Successful Treatment with Dabrafenib/Trametinib of a Malignantly Transformed and Metastasized BRAF V600E Mutant Pleiomorphic Xanthoastrocytoma: A Case Report and Review of the Literature

Introduction

Pleiomorphic xanthoastrocytoma (PXA) is considered a low-grade glioma with a favorable prognosis following surgical resection. We present a case report of a BRAFV600E mutant malignantly transformed and disseminated PXA that was successfully treated with BRAF-/MEK-targeted therapy (dabrafenib/trametinib).

Case Presentation

At the age of 16 years, our patient underwent an initial subtotal resection of a right occipital PXA. Six months later, a reintervention for an asymptomatic tumor recurrence was performed and complete resection was achieved. The patient has been followed up by MRI for 14 years without arguments for recurrence but was lost to follow-up thereafter. At 38 years of age, he presented with a symptomatic local recurrence with extra-cerebral soft tissue extension, for which a third surgical resection was performed. Anatomopathological examination reported a grade 3 anaplastic PXA (aPXA); molecular analysis detected a BRAFV600E mutation. Three months later, before the initiation of radiotherapy, a local tumor recurrence was diagnosed, for which he underwent a fourth surgical resection. Radiotherapy was performed following the surgical debulking. One month after completion of radiotherapy, disease progression was documented including multiple sites of extracranial metastases (skeletal, lung, cervical lymph node, and subcutaneous metastases). Systemic treatment with a combination of BRAF-/MEK-inhibitors (dabrafenib/trametinib) was initiated and resulted in a rapid and deep tumor response (partial response according to RECISTv1.1) and absence of BRAFV600E mutant ctDNA in plasma at 6 weeks after treatment initiation. A near-complete metabolic remission was documented on [18F]FDG-PET/CT 3 months after starting systemic therapy.

Conclusion

We present a rare case of malignant transformation and systemic dissemination of a BRAFV600E mutant PXA, occurring 20 years after the initial diagnosis. This case highlights the importance of long-term follow-up of patients diagnosed with these rare central nervous system tumors that initially are considered benign and also illustrates that BRAF/MEK inhibition can be an effective therapy for BRAFV600E mutated PXA, underscoring the importance of performing molecular genetic profiling of these tumors.

A modified perineal approach for the management of strangulated rectal prolapse: A case report

INTRODUCTION

Conditions associated with increased intraabdominal pressure may lead to rectal prolapse. Like any pathological herniation, rectal prolapse can strangulate if incarcerated. When a patient presents with signs and symptoms of strangulation, emergent surgical intervention is warranted. This report strives to strengthen existing evidence for the use of an Altemeier-type perineal approach as a viable choice for the management of strangulated rectal prolapse in healthy individuals.

PRESENTATION OF CASE

A healthy 70-year-old female presents with worsening rectal pain and an irreducible strangulated rectal prolapse. She is brought to the operating suite for an emergent exploration under anesthesia followed by an Altemeier-type procedure without diverting colostomy. The postoperative course is uneventful, and the patient is discharged on postoperative day three. Upon follow up, the patient reports having normal bowel function, and there is no evidence of recurrence.

DISCUSSION

Rectal prolapse is traditionally managed through either a perineal or transabdominal approach depending on the patient's clinical disposition. Incarcerated prolapse is a precursor to strangulation, and recent case reports have demonstrated the efficacy of the Altemeier procedure (perineal rectosigmoidectomy) to treat strangulated prolapse. Our initial exploration under anesthesia revealed a small section of ischemic rectal mucosa that was proximal to the rectosigmoid junction. As a result, we decided to remain within perineal parameters and perform the resection in an Altemeier-type fashion based on the boundary of ischemia.

CONCLUSION

An Altemeier approach was a reasonable option for emergent surgical management of strangulated rectal prolapse in an otherwise relatively healthy individual. This case has been reported in line with the SCARE criteria (Agha et al. [1]).

Overlapping cortical malformations in patients with pathogenic variants in GRIN1 and GRIN2B

BACKGROUND

Malformations of cortical development (MCDs) have been reported in a subset of patients with pathogenic heterozygous variants in GRIN1 or GRIN2B, genes which encode for subunits of the N-methyl-D-aspartate receptor (NMDAR). The aim of this study was to further define the phenotypic spectrum of NMDAR-related MCDs.

METHODS

We report the clinical, radiological and molecular features of 7 new patients and review data on 18 previously reported individuals with NMDAR-related MCDs. Neuropathological findings for two individuals with heterozygous variants in GRIN1 are presented. We report the clinical and neuropathological features of one additional individual with homozygous pathogenic variants in GRIN1.

RESULTS

Heterozygous variants in GRIN1 and GRIN2B were associated with overlapping severe clinical and imaging features, including global developmental delay, epilepsy, diffuse dysgyria, dysmorphic basal ganglia and hippocampi. Neuropathological examination in two fetuses with heterozygous GRIN1 variants suggests that proliferation as well as radial and tangential neuronal migration are impaired. In addition, we show that neuronal migration is also impaired by homozygous GRIN1 variants in an individual with microcephaly with simplified gyral pattern.

CONCLUSION

These findings expand our understanding of the clinical and imaging features of the 'NMDARopathy' spectrum and contribute to our understanding of the likely underlying pathogenic mechanisms leading to MCD in these patients.

Assessing Tumor-Infiltrating Lymphocytes in Breast Cancer: A Proposal for Combining Immunohistochemistry and Gene Expression Analysis to Refine Scoring

Scoring of tumor-infiltrating lymphocytes (TILs) in breast cancer specimens has gained increasing attention, as TILs have prognostic and predictive value in HER2+ and triple-negative breast cancer. We evaluated the intra- and interrater variability when scoring TILs by visual inspection of hematoxylin and eosin-stained tissue sections. We further addressed whether immunohistochemical staining of these sections for immune cell surface markers CD45, CD3, CD4, and CD8 and combination with nanoString nCounter® gene expression analysis could refine TIL scoring. Formalin-fixed paraffin-embedded and fresh-frozen core needle biopsies of 12 female and treatment-naive breast cancer patients were included. Scoring of TILs was performed twice by three independent pathologists with a washout period of 3 days. Increasing intra- and interrater variability was observed with higher TIL numbers. The highest reproducibility was observed on tissue sections stained for CD3 and CD8. The latter TIL scores correlated well with the TIL scores obtained through nanoString nCounter® gene expression analysis. Gene expression analysis also revealed 104 and 62 genes that are positively and negatively related to both TIL scores. In conclusion, integration of immunohistochemistry and gene expression analysis is a valuable strategy to refine TIL scoring in breast tumors.

Neuropathology of genetically defined malformations of cortical development-A systematic literature review

AIMS

Malformations of cortical development (MCD) include a heterogeneous spectrum of clinical, imaging, molecular and histopathological entities. While the understanding of genetic causes of MCD has improved with the availability of next-generation sequencing modalities, genotype-histopathological correlations remain limited. This is the first systematic review of molecular and neuropathological findings in patients with MCD to provide a comprehensive overview of the literature.

METHODS

A systematic review was performed between November 2019 and February 2020. A MEDLINE search was conducted for 132 genes previously linked to MCD in order to identify studies reporting macroscopic and/or microscopic findings in patients with a confirmed genetic cause.

RESULTS

Eighty-one studies were included in this review reporting neuropathological features associated with pathogenic variants in 46 genes (46/132 genes, 34.8%). Four groups emerged, consisting of (1) 13 genes with well-defined histological-genotype correlations, (2) 27 genes for which neuropathological reports were limited, (3) 5 genes with conflicting neuropathological features, and (4) 87 genes for which no histological data were available. Lissencephaly and polymicrogyria were reported most frequently. Associated brain malformations were variably present, with abnormalities of the corpus callosum as most common associated feature.

CONCLUSIONS

Neuropathological data in patients with MCD with a defined genetic cause are available only for a small number of genes. As each genetic cause might lead to unique histopathological features of MCD, standardised thorough neuropathological assessment and reporting should be encouraged. Histological features can help improve the understanding of the pathogenesis of MCD and generate hypotheses with impact on further research directions.

A rare cause of postmenopausal hyperandrogenism

We present an unusual case of mucinous cystadenoma presenting with severe virilisation in a postmenopausal woman. A 71-year-old woman was referred to our outpatient endocrinology clinic because of rapidly progressive androgenic alopecia, clitoromegaly and male pattern pubic hair growth for 1 year. Her medical history was unremarkable. The serum testosterone level was 3.35 µg/L (normal range, <0.4 µg/L), and the dehydroepiandrosterone sulfate level was 267 µg/L (normal range, 100-800 µg/L). MRI of the abdomen revealed a 4×4 cm cystic ovarian mass. A bilateral salpingo-oophorectomy was performed, and histopathology showed a unilocular cystic structure with a yellowish content, compatible with mucinous cystadenoma. Postoperative testosterone levels quickly normalised (<0.4 µg/L).Rapidly developing postmenopausal hyperandrogenism easily turns into a diagnostic challenge for the clinician. Hormone-secreting neoplasms of the ovary are most commonly of sex cord stromal derivation, but atypical causes must be recognised as well. Cystadenomas are among the most common benign ovarian neoplasms and are classically considered 'non-functional' tumours. Most of these tumours are asymptomatic and found incidentally on pelvic examination or with ultrasound. To date and to the best of our knowledge, there are only five cases of mucinous adenoma causing virilisation in postmenopausal women identified in the literature. This sixth case adds strength to the link between ovarian mucinous cystadenoma and severe, rapidly progressive hyperandrogenism during menopause. In this case, surgical resection is the treatment of choice.

Genetic heterogeneity of polymicrogyria: study of 123 patients using deep sequencing

Polymicrogyria is a malformation of cortical development characterized by overfolding and abnormal lamination of the cerebral cortex. Manifestations include epilepsy, speech disturbance and motor and cognitive disability. Causes include acquired prenatal insults and inherited and de novo genetic variants. The proportion of patients with polymicrogyria and a causative germline or mosaic variant is not known. The aim of this study was to identify the monogenic causes of polymicrogyria in a heterogeneous cohort of patients reflective of specialized referral services. Patients with polymicrogyria were recruited from two clinical centres in Australia and Belgium. Patients with evidence of congenital cytomegalovirus infection or causative chromosomal copy number variants were excluded. One hundred and twenty-three patients were tested using deep sequencing gene panels including known and candidate genes for malformations of cortical development. Causative and potentially causative variants were identified and correlated with phenotypic features. Pathogenic or likely pathogenic variants were identified in 25/123 (20.3%) patients. A candidate variant was identified for an additional patient but could not be confirmed as de novo, and therefore it was classified as being of uncertain significance with high clinical relevance. Of the 22 dominant variants identified, 5 were mosaic with allele fractions less than 0.33 and the lowest allele fraction 0.09. The most common causative genes were TUBA1A and PIK3R2. The other eleven causative genes were PIK3CA, NEDD4L, COL4A1, COL4A2, GPSM2, GRIN2B, WDR62, TUBB3, TUBB2B, ACTG1 and FH. A genetic cause was more likely to be identified in the presence of an abnormal head size or additional brain malformations suggestive of a tubulinopathy, such as dysmorphic basal ganglia. A gene panel test provides greater sequencing depth and sensitivity for mosaic variants than whole exome or genome sequencing but is limited to the genes included, potentially missing variants in newly discovered genes. The diagnostic yield of 20.3% indicates that polymicrogyria may be associated with genes not yet known to be associated with brain malformations, brain-specific somatic mutations or non-genetic causes.

Defining the clinical, molecular and imaging spectrum of adaptor protein complex 4-associated hereditary spastic paraplegia

Bi-allelic loss-of-function variants in genes that encode subunits of the adaptor protein complex 4 (AP-4) lead to prototypical yet poorly understood forms of childhood-onset and complex hereditary spastic paraplegia: SPG47 (AP4B1), SPG50 (AP4M1), SPG51 (AP4E1) and SPG52 (AP4S1). Here, we report a detailed cross-sectional analysis of clinical, imaging and molecular data of 156 patients from 101 families. Enrolled patients were of diverse ethnic backgrounds and covered a wide age range (1.0-49.3 years). While the mean age at symptom onset was 0.8 ± 0.6 years [standard deviation (SD), range 0.2-5.0], the mean age at diagnosis was 10.2 ± 8.5 years (SD, range 0.1-46.3). We define a set of core features: early-onset developmental delay with delayed motor milestones and significant speech delay (50% non-verbal); intellectual disability in the moderate to severe range; mild hypotonia in infancy followed by spastic diplegia (mean age: 8.4 ± 5.1 years, SD) and later tetraplegia (mean age: 16.1 ± 9.8 years, SD); postnatal microcephaly (83%); foot deformities (69%); and epilepsy (66%) that is intractable in a subset. At last follow-up, 36% ambulated with assistance (mean age: 8.9 ± 6.4 years, SD) and 54% were wheelchair-dependent (mean age: 13.4 ± 9.8 years, SD). Episodes of stereotypic laughing, possibly consistent with a pseudobulbar affect, were found in 56% of patients. Key features on neuroimaging include a thin corpus callosum (90%), ventriculomegaly (65%) often with colpocephaly, and periventricular white-matter signal abnormalities (68%). Iron deposition and polymicrogyria were found in a subset of patients. AP4B1-associated SPG47 and AP4M1-associated SPG50 accounted for the majority of cases. About two-thirds of patients were born to consanguineous parents, and 82% carried homozygous variants. Over 70 unique variants were present, the majority of which are frameshift or nonsense mutations. To track disease progression across the age spectrum, we defined the relationship between disease severity as measured by several rating scales and disease duration. We found that the presence of epilepsy, which manifested before the age of 3 years in the majority of patients, was associated with worse motor outcomes. Exploring genotype-phenotype correlations, we found that disease severity and major phenotypes were equally distributed among the four subtypes, establishing that SPG47, SPG50, SPG51 and SPG52 share a common phenotype, an 'AP-4 deficiency syndrome'. By delineating the core clinical, imaging, and molecular features of AP-4-associated hereditary spastic paraplegia across the age spectrum our results will facilitate early diagnosis, enable counselling and anticipatory guidance of affected families and help define endpoints for future interventional trials.

Defining the phenotypical spectrum associated with variants in TUBB2A

BACKGROUND

Variants in genes belonging to the tubulin superfamily account for a heterogeneous spectrum of brain malformations referred to as tubulinopathies. Variants in TUBB2A have been reported in 10 patients with a broad spectrum of brain imaging features, ranging from a normal cortex to polymicrogyria, while one patient has been reported with progressive atrophy of the cerebellar vermis.

METHODS

In order to further refine the phenotypical spectrum associated with TUBB2A, clinical and imaging features of 12 patients with pathogenic TUBB2A variants, recruited via the international network of the authors, were reviewed.

RESULTS

We report 12 patients with eight novel and one recurrent variants spread throughout the TUBB2A gene but encoding for amino acids clustering at the protein surface. Eleven patients (91.7%) developed seizures in early life. All patients suffered from intellectual disability, and 11 patients had severe motor developmental delay, with 4 patients (36.4 %) being non-ambulatory. The cerebral cortex was normal in five individuals and showed dysgyria of variable severity in seven patients. Associated brain malformations were less frequent in TUBB2A patients compared with other tubulinopathies. None of the patients had progressive cerebellar atrophy.

CONCLUSION

The imaging phenotype associated with pathogenic variants in TUBB2A is highly variable, ranging from a normal cortex to extensive dysgyria with associated brain malformations. For recurrent variants, no clear genotype-phenotype correlations could be established, suggesting the role of additional modifiers.

Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly

NEDD4L encodes an ubiquitin ligase which is expressed in the cortex and ventricular zone of the fetal brain. Missense variants in NEDD4L have been reported in nine patients with periventricular nodular heterotopia (PNH), polymicrogyria, cleft palate, and syndactyly. All reported variants are located in the HECT domain, causing deregulation of signaling pathways, including the AKT/mTOR pathway. Here we describe a first familial case with four affected members with a high degree of intra-familial phenotypic variability. Phenotypic features in the proband consisted of severe neurodevelopmental delay, refractory seizures, bilateral PNH, and perisylvian polymicrogyria. The other family members were less severely affected with mild developmental delay and isolated bilateral PNH. All family members had syndactyly. An unrelated patient presented with severe neurodevelopmental delay, seizures, and hypospadias, expanding the phenotypic spectrum. MRI revealed bilateral PNH and perisylvian polymicrogyria. All tested patients carry the recurrent variant c.623G > A, p.(Arg208Gln) in the WW domain of NEDD4L. The variant in the unrelated patient occurred de novo. This is the first report of a NEDD4L variant located in the WW domain which is probably involved in the recognition of substrates for ligation suggesting a loss of function variant.

Adding abiraterone or docetaxel to long-term hormone therapy for prostate cancer: directly randomised data from the STAMPEDE multi-arm, multi-stage platform protocol

Background

Adding abiraterone acetate with prednisolone (AAP) or docetaxel with prednisolone (DocP) to standard-of-care (SOC) each improved survival in systemic therapy for advanced or metastatic prostate cancer: evaluation of drug efficacy: a multi-arm multi-stage platform randomised controlled protocol recruiting patients with high-risk locally advanced or metastatic PCa starting long-term androgen deprivation therapy (ADT). The protocol provides the only direct, randomised comparative data of SOC + AAP versus SOC + DocP.

Method

Recruitment to SOC + DocP and SOC + AAP overlapped November 2011 to March 2013. SOC was long-term ADT or, for most non-metastatic cases, ADT for ≥2 years and RT to the primary tumour. Stratified randomisation allocated pts 2 : 1 : 2 to SOC; SOC + docetaxel 75 mg/m2 3-weekly×6 + prednisolone 10 mg daily; or SOC + abiraterone acetate 1000 mg + prednisolone 5 mg daily. AAP duration depended on stage and intent to give radical RT. The primary outcome measure was death from any cause. Analyses used Cox proportional hazards and flexible parametric models, adjusted for stratification factors. This was not a formally powered comparison. A hazard ratio (HR) <1 favours SOC + AAP, and HR > 1 favours SOC + DocP.

Results

A total of 566 consenting patients were contemporaneously randomised: 189 SOC + DocP and 377 SOC + AAP. The patients, balanced by allocated treatment were: 342 (60%) M1; 429 (76%) Gleason 8-10; 449 (79%) WHO performance status 0; median age 66 years and median PSA 56 ng/ml. With median follow-up 4 years, 149 deaths were reported. For overall survival, HR = 1.16 (95% CI 0.82-1.65); failure-free survival HR = 0.51 (95% CI 0.39-0.67); progression-free survival HR = 0.65 (95% CI 0.48-0.88); metastasis-free survival HR = 0.77 (95% CI 0.57-1.03); prostate cancer-specific survival HR = 1.02 (0.70-1.49); and symptomatic skeletal events HR = 0.83 (95% CI 0.55-1.25). In the safety population, the proportion reporting ≥1 grade 3, 4 or 5 adverse events ever was 36%, 13% and 1% SOC + DocP, and 40%, 7% and 1% SOC + AAP; prevalence 11% at 1 and 2 years on both arms. Relapse treatment patterns varied by arm.

Conclusions

This direct, randomised comparative analysis of two new treatment standards for hormone-naïve prostate cancer showed no evidence of a difference in overall or prostate cancer-specific survival, nor in other important outcomes such as symptomatic skeletal events. Worst toxicity grade over entire time on trial was similar but comprised different toxicities in line with the known properties of the drugs.

Trial registration

Clinicaltrials.gov: NCT00268476.

Porous Silicon-Based Quantum Dot Broad Spectrum Radiation Detector

Silicon is a convenient and inexpensive platform for radiation detection, but has low stopping power for x-rays and gamma-rays with high energy (e.g., 100 keV, as used in computed tomography and digital radiography, or 1 MeV, as desired for detection of nuclear materials). We have effectively increased the stopping power of silicon detectors by producing a layer of porous or micro-machined silicon, and infusing this layer with semiconductor quantum dots made of electron-dense materials. Results of prototype detectors show sensitivity to infrared, visible light, and x-rays, with dark current of less than 1 nA/mm².

Development and rupture of a de novo basilar artery aneurysm after surgical removal of a cerebellar arteriovenous malformation

BACKGROUND

The de novo development of an aneurysm in an previously normal artery is an uncommon event. We describe a patient who developed a de novo bleeding aneurysm of the basilar artery in the three weeks following the surgical removal of a large cerebellar AVM. METHOD-FINDINGS: A 48-year-old man suddenly developed transient headache, vertigo and disturbance of balance. Neuroradiological examinations showed the presence of a large AVM of the right cerebellar hemisphere. The AVM was removed successfully; following the operation there were repeated bleeding episodes at the operating site, requiring surgical evacuation. Three weeks after the AVM removal he suffered from a massive subarachnoid haemorrhage due to the rupture of an aneurysm developed de novo in the basilar artery.

INTERPRETATION

This is the first reported case, to our knowledge, of a de novo aneurysm developed in an artery hemodynamically related to a surgically removed AVM. This complication was probably due to the postoperative hemodynamic changes in the vessels afferent to the AVM, associated with arterial wall dysplasia.

Anti-Yo antibody-positive cerebellar degeneration associated with endometrial carcinoma: case report and review of the literature

Paraneoplastic cerebellar degeneration (PCD) is a rare, severely debilitating disease, often with a rapid onset and progression, which predate the diagnosis of malignancy. Despite characteristic features, diagnosis is commonly difficult and successful therapy, which relies on early instigation of treatment, is rare. Here we present a patient in whom anti-Yo antibody-positive PCD was associated with endometrial carcinoma and an extensive review of the literature outlining the clinical features, pathogenesis and treatment of PCD.

Muscarinic receptors in cell lines from ovarian carcinoma: negative correlation with survival of patients

OBJECTIVES

Tumor cells are similar in many respects to embryonic cells, indicating that embryonic genes are reactivated during malignant growth. In previous studies, we observed muscarinic acetylcholine receptors, which are expressed in embryonic cells during morphogenesis and are also found in human melanomas and melanoma cell lines. We determined the presence of muscarinic receptors in a collection of ovarian tumor cell lines for which clinical data were available.

METHODS

Muscarinic receptor status of 39 cell lines derived from 34 patients was determined by Western blotting.

RESULTS

Twenty-three cell lines were receptor positive, and 16, receptor negative. Kaplan-Meier analysis of receptor status of the tumor cell lines and survival time of patients from which the cell lines were established showed that expression of muscarinic receptors was associated with a reduced probability (P = 0.025) of survival: This is within the range of other established prognostic factors reported in the literature.

CONCLUSIONS

A large percentage of ovarian tumor cell lines express muscarinic receptors. Muscarinic receptor expression is an embryonic trait and is correlated with reduced survival of patients. The results from this study provide further evidence of the involvement of muscarinic receptors in the progression of malignant carcinomas.

Genetic and structural determinants of virus neutralizing antibodies

Neutralizing antibodies (Abs) are the principal protective mechanism against disease caused by reinfection with viruses. Ab-mediated neutralization of viruses is a complex process comprising multiple mechanisms. Every structural aspect of Abs is potentially capable of modulating the level of neutralizing activity or the mechanisms of neutralization. The focus of our laboratory is to understand the genetic and structural basis of Ab-mediated neutralization of human viral pathogens. We demonstrated the unexpected finding that virus antigen-binding fragments of Abs (Fabs) mediate potent virus neutralizing effects in vivo. This work has led to a broad investigation of the importance of the genetics, chemistry, and structure of the combining site to the neutralizing activity of antiviral Abs. Ongoing work in our laboratory reveals that effect or functions specified by the Ab isotype such as polymer formation, interactions with complement, interactions with Fc receptors, and the ability to transcytose mucosal epithelia, also modulate the mechanism and level of neutralizing effects mediated by antiviral Abs.

Radioimmunotherapy of cancer: using monoclonal antibodies to target radiotherapy

After years of pre-clinical and clinical testing monoclonal antibodies (mAbs) finally offer new therapeutic choices for patients with haematological and solid malignancies both as unconjugated antibody and as vectors to target radionuclides in radioimmunotherapy (RIT). In recent years some of the most exciting clinical data have come from the use of RIT in the treatment of lymphoma and haematological malignancies and it would now appear highly likely that RIT will play a major role in the treatment strategies for these diseases. For the solid tumours there has also been considerable progress with RIT and mAbs have become a component of treatment protocols for breast cancer. This review highlights the important recent clinical progress that has been made with clinical RIT and provides some new insights into the important mechanisms of action of RIT in haematological malignancies.

Regulation of GTPases in the bacterial translation machinery

Several GTPases participate in bacterial protein biosynthesis. Initiation factor 2 controls the formation of the ribosomal initiation complex and places initiator fMet-tRNAfMet in the ribosomal P-site. Elongation factors Tu and G are responsible for codon-specific binding of the aminoacyl-tRNA to the A-site, and peptidyl-tRNA to the P-site, respectively, during the elongation phase of protein biosynthesis. Release factor 3, a GTPase which is not ubiquitous, is involved in termination and release of the nascent polypeptide. Other translation factors, including initiation factors 1 and 3, elongation factor Ts, release factors 1 and 2, and ribosomal release factor do not belong to the family of GTP/GDP binding proteins. The guanosine nucleotide binding domains of the GTPases involved in translation are structurally related to the Galpha subunit of heterotrimeric G proteins and to the proteins of the Ras family. We have identified and sequenced all genes coding for translation factors in the extreme thermophile Thermus thermophilus. The proteins were overproduced in Escherichia coli, purified, biochemically characterised and used for crystallisation and structural analysis. Further biochemical investigations were aimed at gaining insight into the molecular mechanism underlying the regulation of the GTPase activity of the translation factors, and to elucidate the role of their ribosomal binding sites in this process.

GDNF improves dopamine function in the substantia nigra but not the putamen of unilateral MPTP-lesioned rhesus monkeys

Microdialysis measurements of dopamine (DA) and DA metabolites were carried out in the putamen and substantia nigra of unilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned rhesus monkeys that received intraventricular injections of vehicle or glial-derived neurotrophic factor (GDNF, 300 microg) 3 weeks prior to the microdialysis studies. Following behavioral measures in the MPTP-lesioned monkeys, they were anesthetized with isoflurane and placed in a stereotaxic apparatus. Magnetic resonance imaging (MRI)-guided sterile stereotaxic procedures were used for implantations of the microdialysis probes. Basal extracellular levels of DA and the DA metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were found to be decreased by >95% in the right putamen of the MPTP-lesioned monkeys as compared to normal animals. In contrast, basal DA levels were not significantly decreased, and DOPAC and HVA levels were decreased by only 65% and 30%, respectively, in the MPTP-lesioned substantia nigra. Significant reductions in d-amphetamine-evoked DA release were also observed in the MPTP-lesioned substantia nigra and putamen of the monkeys as compared to normal animals. A single intraventricular administration of GDNF into one group of MPTP-lesioned monkeys elicited improvements in the parkinsonian symptoms in these animals at 2-3 weeks post-administration. In addition, d-amphetamine-evoked overflow of DA was significantly increased in the substantia nigra but not the putamen of MPTP-lesioned monkeys that had received GDNF. Moreover, post-mortem brain tissue studies showed increases in whole tissue levels of DA and DA metabolite levels primarily within the substantia nigra in MPTP-lesioned monkeys that had received GDNF. Taken together, these data support that single ventricular infusions of GDNF produce improvements in motoric behavior in MPTP-lesioned monkeys that correlate with increases in DA neuronal function that are localized to the substantia nigra and not the putamen.

Initiation factors of protein biosynthesis in bacteria and their structural relationship to elongation and termination factors

Initiation of protein biosynthesis in bacteria requires three initiation factors: initiation factor 1, initiation factor 2 and initiation factor 3. The mechanism by which initiation factors form the 70S initiation complex with initiator fMet-tRNA(fMet) interacting with the initiation codon in the ribosomal P site and the second mRNA codon exposed in the A site is not yet understood. Here, we present a model for the function of initiation factors 1 and 2 that is based on the analysis of sequence homologies, biochemical evidence and the present knowledge of the three-dimensional structures of translation factors and ribosomes. The model predicts that initiation factors 1 and 2 interact with the ribosomal A site mimicking the structure of the elongation factor G. We present data that extend the mimicry hypothesis to initiation factors 1 and 2, originally postulated for the aminoacyl-tRNA x elongation factor Tu x GTP ternary complex, elongation factor G and release factors.

Evidence for mitochondrial metabolism of 7,12-dimethylbenz(a)anthracene in porcine ovaries: comparison with microsomal metabolism

7,12-dimethylbenz(a)anthracene (DMBA) causes necrosis in endocrine organs. DMBA metabolism in follicles and corpora lutea from porcine ovaries was demonstrated not only in the microsomal but also in the mitochondrial fraction, in contrast to what has been found in the rat ovary. Maximal activities were present in these fractions of the corpus luteum, with specific activities of 5.9 and 2.2 pmol/min x mg protein, respectively. DMBA metabolism in mitoplasts, i.e. mitochondrial inner membranes, proved to be more than 10-fold higher than the corresponding activity in the mitochondrial fraction. The purities of the subcellular fractions were assessed by measurements of marker enzymes. 17-42% of the mitochondrial DMBA metabolism was concluded to be due to microsomal contamination. In the mitoplast fraction such contamination was only 0.18-2.8%. Ellipticine and alpha-naphthoflavone reduced the metabolism of DMBA in the luteal microsomal fraction by 95 and 77%, respectively. In mitochondria the inhibition by these agents was 63 and 30%, respectively. Indomethacine and estradiol decreased microsomal DMBA metabolism by 53 and 52%, respectively. In mitochondria the inhibition was 52 and 23%, respectively. None of these inhibitors affected the DMBA metabolism by the mitoplast fraction.

A comparison of the patterns of migration and the destinations of homotopically transplanted neonatal subventricular zone cells and heterotopically transplanted telencephalic ventricular zone cells

The cells arising in the anterior part of the subventricular zone (SVZa) migrate along a well-demarcated pathway which lacks radial glial fibers to the olfactory bulb where they differentiate into interneurons of the granule cell layer or glomerular layer (Luskin, 1993, Neuron 11, 173). To analyze the mechanisms underlying this highly directed migration, we have compared the migratory behavior of unmanipulated SVZa-derived cells to that of homotopically transplanted SVZa cells and of heterotopically transplanted telencephalic ventricular zone (VZ) cells that ordinarily migrate in association with radial glial fibers. To identify the phenotype of the SVZa progenitor cells prior to their transplantation, we characterized them in vitro using cell type-specific markers. After 1 day in culture nearly all the SVZa cells were stained with TuJ1, a neuron-specific marker; only an occasional cell exhibited a glial phenotype as judged by the presence of GFAP-immunoreactivity. This indicates that SVZa cells express a neuronal phenotype. To reveal the spatiotemporal distribution of homotopically transplanted neonatal SVZa cells in a host brain, dissociated SVZa cells from Postnatal Day 0 (P0)-P2 animals were labeled with the lipophilic dye PKH26 or the cell proliferation marker BrdU and implanted into the SVZa of host animals of the same age. Within the first week after transplantation there were vast numbers of labeled cells throughout the pathway. Over the next 2 weeks the labeled cells migrated into the overlying cellular layer of the olfactory bulb and began to differentiate, and within 4 weeks the transplanted cells had reached their final positions in the granule cell and glomerular layers of the olfactory bulb in the same proportions as for unmanipulated SVZa-derived cells. While en route to the olfactory bulb the homotopically transplanted cells never strayed from the migratory pathway. In contrast, heterotopically transplanted VZ cells from the embryonic telencephalon did not undergo migration although they did differentiate. These results demonstrate that the homotopically transplanted SVZa-derived cells adopt a mode of migration indistinguishable from that ordinarily utilized by SVZa-derived neurons and that the VZ cells are unable to decipher the same set of guidance cues.

Neurophysiological monitoring of cranial nerves during posterior fossa surgery

Intraoperative neurophysiological monitoring of cranial nerve functions in surgery for microvascular decompression and tumors of the posterior fossa is important for minimizing risk of permanent damage to the nerves. In particular, intraoperative BAEP and the EMG function of muscle innervated by trigeminal and facial muscle have been found useful. We report here our experiences with intraoperative monitoring of brainstem auditory evoked potentials (BAEP) and EMG recorded from muscles supplied by the trigeminal and facial nerves.

The treatment of spasticity by intrathecal administration of baclofen: a preliminary personal experience

The administration of baclofen, a GABAb agonist, by direct infusion into the CSF by means of a programmable device, may avoid the undesired side effects of the oral administration of both the same and other antispastic drugs while giving a marked reduction of spasticity. The preliminary results on 12 patients show the total efficacy of this procedure in reducing spasticity markedly.

Correlation of apomorphine- and amphetamine-induced turning with nigrostriatal dopamine content in unilateral 6-hydroxydopamine lesioned rats

In the unilateral 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease, controversy exists concerning the use of apomorphine- or D-amphetamine-induced rotations as reliable indicators of nigrostriatal dopamine depletion. Our objective was to evaluate which, if either, drug-induced behavior is more predictive of the extent of nigrostriatal dopamine depletion. Fischer 344 and Sprague-Dawley rats were unilaterally injected with 9 micrograms/4 microliters/4 min 6-hydroxydopamine into the medial forebrain bundle. The animals were behaviorally tested with apomorphine (0.05 mg/kg, s.c.) and D-amphetamine (5.0 mg/kg, s.c.). Following testing, the brains were removed and the right and left striata, substantia nigra and ventral tegmental area were dissected free and quickly frozen at -70 degrees C for analysis of catecholamine content by high performance liquid chromatography coupled with electrochemical detection. Our results indicate that an animal which has greater than a 90% depletion of dopamine in the striatum might not rotate substantially on apomorphine, without a concomitant depletion of > 50% of the DA content in the corresponding substantia nigra. No correlations were seen involving depletions of the ventral tegmental area and the extent of the lesions to the striatum. Submaximally lesioned (75-90% depleted) rats were found to rotate on D-amphetamine but not on apomorphine. In addition, control rats that did not receive lesions were often seen to rotate extensively on D-amphetamine. We therefore conclude that maximal lesions of the striatum and substantia nigra are required to generate rotations demonstrable with low dose apomorphine but not with D-amphetamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Trigeminal neuralgia: new surgical strategies

Presentation of the results of treatment in trigeminal neuralgia, using percutaneous radiofrequency coagulation in 712 cases, percutaneous microcompression in 206 cases, and microvascular decompression in 22 cases. Based on the results the following management strategy is proposed: pts. 65 years or younger = percutaneous balloon compression or, if neuroradiological evidence of neurovascular compression) is given, microvascular decompression. Pts. elder than 65 years = thermorhizotomy. It may be repeated in case of recurrence. If the initial operation was percutaneous compression, the second one should be microvascular decompression or, depending on age or other clinical circumstances of the patient, thermorhizotomy.

Heterosexual transmission of viral hepatitis and cytomegalovirus infection among United States military personnel stationed in the western Pacific

A serosurvey of United States military personnel presenting to a sexually transmitted diseases (STD) clinic or reporting for routine physical examination in the Philippines was conducted to determine the risk factors for hepatitis B (anti-HBc), hepatitis C (anti-HCV), and cytomegalovirus (anti-CMV) infection. Among 470 male study subjects, 74 (15.7%) were positive for anti-HBc, five (1.1%) were positive for anti-HCV, and 232 (49.4%) were positive for anti-CMV. A history of a STD (odds ratio [OR] = 7.7) and contact with a female prostitute (OR = 2.3) were significantly associated with anti-HBc seropositivity after adjusting for age, race/ethnicity, foreign birth, and classification as either a STD or routine examination patient. Anti-CMV seropositivity was significantly associated with a history of a STD (adjusted OR = 2.0). These data suggest that in this military population, heterosexual activity was a risk factor for acquiring hepatitis B and CMV infection. United States military personnel stationed in high-risk areas of the western Pacific, particularly patients presenting to STD clinics, may need to be targeted for hepatitis B vaccination.

Combined serotyping and biotyping of Serratia marcescens

The API (Analytab Products, Inc., New York, N.Y.) biotypes of 117 clinical isolates of Serratia marcescens were determined and fell into 13 different patterns. The O and H antigens were determined by tube agglutination, and 27 serotypes were identified. The biotype and serotype appeared to vary indepently. Serotyping and biotyping combined divided these isolates into 56 different types. There was a problem interpreting the end points for inositol fermentation and urease production, which could affect reproducibility of API biotypes. Biotyping is a simple way of screening for possible nosocomial outbreaks of S. marcescens.