HIV-1 Nef protein exhibits structural and functional similarity to scorpion peptides interacting with K+ channels.

The persistent infection of human glial cells with HIV-1 is characterized by prominent expression of the Nef protein. In order to evaluate the possible role of Nef in the development of HIV-1-associated neurological disorders, we compared Nef with known neuroactive proteins. We found that HIV Nef shares sequence and structural features with scorpion peptides known to interact with K+ channels. Sequence similarity encompasses two distinct regions of scorpion peptides. Based on crystallography data, both regions in scorpion peptides cooperate in forming a common domain stabilized by ion pairs between charged amino-acid residues. Recombinant Nef protein, as well as a synthetic part of a scorpion channel active peptide (M10), reversibly increased the total K+ current of chick dorsal root ganglions in patch-clamp experiments without killing the cells. These results indicate that a region conserved in HIV Nef and scorpion peptides concurs in both structure and electrophysiological activity and suggest that Nef, like scorpion peptides, may affect neuronal cell function.     

Addition von Nucleophilen an 5-Desazaflavine,Teil 1

Addition of Nucleophiles to 5-Deazaflavins, Part 1 The reactivity of 5-deazaflavins and 5-deazaflaviniumsalts againts nucleophiles such as hydride-, dithionite-, sulfite- and cyanide ions as well as carbanions is described. The addition takes place in the 5-position and is in much cases reversible with acid. The title-compounds behave, as shown in photoreactions⁵), as “flavin-shaped nicotinamide models”. Side reactions and reoxidation of the adducts are discussed.     

Different proliferative activity of the glandular and myoepithelial lineages in benign proliferative and early malignant breast diseases.

The aim of the present study was to explore cell biological characteristics of normal breast, benign proliferative breast diseases and noninvasive breast malignancies based on the recently published adult progenitor cell concept from our group. Here, we investigated the proliferative activity of CK5/14(+), CK8/18/19(+) and alpha-smooth muscle actin(+) cellular phenotypes encountered in normal mammary gland, in a series of usual ductal hyperplasias and early malignant breast diseases, such as atypical ductal and lobular hyperplasias, as well as ductal and lobular in situ carcinomas. Immunohistochemical double labeling was performed on frozen sections from diagnostic breast biopsies by using antibodies to basal cytokeratins (CK5/14), glandular cytokeratins (CK8/18/19), smooth muscle actin and the Ki-67 antigen (MIB1). Normal breast tissues and usual ductal hyperplasias were characterized by a heterogeneous cellular composition of the growth fraction. The proliferative cell compartment consisted of CK8/18/19(+) glandular and, in a variable proportion, CK5/14(+) progenitor phenotypes. In contrast, noninvasive breast malignancies were composed of a monotonous proliferation of CK 8/18/19(+) neoplastic glandular cells. These findings indicate a significant role of progenitor cells in the development of benign proliferative breast diseases and lend support to the view that malignant transformation in the human breast usually occurs in a cell committed to the glandular lineage. Our results provide cell kinetic support to the functional progenitor cell hypothesis, and we propose this concept as an operative model for understanding benign proliferative and malignant breast diseases.     

Chromosomal imbalances in clear cell ependymomas.

Clear cell ependymoma is a rare and diagnostically challenging subtype of ependymoma, whose genetic features are essentially unknown. We studied 13 clear cell ependymomas (five cases WHO grade II, eight cases WHO grade III) by comparative genomic hybridization (CGH). Chromosomal imbalances were found in 12/13 cases. The most common aberrations overall were +1q (38%), -9 (77%), -3 (31%), and -22q (23%). Clear cell ependymomas of WHO grade II were characterized by -9 (40%), whereas WHO grade III cases mainly showed +1q (63%), and +13q (25%), as well as -9 (100%), -3 (38%), and -22q (25%). In contrast to other ependymal tumors, clear cell ependymomas of WHO grade II showed fewer imbalances than WHO grade III samples (1.4 vs 3.5 per case). Although some of the implicated chromosomes have previously been shown to be involved in other ependymoma variants, the striking frequency of +1q, -9, and -3 suggests that aberrations differ between clear cell and other types of ependymomas, in particular, for loss of chromosome 9 which can be regarded as the molecular hallmark of clear cell ependymomas.     

Tetrahydrobiopterin Attenuates Microvascular Reperfusion Injury Following Murine Pancreas Transplantation

In this study we investigated the effect of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide synthases, on ischemia-reperfusion injury (IRI) following murine pancreas transplantation. Pancreatic grafts were exposed to prolonged cold ischemia times (CIT) and different treatment regimens: normal saline (S), S + 16 h CIT, BH4 50 mg/kg + 16 h CIT. Nontransplanted animals served as controls. Graft microcirculation was analyzed by means of functional capillary density (FCD) and capillary diameters (CD) after 2 h reperfusion using intravital microscopy. Quantification of inflammatory responses (mononuclear infiltration) and endothelial disintegration (edema formation) was done by histology (hematoxylin and eosin), and peroxynitrite formation assessed by nitrotyrosine immunostaining. FCD was significantly reduced after prolonged CIT, paralleled by increased peroxynitrite formation as compared with controls (all p < 0.05). Microcirculatory changes correlated significantly with intragraft peroxynitrite generation (Spearman: r = -0.56; p < 0.01). Pancreatic grafts treated with BH4 displayed markedly higher FCD values (p < 0.01) and abrogated nitrotyrosine staining (p = 0.03). CD were not significantly different in any group. Histology showed increased inflammation, interstitial edema, hemorrhage, acinar vacuolization and focal areas of necrosis after 16 h CIT, which was diminished by BH4 administration (p < 0.01). BH4 treatment significantly reduces post-ischemic deterioration of microcirculation as well as histologic damage and might be a promising novel strategy in attenuating IRI following pancreas transplantation.     

Narcotic reversal in hypercapnic dogs: comparison of naloxone and nalbuphine

Reversal of opioid effects by naloxone (NX) can lead to significant cardiovascular problems. We have reported previously that hypercapnic dogs develop greater increases in blood pressure and plasma catecholamine (CA) levels than hypocapnic ones when reversed with naloxone. We have also demonstrated differences between NX and nalbuphine (NBPH) in producing excitatory adrenergic responses when administered during normocapnia. The present study was designed to investigate possible dissimilarities in cardiovascular and sympathetic events after administration of either NX or NBPH in dogs made hypercapnic following fentanyl administration. After induction of anaesthesia with thiopentone and intubation, two groups of dogs were maintained with controlled ventilation on enflurane in oxygen anaesthesia and given 50 micrograms.kg-1 fentanyl IV. This caused a significant decrease in heart rate (HR) (P less than 0.001), mean arterial blood pressure (MAP) (P less than 0.001), and plasma concentrations of norepinephrine (NE) (P less than 0.002). Then, ventilation was decreased to produce a PaCO2 of 60 mmHg; this was accompanied by a significant elevation in plasma level of both epinephrine (EPI) (P less than 0.02) and NE (P less than 0.001). Administration of 20 micrograms.kg-1 NX to six dogs resulted in immediate increases in HR (P less than 0.01) and MAP (P less than 0.01), and a further rise in CA levels to greater than pre-fentanyl baseline values. In six other dogs, NBPH (0.3 mg.kg-1) caused increases in HR (P less than 0.001) and MAP (P less than 0.001) only, and the MAP rise was significantly less than that seen in the NX group (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Insulin regulates the 35 kDa IGF binding protein in patients with diabetes mellitus

The serum levels of the low molecular form of insulin-like growth factor binding protein (IGFBP) was determined in 56 outpatients with diabetes mellitus by a radioimmunoassay developed for amniotic 35 kDa IGFBP. The mean level of 35 kDa IGFBP was found to be threefold higher in insulin dependent diabetes mellitus (IDDM), 112 +/- 13 ng/ml, than in age matched controls, 37 +/- 2 ng/ml, while the mean level in non-insulin dependent diabetes mellitus (NIDDM), 16 +/- 2 ng/ml, was decreased. In hospitalized IDDM patients there was a significant correlation (r = 0.91, p less than 0.01) between fasting blood-glucose and 35 kDa IGFBP levels, not found in NIDDM patients. During insulin infusion the 35 kDa IGFBP levels declined with a half-life of 60-120 min. The decline in IGFBP continued even after the establishment of steady state B-glucose at 4.7 mmol/l. In conclusion, the elevated 35 kDa IGFBP levels in IDDM can be attributed to insulin deficiency and may reflect a reduced bioavailability of the IGFs at the target cells.     

The acceleration transducer – an assessment of its precision in comparison with a force displacement transducer

A new and simple acceleration transducer (ACT)–based system of neuromuscular monitoring has recently been introduced. The precision of this transducer has been evaluated as compared to a conventional force displacement transducer (FDT) in the present study. Ten progressions of spontaneous recovery from atracurium–induced block with simultaneous measurements using the ACT on one hand and the FDT on the other were studied. Five individuals undergoing elective surgery in modified neurolept anaesthesia and one ICU–patient requiring prolonged neuromuscular blockade, sedated with pentobarbital, were included. Measurements were carried out on the latter patient on 5 consecutive days. Train–of–four (TOF) stimulation was used, readings were given in twitch heights (TH) (Tl/control value), and when four responses were obtained in TOF–ratios (T4/T1). Linearity was achieved after logit–transformation and the values regressed on time for each progression of recovery. Analysis of variance was applied to the regressions for the TH and TOF–ratio readings of each transducer. No significant differences were found, either between variation due to differences between slopes or variation due to technical error between the two transducers. The study indicates that the ACT is equal to the FDT with regard to precision in clinical recordings on atracuriumrelaxed individuals.     

Pharmacogenetic screening and therapeutic drugs.

BACKGROUND: Pharmacogenetics is the science of the influence of heredity on pharmacological response. ISSUES: The cost of severe adverse drug reactions in individuals has been estimated in the US alone to be in excess of US$4 billion. It has been argued that in a significant proportion of cases, the efficacy and toxicity profiles of drug therapy would be substantially improved in individuals if characteristics due to genetic variation were taken into account. Methods are now available, which make screening for susceptibility feasible. CONCLUSIONS: There are several therapeutic areas in which screening may give rise to significant improvements in outcome with cost-benefits to both the individual and the community. However, there is currently a lack of data on which cost-benefit analysis can be based. The challenge is to provide this information for new drugs, and for drugs with established therapeutic roles.