Exercise following a sport induced concussion

OBJECTIVE

To determine if an athlete's capacity to perform exercise is impaired following concussion and whether this would be reflected by an altered heart rate response.

METHODS

Of the 14 concussed athletes, nine missed playing time as a direct result of their concussion and five did not. The concussed athletes performed an exercise protocol on a cycle ergometer within 72 hours of being asymptomatic at rest and a second test at 5 days following the previous assessment. Matched controls (n = 14) were tested using the same time line. The exercise protocol consisted of a 2 minute warm up, 10 minute, low-moderate intensity, steady state exercise session, and a high intensity interval protocol. The interval protocol consisted of a 40 second high intensity bout, followed by a 40 second rest period. This protocol continued until the participant had reached volitional fatigue.

RESULTS

The number of exercise bouts completed was not significantly different from their matched controls. However, concussed athletes who missed playing time had a significantly higher heart rate during the steady state exercise session. During this same period, they also exhibited a greater rise in heart rate over time.

CONCLUSION

These findings indicate that exercise capacity is unaffected in concussed athletes who are asymptomatic at rest. However, their heart rate response to submaximal exercise is increased.

Development and standardization of a rapid, PCR-based method for the detection of Wuchereria bancrofti in mosquitoes, for xenomonitoring the human prevalence of bancroftian filariasis

PCR has recently been studied as a promising tool for monitoring the progress of efforts to eliminate lymphatic filariasis. PCR can be used to test concurrently at least 30 pools, with as many as 40 mosquitoes in each pool, for the presence of filarial larvae. The SspI PCR assay for the detection of Wuchereria bancrofti DNA in pools of mosquitoes has been used since 1994 in a variety of laboratories worldwide. During that time, the original assay has been modified in these different laboratories and no standardized assay currently exists. In an effort to standardize and improve the assay, a meeting was held on 15-16 November 2001, at Emory University in Atlanta, with representatives from most of the laboratories currently using the assay. The first round of testing was designed to test the four most promising methods for DNA extraction from pools of mosquitoes. Two of the four methods stood out as clearly the best and these will be now optimised and evaluated in two further rounds of testing.

Concussions in hockey: there is cause for concern

PURPOSE

The purpose of the study was to document various aspects of concussion in Canadian Amateur hockey including demographics, causes, treatment, and prevention in order to guide future recommendations on how to reduce injury.

METHODS

A detailed prospective and retrospective concussion history was obtained from British Columbia Junior Hockey League players over the course of two seasons (1998-2000).

RESULTS

Higher rates of concussions occur in games versus practice, and there was an overrepresentation of forwards injured versus defensemen or goaltenders. There was between 4.63 and 5.95 concussions per 1000 player/game hours with the average age of the first hockey-related concussion in the 15th year. The greatest cause of concussion was contact with the ice and/or the boards. Fighting was not a major cause of concussion, although other illegal actions such as elbowing were.

CONCLUSIONS

The primary recommendation to reduce the number and severity of concussions is to eliminate plays where there is a demonstrable intent to injure another player. Concussions in hockey are of considerable concern; however, there is now encouraging information with respect to the treatment of these injuries.

Bacterial keratitis after [correction of following] laser in situ keratomileusis

PURPOSE

The development of bacterial keratitis after laser in situ keratomileusis (LASIK) has been described in only a few isolated cases. We report the development of bacterial keratitis as a postoperative complication of LASIK in three subjects.

DESIGN

A retrospective interventional small case series.

PARTICIPANTS

Three patients who underwent LASIK for correction of myopia during July and August 1998 and had bacterial keratitis develop after surgery.

METHODS

Bacterial keratitis was encountered in the operated eyes between 1 and 22 days after surgery. Topical antibiotic therapy was administered. In one eye, which had significant opacification and irregularity of the flap was developed, lamellar keratoplasty was performed.

MAIN OUTCOME MEASURES

Postoperative inflammation was followed clinically and photographically until it resolved. Visual acuity was measured at intervals throughout the follow-up period.

RESULTS

Keratitis resolved within 3 to 16 days of starting antibiotic therapy. The final best-corrected visual acuities were 20/30, 20/15, and 20/25.

CONCLUSIONS

Although infectious keratitis after LASIK is an infrequently reported event, it should be discussed preoperatively with patients as a possible complication.

Electrophysiological evidence for the cumulative effects of concussion

PURPOSE

A study was initiated with the intent of demonstrating the cumulative effects of concussion in junior hockey players using visual event-related potentials and post-concussion syndrome (PCS) self-reports.

METHODS

Players were assessed at the beginning of the season (pre-injury) and at various times post-injury.

RESULTS

The results suggest that players with three or more concussions differed significantly on the several cognitive PCS symptoms as well as for the latency of the P3 response compared to those with no concussion history.

DISCUSSION

Event-related potentials are useful indices of the cumulative damage that can occur following multiple concussions. These measures correlate significantly with cognitive self-reports of PCS symptoms.

CONCLUSIONS

This pattern of results is consistent with the position that each concussion potentially causes brain damage. Cumulative damage can be detected using electrophysiological measures of brain function.

A distinctive clade B HIV type 1 is heterosexually transmitted in Trinidad and Tobago

HIV-1 transmission worldwide is predominantly associated with heterosexual activity, and non-clade B viruses account for the most spread. The HIV-1 epidemic in Trinidad/Tobago and the Caribbean shares many features with such heterosexual epidemics, including a prominent role for coincident sexually transmitted diseases. This study evaluates the molecular epidemiology of HIV-1 in Trinidad/Tobago during a period when abrupt transition from homosexual to heterosexual transmission occurred in the absence of injecting drug use, concomitant with a rapid rise in HIV-1 prevalence in the heterosexual population. Of 31 viral isolates studied during 1987-1995, all cluster with subtype B reference strains. In the analysis of full env genes from 22 early seroconverters, the Trinidad isolates constitute a significant subcluster within the B subtype. The Trinidad V3 consensus sequence differs by a single amino acid from the prototype B V3 consensus and demonstrates stability over the decade of this study. In the majority of isolates, the V3 loop of env contains a signature threonine deletion that marks the lineage of the Trinidad HIV-1 clade B epidemic from pre-1984. No phenotypic features, including syncitium induction, neutralization profiles, and chemokine receptor usage, distinguish this virus population from other subtype B viruses. Thus, although the subtype B HIV-1 viruses being transmitted in Trinidad are genetically distinguishable from other subtype B viruses, this is probably the result of a strong founder effect in a geographically circumscribed population rather than genetic selection for heterosexual transmission. These results demonstrate that canonical clade B HIV-1 can generate a typical heterosexual epidemic.

Naturally acquired anti-alpha Gal antibodies in a murine allograft model similar to delayed xenograft rejection

Antibodies directed against galactose-alpha1,3-galactose (alphaGal) are believed to play an important role in the pathogenesis of delayed xenograft rejection (DXR). This study was designed to determine whether alpha1,3-galactosyltransferase-deficient (Gal KO) mice can naturally acquire a sufficient anti-alphaGal titre to cause the delayed type rejection of alphaGal-expressing hearts. Gal KO mice of various ages were assessed for anti-alphaGal antibody levels. alphaGal-expressing hearts were transplanted heterotopically into these mice and monitored daily. Rejecting and surviving hearts were evaluated histologically. In Gal KO mice greater than 6-month-old, 64% had an anti-alphaGal antibody titre above the background level. When wild-type alphaGal-expressing hearts were transplanted into this group, 45% of grafts rejected within 5 to 13 days. Histological examination of the rejected hearts displayed marked tissue damage and an inflammatory infiltrate of predominantly macrophage/monocytes. Surviving grafts showed preserved morphology. Like humans, Gal KO mice naturally develop anti-alphaGal antibodies with age. The titre in these mice was sufficient to cause a "delayed-type" rejection of a significant proportion of alphaGal-expressing cardiac grafts. This model thus provides an opportunity to investigate the role of naturally acquired anti-alphaGal antibodies in the pathogenesis of DXR.

Early-invasive or early-conservative management of patients with unstable angina or non-Q-wave myocardial infarction

The optimal therapy for non-ST-segment-elevation acute coronary syndromes is the subject of considerable debate: is early catheterization and revascularization (early-invasive strategy) or continued medical therapy unless symptoms are refractory (early-conservative strategy) best? Although several clinical trials have sought to answer this question, the methodologies they employed have been widely criticized, and no consensus has been reached. The new antiplatelet therapies have proved beneficial for primary medical management and as adjuncts to percutaneous interventions. It is not yet clear, however, whether use of these therapies will preferentially benefit one of the treatment strategies.

Age of onset in chronic major depression: relation to demographic and clinical variables, family history, and treatment response

BACKGROUND

The clinical and etiological significance of the early-late onset distinction in chronic major depressive disorder was explored.

METHOD

Subjects were 289 outpatients with DSM-III-R chronic major depression drawn from a multi-site study comparing the efficacy of sertraline and imipramine in the acute and long-term treatment of chronic depression. Patients received comprehensive evaluations using semi-structured interviews and rating scales.

RESULTS

Early-onset chronic major depression was associated with a longer index major depressive episode and higher rates of recurrent major depressive episodes, comorbid personality disorders, lifetime substance use disorders, depressive personality traits, and a history of psychiatric hospitalization. In addition, more early-onset patients tended to have a family history of mood disorders. The early-late onset distinction was not associated with differences in symptom severity, functional impairment, or treatment response.

LIMITATIONS

Family members were not interviewed directly; there were a large number of statistical comparisons; and interrater reliability of the assessments was not evaluated.

CONCLUSIONS

Early-onset chronic major depression has a more malignant course and is associated with greater comorbidity than late-onset chronic major depression.

Meniscus regeneration in a rabbit partial meniscectomy model

Meniscectomy is known to be associated with osteoarthrosis of the knee. The purpose of this study was to compare the natural and augmented repair of menisci in the knees of New Zealand White rabbits. To create a partial defect in the medial meniscus, we used an experimental model that has been well characterized and extensively used in the study of osteoarthrosis and articular cartilage repair. The defect was left untreated or treated with one of the following: a periosteal autograft, a type I collagen sponge, or the same sponge loaded with autologous, bone marrow-derived, cultured mesenchymal stem cells. The natural repair was always incomplete and degenerative changes within these joints were progressive. The periosteal autograft underwent differentiation into a bone and hyaline cartilage composite that was ineffectual as a meniscus and accelerated the degenerative changes in those joints when compared to natural repair controls. There was evidence of a consistent sequence of events in the transformation of the periosteal grafts to a core of cartilage that underwent endochondral ossification. In the last two groups, the collagen sponge functioned as a scaffold that resulted in more abundant repair tissue. The collagen sponge alone supported a largely fibrous repair process. The cultured mesenchymal stem cells were observed to augment the repair process in some specimens to include fibrocartilage histologically similar to normal meniscus. Degenerative changes were present in both of these groups, which indicates that the biomechanical function of the meniscus was not restored, or an irreversible osteoarthrosis cascade was initiated during the repair period. Based on these preliminary studies, further investigation of cell-based meniscus regeneration appears to be warranted.

Determination of the potency of remifentanil compared with alfentanil using ventilatory depression as the measure of opioid effect

BACKGROUND

Remifentanil is a new opioid with properties similar to other mu-specific agonists. To establish its pharmacologic profile relative to other known opioids, it is important to determine its potency. This study investigated the relative potency of remifentanil compared with alfentanil.

METHODS

Thirty young healthy males were administered double-blind remifentanil or alfentanil intravenously for 180 min using a computer-assisted continuous infusion device. Depression of ventilation was assessed by the minute ventilatory response to 7.5% CO2 administered via a "bag in the box" system. The target concentration of the study drug was adjusted to obtain 40-70% depression of baseline minute ventilation. Multiple blood samples were obtained during and following the infusion. The concentration-effect relationship of each drug was modeled, and the concentration needed to provide a 50% depression of ventilation (EC50) was determined.

RESULTS

Only 11 subjects in each drug group completed the study; however, there were sufficient data in 28 volunteers to model their EC50 values. The EC50 (mean and 95% confidence interval) for depression of minute ventilation with remifentanil was 1.17 (0.85-1.49) ng/ml and the EC50 for alfentanil was 49.4 (32.4-66.5) ng/ml.

CONCLUSION

Based on depression of the minute ventilatory response to 7.5% CO2, remifentanil is approximately 40 (26-65) times more potent than alfentanil when remifentanil and alfentanil whole-blood concentrations are compared. As alfentanil is usually measured as a plasma concentration, remifentanil is approximately 70 (41-104) times more potent than alfentanil when remifentanil whole-blood concentration is compared with alfentanil plasma concentration. This information should be used when performing comparative studies between remifentanil and other opioids.

Early- versus late-onset dythymic disorder: comparison in out-patients with superimposed major depressive episodes

BACKGROUND

This study examined the validity of the early-late onset subtyping distinction in dysthymic disorder.

METHODS

Participants were 340 out-patients meeting DSM-III-R criteria for dysthymia and a concurrent major depressive episode (MDE). The sample was drawn from a 12-site double-blind randomized parallel group trial comparing the efficacy of sertraline and imipramine in the treatment of chronic depression. All patients received comprehensive evaluations using semi-structured interviews and rating scales.

RESULTS

73% of the sample met criteria for the early-onset, and 27% for the late-onset, subtype. The early-onset patients had a significantly longer index MDE, significantly higher rates of personality disorders and lifetime substance use disorders, and a significantly greater proportion had a family history of mood disorder. The subgroups did not differ in symptom severity or functional impairment at baseline, nor in response to a 12-week trial of antidepressants.

LIMITATIONS

Further work is needed to extend these findings to dysthymic disorder without superimposed MDEs.

CONCLUSIONS

These results support the distinction between early-onset and late-onset dysthymic disorder.

Antigen-specific antibody responses in lupus patients following immunization

OBJECTIVE

To determine the safety and efficacy of 3 clinically relevant vaccines in patients with systemic lupus erythematosus (SLE).

METHODS

We studied 73 consecutive SLE patients immunized with pneumococcal, tetanus toxoid (TT), and Haemophilus influenzae type B (HIB) vaccines. Patients were evaluated preimmunization and 12 weeks postimmunization for disease activity and immunization side effects.

RESULTS

Eighty-four percent of the SLE patients developed a 4-fold titer increase in response to at least 1 vaccine, with 51% developing a 2-fold titer increase with all 3 vaccines. The majority of SLE patients developed protective levels of antibody to TT (90%) and HIB (88%). Although protective antibody levels could not be determined for pneumococcus, almost half of the patients (47%) developed a 4-fold antibody response. There was a trend toward a lower antibody response in patients with active disease treated with immunosuppressive therapy. Overall lupus disease activity was unaffected by immunization.

CONCLUSION

Immunization is safe in SLE patients, with the overwhelming majority developing protective antibody levels. Therefore, SLE patients should receive immunizations according to the recommendations of the Centers for Disease Control and Prevention and the Immunization Practices Advisory Committee.

Breast enlargement during chronic antidepressant therapy

Recent reports of mammoplasia during selective serotonin re-uptake inhibitor (SSRI) therapy suggested that this side effect may be more common than previously reported. We examined 59 women receiving > or = 2 months treatment with an SSRI or venlafaxine for changes in breast size in relation to menopausal status, weight gain and duration of drug therapy. Serum prolactin, estradiol and beta-hCG were also measured before and during treatment in a subgroup of patients. Twenty-three out of 59 patients (39%) reported some degree of mammoplasia. Significantly more SSRI vs. venlafaxine patients reported mammoplasia (p < 0.01). Eighty-four percent with mammoplasia had weight gain vs. 30% without mammoplasia (p < 0.001). The rate of mammoplasia was unrelated to age, menopausal status or duration of treatment. Serum prolactin increased during treatment in the paroxetine subgroup (p < 0.03). In conclusion, antidepressant-induced mammoplasia may be more common than previously expected.

Application of the Critical Pathway and Integrated Case Teaching Method to Nursing Orientation

BACKGROUND

Nursing staff development programs must be responsive to current changes in healthcare. New nursing staff must be prepared to manage continuous change and to function competently in clinical practice.

METHOD

The orientation pathway, based on a case management model, is used as a structure for the orientation phase of staff development. The integrated case is incorporated as a teaching strategy in orientation. The integrated case method is based on discussion and analysis of patient situations with emphasis on role modeling and integration of theory and skill.

RESULTS

The orientation pathway and integrated case teaching method provide a useful framework for orientation of new staff. Educators, preceptors and orientees find the structure provided by the orientation pathway very useful.

CONCLUSION

Orientation that is developed, implemented and evaluated based on a case management model with the use of an orientation pathway and incorporation of an integrated case teaching method provides a standardized structure for orientation of new staff. This approach is designed for the adult learner, promotes conceptual reasoning, and encourages the social and contextual basis for continued learning.

Transfection with human thioredoxin increases cell proliferation and a dominant-negative mutant thioredoxin reverses the transformed phenotype of human breast cancer cells

Thioredoxin, a redox protein with growth factor activity that modulates the activity of several proteins important for cell growth, has been reported to be overexpressed in a number of human primary cancers. In the present study, the effects of stably transfecting mouse NIH 3T3 cells and MCF-7 human breast cancer cells with cDNA for wild-type human thioredoxin or a redox-inactive mutant thioredoxin, Cys32-->Ser32/Cys35-->Ser35 (C32S/C35S), on cell proliferation and transformed phenotype have been investigated. NIH 3T3 cells transfected with thioredoxin achieved increased saturation densities compared with vector alone-transfected cells, but were not transformed as assessed by tumor formation in immunodeficient mice. Thioredoxin-transfected MCF-7 cells showed unaltered monolayer growth on plastic surfaces compared with vector alone-transfected cells, but exhibited severalfold increased colony formation in soft agarose. Stable transfection of NIH 3T3 and MCF-7 cells with C32S/C35S resulted in inhibition of monolayer growth on plastic surfaces, and up to 73% inhibition of colony formation by MCF-7 cells in soft agarose. When inoculated into immunodeficient mice, thioredoxin-transfected MCF-7 cells formed tumors, although with a 38-57% growth rate compared with vector alone-transfected cells, whereas tumor formation by C32S/C35S-transfected MCF-7 cells was almost completely inhibited. The results of the study suggest that thioredoxin plays an important role in the growth and transformed phenotype of some human cancers. The inhibition of tumor cell growth by the dominant-negative redox-inactive mutant thioredoxin suggests that thioredoxin could be a novel target for the development of drugs to treat human cancer.