Lower adrenocortical and adrenomedullary responses to hypoglycemia in premenopausal women with systemic sclerosis

OBJECTIVES: To evaluate function of the hypothalamic-pituitary-adrenal (HPA) axis, adrenomedullary hormonal system (AMHS), and sympathetic noradrenergic system (SNS) in premenopausal women with systemic sclerosis (SSc). METHODS: Insulin-induced hypoglycemia (0.1 IU/kg) was performed in 17 longterm, glucocorticoid-naive SSc patients with low disease activity and in 18 healthy women matched for age and body mass index (BMI). Concentrations of glucose, adrenocorticotrophic hormone (ACTH), cortisol, androstenedione (ASD), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), 17a-hydroxyprogesterone (17OHP), epinephrine (EPI), norepinephrine (NE), interleukin 1ss (IL-1ss), IL-6, and tumor necrosis factor-a (TNF-a) were analyzed in plasma. RESULTS: Basal plasma levels of cortisol, ASD, 17OHP, DHEAS, IL-1ss, IL-6, and TNF-a were not significantly different in SSc compared to controls. Patients had higher basal ACTH (6.76 +/- 1.0 pmol/l in SSc vs 4.14 +/- 0.45 pmol/l in controls; p < 0.05), lower basal DHEA (9.02 +/- 1.64 nmol/l in SSc vs 17.0 +/- 2.8 nmol/l in controls; p < 0.05), and lower basal NE (1.61 +/- 0.26 nmol/l in SSc vs 2.57 +/- 0.38 nmol/l in controls; p < 0.05). Patients had comparable responses of glucose and ACTH to hypoglycemia. General linear model for repeated measurements, with BMI and age as covariates, revealed that the responses of 17OHP (p < 0.05), ASD (p < 0.05), DHEA (p < 0.01), EPI (p < 0.001), and NE (p < 0.001) to hypoglycemia were lower in SSc compared to controls. Cortisol response to hypoglycemia tended to be lower in SSc patients (p = 0.06) compared to controls. CONCLUSION: Our data indicate decreased adrenocortical and adrenomedullary functions in premenopausal women with SSc. Whether the observed changes in the neuroendocrine system are secondary to chronic disease deserves further investigation.     

Expression of a truncated tau protein induces oxidative stress in a rodent model of tauopathy

Truncation of tau protein and oxidative stress have been implicated as important pathogenetic events in tauopathies including Alzheimer's disease (AD). We have generated a transgenic rat model that expresses a human truncated tau protein analogous to a variant form derived from sporadic AD. We employed this model to investigate the relationship between tau protein truncation and oxidative stress. We have found that rat cortical neurons (derived from transgenic animals) that had been cultured in vitro for 16 days showed an increased accumulation of reactive oxygen species (up to 1.4-fold increase; P < 0.01) when compared to neurons derived from nontransgenic control animals. Transgene-expressing neurons treated with inducers of oxidative stress, such as glucose oxidase (GO) and buthionine sulfoximine (BSO), displayed dramatically reduced survival (31.4 +/- 3.3 and 24.9 +/- 3.6%, respectively; both P < 0.001) compared to neurons from control animals (79.9 +/- 7.1%, survival following treatment with GO and to 98.2 +/- 3.8%, survival following treatment with BSO). The number of mitochondria in processes of neurons from transgenic animals was decreased by about one-third from that present in neurons from control animals. The results reveal that expression of a human truncated variant form of tau protein leads to the accumulation of reactive oxygen species and sensitizes rat cortical neurons to cell death induced by oxidative stress. This indicates that truncation of tau may precede oxidative stress in the pathogenesis of neurodegenerative diseases such as AD and other tauopathies. These findings may have implications for therapeutic strategies aiming at prevention of neurofibrillary degeneration and cognitive decline, and identify potential new targets for drug development.     

Synthesis and antibacterial activity of isomeric 15-membered azalides

A series of 3-keto and 3-O-acyl derivatives of both 6-O-alkyl-8a-aza-8a-homoerythromycin A and 6-O-alkyl-9a-aza-9a-homo-erythromycin A were synthesised and tested against Gram-positive and Gram-negative bacteria. Derivatives of 8a-aza-8a-homoerythromycin A have potent antibacterial activity against not only azithromycin-susceptible strains, but also efflux (M) and inducible macrolide-lincosamide-streptogramin (iMLSB) resistant Gram-positive pathogens, while the corresponding 9a-isomers were less active. Introduction of an additional ring such as 11,12-cyclic carbonate reduced antibacterial activity of both series. 3-Keto and 3-O-(4-nitrophenyl)-acetyl derivatives of 6-O-methyl-8a-aza-8a-homo-erythromycin A show typical macrolide pharmacokinetics in preliminary in vivo studies in mice, and their in vivo efficacy is demonstrated.     

Semisynthetic macrolide antibacterials derived from tylosin. Synthesis and structure-activity relationships of novel desmycosin analogues

A series of 20-O-substituted and 3,20-di-O-substituted derivatives of desmycosin were synthesized and their biological properties were evaluated. In particular, we have synthesized numerous side chain modified analogues of desmycosin as well as some analogues possessing a combination of modified side chain and alternative C-3 substituents. Thus, alpha,beta-unsaturated analogues of desmycosin (2), tylosin (1), 10,11,12,13-tetrahydrotylosin (11), and 2,3-didehydrodesmycosin (13) were prepared from the corresponding aldehydes by a Wittig reaction with the stabilized ylides (a-d), generating a trans-double bond, followed by modified Pfitzner-Moffat oxidation of the C-3 hydroxyl group. To evaluate the importance of the C-3 position of desmycosin for biological activity, the C-3 substituted derivatives were synthesized by a standard sequence of protective group chemistry followed by Wittig reaction and esterification as the key steps. For the attachment of the C-3 ester functionality, a mixed anhydride protocol was adopted. Reaction proceeded smoothly to give corresponding esters in yields ranging from 70 to 80%. Base- and acid-catalyzed rearrangement products including desmycosin 8,20-aldols (24a and 24b) and desmycosin 3,19-aldol (25) are also described. Parallel array synthesis and purification techniques allowed for the rapid exploration of structure-activity relationships within this class and for the improvement in potency. In vitro evaluation of these derivatives demonstrated good antimicrobial activity against Gram-positive bacteria for most of the compounds. The present derivatives of 16-membered macrolides were active against MLS(B)-resistant strains that were inducibly resistant, but not those constitutively resistant to erythromycin.     

Combined Thalidomide and Temozolomide Treatment in Patients with Glioblastoma Multiforme

OBJECTIVES: Glioblastoma multiforme (GBM) may potentially be responsive to antiangiogenic therapies as these tumors are highly vascularized and overexpress angiogenic factors. Thalidomide exhibits antiangiogenic activity and may provide additive or synergistic antitumor effects when given concurrently with temozolomide, an alkylating agent. To further evaluate this new concept of combining an antiangiogenic with an alkylating agent, efficacy and tolerability of thalidomide alone and in combination with temozolomide were explored in a single-institution, nonrandomized open-label phase II study. PATIENTS AND METHODS: Forty-four patients with GBMs, who received thalidomide for a period of at least three months, were evaluated for survival, time to tumor progression (TTP), and side effects. Microsurgical tumor extirpation and radiotherapy preceded chemotherapy. Nineteen patients (43%) received thalidomide only (T), and 25 patients (57%) had a combined chemotherapy of thalidomide and temozolomide (TT). Median thalidomide dosage was 200 mg/day. Median temozolomide dosage was 200 mg/m2/day for five days, in monthly cycles. Neuroradiological outcomes were assessed by a semiquantitative grading system. RESULTS: Median survival was 103 weeks (95% CI, 65-141 weeks) for TT-patients and 63 weeks (95% CI, 49-77 weeks) for T-patients (p < 0.01). Median TTP for the TT-group was 36 weeks (95% CI, 20-52 weeks) and 17 weeks (95% CI, 13-21 weeks) for the T-group (p < 0.06). Neuroradiologically, 14 patients (56%) of the TT-group and six (32%) of the T-group had evidence of stable disease on at least two successive neuroradiological follow-ups. Progressive disease was found in nine patients (36%) of the TT-group and in 13 (68%) of the T-group. In two patients (8%) of the TT-group, a response with tumor regression was found. Thalidomide and concurrent temozolomide were safe and well tolerated with mild to moderate toxicities. CONCLUSIONS: The combination of thalidomide and temozolomide in the treatment of GBM appears to be more effective than that of thalidomide alone with respect to survival, TTP, and neuroradiological documentation of progression, stable disease or response. Further concurrent prospective studies of these agents in a larger group of patients with GBM will be required to establish the soundness of these intriguing observations.     

Genetic polymorphisms in DNA repair genes and possible links with DNA repair rates, chromosomal aberrations and single-strand breaks in DNA

We analysed the associations between genetic polymorphisms in genes coding for DNA repair enzymes XPD (exon 23 A --> C, K751Q), XPG (exon 15 G --> C, D1104H), XPC (exon 15 A --> C, K939Q), XRCC1 (exon 10 G --> A, R399Q) and XRCC3 (exon 7 C --> T, T241 M) and the levels of chromosomal aberrations (CAs) and single-strand breaks (SSBs) in peripheral lymphocytes in a central European population. We also measured the irradiation-specific DNA repair rates and the repair rates of 8-oxoguanines in these individuals. An elevated frequency of CAs was observed in individuals with the XPD exon 23 A allele (AA and AC) genotypes (F = 3.6, P = 0.028, ANOVA). In multifactorial analysis of variance, the XPD exon 23 polymorphism appeared as a major factor influencing CAs (F = 4.2, P = 0.017). SSBs in DNA, on the other hand, were modulated by XPD (F = 4.3, P = 0.023), XPG (F = 4.3, P = 0.024) and XRCC1 genotypes (F = 3.0, P = 0.064). Irradiation-specific DNA repair rates (reflecting mainly base excision repair activity) were affected by XRCC1 (F = 5.9, P = 0.010) and XPC polymorphisms (F = 4.2, P = 0.046, MANOVA). Our results from this study suggest that markers of genotoxicity are associated with polymorphisms in genes encoding DNA repair enzymes.     

Inactivation of HTB63 human melanoma cells by irradiation with protons and gamma rays

The effects of single irradiation with gamma rays and protons on HTB63 human melanoma cell growth were compared. The exponentially growing cells were irradiated with gamma rays or protons using doses ranging from 2-20 Gy. At 48 h of post-irradiation incubation under standard conditions, cell survival and induction of apoptotic cell death were examined. The best effect of the single irradiation with gamma rays was the reduction of cell growth by up to 26% (p=0.048, irradiation vs. control), obtained using the dose of 16 Gy. The same doses of proton irradiation, having energy at the target of 22.6 MeV, significantly inhibited melanoma cell growth. Doses of 12 and 16 Gy of protons provoked growth inhibition of 48.9% (p=0.003, irradiation vs. control) and 51.2% (p=0.012, irradiation vs. control) respectively. Irradiation with 12 and 16 Gy protons, compared to the effects of the same doses of gamma rays, significantly reduced melanoma cell growth (p=0.015 and p=0.028, protons vs. gamma rays, respectively). Estimated RBEs for growth inhibition of HTB63 cells ranged from 1.02 to 1.45. The electrophoretical analyses of DNA samples and flow cytometric evaluation have shown a low percentage of apoptotic cells after both types of irradiation. The better inhibitory effect achieved by protons in contrast to gamma rays, can be explained considering specific physical properties of protons, especially taking into account the highly localized energy deposition (high LET).