Effects of antihypertensive drugs on blood pressure and proteinuria in childhood

BACKGROUND: Historically, there have been few drug trials for antihypertensive treatment in childhood and recommendations have been extrapolated from data obtained in adulthood. During the last decade an increased awareness of the risks of childhood hypertension stimulated clinical trials of antihypertensive agents in children. OBJECTIVE: The aim of this article is to systematically review the studies published between 1995 and 2006 that deal with the effect of antihypertensive drugs on childhood hypertension or proteinuria. METHODS: Medline, Current Contents, personal files and reference lists were used as data sources. RESULTS: Fifty-two out of 79 initially found reports were excluded. Consequently 27 articles were retained for the final analysis. The blood pressure reduction was similar with angiotensin-converting enzyme inhibitors (10.7/8.1 mmHg), angiotensin II receptor antagonists (10.5/6.9 mmHg) and calcium-channel blockers (9.3/7.2 mmHg). In addition angiotensin-converting enzyme inhibitors (by 49%) and angiotensin II receptor antagonists (by 59%) significantly reduced pathological proteinuria. CONCLUSIONS: The blood pressure reduction of angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists and calcium-channel blockers is almost identical. In children with pathological proteinuria angiotensin-converting enzyme inhibitors or angiotensin II antagonists are superior to calcium-channel blockers.

Prescription of drugs blocking the renin-angiotensin system in Italian children

Little is known about the prescription pattern of antihypertensive drugs for children with impaired kidney function. We have therefore documented the use of antihypertensive drugs in this patient group by evaluating the Italian pediatric population-based registry of patients with chronic kidney disease on conservative treatment (ItalKid) from 1995 to 2003. In 1995, prescriptions written for antihypertensive drugs for use by children were approximately equally divided among drugs blocking the renin-angiotensin system and calcium channel blockers (38 vs. 43% of all prescriptions), followed by beta-blockers and diuretics (15 and 4%, respectively). During subsequent years the proportion of prescriptions for drugs blocking the renin-angiotensin system increased (2003: 61%; p<0.001) and that of calcium channel blockers decreased (2003: 18%, p<0.001). In 1995, blockers of the renin-angiotensin system were prescribed, either as monotherapy or in combination, in 53% of the patients, but the relative frequency of the patients prescribed these drugs increased up to 83% in 2003 (p<0.0005). In conclusion, physicians caring for Italian children with impaired kidney function are increasingly prescribing drugs blocking the renin-angiotensin system.

[Will type I diabetes mellitus be treated with immunosuppressive drugs in the future?]

Even if the pathogenesis of type-I (insulin-dependent) diabetes mellitus is still not clarified in every detail, there is general agreement that this form of diabetes is induced by autoimmune mechanisms leading to beta-cell destruction. Therefore, it should theoretically be feasible to suppress the mechanism leading to type-I diabetes with appropriate and early immunotherapy. The current clinical data clearly document that the rate and duration of remissions in patients with newly diagnosed type-I diabetes can be increased significantly using appropriate immunosuppressive regimens. However, before these therapies can become standard therapy of type-I diabetes, the following important clinical requirements have to be fulfilled: the toxicity (especially to kidneys and beta-cells) has to be reduced, the patients should be diagnosed and treated in 'pre-diabetic' states, more selective immunosuppressive regimens have to be available in order to reduce the occurrence of treatment-associated lymphomas and neoplasias. Since accurate detection of 'pre-diabetic' patients is difficult and presents an immense logistic problem, it may take a long time before large-scale immunosuppressive therapies of type-I diabetes are feasible.

Loss of the high-affinity pentamidine transporter is responsible for high levels of cross-resistance between arsenical and diamidine drugs in African trypanosomes

Treatment of many infectious diseases is under threat from drug resistance. Understanding the mechanisms of resistance is as high a priority as the development of new drugs. We have investigated the basis for cross-resistance between the diamidine and melaminophenyl arsenical classes of drugs in African trypanosomes. We induced high levels of pentamidine resistance in a line without the tbat1 gene that encodes the P2 transporter previously implicated in drug uptake. We isolated independent clones that displayed very considerable cross-resistance with melarsen oxide but not phenylarsine oxide and reduced uptake of [(3)H]pentamidine. In particular, the high-affinity pentamidine transport (HAPT1) activity was absent in the pentamidine-adapted lines, whereas the low affinity pentamidine transport (LAPT1) activity was unchanged. The parental tbat1(-/-) line was sensitive to lysis by melarsen oxide, and this process was inhibited by low concentrations of pentamidine, indicating the involvement of HAPT1. This pentamidine-inhibitable lysis was absent in the adapted line KO-B48. Likewise, uptake of the fluorescent diamidine 4',6-diamidino-2-phenylindole dihydrochloride was much delayed in live KO-B48 cells and insensitive to competition with up to 10 muM pentamidine. No overexpression of the Trypanosoma brucei brucei ATP-binding cassette transporter TbMRPA could be detected in KO-B48. We also show that a laboratory line of Trypanosoma brucei gambiense, adapted to high levels of resistance for the melaminophenyl arsenical drug melarsamine hydrochloride (Cymelarsan), had similarly lost TbAT1 and HAPT1 activity while retaining LAPT1 activity. It seems therefore that selection for resistance to either pentamidine or arsenical drugs can result in a similar phenotype of reduced drug accumulation, explaining the occurrence of cross-resistance.

Rifampin for therapy of experimental pneumococcal meningitis in rabbits

Rifampin at a maximally effective dose was less active than ceftriaxone (both drugs at 10 mg/kg of body weight.h) in a rabbit model of pneumococcal meningitis (delta log10 CFU/ml.h, -0.40 +/- 0.13 versus -0.77 +/- 0.18; P < 0.01). The bactericidal activity of rifampin decreased at concentrations in cerebrospinal fluid greater than those that are clinically achievable, and use of rifampin in combination with ofloxacin had no synergistic or additive effect.

Inhibition of ErbB2/neuregulin signaling augments paclitaxel-induced cardiotoxicity in adult ventricular myocytes

Paclitaxel (Taxol) has been successfully combined with the monoclonal antibody trastuzumab (Herceptin) in the treatment of ErbB2 overexpressing cancers. However, this combination therapy showed an unexpected synergistic increase in cardiac dysfunction. We have studied the mechanisms of paclitaxel/anti-ErbB2 cardiotoxicity in adult rat ventricular myocytes (ARVM). Myofibrillar organization was assessed by immunofluorescence microscopy and cell viability was tested by the TUNEL-, LDH- and MTT-assay. Oxidative stress was measured by DCF-fluorescence and myocyte contractile function by video edge-detection and fura-2 fluorescence. Treatment of ARVM with paclitaxel or antibodies to ErbB2 caused a significant increase in myofilament degradation, similarly as observed with an inhibitor of MAPK-signaling, but not apoptosis, necrosis or changes in mitochondrial activity. Paclitaxel-treatment and anti-ErbB2 reduced Erk1/2 phosphorylation. Paclitaxel increased diastolic calcium, shortened relaxation time and reduced fractional shortening in combination with anti-ErbB2. A minor increase in oxidative stress by paclitaxel or anti-ErbB2 was found. We conclude, that concomitant inhibition of ErbB2 receptors and paclitaxel treatment has an additive worsening effect on adult cardiomyocytes, mainly discernible in changes of myofibrillar structure and function, but in the absence of cell death. A potential mechanism is the modulation of the MAPK/Erk1/2 signaling by both drugs.

Covalent modification of GABAA receptor isoforms by a diazepam analogue provides evidence for a novel benzodiazepine binding site that prevents modulation by these drugs

Classical benzodiazepines, for example diazepam, interact with alpha(x)beta(2)gamma(2) GABA(A) receptors, x = 1, 2, 3, 5. Little is known about effects of alpha subunits on the structure of the binding pocket. We studied here the interaction of the covalently reacting diazepam analog 7-Isothiocyanato-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one (NCS compound) with alpha(1)H101Cbeta(2)gamma(2) and with receptors containing the homologous mutation, alpha(2)H101Cbeta(2)gamma(2), alpha(3)H126Cbeta(2)gamma(2) and alpha(5)H105Cbeta(2)gamma(2). This comparison was extended to alpha(6)R100Cbeta(2)gamma(2) receptors as this mutation conveys to these receptors high affinity towards classical benzodiazepines. The interaction was studied at the ligand binding level and at the functional level using electrophysiological techniques. Results indicate that the geometry of alpha(6)R100Cbeta(2)gamma(2) enables best interaction with NCS compound, followed by alpha(3)H126Cbeta(2)gamma(2), alpha(1)H101Cbeta(2)gamma(2) and alpha(2)H101Cbeta(2)gamma(2), while alpha(5)H105Cbeta(2)gamma(2) receptors show little interaction. Our results allow conclusions about the relative apposition of alpha(1)H101 and homologous positions in alpha(2), alpha(3), alpha(5) and alpha(6) with the position occupied by -Cl in diazepam. During this study we found evidence for the presence of a novel site for benzodiazepines that prevents modulation of GABA(A) receptors via the classical benzodiazepine site. The novel site potentially contributes to the high degree of safety to some of these drugs. Our results indicate that this site may be located at the alpha/beta subunit interface pseudo-symmetrically to the site for classical benzodiazepines located at the alpha/gamma interface.

Update on safety during pregnancy of biological agents and some immunosuppressive anti-rheumatic drugs

A consensus paper concerning the interaction of anti-rheumatic drugs and reproduction was published in 2006, representing data collected during the year 2004 and 2005. Because of an increasing use of biological agents in women of fertile age, the information was updated for the years 2006 and 2007. Experts disagree whether TNF-inhibitors should be stopped as soon as pregnancy is recognized or may be continued throughout pregnancy. Pregnancy experience with abatacept and rituximab is still too limited to prove their safety for the developing fetus. They must be withdrawn before a planned pregnancy. LEF has not been proven to be a human teratogen. Registries of transplant recipients have shown that cyclosporin (CsA) and tacrolimus do not increase the rate of congenital anomalies, whereas mycophenolate mofetil (MMF) clearly carries a risk for congenital anomalies. Prophylactic withdrawal of drugs before pregnancy is mandatory for abatacept, rituximab, LEF and MMF. Data remain insufficient for gonadal toxicity of immunosuppressive drugs in men and for excretion of these drugs in human breast milk.

Anticancer drugs from nature--natural products as a unique source of new microtubule-stabilizing agents

This review article provides an overview on the current state of research in the area of microtubule-stabilizing agents from natural sources, with a primary focus on the biochemistry, biology, and pharmacology associated with these compounds. A variety of natural products have been discovered over the last decade to inhibit human cancer cell proliferation through a taxol-like mechanism. These compounds represent a whole new range of structurally diverse lead structures for anticancer drug discovery.