Ten-year fracture risk predicted by proximal femur Hounsfield units.

Colon cancer screening occurs at younger ages than osteoporosis screening. Bone density measurements using virtual colonoscopy performed for colon cancer screening can provide an early warning sign of patients at potential risk for osteoporosis-related fractures. Earlier identification may improve treatment and potentially fracture prevention. INTRODUCTION: Opportunistic osteoporosis screening with computed tomography colonography (CTC) offers an opportunity to capitalize on earlier colorectal cancer screening to identify patients at risk of future fractures. The purpose of this study is to evaluate 10-year fracture and specifically hip fracture risk based on Hounsfield units (HU) obtained from CTC. METHODS: We identified all CTC scans between 2004 and 2007 of patients 40 years and older with 10 years minimum follow-up. Hounsfield units were measured within the proximal femur and fractures identified via worldwide military records. Patients were stratified into two cohorts based on the presence or lack of a fracture in the wrist, spine, hip, or proximal humerus. Hounsfield unit measurements were compared between groups using Student's t test and the HU threshold was calculated that best approximated an 80% sensitivity to optimally screen patients for fracture risk. The odds ratio, negative predictive value, 10-year incidence of fracture, and survival curves were calculated. RESULTS: We identified 3711 patients with 183 fractures over 10 years. The HU threshold that corresponded with an 80% sensitivity to identify fractures was 112 HU. The negative predictive value (NPV) for overall fractures and hip fractures was over 97%. The 10-year fracture incidence was higher in patients below 112 HU compared to those above for both overall fractures (6.3% vs 1.7%) and hip fractures (2.7% vs 0.07%). The 112 HU threshold corresponds with an odds ratio for overall fracture and hip fractures of 2.5 (95% confidence interval (CI), 1.7-3.6) and 24.5 (95% CI, 3.3-175.5), respectively. CONCLUSION: In the 10 years following CTC, patients who experienced a fracture had lower hip HU. Decreasing HU on CTC may be an early warning sign of fracture potential.

Final report on serial phase II trials of all-intraperitoneal chemotherapy with or without bevacizumab for women with newly diagnosed, optimally cytoreduced carcinoma of Müllerian origin.

BACKGROUND: Intraperitoneal (IP) chemotherapy can improve outcomes for women with optimally cytoreduced epithelial ovarian cancer but toxicities are a concern. We conducted 2 phase 2 trials of an IV/IP regimen using carboplatin and paclitaxel without (Trial A) and with bevacizumab (Trial B). METHODS: Both trials consisted of carboplatin AUC 6 day 1, and paclitaxel 60 mg/m2 on days 1,8, 15 of a 21-day cycle; in Trial B, patients received IV bevacizumab 15 mg/kg every cycle starting cycle 2. Chemotherapy was administered IV for cycle 1 and then IP for all subsequent cycles. Primary objectives included safety and tolerability, pathologic CR rate (Trial A), and the rate of completion of IP cycles of therapy (Trial B). Progression-free (PFS), overall survival (OS), and pharmacokinetic analysis were secondary endpoints. RESULTS: 81 patients were treated on both trials (n = 40 and 41 in trials A and B, respectively). Median age for trials A and B was 59 (range, 36-76) and 55 (range, 19-69) years, respectively. 68% and 85% of patients, respectively for A and B, completed at least 4 cycles of treatment in both trials. Treatment with bevacizumab resulted in higher rates of grade 3 fatigue (37 versus 33%) and grade 3-4 diarrhea (22 versus 8%). Median PFS was 23.5 (95%CI 16.2-35.3) and 25 (95%CI 16.4-42.7) months, respectively; median OS was 68 (95%CI 49.5-NR) and 79.7 (95%CI 59.0-79.7) months, respectively for Trial A and B. CONCLUSIONS: Weekly administered IP carboplatin and IP paclitaxel is tolerable and safe with similar activity with and without concommittant bevacizumab in these 2 trials.

The mechanism producing initial transients on the clarinet.

In self-sustained instruments, starting transients are important timbral characteristics that help identify the instrument and the playing style. Often, the oscillation starts as a growing exponential. This study investigates the starting amplitude of this exponential for the clarinet. After a rapid tongue release, the reed quickly returns to its equilibrium position. The sudden change in aperture produces an abrupt change in both the airflow into the mouthpiece and the mouthpiece pressure. This perturbation travels along the bore and reflects at the open end. Returning to the mouthpiece with slight attenuation, the perturbation can be amplified by the reed acting as an active element-effectively a negative resistance. When the reed release time exceeds the time for sound to travel twice the bore length, the airflow and pressure wave into the bore via the aperture are superposed over their own returning reflection. Measurements of reed motion and mouthpiece pressures during reed release yield values that are used in a model to calculate waveforms showing similarities to those observed experimentally. The initial amplitude decreases with increasing reed release time, though not always monotonically. It can become very small in special cases due to synchronisation between the initial pulse and its reflection.

Mifepristone-inducible transgene expression in neural progenitor cells in vitro and in vivo.

Numerous gene and cell therapy strategies are being developed for the treatment of neurodegenerative disorders. Many of these strategies use constitutive expression of therapeutic transgenic proteins, and although functional in animal models of disease, this method is less likely to provide adequate flexibility for delivering therapy to humans. Ligand-inducible gene expression systems may be more appropriate for these conditions, especially within the central nervous system (CNS). Mifepristone's ability to cross the blood-brain barrier makes it an especially attractive ligand for this purpose. We describe the production of a mifepristone-inducible vector system for regulated expression of transgenes within the CNS. Our inducible system used a lentivirus-based vector platform for the ex vivo production of mifepristone-inducible murine neural progenitor cells that express our transgenes of interest. These cells were processed through a series of selection steps to ensure that the cells exhibited appropriate transgene expression in a dose-dependent and temporally controlled manner with minimal background activity. Inducible cells were then transplanted into the brains of rodents, where they exhibited appropriate mifepristone-inducible expression. These studies detail a strategy for regulated expression in the CNS for use in the development of safe and efficient gene therapy for neurological disorders.

Optimizing the outcome of vascular intervention for Takayasu arteritis.

BACKGROUND: Takayasu arteritis (TA) predisposes to the development of arterial stenoses and aneurysms, and is associated with considerable morbidity and mortality amongst young patients. The aims of this study were to analyse indications and outcomes of surgical intervention, and to assess the potential benefits of immunosuppression and the use of perioperative imaging. METHODS: This was a retrospective review of patients with TA referred between 2001 and 2012. RESULTS: A series of 97 patients with TA, seen at a single tertiary centre, is reported. Immunosuppression was required in 87 patients (90 per cent). Thirty-seven (38 per cent) underwent 64 procedures: 27 patients underwent 33 open surgical procedures and 20 patients had 31 endovascular procedures. After a median follow-up of 6 years, the overall success rate was 79 per cent for open surgery (mean graft patency 9.4 years) and 52 per cent for endovascular procedures (P = 0.035). Procedural failure was significantly reduced in patients receiving preoperative immunosuppression, and particularly endovascular procedures (P = 0.001). In addition to clinical examination and measurement of acute-phase reactants, combination non-invasive imaging including Doppler ultrasonography, [18F]fluorodeoxyglucose combined positron emission and computed tomography (CT), magnetic resonance angiography and CT angiography was used to identify arterial lesions, establish the diagnosis and monitor treatment outcomes. CONCLUSION: Outcomes of vascular intervention in TA may be improved by detailed preoperative assessment including measurement of disease activity, and by ensuring optimal immunomodulatory therapy before and after the procedure.

Herpesvirus vector gene transfer and expression of beta-glucuronidase in the central nervous system of MPS VII mice.

Genetic disorders affecting the central nervous system (CNS) can potentially be treated by gene transfer using vectors which infect and express genes in post-mitotic neurons. Herpesviruses establish latent infections in neurons during which only one viral gene (LAT) is expressed, thus the LAT promoter may express foreign genes in latently infected CNS cells. Expression of a beta-glucuronidase gene driven by the LAT promoter was tested in mice lacking this enzyme, which are a model for a human genetic disease affecting the CNS (mucopolysaccharidosis VII, Sly disease). Cells expressing the missing enzymatic activity were present in the trigeminal ganglia and brainstems of latently infected animals, up to four months post-inoculation, demonstrating the potential of this approach for the long-term expression of foreign genes in the CNS.

Apixaban or Warfarin in Patients with an On-X Mechanical Aortic Valve.

BACKGROUND: Vitamin K antagonists are the only oral anticoagulants approved to prevent valve thrombosis and valve-related thromboembolism in patients with mechanical heart valves. Whether patients with an On-X mechanical aortic valve can be safely anticoagulated with apixaban is unknown. METHODS: Patients with an On-X aortic valve implanted at least 3 months before enrollment were randomly assigned to receive apixaban 5 mg twice daily or warfarin (target international normalized ratio 2.0 to 3.0). The primary efficacy end point was the composite of valve thrombosis or valve-related thromboembolism with coprimary analyses comparing apixaban with warfarin for noninferiority and comparing the apixaban event rate with an objective performance criterion (OPC). RESULTS: The trial was stopped after 863 participants were enrolled owing to an excess of thromboembolic events in the apixaban group. Most (94%) participants took aspirin. A total of 26 primary end-point events occurred, 20 (in 16 participants) in the apixaban group (4.2%/patient-year; 95% confidence interval [CI], 2.3 to 6.0) and 6 (in 6 participants) in the warfarin group (1.3%/patient-year; 95% CI, 0.3 to 2.3). The difference in primary end-point rates between the apixaban and warfarin groups was 2.9 (95% CI, 0.8 to 5.0); noninferiority and OPC success criteria were not met. Major bleeding rates were 3.6%/patient-year with apixaban and 4.5%/patient-year with warfarin. CONCLUSIONS: Apixaban did not demonstrate noninferiority to warfarin and is less effective than warfarin for the prevention of valve thrombosis or thromboembolism in patients with an On-X mechanical aortic valve. (Funded by Artivion; ClinicalTrials.gov number, NCT04142658.)

Flexible optitrode for localized light delivery and electrical recording.

We present optitrode, a miniaturized flexible probe for integrated, localized light delivery and electrical recording. This device features an annular light guide with transparent polymer and fused silica layers surrounding a twisted-wire tetrode. We have developed a novel fabrication process, V-groove guided capillary assembly, to achieve high-precision, coaxial alignment of the various layers of the device. Optitrode with a length-to-diameter ratio ∼500 (5 cm long, 100 µm diameter) has been fabricated, and both the electrical and optical functions have been characterized. The prototype can deliver 11% (110 mW) of the total laser power under abrupt bending angle ∼25°.

Contemporary management of splanchnic and renal artery aneurysms: results of endovascular compared with open surgery from two European vascular centers.

INTRODUCTION: Splanchnic and renal artery aneurysms (SRAAs) are uncommon but potentially life-threatening in case of rupture. Whether these aneurysms are best treated by open repair or endovascular intervention is unknown. The aim of this retrospective study is to report the results of open and endovascular repairs in two European institutions over a fifteen-year period. We have reviewed the available literature published over the 10 last years. METHODS: All patients with SRAAs diagnosed from 1995 to 2010 in St Marys Hospital (London, UK) and Henri Mondor Hospital (Créteil, France) were reviewed. Preoperative clinical and anatomical data, operative management and outcomes were recorded from the charts and analyzed. RESULTS: 40 patients with 51 SRAAs were identified. There were 21 males and 19 females with a mean age of 57 ± 14.9 years. The aneurysms locations were: 14 (27%) renal, 11 (22%) splenic, 7 (14%) celiac trunk, 7 (14%) superior mesenteric artery, 4 (8%) hepatic, 4 (8%) pancreaticoduodenal arcades, 3 (6%) left gastric and 1 (2%) gastroduodenal. 4 patients presented with a ruptured SRAA. 17 SRAAs in 16 patients were treated by open repair, 15 in 15 patients were treated endoluminally and 17 (mean diameter: 18 mm, range: 8-75 mm) were managed conservatively. One patient with metastatic pulmonary cancer with two mycotic aneurysms of the superior mesenteric artery (75 mm) and celiac trunk (15 mm) was palliated. After endovascular treatment, the immediate technical success rate was 100%. There was no significant difference between open repair and endovascular patients in terms of 30-day post-operative mortality rate and peri-operative complications. No in-hospital death occurred in patients treated electively. Postoperatively, four patients (1 ruptured and 3 elective) suffered non-lethal mild to severe complication in the open repair group, as compared with one in the endovascular group (p = .34). The mean length of stay was significantly higher after open repair as compared with endovascular repair (17 days, range: 8-56 days vs. 4 days, range: 2-6; p < .001). The mean follow-up time was 17.8 months (range: 0-143 months) after open repair, 15.8 months (range: 0-121 months) after endovascular treatment, and 24.8 (range: 3-64 months) for patient being managed conservatively. No late death related to the VAA occurred. In each group, 2 successful reoperations were deemed necessary. In the endovascular group, two patients presented a reperfusion of the aneurysmal sac at 6 and 24 months respectively. CONCLUSION: No significant difference in term of 30-day mortality and post-operative complication rates could be identified between open repair and endovascular treatment in the present series. Endovascular treatment is a safe alternative to open repair but patients are exposed to the risk of aneurysmal reperfusion. This mandates careful long-term imaging follow up in patients treated endoluminally.

Decreased lysosomal storage in the adult MPS VII mouse brain in the vicinity of grafts of retroviral vector-corrected fibroblasts secreting high levels of beta-glucuronidase.

A deficiency of beta-glucuronidase (GUSB) causes the multisystem progressive degenerative syndrome, mucopolysaccharidosis (MPS) type VII (Sly disease), which includes mental retardation. Animal homologues of MPS VII (ref. 3, 4) are models for testing somatic gene transfer approaches to treat the central nervous system in this and other lysosomal storage disorders. Previous attempts to correct murine MPS VII by gene therapy have successfully treated lesions in some organs but not in the brain. Other experimental modalities have forestalled some disease progression in the brain, but only if done at birth, before the onset of severe lesions, when the animals are phenotypically normal. We tested whether therapeutic amounts of GUSB could be delivered to the diseased adult brain by transplanting cells engineered to super-secrete the normal enzyme for export to surrounding neural tissues. Lysosomal distention was cleared from neurons and glial cells in the vicinity of the grafts, showing that the secreted enzyme could reach the diseased cells and reverse lesions in the severely diseased brain. The ability to correct established lesions will be important for the treatment of many lysosomal storage diseases affecting the brain, because most patients are not diagnosed until lesions are advanced enough to affect phenotype or developmental milestones in early childhood, and some forms of the diseases do not become apparent until later in life.

Comparable prediction of breast cancer risk from a glimpse or a first impression of a mammogram.

Expert radiologists can discern normal from abnormal mammograms with above-chance accuracy after brief (e.g. 500 ms) exposure. They can even predict cancer risk viewing currently normal images (priors) from women who will later develop cancer. This involves a rapid, global, non-selective process called "gist extraction". It is not yet known whether prolonged exposure can strengthen the gist signal, or if it is available solely in the early exposure. This is of particular interest for the priors that do not contain any localizable signal of abnormality. The current study compared performance with brief (500 ms) or unlimited exposure for four types of mammograms (normal, abnormal, contralateral, priors). Groups of expert radiologists and untrained observers were tested. As expected, radiologists outperformed naïve participants. Replicating prior work, they exceeded chance performance though the gist signal was weak. However, we found no consistent performance differences in radiologists or naïves between timing conditions. Exposure time neither increased nor decreased ability to identify the gist of abnormality or predict cancer risk. If gist signals are to have a place in cancer risk assessments, more efforts should be made to strengthen the signal.

Identification of a variant of gross leukemia virus that induces disease in mice inoculated as adults.

Gross murine leukemia virus normally induces leukemia (thymic lymphoma) in mice inoculated as neonates, but not as adults. We have isolated an apparent variant of this virus which induces thymomas when inoculated i.p. into susceptible adult mice. Using H-2 congenic BALB and C57BL mice, susceptibility to virus-induced thymomagenesis was found to be linked to the H-2 complex. In addition, a radioresistant immune mechanism leading to inhibition of tumor growth was observed in mice with a C57BL but not a BALB background.

PUVA bath therapy strongly suppresses immunological and epidermal activation in psoriasis: a possible cellular basis for remittive therapy.

Psoriasis is characterized by alterations in both the epidermis and dermis of the skin. Epidermal keratinocytes display marked proliferative activation and differentiate along an "alternate" or "regenerative" pathway, while the dermis becomes infiltrated with leukocytes, particularly interleukin 2 (IL-2) receptor-bearing "activated" T cells. Psoralens, administered by the oral route, have therapeutic effects in psoriasis when photochemically activated by ultraviolet A light (PUVA therapy). Recently psoralen bath therapy has been introduced to more effectively deliver this agent to the diseased skin. We have correlated the efficacy of PUVA bath therapy with its effects on specific molecular and cellular parameters of disease, in 10 consecutive patients with recalcitrant psoriasis. Rapid clearing of lesions occurred in 8 out of 10 patients. Biopsies were taken from lesional and nonlesional skin before and after a single round of therapy, and observation was continued in our Clinical Research Center at The Rockefeller University. Enumeration of cycling keratinocytes with the Ki-67 monoclonal antibody showed that PUVA reduced cell proliferation by 73%. The pathological increase in insulin-like growth factor 1 (IGF-1) receptors was reversed, whereas epidermal growth factor (EGF) receptors, which are also increased in psoriasis, remained unchanged. Keratinocyte proteins that are expressed in abnormal sites of the epidermis during psoriasis, i.e., keratin 16, filaggrin, and involucrin, were, after PUVA treatment, localized to their normal sites. Epidermal and dermal T-lymphocytes (CD3+), as well as CD4+, CD8+, and IL-2 receptor+ subsets, were strongly suppressed by PUVA, with virtual elimination of IL-2 receptor+ T cells in some patients. Consistent with diminished lymphocyte activation, HLA-DR expression by epidermal keratinocytes was markedly reduced in treated skin. In comparison to cyclosporine treatment of psoriasis, PUVA therapy leads to more complete reversal of pathological epidermal and lymphocytic activation, changes which we propose to be the cellular basis for a more sustained remission of disease after PUVA treatment.

Successful ultraviolet B treatment of psoriasis is accompanied by a reversal of keratinocyte pathology and by selective depletion of intraepidermal T cells.

Skin irradiation with ultraviolet B (UVB) is a common and often durable treatment for psoriasis and other inflammatory skin disorders. We studied the effects of UVB on keratinocytes and leukocytes in psoriatic tissue and in culture. In nine patients treated repetitively, most of the cellular and molecular changes that typify the psoriatic epidermis reverted to normal. Keratinocyte hyperplasia, assessed by expression of the Ki-67 cell cycle antigen, decreased by 70%, and residual cell proliferation was appropriately confined to the basal layer. Epidermal thickening was reduced by 60%, and a granular layer reformed. Expression of keratin 16, as well as suprabasal integrin alpha 3 and insulin-like growth factor-1 receptors, was eliminated, whereas filagrin increased markedly. UVB also depleted > 90% of the CD3+, CD8+, and CD25+ T cells from the psoriatic epidermis, whereas dermal T cells were only minimally depressed. The latter finding parallels the known inability of these doses of UVB to penetrate the dermis. In tissue culture, UVB was antiproliferative and cytotoxic toward T cells and keratinocytes, but the T cells were 10-fold more sensitive. Furthermore, low doses of UVB induced apoptosis in lymphocytes but not keratinocytes, as detected by the TUNEL (TdT-mediated dUTP-biotin nick end labeling) technique. The selective effects of UVB on intraepidermal T cells in situ and in culture support the hypothesis that epidermal alterations in psoriasis can be normalized by a depletion of activated intraepidermal T cells.

Assessment of surgical competence at carotid endarterectomy under local anaesthesia in a simulated operating theatre.

BACKGROUND: Methods of surgical training that do not put patients at risk are desirable. A high-fidelity simulation of carotid endarterectomy under local anaesthesia was tested as a tool for assessment of vascular surgical competence, as an adjunct to training. METHODS: Sixty procedures were performed by 30 vascular surgeons (ten junior trainees, ten senior trainees and ten consultants) in a simulated operating theatre. Each performed in a non-crisis scenario followed by a crisis scenario. Performance was assessed live by means of rating scales for technical and non-technical skills. RESULTS: There was a significant difference in technical skills with ascending grade for both generic and procedure-specific technical skill scores in both scenarios (P < 0.001 for all comparisons). Similarly, there was also a significant difference in non-technical skill with ascending grade for both scenarios (P < 0.001). There was a highly significant correlation between technical and non-technical performance in both scenarios (non-crisis: r(s) = 0.80, P < 0.001; crisis: r(s) = 0.85, P < 0.001). Inter-rater reliability was high (alpha > or = 0.80 for all scales). CONCLUSION: High-fidelity simulation offers competency-based assessment for all grades and may provide a useful training environment for junior trainees and more experienced surgeons.

Hybrid treatment of complex aortic arch disease with supra-aortic debranching and endovascular stent graft repair.

BACKGROUND: Aortic arch disease has conventionally been the domain of open surgical repair. Hybrid open and endovascular repair has evolved as an alternative, less invasive, treatment option with promising results. A systematic literature review and analysis of the reported outcomes was undertaken. METHODS: An Internet-based literature search using MEDLINE was performed to identify all studies reporting on hybrid aortic arch repair with supra-aortic branch revascularisation and subsequent stent graft deployment. Debranching should involve at least one carotid artery, so that patients merely requiring a carotid-subclavian bypass were not included. Only reports of five patients or more were included in the analysis. Outcome measures were technical success, perioperative, 30-day and late morbidity and mortality. RESULTS: Eighteen studies fulfilled our search criteria, and data from 195 patients were entered for the analysis. No comparative studies of hybrid aortic arch repair with other conventional or innovative treatment modalities were identified. Complete arch repair was performed in 122 patients (63%). The overall technical success rate was 86% (167/195). The most common reason for technical failure was endoleak (9%, 17/195). Overall perioperative morbidity and mortality rates were 21% (41/195) and 9% (18/195), respectively. The most common perioperative complication was stroke (7%, 14/195). Four aneurysm-related deaths were reported during follow-up (2%). No long-term data on hybrid aortic arch repair were identified. CONCLUSIONS: Hybrid repair of complex aortic arch disease is an alternative treatment option with acceptable short-term results. Stroke remains a frequent complication and mortality rates are significant. Further research with large comparative studies and longer follow-up is required.

Hybrid repair of the aortic arch in patients with extensive aortic disease.

OBJECTIVE: To evaluate the outcome of hybrid treatment of the aortic arch with supra-aortic debranching and endovascular stent-graft repair in a selected group of patients with complex disease. DESIGN: Case series study with retrospective analysis of prospectively collected non-randomised data. METHODS: Patients with hybrid repair of complex arch disease at a single centre over a 6-year period were enrolled in the study. Only patients with extensive arch pathologies requiring debranching of at least the left carotid artery were considered. Patients were divided into those who underwent complete and partial supra-aortic revascularisation. The χ2 test was used to evaluate differences in outcomes. Logistic regression analyses were applied to identify predictors of poor outcome. RESULTS: A total of 33 patients were included in the study. Complete and partial arch repair was performed in nine and 24 patients, respectively. The aortic disease extended to the thoracic and abdominal aorta in 39% and 52% of the patients, respectively. One-third of the patients (30%) were treated on an urgent/emergency basis. Elective 30-day mortality and morbidity rates were 13% and 35%, respectively. Early mortality was significantly higher in the complete arch repair group (p=0.046). Pre-existing renal impairment was identified as a poor prognostic factor. All extra-anatomic bypasses remained patent and no aortic disease-related deaths occurred during a mean follow-up period of 23 months (range, 1.5-58 months). Complete arch repair was associated with an increased incidence of late endoleak (p=0.018). CONCLUSIONS: Hybrid treatment of the aortic arch provides a feasible alternative treatment in patients who are high risk for conventional open surgical repair. Careful selection of patients is required to achieve satisfactory results.

Long-term AAV vector gene and protein expression in mouse brain from a small pan-cellular promoter is similar to neural cell promoters.

The neurogenetic, lysosomal enzyme (LSE) deficiency diseases are characterized by storage lesions throughout the brain; therefore, gene transfer needs to provide widespread distribution of the normal enzyme. Adeno-associated virus (AAV) vectors can be effective in the brain despite limited transduction because LSEs are exported to neighboring cells (cross-correction) to reverse the metabolic deficit. The extent of correction is determined by a combination of the total amount of LSE produced by a vector and the spatial distribution of the vector within the brain. Neuron-specific promoters have been used in the brain because AAV predominantly transduces neurons. However, these promoters are large, using up a substantial amount of the limited cloning capacity of AAV vector genomes. A small promoter that is active in all cells, from the LSE beta-glucuronidase (GUSB), has been used for long-term expression in AAV vectors in the brain but the natural promoter is expressed at very low levels. The amount of LSE exported from a cell is proportional to the level of transcription, thus more active promoters would export more LSE for cross-correction, but direct comparisons have not been reported. In this study, we show that in long-term experiments (>6 months) the GUSB minimal promoter (hGBp) expresses the hGUSB enzyme in brain at similar levels as the neuron-specific enolase promoter or the promoter from the latency-associated transcript of herpes simplex virus. The hGBp minimal promoter thus may be useful for long-term expression in the central nervous system of large cDNAs, bicitronic transcription units, self-complimentary or other designs with size constraints in the AAV vector system.

A possible skeletal substructure of the macronucleus of Tetrahymena.

Upon removal of chromatin from isolated macronuclei of tetrahymena, residual structures are obtained, the organization of which faithfully reflects the distinctive architecture of the macronucleus. Macronuclei are isolated by a new procedure in which cells are lysed by immersion in citric acid and Triton X-100. This method is rapid and efficient and leaves the nuclear structures stripped of nuclear envelope and nucleoli. The remaining interconnected chromatin bodies are structurally differentiated into a dense outer shell and a fibrillar inner core. The fibrillar component is identified as chromatin because it is removed upon digestion with DNase and extraction with 2 M NaCl. The dense shell of the chromatin body is unaffected by the digestion procedure, which leaves a skeletal structure comprised of hollow spherical bodies. Analysis of the protein composition by SDS acrylamide gel electrophoresis before and after digestion with DNase and RNase and high-salt extraction shows that histones are diminished, whereas the nonhistone protein composition remains unchanged. It was found the DNase not only extracts chromatin but also protects the nonchromatin structure from the otherwise disruptive effects of high-salt extraction. The method used for isolating the nuclei also affects the structure remaining after the digestion procedure the citric acid/Triton X-100 method enhances the stability of the interconnected spherical bodies. The results indicate that the method for isolating nuclei and the procedure by which chromatin is extracted are both major factors contributing to the detection of a possible nonchromatin nuclear skeleton.

Recognition and transport of adenine derivatives with synthetic receptors.

Several new synthetic agents show high affinity for binding adenine derivatives. The structures feature complementary hydrogen bonds that cause the molecular chelation of the purine nucleus. The high lipophilicity of the new agents permits the transport of adenosine and deoxyadenosine across organic liquid membranes. The use of synthetic receptors for small biological targets may have application in drug delivery.