Circadian rhythm and whole gut transit in mice

BACKGROUND

In preclinical studies whole gut transit (WGT) in mice is a gold-standard "leading-edge" approach that measures the time between orogastric gavage of carmine red and defecation of the first carmine red pellet. Transit studies in humans are performed during the active day because GI motility and transit are suppressed during the night. Since mice are nocturnal, WGT studies traditionally done during the day occur during their rest phase. How circadian rhythm affects WGT in mice is not known.

METHODS

We used an automated approach for high temporal resolution uninterrupted testing of mouse WGT and activity. We housed wild-type Bl6/C57 mice under the standard 12 h light-dark cycles. At 8 weeks, we performed carmine red orogastric gavage and assessed WGT during Light (rest) conditions. Then, we exposed mice to a reverse 12 h light-dark cycle for 2 weeks and tested them in the Dark (active) under red light conditions. Timelapse videos were analyzed to quantify activity and to timestamp all pellets, and multiple parameters were analyzed.

KEY RESULT

When complementary light cycle reversal experiments were performed, we found a significant increase in mouse activity when mice were tested during their Dark (active) phase, compared to their Light (rest) phase. In mice tested in the Active phase compared to the Rest phase, we found a significant acceleration in WGT, increased rate and total number of pellets produced, and more pellet clustering. These data show that the mice tested in the Active phase have important differences in activity that correlate with multiple alterations in gastrointestinal transit.

CONCLUSION & INFERENCES

During the Active phase mice have faster WGT, produce more pellets, and cluster their output compared to testing in the Rest phase. Like in humans, circadian rhythm is an important consideration for transit studies in mice, and a simple reverse light cycle approach facilitates further studies on the role of circadian rhythm in GI motility.

Value of stomach content in a case of fatal child homicide

In death investigations, the volume of gastric contents may be useful concerning the time of death estimation, or to clarify the circumstances of death. Here, the case of a 4-month-old male infant who was found dead in his mother's bed is presented. SIDS was assumed as the cause of death after initial police investigations. Later, autopsy results revealed that this case was a homicide due to extensive abusive head trauma. The infant had three skull fractures on the back of his head with subdural hemorrhage and cerebral oedema. The survival time after feeding him formula and corresponding the time of death was determined to evaluate the mother's initial claims that the infant was alive several hours after feeding. In this case, the volume of stomach contents of the last meal was known. From the volume of milky fluid found in the stomach at autopsy, it was possible to estimate the time of death within a narrow time frame of less than one hour after feeding. The mother's claims could be ruled out, and she later confessed to having killed the child soon after feeding him. Even methods with low precision for estimating time of death, like examining stomach contents, can be essential for solving practical cases. To our knowledge, this is one of the first published cases in which an infant's stomach content was used successfully in the reconstruction of a homicide.

[Femoral neck fractures]

Femoral neck fractures (FNF) are the most frequent fractures in the older population and are also of high socioeconomic importance due to the high risk of mortality. The diagnostics are based on the clinical examination and imaging procedures. The classification systems used in the routine clinical practice are oriented towards the prognosis and are therefore a valuable aid in making decisions for the selection of the treatment procedure. Early surgery is decisive for the success of treatment. Older patients (> 60 years) with arthritically damaged hips and a high degree of fracture dislocation benefit from prompt hip replacement (bipolar systems, total hip arthroplasty, dual mobility systems). In contrast, joint-preserving surgery by osteosynthesis is indicated in younger patients with a low degree of dislocation. This article summarizes the clinically relevant aspects of FNF and gives an overview of current treatment strategies with inclusion of the scientific literature.

[Post-traumatic necrosis of the humeral head-Endoprosthesis or joint preservation]

BACKGROUND

Humerus fractures play a major role in daily clinical routine, and subsequent osteonecrosis is common after osteosyntheses.

OBJECTIVES

The current paper highlights the incidence and cause of osteonecrosis after proximal humerus fractures, with respect to presentation of anatomy and risk factors.

METHODS

Display of the literature and therapy options for humerus fracture and subsequent necrosis.

RESULTS

Humerus fractures are the seventh most frequent fractures in humans. The complication rate is 40%, and the described rate of necrosis is up to 34%. Accordingly, the surgical revision rate is at 19% according to recent literature.

CONCLUSION

The treatment of humerus head fracture must consider numerous variables. The individual type of fracture and the current individual situation of the patient must be included in the process of choosing the right treatment. Modern implants with screw locking features should be used, and for certain circumstances the direct implantation of a prosthesis should be considered. Thereby the expectations of the patient with respect to the postoperative activity level play a major role.

Renal expression of Hsp27, 60, and 70 in cases of fatal hypothermia

Macromorphological findings can be missing in cases of fatal hypothermia when the agonal period is very short because of a large difference between environmental and core body temperatures. Expression of heat shock proteins (Hsps) increases under endogenous and exogenous cellular stresses such as thermal stress. These stress proteins can be revealed by immunohistochemical staining. Forty-five cases of death due to hypothermia and a control group of 100 deaths without any antemortem thermal stress were examined for Hsp27, 60, and 70 expression in renal tissue because renal tissue is sensitive to cellular stress. The results revealed no significant difference between Hsp27, 60, and 70 expression in both groups (28.8% positive staining in the study group and 19.0% positive staining in the control group), which is contradictory to a previous study on expression of Hsp70 in renal tissue in cases of fatal hypothermia. Hence, it is currently unclear whether immunohistochemical staining of Hsps supports a morphological diagnosis of fatal hypothermia.

Specialized Mechanosensory Epithelial Cells in Mouse Gut Intrinsic Tactile Sensitivity

BACKGROUND AND AIMS

The gastrointestinal (GI) tract extracts nutrients from ingested meals while protecting the organism from infectious agents frequently present in meals. Consequently, most animals conduct the entire digestive process within the GI tract while keeping the luminal contents entirely outside the body, separated by the tightly sealed GI epithelium. Therefore, like the skin and oral cavity, the GI tract must sense the chemical and physical properties of the its external interface to optimize its function. Specialized sensory enteroendocrine cells (EECs) in GI epithelium interact intimately with luminal contents. A subpopulation of EECs express the mechanically gated ion channel Piezo2 and are developmentally and functionally like the skin's touch sensor- the Merkel cell. We hypothesized that Piezo2+ EECs endow the gut with intrinsic tactile sensitivity.

METHODS

We generated transgenic mouse models with optogenetic activators in EECs and Piezo2 conditional knockouts. We used a range of reference standard and novel techniques from single cells to living animals, including single-cell RNA sequencing and opto-electrophysiology, opto-organ baths with luminal shear forces, and in vivo studies that assayed GI transit while manipulating the physical properties of luminal contents.

RESULTS

Piezo2+ EECs have transcriptomic features of synaptically connected, mechanosensory epithelial cells. EEC activation by optogenetics and forces led to Piezo2-dependent alterations in colonic propagating contractions driven by intrinsic circuitry, with Piezo2+ EECs detecting the small luminal forces and physical properties of the luminal contents to regulate transit times in the small and large bowel.

CONCLUSIONS

The GI tract has intrinsic tactile sensitivity that depends on Piezo2+ EECs and allows it to detect luminal forces and physical properties of luminal contents to modulate physiology.

Characteristics of Medically Transported Critically Ill Children with Respiratory Failure in Latin America: Implications for Outcomes

Several challenges exist for referral and transport of critically ill children in resource-limited regions such as Latin America; however, little is known about factors associated with clinical outcomes. Thus, we aimed to describe the characteristics of critically ill children in Latin America transferred to pediatric intensive care units for acute respiratory failure to identify risk factors for mortality. We analyzed data from 2,692 patients admitted to 28 centers in the Pediatric Collaborative Network of Latin America Acute Respiratory Failure Registry. Among patients referred from another facility (773, 28%), nonurban transports were independently associated with mortality (adjusted odds ratio = 9.4; 95% confidence interval: 2.4–36.3).

Anticancer innovative therapy: Highlights from the ninth annual meeting

The Ninth Annual Conference of "Anticancer Innovative Therapy", organized by Fondazione IRCCS Istituto Nazionale dei Tumori di Milano (Fondazione IRCCS INT) and hosted by Hotel Michelangelo, was held in Milan on 25 January 2019. Cutting-edge science was presented in two main scientific sessions: i) pre-clinical evidences and new targets, and ii) clinical translation. The Keynote lecture entitled "Cancer stem cells (CSCs): metabolic strategies for their identification and eradication" presented by M. Lisanti, was one of the highlights of the conference. One key concept of the meeting was how the continuous advances in our knowledge about molecular mechanisms in various fields of research (cancer metabolism reprogramming, epigenetic regulation, transformation/invasiveness, and immunology, among others) are driving cancer research towards more effective personalized antineoplastic strategies. Specifically, recent preclinical data on the following topics were discussed: 1. Polycomb group proteins in cancer; 2. A d16HER2 splice variant is a flag of HER2 addiction across HER2-positive cancers; 3. Studying chromatin as a nexus between translational and basic research; 4. Metabolomic analysis in cancer patients; 5. CDK4-6 cyclin inhibitors: clinical activity and future perspectives as immunotherapy adjuvant; and 6. Cancer stem cells (CSCs): metabolic strategies for their identification and eradication. In terms of clinical translation, several novel approaches were presented: 1. Developing CAR-T cell therapies: an update of preclinical and clinical development at University of North Carolina; 2. Vγ9Vδ2 T-cell activation and immune suppression in multiple myeloma; 3. Predictive biomarkers for real-world immunotherapy: the cancer immunogram model in the clinical arena; and 4. Mechanisms of resistance to immune checkpoint blockade in solid tumors. Overall, the pre-clinical and clinical findings presented could pave the way to identify novel actionable therapeutic targets to significantly enhance the care of persons with cancer.

Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.

Past climate changes in Greenland ice were accompanied by large aerosol concentration changes. Here, the authors show that by correcting for transport effects, reliable source changes for biogenic aerosol from North America, sea salt aerosol from the North Atlantic, and dust from East Asian deserts can be derived.

Selective increase of cerebrospinal fluid IL-6 during experimental systemic inflammation in humans: association with depressive symptoms

Systemic inflammation is accompanied by profound behavioral and mood changes that resemble symptoms of depression. Findings in animals suggest that pro-inflammatory cytokines released by activated immune cells in the periphery evoke these behavioral symptoms by driving inflammatory changes in the brain. However, experimental data in humans are lacking. Here we demonstrate in healthy male volunteers (10 endotoxin treated, 8 placebo treated) that intravenous administration of low-dose endotoxin (0.8 ng/kg body weight), a prototypical pathogen-associated molecular pattern that activates the innate immune system, not only induces a significant increase in peripheral blood cytokine concentrations (that is, tumor necrosis factor-α, interleukin (IL)-6, IL-10) but also results, with some latency, in a robust and selective increase of IL-6 in the cerebrospinal fluid (CSF). Moreover, we found a strong association between the endotoxin-induced increase of IL-6 in the CSF and the severity of mood impairment, with larger increases in CSF IL-6 concentration followed by a greater deterioration in mood. Taken together, these findings suggest that the appearance of depressive symptoms in inflammatory conditions might be primarily linked to an increase in central IL-6 concentration, identifying IL-6 as a potential therapeutic target in mood disorders.

What Makes You Feel Sick After Inflammation? Predictors of Acute and Persisting Physical Sickness Symptoms Induced by Experimental Endotoxemia

We aimed to identify statistical predictor variables of lipopolysaccharide (LPS)-induced physical sickness symptoms during the acute and late inflammatory phases using multivariate regression analyses. Data from N = 128 healthy volunteers who received i.v. LPS injection (0.4 or 0.8 ng/kg) or placebo were pooled for analyses. Physical sickness symptoms experienced during the acute (0-6h postinjection) and late (6-24h postinjection) phases were assessed with the validated General-Assessment-of-Side-Effects (GASE) questionnaire. LPS-treated subjects reported significantly more physical sickness symptoms. Physical symptoms during the acute phase were associated with LPS-induced mood impairments and interleukin (IL)-6 increases, explaining 28.5% of variance in GASE scores. During late phase, LPS-induced increases in cortisol and IL-6 plasma concentrations and baseline depression were significant predictor variables, explaining 38.5% of variance. In patients with recurrent or chronic inflammatory states, these factors may act as risk factors ultimately contributing to an exacerbation of sickness symptoms, and should be considered as potential targets for therapeutic strategies.

Effects of Neurexan ® in an experimental acute stress setting--An explorative double-blind study in healthy volunteers

AIMS

The objective of this study was to assess the efficacy profile of Nx4 (Neurexan ®) in an acute experimental stress setting. An acute stress reaction is a biopsychological condition arising in response to an event that is individually regarded as emotionally stressful. Medications can mitigate stress perception and stress reactions, but may also have side effects.

MATERIALS AND METHODS

Sixty-four healthy male and female volunteers participated in this prospective two-arm two-site study following an explorative randomized placebo-controlled double-blind study design. Participants took six tablets of either Nx4 or placebo during a time period of 2.5h before exposure to an acute psychological stressor (Trier Social Stress Test), and were subsequently monitored for 1.5h. Subjective stress ratings as well as cardiovascular and neuroendocrine parameters were analyzed before and after stress exposure.

KEY FINDINGS

All changes in primary and secondary efficacy parameters corresponded well with the experimental acute stress setting. Nx4 did not affect subjective stress ratings but significantly diminished stress-induced increases in salivary cortisol and plasma adrenaline. Nx4 was as safe as placebo and very well tolerated.

SIGNIFICANCE

The results suggest an attenuated neuroendocrine stress response in healthy volunteers induced by Nx4. However, further investigations are needed to confirm these observations as well as to better understand why some parameters were affected while others were not. Future investigations should be extended to chronically stressed individuals with a greater disposition to experience stress in everyday life. ClinicalTrials.gov Identifier: NCT01703819.

[No improved survival rate in severely injured patients by prehospital intubation : A retrospective data analysis and matched-pair analysis]

BACKGROUND

Training programs for the treatment of trauma patients generally recommend establishing a secure airway if the patient presents with a Glasgow coma scale (GCS) score of less than 9; however, the evidence for its effectiveness is rather sparse. This study analyzed the effect of preclinical intubation on mortality of patients with a GCS <9 in an emergency medical situation.

METHODS

This retrospective analysis included patients who were primarily admitted to a German level 1 trauma center between 2002 and 2012 with an injury severity score (ISS) ≥ 16, a GCS < 9 and primary transport from the site of the accident. Data were collected from the trauma registry of the German Society for Trauma Surgery and from hospital records. A total of 455 patients were included and a matched-pair analysis of 62 patients was conducted.

RESULTS

Both analytical methods showed no significant reduction in mortality rate after prehospital intubation. In the retrospective analysis intubated patients presented with a significantly lower systolic blood pressure on admission, received a higher amount of fluid volume at all phases of treatment and arrived at the hospital after a prolonged rescue time. In the matched-pair analysis, intubated patients also received a higher amount of fluid volume and showed better peripheral oxygen saturation on admission. No further differences between the groups could be found.

CONCLUSION

It appears that preclinical intubation in trauma patients with a GCS < 9 does not result in a better outcome. The preclinical intubation resulted in a reduced systolic blood pressure on arrival at hospital, a prolonged preclinical rescue time and a greater amount of infused fluid volume.

[Case fatality rate and outcome in multiply injured patients after trauma: influence of specialisation from the first treating physician - an analysis of 198 patients from a national trauma centre]

BACKGROUND

The treatment of multiple injured patients is a highly demanding process concerning the amount and speed of gathered information. Physicians have to evaluate the situation and begin a treatment immediately. There may be influencing variables in the pre-clinical treatment which are correlated to the specialisation of the first treating physician and influencing the outcome of the patient. The aim of this study was to examine the influence of the specialisation of the first treating physician on the pre-clinical treatment and the resulting outcome.

PATIENTS AND METHODS

All trauma patients of our department from 2007 to 2010 who fulfilled the following criteria were included into our study: completely recorded DIVI-emergency protocol with declared specialisation of the first treating physician and inclusion into the trauma register of the DGU. This group of patients was divided into three groups according to the specialisation of the first treating physician (anaesthesia, surgery and other) and compared with one another.

RESULTS

The study group consisted of 198 patients. 76 were treated by anaesthesiologists, 58 by surgeons, and 64 by physicians of other specialisations. The Injury Severity Score (ISS), the age and the distribution between the sexes showed no significant differences. Surgeons applied significantly less volume pre-clinically (794 ml [anesthesiologists: 1275 ml, others: 1231 ml; p value = 0.036]), the haemoglobin value was higher in the surgeon-treated group. This was also reflected in the applied blood transfusions at admission. The pre-clinical intubation rates (anaesthesiologists 48.7 %, others 37.5 %, surgeons 31 % [p value = 0.11]), the ventilator free days within the first 30 days after admission (anaesthesiologists 21.8, others 21.0, surgeons 25.8), intensive care unit free days within the first 30 days after admission (anaesthesiologists 18.4, others 18.5, surgeons 22.4) as well as the rescue time and case fatality rate showed no significant differences between the different groups.

CONCLUSION

Multiply injured patients get a different treatment from the different specialised physicians in the pre-clinical phase. There were differences in the pre-clinical applied volume and haemoglobin value. Rescue time and intubation rate as well as outcome parameters were not statistically different. The case fatality rate in total was not significantly different between the 3 groups.

Diazoxide attenuates autoimmune encephalomyelitis and modulates lymphocyte proliferation and dendritic cell functionality

Activation of mitochondrial ATP-sensitive potassium (KATP) channels is postulated as an effective mechanism to confer cardio and neuroprotection, especially in situations associated to oxidative stress. Pharmacological activation of these channels inhibits glia-mediated neuroinflammation. In this way, diazoxide, an old-known mitochondrial KATP channel opener, has been proposed as an effective and safe treatment for different neurodegenerative diseases, demonstrating efficacy in different animal models, including the experimental autoimmune encephalomyelitis (EAE), an animal model for Multiple Sclerosis. Although neuroprotection and modulation of glial reactivity could alone explain the positive effects of diazoxide administration in EAE mice, little is known of its effects on the immune system and the autoimmune reaction that triggers the EAE pathology. The aim of the present work was to study the effects of diazoxide in autoimmune key processes related with EAE, such as antigen presentation and lymphocyte activation and proliferation. Results show that, although diazoxide treatment inhibited in vitro and ex-vivo lymphocyte proliferation from whole splenocytes it had no effect in isolated CD4(+) T cells. In any case, treatment had no impact in lymphocyte activation. Diazoxide can also slightly decrease CD83, CD80, CD86 and major histocompatibility complex class II expression in cultured dendritic cells, demonstrating a possible role in modulating antigen presentation. Taken together, our results indicate that diazoxide treatment attenuates autoimmune encephalomyelitis pathology without immunosuppressive effect.

Synchronous change of atmospheric CO2 and Antarctic temperature during the last deglacial warming

Understanding the role of atmospheric CO2 during past climate changes requires clear knowledge of how it varies in time relative to temperature. Antarctic ice cores preserve highly resolved records of atmospheric CO2 and Antarctic temperature for the past 800,000 years. Here we propose a revised relative age scale for the concentration of atmospheric CO2 and Antarctic temperature for the last deglacial warming, using data from five Antarctic ice cores. We infer the phasing between CO2 concentration and Antarctic temperature at four times when their trends change abruptly. We find no significant asynchrony between them, indicating that Antarctic temperature did not begin to rise hundreds of years before the concentration of atmospheric CO2, as has been suggested by earlier studies.

Effects of nanopolystyrene on the feeding behavior of the blue mussel (Mytilus edulis L.)

As the industrial production of nanoplastic and the degradation of microplastic into smaller particles at sea increase, the potential amount of nanoplastics in the marine environment rises. It has been reported that mussels uptake 100-nm polystyrene (PS) beads; to date, however, the effects of this uptake on the organism are unknown. In the present study, the authors investigated the effects of 30-nm PS on the feeding behavior of the blue mussel (Mytilus edulis) by exposing the organism to different nano PS and different algae (Pavlova lutheri) concentrations. The state of nano PS aggregation in the exposure medium was assessed using dynamic light scattering. In all treatments that contained nano PS, M. edulis produced pseudofeces. The total weight of the feces and pseudofeces increased with increasing nano PS and increasing algae concentration. Furthermore, M. edulis reduced its filtering activity when nano PS was present but still caused a decrease in the apparent nano PS concentration in the water. The presence of nano PS around the foot of M. edulis after the bioassay confirmed that the organism removed nano PS from the water. Chronic effect studies are therefore needed to investigate the effects of nanoplastics in M. edulis and possible consequences for its predators, including humans.

[Multisegmental and minimally invasive dorsal stabilization of thoracic and lumbar vertebral column. Operative technique]

Dorsal stabilization of the thoracic and lumbar vertebral column is still the fundamental technique for acute treatment of unstable vertebral fractures and intervertebral ligament injuries as well as in tumor surgery and the treatment of degenerative and inflammatory diseases. The aim is to achieve the best possible anatomical and axis-correct stabilization of the physical lordosis and kyphosis. This article describes in detail the operational preparation (e.g. necessary imaging, possible positioning of the patient) and procedure (e.g. access, placement of screws and plates, wound closure and postoperative follow-up treatment) and possible complications due to misplaced pedicle screws, the rate of which can possibly be reduced by intraoperative 3D imaging.

[Preoperative planning and reconstruction in primary total hip arthroplasty with and without modular necks]

STUDY AIM

Preoperative planning is regarded as an important requirement for successful implantation of a hip replacement. One of the crucial aspects of planning is the restoration of the normal anatomy of the hip as this increases the chances for good clinical function and reduces wear debris. Various systems for restoration of the hip are available including stem systems with different stem sizes and offsets and so-called modular stem systems which have the additional possibility of adjusting the neck length and angle. The aim of this study was to investigate to what extent a good postoperative outcome can be achieved using a modular and a non-modular stem system in comparison with preoperative planning. Furthermore, the study assessed the difference between preoperative planning carried out by a senior surgeon and by an assistant surgeon.

METHOD

Standard preoperative and postoperative digitalised radiographs with an anteroposterior view of the pelvis centred over the pubic symphysis were made. Preoperative planning aimed for exact reconstruction of offset and equal leg length. Preoperative planning and evaluation of the postoperative outcome were performed by digitalised image-analysing software. The symptom-free contralateral hip served as reference for anatomic reconstruction.

RESULTS

The postoperative results confirmed the preoperative planning. The preoperative planning was successfully implemented with both systems. Postoperatively, we observed a slightly reduced offset (Group 1: 3.6 mm, Group 2: 3.54 mm) and an increase in leg length of less than 5 mm in both groups. There was no significant difference between the preoperative planning carried out by the senior surgeon and the assistant surgeon.

CONCLUSION

Implementation of preoperative planning with both the modular and the non-modular system was very satisfactory. It was irrelevant if the planning was carried out by a senior surgeon or by an assistant surgeon in the first year of training.

[Modification of the Blackburne-Peel ratio for improved application in total knee arthroplasty]

BACKGROUND

The methods currently used to measure patella height in relation to the tibiofemoral joint line after total knee arthroplasty are not easily reproducible. For this reason we modified the Blackburne-Peel ratio.

MATERIALS AND METHODS

Instead of taking the tibial joint line as the reference line, we constructed a tangent on the femoral condyle. In addition, we took the greatest diameter of the patella from the tip of the patella as a measuring line.

RESULTS

Compared with the classic Blackburne-Peel and Caton-Deschamps ratios, it was much easier to determine the patella height in osteoarthritic knees and after total knee replacement using this modified Blackburne-Peel ratio. Factors such as the height of the polyethylene inlay, the slope of the tibial component, and superimposition of the patellar joint line can be disregarded. Preoperative and postoperative reference lines can be compared readily. Furthermore, the classic Blackburne-Peel ratio shows a greater tendency to interpret the measurements after total knee arthroplasty as pseudo-patella baja. The interobserver variability was good for all ratios.

CONCLUSION

We can therefore recommend the modified Blackburne-Peel ratio for measuring patella height in relation to the tibiofemoral joint line after total knee arthroplasty.

[Accuracy of rotational positioning of the femoral component using the tibial-cut-first technique]

AIM

Problems with the patellofemoral joint are still one of the most common difficulties after total knee arthroplasty. One of the main reasons for these problems seems to be the rotatory malposition of the femoral component. We examined the rotation of the femoral component and the symmetry of the flexion gap of knee prostheses implanted using the tibial-cut-first technique.

METHOD

The radiographs of 58 consecutive patients who underwent primary LCS total knee arthroplasty in 2008 were examined retrospectively. The rotation of the femoral component was determined intraoperatively using the femoral positioner and depended on the amount of tibial resection and the tension of the collateral ligaments. The position was then checked by means of three anatomic landmarks: the epicondylar axis, the posterior condyles and the Whiteside line. We used Kanekasu's technique for the radiographs. With this technique it was possible to ascertain the rotation of the femoral component after total knee arthroplasty easily and with a low level of radiation. It was also possible to determine the opening of the flexion gap.

RESULTS

The radiographs showed a slight external rotation of the femoral component of 1.31°. The opening of the flexion gap was increased laterally, but only by 1.5°.

CONCLUSION

In this study, determination of femoral rotation using the tibial-cut-first technique resulted in a slight external rotation of the femoral component. Furthermore, it is possible to create an almost symmetrical flexion gap with this method.

P2 receptor expression in the dopaminergic system of the rat brain during development

Extracellular ATP facilitates the release of dopamine via P2 receptor activation in parts of the mesolimbic system. To characterize P2X/Y receptor subtypes in the developing dopaminergic system, their expression in organotypic slice co-cultures including the ventral tegmental area/substantia nigra (VTA/SN) complex and the prefrontal cortex (PFC) was studied in comparison to the receptor expression in 3-5 day-old and adult rats. Reverse transcriptase-polymerase chain reaction (RT-PCR) with specific primers for the P2X(1,2,3,4,6,7) and P2Y(1) receptors in the tissue extracts of organotypic co-cultures revealed the presence of the P2X and P2Y receptor mRNAs investigated. Multiple immunofluorescence labeling of the P2X/Y receptor protein indicated differences in the regional expression in the organotypic co-cultures after 10 days of cultivation (VTA/SN, P2X(1,2,3,4,6,7), P2Y(1,6,12); PFC, P2X(1,3,4,6,7), P2Y(1,2,4,6,12)). At postnatal days 3-5, an immunofluorescence mostly comparable to that of adult rats was observed (VTA/SN and PFC: P2X(1,2,3,4,6,7), P2Y(1,2,4,6,12)). There was one important exception: the P2X(7) receptor immunocytochemistry was not found in adult tissue, suggesting a potential role of this receptor in the development. Only few P2 receptors (e.g. P2X(1), P2Y(1)) were expressed at fibers interconnecting the dopaminergic VTA/SN with the PFC in the organotypic co-cultures. The treatment of the cultures with the ATP analogues 2-methylthio-ATP and alpha,beta-methylene-ATP induced an increase in axonal outgrowth and fiber density, which could be inhibited by pre-treatment with the P2X/Y receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid. The co-localization of the dopamine-(D1) receptor with the P2X(1) receptor in organotypic slice cultures was evident. In the PFC of the co-cultures, and that of young but not adult rats, a number of tyrosine hydroxylase (TH)-positive cells also possessed P2Y(1)-immunoreactivity (IR). Additionally, a strong P2Y(1)-IR was observed on astrocytes. The present results show a time-, region- and cell type-dependent in vitro and in vivo expression pattern of different P2 receptor subtypes in the dopaminergic system indicating the involvement of ATP and its receptors in neuronal development and growth.

Interleukin-6, procalcitonin and TNF-alpha: markers of peri-prosthetic infection following total joint replacement

This prospective study evaluates the role of new laboratory markers in the diagnosis of deep implant infection in 78 patients (41 men and 37 women) with a revision total knee or hip replacement. The mean age at the time of operation was 64.0 years (19 to 90). Intra-operative cultures showed that 21 patients had a septic and 57 an aseptic total joint replacement. The white blood cell count, the erythrocyte sedimentation rate and levels of C-reactive protein, interleukin-6, procalcitonin and tumour necrosis factor (TNF)-alpha were measured in blood samples before operation. The diagnostic cut-off values were determined by Received Operating Characteristic curve analysis. C-reactive protein (> 3.2 md/dl) and interleukin-6 (> 12 pg/ml) have the highest sensitivity (0.95). Interleukin-6 is less specific than C-reactive protein (0.87 vs 0.96). Combining C-reactive protein and interleukin-6 identifies all patients with deep infection of the implant. Procalcitonin (> 0.3 ng/ml) and TNF-alpha (> 40 ng/ml) are very specific (0.98 vs 0.94) but have a low sensitivity (0.33 vs 0.43). The combination of C-reactive protein and interleukin-6 measurement provide excellent screening tests for infection of a deep implant. A highly specific marker such as procalcitonin and pre-operative aspiration of the joint might be useful in identifying patients with true positive C-reactive protein and/or interleukin-6 levels.

P2 receptor-stimulation influences axonal outgrowth in the developing hippocampus in vitro

Extracellular ATP might act as a trophic factor on growing axons during development of the CNS via P2 receptors. In the present study the postnatal presence of selected P2 receptor subtypes was analyzed and their putative trophic capacity in entorhino-hippocampal slice co-cultures of mouse brain was tested. The effect of the P2 receptor ligands 2-methylthioadenosine-5'-triphosphate (P2X/Y receptor agonist) and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (P2X/Y receptor antagonist) on axonal growth and fiber density of biocytin-labeled hippocampal projections was compared both with untreated cultures and with cultures treated with artificial cerebrospinal fluid. After 10 days in vitro, double immunofluorescence labeling revealed the expression of P2X(1), P2X(2), P2X(4) as well as P2Y(1) and P2Y(2) receptors in the examined regions of entorhinal fiber termination. Further, quantitative analysis of identified biocytin-traced entorhinal fibers showed a significant increase in fiber density in the dentate gyrus after incubation of the slices with the P2 receptor agonist 2-methylthioadenosine-5'-triphosphate. This neurite outgrowth promoting effect was completely abolished by the P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid. Our in vitro data indicate that ATP via its P2X and P2Y receptors can shape hippocampal connectivity during development.

The di-aromatic pentapeptide repeats of the human peroxisome import receptor PEX5 are separate high affinity binding sites for the peroxisomal membrane protein PEX14

PEX5 functions as a mobile import receptor for peroxisomal matrix proteins with a peroxisomal targeting signal 1 (PTS1). A critical step within the PTS1-import pathway is the interaction between PEX5 and the peroxisome membrane-associated protein PEX14. Based on two-hybrid analyses in mammalian cells and complementary in vitro binding assays, we demonstrate that the evolutionarily conserved pentapeptide repeat motifs, WX(E/D/Q/A/S)(E/D/Q)(F/Y), in PEX5 bind to PEX14 with high affinity. The results obtained indicate that each of the seven di-aromatic pentapeptides of human PEX5 interacts separately at the same binding site in the N terminus of PEX14 with equilibrium dissociation constants in the low nanomolar range. Mutational analysis of the PEX14-binding motifs reveals that the conserved aromatic amino acids at position 1 or 5 are essential for high affinity binding. We propose that the side chains of the aromatic amino acids are in close proximity as part of an amphipathic alpha-helix and together form hydrophobic anchors for binding PEX5 to individual PEX14 molecules.

Gelsolin as a calcium-regulated actin filament-capping protein

Various concentrations of gelsolin (25-100 nM) were added to 2 microM polymerized actin. The concentrations of free calcium were adjusted to 0.05-1.5 microM by EGTA/Ca2+ buffer. Following addition of gelsolin actin depolymerization was observed that was caused by dissociation of actin subunits from the pointed ends of treadmilling actin filaments and inhibition by gelsolin of polymerization at barbed ends. The time course of depolymerization revealed an initial lag phase that was followed by slow decrease of the concentration of polymeric actin to reach the final steady state polymer and monomer concentration. The initial lag phase was pronounced at low free calcium and low gelsolin concentrations. On the basis of quantitative analysis the kinetics of depolymerization could be interpreted as capping, i.e. binding of gelsolin to the barbed ends of actin filaments and subsequent inhibition of polymerization, rather than severing. The main argument for this conclusion was that even gelsolin concentrations (100 nM) that exceed the concentration of filament ends ( approximately 2 nM), cause the filaments to depolymerize at a rate that is similar to the rate of depolymerization of the concentration of pointed ends existing before addition of gelsolin. The rate of capping is directly proportional to the free calcium concentration. These experiments demonstrate that at micromolar and submicromolar free calcium concentrations gelsolin acts as a calcium-regulated capping protein but not as an actin filament severing protein, and that the calcium binding sites of gelsolin which regulate the various functions of gelsolin (capping, severing and monomer binding), differ in their calcium affinity.

Tetrachloro- and tetrabromoarsonium(V) cations: raman and 75As, 19F NMR spectroscopic characterization and X-ray crystal structures of [AsCl4][As(OTeF5)6] and [AsBr4][AsF(OTeF5)5]

The salts [AsX4][As(OTeF5)6] and [AsBr4][AsF(OTeF5)5] (X = Cl, Br) have been prepared by oxidation of AsX3 with XOTeF5 in the presence of the OTeF5 acceptors As(OTeF5)5 and AsF(OTeF5)4. The mixed salts [AsCl4][Sb(OTeF5)6-nCl(n-2)] and [AsCl4][Sb(OTeF5)6-nCl(n)] (n > or = 2) have also been prepared. The AsBr4+ cation has been fully structurally characterized for the first time in SO2ClF solution by 75As NMR spectroscopy and in the solid state by a single-crystal X-ray diffraction study of [AsBr4][AsF(OTeFs)5]: P1, a = 9.778(4) A, b = 17.731(7) A, c = 18.870(8) A, alpha = 103.53(4)degrees, beta = 103.53(4) degrees, gamma = 105.10(4) degrees, V = 2915(2) A3, Z = 4, and R1 = 0.0368 at -183 degrees C. The crystal structure determination and solution 75As NMR study of the related [AsCl4][As(OTeF5)6] salt have also been carried out: [AsCl4][As(OTeF5)6], R3, a = 9.8741(14) A, c = 55.301(11) A, V= 4669(1) A3, Z = 6, and R1 = 0.0438 at -123 degrees C; and R3, a = 19.688(3) A, c = 55.264(11) A, V= 18552(5) A3, Z = 24, and R1 = 0.1341 at -183 degrees C. The crystal structure of the As(OTeF5)6- salt reveals weaker interactions between the anion and cation than in the previously known AsF6- salt. The AsF(OTeF5)5- anion is reported for the first time and is also weakly coordinating with respect to the AsBr4+ cation. Both cations are undistorted tetrahedra with bond lengths of 2.041(5)-2.056(3) A for AsCl4+ and 2.225(2)-2.236(2) A for AsBr4+. The Raman spectra are consistent with undistorted AsX4+ tetrahedra and have been assigned under Td point symmetry. The 35Cl/37Cl isotope shifts have been observed and assigned for AsCl4+, and the geometrical parameters and vibrational frequencies of all known and presently unknown PnX4+ (Pn = P, As, Sb, Bi; X = F, Cl, Br, I) cations have been calculated using density functional theory methods.

Derivation of insertin

Insertin is an actin-binding protein that has been isolated from chicken gizzard smooth muscle that has been shown to be highly homologous to amino acids 962-1292 of tensin [Weigt et al., 1992]. Because of the high homology, we investigated the question whether the mRNAs of insertin and of tensin are derived from the same gene by alternative splicing, whether insertin and tensin are encoded by two different genes, or whether insertin is a proteolytic fragment of tensin. In a Northern blot analysis, mRNA from chicken gizzard was hybridized with oligonucleotides specific for tensin and for the insertin domain of tensin. The tensin-specific oligonucleotide hybridized only with the previously reported 8- and 10-kbp RNAs. However, the insertin domain-specific oligonucleotide hybridized with a 1.2 and a 1.6 kbp RNA in addition to the 8 and 10 kbp RNA. The 1.2- and 1.6-kbp RNA occurred in small amounts, as compared with the 8- and 10-kbp RNA. Southern blot analysis of DNA cleaved by the restriction endonucleases BamH1 and HindIII demonstrated that only one gene for the insertin and tensin exists. Insertin isolated from chicken gizzard smooth muscle was investigated by mass spectrometry. The N-termini of three isolated peptides were found to begin at adjacent amino acids and were likely to be formed from tensin by proteolysis. The results suggest that, for insertin, an mRNA exists that is derived from one gene common for insertin and tensin. However, the insertin-specific mRNA contributes relatively little to expression of insertin domains in cells. Insertin preparations from chicken gizzard contain mainly insertin domains formed from tensin by proteolysis.

Assessment of the adhesion quality of fusion-welded silicon wafers with nonlinear ultrasound

Diffusion bonded silicon wafers are employed in the semiconductor industry. Their bonding quality must be monitored by a nondestructive testing technique. We present an ultrasonic technique allowing us to monitor the quality of the diffusion bond by measuring the anharmonic content of a transmitted ultrasonic wave. The anharmonicity is caused by weak bonds and manifests itself at high dynamic strains exerted by the ultrasonic wave. The source of nonlinearity is located in the rim of delaminations in the interface.

Co-operative binding of Ca2+ ions to the regulatory binding sites of gelsolin

The rate of association of actin with gelsolin was measured at various Ca2+ and ATP concentrations. The fraction of Ca2+-activated gelsolin was determined by quantitative evaluation of the association rates thereby assuming that Ca2+-binding gelsolin associates with actin and Ca2+-free gelsolin does not. A plot of the fraction of Ca2+-activated gelsolin vs. the free Ca2+ concentration revealed a sigmoidal shape suggesting that co-operative binding of Ca2+ ions is required for activation of gelsolin. A good fit of the experimental data by calculated binding curves was obtained if two Ca2+ ions were assumed to bind to actin in a highly co-operative manner. ATP decreased the rate of association of gelsolin with actin and bound to gelsolin at a low affinity (Kd = 32 microm for Ca2+-free and Kd = 400 microm for Ca2+-activated gelsolin). In contrast, a 1 : 1 gelsolin-actin complex was found to be activated for association with actin by a single Ca2+ ion in a non-co-operative manner.

Kinetic evidence for a readily exchangeable nucleotide at the terminal subunit of the barbed ends of actin filaments

The time course of actin depolymerization was quantitatively analyzed to obtain insight into the reactions occurring during actin disassembly. Polymeric actin was diluted, and subsequently the time course of depolymerization was measured. In the presence of 0.5 mM ATP, 100 mM KCl, and 1 mM MgCl2, continuous depolymerization was observed both when the filaments were carefully diluted and when the filaments were fragmented to produce short filaments. The rates of the reactions that are known to occur during depolymerization, such as dissociation and association of ADP- and ATP-actin molecules and exchange of nucleotides bound to monomeric actin, were determined by independent experiments. When the determined rate parameters were used to calculate the time course of depolymerization, consistently in the simulations fast depolymerization of ADP-actin was followed by slower polymerization of ATP-actin that was formed from ADP-actin by nucleotide exchange. The lack of fast depolymerization and subsequent slower polymerization in the experiments suggests that our present conception about actin disassembly requires modification. Good agreement of calculated time courses with the experimentally determined continuous depolymerization was achieved if ADP bound to the terminal subunit of barbed filament ends was assumed to be readily exchangeable for ATP. Fast nucleotide exchange at terminal subunits may contribute to the stability of barbed filament ends and to their role as polymerizing ends in living cells.

[Teleconsultation network for ophthalmology--experiences and results]

MOTIVATION

Telemedical services for ophthalmology are developed within the OPHTEL project, which has been funded by the European Union and by the Bavarian government in the Bavaria-online initiative.

METHODS

Seven private ophthalmologists, one university eye clinic, one clinical Diabetes center and an informatics research institute are connected within a teleconsultation network. Asynchronous (based on Internet E-Mail) and synchronous (based on ISDN-mediated videoconferencing tools) types of teleconsultations are realized.

RESULTS

86 teleconsultations (62 asynchronous, 23 synchronous) took place within the first 10 months. Complex and rare eye diseases as well as interdisciplinary questions (ophthalmology--diabetology) are the main area of medical communication interest. Legal and security problems are discussed.

CONCLUSIONS

Telemedical services must be understood as a complete process of medical care on the basis of modern communication technologies, which influences also the management of this process.

The rate of annealing of actin tropomyosin filaments depends strongly on the length of the filaments

Actin tropomyosin filaments were sheared to produce short filaments. Following incubation for 0 to 10000 s annealing of the filaments was assayed by determination of the rate of polymerization of monomeric actin onto the filament ends. The rate of decrease of the concentration of filament ends was found to be proportional to its fourth power. In contrast, the rate of end-to-end association of actin filaments in the absence of tropomyosin was proportional to the square of the concentration of filament ends. The strong dependence on the filament length of the rate of annealing of actin tropomyosin filaments was interpreted by the model of Hill (Biophys. J., 44, 285-288 (1983)) who pointed out that the rate constant of end-to-end association of long rod-like filaments is expected to depend on the length of the filaments for sterical conditions.

The end of a polymerizing actin filament contains numerous ATP-subunit segments that are disconnected by ADP-subunits resulting from ATP hydrolysis

ATP hydrolysis by copolymers of ATP-actin and ADP-actin was investigated in order to analyze the effect of interfaces between ATP-subunits and ADP-subunits on hydrolysis of actin-bound ATP. Copolymers of ATP- and ADP-subunits were formed by polymerization of ATP- and ADP-actin monomers onto filaments. By changing the ratio of polymerizing ATP-actin monomers to ADP-actin monomers, the number of interfaces between ATP- and ADP-subunits and of ATP-subunits only surrounded by further ATP-subunits was varied. The rate of actin polymerization and of ATP hydrolysis was measured simultaneously on the same samples. The lag time between incorporation of actin monomers into filaments and subsequent ATP hydrolysis was found to be similar both for polymerized ATP-actin and for copolymers formed by various ratios of ATP- to ADP-actin. The experiments were performed in the presence of 1 mM MgCl2, 0.05 mM CaCl2, and 100 mM KCl or of 1 mM MgCl2, and 0.4 mM EGTA. The type of cations was found to have no major effect on the rate of ATP hydrolysis. A quantitative evaluation of the experimental data suggests that ATP at interfaces between ATP- and ADP-subunits is hydrolyzed not more than 10 times faster than ATP of subunits surrounded by further ATP-subunits. On the basis of these results, one can conclude that an actin filament onto which ATP-actin monoMers polymerize contains numerous segments of ATP-subunits that are disconnected by ADP-subunits resulting from ATP hydrolysis. The average length of the numerous ATP segments of a steadily polymerizing filament is in the range of 10 ATP-subunits or below.