Plasma and Cerebrospinal Fluid Population Pharmacokinetics of Vancomycin in Patients with External Ventricular Drain

Vancomycin is a commonly used antibacterial agent in patients with primary central nervous system (CNS) infection. This study aims to examine predictors of vancomycin penetration into cerebrospinal fluid (CSF) in patients with external ventricular drainage and the feasibility of CSF sampling from the distal drainage port for therapeutic drug monitoring. Fourteen adult patients (9 with primary CNS infection) were treated with vancomycin intravenously. The vancomycin concentrations in blood and CSF (from proximal [CSF_P] and distal [CSF_D] drainage ports) were evaluated by population pharmacokinetics. Model-based simulations were conducted to compare various infusion modes. A three-compartment model with first-order elimination best described the vancomycin data. Estimated parameters included clearance (CL, 4.53 L/h), central compartment volume (Vc, 24.0 L), apparent CSF compartment volume (VCSF, 0.445 L), and clearance between central and CSF compartments (QCSF, 0.00322 L/h and 0.00135 L/h for patients with and without primary CNS infection, respectively). Creatinine clearance was a significant covariate on vancomycin CL. CSF protein was the primary covariate to explain the variability of QCSF. There was no detectable difference between the data for sampling from the proximal and the distal port. Intermittent infusion and continuous infusion with a loading dose reached the CSF target concentration faster than continuous infusion only. All infusion schedules reached similar CSF trough concentrations. Beyond adjusting doses according to renal function, starting treatment with a loading dose in patients with primary CSF infection is recommended. Occasionally, very high and possibly toxic doses would be required to achieve adequate CSF concentrations, which calls for more investigation of direct intraventricular administration of vancomycin. (This study has been registered at ClinicalTrials.gov under registration no. NCT04426383).

Large diameter hemicraniectomy does not improve long-term outcome in malignant infarction

INTRODUCTION

In malignant cerebral infarction decompressive hemicraniectomy has demonstrated beneficial effects, but the optimum size of hemicraniectomy is still a matter of debate. Some surgeons prefer a large-sized hemicraniectomy with a diameter of more than 14 cm (HC > 14). We investigated whether this approach is associated with reduced mortality and an improved long-term functional outcome compared to a standard hemicraniectomy with a diameter of less than 14 cm (HC ≤ 14).

METHODS

Patients from the DESTINY (DEcompressive Surgery for the Treatment of malignant INfarction of the middle cerebral arterY) registry who received hemicraniectomy were dichotomized according to the hemicraniectomy diameter (HC ≤ 14 cm vs. HC > 14 cm). The primary outcome was modified Rankin scale (mRS) score ≤ 4 after 12 months. Secondary outcomes were in-hospital mortality, mRS ≤ 3 and mortality after 12 months, and the rate of hemicraniectomy-related complications. The diameter of the hemicraniectomy was examined as an independent predictor of functional outcome in multivariable analyses.

RESULTS

Among 130 patients (32.3% female, mean (SD) age 55 (11) years), the mean hemicraniectomy diameter was 13.6 cm. 42 patients (32.3%) had HC > 14. There were no significant differences in the primary outcome and mortality by size of hemicraniectomy. Rate of complications did not differ (HC ≤ 14 27.6% vs. HC > 14 36.6%, p = 0.302). Age and infarct volume but not hemicraniectomy diameter were associated with outcome in multivariable analyses.

CONCLUSION

In this post-hoc analysis, large hemicraniectomy was not associated with an improved outcome or lower mortality in unselected patients with malignant middle cerebral artery infarction. Randomized trials should further examine whether individual patients could benefit from a large-sized hemicraniectomy.

CLINICAL TRIAL REGISTRATION INFORMATION

German Clinical Trials Register (URL: https://www.drks.de ; Unique Identifier: DRKS00000624).

Posterior reversible encephalopathy syndrome after lung transplantation: Risk factors and management

INTRODUCTION

Posterior reversible encephalopathy syndrome is a rare neurologic complication that can occur under immunosuppressive therapy with CNI after organ transplantation.

METHODS

We retrospectively reviewed medical records of 545 patients who underwent lung transplantation between 2012 and 2019. Within this group, we identified 30 patients with neurological symptoms typical of PRES and compared the characteristics of patients who were diagnosed with PRES (n = 11) to those who were not (n = 19).

RESULTS

The incidence of PRES after lung transplantation was 2%. Notably, 73% of the patients with PRES were female and the mean age was 39.2. Seizure (82% vs. 21%, p = .002) was the most common neurological presentation. The risk of developing PRES was significantly associated with age (OR = .92, p < .0001) and having cystic fibrosis (CF) (OP = 10.1, p < .0001). Creatinine level (1.9 vs. 1.1 mg/dl, p = .047) and tacrolimus trough level (19.4 vs. 16.5 ng/ml, p = .048) within 1 week prior to neurological symptoms were significantly higher in patients with PRES.

CONCLUSION

Renal insufficiency and high tacrolimus levels are associated with PRES. A change of immunosuppressive drug should be done after confirmed PRES diagnosis or immediately in case of severe neurological dysfunction to improve neurological outcomes and minimize the risk of early allograft rejection.

Case Report: Minimal Neurological Deficit of Two Adult Patients With Weston-Hurst Syndrome Due to Early Craniectomy: Case Series and Review of Literature on Craniectomy

Objectives: We describe two new cases of acute hemorrhagic leucoencephalitis (AHLE), who survived with minimal sequelae due to early measures against increased intracranial pressure, particularly craniotomy. The recently published literature review on treatment and outcome of AHLE was further examined for the effect of craniotomy.

Methods: We present two cases from our institution. The outcome of 44 cases from the literature was defined either as good (no deficit, minimal deficit/no daily help) or poor outcome (severe deficit/disabled, death). Patients with purely infratentorial lesions (n = 9) were excluded. Fisher's exact test was applied.

Results: Two cases are presented: A 43-year-old woman with rapidly progressive aphasia and right hemiparesis due to a huge left frontal white matter lesion with rim contrast enhancement. Pathology was consistent with AHLE. The second case was a 56-year-old woman with rapidly progressive aphasia and right hemiparesis. Cranial MRI showed a huge left temporo-occipital white matter lesion with typical morphology for AHLE. Both patients received craniotomy within the first 24 h and consequent immunosuppressive-immunomodulatory treatment and survived with minimal deficits. Out of 35 supratentorial reported AHLE cases, seven patients received decompressive craniotomy. Comparing all supratentorial cases, patients who received craniotomy were more likely to have a good outcome (71 vs. 29%).

Conclusion: Due to early control of the intracranial pressure, particularly due to early craniotomy; diagnosis per biopsy; and immediate start of immunosuppressive-immunomodulatory therapies (cortisone pulse, plasma exchanges), both patients survived with minimal sequelae. Craniotomy plays an important role and should be considered early on in patients with probable AHLE.

Comprehensive flow cytometric reference intervals of leukocyte subsets from six study centers across Europe

A group of European FOCIS Centers of Excellence adapted panels of the Human Immunophenotyping Consortium (HIPC) for whole blood analysis. Using four core panels [T/regulatory T cell/B/natural killer (T/T_reg/B/NK) and myeloid cells] the main leukocyte populations were analyzed in a clinical–diagnostic setting in a harmonized manner across different platforms. As a first step, the consortium presents here the absolute and relative frequencies of the leukocyte subpopulations in the peripheral blood of more than 300 healthy volunteers across six different European centers.

Circulating β cell-specific CD8+ T cells restricted by high-risk HLA class I molecules show antigen experience in children with and at risk of type 1 diabetes

In type 1 diabetes (T1D), autoreactive cytotoxic CD8+ T cells are implicated in the destruction of insulin-producing β cells. The HLA-B*3906 and HLA-A*2402 class I genes confer increased risk and promote early disease onset, suggesting that CD8+ T cells that recognize peptides presented by these class I molecules on pancreatic β cells play a pivotal role in the autoimmune response. We examined the frequency and phenotype of circulating preproinsulin (PPI)-specific and insulin B (InsB)-specific CD8+ T cells in HLA-B*3906+ children newly diagnosed with T1D and in high-risk HLA-A*2402+ children before the appearance of disease-specific autoantibodies and before diagnosis of T1D. Antigen-specific CD8+ T cells were detected using human leucocyte antigen (HLA) class I tetramers and flow cytometry was used to assess memory status. In HLA-B*3906+ children with T1D, we observed an increase in PPI5-12 -specific transitional memory CD8+ T cells compared to non-diabetic, age- and HLA-matched subjects. Furthermore, PPI5-12 -specific CD8+ T cells in HLA-B*3906+ children with T1D showed a significantly more antigen-experienced phenotype compared to polyclonal CD8+ T cells. In longitudinal samples from high-risk HLA-A*2402+ children, the percentage of terminal effector cells within the InsB15-24 -specific CD8+ T cells was increased before diagnosis relative to samples taken before the appearance of autoantibodies. This is the first study, to our knowledge, to report HLA-B*3906-restricted autoreactive CD8+ T cells in T1D. Collectively, our results provide evidence that β cell-reactive CD8+ T cells restricted by disease-associated HLA class I molecules display an antigen-experienced phenotype and acquire enhanced effector function during the period leading to clinical diagnosis, implicating these cells in driving disease.

Patient-reported outcomes in Friedreich's ataxia after withdrawal from idebenone

OBJECTIVES

Friedreich's ataxia is the most common inherited ataxia, and pathogenesis is known to involve mitochondrial oxidative stress. Idebenone is a potent antioxidant which has already been evaluated in several clinical trials in FRDA, with reports of symptomatic benefit but inconclusive objective results. Following patient consultation on design, we have completed a treatment-withdrawal study to establish whether patients could correctly determine their treatment allocation to placebo or idebenone. Our aim was to capture subjective experiences of symptoms such as fatigue, which can be difficult to measure with questionnaires or semi-quantitative scales, particularly in chronic, slowly progressive conditions.

MATERIALS AND METHODS

Patients taking idebenone for at least 12 months as part of the open-label MICONOS Extension Study were randomized to receive either placebo or idebenone continuation for 2-month treatment cycles. The primary endpoint was patient assessment of treatment assignment.

RESULTS

A total of 29 patients were randomized, forming the idebenone group (n = 16) and the placebo group (n = 13). No significant differences were detected between the idebenone and placebo groups on assessment of treatment assignment or early study withdrawal. A small but significant difference in ataxia rating scale scores was detected between treatment groups when considering ambulatory patients only.

CONCLUSIONS

This study provides no data to suggest that FRDA patients could correctly determine their treatment assignment over a 2-month period. We hope that this study design will help inform future trials so that patients' experiences of symptoms are more reliably measured.

Consciousness Indexing and Outcome Prediction with Resting-State EEG in Severe Disorders of Consciousness

We applied the following methods to resting-state EEG data from patients with disorders of consciousness (DOC) for consciousness indexing and outcome prediction: microstates, entropy (i.e. approximate, permutation), power in alpha and delta frequency bands, and connectivity (i.e. weighted symbolic mutual information, symbolic transfer entropy, complex network analysis). Patients with unresponsive wakefulness syndrome (UWS) and patients in a minimally conscious state (MCS) were classified into these two categories by fitting and testing a generalised linear model. We aimed subsequently to develop an automated system for outcome prediction in severe DOC by selecting an optimal subset of features using sequential floating forward selection (SFFS). The two outcome categories were defined as UWS or dead, and MCS or emerged from MCS. Percentage of time spent in microstate D in the alpha frequency band performed best at distinguishing MCS from UWS patients. The average clustering coefficient obtained from thresholding beta coherence performed best at predicting outcome. The optimal subset of features selected with SFFS consisted of the frequency of microstate A in the 2-20 Hz frequency band, path length obtained from thresholding alpha coherence, and average path length obtained from thresholding alpha coherence. Combining these features seemed to afford high prediction power. Python and MATLAB toolboxes for the above calculations are freely available under the GNU public license for non-commercial use ( https://qeeg.wordpress.com ).

Severe disorders of consciousness after acquired brain injury: A single-centre long-term follow-up study

OBJECTIVES

To assess long-term clinical outcome, functional independence and health-related quality of life (HRQOL) in acquired brain injury (ABI) patients with a disorder of consciousness at admission to inpatient rehabilitation.

METHODS

We selected patients from a cohort of ABI patients from a single centre. In addition to mortality, we measured level of consciousness with the Coma Remission Scale, functional independence with the Barthel Index, as well as generic and condition-specific HRQOL with the EQ5D and the "Quality of Life after Brain Injury" (QOLIBRI) respectively.

RESULTS

Half of the obtained sample had died by follow-up. Survivors were younger at onset, in a minimally conscious state (MCS) at admission and had spent longer time in rehabilitation. Patients in a MCS were more likely to survive, and be in a state better than MCS over the follow-up time than patients with an unresponsive wakefulness syndrome (UWS). A small proportion of patients with UWS at admission emerged from MCS at follow-up. Emergence from MCS was associated with traumatic brain injury (TBI) and higher functional independence.

CONCLUSION

Clinical outcome is mostly concordant with previous findings. Survivors' rehabilitation duration suggest revision of current standards. HRQOL results indicate a correlation with functional independence and that condition-specific HRQOL should not be neglected.

Resonance signatures in the body-frame valence photoionization of CF4

Photoionization of the 4t₂ orbital of CF₄ shows overlapping resonances close to threshold, leading to a striking inversion of the photoelectron angular distribution when viewed in the body-frame.

High probability of comorbidities in bronchial asthma in Germany

Clinical experience has shown that allergic and non-allergic respiratory, metabolic, mental, and cardiovascular disorders sometimes coexist with bronchial asthma. However, no study has been carried out that calculates the chance of manifestation of these disorders with bronchial asthma in Saarland and Rhineland-Palatinate, Germany. Using ICD10 diagnoses from health care institutions, the present study systematically analyzed the co-prevalence and odds ratios of comorbidities in the asthma population in Germany. The odds ratios were adjusted for age and sex for all comorbidities for patients with asthma vs. without asthma. Bronchial asthma was strongly associated with allergic and with a lesser extent to non-allergic comorbidities: OR 7.02 (95%CI:6.83-7.22) for allergic rhinitis; OR 4.98 (95%CI:4.67-5.32) allergic conjunctivitis; OR 2.41 (95%CI:2.33-2.52) atopic dermatitis; OR 2.47 (95%CI:2.16-2.82) food allergy, and OR 1.69 (95%CI:1.61-1.78) drug allergy. Interestingly, increased ORs were found for respiratory diseases: 2.06 (95%CI:1.64-2.58) vocal dysfunction; 1.83 (95%CI:1.74-1.92) pneumonia; 1.78 (95%CI:1.73-1.84) sinusitis; 1.71 (95%CI:1.65-1.78) rhinopharyngitis; 2.55 (95%CI:2.03-3.19) obstructive sleep apnea; 1.42 (95%CI:1.25-1.61) pulmonary embolism, and 3.75 (95%CI:1.64-8.53) bronchopulmonary aspergillosis. Asthmatics also suffer from psychiatric, metabolic, cardiac or other comorbidities. Myocardial infarction (OR 0.86, 95%CI:0.79-0.94) did not coexist with asthma. Based on the calculated chances of manifestation for these comorbidities, especially allergic and respiratory, to a lesser extent also metabolic, cardiovascular, and mental disorders should be taken into consideration in the diagnostic and treatment strategy of bronchial asthma.

BRONCHIAL ASTHMA

PREVALENCE OF CO-EXISTING DISEASES IN GERMANY: Patients in Germany with bronchial asthma are highly likely to suffer from co-existing diseases and their treatments should reflect this. Quoc Thai Dinh at Saarland University Hospital in Homburg, Germany, and co-workers conducted a large-scale study of patients presenting with bronchial asthma in the Saarland region between 2009 and 2012. Patients with asthma made up 5.4% of the region's total population, with a higher prevalence occurring in females. They found that bronchial asthma was strongly associated with allergic comorbidities such as rhinitis. Indeed, asthmatic patients had a seven times higher chance to suffer from allergic rhinitis than the rest of the population, and were at higher risk of respiratory diseases like pneumonia and obstructive sleep apnea syndrome. Further associations included cardiovascular, metabolic and mental disorders. Dinh's team call for asthma treatments to take such comorbidities into account.

The branched-chain amino acid transaminase 1 sustains growth of antiestrogen-resistant and ERα-negative breast cancer

Antiestrogen-resistant and triple-negative breast tumors pose a serious clinical challenge because of limited treatment options. We assessed global gene expression changes in antiestrogen-sensitive compared with antiestrogen-resistant (two tamoxifen resistant and two fulvestrant resistant) MCF-7 breast cancer cell lines. The branched-chain amino acid transaminase 1 (BCAT1), which catalyzes the first step in the breakdown of branched-chain amino acids, was among the most upregulated transcripts in antiestrogen-resistant cells. Elevated BCAT1 expression was confirmed in relapsed tamoxifen-resistant breast tumor specimens. High intratumoral BCAT1 levels were associated with a reduced relapse-free survival in adjuvant tamoxifen-treated patients and overall survival in unselected patients. On a tissue microarray (n=1421), BCAT1 expression was detectable in 58% of unselected primary breast carcinomas and linked to a higher Ki-67 proliferation index, as well as histological grade. Interestingly, BCAT1 was predominantly expressed in estrogen receptor-α-negative/human epidermal growth factor receptor-2-positive (ERα-negative/HER-2-positive) and triple-negative breast cancers in independent patient cohorts. The inverse relationship between BCAT1 and ERα was corroborated in various breast cancer cell lines and pharmacological long-term depletion of ERα induced BCAT1 expression in vitro. Mechanistically, BCAT1 indirectly controlled expression of the cell cycle inhibitor p27^Kip1 thereby affecting pRB. Correspondingly, phenotypic analyses using a lentiviral-mediated BCAT1 short hairpin RNA knockdown revealed that BCAT1 sustains proliferation in addition to migration and invasion and that its overexpression enhanced the capacity of antiestrogen-sensitive cells to grow in the presence of antiestrogens. Importantly, silencing of BCAT1 in an orthotopic triple-negative xenograft model resulted in a massive reduction of tumor volume in vivo, supporting our findings that BCAT1 is necessary for the growth of hormone-independent breast tumors.

Long-term Neurological Outcome and Quality of Life after World Federation of Neurosurgical Societies Grades IV and V Aneurysmal Subarachnoid Hemorrhage in an Interdisciplinary Treatment Concept

BACKGROUND: Detailed data on long-term functional outcome of patients with World Federation of Neurosurgical Societies (WFNS) grades IV and V aneurysmal subarachnoid hemorrhages (aSAH) are still scarce.

OBJECTIVE: Assessment of long-term outcome of WFNS IV and V aSAH patients.

METHODS: Functional outcome and quality of life were assessed by the modified Rankin scale (mRS) and the 36-item short-form health survey in consecutively treated aSAH WFNS IV and V patients between 2005 and 2010. Scores from the 36-item short-form health survey were compared to a healthy German population. Prognostic factors were analyzed by uni- and multivariate models.

RESULTS: One hundred and seven eligible patients (median age: 53.0 years) were identified. After interdisciplinary consensus on optimal treatment, aneurysms were obliterated either by clipping (n = 35) or by coiling (n = 72). Ten patients were lost to long-term follow-up; the median clinical follow-up period was 3.2 years for the remaining 97 cases. Twenty-five of 97 died during the acute hospital phase and another 10 patients over the follow-up period leaving 62 long-term survivors. At the end of clinical follow-up, 40/97 patients, including 40/62 of long-term survivors, reached functional independence (mRS ≤ 2). Twelve of 97 patients were moderately (mRS = 3), 10/97 patients were severely disabled (mRS ≥ 4). Younger age (≤ 53 years; P = .001) and radiological absence of cerebral infarction (P = .03) were the strongest predictors for favorable outcome. Quality of life was perceived to be only moderately reduced compared to the healthy control group.

CONCLUSION: Poor-grade aSAH is not necessarily associated with poor long-term functional outcome; after aneurysm repair ∼60% of patients survived and among long-term survivors ∼ 60% regained functional independence.

Miliary pattern of brain metastases - a case report of a hyperacute onset in a patient with malignant melanoma documented by magnetic resonance imaging

Background

Miliary brain metastases are a rare condition but associated with an exceedingly poor prognosis. We present the case of a patient suffering from malignant melanoma with an acute progressively worsening of neurological symptoms up to the loss of consciousness. The magnetic resonance imaging (MRI) demonstrated a new onset of disseminated, miliary spread of central nervous system metastases from a malignant melanoma within 4 days.

Case presentation

We report on a 57-year-old woman suffering from metastatic malignant melanoma positive for BRAF-V600E mutation who developed an acute onset of neurological symptoms. The patient received vemurafenib and dacarbacin as chemotherapeutic regime for treatment of malignant melanoma. After admission to our hospital due to progressive disturbance of memory and speech difficulty a magnetic resonance tomography (MRI) was performed. This showed no evidence of cerebral tumour manifestation. The symptoms progressed until a loss of consciousness occurred on day five after admission and the patient was admitted to our intensive care unit for orotracheal intubation. No evidence for infectious, metabolic or autoimmune cerebral disorders was found. Due to the inexplicable acute worsening of the neurological symptoms a second MRI was performed on day five. This revealed a new onset of innumerable contrast-enhancing miliary lesions, especially in the grey matter which was proven as metastases from malignant melanoma on histopathology.

Conclusion

This case describes an unique hyperacute onset of tumour progression correlating with an acute deterioration of neurological symptoms in a patient suffering from miliary brain metastasis from BRAF positive malignant melanoma.

[Treatment of proximal humerus fractures: relative position of different locking plates to the axillary nerve]

OBJECTIVES

Placement of a proximal humerus locking plate through a percutaneous transdeltoid approach bears the advantages of a minimally invasive approach but may compromise the anterior branches of the axillary nerve. This anatomic study aimed to develop a risk profile for 6 types of modern proximal humerus locking plates as to their interference with the axillary nerve.

MATERIALS AND METHODS

In this study six different implants (Arthrex®, DePuy®, Königsee®, Smith & Nephew®, Stryker® and Synthes®) were placed on the intact proximal humerus of 33 embalmed cadaveric upper extremities and the relative positioning between the axillary nerve and the screw holes was determined.

RESULTS

All locking plates displayed an area of risk which concerned 3 out of 7 (Arthrex®), 4 out of 10 (DePuy®), 2 out of 9 (Königsee®), 3 out of 11 (Smith & Nephew®), 3 out of 11 (Stryker®) and 6 out of 12 (Synthes®) screw holes of the plate.

CONCLUSIONS

Using the anterolateral percutaneous deltoid splitting approach the relative position of the axillary nerve to the holes of a specific implant is of relevance for avoidance of iatrogenic lesions to the nerve.

A randomized placebo-controlled trial of idebenone in Leber's hereditary optic neuropathy

Major advances in understanding the pathogenesis of inherited metabolic disease caused by mitochondrial DNA mutations have yet to translate into treatments of proven efficacy. Leber’s hereditary optic neuropathy is the most common mitochondrial DNA disorder causing irreversible blindness in young adult life. Anecdotal reports support the use of idebenone in Leber’s hereditary optic neuropathy, but this has not been evaluated in a randomized controlled trial. We conducted a 24-week multi-centre double-blind, randomized, placebo-controlled trial in 85 patients with Leber’s hereditary optic neuropathy due to m.3460G>A, m.11778G>A, and m.14484T>C or mitochondrial DNA mutations. The active drug was idebenone 900 mg/day. The primary end-point was the best recovery in visual acuity. The main secondary end-point was the change in best visual acuity. Other secondary end-points were changes in visual acuity of the best eye at baseline and changes in visual acuity for both eyes in each patient. Colour-contrast sensitivity and retinal nerve fibre layer thickness were measured in subgroups. Idebenone was safe and well tolerated. The primary end-point did not reach statistical significance in the intention to treat population. However, post hoc interaction analysis showed a different response to idebenone in patients with discordant visual acuities at baseline; in these patients, all secondary end-points were significantly different between the idebenone and placebo groups. This first randomized controlled trial in the mitochondrial disorder, Leber’s hereditary optic neuropathy, provides evidence that patients with discordant visual acuities are the most likely to benefit from idebenone treatment, which is safe and well tolerated.

[External fixation with motion capacity and radius fractures. Methods and results]

Both the radiocarpal and distal radioulnar joints are often affected in"distal radius fractures". The incidence of this injury increases markedly among women over the age of 40. Bearing in mind the wide variety of distal radius fractures, a fixation system should be used which permits trans- and extra-articular application and subsequent reduction by means of distraction, as well as wrist mobilization. It is important that both reduction and position of the carpal bones can be checked. The possibility of extra-articular (radioradial) fixation should always be considered. AO group A2 and A3 fractures with sufficiently large fragments are suitable for this procedure. In other cases, transarticular application is advised. Complementary measures are justified in the case where two or more cortices in AP and lateral X-rays are destroyed. Adequate implants are also used to stabilize the articular surface. Large bone defects should be filled with corticocancellous material.

Phototrophic transformation of phenol to 4-hydroxyphenylacetate by Rhodopseudomonas palustris

Newly isolated and culture collection strains of Rhodopseudomonas palustris were able to transform phenol to 4-hydroxyphenylacetate under phototrophic conditions in the presence of acetate, malate, benzoate, or cinnamate as growth substrates. The reaction was examined with uniformly (14)C-labelled phenol and the product was identified by HPLC retention time, UV-scans, and (1)H- and (13)C-NMR analysis. The transformation reaction was detectable in cell-free extracts in the presence of NAD(+) and acetyl-CoA. For further degradation of 4-hydroxyphenylacetate by R. palustris, low partial pressures of oxygen were essential, presumably for aerobic aromatic ring fission reactions by mono- and di-oxygenases.

Estrogen induces a rapid secretion of amyloid beta precursor protein via the mitogen-activated protein kinase pathway

The female sex hormone estrogen (17beta-estradiol; E2) may function as a neurohormone and has multiple neuromodulatory functions in the brain. Its potent neuroprotective activities can be dependent and independent of estrogen receptors (ERs). In addition, E2 influences the processing of the amyloid beta precursor protein (APP), one central step in the pathogenesis of Alzheimer's disease. Here, we show: (a) that physiological concentrations of E2 very rapidly cause an increased release of secreted nonamyloidogenic APP (sAPPalpha) in mouse hippocampal HT22 and human neuroblastoma SK-N-MC cells; and (b) that this effect is mediated through E2 via the phosphorylation of extracellular-regulated kinase 1 and 2 (ERK1/2), prominent members of the mitogen-activated protein kinase (MAPK) pathway. Furthermore, we show that the activation of MAPK-signaling pathway and the enhancement of the sAPP release is independent of ERs and could be induced by E2 to a similar extent in neuronal cells either lacking or overexpressing a functional ER.

The female sex hormone oestrogen as neuroprotectant: activities at various levels

The female sex hormone oestradiol (oestrogen) is a steroidal compound that binds to specific intracellular receptors which act as transcription factors. Oestrogen displays many of its effects by the classical mode of action through receptor binding, transactivation and binding to consensus oestrogen response elements on DNA. Although the primary role of oestrogen as an ovarian steroid was thought to be the regulation of sex differentiation and maturation, since oestrogen receptors are expressed in a variety of other tissues besides sex organs, oestrogen is believed to exert multiple activities in several target sites throughout the body, including the nervous system. In the brain oestrogens have multiple activities. Potential neuroprotective functions of oestrogens are being intensively studied and it is becoming increasingly clear that oestrogens are (1) neuroprotective hormones acting via oestrogen receptor-dependent pathways at the genomic level and (2) neuroprotective steroidal structures acting independently of the activation of specific oestrogen receptors. One striking activity of the molecule oestradiol is its intrinsic antioxidant activity which makes it a potential chemical shield for neurons. Nerve cells frequently encounter oxidative challenges during the normal physiology, but also under pathophysiological conditions. Oxidative stress has been implicated in a variety of neurodegenerative disorders including amyotrophic lateral sclerosis, Parkinson's disease and Alzheimer's disease. It is important to stress that the antioxidant neuroprotective activity of oestrogens is independent of oestrogen receptor activation, since oestrogen derivatives and aromatic alcohols that do not bind to oestrogen receptors share the same antioxidant neuroprotective activity. Although this effect of oestrogens can clearly be separated from oestrogen receptor binding, oestrogens may interact with intracellular signalling pathways, such as the mitogen activated protein kinase, cyclic AMP pathways, and with the activity of the redox-sensitive transcription factor NF-kappa B.

The multicomponent reactions and their libraries for natural and preparative chemistry

It was recently recognized that three different types of multi-component reactions (MCRs) exist. In preparative chemistry, the MCRs of type II form their products particularly efficiently. These reactions correspond to equilibria of educts and intermediate products, whose final products are formed practically irreversibly. In recent years, the four component reaction of the isocyanides (U-4CR) of type II and their unions with various reactions and MCRs have become an important industrial process for preparing products and their libraries. It has been demonstrated that all conceivable collections of U-4CR educts can be converted into the corresponding products. In the usual chemical reactions, only the substituents of the products can be varied, whereas the U-4CR and related reactions can also produce skeletally different types of products with diverse substituents. The preparative advantages of forming products by the one-pot MCRs and the great variety of the possible products are illustrated in this review.

A new screen for protein interactions reveals that the Saccharomyces cerevisiae high mobility group proteins Nhp6A/B are involved in the regulation of the GAL1 promoter

The split-ubiquitin assay detects protein interactions in vivo. To identify proteins interacting with Gal4p and Tup1p, two transcriptional regulators, we converted the split-ubiquitin assay into a generally applicable screen for binding partners of specific proteins in vivo. A library of genomic Saccharomyces cerevisiae DNA fragments fused to the N-terminal half of ubiquitin was constructed and transformed into yeast strains carrying either Gal4p or Tup1p as a bait. Both proteins were C-terminally extended by the C-terminal half of ubiquitin followed by a modified Ura3p with an arginine in position 1, a destabilizing residue in the N-end rule pathway. The bait fusion protein alone is stable and enzymatically active. However, upon interaction with its prey, a native-like ubiquitin is reconstituted. RUra3p is then cleaved off by the ubiquitin-specific proteases and rapidly degraded by the N-end rule pathway. In both screens, Nhp6B was identified as a protein in close proximity to Gal4p as well as to Tup1p. Direct interaction between either protein and Nhp6B was confirmed by coprecipitation assays. Genetic analysis revealed that Nhp6B, a member of the HMG1 family of DNA-binding proteins, can influence transcriptional activation as well as repression at a specific locus in the chromosome of the yeast S. cerevisiae.

Insertion of enhanced green fluorescent protein into the lysozyme gene creates mice with green fluorescent granulocytes and macrophages

Pluripotent hematopoietic stem cells have been studied extensively, but the events that occur during their differentiation remain largely uncharted. To develop a system that allows the differentiation of cultured multipotent progenitors by time-lapse fluorescence microscopy, myelomonocytic cells were labeled with green fluorescent protein (GFP) in vivo. This was achieved by knocking the enhanced GFP (EGFP) gene into the murine lysozyme M (lys) locus and using a targeting vector, which contains a neomycin resistant (neo) gene flanked by LoxP sites and "splinked" ends, to increase the frequency of homologous recombination. Analysis of the blood and bone marrow of the lys-EGFP mice revealed that most myelomonocytic cells, especially mature neutrophil granulocytes, were fluorescence-positive, while cells from other lineages were not. Removal of the neo gene through breeding of the mice with the Cre-deleter strain led to an increased fluorescence intensity. Mice with an inactivation of both copies of the lys gene developed normally and were fertile. (Blood. 2000;96:719-726)

A new method for the selection of protein interactions in mammalian cells

In the present study we present a new method that allows for the selection of protein interactions in mammalian cells. We have used this system to verify two interactions previously characterized in vitro. (1) The interaction between human TATA-binding protein 1 and nuclear factor kappaB and (2) the association of Homo sapiens nuclear autoantigen SP100B with human heterochromatin protein 1alpha, a protein implicated in chromatin remodelling. We observe for the first time that these interactions also occur in vivo. One protein was fused to the N-terminal half of ubiquitin, while the interacting partner was fused to the C-terminal half of ubiquitin, that was itself linked to guanine phosphoryltransferase 2 (gpt2) modified to begin with an arginine residue. Upon interaction of both proteins, ubiquitin is reconstituted, and its association with the Rgpt2 reporter is subsequently cleaved off by ubiquitin-processing enzymes. The presence of arginine in the Rgpt2 gene product leads to the degradation of the product by the N-end rule pathway. In the human fibroblast cell line HT1080HPRT(-) (that is deficient in the enzyme for hypoxanthine-guanine phosphoribosyltransferase) cells in which interaction between both proteins of interest occurs can then be selected for by hypoxanthine/aminopterin/thymine medium and counterselected against by 6-thioguanine medium. This method provides a suitable alternative to the yeast two-hybrid system and is generally applicable.

A new class of selective and potent inhibitors of neuronal nitric oxide synthase

The synthesis and SAR of a series of 6-(4-(substituted)phenyl)-2-aminopyridines as inhibitors of nitric oxide synthase are described. Compound 3a from this series shows potent and selective inhibition of the human nNOS isoform, with pharmacokinetics sufficient to provide in vivo inhibition of nNOS activity.

A fast method to diagnose chromosome and plasmid loss in Saccharomyces cerevisiae strains

We have developed a simple, fast and reliable method for the analysis of genetic stability in budding yeast strains. The assay relies on our previous finding that cells expressing the green fluorescent protein (GFP) can be detected and counted by flow cytometric analysis (FACS) (Niedenthal et al., 1996). Expression of a gfp-carrying CEN-plasmid in a wild-type strain resulted in the emission of strong fluorescence from 80% of the cell population. Strong fluorescence and presence of the plasmid, determined by the presence of the URA3 genetic marker, was strictly correlated. Expression of this plasmid in 266 yeast strains, each carrying a complete deletion of a novel, non-essential gene identified in the S. cerevisiae sequencing project, pinpointed 12 strains with an increased level of mitotic plasmid loss. Finally we have shown that measurement of mitotic loss of artificial chromosome fragments equipped with the gfp expression cassette can be performed quantitatively using FACS.

Insulin-like growth factor-1-mediated neuroprotection against oxidative stress is associated with activation of nuclear factor kappaB

The role of insulin-like growth factor 1 (IGF-1) for the treatment of neurodegenerative disorders, such as Alzheimer's disease, has recently gained attention. The present study demonstrates that IGF-1 promotes the survival of rat primary cerebellar neurons and of immortalized hypothalamic rat GT1-7 cells after challenge with oxidative stress induced by hydrogen peroxide (H2O2). Neuroprotective concentrations of IGF-1 specifically induce the transcriptional activity and the DNA binding activity of nuclear factor kappaB (NF-kappaB), a transcription factor that has been suggested to play a neuroprotective role. This induction is associated with increased nuclear translocation of the p65 subunit of NF-kappaB and with degradation of the NF-kappaB inhibitory protein IkappaBalpha. IGF-1-mediated protection of GT1-7 cells against oxidative challenges was mimicked by overexpression of the NF-kappaB subunit c-Rel. Partial inhibition of NF-kappaB baseline activity by overexpression of a dominant-negative IkappaBalpha mutant enhanced the toxicity of H2O2 in GT1-7 cells. The pathway by which IGF-1 promotes neuronal survival and activation of NF-kappaB involves the phosphoinositol (PI) 3-kinase, because both effects of IGF-1 are blocked by LY294002 and wortmannin, two specific PI 3-kinase inhibitors. Taken together, our results provide evidence for a novel molecular link between IGF-1-mediated neuroprotection and induction of NF-kappaB that is dependent on the PI 3-kinase pathway.

All 16 centromere DNAs from Saccharomyces cerevisiae show DNA curvature

All 16 centromere DNA regions of Saccharomyces cerevisiae including 90 bp framing sequences on either side were cloned. These 300 bp long centromere regions were analysed by native polyacrylamide gel electrophoresis and found to display a reduced mobility indicative of DNA curvature. The degree of curvature is centromere dependent. The experimental data were confirmed by computer analysis of the 3-dimensional structure of the CEN DNAs. Altogether these data provide further evidence for a model for budding yeast centromeres in which CEN DNA structure could be important for the assembly, activity and/or regulation of the centromere protein-DNA complex.