Transgenic rat model of Huntington's disease

Huntington's disease (HD) is a late manifesting neurodegenerative disorder in humans caused by an expansion of a CAG trinucleotide repeat of more than 39 units in a gene of unknown function. Several mouse models have been reported which show rapid progression of a phenotype leading to death within 3-5 months (transgenic models) resembling the rare juvenile course of HD (Westphal variant) or which do not present with any symptoms (knock-in mice). Owing to the small size of the brain, mice are not suitable for repetitive in vivo imaging studies. Also, rapid progression of the disease in the transgenic models limits their usefulness for neurotransplantation. We therefore generated a rat model transgenic of HD, which carries a truncated huntingtin cDNA fragment with 51 CAG repeats under control of the native rat huntingtin promoter. This is the first transgenic rat model of a neurodegenerative disorder of the brain. These rats exhibit adult-onset neurological phenotypes with reduced anxiety, cognitive impairments, and slowly progressive motor dysfunction as well as typical histopathological alterations in the form of neuronal nuclear inclusions in the brain. As in HD patients, in vivo imaging demonstrates striatal shrinkage in magnetic resonance images and a reduced brain glucose metabolism in high-resolution fluor-deoxy-glucose positron emission tomography studies. This model allows longitudinal in vivo imaging studies and is therefore ideally suited for the evaluation of novel therapeutic approaches such as neurotransplantation.     

Heat shock protein 60 from Chlamydia pneumoniae elicits an unusual set of inflammatory responses via Toll-like receptor 2 and 4 in vivo

Heat shock protein 60 (HSP60) from Chlamydia pneumoniae was described to trigger in vitro inflammatory and cytokine responses including TNF and IL-12p40. Although it can be found in atherosclerotic plaques of patients, the stimulatory potential of chlamydial and other HSP60 in vivo is unclear. We now report that chlamydial HSP60 fails to induce TNF expression in vivo, and significant serum levels of IL-12p40 are only found upon intraperitoneal injection of high doses of HSP60 or after intravenous application. Upon purification of chlamydial HSP60 with polymyxin B-agarose columns, its ability to induce TNF secretion in vitro is much reduced. However, purified chlamydial HSP60 causes increased serum levels of the CXC chemokines KC and MIP2 in vivo, as well as a strong accumulation of polymorphonuclear neutrophils (PMN) in the peritoneal cavity upon intraperitoneal challenge. With respect to PMN accumulation, chlamydial HSP60 is more potent than endotoxin or the CpG oligonucleotide 1668. The responses observed are completely abolished in Toll-like receptor (TLR)2/4-double-deficient mice, while single-deficient mice respond almost normally. Furthermore, KC induction and PMN accumulation are largely dependent on MyD88. In conclusion, HSP60 from C. pneumoniae triggers inflammatory responses in vivo that differ from responses induced by endotoxin or CpG oligonucleotides and are dependent on TLR2 and 4.     

During hypoxic exercise some vasoconstriction is needed to match O2 delivery with O2 demand at the microcirculatory level.

To test the hypothesis that the increased sympathetic tonus elicited by chronic hypoxia is needed to match O(2) delivery with O(2) demand at the microvascular level eight male subjects were investigated at 4559 m altitude during maximal exercise with and without infusion of ATP (80 mug (kg body mass)(-1) min(-1)) into the right femoral artery. Compared to sea level peak leg vascular conductance was reduced by 39% at altitude. However, the infusion of ATP at altitude did not alter femoral vein blood flow (7.6 +/- 1.0 versus 7.9 +/- 1.0 l min(-1)) and femoral arterial oxygen delivery (1.2 +/- 0.2 versus 1.3 +/- 0.2 l min(-1); control and ATP, respectively). Despite the fact that with ATP mean arterial blood pressure decreased (106.9 +/- 14.2 versus 83.3 +/- 16.0 mmHg, P < 0.05), peak cardiac output remained unchanged. Arterial oxygen extraction fraction was reduced from 85.9 +/- 5.3 to 72.0 +/- 10.2% (P < 0.05), and the corresponding venous O(2) content was increased from 25.5 +/- 10.0 to 46.3 +/- 18.5 ml l(-1) (control and ATP, respectively, P < 0.05). With ATP, leg arterial-venous O(2) difference was decreased (P < 0.05) from 139.3 +/- 9.0 to 116.9 +/- 8.4(-1) and leg .VO(2max) was 20% lower compared to the control trial (1.1 +/- 0.2 versus 0.9 +/- 0.1 l min(-1)) (P = 0.069). In summary, at altitude, some degree of vasoconstriction is needed to match O(2) delivery with O(2) demand. Peak cardiac output at altitude is not limited by excessive mean arterial pressure. Exercising leg .VO(2peak) is not limited by restricted vasodilatation in the altitude-acclimatized human.     

Prolactin levels in paternal striped mouse (Rhabdomys pumilio) fathers

Paternal behavior is associated with an increase in prolactin levels in fish, birds and mammals, including rodents. The striped mouse (Rhabdomys pumilio) from southern Africa shows highly developed paternal care. We investigated whether striped mouse fathers have higher prolactin levels than nonfathers, and whether there is a relationship between tactile stimulation with pups and prolactin secretion in fathers. We measured serum prolactin in 42 male striped mice assigned to one of four different experimental groups (single males, paired males, fathers housed with mother and pups, and fathers separated from their family by a wire-mesh partition). Our results revealed no increases in prolactin levels in fathers, and fathers with tactile contact with pups did not have higher prolactin levels than the fathers that were prevented from making tactile contact with pups. In contrast, experienced males had higher prolactin levels than inexperienced males. Male striped mice are polygynous in nature, living in groups, with three breeding females, and are permanently associated with pups during the breeding season. In a field study, males had higher prolactin levels during the breeding season than during the nonbreeding season. Thus, prolactin secretion in the polygynous striped mouse might be regulated by environmental stimuli, whereas social stimuli might be important for monogamous species. This is the first study to demonstrate seasonal changes in prolactin levels in a free-living male mammal.     

Immunohistochemical and molecular analysis of p53, RB,and PTEN in malignant peripheral nerve sheath tumors

The molecular basis of both sporadic and neurofibromatosis type 1 (NF1)-associated malignant peripheral nerve sheath tumors (MPNSTs) is yet largely undetermined. Therefore, we analyzed a series of 12 MPNSTs - including two cases which arose in the setting of NF1 - for molecular alterations in the p53, retinoblastoma ( Rb), and PTEN tumor suppressor genes. Furthermore, the immunohistochemical expression of p53, RB, and PTEN protein was examined in these tumors. One mutation (8%), an A to T transversion leading to an amino acid exchange, was found in exon 5 of the p53 gene in a sporadic MPNST. In two other sporadic tumors (20%), loss of heterozygosity (LOH) of the p53 gene occurred. Nuclear overexpression of p53 protein was observed in ten tumors (83%). Loss of RB protein expression was seen in two MPNSTs (17%), and LOH of the Rb gene was detected in four tumors (44%), including the two NF1-associated MPNSTs, one of them showing concomitant loss of RB protein expression. No mutation in the PTEN gene was detected, and cytoplasmic immunoreactivity for the PTEN protein was maintained in eight MPNSTs (67%). We suggest that alterations in the p53 and RB pathway, both are essential in controlling the cell-cycle progression, are critical points in the tumorigenesis of sporadic and NF1-associated MPNSTs, whereas the PTEN gene seems to play no significant role in this process.     

Offshore telemedicine emergency service: a 1-year experience

Journal of Public Health - Offshore wind energy is a fast growing market. Accordingly, a correspondingly large number of employees are working at the wind farms. Owing to the harsh operating...     

Rapid rise in plasma glucagon induced by acute cold exposure in man and rat

The effect of acute cold exposure on the concentration of glucagon in the blood was investigated in man and in intact and adrenalectomized rats.In man fasted overnight acute cold exposure, which caused a twofold increase in O₂-consumption resulted in a rapid rise in plasma glucagon. The levels of insulin and blood glucose remained unaltered, while the concentration of serum free fatty acids and -hydroxybutyrate increased.In fasted intact rats acute cold exposure lead to similar effects. A close parallelism between the rise in plasma glucagon and the concentration of hepatic cycloAMP was observed. Adrenalectomy did not impair the cold induced rise in plasma glucagon and hepatic cycloAMP.It is concluded that acute cold exposure caused a rapid rise in the concentration of plasma glucagon leading to an increase in the concentration of hepatic cycloAMP, thus enhancing the rate of hepatic gluconeogenesis and ketogenesis. As these alterations were similar in the absence of glucocorticoids and medulla-derived catecholamines, it is suggested that glucagon may play a role in the metabolic adaptation to acute cold exposure.     

The use of trimeric isoleucine-zipper fusion proteins to study surface-receptor-ligand interactions in natural killer cells

The ligands for several activating natural killer (NK) cell receptors have not been identified to date. Soluble receptor fusion proteins can be used to stain target cells for the presence of these unidentified ligands. Here, we describe the generation and use of soluble type I NK cell receptor isoleucine-zipper (ILZ) fusion proteins of the immunoglobulin (Ig) superfamily. ILZ-fusion proteins are easy to produce and purify. They form trimeric complexes in solution and display a higher binding avidity than classical immunoglobulin-fusion proteins. ILZ-fusion proteins do not interact with Fc-receptors and can therefore be used to block receptor-ligand interactions in cellular assays. This makes ILZ-fusion proteins a valuable tool to study receptor-ligand interactions in NK cells and other cellular systems.     

The pharmacokinetics of high-dose epirubicin and of the cardioprotector ADR-529 given together with cyclophosphamide, 5-fluorouracil,and tamoxifen in metastatic breast-cancer patients

A high-pressure liquid chromatographic method for determination of the bisdioxopiperazine derivative ADR-529 (ICRF-187), a compound proven effective in protection against anthracycline-induced cardiotoxicity, has been developed. The limit of quantitation was 5 ng/ml using a narrow-bore 5-m silica column and UV detection. The method was used for determination of pharmacokinetic profiles of ADR-529 after a 3-weekly i.v. administration of different doses of ADR-529 (600–1000 mg/m²) together with different doses of epirubicin (E, 60–100 mg/m²), fixed-dose cyclophosphamide (C, 600 mg/m²), fixed-dose 5-fluorouracil (F, 600 mg/m²), and daily administration of tamoxifen (T, 30 mg; CEF-T) in the treatment of patients with metastatic breast cancer. Pharmacokinetic parameters for epirubicin were also determined. The aim of the study was to determine (1) whether the pharmacokinetics of ADR-529 as part of a combination with CEF-T changes with increasing doses of ADR-529 and increasing doses of epirubicin and (2) whether the pharmacokinetics of epirubicin in the same combinations is altered with the administration of increasing doses of ADR-529. A total of 82 patients were included. A crossover study including 16 of the patients showed no significant difference in epirubicin pharmacokinetic parameters when epirubicin was given with or without concomitant administration of ADR-529. Apart from minor changes in the distributional half-lives, the pharmacokinetic parameters of epirubicin were not altered with increasing doses of ADR-529, nor were the pharmacokinetic parameters of ADR-529 itself. Escalating doses of epirubicin did not significantly alter the pharmacokinetic parameters of ADR-529 with the exception of a 30% increase in the terminal half-life and a decrease in total body clearance when the epirubicin dose was raised from 60 to 100 mg/m². We conclude that concomitant administration of ADR-529 does not alter the distribution and elimination of epirubicin in doses suitable for preventing the anthracycline-induced cardiotoxicity.