Chemosensitization of tumors via simultaneous delivery of STAT3 inhibitor and doxorubicin through HPMA copolymer-based nanotherapeutics with pH-sensitive activation.

We synthesized three novel STAT3 inhibitors (S3iD1-S3iD3) possessing oxoheptanoic residue enabling linkage to HPMA copolymer carrier via a pH-sensitive hydrazone bond. HPMA copolymer conjugates bearing doxorubicin (Dox) and our STAT3 inhibitors were synthesized to evaluate the anticancer effect of Dox and STAT3 inhibitor co-delivery into tumors. S3iD1-3 and their copolymer-bound counterparts (P-S3iD1-P-S3iD3) showed considerable in vitro cytostatic activities in five mouse and human cancer cell lines with IC50 ~0.6-7.9 µM and 0.7-10.9 µM, respectively. S3iD2 and S3iD3 were confirmed to inhibit the STAT3 signaling pathway. The combination of HPMA copolymer-bound Dox (P-Dox) and P-S3iD3 at the dosage showing negligible toxicity demonstrated significant antitumor activity in B16F10 melanoma-bearing mice and completely cured 2 out of 15 mice. P-Dox alone had a significantly lower therapeutic activity with no completely cured mice. Thus, polymer conjugates bearing STAT3 inhibitors may be used for the chemosensitization of chemorefractory tumors.

Polymer nitric oxide donors potentiate the treatment of experimental solid tumours by increasing drug accumulation in the tumour tissue.

The delivery of nitric oxide (NO) specifically to solid tumours was explored in this study as a strategy to augment the passive accumulation of nanomedicines in tumours induced by the Enhanced Permeability and Retention (EPR) effect. An increase in accumulation was achieved by the binding of the chemical precursor of NO, based on an organic nitrate, to a water-soluble synthetic polymer drug carrier. Four structurally different N-(2-hydroxypropyl)methacrylamide (HPMA)-based polymer NO donors were synthesized. Depending on their chemical structure, two of these donors were hydrolytically stable, while two rapidly released the parent nitrate under acidic conditions, mimicking the intracellular environment. The polymer NO donors were shown to overcome the drawbacks related to low-molecular-weight NO releasing compounds, namely systemic toxicity, lack of site specificity, and fast blood clearance. The NO donors showed intracellular NO release upon incubation with tumour cells. In vivo, they potentiated the EPR effect, resulting in an increased accumulation of polymer-bound cytotoxic drug doxorubicin (Dox) in EL4 T-cell lymphoma inoculated in mice. This led to a better therapeutic outcome in the treatment of lymphoma with the high-molecular-weight polymer conjugates carrying Dox but not in the treatment with the free Dox. The localized augmentation of the EPR effect via the tumour-specific NO delivery system can be viewed as a promising strategy to potentiate polymer-based tumour therapy without increasing systemic toxicity.

NUMERICAL EVALUATION OF SCAR AFTER BREAST RECONSTRUCTION WITH ABDOMINAL ADVANCEMENT FLAP.

BACKGROUND: The treatment of breast cancer has developed a lot during the last decade, nevertheless it still remains a considerable social and economical problem all over the world. The choice of the surgical procedure depends on a patients protocol and the surgeons preferences. The aim of this study is to evaluate the stress on the scar after breast reconstruction. METHODS: Mathematical modeling of the sutured skin flap used for breast implant placement was divided into the following two steps. At first, material model of the selected silicone implant was identified. Afterwards, the mathematical model of the breast and implant was performed. RESULTS: Maximal geometrical deviation for anatomical and round implant is placed on the lower surface of the breast and upper surface of the breast, while in the area of lateral geometry and the area around the nipple the agreement reaches very high level. The maximal tension is located in two median stitches. The maximal force reaches 0.025 N. The Cauchy stress equivalent is located around the nipple and reaches the value of 380 kPa. CONCLUSION: From our results it can be seen, that the anatomical and round breast implants do not result in the same stress on the scar. The maximal value difference reaches 13.4% between stress values for these two breast implants and the round implant results in higher loaded scar compared to the anatomical implant.

Synthesis of poly[N-(2-hydroxypropyl)methacrylamide] conjugates of inhibitors of the ABC transporter that overcome multidrug resistance in doxorubicin-resistant P388 cells in vitro.

The effects of novel polymeric therapeutics based on water-soluble N-(2-hydroxypropyl)methacrylamide copolymers (P(HPMA)) bearing the anticancer drug doxorubicin (Dox), an inhibitor of ABC transporters, or both, on the viability and the proliferation of the murine monocytic leukemia cell line P388 (parental cell line) and its doxorubicin-resistant subline P388/MDR were studied in vitro. The inhibitor derivatives 5-methyl-4-oxohexanoyl reversin 121 (MeOHe-R121) and 5-methyl-4-oxohexanoyl ritonavir ester (MeOHe-RIT), showing the highest inhibitory activities, were conjugated to the P(HPMA) via the biodegradable pH-sensitive hydrazone bond, and the ability of these conjugates to block the ATP driven P-glycoprotein (P-gp) efflux pump was tested. The P(HPMA) conjugate P-Ahx-NH-N═MeOHe-R121 showed a dose-dependent increase in the ability to sensitize the P388/MDR cells to Dox from 1.5 to 24 µM, and achieved an approximately 50-fold increase in sensitization at 24 µM. The P(HPMA) conjugate P-Ahx-NH-N═MeOHe-RIT showed moderate activity at 6 µM (∼10 times higher sensitization) and increased sensitization by 50-fold at 12 µM. The cytostatic activity of the P(HPMA) conjugate P-Ahx-NH-N═MeOHe-R121(Dox) containing Dox and the P-gp inhibitor MeOHe-R121, both bound via hydrazone bonds to the P(HPMA) carrier, was almost 30 times higher than that of the conjugate P-Ahx-NH-N═Dox toward the P388/MDR cells in vitro. A similar result was observed for P-Ahx-NH-N═MeOHe-RIT(Dox), which exhibited almost 10 times higher cytostatic activity than P-Ahx-NH-N═Dox.

Synergistic action of doxorubicin bound to the polymeric carrier based on N-(2-hydroxypropyl)methacrylamide copolymers through an amide or hydrazone bond.

The cytostatic effects of polymeric conjugates based on N-(2-hydroxypropyl)methacrylamide copolymers (PHPMA) and containing doxorubicin bound through amide and hydrazone bonds (mixed conjugates) were compared with the cytostatic effects of monoconjugates containing drug bound through an amide or hydrazone bond. One group of mixed conjugates was formed from two comonomers containing doxorubicin bound to the methacryloyl group through a spacer and an amide (DOX(AM)) or hydrazone (DOX(HYD)) bond via copolymerization with HPMA. A second group of mixed conjugates was formed from two different interconnected HPMA copolymers, one containing DOX(AM) and the other DOX(HYD), forming a high-molecular-weight branched structure. The third mixed polymeric system was a simple mixture of monoconjugates DOX(AM)-PHPMA and DOX(HYD)-PHPMA. Simultaneous treatment with all mixed forms of the polymeric derivatives of doxorubicin significantly increased antitumor efficacy after application of monoconjugates, suggesting a synergizing effect that could be used in designing new doxorubicin-containing therapeutic systems.

Induction of systemic antitumour resistance with targeted polymers.

Conjugates based on N-(2-hydroxypropyl)methacrylamide (HPMA) represent a new generation of antibody-targeted polymeric anticancer drugs with both cytotoxic and immunoprotecting/immunomobilizing activity. 20-90% of mice that are cured of EL4 mouse T-cell lymphoma, BCL1 mouse B-cell leukaemia and 38C13 mouse B-cell lymphoma by injection of doxorubicin-HPMA conjugate develop a long-lasting memory and systemic antitumour resistance. It is suggested that the main activity of the polymeric drug, directly after application is - due to the high level of the drug - of cytotoxic and cytostatic nature. Thereafter, long-term conjugates persist at low concentration in the circulation, which are capable of mobilizing the defence mechanisms of the host. Until now, seven patients with generalized carcinoma were treated with doxorubicin-HPMA-human-Ig conjugate. Disease stabilization, lasting from 6 to more than 18 months, was recorded.

HPMA copolymers containing doxorubicin bound by a proteolytically or hydrolytically cleavable bond: comparison of biological properties in vitro.

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer carrier containing the anticancer drug doxorubicin bound either by a proteolytically degradable bond (non-targeted PK1 or targeted with alpha-CD71 mAb) or by a hydrolytically degradable bond were synthesised and tested in vivo for various biological properties. Mouse 38C13 B-cell lympoma was used as a well established and defined cell line for this study. 38C13 cells are sensitive to free doxorubicin and IC50 was very low, about 0.014 microM. PK1 showed a strongly decreased cytostatic effect, IC50 being 12.6 microM. alpha-CD71 targeted conjugate, which can be considered as an antibody-targeted form of PK1, had IC50 0.358 microM. HPMA copolymer with doxorubicin bound via a hydrolytically sensitive bond (HYD conjugate) showed a high cytostatic effect with IC50 about 0.052 microM. We demonstrated that HYD conjugate inhibited DNA synthesis and induced p21(Waf1/Cip1) protein expression (p21(Waf1/Cip1) is cyclin-dependent kinase inhibitor which blocks cell cycle progression) as quickly as free doxorubicin, whereas PK1 acted much more slowly. Similarly, apoptosis induction measured by Annexin V binding and Caspase 3 activity was detected later after incubation of cells with PK1 or alpha-CD71 targeted conjugate. Apoptosis was manifested by elevation of bax and bad mRNA levels, which was much more rapid and intense in the case of free doxorubicin and HYD conjugate. Expression of antiapoptotic genes as well as cyclin-dependent kinases was surprisingly not affected.

HPMA copolymer-bound doxorubicin targeted to tumor-specific antigen of BCL1 mouse B cell leukemia.

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer carrier containing the anticancer drug doxorubicin and targeted with B1 monoclonal antibody (mAb) to BCL1 leukemia cells was synthesised and tested in vitro and in vivo. BCL1 leukemia growing in syngenic Balb/c mice was selected as a tumor model system. B1 mAb recognising the idiotype of surface IgM on BCL1 cells was used as a targeting moiety. Both B1 mAb and doxorubicin were conjugated to HPMA copolymer carrier by aminolysis through a tetrapeptidic Gly-Phe(D,L)-Leu-Gly spacer to ensure the intracellular delivery and controlled release of the drug. B1 mAb-targeted conjugate was shown to possess strictly tumor-specific binding capacity to target BCL1 cells in vitro. A similar conjugate, but containing human nonspecific Ig (HuIg) instead of B1 mAb, failed to bind to BCL1 cells. In vitro, B1 mAb-targeted conjugate demonstrated 40-fold higher cytotoxic effect than nontargeted or human nonspecific Ig-containing HPMA copolymer-bound doxorubicin. Conjugate targeted with B1 mAb was also shown to bind to target BCL1 cells in vivo. B1 mAb-targeted conjugate was shown to be more efficient in the treatment of established BCL1 leukemia than free doxorubicin, nontargeted and human nonspecific Ig-containing conjugate. Antibody-targeted polymeric drugs are thus promising conjugates for cancer treatment.

In vitro and in vivo effect of HPMA copolymer-bound doxorubicin targeted to transferrin receptor of B-cell lymphoma 38C13.

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymers containing the anticancer agent doxorubicin and targeted to the transferrin receptor either with anti-mouse CD71 monoclonal antibody (mAb) or with transferrin were synthesized to evaluate their binding and anti-proliferative activity in vitro and anti-tumor potential against 38C13 B-cell lymphoma in vivo. Both the doxorubicin and the targeting moieties were bound to HPMA copolymer chain by aminolysis via a Gly-Phe(D,L)-Leu-Gly spacer to ensure controlled intracellular release of the conjugated drug. We demonstrated that HPMA copolymer-bound doxorubicin targeted to the transferrin receptor with anti-mouse CD71 mAb strongly retards tumor growth, prolongs the survival and completely cures three out of nine experimental mice with established 38C13 tumors. The conjugate targeted with transferrin was less effective in vitro as well as in vivo. It completely cured only one out of seven experimental mice. Free or non-targeted HPMA copolymer-bound doxorubicin showed only a mild anti-tumor effect within the therapeutic schedule used. In vitro, HPMA copolymer-bound doxorubicin targeted with anti-mouse CD71 mAb shows approximately 4-fold higher cytotoxic effect than HPMA copolymer-bound doxorubicin targeted with transferin and 9-fold higher cytotoxic effect than non-targeted HPMA copolymer-bound doxorubicin.

Acquired and specific immunological mechanisms co-responsible for efficacy of polymer-bound drugs.

We present data providing new evidence that poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA)-bound drugs, unlike free drugs, have both cytostatic and immunomobilizing activity (CIA). Immediately after injection, due to the high level of the drug, the main activity of the polymeric conjugate is cytotoxic and cytostatic. Later on, long-term circulating PHPMA-bound drug, at concentrations lower than its minimal inhibitory levels, mobilizes the defense mechanisms of the host. Cytotoxic and cytostatic effects of drug-PHPMA were repeatedly confirmed. The following data support the concept of the immunomobilizing activity of the N-(2-hydroxypropyl)methacrylamide (HPMA) conjugates: (a) pre-treatment with free drugs (doxorubicin, cyclosporin A) accelerates the appearance of EL4 mouse T-cell lymphoma while a similar pre-treatment with doxorubicin-PHPMA induces limited but definitive mobilization of the host's defense mechanisms; (b) mice cured of EL4 mouse T-cell lymphoma, BCL1 mouse B-cell leukemia and 38C13 mouse B-cell lymphoma by injection of doxorubicin-PHPMA conjugate targeted with monoclonal antibodies (anti-Thy 1.2 for EL4, anti-B1 for BCL1 and anti-CD71 for 38C13) and re-transplanted with a lethal dose of the same cancer cells survive without any treatment considerably longer than control mice; (c) increased NK activity and anti-cancer antibody was detected only in animals treated with doxorubicin-PHPMA conjugate; and (d) considerably increased NK and LAK activity was seen in a human patient treated for generalized breast carcinoma with doxorubicin-PHPMA-IgG.

Doxorubicin bound to a HPMA copolymer carrier through hydrazone bond is effective also in a cancer cell line with a limited content of lysosomes.

We have synthesized conjugates containing doxorubicin (DOX) bound to oligopeptide side chains (GlyGly or GlyPheLeuGly) of a water-soluble copolymer carrier based on poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) either through proteolytically (PK1 conjugates) [Synthetic polymeric drugs. U.S. Patent 5,037,883 (1991)] or hydrolytically cleavable bond (HC conjugates). Pharmacological efficacy of PK1 and HC conjugates was compared in vitro on murine: T-cell lymphoma EL4, B-cell leukemia BCL1, B-cell lymphoma 38C13, leukemia P388 and Con A-stimulated A/Ph splenocytes and on human: primary (SW480) and metastatic (SW620) colorectal cancer cell lines parent and transfected with Thy 1.2 gene [2] and on erythromyeloid leukemia cell line K 562. Inhibition of proliferation determined by 3[H]-thymidine incorporation revealed that the cytostatic effect of HC conjugates is up to two orders of magnitude higher compared to PK1 conjugates. In some cancer cell lines (SW 620/T, SW 480) the pharmacological activity of HC conjugates is in vitro comparable with the activity of the free drug. Unlike PK1 conjugates, HC conjugates with a lysosomally degradable spacer (GlyPheLeuGly) are less effective compared to HC conjugates containing lysosomally non-degradable spacer (GlyGly). Moreover, HC conjugates exert pronounced anti-proliferative activity also in erythroblastoid leukemia cell line K 562 with a limited content of lysosomes.

Antiproliferative effect of a lectin- and anti-Thy-1.2 antibody-targeted HPMA copolymer-bound doxorubicin on primary and metastatic human colorectal carcinoma and on human colorectal carcinoma transfected with the mouse Thy-1.2 gene.

The aim of this study was to compare the potential of two plant lectins [peanut agglutinin (PNA) and wheat germ agglutinin (WGA)], monoclonal antibody (anti-Thy-1.2), its F(ab')(2) fragments, and galactosamine as targeting moieties bound to the polymer drug carrier to deliver a xenobiotic, doxorubicin, to selected cancer cell lines. We have used primary (SW 480, HT 29) and metastatic (SW 620) human colorectal cancer cell lines and a transfectant, genetically engineered SW 620 cell line with mouse gene Thy-1.2 (SW 620/T) to test the possibility of marking human cancer with xenogeneic mouse gene and use it for effective site-specific targeting. The targeting moieties and doxorubicin were conjugated to a water-soluble copolymer based on N-(2-hydroxypropyl)methacrylamide (HPMA) acting as a carrier responsible for controlled intracellular release of the targeted drug. FACS analysis showed a strong binding of WGA-FITC to all tested cell lines. Binding of PNA-FITC was considerably weaker. The in vitro antiproliferative effect of lectin-targeted HPMA carrier-bound doxorubicin evaluated as [(3)H]TdR incorporation reflected both the intensity of the binding and the different sensitivity of the tested cancer cells lines to doxorubicin. The antiproliferative effect of conjugates targeted with WGA was comparable to that with the conjugates targeted with the anti-Thy-1.2 monoclonal antibody or their F(ab')(2) fragments. The magnitude of the cytotoxic effect of HPMA-doxorubicin targeted with PNA was lower in all tested cell lines. While the conjugates with WGA were more cytotoxic, the conjugates with PNA were more specific as their binding is limited to cancer cells and to the sites of inflammation. Noncytotoxic conjugates with a very low concentration of doxorubicin and targeted with PNA, anti-Thy-1.2, or their F(ab')(2) fragments exerted in some lines (SW 480, SW 620) low mitogenic activity. The Thy-1.2 gene-transfected SW 620 metastatic colorectal cancer cell line was sensitive to the antiproliferative effect of Thy-1.2-targeted doxorubicin as was shown for the Thy-1. 2(+) EL4 cell line and for Thy-1.2(+) concanavalin A-stimulated mouse T lymphocytes. These results represent the first indication of the suitability of transfection of human cancer cells with selected targeting genes for site-specific therapy of malignancies.

Health policy for the aged. We don't study the right people.

A review of articles on aging published during one year in seven major U.S. journals in the fields of general medicine, public health and gerontology showed that only a minority of studies took into consideration the factual attributes of the population. Only 53% of the articles included any basic demographic information, usually age. Race was mentioned in 37%, but only 3% studied blacks or Hispanics; socioeconomic status was given in 25%, marital status in 9%, and education in 19%. Regardless of whether demographic factors were detailed in the description of the study, they were rarely used in the analysis. We conclude that information obtained in the course of studies of the elderly may not reflect the actual needs of this population group which must be recognized as heterogeneous. More specific and refined data are needed to set priorities and make policy decisions.

Risk indicators for hospitalization during the last year of life.

OBJECTIVE: High levels of hospital expenditures for older people during their last year of life are widely documented. However, evidence of the association between prospectively measured indicators and subsequent hospitalization is sparse. This article investigates the pattern of hospitalization for a sample of Medicare enrollees during their last year of life. DATA SOURCES: Data from the Longitudinal Study of Aging, a national study of persons age 70 and older, are used. Only data on decedents are used. STUDY DESIGN: We determine individual characteristics (including functional status, evidence of disease, living arrangement, and prior hospitalization) shortly before the last year of life. A distinction is made between terminal and nonterminal admissions. National estimates and regression analyses using survey weights are conducted. PRINCIPAL FINDINGS: The likelihood of any use is high regardless of age, functional status, or the presence of major diseases. Although only a few indicators are associated with having a terminal stay, a number of indicators are associated with nonterminal use. Nonterminal stays and total nights hospitalized are positively associated with prior evidence of disease, prior hospitalization, and age, although the probability of nonterminal use decreases with age for persons over 82 years old. The relationship between use and functional status depends on whether persons lived alone, were institutionalized, or had private health insurance. CONCLUSIONS: This study demonstrates that while it is difficult to predict who will be admitted to the hospital at the time of death, a number of characteristics existing before the last year of life are associated with nonterminal hospitalization and total nights hospitalized during the last year of life.

Disability among older people: United States and Canada.

Data from two national surveys of community-dwelling people 55 years of age and over are the basis of tables presenting 25 measures of disability for each country. The report includes discussions of similarity and differences between the countries, methods used to make the data comparable, and limitations on interpretation of the data.

Trends in medical care and survival from stroke.

Using data from two national surveys in the United States, the National Hospital Discharge Survey and the National Health Interview Survey, we examined whether the incidence of stroke (based on hospitalization rates), the prevalence of stroke, and disability due to stroke had changed. Discharge rates remained virtually constant from 1970 through 1990. At the same time, the proportion of patients who were treated with surgery or other diagnostic procedures increased from 15 to 57% and the proportion who were discharged dead decreased from 20 to 8%. The data suggest that the incidence has not decreased. Hospitalization rates for stroke have changed very little over the past 20 years. Further, neither the prevalence nor the burden of stroke appear to have increased.