Mechanical properties of the human cervical spine as shown by three-dimensional load-displacement curves

STUDY DESIGN

The mechanical properties of multilevel human cervical spines were investigated by applying pure rotational moments to each specimen and measuring multidirectional intervertebral motions.

OBJECTIVES

To document intervertebral main and coupled motions of the cervical spine in the form of load-displacement curves.

SUMMARY OF BACKGROUND DATA

Although a number of in vivo and in vitro studies have attempted to delineate normal movement patterns of the cervical spine, none has explored the complexity of the whole cervical spine as a three-dimensional structure.

METHODS

Sixteen human cadaveric specimens (C0-C7) were used for this study. Pure rotational moments of flexion-extension, bilateral axial torque, and bilateral lateral bending were applied using a specially designed loading fixture. The resulting intervertebral motions were recorded using stereophotogrammetry and depicted as a series of load-displacement curves.

RESULTS

The resulting load-displacement curves were found to be nonlinear, and both rotation and translation motions were coupled with main motions. With flexion-extension moment loading, the greatest degree of flexion occurred at C1-C2 (12.3 degrees), whereas the greatest degree of extension was observed at C0-C1 (20.2 degrees). With axial moment loading, rotation at C1-C2 was the largest recorded (56.7 degrees). With lateral bending moments, the average range of motion for all vertebral levels was 7.9 degrees.

CONCLUSIONS

The findings of the present study are relevant to the clinical practice of examining motions of the cervical spine in three dimensions and to the understanding of spinal trauma and degenerative diseases.

The frequency and impact of ROS1 rearrangement on clinical outcomes in never smokers with lung adenocarcinoma

BACKGROUND

To determine the frequency and predictive impact of ROS1 rearrangements on treatment outcomes in never-smoking patients with lung adenocarcinoma.

PATIENTS AND METHODS

We concurrently analyzed ROS1 and ALK rearrangements and mutations in the epidermal growth factor receptor (EGFR), and KRAS in 208 never smokers with lung adenocarcinoma. ROS1 and ALK rearrangements were identified by fluorescent in situ hybridization.

RESULTS

Of 208 tumors screened, 7 (3.4%) were ROS1 rearranged, and 15 (7.2%) were ALK-rearranged. CD74-ROS1 fusions were identified in two patients using reverse transcriptase-polymerase chain reaction. The frequency of ROS1 rearrangement was 5.7% (6 of 105) among EGFR/KRAS/ALK-negative patients. Patients with ROS1 rearrangement had a higher objective response rate (ORR; 60.0% versus 8.5%; P = 0.01) and a longer median progression-free survival (PFS; not reached versus 3.3 months; P = 0.008) to pemetrexed than those without ROS1/ALK rearrangement. The PFS to EGFR-tyrosine kinase inhibitors in patients harboring ROS1 rearrangement was shorter than those without ROS1/ALK rearrangement (2.5 versus 7.8 months; P = 0.01).

CONCLUSIONS

The frequency of ROS1 rearrangements in clinically selected patients is higher than that reported for unselected patients, suggesting that ROS1 rearrangement is a druggable target in East-Asian never smokers with lung adenocarcinoma. Given the different treatment outcomes to conventional therapies and availability of ROS1 inhibitors, identification of ROS1 rearrangement can lead to successful treatment in ROS1-rearranged lung adenocarcinomas.

p53 gene mutations associated with anaplastic transformation of human thyroid carcinomas

Anaplastic carcinoma of the thyroid gland, which is one of the most aggressive, malignant tumors in humans, is considered to originate from preexisting differentiated thyroid cancer. To define the genetic alterations associated with such progression, we examined nine cases of anaplastic thyroid carcinoma for mutation in exons 4-9 of the p53 tumor suppressor gene. Preliminary screening for mutation by RNase protection analysis demonstrated that two out of nine anaplastic carcinomas contained sequence alterations in the p53 gene. Subsequent DNA sequencing identified the mutated nucleotides in these two cases; one was a nonsense mutation at codon 165, and the other was a single-base deletion at codon 176 resulting in the creation of a stop codon downstream due to frameshift. The fact that no mutations were detected in coexisting foci of papillary carcinomas from the same patients shows that these mutations of the p53 gene occurred after development of papillary carcinomas. These results suggest that p53 gene mutation triggers the progression from differentiated into anaplastic carcinoma in the human thyroid gland.

HER2 status in pure ductal carcinoma in situ and in the intraductal and invasive components of invasive ductal carcinoma determined by fluorescence in situ hybridization and immunohistochemistry

AIM

To determine the HER2 status of ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) of the breast. The increased prevalence of HER2 amplification and overexpression in DCIS is considered to be maintained in the intraductal component of IDC; however, HER2 amplification and overexpression are detected much less in IDC.

METHODS AND RESULTS

Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) were performed to detect HER2 in 270 IDCs with an intraductal component and in 50 pure DCIS samples; IHC was also performed in 116 metastatic nodes. HER2 was found to be amplified in 77 cases (28.5%) and overexpressed in 79 (29.3%) of the 270 IDCs. HER2 amplification was similar between intraductal and invasive components of the same tumour. The concordance for HER2 status between invasive and intraductal components of individual tumours was 98.5% and 99.3% by FISH and IHC, respectively. HER2 was amplified in 25 (50%) of the 50 pure DCIS samples. HER2 overexpression in metastatic nodes resembled the HER2 status in the primary tumour for 108 (93.1%) of 116 cases (kappa =0.831).

CONCLUSION

Our study indicates that the intraductal component of IDC may differ biologically when compared with pure DCIS. HER2 appears to lack a critical role in the progression from DCIS to IDC and HER2 status is maintained in metastatic lesions.

Protection of methamphetamine nigrostriatal toxicity by dietary selenium

Multiple dose administration of methamphetamine (MA) results in long-lasting toxic effects in the nigrostriatal dopaminergic system. These effects are considered to be primarily due to oxidative damage mediated by increased production of hydrogen peroxide or other reactive oxygen species in the dopaminergic system. The present study was designed to determine the protective effects of dietary antioxidant selenium on MA-induced neurotoxicity in the nigrostriatal dopaminergic system. Male C57BL/6J mice were fed either selenium-deficient (< 0.01 ppm Se) or selenium-replete (0.2 ppm Se) diets for 90 days. MA treatment decreased the dopamine (DA) levels in the striatum and substantia nigra (SN) of both Se-replete and Se-deficient animals. However, in Se-replete animals, this DA depletion was significantly attenuated in both the striatum and SN. A novel observation is that MA administration resulted in increased activity of Cu,Zn-SOD in the brains of both Se-deficient and Se-replete animals. However, MA administration to Se-deficient animals exhibited a higher Cu,Zn-SOD activity in the nigrostriatal system than the control animals. Elevated malondialdehyde (MDA) levels in the striatum and SN were also observed in Se-deficient MA-treated animals. Se repletion significantly increased the glutathione peroxidase (GPx) activity and the ratio of reduced glutathione (GSH)/oxidized glutathione (GSSG) in the MA-treated animals. In conclusion, we have shown that dietary Se attenuated methamphetamine neurotoxicity and that this protection involves GPx-mediated antioxidant mechanisms. Even though Cu,Zn-SOD activity was significantly elevated by MA treatment, the role of this enzyme in MA-mediated neurotoxicity is not yet clear.

Ascorbate attenuates trimethyltin-induced oxidative burden and neuronal degeneration in the rat hippocampus by maintaining glutathione homeostasis

The specific role of endogenous glutathione in response to neuronal degeneration induced by trimethyltin (TMT) in the hippocampus was examined in rats. A single injection of TMT (8 mg/kg, i.p.) produced a rapid increase in the formation of hydroxyl radical and in the levels of malondialdehyde (MDA) and protein carbonyl. TMT-induced seizure activity significantly increased after this initial oxidative stress, and remained elevated for up to 2 weeks post-TMT. Although a significant loss of hippocampal Cornus Ammonis CA1, CA3 and CA4 neurons was observed at 3 weeks post-TMT, the elevation in the level of hydroxyl radicals, MDA, and protein carbonyl had returned to near-control levels at that time. In contrast, the ratio of reduced to oxidized glutathione remained significantly decreased at 3 weeks post-TMT, and the glutathione-like immunoreactivity of the pyramidal neurons was decreased. However glutathione-positive glia-like cells proliferated mainly in the CA1, CA3, and CA4 sectors and were intensely immunoreactive. Double labeling demonstrated the co-localization of glutathione-immunoreactive glia-like cells and reactive astrocytes, as indicated by immunostaining for glial fibrillary acidic protein. This suggests that astroglial cells were mobilized to synthesize glutathione in response to the TMT insult. The TMT-induced changes in glutathione-like immunoreactivity appear to be concurrent with changes in the expression levels of glutathione peroxidase and glutathione reductase. Ascorbate treatment significantly attenuated TMT-induced seizures, as well as the initial oxidative stress, impaired glutathione homeostasis, and neuronal degeneration in a dose-dependent manner. These results suggest that ascorbate is an effective neuroprotectant against TMT. The initial oxidative burden induced by TMT may be a causal factor in the generation of seizures, prolonged disturbance of endogenous glutathione homeostasis, and consequent neuronal degeneration.

A cost-effective and rational surgical approach to patients with snoring, upper airway resistance syndrome, or obstructive sleep apnea syndrome

The past decade has seen several innovations in the surgical techniques available for treatment of patients with sleep-disordered breathing. Outpatient techniques such as laser-assisted uvulopalatoplasty (LAUP) and more aggressive procedures designed to address hypopharyngeal and base of tongue obstruction (genioglossus advancement and hyoid myotomy) have been developed and proven successful. We describe the efficacy of LAUP for snoring (72.7%), upper airway resistance syndrome (81.8%), and mild (mean [+/-SD] respiratory disturbance index [RDI] = 12 +/- 8.1) obstructive sleep apnea (41.7%) in 56 patients who underwent 132 LAUP procedures in a 26-month period. Thirty-two patients with more significant obstructive sleep apnea (mean RDI = 41.8 +/- 23.1) underwent multilevel pharyngeal surgery consisting of genioglossus advancement and hyoid myotomy combined with uvulopalatopharyngoplasty. The surgical success rate in this group of patients was 85.7% when commonly accepted criteria were applied. We recommend a stratified surgical approach to patients with sleep-disordered breathing. Progressively worse airway obstruction marked by multilevel pharyngeal collapse and more severe sleep-disordered breathing is treated with incrementally more aggressive surgery addressing multiple areas of the upper airway.

Immunocytochemical evidence that amyloid beta (1-42) impairs endogenous antioxidant systems in vivo

Amyloid beta, the major constituent of the senile plaques in the brains of patients with Alzheimer's disease, is cytotoxic to neurons and has a central role in the pathogenesis of the disease. We have previously demonstrated that potent antioxidants idebenone and alpha-tocopherol prevent learning and memory impairment in rats which received a continuous intracerebroventricular infusion of amyloid beta, suggesting a role for oxidative stress in amyloid beta-induced learning and memory impairment. To test the hypothesis, in the present study, we investigated alterations in the immunoreactivity of endogenous antioxidant systems such as mitochondrial Mn-superoxide dismutase, glutathione, glutathione peroxidase and glutathione-S-transferase following the continuous intracerebroventricular infusion of amyloid beta for 2 weeks. The infusion of amyloid beta (1-42) resulted in a significant reduction of the immunoreactivity of these antioxidant substances in such brain areas as the hippocampus, parietal cortex, piriform cortex, substantia nigra and thalamus although the same treatment with amyloid beta (40-1) had little effect. The alterations induced by amyloid beta (1-42) were not uniform, but rather specific for each immunoreactive substance in a brain region-dependent manner. These results demonstrate a cytological effect of oxidative stress induced by amyloid beta (1-42) infusion. Furthermore, our findings may indicate a heterogeneous susceptibility to the oxidative stress produced by amyloid beta.

Long-term randomized controlled trial of a novel nanopowder hemostatic agent (TC-325) for control of severe arterial upper gastrointestinal bleeding in a porcine model

BACKGROUND AND STUDY AIM

Endoscopic therapy of brisk upper gastrointestinal bleeding remains challenging. A proprietary nanopowder (TC-325) has been proven to be effective in high pressure bleeding from external wounds. The efficacy and safety of TC-325 were assessed in a survival gastrointestinal bleeding animal model.

METHOD

10 animals were randomized to treatment or sham. All animals received intravenous antibiotics, H2-blockers and heparin (activated clotting time 2 × normal). In a sterile laparotomy the gastroepiploic vessels were dissected, inserted through a 1-cm gastrotomy, and freely exposed in the gastric lumen, and the exposed vessel lacerated by needle knife. The treatment group received TC-325 by a modified delivery catheter while the sham group received no endoscopic treatment. Time to hemostasis, and mortality at 60 minutes, 24 hours, 48 hours, and 7 days were noted. Necropsy was performed in all animals.

RESULTS

Spurting arterial bleeding was achieved in all animals. No control animal showed hemostasis within the first hour compared with 100 % (5 / 5) in the treatment arm (mean 13.8 minutes, P < 0.0079). Durable hemostasis was achieved with no evidence of rebleeding after 1 and 24 hours in 80 % (4 / 5) of the treated animals compared with none in the control group ( P < 0.0098). None of the control animals survived more than 6 hours. Necropsy at 1 week in treated animals revealed healed gastrotomy without foreign body granuloma or embolization to the lung or brain.

CONCLUSION

TC-325 is safe and highly effective in achieving hemostasis in an anticoagulated severe arterial gastrointestinal bleeding animal model.

Hydrocele of the canal of Nuck in a girl: ultrasound and MR appearance

Hydrocele of the canal of Nuck is a rare condition in females. A small evagination of parietal peritoneum forms the canal of Nuck. Failure of complete obliteration of the canal results in either an indirect inguinal hernia or a hydrocele of the canal of Nuck. We present a case in a 7-year-old girl. On ultrasound, there was a comma-shaped cyst with the tail directed cranially toward the inguinal canal. The cyst had no internal echoes and demonstrated increased through transmission. Coronal and axial MR showed a thin walled cystic mass.

p21(Waf1/Cip1) and p53 protein expression in breast cancer

p21/Cip1/Waf1 (wild-type p53 activated fragment 1/cyclin-dependent kinase [Cdk]-interacting protein 1) is a prominent Cdk inhibitor and has been shown to be a downstream mediator of p53. In this study, we sought to clarify the clinical significance of Waf1 and the relationship between Waf1 and p53 in breast cancer. For this purpose, the expressions of Waf1 and p53 were evaluated immunohistochemically in a series of 104 patients. Waf1 was expressed in 51 (49%) of 104 tumors tested, and p53 in 33 tumors (32%). Inverse expression of these two proteins was seen in 76 cases (73%); 47 were Waf1-positive and p53-negative, and 29 were Waf1-negative and p53-positive. A comparison with clinicopathologic parameters showed that Waf1 expression correlated with negative lymph nodes (P<.01), a low histologic grade (P<.0001), and positive estrogen receptor status (P<.01). Recurrence-free survival was lower for patients with Waf1-negative tumors than for those with Waf1-positive tumors (P<.0001). In multivariate analysis, Waf1 expression and low histologic grade (1 or 2) tumors had an independent prognostic significance for recurrence-free survival. These results suggest that Waf1 is induced mainly by a p53-dependent pathway and could be a reliable indicator of recurrence in breast cancer.

Phenidone prevents kainate-induced neurotoxicity via antioxidant mechanisms

Acculmulating evidence indicates that a marked generation of oxygen free radicals derived from the metabolism of arachidonic acid causes neurodegeneration. Recently, we have demonstrated that the novel antioxidant actions mediated by phenidone, a dual inhibitor of cyclooxygenase/lipoxygenase pathways, may play a crucial role in preventing neuroexcitotoxicity in vitro [Neurosci. Lett. 272 (1999) 91], and that phenidone significantly attenuates kainic acid (KA)-induced seizures via inhibiting the synthesis of Fos-related antigen protein [Brain Res. 782 (1998) 337]. In order to extend our understanding of the pharmacological intervention of phenidone, we evaluated the antioxidant activity of this compound in vivo in the present study. In order to better understand the significance of a blockade of both the cyclooxygenase and lipoxygenase pathways, we studied the effects of aspirin (ASP; a non-selective inhibitor of cyclooxygenase), NS-398 (a selective inhibitor of cyclooxygenase-2), esculetin (an inhibitor of lipoxygenase) and phenidone on lipid peroxidation, protein oxidation, and glutathione (GSH) status in the rat hippocampus after KA administration. ASP (7.5 or 15 mg/kg), NS-398 (10 or 20 mg/kg), esculetin (5 or 10 mg/kg) or phenidone (25, 50 or 100 mg/kg) was administered orally five times every 12 h before the injection of KA (10 mg/kg, i.p.). The KA-induced toxic behavioral signs, oxidative stress (lipid peroxidation and protein oxidation), impairment of GSH status, and the loss of hippocampal neurons were dose-dependently attenuated by the phenidone, NS-398+esculetin, and ASP+esculetin. However, ASP, NS-398 and esculetin alone failed to protect against the neurotoxicities induced by KA. Therefore, the results suggest that protection by blockade of both cyclooxygenase and lipoxygenase pathways against KA-induced neuroexcitotoxicity is via antioxidant actions. However, a novel anticonvulsant/neuroprotective effect mediated by phenidone remains to be further characterized.

1alpha,25(OH)2D3 and its 3-epimer promote rat lung alveolar epithelial-mesenchymal interactions and inhibit lipofibroblast apoptosis

Although alveolar wall thinning has been attributed to apoptosis of interstitial lung lipofibroblasts (LFs), the underlying molecular mechanism(s) remains unknown. Although the physiological vitamin D steroid hormone 1alpha,25(OH)(2)D(3) (1,25D) has been suggested as a local paracrine/autocrine effector of fetal lung maturation and is known to affect fibroblast apoptosis, its effects on LF apoptosis are unknown. We determined the role of 1,25D and its metabolite, C-3-epimer (3-epi-1,25D), on LF and alveolar type II (ATII) cell differentiation, proliferation, and apoptosis. Embryonic day 19 Sprague-Dawley fetal rat lung LFs and ATII cells were treated with 1,25D or 3-epi-1,25D (1 x 10(-10) to 1 x 10(-8) M) for 24 h, and cell proliferation, apoptosis, and differentiation were assessed. Both 1,25D and 3-epi-1,25D exhibited dose-dependent increases in expression of the key homeostatic epithelial-mesenchymal differentiation markers, increased LF and ATII cell proliferation, and decreased apoptosis. Furthermore, rat pups administered 1,25D from postnatal days 0 to 14 showed increased expressions of key LF and ATII cell differentiation markers, increased Bcl-2-to-Bax ratio as an index of decreased spontaneous alveolar LF and ATII cell apoptosis, increased alveolar count, and a paradoxical increase in septal thickness. We conclude that spatial- and temporal-specific actions of vitamin D play a critical role in perinatal lung maturation by stimulating key alveolar epithelial-mesenchymal interactions and by modulating LF proliferation/apoptosis. These data not only provide the biological rationale for the presence of an alveolar vitamin D paracrine system, but also provide the first integrated molecular mechanism for increased surfactant synthesis and alveolar septal thinning during perinatal lung maturation.

Selenium deficiency potentiates methamphetamine-induced nigral neuronal loss; comparison with MPTP model

The present study was designed to understand the role of an antioxidant, selenium (Se) on methamphetamine (MA)-induced dopaminergic cell damage in the substantia nigra (SN). Male C57BL/6J mice were fed either selenium-deficient (<0.01 ppm Se) or selenium-replete (0.2 ppm Se) diet for 90 days. Se-deficiency potentiates MA-induced reductions of tyrosine hydroxylase-like immunoreactivity (TH-IR), dopamine (DA) and its metabolites, 3, 4-dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA) in the SN. These dopaminergic toxicities were comparable to that induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). By contrast, Se-repletion significantly blocked dopaminergic toxicity after MA treatments. These results suggest that Se-deficient MA-treated mouse is a relevant model of Parkinsonism, and that optimal level of Se plays a crucial role in preventing nigral dopaminergic toxicity induced by MA. However, different mechanisms in the thermoregulation mediated by MA or MPTP remain to be further determined.

Characterization of gastrointestinal bleeding in severely ill hospitalized patients

OBJECTIVE

To characterize the source of bleeding and the prognosis in critically ill patients with upper gastrointestinal hemorrhage that developed while in the hospital.

SETTING

Intensive care units of a large academic tertiary-care center.

DESIGN

Retrospective cohort study.

SUBJECTS

Patients undergoing endoscopy in intensive care units for gastrointestinal bleeding that developed while in the hospital.

MEASUREMENTS AND MAIN RESULTS

Medical records were available for 142 patients. Of these, 66 met the criteria for in-hospital bleeding. Peptic ulcer disease, present in 56% of patients, was the most common bleeding source identified. Of patients with peptic ulcer disease, nine of 37 (24%) had stigmata of recent hemorrhage. Ten patients (15%) received endoscopic hemostasis interventions (eight receiving therapy for bleeding ulcers, two receiving therapy for esophageal varices). The in-hospital mortality rate was 42%. The cause of death was sepsis and/or multiple system organ failure in 21 patients (75%); the gastrointestinal bleeding may have contributed to the onset of sepsis in one of these patients. No patients died directly of gastrointestinal bleeding.

CONCLUSIONS

Critically ill patients who bleed while in the hospital have similar sources of bleeding and rates of endoscopically directed therapy as patients admitted to hospital with bleeding. The mortality rate is very high in patients with bleeding that develops in the hospital, and this is usually a result of systemic disease. These data may help clinicians and patients to estimate the potential benefit of urgent endoscopy in critically ill patients.

Recruitment of the transcriptional machinery through GAL11P: structure and interactions of the GAL4 dimerization domain

The GAL4 dimerization domain (GAL4-dd) is a powerful transcriptional activator when tethered to DNA in a cell bearing a mutant of the GAL11 protein, named GAL11P. GAL11P (like GAL11) is a component of the RNA-polymerase II holoenzyme. Nuclear magnetic resonance (NMR) studies of GAL4-dd revealed an elongated dimer structure with C(2) symmetry containing three helices that mediate dimerization via coiled-coil contacts. The two loops between the three coiled coils form mobile bulges causing a variation of twist angles between the helix pairs. Chemical shift perturbation analysis mapped the GAL11P-binding site to the C-terminal helix alpha3 and the loop between alpha1 and alpha2. One GAL11P monomer binds to one GAL4-dd dimer rendering the dimer asymmetric and implying an extreme negative cooperativity mechanism. Alanine-scanning mutagenesis of GAL4-dd showed that the NMR-derived GAL11P-binding face is crucial for the novel transcriptional activating function of the GAL4-dd on GAL11P interaction. The binding of GAL4 to GAL11P, although an artificial interaction, represents a unique structural motif for an activating region capable of binding to a single target to effect gene expression.

An immunocytochemical study of mitochondrial manganese-superoxide dismutase in the rat hippocampus after kainate administration

We examined the immunocytochemical distribution of mitochondrial Mn-superoxide dismutase (SOD-2) in the rat hippocampus after systemic injection of kainic acid (KA), in order to understand SOD-2-responsible antioxidant defense mechanism during the neurodegenerative process. SOD-2 immunostaining was more intense in CA3 pyramidal neurons than in CA1 neurons in the normal hippocampus. The immunoreactivity in region CA1 was reduced without significant neuronal losses within 12 h of KA injection. The CA1 and CA3 neurons lost their immunoreactivity, whereas SOD-2-positive glia-like cells proliferated, mainly throughout the CA1 sector, and had intense immunoreactivity 3 and 7 days after KA injection. This immunocytochemical distribution of SOD-2-positive non-neuronal elements was similar to that of glial fibrillary acidic protein (GFAP) and S-100 protein-positive cells. Activated microglial cells selectively marked with lectin occurred in the areas affected by the KA-induced lesion. Double-labeling immunocytochemistry showed the co-localization of SOD-2-positive non-neuronal cells and GFAP or S-100 protein-like immunoreactivity in the same cells. This suggests that astroglial cells mobilized to synthesize of SOD-2 protein in a response to KA toxicity designed to reduce the oxidative damage.

Deletion mapping of chromosome 1p and 22q in pheochromocytoma

To identify the localization of tumor suppressor genes, 22 pheochromocytomas (9 hereditary and 13 sporadic) were examined for loss of heterozygosity (LOH) on the short arm of chromosome 1 and on the long arm of chromosome 22 by using 11 polymorphic DNA markers on each chromosome arm. LOH on 1p was observed in 12 of 22 informative cases (55%) and on 22q in 8 of 20 informative cases (40%). There was no significant difference in the frequency of LOH on 1p or 22q between hereditary and sporadic cases. We could localize the commonly deleted regions as distal to D1S73 and proximal to D1S63 on 1p and distal to D22S24 and proximal to D22S1 on 22q. In addition, the relationship between LOH on 1p and 22q was studied in 20 pheochromocytomas which were informative for probes on both chromosome arms. Of eight tumors that showed LOH on 22q, allelic loss on 1p was also detected in seven. Thus, LOH on 22q was correlated significantly with LOH on 1p (P = 0.0249; Fisher's exact test). These results suggest that inactivation of multiple tumor suppressor genes may be required for development and progression of hereditary and non-hereditary pheochromocytoma.

Characterization of a MEN1 ortholog from Drosophila melanogaster

Multiple endocrine neoplasia type 1 (MEN1) is a familial cancer syndrome characterized by tumors of the parathyroid, entero-pancreatic neuroendocrine and pituitary tissues and caused by inactivating mutations in the MEN1 gene. Menin, the 610-amino acid nuclear protein encoded by MEN1, binds to the transcription factor JunD and can repress JunD-induced transcription. We report here the identification of a MEN1 ortholog in Drosophila melanogaster, Menin1, that encodes a 763 amino acid protein sharing 46% identity with human menin. Additionally, 69% of the missense mutations and in-frame deletions reported in MEN1 patients appear in amino acid residues that are identical in the Drosophila and human protein, suggesting the importance of the conserved regions. Drosophila Menin1 gene transcripts use alternative polyadenylation sites resulting in 4.3 and 5-kb messages. The 4.3-kb transcript appears to be largely maternal, while the 5-kb transcript appears mainly zygotic. The binding of Drosophila menin to human JunD or Drosophila Jun could not be demonstrated by the yeast two-hybrid analysis. The identification of the MEN1 ortholog from Drosophila melanogaster will provide an opportunity to utilize Drosophila genetics to enhance our understanding of the function of human menin.

Transcription of the blk gene in human B lymphocytes is controlled by two promoters

Genomic DNA containing the first exon and 5'-flanking region of the human protein tyrosine kinase, blk, was isolated. Sequence analysis identified a TG repeat element in this region with enhancer activity, but no TATA or CCAAT sequences were found. Two blk transcripts of 2.2 and 2.5 kilobases were identified in various B-cell lines by Northern blot analyses, and primer extension experiments demonstrated two clusters of multiple transcription start sites. Subsequent promoter analyses by transient transfection assays with a reporter gene identified two promoter elements in the human blk gene. Promoter P1 contains sequences that have been shown to regulate the expression of immunoglobulin genes and promoter P2 contains elements that are highly conserved in the promoter of major histocompatibility complex class II genes, as well as a B-cell-specific activator protein- (BSAP) binding site. Electrophoretic mobility shift assays demonstrated that the binding of a protein to the BSAP-binding site was correlated with the presence of the 2.5-kilobase blk transcript. These data suggest that the two human blk RNAs arise from the transcription of the blk gene by two distinct promoters and that these promoters may be subject to regulation by different trans-acting factors.

Role of angiography in the evaluation of patients with pulsatile tinnitus

OBJECTIVES/HYPOTHESIS

Pulsatile tinnitus in the face of normal findings on otoscopy is a common otological diagnostic dilemma and can be due to serious vascular malformations such as transverse or sigmoid sinus dural arteriovenous fistula (transverse or sigmoid sinus [TS] DAVF). Left untreated, TS DAVF may result in significant morbidity and mortality. TS DAVF can be suspected or diagnosed with computed tomography (CT), magnetic resonance imaging (MRI), and magnetic resonance angiography (MRA), with the gold standard being angiography. Our objective was to assess the utility of these various diagnostic modalities in the diagnosis of dural arteriovenous fistula.

STUDY DESIGN

Retrospective clinical review.

METHODS

Between 1986 and 1996, 54 patients were evaluated and treated for TS DAVF. Between 1996 and 1999, an additional 33 patients underwent MRI combined with MRA for the evaluation of pulsatile tinnitus. A retrospective review of the medical records for both groups, with special attention to clinical presentation, diagnostic evaluation, therapy, and outcome, was performed.

RESULTS

All patients had pulsatile tinnitus with normal findings on otoscopy. CT scan was relatively insensitive in the detection of TS DAVF. MRI and MR/MRA were significantly more sensitive than CT. In the evaluation of patients with subjective pulsatile tinnitus, MRI/MRA defined anatomical abnormalities that may contribute to pulsatile tinnitus in 63% of patients.

CONCLUSIONS

In the absence of objective pulsatile tinnitus, MRI/MRA is an appropriate initial diagnostic step. When a patient has an objective bruit, the clinician may choose to proceed directly to angiography to make certain that a TS DAVF is not missed.

Dual effects of dextromethorphan on cocaine-induced conditioned place preference in mice

Dextromethorphan (DM) at supra-antitussive doses might produce psychotomimetic effects in humans. In order to understand the underlying mechanisms responsible for the behavior induced by DM, we examined the effects of DM on cocaine-induced conditioned place preference (CPP) and locomotor pattern in mice, and Fos-related antigen immunoreactivity (FRA-IR) in the striatal complex (nucleus accumbens and striatum) of the mouse brain. The effects of DM (20 and 40 mg/kg, i.p.) on the CPP for 2.5, 5, 10, and 20 mg cocaine/kg, i.p. were assessed. Pretreatment with DM dose-dependently decreased the CPP for 20 mg cocaine/kg. Similarly, pretreatment with DM appeared to reduce the CPP for 10 mg cocaine/kg, but increase the CPP for 5 mg cocaine/kg. This finding was more pronounced for 2.5 mg cocaine/kg; DM significantly increased the CPP for 2.5 mg cocaine/kg in a dose-related manner. Furthermore, these results were correlated with alterations in the locomotor pattern (marginal activity) and FRA-IR in the striatal complex. Thus, our results suggest that DM exhibits a biphasic effect on the cocaine-induced CPP and locomotor pattern.

Midkine expression in human breast cancers: expression of truncated form

The expression of midkine (MK), a growth/differentiation factor, was assessed in 34 surgically resected specimens of primary breast cancer or mastopathy. Using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, all of the non-cancerous and cancerous tissues were found to express MK except for one breast cancer specimen. Northern blot analysis revealed that MK mRNA was also expressed in the normal breast tissues examined. Immunohistochemical analysis of the MK protein was performed on a limited number of the specimens, showing that some cancerous tissues were immunoreactive with anti-MK antibodies. Furthermore, using RT-PCR analysis, expression of not only the wild-type but also a truncated form of MK, which was recently found in various human tumor cell lines, was detected in 6 of 26 cancerous tissues but not in non-cancerous tissues.