Sequences attaching loops of nuclear and mitochondrial DNA to underlying structures in human cells: the role of transcription units

DNA sequences attaching loops of nuclear and mitochondrial DNA to underlying structures in HeLa cells have been cloned and 106 representative clones sequenced; 10 clones containing random genomic fragments served as controls. As chromatin is prone to rearrangement, care was taken to isolate sequences using 'physiological' conditions that did not create additional attachments. Comparison (by Southern blotting) of the concentration of each cloned sequence in 'total' and 'attached' fractions of DNA showed that most clones did contain attached sequences, but even highly-attached sequences were not attached in all cells in the population. Results demonstrated that 28% of clones were derived from three specific parts of the mitochondrial genome and 22% from different parts of the alu repeat. In addition, 41% of clones contained unique nuclear sequences; these contained no more of the motifs found attached to nuclear scaffolds or matrices (ie SARs or MARs) than would be expected from their base composition. No other attachment motif(s) could be identified by sequence analysis. However, Northern blotting showed that all the mitochondrial clones and 76% of clones containing unique sequences were transcribed; the degree of attachment correlated with transcriptional activity. These results are consistent with transcription being responsible for ever-changing attachments in both nuclei and mitochondria.

Paranasal Sinus Computed Tomography Scan Findings in Patients with Cystic Fibrosis

Seventy paranasal sinus computed tomography scans of patients with cystic fibrosis were compared with those of age-matched control groups of randomly selected chronic sinusitis patients without cystic fibrosis to determine whether differences in disease patterns existed. In patients older than 10 years, frontal sinus agenesis and maxilloethmoid sinus opacification were significantly more prevalent in patients with cystic fibrosis than in chronic sinusitis patients without cystic fibrosis. Medial bulging of the lateral nasal wall was significantly greater in patients with cystic fibrosis than in chronic sinusitis patients without cystic fibrosis in patients older than 5 years. On the basis of these findings, a diagnostic triad of radiologic findings for cystic fibrosis detection is presented, as well as its clinical implications.

Paranasal sinus computed tomography scan findings in patients with cystic fibrosis

Seventy paranasal sinus computed tomography scans of patients with cystic fibrosis were compared with those of age-matched control groups of randomly selected chronic sinusitis patients without cystic fibrosis to determine whether differences in disease patterns existed. In patients older than 10 years, frontal sinus agenesis and maxilloethmoid sinus opacification were significantly more prevalent in patients with cystic fibrosis than in chronic sinusitis patients without cystic fibrosis. Medial bulging of the lateral nasal wall was significantly greater in patients with cystic fibrosis than in chronic sinusitis patients without cystic fibrosis in patients older than 5 years. On the basis of these findings, a diagnostic triad of radiologic findings for cystic fibrosis detection is presented, as well as its clinical implications.

4-Picoline-2,2':6',2"-terpyridine-platinum(II) - a potent intercalator of DNA

4-Picoloine-2,2':6',2"-terpyridine-platinum(II) is shown in a ligation assay to unwind and so intercalate into DNA. Circular dichroism is used to determine an equilibrium binding constant of approximately 2 x 10(7) M(-1) for the most stable binding mode of 4-picoline-2,2':6',2"-terpyridine-platinum(II) to poly[d(A-T)2] with a site size of about 4 base pairs, and about 1 x 10(6) M(-1) for a second binding mode with a site size of about 2 base pairs. Fluorescence spectroscopy provides further evidence for the strong equilibrium binding constant of 4-picoline-2,2':6',2"-terpyridine-platinum(II) in that it displaces ethidium bromide bound to DNA. The double positive charge on 4-picoline-2,2':6',2"-terpyridine-platinum(II), together with the intercalative binding mode is probably responsible for the large binding constant.

Mimosine arrests the cell cycle after cells enter S-phase

L-Mimosine (beta-N-[3-hydroxy-4-pyridone]-alpha-aminopropionic acid)--a rare amino acid derived from Mimosa and Leucaena plants--arrests cells reversibly late during G1 phase or at the beginning of S-phase. If mimosine were to arrest cells immediately before S-phase, it would provide a superb tool for the investigation of the initiation of DNA synthesis. Therefore, we reexamined the point of action of mimosine. Mitotic HeLa cells were released into 200 microM mimosine and grown for approximately 10 h to block them, before the cells were permeabilized and the amino acid removed by washing them thoroughly. On addition of the appropriate triphosphates, DNA synthesis-measured by the incorporation of [32P]dTTP--began immediately; as it is known that such permeabilized cells cannot initiate DNA synthesis but can only resume elongating previously initiated chains, mimosine must arrest after DNA synthesis has begun. Moreover, cells grown in mimosine assembled functional replication factories--detected by immunolabeling after incorporation of biotin-dUTP--that were typical of those found early during S-phase. Disappointingly, it seems that mimosine--like aphidocolin--blocks only after cells enter S-phase.

Allergic rhinosinusitis in the pediatric population

Allergic disease is very common in the U.S. population and even more common in children seen by otolaryngologists. Allergy causes or contributes to virtually all of the diseases in the respiratory tract that otolaryngologists, particularly otolaryngic allergists, evaluate and treat. The signs and symptoms of allergic disease in the pediatric patient are reviewed to improve the appreciation of the role of allergy in pediatric otolaryngology. Recent research developments, which are reviewed in detail in this article, underscore the importance of allergic, inflammatory response in rhinosinusitis. The key to long-term therapeutic success, particularly in pediatric rhinosinusitis, is management of the underlying allergic diathesis.

Paranasal sinus disease in patients with cystic fibrosis

The enhanced understanding of the pathophysiology of cystic fibrosis (CF) has advanced significantly the management of this disorder, resulting in both an increased longevity and an improved quality of life. Sinonasal disease is an important aspect of CF. The goal of this article is to provide a current synopsis of CF sinonasal disease with an emphasis on disease symptomatology, physical signs, characteristic radiographic features, and outcome-based management options. When indicated, functional endoscopic sinus surgery has been shown to be a safe and effective treatment option for children with CF.

The structural basis of nuclear function

Most models for transcription and replication involve polymerases that track along the template. We review here experiments that suggest an alternative in which polymerization occurs as the template slides past a polymerase fixed to a large structure in the eukaryotic nucleus--a "factory" attached to a nucleoskeleton. This means that higher-order structure dictates how and when DNA is replicated or transcribed.

Symptom outcome after functional endoscopic sinus surgery in patients with cystic fibrosis: a prospective study

Twenty-nine consecutive patients with cystic fibrosis were offered functional endoscopic sinus surgery. Twenty-six of these patients underwent surgery. A symptom questionnaire was obtained from the patient or parent before surgery. At the end of the study this symptom questionnaire was again administered to the same individual, and 21 completed it. There were 14 male and 7 female patients, with a mean age of 12.3 years and a median age of 8.7 years. Mean follow-up was 34.3 months. Results for the following symptoms were significant: nasal airway obstruction was improved (p < 0.0002), olfactory function was improved (p < 0.0037), purulent nasal discharge was decreased (p < 0.001), and activity level was increased (p < 0.001). Other parameters are also reported in the text. In summary, this study prospectively studies the effects of functional endoscopic sinus surgery on symptoms in patients with cystic fibrosis. The study points out several significant areas of symptom improvement and supports the selective use of functional endoscopic sinus surgery in patients with cystic fibrosis. Indications for surgery are provided.

Effect of partial middle turbinectomy on nasal airflow and resistance

We report the first prospective study of the effect of partial middle turbinectomy on nasal airflow and resistance as measured objectively by active anterior rhinomanometry. Our study group consisted of 31 consecutive patients who underwent functional endoscopic sinus surgery with simultaneous partial middle turbinate resections. We found that all patients had significant improvement in nasal airflow (p < 0.001) and significant decrease in nasal resistance (p < 0.001). Thus we found no deleterious effect on nasal function. Additionally, we reviewed the literature on retrospective series in which patients had received partial middle turbinectomies and found no evidence that nasal function was impaired after surgery. We conclude that partial middle turbinectomy may be performed without adversely altering nasal function, as measured by active anterior rhinomanometry.

Effect of Partial Middle Turbinectomy on Nasal Airflow and Resistance

We report the first prospective study of the effect of partial middle turbinectomy on nasal airflow and resistance as measured objectively by active anterior rhinomanometry. Our study group consisted of 31 consecutive patients who underwent functional endoscopic sinus surgery with simultaneous partial middle turbinate resections. We found that all patients had significant improvement in nasal airflow ( p < 0.001) and significant decrease in nasal resistance ( p < 0.001). Thus we found no deleterious effect on nasal function. Additionally, we reviewed the literature on retrospective series in which patients had received partial middle turbinectomies and found no evidence that nasal function was impaired after surgery. We conclude that partial middle turbinectomy may be performed without adversely altering nasal function, as measured by active anterior rhinomanometry.

Symptom Outcome After Functional Endoscopic Sinus Surgery in Patients with Cystic Fibrosis: A Prospective Study

Twenty-nine consecutive patients with cystic fibrosis were offered functional endoscopic sinus surgery. Twenty-six of these patients underwent surgery. A symptom questionnaire was obtained from the patient or parent before surgery. At the end of the study this symptom questionnaire was again administered to the same individual, and 21 completed it. There were 14 male and 7 female patients, with a mean age of 12.3 years and a median age of 8.7 years. Mean follow-up was 34.3 months. Results for the following symptoms were significant: nasal airway obstruction was improved ( p < 0.0002), olfactory function was improved ( p < 0.0037), purulent nasal discharge was decreased ( p < 0.001), and activity level was increased ( p < 0.001). Other parameters are also reported in the text. In summary, this study prospectively studies the effects of functional endoscopic sinus surgery on symptoms in patients with cystic fibrosis. The study points out several significant areas of symptom improvement and supports the selective use of functional endoscopic sinus surgery in patients with cystic fibrosis. Indications for surgery are provided.

A chromomeric model for nuclear and chromosome structure

The basic structural elements of chromatin and chromosomes are reviewed. Then a model involving only three architectural motifs, nucleosomes, chromatin loops and transcription factories/chromomeres, is presented. Loops are tied through transcription factors and RNA polymerases to factories during interphase and to the remnants of those factories, chromomeres, during mitosis. On entry into mitosis, increased adhesiveness between nucleosomes and between factories drives a ‘sticky-end’ aggregation to the most compact and stable structure, a cylinder of nucleosomes around an axial chromomeric core.

Using critical thinking skills to improve medication administration

Nurses need critical thinking skills to provide competent care. For interventions such as drug administration, a system of critical thinking assists nurses to accomplish tasks safely and efficiently. The use of the "think and apply" model provides nurses with a practical way to integrate critical thinking skills into practice.

Lamin proteins form an internal nucleoskeleton as well as a peripheral lamina in human cells

The nuclear lamina forms a protein mesh that underlies the nuclear membrane. In most mammalian cells it contains the intermediate filament proteins, lamins A, B and C. As their name indicates, lamins are generally thought to be confined to the nuclear periphery. We now show that they also form part of a diffuse skeleton that ramifies throughout the interior of the nucleus. Unlike their peripheral counterparts, these internal lamins are buried in dense chromatin and so are inaccessible to antibodies, but accessibility can be increased by removing chromatin. Knobs and nodes on an internal skeleton can then be immunolabelled using fluorescein- or gold-conjugated anti-lamin A antibodies. These results suggest that the lamins are misnamed as they are also found internally.

On the structure of replication and transcription factories

Recent experiments suggest that active polymerases are concentrated in large structures, 'factories', within eukaryotic nuclei. Data concerning the structure of these factories is reviewed.

Replication factories and nuclear bodies: the ultrastructural characterization of replication sites during the cell cycle

Sites of replication in synchronized HeLa cells were visualized by light and electron microscopy; cells were permeabilized and incubated with biotin-16-dUTP, and incorporation sites were immunolabelled. Electron microscopy of thick resinless sections from which approximately 90% chromatin had been removed showed that most DNA synthesis occurs in specific dense structures (replication factories) attached to a diffuse nucleoskeleton. These factories appear at the end of G1-phase and quickly become active; as S-phase progresses, they increase in size and decrease in number like sites of incorporation seen by light microscopy. Electron microscopy of conventional thin sections proved that these factories are a subset of nuclear bodies; they changed in the same characteristic way and contained DNA polymerase alpha and proliferating cell nuclear antigen. As replication factories can be observed and labelled in non-permeabilized cells, they cannot be aggregation artifacts. Some replication occurs outside factories at discrete sites on the diffuse skeleton; it becomes significant by mid S-phase and later becomes concentrated beneath the lamina.

Sites in human nuclei where damage induced by ultraviolet light is repaired: localization relative to transcription sites and concentrations of proliferating cell nuclear antigen and the tumour suppressor protein, p53

The repair of damage induced in DNA by ultraviolet light involves excision of the damaged sequence and synthesis of new DNA to repair the gap. Sites of such repair synthesis were visualized by incubating permeabilized HeLa or MRC-5 cells with the DNA precursor, biotin-dUTP, in a physiological buffer; then incorporated biotin was immunolabeled with fluorescent antibodies. Repair did not take place at sites that reflected the DNA distribution; rather, sites were focally concentrated in a complex pattern. This pattern changed with time; initially intense repair took place at transcriptionally active sites but when transcription became inhibited it continued at sites with little transcription. Repair synthesis in vitro also occurred in the absence of transcription. Repair sites generally contained a high concentration of proliferating cell nuclear antigen but not the tumour-suppressor protein, p53.

Sites in human nuclei where DNA damaged by ultraviolet light is repaired: visualization and localization relative to the nucleoskeleton

The repair of damage induced in DNA by ultraviolet light involves excision of the damage and then repair synthesis to fill the gap. We investigated the sites of repair synthesis using MRC-5 fibroblasts and HeLa cells in G1 phase. Cells were encapsulated in agarose microbeads to protect them during manipulation, irradiated, incubated to allow repair to initiate, and permeabilized with streptolysin O to allow entry of labelled triphosphates; [32P]dTTP was incorporated into acid-insoluble material in a dose-dependent manner. Incubation with biotin-16-dUTP allowed sites of incorporation to be indirectly immunolabeled using a FITC-conjugated antibody; sites were not diffusely spread throughout nuclei but concentrated in discrete foci. This is similar to sites of S phase activity that are attached to an underlying nucleoskeleton. After treatment with an endonuclease, most repaired DNA electroeluted from beads with chromatin fragments; this was unlike nascent DNA made during S phase and suggests that repaired DNA is not as closely associated with the skeleton. However, the procedure destroyed repair activity, so repaired DNA might be attached in vivo through a polymerase that was removed electrophoretically. Therefore this approach cannot be used to determine decisively whether repair sites are associated with a skeleton in vivo.

Functional endoscopic sinus surgery in patients with chronic sinusitis and asthma

Twenty asthma patients who underwent functional endoscopic sinus surgery for chronic sinusitis were studied. Medical records and questionnaire data for these 20 patients were studied regarding the impact of sinus disease and functional endoscopic sinus surgery on their asthma. We found that 95% reported that their asthma was worsened by their sinus disease (95% confidence interval, 0.74 to 0.99+), and 85% reported that functional endoscopic sinus surgery improved their asthma (0.60 to 0.97). Of the 13 patients who used both inhalers and systemic medication, 53.8% were able to eliminate some of their medication (0.21 to 0.79). Furthermore, 61.5% of these patients had a concomitant reduction in their inhaler use (0.28 to 0.85). All patients (six) who used only inhalers experienced a reduction in their inhaler use (0.54 to 1.00), and two patients were able to eliminate their inhalers completely. One of two patients who were steroid dependent was able to discontinue steroids after surgery. Of patients who used steroids intermittently (13), 53.8% were able to eliminate the use of steroids after surgery (0.21 to 0.79). Patients who required preoperative hospital admissions (4) and emergency room or urgent physician office visits (18) had a 75.0% and 81.3% (p < 0.001) reduction in visits, respectively, after surgery. Because 43% of the cost of asthma is the result of hospitalizations and emergency department/urgent physician office visits, a significant impact on health care costs can be realized with functional endoscopic sinus surgery in this patient population.

Systemic reactions to immunotherapy: the American Academy of Otolaryngic Allergy morbidity and mortality survey

Anaphylaxis may be defined as a systemic, immunoglobulin E-mediated (Gell-Coombs type I) hypersensitivity reaction triggered by exposure to an antigen in a previously sensitized patient. Anaphylaxis may occur in a variety of circumstances; however, when it occurs as the result of immunotherapy, it is of great concern to the practicing allergist. When describing or reporting anaphylaxis relating to immunotherapy, most allergists speak in terms of the types of reactions, local vs. systemic. Germane to this discussion is the use of the term systemic reaction, which can mean anything from mild allergy symptoms resulting from an allergy injection to bradycardia and hypotension (shock). In this article we report serious or significant systemic reactions, which are characterized by any of the following symptoms: urticaria, sneezing or nasal obstruction, throat tightness or congestion, wheezing, and shock (bradycardia or hypotension). There were no fatalities reported from the survey group. The overall reaction rate was 0.3%.

Does transcription by RNA polymerase play a direct role in the initiation of replication?

RNA polymerases have been implicated in the initiation of replication in bacteria. The conflicting evidence for a role in initiation in eukaryotes is reviewed.

RNA polymerase: structural determinant of the chromatin loop and the chromosome

Current models for RNA synthesis involve an RNA polymerase that tracks along a static template. However, research on chromatin loops suggests that the template slides past a stationary polymerase; individual polymerases tie the chromatin fibre into loops and clusters of polymerases determine the basic structure of the interphase and metaphase chromosome. RNA polymerase is then both a player and a manager of the chromosome loop.

Functional endoscopic sinus surgery in patients with normal computed tomography scans

Eighteen patients were operated on by functional endoscopic sinus surgery who had no ostiomeatal unit obstruction on computed tomography scan and had unremarkable paranasal sinuses. These patients also had no apparent ostiomeatal unit obstruction on diagnostic nasal endoscopy. Data were collected on these patients regarding the impact of very limited functional endoscopic sinus surgery on their principal complaint of recurrent sinusitis with facial pain/headache thought to be of sinogenic origin. Sixteen patients (88.9%) had a reduction in the number of sinus infections requiring antibiotic therapy. This reduction was significant at p < 0.0001. Twelve of 14 patients whose facial pain/headache was believed to be of sinogenic origin had a significant reduction in severity (95% confidence interval, 49.2% to 95.3%). We discuss the role of reversible nasal mucosal disease in the pathophysiology of recurrent rhinosinusitis in this patient population. This was a very small, select group of patients who had specific complaints and had had medical treatment failures. This therapy is not recommended for every patient, but only a select few with classic complaints of sinus headaches or recurrent sinusitis and negative computed tomography scans.