Targeting of doxorubicin to the urinary bladder of the rat shows increased cytotoxicity in the bladder urine combined with an absence of renal toxicity

Targeting of anti-tumor drugs to the urinary bladder for the treatment of bladder carcinoma may be useful, since these agents generally have a low degree of urinary excretion and are highly toxic elsewhere in the body. The anti-tumor drug doxorubicin was coupled to the low-molecular weight protein lysozyme via the acid-sensitive cis-aconityl linker. All free amino groups of the lysozyme were used for drug attachment to achieve intact excretion of the doxorubicin-aconityl-lysozyme conjugate into the bladder. In the bladder, the cytotoxic drug should be regenerated through acidification of the urine. First, the doxorubicin-aconityl-lysozyme conjugate was tested in rats for its target specificity and general toxicity. Wistar rats were injected intravenously with 2 mg/kg free doxorubicin or 10 mg/kg lysozyme-conjugated doxorubicin. Total urinary excretion of doxorubicin was about 10 times higher if the drug was coupled to lysozyme (39 +/- 3% versus 4.4 +/- 0.4%). Free doxorubicin had no detectable toxic effects on heart, liver and lung but caused severe renal damage (proteinuria, N-acetylglucosaminidase excretion and glomerulosclerosis). None of the rats injected with doxorubicin-lysozyme conjugate showed such renal toxicity. Second, we tested whether doxorubicin could be released from the conjugate in the bladder through acidification of the urine and if the released doxorubicin could still exert a cytotoxic effect. Doxorubicin-aconityl-lysozyme (2 mg/kg conjugated doxorubicin, i.v.) was administered in rats with acidified urine (pH 6.1 +/- 0.1) and in rats with a high urinary pH (8.2 +/- 0.4). Ten times more doxorubicin was released from the conjugate in the group with acidified urine (15 +/- 7% versus 1.7 +/- 0.1%). In agreement with this, cytotoxicity was also higher in the low pH group (IC50 of 255 +/- 47 nM versus 684 +/- 84 nM doxorubicin). In conclusion, a specific delivery of doxorubicin to the urinary bladder combined with a reduced toxicity of doxorubicin in the kidneys can be achieved by coupling this anti-tumor drug to the low-molecular weight protein lysozyme via an acid-labile linker. A release of cytotoxic doxorubicin in the urinary bladder can be achieved by acidification of the urine. This technology, after further optimization, may provide an interesting tool for the treatment of bladder carcinoma.     

Mitotane increases the blood levels of hormone-binding proteins

In 3 patients with adrenocortical carcinoma the effects of long-term mitotane therapy on the serum levels of three hormone-binding globulins and vitamin D-binding protein were studied. Within the first month of treatment cortisol-binding globulin increased two to three times, in close correlation with sex hormone-binding globulin. The rises in thyroxine-binding globulin and vitamin D-binding protein were considerably less. Elevated cortisol-binding protein appeared to be associated with increased binding of cortisol, whereas the binding of thyroxine and vitamin D remained below normal. Binding proteins returned to normal in 2 patients within a year after mitotane discontinuation. This phenomenon of hormone-binding protein enhancement invalidates the use of total serum hormone levels to monitor the effects of mitotane on endocrine function and could provide an explanation for the increased cortisol substitution requirement during mitotane therapy.     

1H-NMR spectroscopy of cerebrospinal fluid of fetal sheep during hypoxia-induced acidemia and recovery

The purpose of the study was to investigate the sequence of processes occurring during and after hypoxia-induced acidemia. We used proton nuclear magnetic resonance spectroscopy, which provides an overview of metabolites in cerebrospinal fluid (CSF), reflecting neuronal metabolism and damage. The pathophysiological condition of acute fetal asphyxia was mimicked by reducing maternal uterine blood flow in 14 unanesthetized pregnant ewes. CSF metabolites were measured during hypoxia-induced acidemia, and during the following recovery period, including the periods at 24 and 48 h after the hypoxic insult. Maximum values of the following CSF metabolites were reached during severe hypoxia (pH 相似文献   

Hypoxia in fetal lambs: a study with (1)H-MNR spectroscopy of cerebrospinal fluid

In fetal lambs, severe hypoxia (SH) will lead to brain damage. Mild hypoxia (MH) is thought to be relatively safe for the fetal brain because compensating mechanisms are activated. We questioned whether MH, leading to mild acidosis, induces changes in cerebral metabolism. Metabolites in cerebrospinal fluid (CSF) samples, as analyzed by proton magnetic resonance spectroscopy, were studied in two groups of seven anesthetized near-term fetal lambs. In group I, SH leading to acidosis with an arterial pH <7.1 was achieved. In group II, MH with an intended pH of 7.23--7.27 was reached [start of MH (SMH)], and maintained during 2 h [end of MH (EMH)]. During SH, choline levels in CSF, a possible indicator of cell membrane damage, were increased. Both during SH and at EMH, CSF levels of lactic acid, alanine, phenylalanine, tyrosine, lysine, branched chain amino acids, and hypoxanthine were increased compared with control values and with SMH, respectively. At EMH, the hypoxanthine CSF-to-blood ratio was increased as compared with SMH. These results indicate that prolonged MH leads to energy degradation in the fetal lamb brain and may not be as safe as assumed.     

Paget's disease of bone: early and late responses to three different modes of treatment with aminohydroxypropylidene bisphosphonate (APD)

Early and late responses to treatment with either oral (600 mg/day) or intravenous (20 mg/day) (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (aminohydroxypropylidene bisphosphonate; APD) were studied in 142 patients with Paget's disease of bone who had not previously been treated with bisphosphonate. The efficacy of three therapeutic regimens was compared: (a) oral aminohydroxypropylidene bisphosphonate given continuously until six months after the serum alkaline phosphatase activity had returned to normal (long term); (b) oral aminohydroxypropylidene bisphosphonate given until urinary hydroxyproline excretion had returned to normal (short term); (c) intravenous aminohydroxypropylidene bisphosphonate for 10 days. With either oral or intravenous treatment the decrease in urinary hydroxyproline excretion was rapid and always preceded the fall in serum alkaline phosphatase activity. Normal urinary hydroxyproline excretion is essential for return of the serum alkaline phosphatase activity to normal. Complete biochemical remission, defined as return of the serum alkaline phosphatase activity to normal, was obtained in 129 patients (91%). The median duration of remission as assessed by actuarial analysis was 2.7 years. This study found no difference in the long term among the three modes of treatment, suggesting that for most patients with Paget's disease a short course of intravenous aminohydroxypropylidene bisphosphonate will produce longlasting, complete remission without need for maintenance treatment.