Coherence-preserving quantum bits

Real quantum systems couple to their environment and lose their intrinsic quantum nature through the process known as decoherence. Here we present a method for minimizing decoherence by making it energetically unfavorable. We present a Hamiltonian made up solely of two-body interactions between four two-level systems (qubits) which has a 2-fold degenerate ground state. This degenerate ground state has the property that any decoherence process acting on an individual physical qubit must supply energy from the bath to the system. Quantum information can be encoded into the degeneracy of the ground state and such coherence-preserving qubits will then be robust to local decoherence at low bath temperatures. We show how this quantum information can be universally manipulated and indicate how this approach may be applied to a quantum dot quantum computer.

Predicting survival in idiopathic pulmonary fibrosis: scoring system and survival model

Our purpose was to identify clinical, radiological and physiological (CRP) determinants of survival and to develop a CRP scoring system that predicts survival in newly diagnosed cases of idiopathic pulmonary fibrosis (IPF). The study population consisted of 238 patients with biopsy confirmed usual interstitial pneumonia. For each patient, clinical manifestations, chest radiographs, and pulmonary physiology were prospectively assessed. We used Cox proportional-hazards models to assess the effect of these parameters on survival. The effects of age and smoking were included in the analysis. Survival was related to age, smoking status (longer in current smokers), clubbing, the extent of interstitial opacities and presence of pulmonary hypertension on the chest radiograph, reduced lung volume, and abnormal gas exchange during maximal exercise. A mathematical CRP score for predicting survival was derived from these parameters. We showed that this CRP score correlated with the extent and severity of the important histopathologic features of IPF, i.e., fibrosis, cellularity, the granulation/connective tissue deposition, and the total pathologic derangement. Using these models, clinicians are in a better position to provide prognostic information to patients with IPF and to improve the selection of the most appropriate patients for lung transplantation or other standard or novel therapeutic interventions.

VEGF induces airway epithelial cell proliferation in human fetal lung in vitro

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen involved in normal and abnormal angiogenesis. VEGF mRNA and protein are abundant in distal epithelium of midtrimester human fetal lung. In the present study, we identified immunoreactivity for KDR, a major VEGF-specific receptor, in distal lung epithelial cells of human fetal lung tissue, suggesting a possible autocrine or paracrine regulatory role for VEGF in pulmonary epithelial cell growth and differentiation. Addition of exogenous VEGF to human fetal lung explants resulted in increased epithelium volume density and lumen volume density in the tissues, both morphometric parameters of tissue differentiation. Cellular proliferation demonstrated by bromodeoxyuridine uptake was prominent in distal airway epithelial cells and increased in the VEGF-treated explants. VEGF-treated explants also demonstrated increased surfactant protein (SP) A mRNA, SP-C mRNA, and SP-A protein levels compared with controls. However, SP-B mRNA levels were unaffected by VEGF treatment. [(3)H]choline incorporation into total phosphatidylcholine was increased by VEGF treatment, but incorporation into disaturated phosphatidylcholine was not affected by exogenous VEGF. Based on these observations, we conclude that VEGF may be an important autocrine growth factor for distal airway epithelial cells in the developing human lung.

Ivermectin: effectiveness in lymphatic filariasis

This detailed review of the published studies underlying ivermectin's recent registration for use in lymphatic filariasis (LF) demonstrates the drug's single-dose efficacy (over the range of 20-400 microg/kg) in clearing microfilaraemia associated with both Wuchereria bancrofti and Brugia malayi infections of humans. While doses as low as 20 microg/kg could effect transient microfilarial (mf) clearance, higher dosages induced greater and more sustained mf reduction. The single dose of 400 microg/kg yielded maximal responses, but a number of practical considerations suggest that either 400 microg/kg or 200 microg/kg doses would be acceptable for use in LF control programmes. Associated safety assessments indicate that adverse events, which occur commonly following treatment of microfilaraemic individuals, develop not because of drug toxicity but because of host inflammatory responses to dying microfilariae killed by the ivermectin treatment. Ivermectin is, therefore, a highly effective and generally well tolerated microfilaricide that may soon become an essential component of many public health initiatives to interrupt transmission of lymphatic filarial infection in an effort to eliminate LF globally.

Determinates of functional disability after complex upper extremity trauma

This is a retrospective chart review of 71 patients who were operated on for presumed upper extremity arterial trauma between June 1992 and June 1998. Penetrating trauma occurred in 50 (70%) patients, and blunt trauma in 21 (30%). There were 2 innominate, 6 subclavian, 13 axillary, 26 brachial, 5 radial, 6 ulnar, and 6 multiple arterial injuries. There were 7 negative explorations (4 venous injuries, 2 false-positive angiograms, and 1 branch artery injury). In addition to the vascular injury, 44 patients (69%) had another injury in the extremity, including 8 (12.5%) orthopedic injuries, 12 (19%) nerve injuries, and 24 (37.5%) combination nerve and orthopedic injuries. There were three arterial thromboses, one arterial disruption, and four amputations, resulting in a patency rate and limb salvage rate of 94%. Persistent disability was more common in those patients with blunt injury (p = 0.02) and in those patients with associated neurologic and orthopedic injuries (p < 0.05). Full functional recovery was seen in 21 (33%) patients, while some form of disability was noted in the remaining 67%. The magnitude of the concomitant neurologic injury was the major determinate of functional outcome in this patient population.

Medical management of pediatric chronic sinusitis

Pediatric sinusitis can be a challenging disease to treat, whether by a primary care physician or an otolaryngologist. When initial appropriate therapy fails to resolve the disorder, frustration may develop on the part of the patient, the family, and the physician. In addition to treatment with appropriate antibiotics for a sufficient length of time, other associated conditions that can exacerbate the condition must be considered and addressed as necessary. These may include viral upper respiratory infections, allergic rhinitis, immune deficiencies, asthma, and gastroesophageal reflux disease. Unless all associated conditions have been optimized, treatment of chronic sinusitis will often be unsuccessful. Recognition that there may be another factor contributing to the patient's continuing illness should prompt appropriate evaluation and occasionally referral to appropriate specialists. Except for the unusual pediatric patient with a truly anatomic disorder or an underlying chronic illness such as cystic fibrosis, proper medical management will almost always resolve chronic sinusitis.

The Semaphore crab, Heloecius cordiformis: bio-indication potential for heavy metals in estuarine systems

Although alterations at the organism level in decapod crustaceans on exposure to heavy metals have been evidenced in the laboratory, little examination of metal effects on morphology and population parameters have been explored in a field-based situation. Relationships between morphological parameters, population demography and heavy metal sediment loadings were examined in conjunction with the accumulation of metals in the Semaphore crab, Heloecius cordiformis, in the Port Jackson and Hawkesbury River estuaries, Sydney, Australia. H. cordiformis exhibited sexual dimorphism, with males having larger carapace width, carapace length, chelae length and total mass than females. Sexes were subsequently treated separately to assess morphological differences among locations. Locations that had greater proportions of females with purple chelae and less females in the population tended to have higher sediment metal levels. These relationships were maintained over time, and could be employed as population-level biological indicators of heavy metal stress. Copper and zinc were regulated in the hepatopancreas of H. cordiformis. Lead was accumulated in the hepatopancreas of H. cordiformis in proportion to sediment lead levels, suggesting the species is both an appropriate candidate for bio-indication of lead pollution, and Pb is the main metal linked with population level differences. Accumulation of lead varied between sexes, indicating that sexes must be monitored separately. Smaller males accumulated more lead than larger males, suggesting size is an important consideration for lead accumulation.

A 3'-5' exonuclease in human leukemia cells: implications for resistance to 1-beta -D-arabinofuranosylcytosine and 9-beta -D-arabinofuranosyl-2-fluoroadenine 5'-monophosphate

A 3'-5' exonuclease that excises the nucleotide analogs 1-beta-d-arabinofuranosylcytosine monophosphate and 9-beta-d-arabinofuranosyl-2-fluoroadenine 5'-monophosphate incorporated at 3' ends of DNA was purified from the nuclei of: 1) primary human chronic lymphocytic leukemia cells, 2) primary and established human acute myeloblastic leukemia cells, and 3) lymphocytes obtained from healthy individuals. The activity of this nuclear exonuclease (exoN) is elevated approximately 6-fold in 1-beta-d-arabinofuranosylcytosine-resistant leukemia cells as compared with drug-sensitive cells, and it differs between two healthy individuals and among three leukemia patients. exoN is a 46-kDa monomer, requires 50 mm KCl and 1 mm magnesium for optimal activity, and shows a preference for single-stranded over duplex DNA. Its physical and enzymatic properties indicate that exoN is a previously uncharacterized enzyme whose activity may confer resistance to clinical nucleoside analogs in leukemia cells.

Substrate specificity of the p53-associated 3'-5' exonuclease

p53 exhibits 3'-5' exonuclease activity and the significance of this biochemical function is currently not defined. In order to gain information about the potential role(s) of this exonuclease activity, recombinant and wild-type human p53 was examined for excision of nucleotides from defined synthetic DNA substrates. p53 removes nucleotides threefold faster from single-strand DNA than from DNA duplexes, exhibits a 1.5-fold preference for 3'-terminals of DNA that contain a single nucleotide mispair (mismatch) as compared to correctly paired DNA and efficiently excises nucleotides from 3'-ends of blunt and cohesive (staggered) DNA double-strand breaks. The p53 exonuclease is predominantly non-processive on DNA which is 17 nucleotides long (or shorter) and processive on the longer 30-mers. The processivity of nucleotide excision is decreased in the presence of 50 mM potassium phosphate and eliminated when full-length p53 is replaced with the core domain, comprised of amino acids 82-292. Photoaffinity labeling indicates that (1) p53 monomers, rather than dimers, bind to single-strand forms of these oligomers; (2) complexes between p53 and 30-mers are more stable than those formed with 17-mers. The stability of these complexes determines processivity during nucleotide removal and modulates the 3'-5' exonuclease activity of p53. The relevance of substrate specificity of the p53 exonuclease to DNA repair is discussed.

Defects in nuclear and cytoskeletal morphology and mitochondrial localization in spermatozoa of mice lacking nectin-2, a component of cell-cell adherens junctions

Nectin-2 is a cell adhesion molecule encoded by a member of the poliovirus receptor gene family. This family consists of human, monkey, rat, and murine genes that are members of the immunoglobulin gene superfamily. Nectin-2 is a component of cell-cell adherens junctions and interacts with l-afadin, an F-actin-binding protein. Disruption of both alleles of the murine nectin-2 gene resulted in morphologically aberrant spermatozoa with defects in nuclear and cytoskeletal morphology and mitochondrial localization. Homozygous null males are sterile, while homozygous null females, as well as heterozygous males and females, are fertile. The production by nectin-2(-/-) mice of normal numbers of spermatozoa containing wild-type levels of DNA suggests that Nectin-2 functions at a late stage of germ cell development. Consistent with such a role, Nectin-2 is expressed in the testes only during the later stages of spermatogenesis. The structural defects observed in spermatozoa of nectin-2(-/-) mice suggest a role for this protein in organization and reorganization of the cytoskeleton during spermiogenesis.

Techniques for improving ear definition in microtia reconstruction

Surgeons involved in microtia repair recognize the difficulty in creating a natural appearing ear. One key to successful reconstruction is to provide sufficient relief between the helix, scaphoid fossa and antihelix to create the illusion of thin skin overlying thin cartilage. Problems such as thick skin, hair-bearing skin and poor-quality cartilage serve to frustrate the surgeons attempt to achieve the desired result. Surgical techniques to improve cartilaginous framework definition in microtia repair are discussed.

Osteoinduction using bone morphogenic protein in irradiated tissue

OBJECTIVE

To prove the efficacy of bone morphogenic protein as an osteoinductive agent in irradiated tissue.

DESIGN

Prospective randomized controlled trial designed to test the effectiveness of recombinant bone morphogenic protein 2 (rBMP-2) combined with solid hydroxyapatite disks in an irradiated tissue bed.

SUBJECTS

Eighteen adult, male, white New Zealand rabbits weighing 3.0 to 3.5 kg.

INTERVENTION

The rabbits were randomly divided, with 9 receiving radiation treatment and 9 receiving no radiation treatment. Each animal underwent implantation of 2 hydroxyapatite disks onto the snout at 9 weeks following radiation treatment. One disk was impregnated with rBMP-2 and the other with buffer only. The animals were killed at 3, 6, or 20 weeks after implantation for analysis.

RESULTS

Histological analysis demonstrated that rBMP-2 was equally effective as an osteoinductive agent in the irradiated and nonirradiated tissue. We also found significantly increased new bone formation in the rBMP-2 group vs the buffer group.

CONCLUSIONS

This study supports the potential clinical utility of rBMP-2 and solid hydroxyapatite in irradiated tissue beds. These findings have interesting implications for patients with head and neck cancer who have undergone radiation therapy and need bony reconstruction.

Changes in the use profile of Mectizan: 1987-1997

The usually conservative approach of Merck & Co. to drug development became even more so in the Mectizan (ivermectin, MSD) programme because of adverse experiences following 'extra-label' use in Collie dogs and the discovery of a low threshold for acute neurotoxicity in CF-1 mice. Although a very cautious approach and rapid development programme ensued, Merck remained conservative and excluded children under the age of 5 years, pregnant women, and mother who were nursing children under the age of 3 months from treatment. A subsequent, more relaxed set of standards was based on vast human clinical experience, inadvertent use in hundreds of pregnant women without ill-effect, and new laboratory information indicating that the presence of a protective blood-brain barrier protein component (P-glycoprotein) helped to stop Mectizan from crossing the placenta and from crossing the blood-brain barrier in most animal species, including humans. This has allowed more groups to be included in Mectizan treatments: pregnant women living in areas where the risk of loss of sight because of onchocerciasis is very high; and women who are nursing children as young as 1 week of age. Mass distribution of the drug continues to be largely under community control and the likelihood of serious adverse experiences related to finding a human population with unusually low levels of P-glycoprotein (or no P-glycoprotein) seems remote.

Negligible prevalence of antibodies against Trypanosoma cruzi among blood donors in the southeastern United States

Trypanosoma cruzi, a hemoflagellate, causes Chagas' disease and is endemic throughout Latin America. Increasing Latin American immigration to the United States has enhanced concern about transmission of Chagas' disease by infected donor blood. The insect vector and parasites also have been found in the southeastern United States. Autochthonous infection of several species of wild and domesticated mammals suggests that the general human population also may be at risk. To assess the prevalence of antibodies to T cruzi in humans, randomly selected donor blood was screened. Initial screening was performed by indirect hemagglutination (1:4 initial serum dilution) and at least one of three different enzyme immunoassays. All samples testing positive by at least one screening method were tested by radioimmunoprecipitation and indirect immunofluorescence supplemental methods, which were used for confirmation and calculation of specificity. Of the 6,013 serum samples evaluated, 85 tested positive by one screening method. Only 10 of the samples tested positive by more than one method. The percentages of positive screening tests are 0.05% by indirect hemagglutination and 0.06%, 0.91%, 3.97% by Abbott Laboratories (Abbott Park, Ill), Gull (Gull Laboratories, Salt Lake City, Utah), and Polychaco (Polychaco S.A.I.C., Buenos Aires, Argentina) enzyme immunoassays, respectively. All samples were negative by radioimmunoprecipitation and indirect immunofluorescence. These results suggest that although parasite and vector are found in the southeastern United States and both infect mammals, the risk of natural infection to humans in this region seems to be negligible. There was variation in positivity among different screening methods. The highest percentage of positive results was with the enzyme immunoassay, in which the binding of serum antibodies to antigens is amplified by enzymatic reactions.

Mutagenesis of the Mn2+-binding site of manganese peroxidase affects oxidation of Mn2+ by both compound I and compound II

The present study investigates whether compound I and compound II of manganese peroxidase from the white-rot fungus Phanerochaete chrysosporium utilize the same Mn-binding site for catalysis. Manganese peroxidase was expressed from its cDNA in Escherichia coli and refolded from inclusion bodies to yield fully active enzyme. Three mutants of the enzyme were generated by site-directed mutagenesis. Each of the three amino acid residues proposed to be involved in Mn2+ binding, E35, D179, and E39, was mutated. The acidic side chains of E35 and E39 were shortened by one carbon to the acidic group D, and the acidic side chain of D179 was shortened by one carbon to the alkyl group A. These mutants, E35D, D179A, and E39D, were used to determine whether Mn2+ reacts at the same site with both compound I and compound II of manganese peroxidase and to determine whether phenolic substrates for the enzyme react at this site. Our results conclusively demonstrate that E35 and D179 residues are involved not only in Mn2+ binding but also in electron transfer from Mn2+ to the enzyme for both compound I and compound II. In contrast, E39 is not critically important to either process. None of the three residues is involved in reactions with phenolic substrates or with H2O2.

Industry perspective on clinical trial issues for combination vaccines

The development and production of vaccines remains complicated, largely because of the complexity of the vaccines, which are virtually always manufactured in a biological system; the nature of most vaccines precludes the use of the detailed chemical analysis that is possible for simple chemical entities. Therefore, approval and release of vaccines is dependent upon careful view of the manufacturing processes, the analytical data that are available, and data from clinical trials of consistency lots. The makeup of consistency lots from combinations, the purpose and utility of such lots, and the timing of their production depend not only on the maturity of the manufacturing process but also upon mutual agreement between the sponsor and the regulators. Consistency of application of regulations and precedent are important in the sponsor's ability to carry out successful development programs. The science of adjuvants is still in its infancy, but opportunities for it to mature are legion. Aluminum salts remain the mainstay of contemporary adjuvants but will no doubt be supplanted in the near future. The ethics of doing efficacy studies in infants who could be protected by safe and well-tolerated vaccines must be debated openly. Closely related to efficacy studies are the use of surrogates, which should be developed, recognized, and utilized. Finally, the potential utility of M-M-R IIV was shown by studies of the individual attenuated virus components in vaccines.

New challenges in quality control and licensure. Regulation

The Children's Vaccine Initiative (CVI) will result in profound changes in immunization practice. Before the CVI is fully developed, it will present numerous challenges to regulatory practice that will require new applications of existing ideas and innovative solutions to practical issues, especially in combining existing vaccines.

Recombinant erythropoietin overdose

Deliberate self-administration of recombinant human erythropoietin (rHuEpo) in a patient without anemia has never been documented. The case of a 62-year-old man who worked in an allied health care field and surreptitiously injected the drug, causing his hematocrit to increase to a dangerously high level is presented. Resultant complications of the misuse of erythropoietin in this patient included worsening hypertension, exacerbation of chronic lung disease and development of new onset angina. Medical management consisted of endotracheal intubation with mechanical ventilation, intravenous hydration, and serial phlebotomy. The unusual possibility of erythropoietin abuse must be added to the differential diagnosis with a patient with unexplained polycythemia. This case highlights the potential abuse of biological growth factors that may mask medical conditions.

Blunt trauma-induced pacemaker failure

A 54-year-old man with an artificial pacemaker sustained blunt trauma to his chest when he was struck with a baseball bat. Within 15 minutes after the injury, the patient experienced cardiovascular collapse. His pacemaker failed, and he required insertion of a temporary transvenous pacemaker. At surgery, the defect was traced to failure of the pulse generator, a rare cause of pacemaker failure. Emergency department evaluation should include prompt and continuous ECG monitoring, an overpenetrated chest radiograph, and telemetry evaluation after discharge.

Carbon dioxide enrichment accelerates the decline in nutrient status and relative growth rate of Populus tremuloides Michx. seedlings

Changes in growth dynamics and mineral nutrient concentrations were measured in Populus tremuloides Michx., trembling aspen, grown for 100 days following germination in atmospheres containing 350 or 750 microl l(-1) CO(2). Seedlings were fertilized with nitrogen (N) at concentrations of 15.5 mM (high-N), 1.55 mM (medium-N), or 0.155 mM (low-N). Initially, relative growth rates were enhanced by CO(2) enrichment in each N regime, but the effects did not persist. In plants grown in high-N or medium-N, foliar concentrations of Ca and Mg decreased in response to CO(2) enrichment. During the 100-day study, whole-plant concentrations of N and P decreased in all treatments. The decreases in mineral nutrient concentrations over time were accelerated in CO(2)-enriched plants and accompanied the disappearance of the CO(2)-induced growth enhancement. It is concluded that the depression of relative growth rates often associated with long-term CO(2) enrichment of plants may result from decreases in plant nutrient status.

The regulation of biological products

The purpose of regulations for biological products is the same as that for any other medicinal or related products: the protection of recipients of the products. The entry into the age of molecular biology with its attendant development and manufacturing technology has placed new demands on regulatory agencies and related industry personnel. While the general goals of regulations remain the same, the scientific bases by which biological products must be reviewed and registered vary from those traditionally used for drugs or even older vaccines produced by conventional methods of growth, harvesting and purification. New regulations must be developed which take into account the new science involved in molecular biology and recombinant technology; new definitions must be provided and widely understood. The regulation of biologic products on an international basis is complicated by issues such as national interests superceding individual patient needs, bureaucracies being driven primarily by regulation and secondarily by science, industry expecting priority treatment for innovative products while having to absorb costs related to lost regulatory review time, and agencies or industry relying upon outdated regulations and/or archaic tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Norfloxacin versus trimethoprim-sulfamethoxazole in the treatment of urinary tract infections

In a controlled, randomized trial of 133 patients with proven urinary tract infections (UTIs), significantly more pathogens were found to be susceptible to norfloxacin than to trimethoprim-sulfamethoxazole (TMP-SMZ) (p less than 0.01). Among patients with pathogens susceptible to both drugs, more of those treated with norfloxacin were cured or improved (p = 0.06). When at least one patient variable, i.e., prior history of therapy, was corrected for, this difference became significant (p = 0.03). Norfloxacin eradicated 11 of 13 infections due to Pseudomonas aeruginosa and 6 of 7 due to enterococci. Five patients treated with norfloxacin and two treated with TMP-SMZ had relapses within 6 weeks. Significantly fewer adverse experiences occurred in patients receiving norfloxacin (p less than 0.01).

Imipenem-cilastatin in pediatric patients: an overview of safety and efficacy in studies conducted in the United States

Imipenem-cilastatin was evaluated for tolerability and efficacy in a multicenter open, noncomparative trial involving 178 infants and children with bacterial infections. Imipenemcilastatin was administered in total daily dosages of 100 mg/kg for patients up to 3 years of age and 60 mg/kg for those more than 3 years of age. Favorable clinical response was achieved in 98 of 100 patients judged evaluable for efficacy. Adverse effects were generally mild and reversible and included diarrhea alone or with vomiting (5.1%), irritation of intravenous infusion site (3.3%) and rash (2.2%). Changes in laboratory test values reported most frequently were thrombocytosis (8.9%), elevations in aspartate aminotransferase (7.9%) and alanine aminotransferase (5.6%) and eosinophilia (8.4%). This safety profile appears to be comparable to that of other beta-lactam antibiotics. Moreover imipenem-cilastatin was effective in infections caused by a broad spectrum of pathogens that include Haemophilus influenzae, Staphylococcus aureus, P. aeruginosa and anaerobes. These attributes suggest that imipenem-cilastatin should be safe and effective in selected pediatric patients.