Predictive role of FAS for trabectedin in second lines of advanced soft tissue sarcoma (ASTS): A Spanish group for research on sarcoma (GEIS) study

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Background: There are currently several second-line options for the treatment of ASTS as gemcitabine combinations, trabectedin, pazopanib, eribulin or olaratumab plus doxorubicin in cases where anthracyclins are still possible. There is an unmet need for predictive biomarkers which hinders the rational selection of the best sequence in second line. We already published the prognostic value of FAS in first line of ASTS while this study analyzes its predictive role in different second line schemes. Methods: Most relevant selection criteria for this study were having received trabectedin in 2nd line or beyond for ASTS, progressive disease after at least one previous line for ASTS and signed CI. A TMA was set up for FAS staining (Cell Signaling) with blocks from diagnostic time. Two expert blinded pathologists reviewed and classified the cases as negative, weak or strong. Kaplan–Meier estimations were used for time-to-event variables and the log-rank test was used to compare groups. Results: A series of 198 patients accomplished selection criteria. Metastases at diagnosis occurred in 46 (24%) and median time to metastases was 18.8 months (CI 16,3; 21.3). Previous line to trabectedin consisted of gemcitabine combination 83 (42%), Doxorubicin-based 65 (33%) and others 50 (25%). Median PFS for previous and trabectedin lines were 3.5 (2.8-4.2) and 3.4 (2.8-4) months respectively. FAS positive entailed significantly better PFS for the previous trabectedin line: 4.1 (1.5-6.7) vs 3.0 (2.5-3.5) months, p = 0.01 whereas FAS positive was related with worse PFS for the trabectedin line 2.5 (2.2-2.8) vs 3.7 (2.7-4.8) months, p = 0.028. These results were more notorious for L-sarcoma cases: 7.0 (3.6-10.5) vs 4.3 (1.9-6.6) months, p = 0.017 in previous line and 2.4 (2.2-2.6) vs 6.5 (3.8-9.3) months, p < 0.001 in trabectedin. From trabectedin administration, FAS+ had significantly worse OS especially in L-sarcomas: 11.9 (5.2-18.7) vs 21.7 (12.7-30.8) months, p = 0.002. Conclusions: FAS showed predictive value in PFS and OS for trabectedin administration in ASTS. The different prognostic role of FAS across distinct lines and its relevance in L-sarcomas deserve further attention.

Acute Toxicity of Intravenously Administered Microfabricated Silicon Dioxide Drug Delivery Particles in Mice

BACKGROUND AND OBJECTIVE

Microfabricated particles with nanosized features may serve an important role in the next generation of drug delivery vehicles. Microfabrication (micro-electromechanical systems) technologies offer the promise of both structural elements (e.g., pores, reservoirs) and electromechanical features (e.g., timers, valves, actuators) built into a single particle. In order to serve as carriers to deliver drugs to systemic sites of action, such as tumors, the particles must be safe to administer intravenously. An acute safety study was performed in a mouse model, using intravenous injection of solid silicon dioxide particles created to simulate the size and shape of potential targeted drug delivery vehicles.

DESIGN

Two-micron thick, square and circular, parallelepiped-shaped particles were produced with varying sizes of 2 microm, 5 microm and 10 microm using microfabrication techniques and injected into groups of mice (six mice per group) over a range of doses. End-points included acute lethality, clinical signs of toxicity and weight loss. Sections of major organs were sampled for histological examination.

RESULTS

At dose levels of 1 x 10(8) particles per mouse, circular particles of 2 microm and 5 microm showed no signs of acute toxicity. Similar results were obtained with the 2 microm and 5 microm square silicon dioxide particles; however, 14-day necropsy indicates fewer 5 microm circular particles in the lung than 5 microm square particles, indicating that the shape of the particles may impact on safety. Acute lethality was observed for 10 microm particles; none of the mice injected with the 10 microm particles survived except at very low dose levels of 6 x 10(5) particles per mouse.

CONCLUSIONS

Solid silicon particles greater than 5 microm in their largest dimension are cleared in the lungs and are not safe for intravenous delivery. Particles of 2-5 microm in size do not lodge predominantly in the lung and do not cause acute toxicity, but accumulate in organs such as the liver and spleen. Possible chronic toxicities associated with organ uptake of such non-biodegradable particles have yet to be addressed.

Pindolol suppresses serotonergic neuronal activity and does not block the inhibition of serotonergic neurons produced by 8-hydroxy-2-(di-n-propylamino)tetralin in awake cats

Clinical studies have shown that pindolol can enhance the effects of antidepressant drugs, presumably by acting as an antagonist at somatodendritic 5-hydroxytryptamine (5-HT)(1A) autoreceptors, which regulate the firing rate of central serotonergic neurons. The current study characterized the action of pindolol on the single-unit activity of serotonergic neurons in the dorsal raphe nucleus of freely moving cats. (+/-)-Pindolol produced a dose-dependent inhibition of neuronal activity after i.v. (ED(50) = 0.25 mg/kg) and s.c. (ED(50) = 1.23 mg/kg) administration. The active enantiomer (-)-pindolol (1 mg/kg i.v.) also suppressed neuronal activity (maximal decrease, 88%). Upon p.o. administration, (+/-)-pindolol (10 mg/kg) produced a marked, long-acting suppression of neuronal activity similar to that observed after s.c. administration. In all cases, the reduction in firing rate produced by pindolol was completely reversed by low doses of N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]-ethyl]-N-(2-pyridinyl)cycloh exanecarboxamide (WAY-100635) (0.1 mg/kg i.v. or 0.2 mg/kg s.c.), a selective 5-HT(1A) antagonist. Systemic administration of (-)-tertatolol (1-5 mg/kg i.v.), another beta-adrenoceptor blocker/putative 5-HT(1A) antagonist, had no significant effect on neuronal activity. The ability of i.v. (+/-)-pindolol (0.1-1 mg/kg) to reverse the suppression of serotonergic neuronal activity produced by 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (10 microg/kg i.v.), a selective 5-HT(1A) agonist, also was examined. (+/-)-Pindolol had no appreciable effect on the action of 8-OH-DPAT. In contrast, the 5-HT(1A) antagonist drugs WAY-100635 (0.1 mg/kg i.v. ), 4-fluoro-N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl benzamide (0.1 mg/kg, i.v.), N-tert-butyl-3-(4-(2-methoxyphenyl)piperazin-1-yl)-2-phenylprop anamid e [(S)-WAY-100135] (0.5 mg/kg i.v.), and (-)-tertatolol (1-5 mg/kg i. v.) reversed the effect of 8-OH-DPAT to varying degrees. Overall, these results indicate that pindolol acts as an agonist rather than an antagonist at 5-HT(1A) autoreceptors in awake animals.

Pindolol, a putative 5-hydroxytryptamine(1A) antagonist, does not reverse the inhibition of serotonergic neuronal activity induced by fluoxetine in awake cats: comparison to WAY-100635

The ability of pindolol to enhance the clinical antidepressant response to selective serotonin reuptake inhibitors (SSRIs) is generally attributed to a blockade of the feedback inhibition of serotonergic neuronal activity mediated by somatodendritic 5-hydroxytryptamine (5-HT)(1A) autoreceptors. The current study examined the ability of pindolol to restore the single-unit activity of serotonergic dorsal raphe nucleus neurons in awake cats after acute treatment with the SSRI fluoxetine. The effects of pindolol were compared with those of N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohe xanecarboxamide (WAY-100635), a selective 5-HT(1A) receptor antagonist. Systemic administration of fluoxetine (0.5 and 5 mg/kg i. v.) decreased neuronal firing rates to approximately 50 and 1%, respectively, of baseline levels. The subsequent administration of cumulative doses of (+/-)-pindolol (0.1-5 mg/kg i.v.) failed to reverse the neuronal inhibition produced by either dose of fluoxetine. In addition to lacking efficacy as an antagonist in these experiments, (+/-)-pindolol produced an additional decrease in neuronal activity in animals pretreated with the low dose of fluoxetine. The active enantiomer, (-)-pindolol (1 mg/kg i.v.), also was ineffective in restoring neuronal activity after fluoxetine. In contrast, systemic administration of WAY-100635 completely reversed the effect of fluoxetine (5 mg/kg) at low doses (0.025 mg/kg i.v.), and further elevated the firing rate of these neurons above prefluoxetine baseline levels. Overall, these results indicate that pindolol, unlike WAY-100635, lacks appreciable antagonist activity at 5-HT(1A) autoreceptors. Thus, the clinical efficacy of pindolol in augmenting the antidepressant response to SSRIs, such as fluoxetine, may be unrelated to a restoration of serotonergic neuronal activity.

The use of cardiac biopsy to demonstrate reduced cardiotoxicity in AIDS Kaposi's sarcoma patients treated with pegylated liposomal doxorubicin

BACKGROUND

Pegylated liposomal doxorubicin (PL-DOX) has been shown in preclinical models to induce less cardiotoxicity than non-liposomal doxorubicin. Endomyocardial biopsy is a highly sensitive and specific method for detecting anthracycline-induced cardiac damage.

PATIENTS AND METHODS

Myocardial tissue from ten KS patients who had received cumulative PL-DOX (20 mg/m2/biweekly) of 440-840 mg/m2 was evaluated for evidence of anthracycline-induced cardiac damage. Controls were assembled from patients who had received cumulative doxorubicin doses of 174-671 mg/m2 in two earlier cardiac biopsy protocols. Two control groups were selected on the basis of both cumulative (+/- 10 mg/m2) and peak doxorubicin dose (60 or 20 mg/m2, control group 1), or peak dose alone (20 mg/m2, control group 2).

RESULTS

PL-DOX patients had significantly lower biopsy scores compared with those of doxorubicin controls despite higher cumulative doses of anthracycline. The median biopsy scores for the PL-DOX and doxorubicin groups, respectively, were 0.3 vs. 3.0 (P = 0.002, Cochran-Mantel-Haenszel row mean difference test) for group 1 and 1.25 for group 2 (P < 0.001, Wilcoxon rank-sum test).

CONCLUSIONS

Less severe cardiac changes were seen in patients given PL-DOX relative to historical control patients given comparable cumulative doses of doxorubicin.

Changes in serotonin level and turnover in discrete hypothalamic nuclei after pinealectomy and melatonin administration to rats

The influence of the pineal gland on the hypothalamic serotonergic function was examined by studying the effects of long-term pinealectomy (1 month) and melatonin replacement (500 micrograms/kg; 10 days) on serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content as well as on the in vivo 5-HT synthesis rate in discrete hypothalamic nuclei. Pinealectomy was followed by a significant decrease of 5-HT content in the anterior hypothalamic nuclei (AHN) and the ventromedial hypothalamic nuclei (VMHN), and also in 5-HIAA content in lateral (LPON) and medial preoptic nuclei (MPON). The 5-HT synthesis rate, estimated from the accumulation of 5-hydroxytryptophan after blockade of the 1-amino acid decarboxylase activity, were also decreased in the AHN and the paraventricular hypothalamic nuclei (PVHN) of pinealectomized rats. In contrast, an enhanced 5-HT synthesis rate and basal 5-HIAA content were found in the suprachiasmatic nuclei (SCN) after pinealectomy. Daily treatment with melatonin for 10 days reversed most of the effects induced by pinealectomy. Thus, melatonin increased the levels of 5-HT in the AHN and VMHN, and slightly increased the 5-HIAA content in preoptic nuclei. In addition, melatonin increased the 5-HT synthesis rate in the AHN and VMHN, but also in the MPON, VMHN and dorsomedial hypothalamic nuclei (DMHN) where pinealectomy had no effect. By contrast, melatonin treatment did not affect SCN 5-HT synthesis rate, although it decreased 5-HIAA levels. The results demonstrate that melatonin is able to stimulate 5-HT metabolism in most of the hypothalamic areas, but inhibits SCN 5-HT function. Some of the effects of melatonin seems to be exerted by modulating the synthesis of the amine, although melatonin likely also interacts with other regulatory processes of 5-HT function (i.e. release/uptake). The well defined presence of melatonin receptors in the rat SCN, and its absence in other hypothalamic structures, suggest that this may be the mechanism mediating the differential response to endogenous melatonin. Moreover, the larger effect of exogenous melatonin in relation to pinealectomy suggests the presence of melatonin unespecific effects possibly owing to supraphysiological doses. The present findings may be relevant for the mode of action of melatonin and its implication in several endocrine and behavioral functions mediated by serotonergic neurons.

Doxorubicin encapsulated in sterically stabilized liposomes is superior to free drug or drug-containing conventional liposomes at suppressing growth and metastases of human lung tumor xenografts

Liposomes containing polyethylene glycol-derivatized phospholipids are able to evade the reticuloendothelial system and thereby remain in circulation for prolonged periods. We report here that doxorubicin encapsulated in these sterically stabilized liposomes (S-DOX) suppresses the growth of established human lung tumor xenografts in severe combined immunodeficient (SCID) mice and inhibits the spontaneous metastases of these tumors. The enhanced therapeutic efficacy of S-DOX compared to free doxorubicin was demonstrated in two independent human/mouse models. In the first model, S-DOX inhibited the growth of a human non-small cell lung tumor xenograft established orthotopically in the lungs of SCID mice. Treatment of these mice with S-DOX, but not with free drug, suppressed the growth of the tumor in the lung, prevented metastasis from the lung, and enhanced survival percentage. In another model, the human lung tumor is engrafted into gonadal fat pad of SCID mice. Human tumor xenografts grow floridly in this site of engraftment, and the tumor spreads from this primary site into the peritoneal cavity and subsequently reaches the liver and lung. In this model, free drug suppressed the growth of the primary tumor but had no effect upon the subsequent spread of the tumor into the peritoneal cavity, liver, and lung. In contrast, treatment of the tumor-bearing mice with S-DOX (but not with doxorubicin in conventional liposomes) suppressed the tumor spread to the peritoneal cavity, completely arrested metastasis to the liver and lung, and suppressed the growth of the primary tumor xenograft. This report provides the first evidence that antitumor drugs delivered by sterically stabilized liposomes can arrest the metastasis of human tumor xenografts.

Doxorubicin encapsulated in liposomes containing surface-bound polyethylene glycol: pharmacokinetics, tumor localization, and safety in patients with AIDS-related Kaposi's sarcoma

A study of the plasma pharmacokinetics, tumor localization, and safety of a single dose of doxorubicin encapsulated in liposomes containing surface-bound polyethylene glycol (PEG-liposomal doxorubicin) was conducted in patients with Kaposi's sarcoma (KS) as a manifestation of acquired immune deficiency syndrome (AIDS). Eighteen patients with AIDS-KS diagnosed by examination of biopsy specimens were randomly assigned to receive either standard doxorubicin or PEG-liposomal doxorubicin. Consecutive participants were entered at three dose levels (10, 20, and 40 mg/m2) in ascending fashion. Clearance of PEG-liposomal doxorubicin was 0.034 L/h/m2 to 0.108 L/h/m2, volume of distribution (Vd) was 2.2 L/m2 to 4.4 L/m2, and half-lives (t1/2) of the initial decline in the plasma concentration-time curve and of the terminal decline were 3.77 hours and 41.3 hours, respectively. Seventy-two hours after administration, doxorubicin levels observed in lesions of patients receiving PEG-liposomal doxorubicin were 5.2 to 11.4 times greater than those found in patients given comparable doses of standard doxorubicin. PEG-liposomal doxorubicin and standard doxorubicin were roughly equipotent in producing toxicity. Encapsulation in liposomes containing surface-bound PEG significantly limits the distribution and elimination of doxorubicin, results in greater accumulation of the drug in KS lesions 72 hours after dosing than does standard doxorubicin, and may improve drug efficacy and therapeutic index in the treatment of AIDS-KS.

Congenital ptosis: results of surgical management

PURPOSE

To determine the visual and cosmetic outcome following the surgical correction of isolated congenital ptosis.

METHODS

A retrospective review of the outcome of isolated congenital ptosis corrected under the supervision of one surgeon at The Children's Hospital, Camperdown, between January 1983 and January 1993 was examined. Some 65 patients with 80 involved eyes were identified; 30 eyes underwent a levator resection procedure, 40 eyes underwent a brow suspension using donor stored fascia lata, and in 10 eyes a brow suspension was performed using mersilene mesh.

RESULTS

In 78 eyes of 63 patients, a good cosmetic result was achieved. In two patients (two eyes) a poor cosmetic result was achieved. These two patients refused further surgery following an undercorrection of their initial ptosis. The recurrence rates for the primary procedures were 16.7% for levator resection procedures, 35% for brow suspension procedures using donor fascia lata, and 30% for brow suspension surgery using mersilene mesh. Some 35.3% of eyes following mersilene slings required further surgery for granulomas and exposed mersilene mesh compared with 6% having similar complications with stored fascia lata. Nine patients (11.25%) had reduced visual acuity (one line or more on the Snellen chart or its equivalent with the other tests used) on the operated side. Only one patient was found to have significant astigmatism.

CONCLUSIONS

An acceptable cosmetic result was achieved with one operation in 75.3% of cases. In 20.8% of cases a second operation was required and in 3.9% of cases three or more operations were required. This series supports the view that where possible, levator resection is the preferred form of surgery to correct congenital ptosis. When the levator function is inadequate, brow suspension is performed. The use of donor fascia lata resulted in a good cosmetic appearance with a low occurrence of surgical side effects. Amblyopia, when strictly defined, occurred in 11.25% of eyes despite early surgery for severe cases and intensive amblyopia therapy. Management requires repeated follow up for early detection and introduction of occlusion therapy or surgical ptosis correction.

Effects of pinealectomy and melatonin treatments on serotonin uptake and release from synaptosomes of rat hypothalamic regions

This study examined the effects induced by long-term pinealectomy, daily melatonin treatment to pinealectomized and intact rats, and a single melatonin injection on [14C]-serotonin (5-HT) uptake and release from synaptosomes obtained of hypothalamic regions. Pinealectomy inhibited the accumulation of labeled 5-HT by synaptosomes of the preoptic area-anterior hypothalamus (POA-AH), but it failed to alter the [K+]-evoked 5-HT release. Melatonin treatment for 10 consecutive days to pinealectomized rats restored 5-HT uptake in POA-AH, and also increased 5-HT release in medial and posterior hypothalamus. These results suggest that pineal melatonin plays a stimulatory role on the serotoninergic terminals of the hypothalamus. Moreover, when daily melatonin treatment was administered to intact rats a significant increase in 5-HT uptake activity by synaptosomes of all the hypothalamic regions was observed, but 5-HT release was unaffected. In contrast, a single melatonin injection induced a significant decrease in 5-HT release from synaptosomes of the POA-AH was observed. The results suggest the existence of a differential sensitivity in the mechanisms mediating melatonin actions on 5-HT uptake/release, which depends on the presence of the pineal gland in the animals and on the frequency of the treatments with the pineal hormone.

Effects of single doses and daily melatonin treatments on serotonin metabolism in rat brain regions

The acute effects of two doses (0.5 and 1 mg/kg) of melatonin on the levels of tryptophan, serotonin, and 5-hydroxyindoleacetic acid in several rat brain regions were studied. Tryptophan content in the brain regions was unchanged by the treatments. Melatonin at a dosage of 0.5 mg/kg increased medial hypothalamic serotonin levels at 60 and 90 min after the injection. However, the dose of 1 mg/kg increased the levels of this amine or its metabolite in the preoptic area-anterior hypothalamus, medial and posterior hypothalamus, amygdala, and midbrain. These results suggest a specific regional sensitivity to melatonin as well as a dose-dependent response. The stimulatory melatonin effect on the serotoninergic system was also observed after a daily treatment with this hormone (0.5 mg/kg, twice daily during 10 days) in both intact or pinealectomized rats. In intact rats, melatonin treatment increased the levels of 5-hydroxyindole-3-acetic acid in the preoptic area-anterior hypothalamus and medial hypothalamus, while in pinealectomized rats melatonin increased the serotonin content in the medial hypothalamic region. The data support the idea that melatonin has a selective action on serotonin metabolism in regions that contain serotoninergic terminals, especially at medial hypothalamic level.

Metacarpal cortical thickness by computed radiography in osteoporosis

Computed radiography was used to make radiogrammetric measurements of the second metacarpal in 240 women, 180 considered normal and 60 osteoporotic. These measurements had a coefficient of variation for the external diameter of 0.74% in normal women and 0.75% in osteoporotic women, and for the internal diameter of 2.4% and 2.03%, respectively. The group of women with osteoporosis was divided according to external diameter and internal diameter into a group with osteoporosis due to increased bone resorption (61.1%, normal external diameter and increased internal diameter), and osteoporosis due to deficient bone formation (26.1%, decreased external diameter and normal internal diameter). In the remaining subjects (12.8%), osteoporosis was attributed to both mechanisms. There was a significant linear regression between internal diameter and tartrate-resistant acid phosphatase concentration (p < 0.0001) in the group of increased bone resorption, which was absent (p = ns) in the group with deficient bone mass formation. No changes were observed in the size of the two groups. The low coefficient of variation of radiogrammetric measurements with computed radiography validate it as an accurate technique for bone mass studies. Moreover, it has the additional advantage of permitting determination of the proportion of women with osteoporosis due to increased bone resorption and/or deficient bone mass formation.

A fifty-year follow-up of ocular defects in congenital rubella: late ocular manifestations

Fifty patients born with congenital rubella in 1939-1945 were reviewed in 1967. In 1991 this cohort was again studied and their ophthalmic features are presented here. The presence of two new cataracts and one case of possible choroidal neovascularisation are again noted; apart from these three eyes, the group showed no evidence of other delayed manifestations of the congenital rubella syndrome. A review is given of the ocular complications of the congenital rubella syndrome, with particular emphasis on the late complications.

Arrest of human lung tumor xenograft growth in severe combined immunodeficient mice using doxorubicin encapsulated in sterically stabilized liposomes

Incorporation of polyethylene glycol-derivatized phospholipids into liposomes results in carriers that can enhance the therapeutic efficacy of encapsulated drugs by imparting the ability to evade the reticuloendothelial system and remain in the circulation for prolonged periods. In this study, doxorubicin encapsulated in these sterically stabilized liposomes (S-DOX) is shown to completely arrest the growth of human lung tumor xenografts in severe combined immunodeficient (scid) mice. Doxorubicin administered at equivalent doses as free drug or encapsulated into conventional liposomes was ineffective at completely arresting the growth of this human tumor, although a decrease in tumor growth rate compared to untreated controls was observed. Scid mice were found to be significantly more susceptible to the toxic effects of doxorubicin than were immunocompetent C.B-17 control mice, a characteristic that is likely to result from the deficit in DNA repair mechanisms previously identified in scid mice. However, doxorubicin toxicity in scid mice could be minimized while maintaining the antitumor activity of doxorubicin encapsulated in sterically stabilized liposomes by administering the drug in multiple weekly injections at low doses. This report provides the first evidence that antitumor drugs delivered in sterically stabilized liposomes are more effective at arresting the growth of human tumors than are conventional delivery systems. In addition, the scid mouse is presented as a viable model in which to study novel chemotherapeutic approaches to the treatment of human cancer.

Extravasation and transcytosis of liposomes in Kaposi's sarcoma-like dermal lesions of transgenic mice bearing the HIV tat gene

Transgenic mice bearing the HIV tat gene develop dermal lesions resembling a common malignant tumor in AIDS, Kaposi's sarcoma (KS). To evaluate the permeability characteristics of these lesions and the therapeutic potential of drug-carrying liposomes, we have studied the localization of sterically stabilized liposomes, which show long circulation time in blood and increased accumulation in tumors. Liposomes encapsulating colloidal gold were injected intravenously into transgenic mice bearing KS lesions, and tissues were processed 24 hours later for both electron microscopy and for light microscopy with silver enhancement. Liposomes and silver marker were detected predominantly in the dermis surrounding the early and mature KS lesions, which were characterized by a proliferation of fibroblast-like spindle cells and abnormal blood vessels close to the epidermis. The silver-enhanced gold marker often surrounded vascular channels and scattered erythrocytes. As determined by electron microscopy, some spindle cells and macrophages had ingested intact liposomes. Transendothelial transport of liposomes was observed both through open channels between endothelial cells and also through endothelial cells lining intact vessels. Both extravasation and transcytosis of liposomes through irregular endothelium were much higher in KS lesions than in the adjacent normal skin. The high accumulation of sterically stabilized liposomes in KS lesions and their intracellular uptake by some spindle cells enhances their potential as carriers of chemotherapeutic agents against this neoplasm.

Pharmacokinetics and therapeutics of sterically stabilized liposomes in mice bearing C-26 colon carcinoma

Three different liposome types were compared for blood clearance and tissue uptake in mice bearing C-26 colon carcinoma growing either s.c. or in liver. Therapeutic experiments were performed with the liposome preparation showing the highest tumor uptake. Liposomes were composed of solid-phase phosphatidylcholine, either distearoyl phosphatidylcholine or hydrogenated soy phosphatidylcholine, and cholesterol at a 2:1 molar ratio. These liposomes were compared with similar but sterically stabilized liposomes (SL) which, in addition, contained either GM1 ganglioside or phosphatidylethanolamine derivatized with poly(ethylene glycol). Pharmacokinetic analysis of drug disposition was based on the areas under the curve for liposome-entrapped 67Ga uptake per gram of tissue up to 96 h following i.v. injection. The highest tissue area under the curve values with both liposome types were obtained in spleen, liver, and tumor. However, the sterically stabilized liposomes gave an area under the curve value 2-3-fold higher in the s.c. tumor and about 2-fold lower in liver and spleen. The therapeutic efficacy of doxorubicin (DOX) and epirubicin (EPI) encapsulated in poly(ethylene glycol)-derivatized phosphatidylethanolamine-containing liposomes was compared with that of free drug at two doses, 6 and 9 (or 10) mg/kg animal weight. Liposomes containing drug were injected either as a single dose, at different times following tumor implantation, or as three weekly doses starting 10 days after implantation. When injected as a single dose, liposome-encapsulated DOX had the maximal effect on tumor growth when injected 6 to 9 days after tumor implantation. When injected as three weekly doses, with treatment starting with a delay of 10 days, tumors which had grown to a size of approximately 0.05-0.1 cm3 regressed in groups of animals treated with either liposome-encapsulated drug (SL-DOX or SL-EPI) but continued to grow unabated in untreated mice and in mice receiving either of the free drugs. Survival of tumor-bearing animals treated with either SL-EPI or SL-DOX was significantly prolonged. Animals receiving saline, EPI, or DOX survived a mean of 50, 62, and 49 days, respectively, following tumor implantation. Eight of nine and nine of 10 animals receiving 6 and 9 mg/kg SL-EPI, respectively, survived to 120 days. Ten of 10 animals in both groups receiving 6 and 9 mg/kg SL-DOX survived to 120 days. None of the surviving animals in the SL-EPI and SL-DOX group showed any histological evidence of tumor at the conclusion of the experiment (120 days).(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacokinetics and antitumor activity of epirubicin encapsulated in long-circulating liposomes incorporating a polyethylene glycol-derivatized phospholipid

The antitumor activity of epirubicin (EPI) entrapped in long circulating "Stealth" liposomes containing a polyethylene glycol-derivatized phospholipid (S-EPI) was compared to epirubicin encapsulated in a conventional liposome formulation (L-EPI) and free epirubicin (F-EPI) against mouse colon 26 tumor in vivo. Pharmacokinetics of S-EPI and F-EPI were also compared in rats. F-EPI was distributed to tissues within minutes of injection. In contrast, when administered in the S-EPI formulation, the distribution half-life of the drug was over 22 hr. S-EPI also exhibited a reduced clearance compared to F-EPI, from 111 to less than 1.0 ml/hr. S-EPI inhibited tumor growth more effectively than F-EPI or L-EPI by causing tumors to regress and increasing survival of mice. There were 9/10 (S-EPI) compared to 0/10 (F-EPI) 120-day survivors when treatment was started 3 days after tumor implant. When treatment was delayed for 10 days, tumors, which had reached approx. 0.1-0.3 cm3 in volume, regressed in 8/10 animals receiving S-EPI, whereas in all animals treated with F-EPI the tumors progressed. L-EPI was no more effective therapeutically than F-EPI in this model. The maximum tolerated dose of S-EPI was higher than that of F-EPI. The enhanced therapeutic efficacy of S-EPI is probably related to the extended circulation time of the formulation and its accumulation in tumors.

Versatility in lipid compositions showing prolonged circulation with sterically stabilized liposomes

Efforts to overcome rapid uptake of liposomes by cells of the mononuclear phagocytic system (MPS) have identified that lipids derivatized with the hydrophilic polymer poly(ethylene glycol) (PEG) have many advantages. The structure-function relationship of PEG-derivatized phosphatidylethanolamine (PEG-PE) has been examined by studies of blood lifetime and tissue distribution in both mice and rats. Liposomes composed of phosphatidylcholine (PC), cholesterol, and 7.5 mol% of PEG-PE show prolonged circulation and reduced MPS uptake when the PEG has a molecular weight in the range of 1000 to 5000. Up to 35% of the injected dose remains in the blood and less than 10% is taken up by the MPS (liver plus spleen) after 24 h in the best cases as compared to 1% and 40%, respectively, for liposomes without PEG-PE. Prolonged circulation with PEG-PE is independent of cholesterol, degree of saturation in either the PC or the PE lipid anchor, lipid dose, or addition of other negatively charged lipids, phosphatidylglycerol or cholesterol sulfate. This versatility in lipid composition and dose without alteration of blood lifetime or tissue distribution is essential for controlling drug dosage and release properties in a liposome-based therapeutic agent.

Sterically stabilized liposomes. Reduction in electrophoretic mobility but not electrostatic surface potential

The electrophoretic mobility of liposomes containing a negatively charged derivative of phosphatidylethanolamine with a large headgroup composed of the hydrophilic polymer polyethylene glycol (PEG-PE) was determined by Doppler electrophoretic light scattering. The results show that this method is improved by the use of measurements at multiple angles to eliminate artifacts and that very small mobilities can be measured. The electrophoretic mobility of liposomes with 5 to 10 mol% PEG-PE is approximately -0.5 mu ms-1/Vcm-1 regardless of PEG-PE content compared with approximately -2 mu ms-1/Vcm-1 for similar liposomes but containing 7.5% phosphatidylglycerol (PG) instead of PEG-PE. Measurements of surface potential by distribution of an anionic fluorescent probe show that the PEG-PE imparts a negative charge identical to that by PG, consistent with the expectation of similar locations of the ionized phosphate responsible for the charge. The reduced mobility imparted by the surface bound PEG is attributed to a mechanism similar to that described for colloidal steric stabilization: hydrodynamic drag moves the hydrodynamic plane of shear, or the hydrodynamic radius, away from the charge-bearing plane, that of the phosphate moities. An extended length of approximately 50 A for the 2,000 molecular weight PEG is estimated from the reduction in electrophoretic mobility.

Prolonged systemic delivery of peptide drugs by long-circulating liposomes: illustration with vasopressin in the Brattleboro rat

The value of novel systemically long-circulating liposomes to prolong the duration of an antidiuretic hormone, arg8-vasopressin (VP), was investigated as a representative of low molecular weight peptides with rapid clearance. Cholesterol content was found to have a controlling effect on VP release in serum. Three types of liposomes were selected for urine production measurements in VP deficient Brattleboro rats. One contained phosphatidylserine (PS), which was rapidly cleared from the circulation. In the other two liposomes, the PS component was replaced by either phosphatidylglycerol or a novel phospholipid derivatized with polyethylene glycol (PEG); both showing prolonged circulation. Free VP (up to 8 micrograms/kg) gave reduced urine production for less than 24 hr. The PG formulation exhibited a dose-dependent prolonged duration of bioactivity of up to 4 days. Substitution of PEG-PE resulted in a 2-day delay followed by a prolonged duration of bioactivity for over 4 days. The duration of the prolonged bioactivity was not dose dependent but the amplitude was. This is attributed to VP release from liposomes which have distributed intact to another compartment without having been taken up by the RES. By balancing liposome circulation time, release rate, and dose, long-circulating liposomes can be applied to prolong the biological activity of a therapeutic peptide.

Sterically stabilized liposomes: a hypothesis on the molecular origin of the extended circulation times

Therapeutic applications of intravenously injected liposomes have been limited by their rapid clearance from the bloodstream and their uptake by the macrophage cells of the liver and spleen (RES). Recently, however, liposomes which substantially evade the rapid uptake by the RES have been introduced. Since these liposomes exhibit dramatically different pharmacokinetics and biodistribution, new therapeutic opportunities have appeared. These include enhanced efficacy of antineoplastic agents against tumors, sites of inflammation, and targeting ligand-coupled liposomes to extravascular targets. Despite extensive experimental work, the mechanism underlying the ability of liposomes to avoid the rapid uptake by the RES is still not fully understood. Our approach is an alternative to seeking the answers in complex differential interactions of liposomes with various components of blood. We believe that the effect can be easily explained, at least in qualitative terms, by the fundamental principles of colloid stability. In this communication, we propose that steric stabilization of liposomes is responsible for their prolonged circulation times. We propose that stabilization results from local surface concentration of highly hydrated groups that sterically inhibit both electrostatic and hydrophobic interactions of a variety of blood components at the liposome surface.

Assessment of vision in infants and children

An understanding of vision development is important in the assessment of visual problems. The authors look at this factor and outline testing procedures useful in the assessment of vision in the paediatric patient.

Intraocular lacrimal gland choristoma

There have been nine previously reported cases of intraocular lacrimal gland choristoma. This case report is of an infant with an intraocular lacrimal gland choristoma which was managed conservatively for a 19-month period until the onset of glaucoma. Tumour biopsy was initially performed because until this time the tumour's behaviour suggested it was not malignant. The latter was confirmed on biopsy, however hypotony resulted following the surgical intervention.

The impact of discussion of non-medical problems in the physician's office

To determine the impact of discussion of non-medical problems with the physician, patients with at least one chronic illness who were taking medication were interviewed in their family doctor's office. Of 149 patients interviewed, 90.6% reported at least one non-medical problem. Half (51%) of those patients with a problem had discussed it with their doctor. More than half (55%) of those patients discussing a problem reported that the discussion was helpful. Patient compliance and satisfaction were positively associated with 'helpful' discussion, but not with discussion per se. In particular, the two aspects of doctor-patient communication which were significantly associated with feeling helped were: 'Doctor tells me all I want to know about my illness' and 'Doctor gives me a chance to say what is really on my mind'. Both factors reflect care which is oriented to patient concerns. The study results provide support for a patient-centred approach to care.

Epilogue. Establishment of the Center for Chronic Disease Prevention and Health Promotion

The establishment of the Center for Chronic Disease Prevention and Health Promotion (CCDPHP) at the Centers for Disease Control (CDC) following the Conferences on the State of the Art in Quality Control Measures for Diagnostic Cytology Laboratories is briefly discussed. The CCDPHP is expected to play a major role in the CDC's cancer control program, including participation in establishing effective screening programs and assuring the quality of such methodologies as the Papanicolaou test and mammography.

Measuring screening skills in gynecologic cytology. Results of voluntary self-assessment

When the Clinical Laboratory Improvement Act (CLIA) was passed in 1967, the Centers for Disease Control (CDC) became interested in evaluating screening performance in cytodiagnosis. Finding no validated performance measurement methods that could be used on a national scale, the CDC initiated a program of sequential investigations to develop information that would describe the state of the art in microscopic performance in gynecologic cytopathology. The first of these experiments developed a method, the Self-Assessment Workshop, to measure performance at the microscope by using sets of glass slides. This paper describes the method, its validation process and participant performance over a 15-year period. Study results indicated that cytotechnologists and pathologists tended to correctly identify specimens (slides) in the negative and benign reaction categories in up to 95% of responses, but on slides of dysplasia they made 12% of their calls too low. Carcinomas in situ and invasive squamous cancers were undercalled in only about 5% of responses, but endometrial adenocarcinomas and other rare malignancies were undercalled in as much as 20%. The self-assessment technique is a practical, useful tool for identifying cytology personnel with serious deficiencies in cell location/identification skills and is well accepted by cytotechnologists and pathologists. However its limitations should be kept in mind: screening results from this simulated test should not be extrapolated to routine work performance; the screening time limit of five minutes per slide may adversely affect performance; and, finally, these results may reflect state-of-the-art performance only in voluntary, not mandatory, settings.

Large liposome agglutination technique for the serological detection of syphilis

In response to tissue invasion by Treponema pallidum, an antibody complex, called reagin, appears in the serum of the syphilitic patients. Reagin has the ability to combine with cardiolipin, therefore, cardiolipin has traditionally been used as the antigen in different test configurations for the serological detection of syphilis: the VDRL (Venereal Disease Research Laboratory) flocculation test and the RPR (rapid plasma reagin) test. Here we introduce a liposome preparation composed of cardiolipin, lecithin and cholesterol and containing a colored dye which upon mixing with syphilitic serum on a slide or a plastic card results in clearly visible liposome agglutination. We show that the liposomes in the size range of 1-10 micron are essential for proper sensitivity. The liposomes are colored with either a water-soluble dye entrapped in the aqueous space of liposomes or a lipophilic dye embedded in the membrane. By virtue of the liposome size and coloration the agglutination pattern is easily visible within 3-5 min without the use of a mechanical rotator. The approach described here can be extended to the detection of other antibodies and polyvalent antigens.

The development and application of protein-liposome conjugation techniques

Numerous techniques have been developed over the past 10 years for the conjugation of proteins to liposomes. Early procedures involved coupling with reagents such as glutaraldehyde or EDCI. Subsequently, more sophisticated approaches involving selective bifunctional coupling agents have been developed. These later procedures are also much more efficient for coupling in aqueous media. The techniques of coupling have become more rigorous because investigators have recognized the inherent problems of producing, purifying and characterizing protein conjugated liposomes. Protein-liposome coupling techniques were developed mainly for targeted drug delivery. The attachment of specific antibodies to the surface of the liposomes makes them able to bind to cells and to subsequently be internalised by the cells. Protein conjugated liposomes have also been used for various immunochemical and diagnostic purposes. These include the binding of labelled liposomes to cells and the agglutination of cells or latex particles by protein conjugated liposomes.

Concurrent pineoblastoma and unilateral retinoblastoma: a forme fruste of trilateral retinoblastoma?

A 10-month-old boy who presented with strabismus and symptoms of intracranial hypertension was found to have a pineoblastoma and a unilateral ocular retinoblastoma. Despite enucleation of the eye, subtotal removal of the pineoblastoma, and craniospinal axis irradiation, the patient died 6 months later from disseminated intracranial neoplasm. As there was no clinical evidence of bilateral retinoblastoma, this case may represent a forme fruste of the trilateral retinoblastoma complex. The clinicopathological features of this unusual syndrome are reviewed.

Association of ganglioside-protein conjugates into cell and Sendai virus. Requirement for the HN subunit in viral fusion

A method is described for preparing a covalent conjugate of proteins, in particular antibodies and their fragments, with gangliosides in the micellar form. The protein-ganglioside conjugate is associated with ganglioside micelles and can be separated from free protein by molecular sieve chromatography. Conjugates can irreversibly transfer from the micelle to a cell membrane of choice, and the protein portion be identified as a new surface antigen. The successful application of this methodology has been demonstrated with three biological systems. Rabbit IgG-ganglioside conjugate has been transferred to human or sheep erythrocytes, which have been hemagglutinated with goat anti-rabbit IgG. Erythrocytes modified with ganglioside-anti-H2Kk have been shown to adhere to monolayers of L929 mouse fibroblasts which express H2Kk-antigen. Mouse monoclonal anti-glycophorin ganglioside conjugate can associate with Sendai virus and confer upon the virus the ability to agglutinate and hemolyse desialylated human erythrocytes. Using the anti-glycophorin conjugate, we demonstrated that the HN subunit, which is normally responsible for viral binding, appears also to be essential for fusion activity, because its destruction eliminates hemolysis and fusion, but not agglutination, by the conjugate-modified virus.

Irreversible coupling of immunoglobulin fragments to preformed vesicles. An improved method for liposome targeting

Rabbit Fab' antibody fragments were covalently couple to preformed large unilamellar vesicles using a new sulfhydryl-reactive phospholipid derivative N-[4-(p-maleimidophenyl)butyryl]phosphatidylethanolamine (MPB-PE). A highly efficient reaction between the sulfhydryl group on each Fab' fragment and the maleimide moiety of MPB-PE molecules incorporated at a low concentration in vesicle bilayers led to the formation of a highly stable Fab'-vesicle linkage. Coupling ratios in excess of 250 micrograms of Fab'/mumol of vesicle phospholipid were reproduciably obtained without vesicle aggregation. Bound Fab' fragments did not elute from vesicles in serum or in the presence of reducing agents (dithiothreitol or mercaptoethanol). Vesicles bearing Fab' fragments raised against specific human erythrocyte surface determinants bound selectively to human erythrocytes under physiological conditions (isotonic medium containing 50% human serum, pH 7.4) with minimal leakage of vesicle contents. Advantages of the present coupling method are discussed in relationship to our effects to optimize the properties of liposomes as a carrier system.

Immunospecific targeting of liposomes to cells: a novel and efficient method for covalent attachment of Fab' fragments via disulfide bonds

An efficient method for covalently cross-linking 50K Fab' antibody fragments to the surface of lipid vesicles is reported. Coupling up to 600 microgram of Fab'/mumol of phospholipid (about 6000 Fab' molecules per 0.2-micrometer vesicle) is achieved via a disulfide interchange reaction between the thiol group exposed on each Fab' fragment and a pyridyldithio-derivative of phosphatidylethanolamine present in low concentration in the membranes of preformed large unilamellar vesicles. The coupling reaction is efficient, proceeds rapidly under mild conditions, and yields well-defined products. Each vesicle-linked Fab' fragment retains its original antigenic specificity and full capacity to bind antigen. We have used Fab' fragments, coupled to vesicles by this method, to achieve immunospecific targeting of liposomes to cells in vitro. Vesicles bearing antihuman erythrocyte Fab' fragments bind quantitatively to human erythrocytes (at multiplicities up to 5000 0.2-micrometer vesicles per cell) while essentially no binding is observed to sheep or ox red blood cells. Vesicle-cell binding is stable over a pH range from 6 to 8 and is virtually unaffected by the presence of human serum (50%). Cell-bound vesicles retain their aqueous contents and can be eluted intact from cells by treatment with reducing agents (dithiothreitol or mercaptoethanol) at alkaline pH.

Timolol maleate. A report from the Glaucoma Clinic, Sydney Eye Hospital

Timolol Maleate was successful in controlling the intraocular pressure in 59% of eyes with glaucoma. The addition of Pilocarpine or Epinephrine increased the total of eyes controlled to 86%.

Management of persistent filtering cicatrix following cataract extraction

We used a safe and simple surgical technique in the management of persistent filtering cicatrices after cataract extraction. The edematous, friable filtering cicatrix was excised entirely and a healthy fornix-based conjunctival flap was sutured over the fistula. Invariably, the fistula was very small, usually only large enough to admit a 27-gauge needle. Of the 27 eyes treated with this technique, there were two failures, but no other complications.

Lipid vesicle-cell interactions. II. Induction of cell fusion

The ability of lipid vesicles of simple composition (lecithin, lysolecithin, and stearylamine) to induce cells of various types to fuse has been investigated. One in every three or four cells in monolayer cultures can be induced to fuse with a vesicle dose of about 100 per cell. At such dosages and for exposures of 15 min to 1 h, vesicles have essentially no effect on cell viability. Under anaerobic conditions, these cells lyse rather than fuse. Avian erythrocytes are readily fused with lipid vesicles in the presence of dextran. Fusion indices increase linearly with the zeta potential of the vesicles (increasing stearylamine content), indicating that contact between vesicle and cell membrane is required. Fusion indices increase sublinearly with increasing lysolecithin content. Divalent cations increase fusion indices at high vesicle doses. The data presented are consistent with the hypothesis that cell fusion occurs via simultaneous fusion of a vesicle with two adhering cell membranes.

Lipid vesicle-cell interactions. I. Hemagglutination and hemolysis

The interaction of lipid vesicles (liposomes) of several different compositions with erythrocytes has been investigated. Lecithin liposomes, rendered positively charged with stearylamine, exhibit potent hemagglutination activity in media containing low concentrations of electrolytes. The hemagglutination titer is found to be a linear function of the zeta potential of the lipid vesicles. Hemagglutination is reduced when the surface potential of the cells is made more positive by pH adjustment or enzyme treatment. Similarly, hemagglutination is reduced by increasing concentrations of electrolytes. Hemagglutination is examined theoretically and is shown to be consistent with vesicle-cell interactions that are due to only electrostatic forces. Vesicles containing lysolecithin in addition to lecithin and stearylamine cause lysis of erythrocytes, provided the lipids of the vesicles are above the crystal-liquid crystal phase transition temperature. In addition, hemolysis requires close juxtaposition of the vesicle to the cell membrane; vesicles precoated with antibodies exhibit severely diminished hemolytic activities, only a small fraction of which can be attributed to a reduction in hemagglutination titer. Evidence is presented indicating that a single vesicle is sufficient to lyse one cell. With regard to hemagglutination and hemolysis, lipid vesicles of simple composition mimic paramyxoviruses such as Sendai virus.

Lipid vesicle-cell interactions. III. Introduction of a new antigenic determinant into erythrocyte membranes

The introduction of a new antigenic determinant, 2,4-dinitrophenyl-aminocaproyl-phosphatidylethanolamine (DNP-Cap-PE), into the surface membranes of intact human erythrocytes is described. Fresh cells were incubated in the presence of liposomes composed of 10% DNP-Cap-PE, 5% stearylamine, 20% lysolecithin, and 65% lecithin. Such liposome-treated erythrocytes are shown to be susceptible to immune lysis by anti-DNP serum in the presence of complement. Uptake of DNP-Cap-PE by erythrocyte membranes is also demonstrated by immunofluorescence using indirect staining with rabbit anti-DNP serum followed by fluroescein-conjugated goat anti-rabbit IgG and by electron microscopy using ferritin-conjugated antibody. Antigen uptake did not occur at low temperatures or from vesicles lacking lysolecithin and stearylamine. Fluorescence microscopy shows that the antigen-antibody complexes are free to diffuse over the cell surface, eventually coalescing into a single area on the cell membrane. Electron microscopy suggests that a substantial proportion of the lipid antigen is incorporated by fusion of vesicles with the cell membrane. There are indications that vesicle treatment causes a small proportion of cells to invaginate.

Phospholipid exchange between bilayer membrane vesicles

The turbidity of lipid vesicles, freshly prepared by sonicating purified dimyristoyllecithin (DML) in dilute KCl solutions, was measured as a function of time at various temperatures. A sharp maximum in the rate of increase of turbidity is found just above the crystal:liquid-crystal phase transition temperature (Tm). The initial rate of turbidity increase is first order with respect to DML concentration. Electron and light microscopy reveal large vesicles which are not present before incubation or after incubation at temperatures far from the Tm. When temperature, rather than time, is the independent variable, a sharp drop in turbidity is seen at the Tm. The magnitude of this drop and the temperature at which it occurs were used to measure the rate of lipid transfer between vesicles composed of different lipids. A mixture of DML vesicles and dipalmitoyllecithin (DPL) vesicles exhibits sharp drops in turbidity at 24 and 41 degrees, the corresponding Tm's. With time, the magnitude of the transition at 24 degrees decreases while that which was originally at 41 degrees moves to lower temperatures and increases in magnitude. At equilibrium there is a single transition at 32.5 degrees characteristic of vesicles composed of equimolar DPL and DML. The rate at which equilibrium is approached increases at around 24 degrees and again around 41 degrees. These observations indicate that vesicles are in equilibrium with monomolecular lipid, the concentration of the latter being higher the shorter the lipid acyl group or the smaller the vesicle. DML molecules are therefore lost from small vesicles to large vesicles (DML system) or lost from DML vesicles to DML-DPL vesicles (mixed system). When DML vesicles containing a few percent brain gangliosides were studied, different behavior was observed; the initial rate of increase of turbidity becomes second order in lipid concentration, and the rate constant increases with increasing concentrations of KCl. The kinetic order, coupled with the fact that electrolyte reduces intervesicle electrostatic repulsion, argues that in this situation the mechanism of vesicle growth requires vesicle collision.

Epidermal neoplasms with epidermolysis bullosa dystrophica with the first report of carcinoma with the acquired type

Carcinoma, usually always squamous cell carcinoma, is one of the most serious complications in epidermolysis bullosa dystrophica. It can occur on the skin, mucous membranes, the esophagus and possibly the upper part of the bronchial tree. We are reporting on four new patients; one, the youngest to be so reported, one with a definite autosomal dominant inheritance and one with a chronic acquired dystrophica epidermolysis bullosa. Most cases have an autosomal recessive inheritance, but the disorder is probably more hetereogeneous in its inheritance than has been reported. Studies of the collagen indicate a disturbance, but present studies indicate the defect to be more a cellular defect in the fibroblast yet undetermined. The carcinomas, usually multiple, appear to arise on scarred tissue and to metastasize rapidly with death.