[A prospective study on nephrotoxicity induced by continuous infusion of high-dose ifosfamide (15/m2)]

BACKGROUND

A good response rate to high-dose ifosfamide (HDIFO) has been reported in metastatic osteosarcoma and soft tissue tumors. As standard dose of IFO (< 12 g/m2) can give several renal complications and patients previously treated with nephrotoxic drugs are at high risk of nephrotoxicity, a prospective study to evaluate the pattern of nephrotoxicity induced by HDIFO was carried out.

METHODS

Twelve patients (11 metastatic osteosarcoma, 1 synovial sarcoma; mean age 17, R 14-34) were treated with 4 courses of HDIFO/ MESNA (15 g/m2, IV 5 day continuous infusion with bicarbonate and K supplements). All but two were previously treated with cisplatin and methotrexate. Several parameters of renal function were measured before treatment, after each HDIFO course and two months after chemotherapy completion.

RESULTS

Significant changes in the urinary excretion of beta 1-microglobulin, beta 2-microglobulin, Alanine Aminopeptidase, N-Acetil-beta, D-glucosaminidase and a significant reduction in phosphate tubular absorbtion according to the cumulative dose of IFO infused, were observed. Phosphaturia and hypophosphatemia occurred in all the patients studied. In 5 patients, CrCl fell below 70 ml/min with normal serum creatinine level after 45 g/m2 IFO. Plasma bicarbonate concentration less than 20 mmol/l was observed in 5 of 48 HDIFO courses. Glycosuria was detected in 4 patients. Two months after chemotherapy completion, mild glycosuria and slightly reduced CrCl persisted in two patients, whereas the other parameters of renal function studied were similar to the baseline values. An acute, usually reversible subclinical nephrotoxicity involving glomerule and renal tubule was demonstrated in all the patients treated with HDIFO. A persisting subclinical renal impairment was shown with mild glycosuria (2/12 patients) and slightly reduced CrCl (2/12 patients).

Cytokine production and adhesive protein expression by endothelial cells after contact with polyethylene terephthalate

The authors have evaluated adhesive protein expression and cytokine production by human umbilical vein endothelial cells cultured in contact with polyethylene terephthalate (PET). ELAM-1, ICAM-1 and VCAM-1 expression was determined by flow cytometry; the concentration of interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6), granulocyte colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) in the supernatant was determined by enzyme immunoassay. The contact with PET determined a significant increase in ELAM-1 expression and insignificant increase in cytokine production, demonstrating that PET had a limited capability to stimulate endothelial cells in a pro-inflammatory sense.

Effects of orally administered bisphosphonates on bone loss in a disuse osteopenia model involving the rat

OBJECTIVE

This study was carried out to evaluate the effectiveness of two newly synthesized bisphosphonates (BPs) [Alendronate (4-amino-1-hydroxybutylidene-1, 1-bisphosphonic acid (AHBuBP)) and Neridronate (6-amino-1-hydroxyhexylidene-1,1-bisphosphonic acid (AHHexBP)], administered orally, in reducing experimentally induced bone loss.

METHODS

Unilateral sciatic nerve section was performed on the Sprague-Dawley rat to induce osteopenia in one of the hind limbs. Histomorphometric measurements of the tibial trabecular bone and femur ash content determinations were effected to assess the degree of osteopenia. For comparison Chlodronate (dichloromethylene-1-bisphosphonic acid (Cl2MBP) was employed as the reference drug.

CONCLUSIONS

The results of this investigation show that both BPs were significantly active in reducing the osteopenic process in the involved limb and were more active than Chlodronate.

In vitro assessment of phagocytosis of bovine collagen by human monocytes/macrophages using a spectrophotometric method

The use of a wound dressing with covering and haemostatic properties significantly improves wound healing. In this study, a lyophilized bovine collagen sponge used for the treatment of wounds and ulcerae has been tested in a cell culture system. Phagocytosis of collagen fragments by human blood monocytes/macrophages has been investigated. For the assessment of collagen ingestion by mononuclear phagocytes, a picrosirius dye specific for collagen molecules has been used. By adapting this histochemical technique to microplate cell culture system, replicate monocyte cultures are assayed. Collagen content is determined by evaluating spectrophotometrically at 540 nm the absorbance of a sirius red/picric acid solution. Using this simple and sensitive method, the phagocytosis of bovine collagen by LPS-stimulated monocytes/macrophages has been ascertained.

Bone turnover in patients on home parenteral nutrition: alongitudinal observation by biochemical markers

In order to characterize biochemical markers of bone turnover in home parenteral nutrition(HPN) patients, 8 adult patients on HPN for benign intestinal failure were studied at 0, 6 and 12 months by evaluating serum osteocalcin (bone formation marker), urinary hydroxylysyl pyridinoline, lysyl pyridinoline and beta-galactosyl hydroxylysine (bone resorption markers), serum PTH, Calcitonin, 25 vitD, 1-25vitD, serum and urinary minerals, body weight, rehabilitation degree and HPN characteristics. Three patients entered the study 2-3 months after the beginning of HPN. Their features of bone turnover were homogeneous, characterized by increased resorption associated with normal or increased formation, at baseline, and normalization of resorption associated with an increase or a parallel decrease of formation, at 6 months. At 12 months, the patterns were similar to those observed at 6 months. The patients were not of the same sex and age and had different underlying diseases and types of intestinal failure, HPN composition and serum vitamin D levels. They had weight gain that was already present at baseline and the positive outcomes of the rehabilitation and clinical status in common. Five patients entered the study more than 1 year after the beginning of HPN. They showed heterogeneous features of bone turnover that were stable throughout the study, characterized by increased resorption associated with low or normal formation in two cases, low normal resorption associated with low or normal formation in three. In one patient, who had increased resorption and low formation, the bone turnover appeared to be explained by the nutritional and clinical outcomes, which were negative. These results appeared consistent with those obtained in previous studies by bone histomorphometry, indicating that bone turnover of short-term HPN patients differed from that of long-term patients, and suggesting that the early months of HPN were associated with increased bone resorption.

Application of a combination of neutral red and amido black staining for rapid, reliable cytotoxicity testing of biomaterials

Cell viability and growth for cytotoxicity evaluation of materials for prosthetic devices has been tested using various methods. The aim of this study was to extend the choice of reliable methods to quantify cytotoxicity of materials in vitro. By measuring both viability and growth of cells exposed to biomaterials in vitro, two different parameters are analysed and quantified upon reading of the absorbance of coloured solutions in a spectrophotometer. Neutral red uptake and amido black staining of cells have been used for cell viability and cell number measurement, respectively: they have been found to be well correlated with the number of surviving cells. These methods have been adjusted to a 96-well microplate cell culture system and re-evaluated as simple and reliable methods for the quantitative assessment of biomaterial effect on cells.

Assessment of metal extract toxicity on human lymphocytes cultured in vitro

In this study the toxic effects of chromium, nickel, and cobalt extracts on in vitro cultured lymphocytes were evaluated. Graphite furnace atomic absorption spectrometry was used to measure the ion concentration. After serial dilution of the extracts, the viability of lymphocytes at 24, 48, and 72 h was estimated by flow cytometry, including propidium iodide staining and light scatter property assessment, and by MTT reduction test. The results of the investigation allowed us to conclude that 1) standardization of the procedure for preparing extracts is fundamental to obtaining repeatability of results; 2) the toxicity of an extract cannot be evaluated with a single viability assay; a combination of functional and structural tests is required; 3) when methods based on enzymatic reactions are performed, e.g. MTT test, it is advisable to replace the extract containing metal ions with fresh medium in order to avoid any interference with viability testing; 4) the amount of Co and Ni in the extract is similar, but the Cr release is very poor; 5) the lower toxicity of Cr extract probably is due to the lower ion concentration; 6) the assessment of 50% cytotoxic concentration (TC50) allows quantification of materials toxicity and comparison of various metals; and 7) the determination of a noncytotoxic concentration, i.e., a concentration lower than TC10, is required for subsequent investigation of cell functions because such studies can be carried out only on viable cell population.

Activation of the plasma coagulation system induced by some biomaterials

The ability of some biomaterials to activate plasma coagulation system was examined in vitro. After contact of platelet-rich plasma with biomaterials, some markers of the thrombin formation, i.e., fragment 1 + 2 and fibrinopeptide A, and some inhibitors of the blood coagulation mechanism were tested. Fragment 1 + 2 and fibrinopeptide A were found to be increased by all of the materials, though to a different extent. In particular, fragment 1 + 2 and fibrinopeptide A were significantly increased upon contact with polybutylene terephthalate and with collagen coated polyethylene terephthalate, respectively. Also antithrombin III was shown to decrease following exposure to biomaterials, but statistical significance was found only for polyethylene terephthalate and polyvinylacetate. As a results of this wide range of variability in the parameters, it is advisable to explore the plasma coagulation system with a multiparametric approach in which thrombin formation and coagulation inhibitors are thoroughly investigated.

The relationship of dehydroepiandrosterone sulfate (DHEAS) to endocrine-metabolic parameters and functional status in the oldest-old. Results from an Italian study on healthy free-living over-ninety-year-olds

Dehydroepiandrosterone sulfate (DHEAS), the major circulating adrenal hormone, has been suggested to have a role in many aging related diseases and perhaps in aging itself. Its precise biologic effects are still unknown, and data on healthy people over 90 yr of age are not available. We measured serum DHEAS levels in 75 healthy subjects aged 90-106 yr of both sexes and searched for correlations between DHEAS and several endocrine-metabolic parameters (serum thyroid hormones, GH-insulin-like-growth factor I (GH-IGF-I) axis, serum lipid profile, anthropometric indices of body composition) of the same subjects. The resulting data, normalized by logarithmic transformation (geometric mean at age 90-99, 551 ng/mL in men, 364 ng/mL in women; at age > 100 yr, 404 ng/mL in men, 521 ng/mL in women) resulted five-fold lower than DHEAS levels measured in a young control group (geometric mean at < 40 yr of age, 3110 ng/mL in men, 2824 ng/mL in women). In women over ninety yr, DHEAS was positively correlated with serum free triodothyronine (FT3) levels (r = 0.34, P = 0.05) and inversely with triglycerides (r = -0.45, P = 0.05). In men over 90 yr, DHEAS had positive correlations with body mass index (r = 0.41, P < 0.03) and waist-to-hip ratio (r = 0.47, P < 0.01) taken as indices of body's energy reserves (fat). To determine whether low serum DHEAS levels predict poor functional status in the very old, the Activity Daily Living (ADL) test was administered in all over-ninety subjects. Men with the highest functioning levels had the highest DHEAS levels (P < 0.03). Our data suggest that DHEAS levels may influence and/or be influenced by several endocrine and metabolic features of oldest-old people, depending on the sexual steroid milieu. DHEAS seems also to have a strong interrelation with functional activities. A favorable role for DHEAS in successful aging is proposed.

[In vitro tissue factor production by human endothelial cells put in contact with polyethylene terephthalate with different texture]

The aim of this study is the evaluation of the in vitro tissue factor production by endothelial cells cultured in the presence of Woven or Knitted Dacron. The spectrophotometric evaluation of the protein content of the cultures and the both indirect assay and enzyme immune assay of tissue factor in cellular lysates were carried out after 72 hour contact between the cells and the materials under examination. The endothelial cell contact with Knitted Dacron did not determine variation in protein content, but it induced a significant increase in tissue factor production. The endothelial cell contact with Woven Dacron determined no significant variations neither in the protein content nor in the tissue factor concentration. It is concluded that Knitted Dacron, through the induction of tissue factor synthesis, can favour the extrinsic pathway of coagulation and therefore the production of thrombi. Woven Dacron, not inducing tissue factor formation, does not activate the extrinsic pathway of coagulation, as for the mechanism considered.

[Assessment of various immunologic parameters in silicone implant carriers]

The Authors evaluated some immunological parameters in women carrying silicone gel-filled breast implants for over one year. Peripheral blood samples from 22 patients were examined in order to assess both the antigenic pattern of lymphocyte subpopulations by cytofluorimetric analysis, and the cell proliferation of PHA-stimulated lymphocytes by the uptake of tritiated thymidine. These tests were performed at the time of the sample withdrawal and after in vitro reexposure to silicone extract for 48-72h. Changes in lymphocyte subpopulations and functional response were observed when patients were divided into groups according to the type of surgery, i.e. breast augmentation or reconstruction, or to the degree of periprosthetic capsular contracture. These results suggest the possibility of an interaction between silicone and the immune system, which cannot be disregarded for the explanation of the silicone related complications.

Adhesive protein expression on endothelial cells after contact in vitro with polyethylene terephthalate coated with pyrolytic carbon

This research aims at evaluating the expression of some adhesive proteins on endothelial cell surface with polyethylene terephthalate coated with pyrolytic carbon (PET + PC). Twenty-two different cultures of human umbilical vein endothelial cells (HUVECs) were put in contact with PET + PC. Both HUVECs grown without the biomaterial and HUVECs incubated with endotoxin were used as control. After 24 h, platelet endothelial cell adhesion molecule-1 (PECAM-1), endothelial leukocyte adhesion molecule-1 (ELAM-1), intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were evaluated on the cells by monoclonal antibodies and flow cytometry. In agreement with the literature, after 24 h the culture incubated with endotoxin determined a significant increase in the percentage of positive cells for ELAM-1, a significant increase in fluorescence intensity of ICAM-1, and a significant increase in the percentage of positive cells and fluorescence intensity for VCAM-1. After 24 h of culture with PET + PC, no significant variations in the antigens examined were observed. This demonstrates that such material does not activate in vitro the proteins involved in the adhesion between leucocytes and endothelium or in the adhesion between endothelial cells themselves.

[European regulations concerning medical devices]

The employment in clinical practice and prosthetic surgery of a number of medical devices implies a great responsibility to the operators so as to make the knowledge of existing regulations mandatory. The authors illustrate the problems concerning the free circulation of medical devices within the European market. They describe the new strategy of EEC which led to the definition of the directives which apply to all medical devices and of the harmonized standards for inspecting their biological effects. The appointment of certification bodies and the accreditation of Testing Laboratories are described. Finally, particular attention is given to product certification, which is compulsory for the pre-market approval of medical devices.

Evaluation of several immunological parameters in patients with aseptic loosening of hip arthroplasty

The authors evaluated several immunological parameters in patients with loosened hip arthroplasty in order to determine the state of sensitization with regard to the metallic constituents of the prosthesis. The results obtained by in vivo epicutaneous testing did not reveal a correlation between loosening and sensitization, as the patch test was positive in only 1 out of 16 cases examined. An evaluation of the lymphocyte subpopulation on peripheral blood demonstrated that patients with prostheses in Cr, Co, Mo, Ni alloy present significant lymphopenia, with a reduction in subpopulations CD4 and CD8 and a decrease in in vitro cytotoxic activity. The meaning of these modifications could be interpreted to be either a toxic effect products released from the implant, or as the recruitment of lymphocytes in the site of loosening, due to lymphocyte sequestration phenomena consequent to a cell-mediated hypersensitivity reaction.

[Evaluation of the biocompatibility of medical devices based on European standards]

Several issues concerning the biocompatibility) testing of medical devices as stated in European directive 90/385 and 93/42 are discussed. The authors describe the fundamental characteristics that biomaterials should have to be employed in the human body, the assays useful for testing different aspects of biocompatibility and the harmonized regulations already available or under development. The testing protocol applied by the a. in their Lab covering many issues of biocompatibility is presented: a body of experience was gained over the years and it has been revised under the new regulatory items. In conclusion, the biocompatibility of devices must be assessed following the European harmonized standards, the available. Where proper standards are still lacking, feasible testing methods, even if not officially adopted yet, have to be used.

In vitro effects of bone cements on the cell cycle of osteoblast-like cells

The effects of orthopaedic cements on the proliferation and cell cycle of in vitro cultured MG63 osteoblast-like cells were examined. Five different cements were mixed and extracted at different time intervals (15 and 60 min, 6, 24 and 48 h). Cell proliferation inhibition (CPI) was evaluated after 72 h culture as the toxicity parameter. As for the toxicity degree, the extracts were considered to have 'high toxicity' (CPI > or = 50%), 'medium toxicity' (50% > CPI > 25%), 'low toxicity' (CPI < or = 25%) and 'no toxicity' (CPI = 0). Cell cycle phases of MG63 cells were evaluated at 24, 48 and 72 h by flow cytometry; the DNA content was assessed using the propidium iodide uptake and the percentage of cells in the S phase was determined using 5'-bromodeoxyuridine uptake. According to our results, the toxicity is inversely correlated with the time interval between polymerization and extract preparation, and is different according to the cement type. For some cements the effects are still observed 48 h after polymerization. The damaging effect is not linked to a specific phase of the cell cycle, nor does it hamper the restarting of cell proliferation at 72 h.

The effects of orthopaedic cements on osteoblastic cells cultured in vitro

The authors have examined the response of osteoblastic cells in contact in vitro with different acrylic cements used in orthopaedic surgery. The solid and liquid components of the cements were mixed in sterile environments according to the instructions provided by the manufacturers, and placed in contact with the cells 1/2, 1, 4, 6 and 24 hours after triggering of polymerization. The experimental model, that tends to define the kinetics of the release of toxic substances from acrylic cements, allowed to verify 24 hours after polymerization that the three cements had lost their toxic effects, which instead had been present to varying degrees for the first 1-6 hours. Cytomorphological observations did not reveal cellular damage, which instead was very clear when functional tests were used.

Platelet and coagulation factor variations induced in vitro by polyethylene terephthalate (Dacron) coated with pyrolytic carbon

The haemocompatibility of polyethylene terephthalate (Dacron) coated with pyrolytic carbon was examined in vitro, evaluating its capability of inducing adhesion and platelet activation, and of modifying the intrinsic coagulation pathway. Platelet adhesion was evaluated by counting platelets before and after in vitro contact of human plasma with the material under examination. Platelet activation was evaluated by determining platelet factor 4 (PF4) and thromboxane B2. Intrinsic coagulation pathway alterations were studied by determining activated partial thromboplastin time (APTT) and the activity of single factors. The results obtained show that pyrolytic carbon-coated Dacron induces platelet adhesion, reduction in platelet volume and lower increase in thromboxane production than that obtained after contact with uncoated Dacron. Pyrolytic carbon-coated Dacron does not induce PF4 release, contrary to uncoated Dacron induces a significant release. Moreover, pyrolytic carbon-coated Dacron, induces a significant extension of APTT by reducing the activity of intrinsic pathway factors, particularly factor XI.

Microhardness of bone at the interface with ceramic-coated metal implants

We evaluated bone microhardness at the interface with hydroxyapatite-coated stainless-steel pins used in an external fracture fixation system. Pins were transversally inserted into the diaphyses of sheep tibiae and were loaded in for 6 weeks. Uncoated pins were implanted as controls. Microhardness analysis, based on the measure of the resistance of the bone to the penetration of a small diamond pyramid, yielded an accurate and reproducible measure of the mineralization degree and of the orientation of collagen fibers. Bone tissue close to the pin is less hard than bone tissue far from it. Moreover, the presence of hydroxyapatite coating on the pins did not significantly affect bone hardness; actually, the mean hardness at the interface with the pins was 56.9 Vickers degrees, whereas at the interface with the uncoated pins it was 62.2. It can be concluded that, 6 weeks postsurgery, the bone growing into the threadings of a loaded screwed implant reached maturity at a degree lower than that of the host bone in both uncoated and coated implants.

Seven surgical silicones retain Staphylococcus aureus differently in vitro

In an in vitro study, we have quantitatively evaluated the capability of seven different types of silicone to retain a Staphylococcus aureus strain, isolated from a surgical wound. All the silicone specimens were taken from prostheses already used in plastic or ophthalmological surgery. Two polymers were used as controls: polystyrene, because of its known capability to favour in vitro bacterial recovery, and nylon, for its bacterial repellence. The results show that all silicones are suitable substrata for Staphylococcus aureus. However, there are some differences among silicone types. The amounts of bacteria retained from silicone oils are greater than or equal to those obtained from the positive control material.

Disposable contact lenses and bacterial adhesion. In vitro comparison between ionic/high-water-content and non-ionic/low-water-content lenses

An in vitro quantitative study of the adhesion of a Staphylococcus aureus strain to two types of disposable contact lenses has been carried out. The first type was an ionic/high-water-content (I-HWC) lens (42% Etafilcon A, 58% water) and the second was a non-ionic/low-water-content (Nl-LWC) lens (61.4% poly(2-hydroxyethyl methacrylate), 38.6% water). Adhesion to the two lens types was evaluated both in basic conditions and after treatment with lysozyme. The results showed that I-HWC lenses are more prone to Staphylococcus aureus adhesion than NI-LWC lenses, both untreated (+15.4%) and treated with lysozyme (+20.5%). Lysozyme increased bacterial adhesion by 30.5% on the lenses with lower water content, and by 36.3% on those with higher water content.

Microstructural investigation of bone-cement interface

We evaluated the microstructural characteristics of newly formed bone tissue at the interface with cement. The bone-cement interfaces of the femoral components of nine hip prostheses retrieved after loosening were investigated by means of X-ray diffraction on microareas and microhardness. The bone far from the interface of two stable prostheses was used as a control. The newly formed bone adjacent to cement in the loosened prostheses showed a maturity degree lower than that of bone adjacent to cement in stable prostheses. The lattice parameters of bone apatite did not show significant variations as compared to the reference values. Bone trabeculae at the interface with loosened prostheses often showed an osteoid lining characterized by a strongly demineralized lamellar and haversian structure. Radioopaque cement particles are sometimes found in the trabecular bone tissue around the prosthesis.

Hormonal changes in male subjects over-ninety

The physiology of aging in very old people is still poorly understood. A wide variety of age-related factors confuse the interpretation of existing data, especially as regards the modifications of the endocrine system. The effect of age on the gonad-hypophyseal function was studied in 26 over ninety-year-old males and compared with a control aged between 27 and 88, subdivided into age groups. The serum levels of total testosterone were stable up to the ninth decade while they were lower in the over ninety-year-olds; free testosterone and its peripheral metabolites (estrogens and dehydrotestosterone) were also lower in the over ninety-year-olds with respect to the others, although the decrease had started more gradually at about the fourth decade. Sex-hormone-binding-globulin, the main serum carrier of testosterone, increased gradually with age. The levels of hypophyseal gonadotropins were constant up to the ninth decade where a significant and abrupt increase was observed. The data suggest the presence of marked alterations of the testicular-hypophyseal axis in the later decades of life, with important repercussions on the pattern of circulating sex steroids.

Assessment of viability and proliferation of in vivo silicone-primed lymphocytes after in vitro re-exposure to silicone

The functional response of peripheral blood lymphocytes isolated from 22 patients with silicone gel-filled breast implants was assessed after in vitro re-exposure to silicone. Using cell culture test methods to quantify proliferation and viability and/or activation of lymphocyte microcultures, i.e., the uptake of tritiated thymidine (3H-TdR uptake test) and the reduction of formazan salts (MTT assay), interesting data were obtained. Peripheral blood lymphocytes purified from patients wearing silicone gel-filled breast implants react in vitro to silicone showing a statistically significant increase of both proliferation and viability, while healthy subjects do not respond on in vitro exposure to silicone. Differences resulted even more statistically significant when patients were divided into two groups depending on the type of surgery they underwent: patients with breast augmentation for aesthetic reasons seem to have an increased responsiveness in vitro to silicone compared to patients who experienced a reconstructive surgery of the breast. Although they are still preliminary, being referred to a limited population, these results suggest that the lymphocytes of patients with silicone gel-filled breast implants could be sensitized in vivo toward silicone; the re-exposure of these cells to silicone leads to a higher functional response which could be looked for by using quantitative in vitro test methods.

In vitro biocompatibility of a polyurethane catheter after deposition of fluorinated film

The in vitro biocompatibility of an experimental surface-treated polyurethane was compared with an untreated polyurethane already used for intravascular catheters. The experimental surface was coated with a fluorinated film using a glow discharge treatment. Neither of the catheters was cytotoxic for L929 murine fibroblasts, caused platelet adhesion or release reaction, or changed the mean platelet volume. The surface-treated polyurethane, however, caused a higher adhesion of Staphylococcus aureus than did the untreated one. Therefore, using in vitro testing, it has been ascertained that the examined material, though not being cytotoxic and not modifying platelet behaviour, could favour bacterial adherence.