Functional characterization and in vitro screening of Fructobacillus fructosus MCC 3996 isolated from Butea monosperma flower for probiotic potential

The fructophilic bacterium Fructobacillus fructosus MCC 3996 described in the present investigation was isolated from the nectar of Butea monosperma flower and evaluated in vitro for the manifestation of probiotic features. The strain utilizes fructose faster than glucose and is capable to grow in the range of 1-35% fructose concentration (optimum 5% w/v) and thus denotes its fructophilic nature. In vitro assessments of the strain have examined for the endurance in acidic environment/gastric juice, the better auto-aggregation ability even in the presence of hydrolytic enzymes, co-aggregation with pathogenic bacteria, hydrophobicity properties and no haemolytic activity to elucidate its feasible probiotic use. The significant antagonistic activity against several detrimental bacteria, despite lacking the bacteriocin secretion, is an astonishing feature. Owing to the indigenous origin of the isolate, it could be used as a probiotic, starter culture, and/or the active ingredient of food formulation may contribute to improve the desirable fermentation, long-term storage and nutritional benefits of foods especially rich in fructose. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provided in vitro evidence that Fructobacillus fructosus MCC 3996 have endurance in acidic gastric juice, better co-aggregation, auto-aggregation properties, splendid antagonistic activities against several bacteria involved in food spoilage/human infections, pertinent antibiotic susceptibility profile and no haemolytic activity. Also, F. fructosus have the capability to survive in the appreciable amount of fructose, and this advocates that the strain could be used as starter culture and/or the active ingredient of fructose-rich foods. The current in vitro study provided a strong basis for further in vivo research to identify the health beneficial characteristics of F. fructosus and its potential could be effectively utilized as health-boosting ingredient in food and pharmaceutical industries.

Abstract P4-02-01: Analytical validation of an automated digital scoring protocol for Ki67: International multicenter collaboration study

Background/Goal: Ki67 expression has been a valuable prognostic marker in breast cancer, but has not seen broad adoption due to lack of standardization between institutions. Automation could represent a solution. Here we tested 3 automated digital image analysis (DIA) platforms including an open source platform to: (i) Investigate the reproducibility of Ki67 measurement across platforms with supervised classifiers performed by the same operator and by multiple operators. (ii) Compare accuracy of the 3 DIA platforms against outcome (prognostic potential). (iii) Assess inter-laboratory reproducibility of a calibrated DIA tool to evaluate Ki67 in breast cancer among 10 participating labs of the International Ki67 in Breast Cancer Working Group (IKWG).

Methods: The Mib-1 antibody (Dako) was used to detect Ki67 (dilution 1:100). HALO (H) (IndicaLabs), QuantCenter (QC) (3DHistech), QuPath (QP) (open-source software) digital image analysis (DIA) platforms were used to evaluate Ki67 expression. As a ground truth, we evaluated Ki67 LI with meticulous manual tissue segmentation using the Spectrum Webscope (SW) (Aperio). Calibration was performed using 30 ER+ breast cancer cases from phase 3 of the IKWG initiative where blocks were centrally cut and stained for Ki67. The inter-laboratory analysis was done with 10 participating laboratories divided into 2 groups where members within the same group were given the same set of images. The outcome cohort consisted of 149 breast cancer cases from the Yale Pathology archives in tissue microarray format. Intra-class correlation coefficient (ICC) was used to measure reproducibility with the pre-specified criterion for success being to exceed 0.80. Kaplan-Meier analysis supported with log-rank test was performed to assess prognostic potential.

Results: All 3 DIA platforms showed excellent inter-platform reproducibility (ICC: 0.933, CI: 0.879-0.966). Also, excellent reproducibility was found between all DIA platforms and the reference standard Ki67 values of SW (QP ICC: 0.970, CI: 0.936-0.986; H ICC: 0.968, CI: 0.933-0.985; QC ICC: 0.964, CI: 0.919-0.983). The intra-DIA reproducibility was also excellent for all platforms (QP ICC: 0.992, CI: 0.986-0.996; H ICC: 0.972, CI: 0.924-0.988; QC ICC: 0.978, CI: 0.932-0.991). Comparing each DIA against outcome, the hazard ratios were similar (QP=3.309, H=3.077, QC=3.731). The inter-operator reproducibility was particularly high (ICC: 0.962-0.995). As QP is open source software and also showed the lowest intra-DIA platform variability, we selected the QP platform to investigate inter-laboratory reproducibility among 10 IKWG labs. The different-section ICC across the 10 labs was 0.974 (CI: 0.954 - 0.986). The same-section ICC estimate was 0.984 (CI: 0.971-0.992) for group 1 and 0.978 (CI: 0.956-0.989) for group 2.

Conclusions: Our results showed outstanding reproducibility both within and between DIA platforms. We also found the platforms essentially indistinguishable with respect to prediction of breast cancer patient outcome. Automated Ki67 evaluation using a calibrated, open-source DIA platform (QuPath) met the pre-specified criterion of success in the multi-institutional setting. Assessment of clinical utility is planned.

Citation Format: Acs B, Leung SC, Pelekanou V, Bai Y, Martinez-Morilla S, Toki M, Chang MC, Gholap A, Jadhav A, Hugh JC, Bigras G, Laurinavicius A, Augulis R, Levenson R, Todd A, Piper T, Virk S, van der Vegt B, Hayes DF, Dowsett M, Nielsen TO, Rimm DL. Analytical validation of an automated digital scoring protocol for Ki67: International multicenter collaboration study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-02-01.

Abstract P1-03-01: An international multicenter study to evaluate reproducibility of automated scoring methods for assessment of Ki67 in breast cancer

Background: The nuclear proliferation biomarker Ki67 has multiple potential roles in breast cancer, including prognosis-based decisions, but unacceptable between-laboratory variability has limited its clinical value. The International Ki67 Working Group (IKWG) has undertaken a systematic program to determine whether Ki67 immunohistochemistry can be analytically validated and standardized across laboratories. Technological advances and broader availability of devices for automated assessment of stained slides raise the possibility that these machines may improve on reproducibility of traditional pathologist-based visual Ki67 assessment.

Aims: To characterize reproducibility of automated machine-measured Ki67 expression using slides previously analyzed in the IKWG phase 3 study that evaluated reproducibility of visual Ki67 assessment.

Methods: Two sets of 30 previously stained slides containing core-cut biopsy sections of breast tumors were circulated to 14 laboratories for scanning and automated assessment of Ki67 expression. Sites were instructed to return average and maximum percentage of tumor cells positive for Ki67 for each slide, where maximum is designed to reflect “hot spot” analysis. Two laboratories returned scores from 2 operators; not all laboratories reported values for maximum Ki67 scores. Different operators were treated as distinct laboratories in analyses. Sixteen and 10 score sets were available for average and maximum Ki67 analyses, respectively, encompassing 7 unique scanner and 10 software platforms. Pre-specified analyses included evaluation of reproducibility across all laboratories as well as within a subgroup limited to those using Aperio scanners. The primary reproducibility metric was intraclass correlation coefficient between laboratories (ICC), regardless of device platform or software.

Results: Geometric means across 30 cases for 16 operators ranged from 11.06% to 38.11% with overall mean 16.75% (95% CI:14.45-19.42) for average scores. Geometric means for 10 operators ranged from 16.44% to 68.73% with overall mean 25.16% (95% CI: 18.71-33.84) for maximum scores. ICC for automated average scores across 16 operators was 0.83 (95% CI: 0.73-0.91) and ICC for maximum scores across 10 operators was 0.63 (95% CI: 0.44-0.80) although one outlier lab dramatically affected results. For the laboratories using the Aperio platform (8 score sets), ICC for automated average scores was 0.89 (95% CI; 0.81-0.96). These results are similar to ICC of 0.87 (95%CI; 0.81-0.93) reported using these same slides in the Phase 3 visual assessment reproducibility study in which observers counted 500 cells per slide (Leung et al, NPJBrCancer, in press).

Conclusions: Between-laboratory reproducibility for automated machine assessment of average Ki67 is similar to that for pathologist-based visual assessment of Ki67. However, the observed ICC was markedly numerically lower for the maximum score method compared to the average method, suggesting that the maximum score may not be useful as a reproducible measure of proliferation. Automated average scoring methods show promise for standardization of Ki67 scoring, supporting future studies to clinically validate Ki67.

Citation Format: Rimm DL, McShane LM, Leung SCY, Bai Y, Bane AL, Bartlett JMS, Bayani J, Chang MC, Dean M, Denkert C, Enwere E, Galderisi C, Gholap A, Hugh JC, Jadhav A, Kornaga E, Laurinavicius A, Levenson R, Lima J, Miller K, Pantanowitz L, Piper T, Ruan J, Srinivasan M, Virk S, Wu Y, Yang H, Hayes DF, Nielsen TO, Dowsett M. An international multicenter study to evaluate reproducibility of automated scoring methods for assessment of Ki67 in breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-03-01.

Comparison Between Automated and Manual Sphygmomanometer for Measuring Blood Pressure in Children

Introduction: The mercury sphygmomanometer has been the gold standard used for obtaining blood pressure (BP). However, due to environmental concerns and more use of automated BP devices, an alternative to using the standard mercury sphygmomanometer to measure BP. The aim of this study is to evaluate the accuracy of the Automated (Omron) BP device against the mercury sphygmomanometer in children.Material and Methods: One hundred children were enrolled in this study. The accuracy of Omron HEM–7121 BP readings was compared with that of mercury BP device readings. Each children had four BP measurements recorded sequentially i.e. two valid systolic readings, and two valid diastolic readings.Results: BP taken with the automated device was systolic 109.77 ± 9.97 and diastolic 74.50 ± 8.32 mm Hg compared to systolic 112.68 ± 9.98 and diastolic 77.38 ± 7.91 mm Hg measured by manual mercury sphygmomanometer BP readings (p<0.001). Automated and mercury BP measurements were correlated (r = 0.89, systolic BP; r = 0.82, diastolic BP). Linear regression analysis showed that the automated systolic BP is a significant predictor (? = 0.897, p < 0.001) of manual systolic BP. Similarly, automated diastolic BP was also a significant predictor (? = 0.829, p< 0.001) of manual diastolic BP.Conclusion: This study concludes that the automated BP device is reliable and accurate for measuring the BP in children.J Nepal Paediatr Soc 2015;35(1):13-17

Sacrococcygeal Teratoma: Experience with 36 Patients in a Teritiary Care Hospital

Introduction: Sacrococcygeal teratomas (SCT) are the most common solid tumours in the neonatal period, originate from embryonic totipotent cells. Most of them are benign however some that present later in life and have major intra-pelvic component have greater malignant potential. Complete surgical excision provides an excellent prognosis. The aim of this study was to describe the clinical profile, age of presentation, sex distribution, diagnostic evaluation and management of children with a histological confirmed diagnosis of sacrococcygeal teratoma.Material and Methods: Patients with histological diagnosis of sacrococcygeal teratoma during a period from January 2011 to December 2012 were included in this retrospective study. Data collected included age of presentation, sex distribution, symptoms, associated anomalies, diagnostic evaluation, operative approach technique employed, tumour histology, operative complications and outcome.Results: Thirty six patients with diagnosis of sacrococcygeal teratoma were included in the study. Of these children, 58.33% were females and 41.66% were males. The median age at presentation was four days. 69.44% of patients presented during the neonatal period. 77.77% of patients presented with sacrococcygeal mass followed by lower abdominal mass in 11.11%. The tumour was resected by sacral approach in 27 patients and abdomino sacral approach in nine patients. Tumour was resectable in 34 patients and two had incomplete resection. Follow up duration varied from six months to 24 months.Conclusion: Sacrococcygeal teratomas represent a group of benign and malignant lesions of children. Neonates present with benign disease and aggressive lesions are seen as age progresses. Overall survival of SCT is high.J Nepal Paediatr Soc 2015;35(1):89-93

New enterant in the class of uropathogens-Shewanella algae

A 70 year old diabetic male presented with fever, urgency of micturition, oliguria, swelling over both legs. His midstream urine sample was sent for microbiological examination and it revealed Shewanella algae. Patient was treated with antibiotics and he recovered completely after treatment.DOI: http://dx.doi.org/10.3126/ajms.v6i4.11503 Asian Journal of Medical Sciences Vol.6(4) 2015 92-95

Reconstruction of complex soft-tissue defects around the knee joint with distally based split vastus lateralis musculocutaneous flap: a new technique

AIMS

The aim of this study was to report our experience of using distally based spilt vastus lateralis musculocutaneous flaps for soft-tissue defects around the knee joint - a new technique.

MATERIAL AND METHODS

Cadaver dissection studies were conducted in three cadavers to demonstrate perforators entering the lower third of the vastus lateralis muscle arising from the superior lateral genicular artery. Its application in eight clinical cases for the reconstruction of soft-tissue defects around the knee joint is reported.

RESULTS

Seven out of eight flaps survived well without any flap loss. One flap with a skin island measuring 12 × 20 cm suffered a loss of 2 cm distally. This was later treated with skin grafting. Six out of eight donor sites were closed primarily. Six patients achieved full functional range of motion by 3 months. One patient had a 10° limitation of knee extension. One patient had foot drop due to primary injury and walks with a limping gait.

CONCLUSIONS

This flap is a new reconstructive option for knee defects. It can reach distally up to the tibial tuberosity and does not require an intraoperative change of position. The donor site can be closed primarily and is hidden inside the clothing. The function of the knee is not affected as the majority of the muscle is kept in continuity.

Hemin therapy suppresses inflammation and retroperitoneal adipocyte hypertrophy to improve glucose metabolism in obese rats co-morbid with insulin-resistant type-2 diabetes

AIM

Visceral adiposity and impaired glucose metabolism are common patho-physiological features in patients co-morbid with obesity and type-2 diabetes. We investigated the effects of the heme-oxygenase (HO) inducer hemin and the HO blocker stannous-mesoporphyrin (SnMP) on glucose metabolism, adipocyte hypertrophy and pro-inflammatory cytokines/mediators in Zucker diabetic fatty (ZDF) rats, a model characterized by obesity and type-2 diabetes.

METHODS

Histological, morphological/morphometrical, Western immunoblotting, enzyme immunoassay, ELISA and spectrophotometric analysis were used.

RESULTS

Treatment with hemin enhanced HO-1, HO activity and cGMP, but suppressed retroperitoneal adiposity and abated the elevated levels of macrophage-chemoattractant protein-1 (MCP-1), ICAM-1, tumour necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), IL-1β, NF-κB, c-Jun-NH2-terminal-kinase (JNK) and activating-protein (AP-1), with parallel reduction of adipocyte hypertrophy. Correspondingly, important proteins of lipid metabolism and insulin-signalling such as lipoprotein lipase (LPL), insulin-receptor substrate-1 (IRS-1), GLUT4, PKB/Akt, adiponectin, the insulin-sensitizing and anti-inflammatory protein and adenosine-monophosphate-activated protein kinase (AMPK) were significantly enhanced in hemin-treated ZDF rats.

CONCLUSION

Elevated retroperitoneal adiposity and the high levels of MCP-1, ICAM-1, TNF-α, IL-6, IL-1β, NF-κB, JNK and AP-1 in untreated ZDF are patho-physiological factors that exacerbate inflammatory insults, aggravate adipocyte hypertrophy, with corresponding reduction of adiponectin and deregulation of insulin-signalling and lipid metabolism. Therefore, the suppression of MCP-1, ICAM-1, TNF-α, IL-6, IL-1β, NF-κB, JNK, AP-1 and adipocyte hypertrophy, with the associated enhancement of LPL, adiponectin, AMPK, IRS-1, GLUT4, PKB/Akt and cGMP in hemin-treated ZDF are among the multifaceted mechanisms by which the HO system combats inflammation to potentiate insulin signalling and improve glucose and lipid metabolism. Thus, HO inducers may be explored in the search of novel remedies against the co-morbidities of obesity, dysfunctional lipid metabolism and impaired glucose metabolism.

12-lipoxygenase activity plays an important role in PAR4 and GPVI-mediated platelet reactivity

Following initial platelet activation, arachidonic acid is metabolised by cyclooxygenase-1 and 12-lipoxygenase (12-LOX). While the role of 12-LOX in the platelet is not well defined, recent evidence suggests that it may be important for regulation of platelet activity and is agonist-specific in the manner in which it regulates platelet function. Using small molecule inhibitors selective for 12-LOX and 12-LOX-deficient mice, the role of 12-LOX in regulation of human platelet activation and thrombosis was investigated. Pharmacologically inhibiting 12-LOX resulted in attenuation of platelet aggregation, selective inhibition of dense versus alpha granule secretion, and inhibition of platelet adhesion under flow for PAR4 and collagen. Additionally, 12-LOX-deficient mice showed attenuated integrin activity to PAR4-AP and convulxin compared to wild-type mice. Finally, platelet activation by PARs was shown to be differentially dependent on COX-1 and 12-LOX with PAR1 relying on COX-1 oxidation of arachidonic acid while PAR4 being more dependent on 12-LOX for normal platelet function. These studies demonstrate an important role for 12-LOX in regulating platelet activation and thrombosis. Furthermore, the data presented here provide a basis for potentially targeting 12-LOX as a means to attenuate unwanted platelet activation and clot formation.

Oxadiazole 2-oxides are toxic to the human hookworm, Ancylostoma ceylanicum, however glutathione reductase is not the primary target

Hookworm disease, characterized by severe anemia and cognitive and growth delays, currently affects an estimated 740 million people worldwide. Despite the prevalence of this parasitic disease, few effective drug therapies are in use today, and the heavy reliance upon benzimidazoles highlights the need for the development of novel chemotherapies. Recent work with the trematode parasite Schistosoma mansoni has identified oxadiazole 2-oxides as effective antischistosomal compounds that function by targeting and inhibiting the antioxidant enzyme, thioredoxin glutathione reductase. In this study, a related enzyme, glutathione reductase, from the human hookworm Ancylostoma ceylanicum was identified and characterized, and its in vitro activity in the presence of the oxadiazole 2-oxides was analyzed. Ex vivo worm killing assays were also conducted to establish the relationship between a given compound's effect upon worm survival and inhibition of recombinant glutathione reductase (rAceGR). Finally, the in vivo anthelminthic efficacy of furoxan (Fx) was assessed in the hamster model of hookworm infection. The predicted amino acid sequence of AceGR contained a prototypical glutathione reductase active site sequence, but no thioredoxin reductase consensus sequences, suggesting that the glutathione and thioredoxin pathways of A. ceylanicum are distinct. Although ten of the forty-two oxadiazole 2-oxides tested inhibited rAceGR activity by at least fifty percent, and fifteen compounds were toxic to parasites ex vivo, little overlap existed between these two results. We therefore suggest that AceGR is not the primary target of the oxadiazole 2-oxides in effecting parasite death. Lastly, oral treatment of A. ceylanicuminfected hamsters with furoxan resulted in significantly improved weight gains and reduced intestinal worm burdens compared to vehicle treated controls, supporting continued development of this molecule as a novel anthelminthic.

Rod diameter prediction in patients with osteogenesis imperfecta undergoing primary osteotomy

SUMMARY

Because the cross-sectional shape of the long bones of patients with osteogenesis imperfecta is often elliptical, the use of preoperative radiographs to determine intramedullary rod diameter in these patients undergoing osteotomy may be misleading. To investigate this, the authors correlated the narrowest inner bone diameter (NID) on preoperative radiographs to the rod diameter (RD) on postoperative radiographs. The authors evaluated 79 bones in 27 patients undergoing primary osteotomy with intramedullary fixation. Only 5% of the bones had an equal NID and RD, with 81% of bones having a smaller RD than the measured NID. Although a positive correlation was found between RD and NID (correlation coefficient 0.76), measurement of the NID on preoperative radiographs did not provide a good prediction of the actual RD used in this series of children with osteogenesis imperfecta.

Diet-induced change in fatty acid composition of plasma triacylglycerols is not associated with change in glucagon-like peptide 1 or insulin sensitivity in people with type 2 diabetes

BACKGROUND

Polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs) have been shown to positively affect blood lipids; however, their comparative effects on insulin sensitivity are unclear.

OBJECTIVE

Our objective was to investigate whether chronic intake of MUFAs or PUFAs improves insulin sensitivity in people with type 2 diabetes via stimulation of the endogenous gut hormone glucagon-like peptide 1 [7-36] amide (GLP-1).

DESIGN

Nine overweight people with type 2 diabetes received isoenergetic high-MUFA (20.3 +/- 3.5% of total energy) or high-PUFA (13.4 +/- 1. 3%) diets for 24 d in a randomized, double-blind crossover design.

RESULTS

Weight and glycemic control remained stable throughout the study. Despite a significant change in the plasma triacylglycerol linoleic-oleic acid ratio (L:O) with both diets (MUFA: from 0.46 +/- 0.03 to 0.29 +/- 0.02, P: < 0.005; PUFA: from 0.36 +/- 0.04 to 0.56 +/- 0.05, P: < 0.05) and the phospholipid L:O (1.7 +/- 0.1 to 2.0 +/- 0.3; P: = 0.04) during consumption of the PUFA diet, this change was not associated with a change in insulin sensitivity, measured by the short-insulin-tolerance test. There was a significant reduction in the ratio of total to HDL cholesterol during consumption of the PUFA diet (5.2 +/- 0.4 compared with 4.7 +/- 0.3; P: = 0.005) but no change with the MUFA diet. There was no change in the fasting or postprandial incremental area under the curve in response to an identical standard test meal for glucose, insulin, triacylglycerol, nonesterified fatty acids, or GLP-1.

CONCLUSIONS

Over the 3-wk intervention period, diet-induced change in the triacylglycerol or phospholipid L:O was not associated with either increased stimulation of GLP-1 or a change in insulin sensitivity in people with type 2 diabetes.

Accessory soleus muscle as a cause of resistance to correction in congenital club foot: a case report

A 14-month-old female with bilateral clubfeet was initially treated by serial casting and percutaneous tenotomy of the Achilles tendon, bilaterally. Both clubfeet subsequently underwent surgical treatment with a posteromedial release through a Cincinnati incision. At surgery on one clubfoot, an accessory Soleus muscle was found anterior to the Achilles tendon with a distinct insertion on the upper surface of calcaneus, anterior and medial to the insertion of Achilles tendon. This accessory Soleus muscle may have been the cause of resistance to correction in this congenital clubfoot.

HMG-CoA reductase is not the site of the primary defect in phytosterolemia

Phytosterolemia is an autosomal recessive disorder characterized by the excessive absorption, reduced excretion, and consequent high tissue and plasma levels of plant sterols, by the presence of tendon xanthomas, and by premature atherosclerosis. Low HMG-CoA reductase (HRase) activity and mass have been reported in liver and mononuclear leucocytes and low mRNA levels in liver from phytosterolemic subjects. These results led to the proposal that the primary defect in this condition involves the HRase gene locus. We examined this hypothesis in phytosterolemic subjects and heterozygous parents from four unrelated families. A variable number tandem repeat (VNTR) polymorphism of the HRase gene in the three informative families and a ScrFI restriction fragment length polymorphism (RFLP) within intron 2 of the gene in one of these families, segregated independently of the disease phenotype. Biological parentage was confirmed in the family in whom both polymorphisms failed to segregate with the disorder. These results conclusively exclude the HRase gene locus as the site of the primary defect in phytosterolemia. The study was extended by examining plasma levels of mevalonic acid and lathosterol, both markers of cholesterol biosynthesis, in response to cholestyramine, a bile acid sequestrant that is known to up-regulate HRase. Oral administration of cholestyramine resulted in a substantial (7.7-fold) increase in mevaIonic acid levels in two phytosterolemic subjects, compared with a 2.2-fold rise in their obligate heterozygote parents and a 2.3-fold increase in three healthy control subjects. The lathosterol/cholesterol (L/C) ratio showed a quantitatively similar response. Baseline levels of mevalonate and the L/C ratio were low in the phytosterolemic patients in conformity with reports of reduced cholesterol biosynthesis and HRase activity in this disorder. These functional data provide support for the concept that the primary defect in phytosterolemia does not affect a trans gene locus responsible for the constitutive expression or regulation of HMG-CoA reductase.

Behavior of human apolipoprotein A-I: phospholipid and apoHDL:phospholipid complexes in vitro and after injection into rabbits

Apolipoprotein A-I was purified from human high density lipoprotein and complexed with polyunsaturated phosphatidylcholine (PC) in deoxycholate (Lipostabil); the bile salt was removed subsequently by dialysis. The behavior of the resultant apoA-I/PC complexes was compared with that of Lipostabil in vitro and after injection into rabbits. In vivo apoA-I/PC complexes had the density of HDL throughout but had both alpha and pre beta electrophoretic mobility, the latter probably reflecting dissociation of apoA-I from PC. Lipostabil initially behaved like LDL but gradually acquired the density of HDL after incubation with plasma and in vivo. Both preparations increased plasma total phospholipids in normolipidemic rabbits to a similar extent, but, increments in HDL phospholipid were greater after apoA-I/PC complexes were injected. ApoHDL/PC complexes, prepared in a similar manner, appeared to promote efflux of cholesterol from perfused rabbit aortas in the presence of lecithin:cholesterol acyltransferase (LCAT) activity, consistent with a stimulatory effect on cholesterol mobilization. Injection of apoHDL/PC complexes into hyperlipidemic rabbits decreased plasma cholesterol but increased HDL cholesterol, whereas Lipostabil decreased both. These findings suggest that human apoA-I/PC complexes resemble HDL in their behavior more closely than does Lipostabil, and show that both types of liposome undergo modification upon interaction with plasma. It remains to be shown whether they possess any therapeutic potential.

Plasma exchange and low density lipoprotein apheresis in Watanabe heritable hyperlipidemic rabbits

Comparison of the effects of plasma exchange using lipoprotein-deficient plasma with those of LDL apheresis using a dextran sulphate column was undertaken in two groups of Watanabe heritable hyperlipidemic rabbits pre-labelled with 3H-cholesterol. Total and HDL cholesterol were reduced more by plasma exchange but HDL cholesterol rebounded higher after LDL apheresis; rises in HDL cholesterol correlated with preceding decreases in both HDL and total cholesterol. An increase in the specific activity of HDL cholesterol occurred on the day after each procedure, being more marked after plasma exchange, and was accompanied by a decrease in the cholesterol/phospholipid ratio of HDL. These results suggest that an influx of extravascular HDL into plasma occurred after both procedures, resulting in mobilization of tissue cholesterol.

Failure of experimental atherosclerosis to sensitize coronary arteries to spasm in hypercholesterolemic rabbits

Since hypercholesterolemia sensitizes isolated rabbit coronary arteries to vasoconstrictor stimuli, we assessed the possibility of reproducing occlusive coronary spasm both in vitro and in vivo in atherosclerotic rabbits. In Langendorff-perfused hearts from nine atherosclerotic rabbits (2% cholesterol diet for 18 weeks), despite a threefold increase of cholesterol concentration in the coronary wall compared with nine control rabbits, ergonovine and serotonin did not produce any increase of coronary vascular resistances; the increase produced by pitressin was significantly less in atherosclerotic than in normal hearts (56 +/- 13% vs 138 +/- 28%, p less than 0.05, respectively), whereas that produced by phenylephrine was similar (10.1 +/- 1.8% vs 8.5 +/- 2.4%, p = n.s.). In eight other unanesthetized rabbits we recorded the ECG during ergonovine administration (0.05 mg/kg) and during hypothalamic stimulation before and at regular intervals during the 2% cholesterol diet; rabbits survived for periods ranging from 1 to 22 weeks (mean 9.6 weeks). Only one animal had ST depression during episodes of marked tachycardia; no ischemic ECG changes were ever observed in the other rabbits despite the diffuse subintimal coronary deposition of cholesterol found postmortem. Thus, in atherosclerotic rabbits with chronic marked hypercholesterolemia, coronary arteries do not develop occlusive coronary spasm as observed in patients with variant angina.

Superiority of partial ileal bypass over cholestyramine reducing cholesterol in familial hypercholesterolaemia

Low density lipoprotein (LDL) turnover studies were conducted on three occasions in each of six patients with heterozygous familial hypercholesterolaemia (FH)-on diet, after 1 month on cholestyramine 16 g/day, and 2 months after partial ileal bypass. Partial ileal bypass lowered total and LDL cholesterol levels and increased the fractional catabolic rate of LDL to a greater extent than did cholestyramine; this difference presumably reflects the greater increase in bile acid excretion induced by the surgical procedure. Studies in two other heterozygotes showed that partial ileal bypass specifically enhanced receptor-mediated catabolism of LDL. The findings support the concept that therapeutic stimulation of bile acid synthesis increases the rate of receptor-mediated uptake and degradation of LDL by the liver.

Defects of receptor-mediated low density lipoprotein catabolism in homozygous familial hypercholesterolemia and hypothyroidism in vivo

The role of low density lipoprotein (LDL) receptors in the pathogenesis of hereditary and acquired forms of hypercholesterolemia has been investigated in vivo by simultaneously determining total and receptor-independent LDL catabolism with 125I-labeled LDL and 131I-labeled LDL coupled with cyclohexanedione. Receptor-mediated catabolism of LDL, determined as the difference between the turnover of 125I and 131I, was found to be virtually absent in two homozygotes with familial hypercholesterolemia and markedly reduced in a hypothyroid patient. Treatment of the latter with L-thyroxine markedly stimulated receptor-mediated catabolism and reduced LDL levels as did cholestyramine administration in a control subject. Reduction of LDL levels by plasma exchange in a control subject and homozygote had no such effect. These results demonstrate the existence of an intrinsic and almost total defect of receptor-mediated LDL catabolism in homozygous familial hypercholesterolemia and demontrate an analogous but reversible abnormality in hypothyroidism.

Effects of intravenous phospholipid on low density lipoprotein turnover in man

The mechanism of the rise in plasma low density lipoprotein (LDL) levels following intravenous administration of a triglyceride-phospholipid emulsion (Intralipid) has been investigated by measuring LDL turnover in eight healthy subjects. The plasma half-life, and the absolute and fractional catabolic rates of LDL protein (apo-LDL) were unaffected by intragastric Intralipid, whereas apo-LDL half-life was prolonged and its fractional catabolic rate was decreased by intravenous Intralipid. Similar changes were observed after intravenous administration of the egg phospholipid constituent of Intralipid. Accompanying increases in the oleate: linoleate ratio of both high and low density lipoprotein cholesterol esters were secondary to phospholipid exchange between infused and endogenous lecithin. These results suggest that the increased concentration of LDL in plasma following intravenous administration of egg phospholipid-containing emulsions was due, at least in part, to a decrease in the fractional catabolic rate of apo-LDL. The data further suggest a possible relationship between apo-LDL catabolism and the fatty acid composition of LDL.