Human immunodeficiency virus replication in AIDS patients with Mycobacterium avium complex bacteremia: a case control study. California Collaborative Treatment Group

The development of opportunistic infections and the administration of vaccines have been associated with transient increases of human immunodeficiency virus (HIV) RNA plasma levels in HIV-infected patients. To determine the relationship between Mycobacterium avium complex (MAC) bacteremia and HIV RNA levels, HIV RNA levels in patients who developed MAC bacteremia (cases) were compared with levels in patients who remained free of MAC disease (controls). Cases and controls were matched for CD4 cell count, prophylaxis against MAC disease, antiretroviral therapy, and duration of follow-up. Mean baseline HIV RNA levels were 4.8 log10 copies/mL in cases and 4.6 log10 copies/mL in controls (P = 0.22). HIV RNA levels increased by a median of 0.4 log in cases but not controls at the time of MAC bacteremia (P = 0.01). In AIDS patients, the onset of MAC bacteremia is associated with a modest but significant increase in serum HIV RNA levels. Increased HIV replication may contribute to the higher mortality associated with MAC bacteremia.     

A longitudinal cephalometric study of the soft tissue profile of short- and long-face syndromes from 7 to 17 years

The longitudinal growth and development of the soft tissue drape for boys and girls with long and short vertical patterns was examined from age 7 to 17 years. The sample was taken from the Denver Growth Study and consisted of 32 subjects who were selected on the basis of their percentage of lower anterior vertical face height. All subjects were of northern European ancestry, and none had undergone orthodontic treatment. The sexual dimorphism was evident as anticipated for several soft tissue measurements. The boys showed continued growth through age 16 years in contrast to the girls who attained the adult size of the soft tissue integument around 14 years. A significant difference between vertical facial patterns was reported for all soft tissue variables with the exception of the soft tissue thickness at A point and the upper lip height. The boys and girls with long vertical patterns exhibited a thicker and longer soft tissue drape for the most variables when compared with those with short facial patterns. These soft tissue differences are believed to be compensatory mechanisms in long-face subjects, which may attempt to mask the vertical dysplasia, thereby producing a more normal facial profile. Individual growth assessments revealed that the perioral soft tissues follow a pattern similar to that of the mean group patterns. The subjects with long vertical facial patterns experienced their pubertal growth spurt earlier than the short-face subjects. This may have clinical implications in the timing of orthodontic intervention and treatment.     

Shelf life and in vivo duration. Impacts on performance of tibial bearings

Polyethylene has been used for more than 30 years as an orthopaedic bearing material; however, recently concern has been focused on the early failure of some polyethylene bearings. The damage seen in some bearings has been linked to gamma radiation sterilization performed in an air environment. Gamma sterilization in air has been documented to cause an increase in oxidation and degradation of mechanical properties that continue with time. However, not all retrieved bearings that are gamma sterilized in air exhibit the elevated oxidation and mechanical property degradation that lead to early component failure. Bearings that are gamma sterilized in air oxidize while sitting in inventory before implantation. Shelf oxidation rate was estimated based on analysis of a series of never implanted tibial bearings. This shelf oxidation rate allowed estimation of in vivo oxidation for retrieved tibial bearings of known sterilization date. Bearings with less than 1 year of shelf life after gamma sterilization in air had lower in vivo oxidation and better in vivo performance than did those with longer shelf life before implantation. Shelf time before implantation appears to be a significant factor in the success or failure of bearings that are gamma sterilized in air.     

A kinetic study of NOx reduction over Pt/SiO2 model catalysts with hydrogen as the reducing agent

Flow reactor experiments and kinetic modeling have been performed in order to study the mechanism and kinetics of NO_x reduction over Pt/SiO₂ catalysts with hydrogen as the reducing agent. The experimental results from NO oxidation and reduction cycles showed that N₂O and NH₃ are formed when NO_x is reduced with H₂. The NH₃ formation depends on the H₂ concentration and the selectivity to NH₃ and N₂O is temperature dependent. A previous model has been used to simulate NO oxidation and a mechanism for NO_x reduction is proposed, which describes the formation/consumption of N₂, H₂O, NO, NO₂, N₂O, NH₃, O₂ and H₂. A good agreement was found between the performed experiments and the model.     

Successful long-term kidney-pancreas transplants in diabetic patients with high C-peptide levels

Health Canada and the Canadian-Italian Physicians Association recently spent $20,000 to send 4 Canadian cancer specialists to Italy to check out the "miracle" anticancer cocktail prepared by an Italian physician. Most doctors remain decidedly sceptical about this latest "cure," but Charlotte Gray says their suspicions count for little when an issue like this captures the imagination of the public and their politicians.     

Restricted T cell receptor repertoire for acetylcholine receptor in murine myasthenia gravis

Immunization of C57BL/6 mice with AChR provokes symptoms similar to those seen in the disease myasthenia gravis. To elucidate the structural requirements for T cell recognition of AChR and to identify TcR features which might provide targets for immunotherapy, a panel of T cell hybridomas was generated after immunization of mice with the immunodominant peptide of the AChR alpha chain. The TcR genes expressed by these hybridomas were sequenced. TcR-V beta 6 was preferentially employed, but other V beta genes were also observed. A conserved acidic residue was present in all CDR3 regions, regardless of the V beta. The TcR-V alpha repertoire was somewhat skewed with three V alpha families accounting for 82% of the sequences. The utilization of multiple T cell receptor V beta genes may contribute to the inability to inhibit EAMG by elimination of V beta 6+ T cells.     

A survey of New Zealand psychiatrists' clinical experience with the Mental Health (Compulsory Assessment and Treatment) Act of 1992

AIMS: This study examines the clinical experience of New Zealand psychiatrists with the Mental Health (and Compulsory Assessment and Treatment) Act of 1992. METHODS: A survey was distributed to all psychiatric specialists residing in New Zealand who were registered with the Medical Council of New Zealand (n = 232). The survey examined the extent of practitioners' use of the Mental Health Act, perceived strengths and weaknesses of the Mental Health Act, and experiences with the family court system. RESULTS: Psychiatrists estimated that almost half (46.4%) of patients retained under the Mental Health Act were released within 3 weeks. Inpatient consultants reported dedicating 18.6% of their working time to Mental Health Act related activities. A majority of respondents indicated that: the Mental Health Act requires major revision (55.6%), the Mental Health Act results in the inappropriate release of some psychiatric patients into the community (70.9%), and that compulsory treatment orders are a useful tool for promoting community treatment of the mentally ill (69.2%). While a majority (81.5%) indicate that individual judges are consistent in their interpretation of the Mental Health Act across cases, only 26.5% of respondents agree that the law is interpreted uniformly by different judges. CONCLUSIONS: The Mental Health Act is perceived as time-consuming and cumbersome to administer. However, compulsory treatment orders do facilitate community treatment, an explicit goal of the Mental Health Act. Proposed areas for refinement of the Mental Health Act are discussed. Further examination of the interface between psychiatrists and the family court system would be useful.     

Neuropsychological test performance in patients with dominantly inherited spinocerebellar ataxia: relationship to ataxia severity

To determine whether the cognitive status of patients with dominantly inherited spinocerebellar ataxia (DSCA) might be related to neurologic severity, we administered a comprehensive neuropsychological test battery to 43 patients with DSCA, ranging in ataxia severity from mild to end-stage. As compared with the controls, the mildly ataxic patients scored normally or close to normal as a group on all of the neuropsychological tests. In contrast, approximately one-half of the moderately and all of the severely ataxic patients showed poor performance, independent of age, Hamilton Rating Scale for Depression score, or education, on the Wisconsin Card Sorting Test, suggesting impaired executive system function. In addition, a subgroup of these patients had a neuropsychological profile suggestive of mild generalized cognitive impairment. We conclude that DSCA is not a homogeneous group of disorders with respect to cognitive status and that the neurologic severity of the disorder is a major factor. Impaired executive system function could be explained by damage to olivopontocerebellar system control over cerebral cortical function or to damage to other neuronal systems (especially cholinergic) that degenerate in parallel with the olivopontocerebellar system.     

Overview of the Fundamental Reactions and Degradation Mechanisms of NOx Storage/Reduction Catalysts

Over the last several years, nitrogen oxide(s) (NOx) storage/reduction (NSR) catalysts, also referred to as NOx adsorbers or lean NOx traps, have been developed as an aftertreatment technology to reduce NOx emissions from lean-burn power sources. NSR operation is cyclic: during the lean part of the cycle, NOx are trapped on the catalyst; intermittent rich excursions are used to reduce the NOx to N₂ and restore the original catalyst surface; and lean operation then resumes. This review will describe the work carried out in characterizing, developing, and understanding this catalyst technology for application in mobile exhaust-gas aftertreatment. The discussion will first encompass the reaction process fundamentals, which include five general steps involved in NOx reduction to N₂ on NSR catalysts; NO oxidation, NO₂ and NO sorption leading to nitrite and nitrate species, reductant evolution, NOx release, and finally NOx reduction to N₂. Major unresolved issues and questions are listed at the end of each of the reaction process fundamental sections. Degradation mechanisms and their effects on NSR catalyst performance are also described in relation to these generalized reactions. Since at this stage it does not appear possible to arrive at a complete and consistent mechanistic model describing the broad, existing experimental phenomenology for these processes, this review is primarily focused on summarizing and evaluating literature data and reconciling the many differences presented.