Factors determining microbial colonization of liquid nitrogen storage tanks used for archiving biological samples

The availability of bioresources is a precondition for life science research, medical applications, and diagnostics, but requires a dedicated quality management to guarantee reliable and safe storage. Anecdotal reports of bacterial isolates and sample contamination indicate that organisms may persist in liquid nitrogen (LN) storage tanks. To evaluate the safety status of cryocollections, we systematically screened organisms in the LN phase and in ice layers covering inner surfaces of storage tanks maintained in different biobanking facilities. We applied a culture-independent approach combining cell detection by epifluorescence microscopy with the amplification of group-specific marker genes and high-throughput sequencing of bacterial ribosomal genes. In the LN phase, neither cells nor bacterial 16S rRNA gene copy numbers were detectable (detection limit, 10² cells per ml, 10³ gene copies per ml). In several cases, small numbers of bacteria of up to 10⁴ cells per ml and up to 10⁶ gene copies per ml, as well as Mycoplasma, or fungi were detected in the ice phase formed underneath the lids or accumulated at the bottom. The bacteria most likely originated from the stored materials themselves (Elizabethingia, Janthibacterium), the technical environment (Pseudomonas, Acinetobacter, Methylobacterium), or the human microbiome (Bacteroides, Streptococcus, Staphylococcus). In single cases, bacteria, Mycoplasma, fungi, and human cells were detected in the debris at the bottom of the storage tanks. In conclusion, the limited microbial load of the ice phase and in the debris of storage tanks can be effectively avoided by minimizing ice formation and by employing hermetically sealed sample containers.

[Cost analysis of telemedical treatment of stroke]

BACKGROUND

Telemedicine-enabled stroke networks increase the probability of a good clinical outcome. There is a shortage of evidence about the effects of this new approach on costs for inpatient care and nursing care.

METHODS

We analysed health insurance and nursing care fund data of a statutory health insurance company (AOK Bayern). Data from stroke patients initially treated in a TeleStroke network (TEMPiS - telemedical project for integrative stroke care) between community hospitals and academic stroke centres were compared to data of matched hospitals without specialised stroke care and telemedical support. Costs for nursing care were obtained over a 30-month period after the initial stroke. To rule out pre-existing differences between network and control hospitals, costs of stroke care were also analysed during a time period before network implementation.

FINDINGS

1 277 patients (767 in intervention, 510 in control hospitals) were analysed in the post-implementation period. An increased proportion of patients treated in intervention hospitals had a favourable outcome concerning the level of required nursing care. Patients in intervention hospitals had higher costs for acute inpatient care (5 309 € vs. 4 901 €, p=0.04), but lower nursing care fund costs (3 946 € vs. 5 132 €; p=0.04). There was no difference in relation to absolute total costs obtained in the post-implementation period. However, nursing care costs per survived year were significantly lower in intervention hospitals (1 953 € vs. 2 635 €; p=0.005). No significant differences were found in the pre-implementation period.

CONCLUSIONS

Considering both health insurance and nursing care fund costs, the incremental costs for TeleStroke network care in hospitals are compensated by savings in outpatient care.

[Acceptance of telemedicine for acute stroke care. The German project TEMPiS]

BACKGROUND

Telemedicine is increasingly used for acute stroke care, making neurological expertise available in nonspecialized hospitals. There are few data about telemedicine's acceptance by either medical staff or patients at treating hospitals.

METHODS

Telemedicine's acceptance was evaluated in the Telemedical Project for Integrative Stroke Care (TEMPIS), a network of two stroke centers and 12 community hospitals in the German state of Bavaria; the grading of teleconsultation regarding video and audio quality, time consumption, and medical relevance was assessed in two periods, 2004 and 2007. Overall satisfaction with in-hospital treatment was compared between patients in telemedically-linked hospitals with specialized stroke care and patients treated in conventional community hospitals. With regard to sufficient follow-up rates, ratings were restricted to patients living at home without severe disability at 3 months after stroke. A second evaluation analyzed how the parameter "Telemedical assessment of patient" (36% of patients in TEMPIS hospitals) affected overall satisfaction.

RESULTS

Respectively, 140 and 127 uses of telemedicine were assessed in the two evaluation periods. Video quality, time consumption, and medical relevance were graded "excellent" by over 50% in both periods. Audio quality was rated "excellent" by only 22% in the first period but 69% in the second. Excellent overall satisfaction was expressed significantly more frequently by patients at TEMPIS hospitals (total number 1044) than by those at control hospitals (total number 484; 56% vs 47% respectively, P<0.01). Patient consultation via telemedicine per se did not correlate with modified grading.

CONCLUSIONS

Acceptance of telemedicine in acute stroke care was high and stable over a long period. This study suggests improved overall satisfaction with treatment in hospitals offering specialized care and linked via telemedicine. Clinical assessment via telemedicine had no major effect on satisfaction.

[Improvement in stroke care in a non-urban community hospital--quality of procedures before and after participating in a telemedical stroke network]

BACKGROUND

Although treatment in a stroke unit has been proven to be effective, most stroke patients in rural areas have no access to it. The community hospital of Ebersberg (Bavaria/Germany) joined the Telemedic Project for Integrative Stroke Care (TEMPiS) in order to optimize the quality of stroke care. This analysis focuses on changes in stroke management using generally accepted indicators for quality of acute stroke treatment.

METHODS

The core elements consisted of the setting up of a stroke ward in the community hospital, continual stroke education and a 24-hour telemedical consultation service offered by stroke centers. Treatment of stroke patients was documented during two 12-months periods before the project was started start (i.e. retrospectively) and during the course of the project (prospectively). In addition, data on fatal outcome and institutionalization of patients who had lived at home before the qualifying event were collected 12 months after stroke onset.

RESULTS

There were 299 admissions for stroke or transient ischemic attacks between 1 Nov 2001 and 31 Oct 2002, and 305 between 7 July 2003 and 6 June 2004. Length of in-hospital stay decreased from 12.1 to 9.2 days. More patients (10.3 vs. 1.3%) were transferred to other acute hospitals during the later period. Indicators for stroke care quality improved: numbers of cerebral imaging rose from 56.5% to 96.4%, of duplex sonography of cervical arteries from 43.5 to 72.8 %, of speech therapy from 0% to 50.8% and of occupational therapy from 0 to 33.4%. One year after admission, 18.9% and 17.2%, respectively, of the patients had died, while 10.2% and 6.1% were living in institutions.

CONCLUSION

Participation in the TEMPiS network substantially improved stroke care quality according to national and international guidelines. These improvements may lead to a better prognosis after a stroke.

Problemfeld der Notfallverlegungen beim Schlaganfall

BACKGROUND

Specific stroke subtypes like subarachnoid hemorrhages or malignant brain infarcts require immediate interventions, but treatment options are offered mainly in specialized centers. For this reason, interhospital transfers from primary hospitals need to be done without delay.

METHODS

The telemedic pilot project for integrative stroke care (TEMPiS) connects 2 stroke centers and 12 regional hospitals in Bavaria (Germany). Core elements are the implementation of stroke wards, telemedic consultation and improvement of emergency interhospital transfers. Organization of patient transports is offered by the central telemedic service. During the first 12 months of the continuing project all interhospital transfers initiated by the central telemedic service were prospectively documented. Emergency transports were analysed according to diagnosis, type of transport, distance and time delays.

RESULTS

A total of 252 interhospital transfers were recommended in teleconsultations; finally 221 transports took place. Median total duration of transfers (including the necessary arrangements) was 134 min (interquartile range: 105-219) for intracerebral hemorrhages (N = 58), 138 min (95-157) for subarachnoid hemorrhages (N = 31), 161 min (100-230) for malignant infarcts (N = 22) and 147 min (109-180) for suspected basilar artery occlusion (N = 28). Time from admission in the primary hospital to initiation of interhospital transfer was 135 min (median; interquartile range: 86-172), transport time was 81 min (60-116). Helicopter transport did not save time for transfer distances up to 50 kilometres, compared to transport via ambulance (including assistance of hospital physicians). Transport using a special intensive care vehicle was much more time consuming because of the longer transport preparation time.

CONCLUSION

Emergency transfers of stroke patients are time consuming. This may contribute to additional harm being done to severely ill patients. Faster organization and conduct of transports is required.

The Hazard Analysis Critical Control Point's (HACCP) concept as applied to some chemical, physical and microbiological contaminants of milk on dairy farms. A prototype

Quality management on dairy farms becomes more and more important regarding the different areas of animal health, animal welfare and food safety. Monitoring animals, farm conditions and farm records can be extended with risk identification and risk management. The hazard analysis critical control point's system is useful as an on farm strategy to control the product as well as the production process on the areas of animal health, animal welfare and food safety. This article deals in detail with the question how to develop a qualitative method where risk can be defined as an interaction between probability and impact. Two parts of the production process (milk harvest and treatment of cows) where used as an example how to apply the hazard analysis critical control point's system on chemical, physical and microbiological contaminants of milk. Not just only by summarizing the different critical checkpoints for each area but also by giving them a precise judgement of probability and impact.

The Use of Telemedicine in Combination With a New Stroke-Code-Box Significantly Increases t-PA Use in Rural Communities

BACKGROUND

The benefit of tissue plasminogen activator (t-PA) is strongly associated with the time to treatment. In Bavaria, Germany, only half of the population has the opportunity to be transferred to 1 of the 19 stroke units within the critical time window of less than 3 hours. The aim of this study was to investigate the benefit of a new stroke-code-box for t-PA thrombolysis combined with a telemedicine network system to increase the use of acute stroke thrombolysis.

METHODS

Two specialized stroke centers in Germany established a 24-hour telemedicine network (Telemedicine Pilot Project of an Integrated Stroke Care [TEMPiS]) to advise 12 community hospitals in eastern Bavaria. These clinics are linked via telemedicine in a 24-hour/7-day service network that allows patients to be examined by experts via a videoconference system Additionally, a special stroke-code-box for acute t-PA thrombolysis was designed to reduce time in the application and documentation process.

RESULTS

In the 12-month period before implementation of the TEMPiS network system, 10 patients had received systemic thrombolysis. In our 6-month study period (from July to December 2003) and after implementation of a stroke-code-box for t-PA thrombolysis within the telestroke network, 164 patients with acute stroke were presented with t-PA treatment indications. Of this patient population, 27.4% (45 of 164) received t-PA.

CONCLUSIONS

Stroke care, including t-PA thrombolysis in non-urban areas, is feasible using a modern stroke unit concept within a telestroke network. With the expertise of specialized stroke centers accessed via telemedicine and the design of a stroke-code-box for t-PA thrombolysis, nearly one-third of patients presented with a possible indication for systemic thrombolysis can be treated with t-PA, thereby increasing the options for a successful stroke treatment.

Telemedizinisch vernetzte Schlaganfallstationen

More than 100 stroke units have been established in Germany. In rural areas, however, acute stroke care needs to be improved. In order to advance clinical stroke therapy, two specialized stroke centers founded a telemedicine network (TEMPiS) among 12 community hospitals in eastern Bavaria. Each network hospital established specialized stroke wards where qualified teams manage acute stroke patients. Twenty-four hours daily, physicians in local hospitals are able to contact the stroke centers via videoconferencing including transmission of digital DICOM data. To study the efficacy of this network, a controlled trial will be performed. Five TEMPiS-network hospitals will be matched with five other hospitals equal in size, catchment area, and diagnostic techniques. For about 1 year, all consecutive stroke cases in the matched study hospitals will be prospectively recorded in a database. Neurological deficits will be quantified on the National Institute of Health Stroke Scale within 24 h after stroke onset. Mortality and institutional care as a combined primary endpoint will be assessed after 3 and 12 months. Furthermore, functional outcome according to the modified Rankin scale, Barthel score, and quality of life will be assessed using a standard telephone interview. Data acquisition started in July 2003, and final results are expected in 2005.

R1--systemic thrombolysis in German stroke units--the experience from the German Stroke data bank

BACKGROUND

Systemic thrombolysis with tissue plasminogen activator (t-PA) for treatment of acute ischemic stroke was approved in Germany in 2000. Up to now, only data from single centers have been available for the study of the use of thrombolysis in a hospital-based approach outside controlled trials. We therefore sought to determine the frequency of application and complications as well as the patient outcome after t-PA treatment in clinical routine of specialized stroke centers in Germany.

METHODS

Within the German Stroke Data Bank Collaboration, 6234 consecutive patients with ischemic stroke were prospectively documented in 20 stroke centers between 1998 and 1999. The patients were centrally followed via telephone interview after 3 months and 1 year to assess global functional outcome using the Modified Rankin Scale.

RESULTS

250 patients (4 %) received systemic t-PA treatment during the study period. The baseline characteristics of these patients were comparable to large clinical trials and phase IV studies. Symptomatic and asymptomatic parenchymal hemorrhage occurred in 22 patients (8.8 %) and was fatal in 3 patients. Follow-up data after 3 months were obtained in 82.4 % of all patients, of which 35 % had a favorable functional outcome (mRS </= 1), while 23.8 % were severely disabled (mRS >/= 4) and 17 % had died.

CONCLUSION

The results of our study agree with the assumption that thrombolytic therapy can be performed safely and effectively in daily clinical practice. Nevertheless, the small proportion of patients receiving thrombolysis even in specialized stroke centers calls for further improvement of acute stroke management in Germany.

Therapeutic neutralization of CD95-ligand and TNF attenuates brain damage in stroke

Stroke is the third most common cause of death in the Western world. The mechanisms of brain damage in the affected areas are largely unknown. Hence, rational treatment strategies are limited. Previous experimental evidence suggested that cerebral lesions were less prominent in CD95 (APO-1/Fas)-deficient (lpr) than in wild-type mice. Additional results strongly suggested that the CD95-ligand (CD95L) was a major cause of neuronal autocrine suicide in the penumbra. These data and the assumption that death-receptor systems might determine stroke-related damage in the brain prompted us to examine these systems in in vitro and in vivo models of ischemia. We showed that hybrids of TNF-deficient and gld mice were strongly resistant towards stroke-induced damage. To determine the mechanism of action of TNF and CD95L, we separately investigated their influence on primary ischemic death and secondary inflammatory injury. Inhibition of both TNF and CD95L in vitro prevented death of primary neurons induced by oxygen-glucose deprivation and reperfusion. The recruitment of inflammatory cells to the ischemic hemisphere was abrogated in the absence of both TNF and CD95L. Significantly, mice injected with a mixture of neutralizing anti-TNF and anti-CD95L antibodies 30 min after induction of stroke showed a marked decrease in both infarct volumes and mortality. Accordingly, the locomotor performance of these animals was not significantly impaired in comparison to sham-operated animals. These data reveal that inhibition of TNF and CD95L blocks stroke-related damage at two levels, the primary ischemic and the secondary inflammatory injury. These results offer new approaches in stroke treatment.

Mouse mammary gland involution is associated with cytochrome c release and caspase activation

At weaning, milk producing mammary epithelial cells undergo apoptosis and are removed by phagocytosis. Here, we show that mouse mammary gland involution is associated with mitochondrial cytochrome c release and processing of numerous caspases, including caspase-1, -3, -7, -8 and -9. Induction of caspase-3-like activity paralleled cleavage of poly-(ADP--ribose) polymerase. Dexamethasone inhibited processing of caspase-3, -7 and -8 and apoptosis, but had no effect on caspase-1 accumulation and cytochrome c release. In Bcl-2 transgenic animals, cytochrome c release, caspase activation and apoptosis were impaired. Thus, the pro-apoptotic signaling pathway in mammary epithelial cells during involution involves the release of cytochrome c and activation of caspases. It is inhibited by Bcl-2 at the mitochondrial level and by dexamethasone at a post-mitochondrial level.

Involvement of CD95/Apo1/Fas in cell death after myocardial ischemia

BACKGROUND

The death of cardiac cells during ischemia and reperfusion is partially mediated by apoptosis, as seen, eg, in autopsy material of patients after acute myocardial infarction.

METHODS AND RESULTS

To study the role of CD95/Fas/Apo1 for induction of postischemic cell death, we used an ischemia/reperfusion model of isolated rat and mouse hearts in Langendorff perfusion. In this model, caspase-dependent apoptosis occurred during postischemic reperfusion. Moreover, soluble CD95 ligand/Fas ligand was released by the postischemic hearts early after the onset of reperfusion. In addition, this ligand was synthesized de novo under these circumstances. Similar findings were observed for other "death-inducing" ligands, such as tumor necrosis factor (TNF)-alpha and TNF-related apoptosis-inducing ligand. In primary adult rat myocyte culture, hypoxia and reoxygenation caused a marked increase in sensitivity to the apoptotic effects of CD95 ligand. Isolated hearts from mice lacking functional CD95 (lpr) display marked reduction in cell death after ischemia and reperfusion compared with wild-type controls.

CONCLUSIONS

These data suggest that CD95/Apo1/Fas is directly involved in cell death after myocardial ischemia. The CD95 system might thus represent a novel target for therapeutic prevention of postischemic cell death in the heart.

The immunophilin ligand FK506, but not GPI-1046, protects against neuronal death and inhibits c-Jun expression in the substantia nigra pars compacta following transection of the rat medial forebrain bundle

The immunophilin ligand FK506 (Tacrolimus) is used for prevention of graft rejection following organ transplantation. FK506 is a high-affinity ligand for FK506-binding proteins, an immunophilin subgroup of peptidyl-prolyl-cis/trans-rotamases abundant in the mammalian brain. Here, we demonstrate that FK506 is a potent survival factor that prevents neuronal cell death following axotomy of central intrinsic neurons. Administration of FK506 (2 mg/kg, s.c., per day for two days pre-axotomy and for up to eight days post-axotomy) effectively delayed and reduced the death of axotomized neurons in the substantia nigra pars compacta following transection of the medial forebrain bundle. In saline-treated controls, 75%, 89% and 92% of nigral neurons died after 25, 50 and 60 days post-axotomy, respectively. In contrast, application of FK506 resulted in survival of 46%, 44% and 28% of the axotomized nigral neurons, and the majority of these surviving neurons showed continuous expression of tyrosine hydroxylase, the pacemaker enzyme for dopamine synthesis. Moreover, FK506 significantly reduced the expression of the inducible transcription factor c-Jun and its N-terminal phosphorylation and prevented the axotomy-induced suppression of the constitutive transcription factor ATF-2 in neurons of the substantia nigra and mammillary body. The latter is also axotomized by the coincident transection of the mammillothalamic tract, but the mammillary neurons survive the axotomy. In contradistinction to FK506, the non-immunosuppressive FK506-binding protein ligand GPI-1046 (25 or 12.5 mg/kg, applied once or twice per day for two days pre-axotomy and for eight days post-axotomy) was completely ineffective for all these parameters investigated. Finally, FK506, but not GPI-1046, impressively accelerated the recovery from surgery. Our data provide the first evidence that FK506 acts as a neuroprotective molecule that rescues axotomized otherwise degenerating central intrinsic neurons in the adult mammalian brain by mechanisms that interfere with the transcriptional program of the axotomy-induced cell body response, such as activating transcription factor-2 suppression and c-Jun expression and phosphorylation.

Transient neuromotor phenotype in transgenic spastic mice expressing low levels of glycine receptor beta-subunit: an animal model of startle disease

Startle disease or hereditary hyperekplexia has been shown to result from mutations in the alpha1-subunit gene of the inhibitory glycine receptor (GlyR). In hyperekplexia patients, neuromotor symptoms generally become apparent at birth, improve with age, and often disappear in adulthood. Loss-of-function mutations of GlyR alpha or beta-subunits in mice show rather severe neuromotor phenotypes. Here, we generated mutant mice with a transient neuromotor deficiency by introducing a GlyR beta transgene into the spastic mouse (spa/spa), a recessive mutant carrying a transposon insertion within the GlyR beta-subunit gene. In spa/spa TG456 mice, one of three strains generated with this construct, which expressed very low levels of GlyR beta transgene-dependent mRNA and protein, the spastic phenotype was found to depend upon the transgene copy number. Notably, mice carrying two copies of the transgene showed an age-dependent sensitivity to tremor induction, which peaked at approximately 3-4 weeks postnatally. This closely resembles the development of symptoms in human hyperekplexia patients, where motor coordination significantly improves after adolescence. The spa/spa TG456 line thus may serve as an animal model of human startle disease.

The effect of proteolytic enzymes on hair follicles of transgenic mice expressing the lac Z-protein in cells of the bulge region

OBJECTIVE

To study the effects of proteolytic enzymes on mice hair follicles, particularly on cells of the bulge area regarded as follicle stem cells.

BACKGROUND

Previous application by iontophoresis of proteolytic enzymes on guinea pig skin resulted in degenerative effects on hair follicles and the hypothesis was proposed that some of the affected cells could be stem cells.

METHODS

To mark putative stem cells transgenic mice were produced carrying the lac-Z gene fused to the Upstream Regulatory Region (URR) of Human Papilloma Virus 11 (HPV11), as they express this gene specifically in the cells of the bulge area. Chymotrypsin and papain were applied on skin by iontophoresis, trypsin in the form of liposomes.

RESULTS

Enzyme application, both by electrophoresis and as liposomes, led to intense degenerative effects of the hair follicle, such as detachment of the inner root sheath, cystic dilation of the hair shaft and presence of epithelial cells within the lumen. Some of these cells represent hair follicle stem cells expressing beta-galactosidase (beta-gal), having been detached from the bulge area as a result of enzyme treatment, implying impairment of their function.

The human papillomavirus type 11 upstream regulatory region triggers hair-follicle-specific gene expression in transgenic mice

We have generated transgenic mice carrying the URR of the human papillomavirus type 11 ligated in front of the Escherichia coli beta-galactosidase coding region sequence. Using X-Gal staining to demonstrate beta-galactosidase production, we observed a hair-specific transcription of the reporter gene. This transcription was limited to the epithelial cells of the hair bulge region. The transgene was developmentally regulated, as no LacZ staining was demonstrated during embryogenesis and specific staining was first observed after birth. Surprisingly, dexamethasone and ultraviolet B, but not phorbol myristate acetate or progesterone treatment of the animals resulted in an increase in number and intensity of hair follicles expressing the reporter gene.

CD95 ligand (Fas-L/APO-1L) and tumor necrosis factor-related apoptosis-inducing ligand mediate ischemia-induced apoptosis in neurons

Programmed cell death plays an important role in the neuronal degeneration after cerebral ischemia, but the underlying mechanisms are not fully understood. Here we examined, in vivo and in vitro, whether ischemia-induced neuronal death involves death-inducing ligand/receptor systems such as CD95 and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). After reversible middle cerebral artery occlusion in adult rats, both CD95 ligand and TRAIL were expressed in the apoptotic areas of the postischemic brain. Further recombinant CD95 ligand and TRAIL proteins induced apoptosis in primary neurons and neuron-like cells in vitro. The immunosuppressant FK506, which most effectively protects against ischemic neurodegeneration, prevented postischemic expression of these death-inducing ligands both in vivo and in vitro. FK506 also abolished phosphorylation, but not expression, of the c-Jun transcription factor involved in the transcriptional control of CD95 ligand. Most importantly, in lpr mice expressing dysfunctional CD95, reversible middle cerebral artery occlusion resulted in infarct volumes significantly smaller than those found in wild-type animals. These results suggest an involvement of CD95 ligand and TRAIL in the pathophysiology of postischemic neurodegeneration and offer alternative strategies for the treatment of cardiovascular brain disease.

FK506 prevents stroke-induced generation of ceramide and apoptosis signaling

Ceramide is a key mediator of apoptosis during the cellular stress response which is also involved in stroke-induced death. Transient occlusion of the middle cerebral artery (MCA) in rats led to a strong generation of ceramide as measured in thalamus and entorhinal cortex of the ischemic brain tissue. Enhanced levels of ceramide may be involved in apoptosis signaling following stroke since exogenously added synthetic C2-ceramide increased expression of c-jun and the death-inducing ligands (DILs) CD95-L, TRAIL and TNF-alpha in neuroblastoma cells. DILs in turn mediated death via binding to their respective receptors as concluded from diminished apoptosis upon blocking of the common pathway by dominant negative FADD. C2-ceramide induced both necrosis and apoptosis in a concentration-dependent manner corresponding to the situation present in the ischemic brain. The immunosuppressant FK506 inhibited the release of ceramide, expression of CD95-L and apoptosis in an in vitro and in vivo model for ischemia/reperfusion. These data suggest that ceramide is a crucial initiator of death, e.g., by induction of DILs following stroke.

MAP kinase phosphatase 1 is expressed and enhanced by FK506 in surviving mamillary, but not degenerating nigral neurons following axotomy

The MAP kinase phosphatase 1 (MKP-1), a dual serine-threonine phosphatase, inactivates the MAP kinases ERK and JNK/SAPK which are involved in neuronal survival and neuronal cell death following injury and degenerative stimuli. We have studied by immunocytochemistry whether regulation of MKP-1 is part of the cell-body response following nerve fiber transection. The expression of MKP-1 was investigated in axotomized neurons of the corpus mamillaris (CMm) and substantia nigra pars compacta (SNC) following transection of the mamillo-thalamic tract (MT) and the medial forebrain bundle (MFB), respectively. In contrast to the surviving CMm neurons, the vast majority of SNC neurons undergoes cell death following axotomy. MKP-1 immunoreactivity which is absent in untreated adult rats, appeared in CMm neurons 24 h following MT transection, reached a maximum after 2 days and persisted in a substantial proportion of CMm neurons until 20 days, the end of observation period. In contradistinction, MKP-1 could not be detected in the SNC neurons. MKP-1 immunoreactivity was virtually restricted to the nuclei of neurons. Subcutaneous injection of the immunosuppressant FK506 that protects axotomized SNC neurons against neuronal cell death, enhanced the expression of MKP-1 in CMm, but failed to do so in SNC neurons. The selective expression of MKP-1 in CMm is the first finding on a different regulation of components in the stress kinase signal pathway in surviving vs. degenerating axotomized neurons.

Overexpression of Bcl-2 inhibits alveolar cell apoptosis during involution and accelerates c-myc-induced tumorigenesis of the mammary gland in transgenic mice

Expression of the apoptosis-inhibitory protein Bcl-2 has frequently been detected in human cancer including mammary carcinoma. The functional significance of its expression has been well established in experimental tumors of the lymphoid system, however, remains to be elucidated for epithelial tumors. In order to assess the role of Bcl-2 in mammary tumorigenesis we have generated WAP-bcl-2 transgenic mice. The strong overexpression of Bcl-2 in lactating mammary glands was preserved during early postlactational involution and apoptosis of alveolar epithelial cells was prevented without influencing the dedifferentiation of the milk-producing epithelium. Although Bcl-2 overexpression was not sufficient to induce spontaneous tumors it, however, led to an accelerated development of MMTV myc transgene-induced mammary tumors. In the mammary glands of MMTV myc transgenic mice, a high proportion of apoptotic cells was detected which was significantly reduced in the mammary glands of WAP-bcl-2/ MMTV myc double transgenic mice. Taken together, these results suggest that Bcl-2 contributes to mammary tumorigenesis by inhibiting apoptosis.

Low level expression of glycine receptor beta subunit transgene is sufficient for phenotype correction in spastic mice

Mutations in inhibitory glycine receptor (GlyR) subunit genes are associated with neuromotor diseases in man and mouse. To use the potential of the mouse mutants as animal models of human disease, we altered GlyR levels in mutant mice and studied their phenotype. A transgene coding for the beta subunit of the rat GlyR was introduced into the genetic background of the spa mutation, which is characterized by low endogenous expression levels of the beta subunit and a dramatic neuromotor phenotype. The resulting transgenic mice expressed the beta subunit mRNA at intermediate levels, and their phenotype was rescued. This provides formal proof for the casual relationship between GlyR beta gene mutation and motor disease, and indicates that a low level of beta gene expression (25% of normal) is sufficient for proper functioning of glycinergic synapses.

Functional rescue of the glomerulosclerosis phenotype in Mpv17 mice by transgenesis with the human Mpv17 homologue

The germ line insertion of a defective retrovirus into the Mpv17 gene of mice is associated with a recessive phenotype. Mice homozygous for the integration develop glomerulosclerosis at a young age. The phenotype resembles human glomerulosclerosis in its physiological parameters as well as in histology. A human homologue of the Mpv17 gene has been identified, isolated and analyzed. We here show that this gene, which has a role in the production of reactive oxygen species, can rescue the phenotype of Mpv17 deficient mice when introduced by transgenesis. This provides formal proof for the hypothesis that the phenotype is caused by the loss of function of the Mpv17 gene. It also provides evidence for the functional conservation of the Mpv17 gene in mammals and points to a potential role of this gene in human kidney disease.

Expression of interstitial collagenase during skeletal development of the mouse is restricted to osteoblast-like cells and hypertrophic chondrocytes

We determined the expression pattern of the matrix metalloproteinase interstitial collagenase (MMP-1) during mouse embryo development using in situ hybridization and immunohistochemistry. Localized MMP-1 mRNA was first detected at 14.5 days postconceptus. The spatial and temporal expression was restricted to areas of endochondral and intramembranous bone formation, such as in the mandibula, maxilla, clavicle, scapula, in the vertebrae, and in the dorsal, but not the ventral part of the ribs. The highest levels of MMP-1 transcripts and MMP-1 protein were found in the metaphyses and diaphyses of the long bones. MMP-1 was expressed by hypertrophic chondrocytes and by osteoblastic cells localized along the newly formed bone trabeculae. No expression was detected in osteoclasts. Two other related members of the MMP family, stromelysin-1 (MMP-3) and stromelysin-2 (MMP-10), were not expressed during days 7.5 and 16.5 of mouse embryogenesis. The tissue-specific expression of MMP-1 and the exclusive ability of interstitial collagenase to digest native collagen of types I, II, III, and X, the major components of bone, cartilage, and tendon, strongly suggests an important and specific function of this enzyme in bone development and remodeling.

Levels of peripheral T cell tolerance induced by different doses of tolerogen

Antigen-specific immunosuppression requires an understanding of the parameters that control peripheral T cell tolerance. A liver-specific inducible promoter was used to drive the expression of the major histocompatibility complex antigen Kb in transgenic mice. Minute amounts of Kb, expressed exclusively on hepatocytes, induced tolerance by partial down-regulation of the T cell receptor (TCR) on the self-reactive CD8+ cells. Contact of these tolerant T cells with high concentrations of Kb after induction led to complete down-regulation of TCR. Thus, tolerant T cells are susceptible to further tolerogenic signals and reach different levels of tolerance depending on antigen dose.

T cell activation and thymic tolerance induction require different adhesion intensities of the CD8 co-receptor

Activation of mature lymphocytes requires in addition to the TCR contact with the corresponding antigen the binding of the CD8 or CD4 co-receptors to MHC class I or class II proteins respectively. To investigate the contribution of the CD8-class I interaction to the elimination of autoreactive T cells during negative selection in the thymus we generated two types of transgenic mice. One set expressed a modified Kb molecule which contained a human HLA-A2 alpha 3 domain, thereby missing the binding residues for the murine CD8 molecules. The second set of mice expressed an anti-Kb specific TCR. Both lines were crossed and in the resulting double transgenic mice the development of Kb-reactive T cells was followed with an anti-clonotypic antibody. Surprisingly, efficient clonal deletion in the thymus was still observed, although the reduced CD8-class I adhesion abrogated effector functions in vivo and in vitro. These results imply that even T cells with intermediate affinity for self are negatively selected in the thymus despite the fact that they are not able to react against self antigens in the periphery. Thus a safety window is created which decreases the risk of autoaggression.

Isolation of HnRNP particles from Drosophila melanogaster embryos

HnRNP from nitrogen frozen Drosophila melanogaster embryos were isolated in the presence of EDTA and EGTA cosedimenting in sucrose and density gradients like hnRNP from vertebrates. Four "core" proteins of 23.000, 28.000, 32.000 and 45.000 Da are strongly enriched in these complexes. One could conclude that the basic structural organization of Drosophila melanogaster hnRNP is similar to that described for vertebrates.

T cell proliferation induced by monoclonal antibodies to a phosphatidylinositol-linked differentiation antigen of guinea pig lymphocytes

Monoclonal antibodies (mAb) to differentiation antigens frequently influence the in vitro function of antigen-bearing cells. We characterized a 32-36-kDa membrane protein expressed on guinea pig lymphocytes and Langerhans cells. A series of independently derived mAb to this protein, now called guinea pig T cell activation antigen (gpTAA), induced strong proliferation of T cells in vitro. Cross-linking of the mAb by a secondary antibody (rabbit anti-mouse Ig) and costimulation with phorbol 12-myristate 13-acetate were required for activation. Treatment of the cells with phosphatidylinositol-specific phospholipase C greatly reduced the amount of antigen expressed on the cell surface as measured by flow cytometry analysis. This finding indicates that the antigen is anchored to the cell membrane via phosphatidylinositol linkage as shown similarly for other membrane proteins with T cell activating properties, e.g. Thy-1 and Ly-6. The guinea pig protein differs, however, in its molecular weight and tissue distribution from similar proteins identified in the mouse or in the rat system. Unlike Thy-1, gpTAA is also expressed on B Lymphocytes and Langerhans cells. Considering the previously described involvement in cellular adhesion, and the functional characteristics reported here, gpTAA might represent a new species of differentiation antigen with T cell-activating capacity.

Production of antibodies to the constant region of the mouse T-cell-receptor beta-chain

To generate antibodies to the constant region of the mouse T-cell-receptor beta chain, the corresponding cDNA clone 86T5 was subcloned into the bacterial expression vector pEX2. The induced hybrid protein consisting of a 30 kDa T-cell-receptor segment and a beta-galactosidase carrier moiety was used for immunization. In Western blots using lysates of a T-cell-receptor-positive T-cell hybrid, the antisera obtained reacted with a 42 kDa protein under reducing and a 85 kDa protein under nonreducing conditions. The antisera did not react in binding assays with intact T lymphocytes, i.e. membrane-associated T-cell-receptor protein.

Bacteriophage T4 gene 32 protein shares antigen determinants with reconstituted HeLa hnRNP proteins in western blots

A polyclonal antiserum against purified bacteriophage T4 gene 32 protein was raised in rabbits. In Western blots it detected a number of SDS-PAGE separated nuclear and ribosomal proteins of HeLa cells. Using a renaturing blotting system, however, larger hnRNP proteins ranging between 66.000 and 82.000 Da preferentially reacted with this antiserum. In addition hnRNP group A core proteins were detected to a minor extent. Nucleic acid binding proteins like histones or ribosomal proteins were not stained by this antibody after renaturation.

Fluorescence studies on the role of tryptophan in heterogeneous nuclear ribonucleoprotein particles of HeLa cells

The 40 S heterogeneous nuclear ribonucleoprotein (hnRNP) particles from HeLa cells reveal tryptophan fluorescence with a bi-exponential decay, indicating that only a few of the 'core' proteins contain tryptophan residues. The presence of tryptophan residues distinguishes hnRNP particles from nucleosomes, with which they otherwise share a number of properties. This difference, however, is not essential for protein-RNA binding, as the fluorescence decay remains unchanged when hnRNP particles are dissociated into protein and RNA. However, the Stern-Volmer quenching constant is doubled upon salt dissociation, i.e. tryptophan residues become more accessible to solvent. Thus tryptophan quenching is a useful parameter for monitoring protein-protein interactions in hnRNP particles.

In vitro reconstitution of hnRNP particles

The assembly of hnRNP-like particles was studied by in vitro reconstitution, UV-crosslinking and CsCl-equilibrium centrifugation. Using total nuclear protein and RNA extracts from HeLa cells for RNP reconstitution, RNP particles sedimenting with the same buoyant density of p = 1.4 g/cm3 as 'native' 40 S core hnRNPs were obtained. Under the stringent reconstitution conditions used, hnRNP complexes containing only the Cl-core hnRNP protein could be identified.

Analysis of guinea pig leukocyte antigens using interspecies T cell hybrids

In the guinea pig system, there are no T lymphocyte tumors available. In addition, in this species the production of T cell lines in vitro for analysis of T cell markers or function proved to be difficult. As an alternative approach, guinea pig X mouse and guinea pig X rat T cell hybridomas were obtained by fusion of guinea pig T cells with HAT-sensitive mouse or rat thymomas. In ten fusions a total of 578 hybrids were produced and kept in culture for periods ranging from weeks up to several months. The highest yield was obtained when the Mb C 12 line was used as tumor parent. BW 5147 and the rat thymoma W/Fu(C58NT)D gave slightly lower fusion efficiencies. The yield depended also on the pretreatment of the parental cells. Activation by MLR proved to be most effective. A number of interspecies hybrids expressed guinea pig T cell differentiation antigens as detected by a cell ELISA. The positive hybrids were recloned several times and exhibited a stable expression of these markers, even after continuous culture for more than 2 months. Western blot analysis was used to confirm antigen expression at the protein level by comparing the hybrids with both parental cells. The hybrids expressed the proteins of the guinea pig lineage. No reaction was observed with the murine or rat thymomas. Therefore, the application of interspecies T cell hybrids provides an alternative for studies of guinea pig T cells. The cells are easy to grow and to clone and may be stored frozen in liquid nitrogen. The hybrids should permit analysis at the clonal level also for functional studies.

[New aspects of the pathogenesis of cardiovascular diseases]

While a detailed understanding of the molecular mechanisms of the pathogenesis of arteriosclerosis has not been forthcoming until now, considerable progress has been made in several important areas of the biology of the arterial wall. Progress was mainly accomplished by the use of tissue culture and techniques of molecular biology. Focuses of current interests are the roles of endothelium and of white blood cells, the properties and biological activities of growth factors, and the function of oncogenes.

RNA-binding properties of hnRNP proteins

The RNA-binding properties of the hnRNP monoparticle proteins were examined using a renaturing blotting procedure. All 'core' proteins are able to bind single-stranded nucleic acids, probably not sequence-specific. The core proteins C1 and, in one case A2 and B2, are able to bind nucleic acids which are double-stranded or which show a high degree of base-paired regions, among them U1 snRNA, whereas A1, B1 and C2 are unable to bind base-paired nucleic acids. The characteristics of C1 in binding base-paired nucleic acids are especially interesting, since the involvement of C1 in the splicing process has been described.