Liposome-delivered angiostatin strongly inhibits tumor growth and metastatization in a transgenic model of spontaneous breast cancer

The possibility to inhibit tumor growth by interfering with the formation of new vessels, which most neoplasias depend on, has recently raised considerable interest. An angiogenic switch, in which proliferating cells acquire the ability to direct new vessel formation, is thought to be an early step in the natural history of solid tumors. Using a transgenic model of breast cancer, which shows many similarities to its human counterpart, including ability to metastasize, we targeted angiostatin production to an early stage of tumor formation. Liposome-delivered angiostatin considerably delayed primary tumor growth and, more importantly, inhibited the appearance of lung metastases. These findings can be relevant to the design of therapeutic intervention in humans.

[Percutaneous or surgical trachetomy. Prospective, randomized comparison of the incidence of early and late complications]

BACKGROUND

To compare early and late complications after either conventional surgical or percutaneous dilatational tracheostomy.

DESIGN

Prospective, randomized study.

SETTING

General intensive care unit and neuro-surgical intensive care unit in a university hospital.

PATIENTS

50 consecutive patients, requiring tracheostomy for prolonged mechanical ventilation.

INTERVENTIONS AND MEASUREMENTS

Patients were randomly allocated to receive either surgical (surgical group, n = 25) or percutaneous dilatational tracheostomy (percutaneous group, n = 25). Occurrence of perioperative complication were carefully evaluated during ICU stay. Late complications were evaluated with both physical and endoscopic examination at 1, 3 to 6 months after tracheostomy.

RESULTS

All surgical and percutaneous tracheostomies were successfully completed and no deaths directly related to the tracheostomy procedures were reported. Completion of the procedure required 41 +/- 14 min in the surgical group and 14 +/- 6 min in the percutaneous one (p < 0.0001). The incidence of early perioperative complications was higher in the surgical group (36%) than in percutaneous one (12%), (p < 0.05). The endoscopic follow-up demonstrated one segmental malacia and one stenosis of the trachea in the percutaneous group only (p = n.s.). Skin repair was better after percutaneous tracheostomy than in the surgical group (p < 0.01).

CONCLUSIONS

In experienced hands, percutaneous dilatational tracheostomy is as safe and effective as the conventional surgical tracheostomy. The percutaneous technique is less time-consuming and has a lower rate of early infectious complications with better cosmetic results than the surgical technique.

Transgenic mice expressing a human apolipoprotein[a] allele

The most important determinant of plasma levels of Lp[a] are sequence differences at the highly polymorphic apolipoprotein[a] (apo[a]) locus. To define the sequences that mediate the regulation of apo[a] expression, we cloned a 370 kb DNA fragment that included a 130 kb apo[a] gene, and 40 kb 5'- and 200 kb 3'-flanking region from an individual with high plasma levels of Lp[a] using a YAC vector. This genomic clone was used to generate transgenic mice. In the YAC-apo[a] transgenic mouse, apo[a] was only expressed in the liver, as it is in humans. The mean serum level of apo[a] in 4-week-old YAC-apo[a] transgenic mice was 20 mg/dl. In the female mice the levels of apo[a] varied over a 1.5-fold range during the 4-day estrus cycle and the levels correlated directly with serum progesterone levels. The serum levels of apo[a] decreased to almost undetectable level in male mice after puberty and this decrease was reversed by castration. Ingestion of a high-fat diet resulted in a approximately 100-fold fall in hepatic apo[a] mRNA levels and >60-fold decrease in serum apo[a] levels. To delimit the control elements that mediate tissue-specific and sex hormone-responsive apo[a] transcription, we derived a reporter YAC in which 40 kb of 5' flanking sequences from the cloned apo[a] allele were linked to a luciferase reporter gene. Analysis of four independent transgenic lines revealed no hepatic luciferase expression, suggesting that important cis -acting elements located outside the apo[a] 5'-flanking region are necessary for in vivo expression of apo[a].

Increased cholesterol efflux potential of sera from ApoA-IMilano carriers and transgenic mice

The ability of HDL to remove cholesterol from peripheral cells and drive it to the liver for excretion is believed to explain most of the strong inverse correlation between plasma HDL cholesterol levels and coronary heart disease. Carriers of the ApoA-IMilano (A-IM) mutant have a severe hypoalphalipoproteinemia but are not at increased risk for premature of coronary heart disease. To explain this apparent paradox, we compared the capacity of serum from A-IM and control subjects to extract cholesterol from Fu5AH cells. Because the A-IM carriers are all heterozygotes for the mutation, we also compared the cholesterol efflux capacity of serum from transgenic mice expressing A-IM or wild-type ApoA-I (A-IWT), in the absence of murine ApoA-I. In the whole series of human or mouse sera, cholesterol efflux was significantly correlated with several HDL-related parameters; after adjustment for concomitant variables, the only parameter that remained significantly correlated with cholesterol efflux was the serum ApoA-I concentration (r2=0.85 in humans and 0.84 in mice). The same was true when samples from control subjects, A-IM carriers, A-IWT or A-IM mice were analyzed separately. Cholesterol efflux to sera from the A-IM carriers was only reduced slightly compared with control sera (25.0+/-4.2% versus 30.4+/-3.3%), although there was a large reduction (-45%) in the serum ApoA-I concentration in the former. Cholesterol efflux was also lower to sera from A-IM than A-IWT mice (15.6+/-3.8% versus 30. 1+/-7.1%), but less than expected from the 70% reduction in serum ApoA-I concentration. A relative efflux potential of serum was calculated in each group as the slope of the regression line fitting cholesterol efflux to ApoA-I concentrations. Therefore, the relative efflux potential reflects the relative efficiency of ApoA-I in determining cell cholesterol efflux. The relative efflux potential of mouse and human sera was in the following order: A-IM mice>A-IM carriers>A-IWT mice=control subjects, suggesting a gene-dosage effect of the A-IM mutation on the efficiency of serum to extract cholesterol from cells. The high efficiency of A-IM-containing HDL for cell cholesterol uptake would result in an improved reverse cholesterol transport in the A-IM carriers, possibly explaining the low susceptibility to atherosclerosis development.

Improvement of pulmonary function after lobectomy for non-small cell lung cancer in emphysematous patients

OBJECTIVE

Pulmonary emphysema is frequently associated with lung cancer and, because of the impaired pulmonary function involved, it may contraindicate surgical treatment. However, improvement of pulmonary function has been observed after surgical resection in patients with advanced emphysema. The aim of this study was to evaluate whether pulmonary emphysema, as assessed by pulmonary function tests and radiological evaluation, can influence postoperative respiratory function after lobectomy for non-small cell lung cancer (NSCLC).

METHODS

Respiratory function was evaluated before and after lobectomy for NSCLC. Radiological evaluation of emphysema was performed on chest X-ray and CT scan. Patients that had undergone chemo- or radiotherapy or had segmental or lobar atelectasis were excluded from the study.

RESULTS

Thirty-five patients entered the study. A decrease in static lung volumes was observed after surgery. Total lung capacity (TLC) decreased from 6.58+/-0.92 to 5.46+/-0.77 l; functional residual capacity (FRC) from 3.70+/-0.88 to 2.96+/-0.73 1 and residual volume (RV) from 2.93+/-0.78 to 2.2+/-0.53 l. However, in a subgroup of 10 patients (Group 1), dynamic volumes after surgery were unchanged or slightly increased (forced vital capacity (FVC) from 3.23+/-0.65 to 3.3+/-0.68 l; forced expiratory volume in 1 s (FEV1) from 2.14+/-0.51 to 2.25+/-0.54 l), and airway resistances (sRaw) decreased from 15.58+/-5.18 to 11.42+/-5.25 cm H2O/s. Preoperative data showed that these patients had a greater obstruction, with FEV1 changing from 69+/-12.42 to 72.70+/-13.72% of predicted, as compared with a change from 87+/-12.7 to 72.08+/-13.10% in the other group of 25 patients (Group 2). Correlation analysis reached statistical significance between FEV1% variation (deltaFEV1%) and preoperative FEV1 and FVC% (r = -0.49, P = 0.002 and r = -0.5, P = 0.001, respectively) and between delta (FEV1)% and radiological scores for 3-level CT (r = 0.39, P = 0.04) and the sum of chest X-ray, single and 3-level CT scores (r = 0.49, P = 0.01).

CONCLUSIONS

Pulmonary function may remain unchanged or even increase after lobectomy in patients with a pronounced emphysematous component of airway obstruction. The identification of preoperative parameters that identify this group of patients could extend the indications for the treatment of lung cancer in patients with pulmonary emphysema.

Human apolipoproteins A-I and A-II in cell cholesterol efflux: studies with transgenic mice

The first step in reverse cholesterol transport is the movement of cholesterol out of cells onto lipoprotein acceptors in the interstitial fluid. The contribution of specific lipoprotein components to this process remains to be established. In this study, the role of human apolipoproteins (apo) A-I and A-II in the efflux of cellular cholesterol was investigated in transgenic mouse models in which the expression of murine apoA-I was abolished due to gene targeting (A-IKO). Serum from A-IKO mice and from mice expressing human apoA-I and/or human apoA-II was incubated with [3H]cholesterol-labeled Fu5AH rat hepatoma cells for 4 hours at 37 degrees C. The cholesterol efflux to the serum of A-IKO mice was markedly lower than that to the serum of mice transgenic for human apoA-I (5.0 +/- 1.5% versus 25.0 +/- 4.0%). Expression of human apoA-II alone did not modify the cholesterol efflux capacity of A-IKO mouse serum. Cholesterol efflux to serum of mice expressing human apoA-II together with human apoA-I was significantly lower than that to human apoA-I mouse serum (20.0 +/- 2.3% versus 25.0 +/- 4.0%). Regression analysis of cholesterol efflux versus the lipid/apolipoprotein concentrations of mouse serum suggested that 3 independent factors contribute to determine the cholesterol efflux potential of serum: the apolipoprotein composition of HDL, the serum concentration of HDL phospholipids, and the presence of a small fraction of particles containing apoA-I.

Surgical treatment of non-small cell lung cancer in patients 70 years of age or older

BACKGROUND

Indications to surgical treatment of lung cancer in the elderly are still being discussed. The aim of this study was to evaluate postoperative complications and survival after surgery for non-small cell lung cancer (NSCLC) in patients 70 years of age or older.

METHODS

During a 4 year and 6 month period, 76 patients (67 men and 9 women) entered the study.

RESULTS

Postoperative complications occurred in 15 cases (19.7%) and the 30-day operative mortality was 1.3%. The overall 54 month actuarial survival was 53%. Mortality at 12 months wasn't related to stage of disease, histology or lobectomy versus wedge resection but was higher in those patients who had had postoperative cardiopulmonary complications. Results of preoperative spirometry, blood gas and cardiac status were predictive of mortality at twelve months (p < 0.05).

CONCLUSIONS

Surgery for NSCLC in the elderly should not be denied on the basis of age alone. Postoperative outcome is mainly related to concomitant cardiopulmonary disease.

Elevated triglycerides and low HDL cholesterol in transgenic mice expressing human apolipoprotein A-I(Milano)

In general, plasma concentrations of high density lipoproteins (HDL) are inversely related to the incidence of coronary artery disease. One exception to this trend is individuals with apolipoprotein A-I(Milano) (apo A-IM), a molecular variant of apo A-I, which results in very low plasma apo A-I and HDL-cholesterol levels. Despite these low levels, and other lipoprotein defects, individuals with this mutation have no increased risk for cardiovascular disease. As a first step in proving why apo A-IM carriers appear to be protected from the pro-atherogenic effect of a low HDL, transgenic mice expressing apo A-IM were generated. Mice expressing either wild-type human apo A-I or apo A-IM, together with human apo A-II, were crossed into mice lacking murine apo A-I. Apo A-IM/A-II mice had lower cholesterol and HDL plasma levels compared to apo A-I/A-II mice. Moreover, as in human carriers, apo A-IM mice were characterized by elevated triglyceride plasma levels and by the presence of a population of very small HDL particles. These results indicate that the expression of apo A-IM in a mouse model reproduces the major lipid/lipoprotein abnormalities observed in human carriers. Thus, apo A-IM transgenic mice appear to be a suitable model in which to assess whether the mutation has an anti-atherogenic effect.

A transgenic mouse model for the detection of cellular stress induced by toxic inorganic compounds

Transgenic mice for genotoxicity testing have been developed, although no such models have been produced for the evaluation of toxic, nongenotoxic chemical compounds. We have developed a transgenic mouse model for the analysis of toxic inorganic compounds. We engineered a mouse lineage with the human growth hormone (hGH) gene under the control of the human hsp70 promoter, in which a plasma-detectable hGH response can be elicited by exposure to heat shock. In primary cell cultures from these mice, hGH release was observed following treatment with several toxic inorganics. Transgenic mice injected intraperitoneally with sodium arsenite, cadmium chloride, copper sulphate, or methylmercurium chloride showed significant hGH levels in plasma.

High density lipoprotein particle size restriction in apolipoprotein A-I(Milano) transgenic mice

Human carriers of apolipoprotein A-I(Milano) (Arg173 --> Cys substitution in apolipoprotein A-I) are characterized by an HDL deficiency in which small, dense HDL accumulate in plasma. Because affected individuals are heterozygous for this mutation, the full impact of apolipoprotein A-I(Milano) (apoA-I(Milano)) on HDL-cholesterol metabolism is unknown. In this study, apoA-I(Milano) transgenic mice were used to evaluate the extent of apoA-I(Milano) dimerization and HDL particle size restriction in the absence of wild-type apoA-I. Murine apoA-I knockout mice were utilized to express apoA-I(Milano) and human apoA-II in the presence of wild-type, human apoA-I (apoA-IMilano/A-Iwt/A-II) and in its absence (apoA-IMilano/A-II). Plasma HDL-cholesterol concentrations were similar (30 mg/dl) in both lines of apoA-I(Milano) transgenic mice. In the apoA-IMilano/A-Iwt/A-II phenotype, 14% of the apoA-I(Milano) formed homodimers and 33% formed heterodimers with apoA-II. ApoA-I(Milano) homodimers increased by 71% in the apoA-IMilano/A-II transgenics and was associated with an abundance of small, 7.6-nm HDL3-sized particles compared to the 9.5, 8.3, and 7.6-nm-sized particles in apoA-IMilano/A-Iwt/A-II mice. The unesterified cholesterol/cholesteryl ester mole ratio of HDL was elevated by 45% in apoA-IMilano/A-Iwt/A-II mice and by 90% in apoA-IMilano/A-II transgenics compared to wild-type (human apoA-I/A-II). Both apoA-I(Milano) transgenics possessed normal levels of plasma LCAT activity, but endogenous cholesterol esterification rates were reduced by 50% compared to controls. Thus, HDL particle size restriction was not the result of impaired LCAT activation; rather, dimerization of apoA-I(Milano) limited the esterification of cholesterol on endogenous HDL. In the absence of wild-type apoA-I, the more extensive dimerization of apoA-I(Milano) severely limited cholesteryl ester accumulation on plasma HDL accounting for the abundance of small, 7.6-nm HDL3 particles in apoA-IMilano/A-II mice.

Imaging of bronchial carcinoid tumors associated to Cushing syndrome with 111In-Octreoscan scintigraphy and immunoscintigraphy with anti-chromogranin monoclonal antibodies. Report of two cases

Bronchial carcinoid tumors are neuroendocrine neoplasms capable of expressing somatostatin receptors and of secreting neuromediators such as ACTH and chromogranins. Radiologic appearance is usually non-specific and has to be distinguished from benign pulmonary nodules and other malignant diseases. Standard radiological techniques have limited accuracy in the evaluation of such lesions. Radioisotopic imaging techniques may increase the specificity of diagnostic assessment. The role of immunoscintigraphy with anti-chromogranin A and B monoclonal antibodies (MoAbs) and of 111In-Octreoscan scintigraphy is evaluated in two cases of bronchial carcinoid tumors associated to Cushing syndrome.

Temporary main bronchial occlusion under bronchoscopic control in the evaluation of candidates for pneumonectomy

BACKGROUND

In this study we report our experience with temporary main bronchial occlusion in the preoperative evaluation of candidates for pneumonectomy.

METHODS

Between January 1991 and January 1994, 57 candidates for pneumonectomy underwent a 15-minute temporary main bronchial occlusion with an inflatable balloon during fiberoptic bronchoscopy. The following parameters were monitored during bronchial occlusion: general status, ECG, arterial pressure, heart rate and respiratory rate. Arterial blood gases were measured after 7 and 14 minutes. Values at 7 and at 14 minutes were compared with those obtained before the procedure. Patients were considered suitable surgical candidates for pneumonectomy if PaCO2 < 42 mmHg and pH > 7.35.

RESULTS

Fifty-three patients were considered functionally operable. Three patients were considered functionally inoperable (PaCO2 > 42 mmHg, pH < 7.35 and appearance of dyspnea). One patient was excluded from the analysis because of balloon mispositioning due to a coughing fit. Sixteen of the operable patients underwent pneumonectomy and all did well without clinical evidence of respiratory insufficiency. At present 11 patients are alive, all without chronic respiratory insufficiency (mean follow-up 14 months). No postoperative mortality related to cardiorespiratory problems was observed.

CONCLUSIONS

Temporary main bronchial occlusion is a simple and inexpensive test that can correctly predict functional resectability in candidates for pneumonectomy.

Efficacy of ketorolac tromethamine and extrapleural intercostal nerve block on post-thoracotomy pain. A prospective, randomized study

BACKGROUND

Post-thoracotomy pain causes severe impairment of the respiratory function. Epidural analgesia is effective in the treatment of post-thoracotomy pain but may give rise to significant side-effects. Other low-risk and cost-effective analgesic treatments are therefore required.

METHODS

Thirty male patients who had undergone pulmonary lobectomy entered a prospective, randomized trial to evaluate the efficacy of ketorolac tromethamine (Group 2) and extrapleural intercostal nerve block (Group 3) with intermittent low-dose bupivacaine. Objective and subjective assessment was carried out at 8, 16, 24 and 48 hours postoperatively.

RESULTS

There were no significant differences between Groups 1 (control group) and 2. Vital capacity was significantly lower in Group 3 (p<0.05) than in Group 1 after 16 hours. Forced Vital Capacity was significantly higher in Group 2 than in Group 3 after 16 and 24 hours (p<0.05). Peak expiratory flow was also significantly better in Group 2 than in Group 3 after 16 hours (p<0.05). On-demand opioid consumption was significantly lower in Group 2 (p<0.001) and Group 3 (p<0.05). No side-effects were observed.

CONCLUSIONS

Ketorolac tromethamine was effective in the treatment of post-thoracotomy pain. Extrapleural intercostal nerve block allowed a significant reduction in the consumption of opioids. These analgesic techniques could be useful as low-risk, cost-effective and reproducible treatments when more effective techniques, such as epidural analgesia, are contraindicated.

[Blood preservation in thoracic surgery: feasibility and limitations]

The transfusion of homologous blood carries risks associated with reactions to transfusion and the transmission of diseases. Minimizing surgery-related blood use is therefore of utmost importance. However, the application of blood-saving methods in surgery is restricted by a number of factors. Thoracic surgery poses particular problems in this regard due to the type of diseases treated, patients' general status and the use of neoadjuvant chemotherapy protocols. The aim of this study was to analyse the feasibility of a blood conservation program for thoracic surgery. A detailed analysis of blood-sparing techniques was carried out and the factors influencing blood consumption were evaluated in the preoperative, intraoperative and postoperative periods. Although pre-operative autologus blood donation is an extremely important factor, its effect is limited in thoracic surgery since only a few patients are suitable candidates for such a procedure. Our personal experience confirms the difficulty of applying a blood sparing program to thoracic surgery. Nevertheless the risks associated to transfusions, especially those related to the use of homologous blood, can be reduced by optimizing existing blood sparing techniques or developing new hemostatic agents.

V delta 1+ gamma/delta T lymphocytes infiltrating human lung cancer express the CD8 alpha/alpha homodimer

Murine gamma/delta T lymphocytes localize to different epithelial tissues and are phenotypically distinct from peripheral gamma/delta T cell-populations in that they show limited TCR diversity, express the CD8 alpha/alpha homodimer and lack the CD8 beta chain. In humans, a compartmentalization of gamma/delta cells sharing similar phenotypic features has been documented to date only in the case of intestinal epithelium. In the present study we show that about half of V delta 1+ (as well as V delta 1-V delta 2-) gamma/delta lymphocytes, which can be selectively expanded from human lung cancers, coexpress the CD8 alpha/alpha homodimer. The accumulation of intraepithelial CD8+ gamma/delta+ lymphocytes might then be a more general phenomenon, possibly as a result of common mechanisms operating at those sites.

Self-expanding stents in the treatment of tracheobronchial obstruction

The self-expandable stainless steel stents (Gianturco, William Cook, Bjaeverskov, Denmark) used extensively in biliary ducts and the vascular system have recently been modified for use in the tracheobronchial tree. Between March 1991 and September 1992, six patients with unresectable tracheobronchial and mediastinal diseases were treated with the placement of one or more self-expanding stents under direct vision with a fiberoptic bronchoscope. All patients had been intubated for severe respiratory insufficiency. In all cases, immediate relief of respiratory symptoms was achieved and all patients were extubated 1 or 2 days after stent placement. Tolerance of the stents was excellent. No patient complained of pain, discomfort, or foreign body sensation. No infection or obstruction of the stents was observed. The chest roentgenogram and the bronchoscopies performed during follow-up have shown no change in the position of the stents. Our results seem promising since these devices provide effective palliation of airway obstructions and are well tolerated.

A critical assessment of the effects of aminoguanidine and ascorbate on the oxidative modification of LDL: evidence for interference with some assays of lipoprotein oxidation by aminoguanidine

Several lines of evidence support a role for oxidized low density lipoprotein (LDL) in the genesis of the atherosclerotic lesion. Hence, the effect of compounds with antioxidant properties on LDL oxidation assumes great significance. Ascorbate, a potent water-soluble chain-breaking antioxidant, has been shown to inhibit LDL oxidation. Aminoguanidine (AMG) is a pharmacological inhibitor of advanced non-enzymatic glycosylation. Recently it has been suggested that aminoguanidine might have an inhibitory effect on LDL oxidation, but total lipid peroxidation assayed by conjugated diene formation was not inhibited. Thus, in this study, we compared the effect of aminoguanidine with ascorbate to obtain a better appreciation of the effect of AMG on Cu(2+)-catalyzed LDL oxidation. Oxidative modification of LDL was monitored by assaying intermediates and end products of lipid peroxidation, conjugated dienes (CD), lipid peroxides (LPO), and relative electrophoretic mobility (REM). Apolipoprotein B-100 modification (increased fluorescence, fragmentation on SDS-PAGE, and 125I-labeled LDL degradation by human macrophages) was also measured. Ascorbate (100 microM) inhibited LDL oxidation by > 95%, as evidenced by all of the selected indices. Aminoguanidine (20 mM) substantially decreased thiobarbituric acid-reactive substances (TBARS) activity and lipid peroxide formation, but only partially prevented the increase of REM (-55%), apoB fluorescence (-39%), and degradation by macrophages (-54%). Unlike ascorbate, AMG failed to preserve alpha-tocopherol in LDL, prevent apoB-100 fragmentation, or inhibit conjugated diene formation during LDL oxidation. Furthermore, incubation of AMG with already oxidized LDL resulted in a significant decrease in TBARS activity and LPO, and 26.9% decrease in the REM of LDL.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgery following neoadjuvant MPV chemotherapy (mitomycin, cisplatin, vinblastine) in locally advanced (IIIa and IIIb) non-small cell lung cancer

From November 1990 to August 1993, 32 patients with non-small cell lung cancer (NSCLC) entered a multimodality treatment study with neoadjuvant Mitomycin, Cisplatin and Vinblastine (MPV), surgery and radiotherapy at the San Raffaele Hospital in Milan, Italy. Neoadjuvant chemotherapy was performed on an outpatient basis. To date 23 patients (11 stage IIIa and 12 stage IIIb) have completed the chemotherapy treatment and are available for evaluation of response, toxicity, surgical eligibility and resection rate. The overall major response to MPV chemotherapy was 87%. The overall resection rate after major response to treatment was 60% (90% in stage IIIa and 17% in stage IIIb). After a median follow-up of 21 months (8-31) 17 patients are still alive (74%). Ten patients (83%) who had a complete resection are alive after a median follow-up of 23 months (21-30) and eight of them (66%) are in complete pathological remission. No treatment-related mortality was observed. The authors conclude that MPV is a highly effective neoadjuvant regimen for NSCLC and is feasible on an outpatient basis. Favorable resection rates can be obtained in stage IIIa patients. Stage IIIb patients can be downstaged and undergo complete resection. A longer follow-up is needed to assess the impact of this multimodality approach on long-term survival and to evaluate the role of adjuvant radiotherapy.

Transgenic mice expressing high plasma concentrations of human apolipoprotein B100 and lipoprotein(a)

The B apolipoproteins, apo-B48 and apo-B100, are key structural proteins in those classes of lipoproteins considered to be atherogenic [e.g., chylomicron remnants, beta-VLDL, LDL, oxidized LDL, and Lp(a)]. Here we describe the development of transgenic mice expressing high levels of human apo-B48 and apo-B100. A 79.5-kb human genomic DNA fragment containing the entire human apo-B gene was isolated from a P1 bacteriophage library and microinjected into fertilized mouse eggs. 16 transgenic founders expressing human apo-B were generated, and the animals with the highest expression had plasma apo-B100 levels nearly as high as those of normolipidemic humans (approximately 50 mg/dl). The human apo-B100 in transgenic mouse plasma was present largely in lipoproteins of the LDL class as shown by agarose gel electrophoresis, chromatography on a Superose 6 column, and density gradient ultracentrifugation. When the human apo-B transgenic founders were crossed with transgenic mice expressing human apo(a), the offspring that expressed both transgenes had high plasma levels of human Lp(a). Both the human apo-B and Lp(a) transgenic mice will be valuable resources for studying apo-B metabolism and the role of apo-B and Lp(a) in atherosclerosis.

Three-step tumor pre-targeting in lung cancer immunoscintigraphy

Radiolabelled MoAbs have been used in both the diagnosis and the treatment of a variety of tumors. Recently, a three-step tumor pre-targeting strategy has been proposed to overcome one of the major limiting factors in radioimmunodetection: the low tumor-to-background ratio. We evaluated this pre-targeting protocol in 10 patients diagnosed as having pulmonary carcinoma. One milligram of biotinylated anti-CEA MoAb (FO23C5) was administered i.v. (1st step); 24 hours later 5 mg of avidin was injected i.v. (2nd step) followed by 100-500 ng of 111In-biotin (5 mCi) the day after (3rd step). Imaging was performed using single photon emission tomography (SPET). No toxicity and no adverse reactions were observed. Tumor was detected in 8 out of 10 patients. Mediastinal metastases were also localised in 2 out of 3 patients, and adrenal gland recurrency in 1 out of 2 patients. The tumor/background (normal lung), heart, liver and spine ratios were respectively 2.0, 1.0, 1.3 and 4.1 at 90 minutes post-injection. These preliminary data show that the three-step pretargeting method is safe and allows SPECT tumor localization soon after the injection of the radiolabel. In the future, the use of MoAbs with higher specificity could result in improved tumor-targeting, and in the possibility of lung cancer radioimmunotherapy.

Expression of human apolipoprotein B100 in transgenic mice. Editing of human apolipoprotein B100 mRNA

Apolipoprotein B (apoB) is a large glycoprotein that circulates in plasma as a major constituent of numerous lipoproteins. ApoB exists in two forms: apoB48 and apoB100. ApoB48 is identical in sequence to the N-terminal region of apoB100 and is generated by sequence-specific mRNA editing of the apoB100 transcript. Here, we describe the development of a line of mice expressing a human apoB transgene driven by promoter/enhancer sequences from the transthyretin gene. In these mice, immunodetectable human apoB100 is synthesized by the liver, kidney, and brain. Human apoB100 is found in low concentration (approximately 0.1 mg/dl) in the plasma of the transgenic mice and circulates in the low density lipoprotein fraction. The hepatic human apoB100 transcripts undergo mRNA editing at only slightly lower efficiency than the endogenous mouse apoB100 message. Therefore, there is no absolute species specificity to the apoB100 mRNA editing process.

Adjuvant treatment of stage I lung cancer with high-dose vitamin A

PURPOSE

Vitamin A and retinoids are strong inhibitors of epithelial cancer promotion and progression in experimental carcinogenesis. This study examined whether they may prevent the occurrence of upper aerodigestive cancer in subjects heavily exposed to tobacco smoking, such as patients already cured of an early-stage lung cancer.

PATIENTS AND METHODS

The adjuvant effect of high-dose vitamin A was tested on 307 patients with stage I non-small-cell lung cancer. After curative surgery, patients were randomly assigned to either a group prescribed retinol palmitate administration (orally 300,000 IU daily for 12 months) or a control group prescribed no treatment.

RESULTS

After a median follow-up of 46 months, the number of patients with either recurrence or new primary tumors was 56 (37%) in the treated arm and 75 (48%) in the control arm. Eighteen patients in the treated group developed a second primary tumor, and 29 patients in the control group developed 33 second primary tumors. A statistically significant difference in favor of treatment was observed concerning time to new primary tumors in the field of prevention (P = .045, log-rank test). The treatment difference in terms of disease-free interval was close to statistical significance (P = .054, log-rank test) and just significant when adjusted for primary tumor classification (P = .038, Cox regression model).

CONCLUSION

Daily oral administration of high-dose vitamin A is effective in reducing the number of new primary tumors related to tobacco consumption and may improve the disease-free interval in patients curatively resected for stage I lung cancer. The impact of such a treatment on survival needs to be further explored.

Sequence polymorphisms in the apolipoprotein (a) gene. Evidence for dissociation between apolipoprotein(a) size and plasma lipoprotein(a) levels

Apolipoprotein(a) [apo(a)], an apolipoprotein unique to lipoprotein(a) [Lp(a)], is highly polymorphic in size. Previous studies have indicated that the size of the apo(a) gene tends to be inversely correlated with the plasma level of Lp(a). However, several exceptions to this general trend have been identified. Individuals with apo(a) alleles of identical size do not always have similar plasma concentrations of Lp(a). To determine if these differences in plasma Lp(a) concentrations were due to sequence variations in the apo(a) gene, we examined the sequences of apo(a) alleles in 23 individuals homozygous for same-sized apo(a) alleles. We identified four single-strand DNA conformation polymorphisms (SSCPs) in the apo(a) gene. Of the 23 homozygotes, 21 (91%) were heterozygous for at least one of the SSCPs. Analysis of a family in which a parent was homozygous for the same-sized apo(a) allele revealed that each allele, though identical size, segregated with different plasma concentrations of Lp(a). These studies indicate that the apo(a) gene is even more polymorphic in sequence than was previously appreciated, and that sequence variations at the apo(a) locus, other than the number of kringle 4 repeats, contribute to the plasma concentration of Lp(a).

Mechanisms of high-density lipoprotein reduction after probucol treatment: changes in plasma cholesterol esterification/transfer and lipase activities

Probucol treatment results in a significant reduction of plasma high-density lipoprotein (HDL) levels. Since the remodeling of HDL within the plasma compartment is a crucial determinant of HDL levels, the activities of several factors participating in the process, ie, lecithin:cholesterol acyltransferase (LCAT), cholesteryl ester transfer protein (CETP), and lipoprotein and hepatic lipases (LPL, HL), were evaluated in 15 hypercholesterolemic patients treated with probucol (1 g/d) for 8 weeks. Drug treatment was associated with significant reductions of HDL cholesterol ([HDL-C] -32%), HDL2-C (-65%), HDL3-C (-22%), apolipoprotein (apo)A-I (-27%), and apo A-II (-11%) levels and with the accumulation of small HDL in plasma. CETP activity increased by 48%, with minor changes in LCAT (-7%), LPL (+4%), and HL (-7%) activities. By linear regression analysis, CETP activity correlated inversely with HDL-C, HDL2-C, and apo A-I levels (r = -.63, -.52, and -.73, respectively) and with HDL particle size. In multivariate analysis, CETP activity was the strongest predictor of HDL-C levels, apo A-I levels, and HDL particle size. The hypothetical mechanism of probucol is a stimulation of CETP activity, resulting in the formation of triglyceride (TG)-enriched HDL. These are acted on by HL, leading to the accumulation of small HDL in plasma.

Atherogenesis in transgenic mice expressing human apolipoprotein(a)

Elevated plasma levels of the lipoprotein Lp(a) are associated with increased risk for atherosclerosis and its manifestations, myocardial infarction, stroke and restenosis (for reviews, see refs 1-3). Lp(a) differs from low-density lipoprotein by the addition of the glycoprotein apolipoprotein(a), a homologue of plasminogen that contains many tandemly repeated units which resemble the fourth kringle domain of plasminogen, and single homologues of its kringle-5 and protease domain. As plasma Lp(a) concentration is strongly influenced by heritable factors and is refractory to most drug and dietary manipulation, the effects of modulating it are difficult to mimic experimentally. In addition, the absence of apolipoprotein(a) from virtually all species other than primates precludes the use of convenient animal models. Here we show that transgenic mice expressing human apolipoprotein(a) are more susceptible than control mice to the development of lipid-staining lesions in the aorta, and that apolipoprotein(a) co-localizes with lipid deposition in the artery walls.

Reconstitution of lipoprotein(a) by infusion of human low density lipoprotein into transgenic mice expressing human apolipoprotein(a)

Lipoprotein(a) (Lp(a)) is an atherosclerosis-causing lipoprotein that circulates in human plasma as a complex of low density lipoprotein (LDL) and apolipoprotein(a) (apo(a)). It is not known whether apo(a) attaches to LDL within hepatocytes prior to secretion or in plasma subsequent to secretion. Here we describe the development of a line of mice expressing the human apo(a) transgene under the control of the murine transferrin promoter. The apo(a) was secreted into the plasma, but circulated free of lipoproteins. When human (h)-LDL was injected intravenously, the circulating apo(a) rapidly associated with the lipoproteins, as determined by nondenaturing gel electrophoresis. Human HDL and mouse LDL had no such effect. When h-VLDL was injected, there was a delayed association of apo(a) with the lipoprotein fraction which suggests that apo(a) preferentially associated with a metabolic product of VLDL. The complex of apo(a) with LDL formed both in vivo and in vitro was resistant to boiling in the presence of detergents and denaturants, but was resolved upon disulfide reduction. These studies suggest that apo(a) fails to associate with mouse lipoproteins due to structural differences between human and mouse LDL, and that Lp(a) formation can occur in plasma through the association of apo(a) with circulating LDL.

Apolipoprotein(a) gene accounts for greater than 90% of the variation in plasma lipoprotein(a) concentrations

Plasma lipoprotein(a) [Lp(a)], a low density lipoprotein particle with an attached apolipoprotein(a) [apo(a)], varies widely in concentration between individuals. These concentration differences are heritable and inversely related to the number of kringle 4 repeats in the apo(a) gene. To define the genetic determinants of plasma Lp(a) levels, plasma Lp(a) concentrations and apo(a) genotypes were examined in 48 nuclear Caucasian families. Apo(a) genotypes were determined using a newly developed pulsed-field gel electrophoresis method which distinguished 19 different genotypes at the apo(a) locus. The apo(a) gene itself was found to account for virtually all the genetic variability in plasma Lp(a) levels. This conclusion was reached by analyzing plasma Lp(a) levels in siblings who shared zero, one, or two apo(a) genes that were identical by descent (ibd). Siblings with both apo(a) alleles ibd (n = 72) have strikingly similar plasma Lp(a) levels (r = 0.95), whereas those who shared no apo(a) alleles (n = 52), had dissimilar concentrations (r = -0.23). The apo(a) gene was estimated to be responsible for 91% of the variance of plasma Lp(a) concentration. The number of kringle 4 repeats in the apo(a) gene accounted for 69% of the variation, and yet to be defined cis-acting sequences at the apo(a) locus accounted for the remaining 22% of the inter-individual variation in plasma Lp(a) levels. During the course of these studies we observed the de novo generation of a new apo(a) allele, an event that occurred once in 376 meioses.

Activity profile of gemfibrozil on the major plasma lipoprotein parameters

Gemfibrozil (G) is a widely used and highly effective fibric acid derivative. It acts both on lipoprotein disorders characterized by hypertriglyceridemia, as well as in hyperchlolesterolemia. The results of two separate studies are summarized, in order to elucidate the differential activity profile of the drug on the major plasma lipoprotein parameters. In a group of hypertriglyceridemic patients (Study I) the major activity of G was on the VLDL cholesterol (C) and triglyceride levels (respectively -40.4 and -35.7%), associated with a marked increase of the HDL-C levels, in particular in the HDL3 subfraction. In addition, apolipoprotein B levels were significantly reduced (-12%) in all treated patients. In Study II, treatment with G in severe hypercholesterolemia was compared to that with pravastatin, a major hydroxymethylglutaryl coenzyme A reductase inhibitor. G, in these patients, markedly reduced both total (-21.6%) and LDL-cholesterol (-24.4%) levels. The increase of HDL-C was less marked than in type IV patients but G, similarly to pravastatin, induced a significant reduction of apolipoprotein B, together with an increase (+19.2%) of apolipoprotein AII levels. These findings indicate that the activity profile of G is wider than expected and that it may include a reduction of LDL levels in severely hypercholesterolemic patients. The mechanism of this latter change is difficult to establish, although it may also be related to an improved delipidation of LDL, resulting in a more efficient interaction with peripheral high affinity receptors.

The social and vocational outcome of spinal cord injury patients

Functional status, perception of adjustment, occupational outcome and social functioning were investigated in a group of spinal cord injury (SCI) patients (mean age 34, range 10-74 years) seen at a specialised spinal unit over the period January 1984-December 1988. Functional status was assessed using a standardised scale measuring patients' performance of specific tasks, and other measures of outcome were investigated by a structured interview. Almost two thirds (68%) of the patients were independent according to the standardised scale (33% quadriplegic and 84% paraplegic). Patients' autonomy appeared to be threatened by architectural barriers in and about the house: approximately one third (34%) of those classified as 'independent' on the standardised rehabilitation scale used needed some help in their everyday life. A negative occupational outcome emerged: compared to the pre-morbid situation, 43 patients (44%) were worse off; 48 (49%) did not experience substantial changes--though it must be noted that 68% of these (33/48) were virtually unemployed (ie student, home maker, retired, unemployed) before the injury; and for 6 (7%) some improvement took place. With a multivariate analysis age was the only statistically significant predictor of poor occupational outcome, with older patients being worse off irrespective of the extent of disease and functional autonomy. The paper discusses these results and stresses the need for integrating results based on the use of standardised rehabilitation scales with the analysis of potential barriers influencing a patient's ability to exploit his/her autonomy.

Probucol increases cholesteryl ester transfer protein activity in hypercholesterolaemic patients

Probucol, a widely used lipid lowering drug, reduces both low- and high-density (LDL and HDL) lipoprotein levels and can induce a regression of tissue lipid deposits in both animals and man. The suggested mechanism(s) involve the prevention of LDL oxidative modifications and, possibly, an improvement in the reverse cholesteryl ester transport system. Probucol administration to 10 hypercholesterolaemic patients increased the activity of the cholesteryl ester transfer protein (CETP) by 50%. The rise of CETP activity was significantly related with the plasma steady-state drug levels (r = 0.51, P less than 0.005), thus suggesting that probucol may directly stimulate CEPT synthesis and/or release. Furthermore, CETP activity was inversely related with HDL-cholesterol levels, both in the whole series of 10 patients (r = -0.56, P less than 0.001) and, more so, in the single individuals (r between -0.77 and -0.97), thus suggesting that the reduction of plasma HDL-cholesterol levels is a direct consequence of CETP stimulation. These findings support the hypothesis that an improvement in the reverse cholesteryl ester transport is a major mechanism of probucol and that this may explain the drug induced plasma lipoprotein changes.

Management of lipoprotein-X accumulation in severe cholestasis by semi-selective LDL-apheresis

Liver disorders characterized by prolonged bile stasis are often associated with the accumulation of an abnormal lipoprotein, lipoprotein-X (LP-X), in plasma. LP-X is separated in the low-density lipoprotein (LDL) density range, but lacks apolipoprotein B and does not interact with the LDL receptor; LP-X can cause hyperlipidemia, cutaneous xanthomas, and worsening of arterial disease. We report the case of a patient with severe cholestasis, markedly elevated plasma cholesterol levels (26.8 to 31.5 mmol/L), mainly due to a massive accumulation of LP-X in plasma, and diffuse xanthomas. To reduce the elevated cholesterol levels, the patient was given extracorporeal treatment aimed at removing atherogenic lipoprotein (LDL-apheresis). LDL-apheresis was performed at weekly or bi-weekly intervals, either by a semi-selective technique using filters with a defined pore diameter (double filtration, DF) or by a more selective technique using dextran-sulfate-cellulose (DSC) columns able to bind LDL. The semi-selective DF technique proved more effective than DSC, removing 48% of total cholesterol (compared to 30% with DSC), and lowering cholesterol levels to 11.1 mmol/L in 6 weeks. DF removed both LDL and LP-X from plasma, whereas DSC selectively decreased the LDL content. The reduction of plasma cholesterol levels was associated with a complete regression of the xanthomas, supporting DF apheresis as a first-choice treatment for patients with massive LP-X accumulation due to cholestasis.

Predictability of low-density lipoprotein levels during apheretic treatment of hypercholesterolaemia

The efficiency and efficacy of low-density lipoprotein (LDL) apheresis performed with a dextran sulphate cellulose (DSC) regenerating unit were tested in five familial hypercholesterolaemic patients. LDL apheresis was repeated four times at both bi-weekly and weekly intervals, processing one plasma volume each time. The efficiency of the procedure (i.e., the extent of lipoprotein removal) was nearly identical with both schedules. Efficacy parameters, i.e., decreases of plasma total and LDL cholesterol (TC and LDL-C) and apo B, were highly correlated (r greater than 0.96) with preapheresis levels, allowing an accurate prediction of the absolute lipid removal in the single individual. Plasma triglycerides, high-density lipoprotein cholesterol, apo A-I and apo A-II recovered rather rapidly, reaching 91-96% of the pre-apheresis values in 48 hours; the recovery of TC, LDL-C and apo B was much slower, with a relatively rapid early phase (80% recovery after about 7 days) followed by a successive slower rise. This pattern was highly reproducible in the single patient, allowing the definition of a simple mathematical model for an accurate (error less than 20%) prediction of the individual process. Based on this model one can design the treatment schedule necessary to maintain lipid levels within the desired range in the single individual. The hypolipidaemic efficacy of DSC apheresis appears, otherwise, not to be dependent upon the procedure per se, but on other individual factors, e.g. the amount of removable lipoproteins and the rate of lipid recovery; both can be predicted with sufficient accuracy.

Impaired efficacy of selective LDL-apheresis in primary biliary cirrhosis

Low-density lipoprotein apheresis (LDL-apheresis) was done with either cascade filtration (DF) or dextran sulfate cellulose adsorption (DSC) in a patient with primary biliary cirrhosis who developed severe dyslipidemia associated with cholestasis and accumulation of lipoprotein-X (LP-X). The extracorporeal treatment was initially performed weekly, and resulted in a sharp drop in total cholesterol from 1038 to 430 mg/dl. During the next four months the patient was treated every 10-15 days, and pre-apheresis cholesterol levels were maintained between 438 and 505 mg/dl, until an orthotopic liver transplantation was successfully performed. With semi-selective DF a mean 47.1% of total cholesterol was removed per procedure compared to 30.0% with DSC, although the volume of treated plasma was 38.0 vs 49.9 ml/kg body weight. The changes in plasma cholesterol levels during DSC and DF showed that the kinetics of cholesterol removal were similar with both techniques, but the efficacy differed; DF removed both LDL and LP-X from plasma, whereas DSC selectively lowered the LDL content. Cascade filtration may therefore be considered as a first-choice treatment for patients with LP-X accumulation due to cholestasis.

Laboratory evaluation during high-dose vitamin A administration: a randomized study on lung cancer patients after surgical resection

The laboratory findings in patients receiving high-dose vitamin A as adjuvant treatment for stage I lung cancer are here reported. A group of 283 patients were randomized to either treatment with retinyl palmitate (300,000 IU daily for 12 months) or standard follow-up, and are now evaluable after a median observation period of 28 months. At regular intervals, all the patients underwent a physical examination, chest roentgenogram, blood chemistries, haematological assays, hepatic and renal function tests and determinations of serum triglycerides and cholesterol. Serum transaminase abnormalities were of similar magnitude in cases and controls, while gamma-glutamyltransferase levels were abnormally elevated in 69% of the treated patients compared to 39% of controls (mean values 149 vs 57 IU/l at 24 months, P less than 0.05). Serum triglyceride concentrations over 150 mg/dl were seen in 74% of treated patients compared to 43% of controls at 12 months, the average concentration was 283 mg/dl compared to 179 mg/dl (P less than 0.05). Cholesterol levels showed a modest, non-significant rise with time in both groups, and there was no other laboratory evidence of toxicity attributable to vitamin A. Serum retinol and retinol-binding protein, assessed on a limited sample of patients, were higher in the treatment arm (P less than 0.05) at 12 months. In our experience 300,000 IU/day of retinyl palmitate can be administered as a possible chemopreventive agent with reasonable safety for up to 2 years.

Safety of high-dose vitamin A. Randomized trial on lung cancer chemoprevention

The paper reports on the efficacy and side effects of high-dose vitamin A, administered as adjuvant treatment for resected stage I lung cancer in a randomized clinical trial. After a median follow-up of 28 months, 283 patients were evaluable: 138 allocated to treatment with retinol palmitate (300,000 IU daily for at least 12 months) and 145 to standard observation. The clinical results available to date do well justify a continuation of the study. Skin dryness and desquamation were the most frequent symptoms, affecting 60% of all treated patients. Other symptoms such as dyspepsia, headache, nosebleeds and mild hair loss occurred in less than 10% of patients, and were self-terminating. Only in 4 patients (3%) was the treatment interrupted because of symptoms potentially related to vitamin A administration. As for laboratory tests, gamma-GT levels were abnormally elevated in 69% of treated patients vs. 39% of controls at 24 months (mean 149 vs. 58 IU/l; p less than 0.05). Serum triglyceride concentrations over 150 mg/dl were seen in 74% of treated patients vs. 43% of controls at 12 months (mean 283 vs. 179 mg/dl; p less than 0.05). There were no other laboratory signs of toxicity attributable to vitamin A. In our experience, high-dose retinoyl palmitate administration was a well-tolerated and safe treatment. The long-term impact on lipid metabolism still remains to be determined.

In vitro activity of probucol on cholesteryl ester transport

Probucol treatment in hypercholesterolemic patients promotes the transfer of cholesteryl esters from high-density-lipoproteins (HDL) to lower-density lipoproteins. In vitro studies, on hypercholesterolemic plasma incubated with or without probucol, show that drug binding to lipoprotein particles does not affect either cholesteryl ester transfer, or the lipoprotein modifications occurring in the process. Probucol stimulates reverse cholesteryl ester transfer in vivo apparently by mechanisms independent of lipoprotein binding.