratory and urinary tract infections

The efficacy of ceftazidime was examined in 46 patients, 33 with respiratory and 13 with urinary tract infections. Ceftazidime was given following the failure of conventional therapy or when bacteria had been isolated within a week of treatment. It was also used in infections arising as a complication of an indwelling catheter or in emergency situations when alternative antibiotics were inappropriate. Ceftazidime was found to be very successful in the treatment of these infections and only two patients failed to respond clinically, one of these being a patient with an indwelling catheter and one treated as an emergency who had severe underlying pathology. One patient was considered unevaluable because he died of his underlying condition during treatment. Serum levels of ceftazidime are described following im and iv administration of 0.5 and 1 g doses.

Cytogenetic features of acute nonlymphoblastic leukemia in 73 children and adolescents

We examined the leukemia cells of 81 consecutively admitted children and adolescents with acute nonlymphoblastic leukemia (ANLL) to determine the frequency and specificity of chromosomal abnormalities. Karyotypes were obtained for 73 (90%) of the 81 children, and 36 (49%) were abnormal. The modal karyotypes for the cases were tightly clustered in the diploid range; only 5 (7%) were hypodiploid, with 45 chromosomes each, and only 2 (3%) had greater than 50 chromosomes. Specific chromosomal abnormalities in the abnormal karyotypes were compared to morphologic subgroups of ANLL. An 8;21 translocation was found in 6 of 9 cases with M2 morphology but was also found in 1 case with M1 morphology. One of 4 with M3 (progranulocytic) morphology had a 15;17 translocation, and another had a 17q deletion. A structural abnormality in 11q was found in 3 of 7 patients with M5 (monoblastic) morphology, 2 of whom had a 9;11 translocation. The only case of M6 had a 22q-or Philadelphia chromosome in addition to other abnormalities. Statistical analysis of 27 abnormal karyotypes showed preferential structural rearrangement of 8q and 21q. We conclude that, in children as well as adults, specific structural abnormalities are correlated with certain morphologic subgroups of ANLL. However, other chromosomal changes associated with prior mutagenic exposure of adult ANLL were uncommon in children, which may suggest a difference in pathogenesis.

How to make committees work for you

The forum for many hospital managerial concerns is the medical staff committee meeting. This article focuses on the misuses and abuses of committees and offers suggestions for improving their effectiveness. The issues of composition, size, tenure, and formats are discussed, and guidelines for chairman are recommended.

Cytogenetic features of human neuroblastomas and cell lines

We reviewed the banded karyotypes of 24 human neuroblastomas and cell lines to identify any consistent chromosomal abnormalities. Six of the 10 primary tumors and one of the 14 cell lines were studied at this institution. Of the 24 neuroblastomas karyotyped, 20 were near-diploid, one was near-triploid, and 3 were near-tetraploid. One primary tumor had a diploid karyotype without numerical or structural rearrangements. The 20 cases with a karyotype in the diploid range were statistically analyzed for gain or loss of while chromosomes and for structural abnormalities of each chromosome arm. The short arm of chromosome 1 was preferentially involved in structural rearrangements, occurring in 14 cases (p less than 0.01). In 11 of these cases, the abnormality of chromosome 1 included deletion of bands 1p32 leads to 1pter, rendering the cells monosomic for this genetic material. Of the remaining three cases, one involved a reciprocal translocation of chromosomes 1p and 12q, another had insertion of genetic material at band 1p13, and the third had an extra dark band at 1p36. No other numerical or structural abnormalities occurred with sufficient frequency to reach statistical significance (p greater than 0.20). Six of the primary tumors or cell lines in the diploid range had double minute chromatin bodies, four cell lines had homogeneously staining regions, and two cell lines had either double minute chromatin bodies or homogeneously staining regions in subpopulations of cells. Hence, partial monosomy for the short arm of chromosome 1 was the most consistent cytogenetic abnormality in the human neuroblastomas studied.

The relative amounts of the collagen chains alpha 1(I), alpha 2 and alpha 1(III) in the skin of 31 patients with osteogenesis imperfecta

1. The relative amounts of type III and type I collagen, determined as the ratio of their constituent alpha 1(III) and alpha 1(I) chains, have been measured by interrupted electrophoresis of pepsin extracts of skin collagen from 31 patients with osteogenesis imperfecta of varying severity, and from six clinically unaffected family members. In 18 patients the ratio of the alpha 1(I) to alpha 2 chains of type I collagen has also been measured. 2. In the 15 patients with osteogenesis imperfecta classified as mild or the 18 with type I disease the ratio alpha 1(III)/alpha 1(I) was significantly increased (P less than 0.001) and the ratio alpha 1(I)/alpha 2 significantly decreased (P less than 0.005) compared with age-matched control subjects. 3. In three infants with lethal (type II) osteogenesis imperfecta the ratio alpha 1(III)/alpha 1(I) was normal, contrasting with the high ratio observed by others in fibroblast cultures from some apparently similar patients. 4. The ratio of alpha 1(I)/alpha 2 and of alpha 1(III)/alpha 2(I) was increased in both clinically normal parents of a child with severe disease, and in the mother of two children with osteogenesis imperfecta (one lethal and one severe) the ratio alpha 1(III)/alpha 1(I) was increased. 5. In the remaining patients with severe bone deformity (types III and IV) the relative amounts of the different collagen chains varied. 6. These data support previous suggestions that mild or type I osteogenesis imperfecta results from a generalized inability to form sufficient type I collagen, the predominant collagen of adult bone, and imply that in many cases this may result from defective production of the alpha 1(I) chain rather than of the alpha 2 chain. Some patients with severe disease demonstrate a similar defect; but in the remainder other abnormalities of collagen or connective tissue maturation are presumably involved.

Clonal characteristics of experimentally induced "atherosclerotic" lesions in the hybrid hare

The female hybrid hare (Lepus timidus x Lepus europaeus) is heterozygous for electrophoretically separable, X-linked isoenzymes of glucose-6-phosphate dehydrogenase. The isoenzymes of this animal have been used as cellular markers in the study of the clonal origins of experimentally induced atherosclerotic lesions. Aortic lesions produced in the hybrid hare by feeding cholesterol and injuring the aortic wall with a catheter have been shown to have polyclonal characteristics and in this way are fundamentally different from atherosclerotic fibrous plaques in man.