Effects of body temperature during exercise training on myocardial adaptations

This study determined the role of body temperature during chronic exercise on myocardial stress proteins and antioxidant enzymes as well as functional recovery after an ischemic insult. Male Sprague-Dawley rats were exercised for 3, 6, or 9 wk in a 23 degrees C room (3WK, 6WK, and 9WK, respectively) or in a 4-8 degrees C environment with wetted fur (3WKC, 6WKC, and 9WKC, respectively). The colder room prevented elevations in core temperature. During weeks 3-9 the animals ran 5 days/wk up a 6% grade at 20 m/min for 60 min. Myocardial heat shock protein 70 (HSP 70) increased 12.3-fold (P < 0.05) in 9WK versus sedentary (SED) rats but was unchanged in the cold-room runners. Compared with SED rats, alphaB-crystallin was 90% higher in 9WKC animals, HSP 90 was 50% higher in 3WKC and 6WKC animals, and catalase was 23% higher in 3WK animals (P < 0.05 for all). Cytosolic superoxide dismutase increased and mitochondrial SOD decreased (P < 0.05) in 3WK and 6WK rats compared with 3WKC and 6WKC rats. Antioxidant enzymes returned to SED values in all runners by 9 wk. No differences were observed among any of the groups for glucose-regulated protein 75, heme oxygenase-1, or glutathione peroxidase. Mechanical recovery of isolated working hearts after 22.5 min of global ischemia was enhanced in 9WK (P < 0.05) but not in 9WKC rats. We conclude that exercise training results in dynamic changes in cardioprotective proteins over time which are influenced by core temperature. In addition, cardioprotection resulting from chronic exercise appears to be due to increased HSP 70.

The influence of NMDA receptor-mediated processes on breathing pattern in ground squirrels

The effects of blockade of N-methyl-D-aspartate (NMDA) type glutamate receptors by a non-competitive antagonist (MK-801) on cortical arousal, breathing pattern and ventilatory responses to hypoxia (10% O2 in N2) and hypercapnia (5% CO2 in air) were assessed in anesthetized (urethane) and unanesthetized golden-mantled ground squirrels (Spermophilus lateralis). Intra-cerebroventricular administration of MK-801 did not alter ventilation during wakefulness, although it did alter the pattern (breathing frequency and tidal volume components) of the hypercapnic ventilatory response, and suppressed the ventilatory response to hypoxia. Animals did not sleep following treatment with MK-801, and intravenous administration of MK-801 prevented expression of the sleep-like state normally observed in anesthetized animals. In anesthetized animals MK-801 elevated breathing frequency to levels observed without anesthesia, and suppressed the hypoxic ventilatory response. These data suggest that NMDA-type glutamatergic receptor-mediated processes influence cortical arousal and facilitate depression of breathing frequency during anesthesia and the hypoxic ventilatory response. Such processes are not essential for the hypercapnic ventilatory response.

Vagal feedback is essential for breathing in unanesthetized ground squirrels

The roles of vagal afferent feedback in terminating inspiration and modulating breathing pattern and ventilatory responses to hypoxia and hypercapnia were assessed in the golden-mantled ground squirrel, Spermophilus lateralis, during wakefulness and urethane anesthesia. Hypoxia increased ventilation primarily through increases in breathing frequency (f(R)) while hypercapnia increased ventilation primarily through increases in tidal volume (V(T)) in both anesthetized and unanesthetized animals. Vagotomy resulted in an increase in tidal volume, a decrease in breathing frequency and ventilation, and depressed ventilatory responses to both hypoxia and hypercapnia in anesthetized animals. In unanesthetized animals vagotomy produced a transient 'gasp-like' breathing pattern that rapidly progressed to a non-obstructive central apnea. These data indicate that vagal feedback shapes ventilation on a breath-by-breath basis during anesthesia and is essential for ventilation in unanesthetized animals. The mechanisms that transform the influences of vagal input on breathing between anesthetized and unanesthetized states remain unclear. Changes in breathing pattern induced by the removal of vagal feedback compromise chemoreflexes.

Evolution of air-breathing and central CO(2)/H(+) respiratory chemosensitivity: new insights from an old fish?

While little is known of the origin of air-breathing in vertebrates, primitive air breathers can be found among extant lobe-finned (Sarcopterygii) and ray-finned (Actinopterygii) fish. The descendents of Sarcopterygii, the tetrapods, generate lung ventilation using a central pattern generator, the activity of which is modulated by central and peripheral CO(2)/H(+) chemoreception. Air-breathing in Actinopterygii, in contrast, has been considered a ‘reflexive’ behaviour with little evidence for central CO(2)/H(+) respiratory chemoreceptors. Here, we describe experiments using an in vitro brainstem preparation of a primitive air-breathing actinopterygian, the longnose gar Lepisosteus osseus. Our data suggest (i) that gill and air-breathing motor patterns can be produced autonomously by the isolated brainstem, and (ii) that the frequency of the air-breathing motor pattern is increased by hypercarbia. These results are the first evidence consistent with the presence of an air-breathing central pattern generator with central CO(2)/H(+) respiratory chemosensitivity in any primitive actinopterygian fish. We speculate that the origin of the central neuronal controller for air-breathing preceded the divergence of the sarcopterygian and actinopterygian lineages and dates back to a common air-breathing ancestor.

Evaluation of the cervical spine in the polytrauma patient

STUDY DESIGN

Two-part study. Part One: the analysis of surveys distributed to members of the Orthopaedic Trauma Association (OTA) and 1000 surgeon members of NASS. Part Two: a prospective clinical study evaluating a new algorithm to evaluate the cervical spine in polytrauma patients.

OBJECTIVES

To determine if there is a consensus of the optimal method for "clearing the cervical spine"; to assess the safety and efficacy of a newly proposed algorithm.

SUMMARY OF BACKGROUND DATA

There is no uniformly accepted algorithm for "clearing the cervical spine" in the polytrauma patient or those patients with altered mental status secondary to the influence of alcohol, drugs or a closed head injury.

METHODS

All members of the OTA and 1000 surgeon members of NASS were sent questionnaires to assess their methods of "clearing the cervical spine" in the polytrauma patient. Their answers were collated, analyzed and compared to standard ATLS protocol guidelines. A new protocol, which includes a surgeon, controlled stretch test and flouroscopically visualized flexion-extension views, was initiated and evaluated for safety and efficacy.

RESULTS

SURVEY

Fifty-five percent of the members of the OTA and 31% of the NASS surgeons responded to the questionnaire. Among the responses from the NASS members, the ratio of orthopaedic spine surgeons to neurosurgeons accurately parallels the society's membership (77% ortho, 23% neuro). Sixty-nine of the OTA and 54% of the NASS responders replied that they followed ATLS guidelines. Analysis of their responses showed only 40% compliance. Eighty-one percent of the OTA respondents utilize the standard three view cervical spine trauma series, only 31% of the NASS members adhere to this guideline. Nearly 90% of all respondents identified the presence of neck pain or retropharygeal soft tissue swelling as an indicator to expand their initial radiographic evaluation. There was no consensus as to management of the polytrauma patient with a closed head injury. Eighty-two percent of all respondents has seen or treated a purely ligamentous injury of the c-spine. SPECTIVE STUDY: Prospective clinical protocol. 35-month period: enrolled 153 patients, 12,000 patients seen in trauma unit. Completed data 149/153. 8/153 unable to be cleared due to poor visualization of cervical-thoracic junction. 3/153 positive findings identified during fluoro examination. All three instability patterns verified in surgery (true positives). No untoward events to date.

CONCLUSIONS

A standardized protocol to safely and effectively clear the cervical spine has yet to be established. Preliminary results of a new protocol to safely evaluate the cervical spine in the polytrauma patient are promising.

Phase II trial of pyrazoloacridine in children with solid tumors: a Pediatric Oncology Group phase II study

PURPOSE

Pyrazoloacridine (PZA), a rationally synthesized deoxyribonucleic acid (DNA) binding agent that preferentially inhibits ribonucleic acid rather than DNA synthesis, is active against hypoxic and noncycling tumor cells and has greater in vitro activity against a broad range of human solid tumor lines than against the L1210 murine leukemia line. The Pediatric Oncology Group conducted a phase II study to determine the activity of PZA administered as a 3-hour infusion.

PATIENTS AND METHODS

The activity of PZA was evaluated in patients with a variety of childhood solid tumors including rhabdomyosarcoma, Ewing sarcoma/peripheral neuroectodermal tumor, neuroblastoma, osteogenic sarcoma, Wilms tumor, or other solid tumors (excluding brain tumors). In addition to a standard three-stage design to test the drug's activity in each tumor type, a global stopping rule was used such that if no complete or partial responses (CR or PR) occurred in the first 35 patients (pooled across all strata except "other"), the study would be closed.

RESULTS

A total of 47 patients were entered into the study. Myelosuppression was the primary toxicity. Severe nonhematologic toxicity was uncommon. Only one patient exhibited grade 3 neurologic toxicity (anxiety). No CRs or PRs were observed.

CONCLUSION

Use of the global stopping criterion permitted early identification of lack of activity of PZA against childhood solid tumors.

Bradykinin activates the Janus-activated kinase/signal transducers and activators of transcription (JAK/STAT) pathway in vascular endothelial cells: localization of JAK/STAT signalling proteins in plasmalemmal caveolae

Bradykinin (BK) is an important physiological regulator of endothelial cell function. In the present study, we have examined the role of the Janus-activated kinase (JAK)/signal transducers and activators of transcription (STAT) pathway in endothelial signal transduction through the BK B2 receptor (B2R). In cultured bovine aortic endothelial cells (BAECs), BK activates Tyk2 of the JAK family of tyrosine kinases. Activation results in the tyrosine phosphorylation and subsequent nuclear translocation of STAT3. BK also activates the mitogen-activated p44 and p42 protein kinases, resulting in STAT3 serine phosphorylation. Furthermore, Tyk2 and STAT3 form a complex with the B2R in response to BK stimulation. Under basal conditions, Tyk2, STAT3 and the B2R are localized either partially or entirely in endothelial plasmalemmal caveolae. Following BK stimulation of BAECs, however, the B2R and STAT3 are translocated out of caveolae. Taken together, these data suggest that BK activates the JAK/STAT pathway in endothelial cells and that JAK/STAT signalling proteins are localized in endothelial caveolae. Moreover, caveolar localization of the B2R and STAT3 appears to be regulated in an agonist-dependent manner.

Treatment of children with early pre-B and pre-B acute lymphocytic leukemia with antimetabolite-based intensification regimens: a Pediatric Oncology Group Study

Between May 1987 and January 1991, 1354 patients, 1-21 years old, with standard or poor prognosis B-lineage acute lymphocytic leukemia were treated on the Pediatric Oncology Group Study 8602. One thousand three hundred and twenty-three patients entered remission and 1051 patients were randomized on day 43 to an intensification regimen containing L-asparaginase and intermediate-dose methotrexate (regimen B) or cytarabine and intermediate dose methotrexate (regimen C). After completion of intensification at week 25, all patients received the same maintenance therapy until 3 years from diagnosis. Overall 5-year continuous complete remission (CCR) for regimen B was 72+/-2% (s.e.) and for regimen C, 73+/-2% (P = 0.72 by log-rank analysis). Significant differences between treatments for CCR, testicular, CNS relapses overall or with regard to phenotype (pre-B vs early pre-B), gender, or race were not detected. During intensification, regimen C had significantly more bacterial infections (P = 0.05) and days spent in the hospital (P < 0.001) compared with regimen B, while regimen B had significantly more allergic reactions (P < 0.0001). No significant differences in CCR were noted between patients with pre-B and early pre-B ALL (P = 0.22 stratified by risk group and treatment). This study was unable to detect statistical difference between asparaginase (regimen B) and cytarabine (regimen C) during the intensification phase of therapy in children with B-lineage acute lymphocytic leukemia.

Role of heat shock protein 90 in bradykinin-stimulated endothelial nitric oxide release

Previously we described ENAP-1, a 90-kDa protein that is tyrosine-phosphorylated in endothelial cells in response to bradykinin (BK) stimulation and is associated with endothelial nitric oxide synthase (eNOS). Subsequently, other investigators demonstrated that eNOS interacts with heat shock protein 90 (Hsp90) following stimulation of endothelial cells with vascular endothelial growth factor (VEGF), histamine, or fluid shear stress. Therefore, we tested the hypotheses that ENAP-1 and Hsp90 are the same protein and that BK activation of eNOS is dependent on Hsp90. Immunoblotting of immunoprecipitated Hsp90 with anti-phosphotyrosine antibody shows that Hsp90 is tyrosine-phosphorylated in response to BK stimulation of bovine aortic endothelial cells (BAECs). Coimmunoprecipitation of Hsp90 with anti-eNOS antibody reveals a Hsp90-eNOS complex in endothelial cells under basal conditions that is increased following BK stimulation. Taken together with the tyrosine phosphorylation data, these data suggest that ENAP-1 is Hsp90. BK-stimulated nitric oxide (NO) release is completely blocked by pretreatment with geldanamycin, a specific inhibitor of Hsp90, illustrating the importance of the Hsp90-eNOS interaction. In vitro binding assays with Hsp90-glutathione-S-transferase fusion proteins show direct binding of eNOS with the middle domain (residues 259-615) of Hsp90.

IL-4/IL-13 signaling beyond JAK/STAT

In the past several years, extensive studies on the mechanisms underlying IL-4 and IL-13 signaling have enabled us to gain insight into how these cytokines regulate immune responses. Because both IL-4 and IL-13 use the IL-4Ralpha as a receptor component, these cytokines activate many common signaling pathways. Both of these cytokines use Janus kinases (JAKs) to initiate signaling and activate signal transducer and activator of transcription-6 (STAT6), which is a transcription factor required for many of their biologic functions. In addition to JAK/STAT, these cytokines also activate a variety of other signaling molecules that are important in regulating IL-4-induced proliferation and protection from apoptosis. Suppressor of cytokine signaling-1 (SOCS-1) is a molecule that can inhibit the activation of IL-4 signaling through the inhibition of JAKs. The Fes tyrosine kinase is activated by IL-4 and appears to be important in regulating IL-4-induced proliferation through the phosphorylation of insulin receptor substrate (IRS) molecules. IRS molecules are essential for IL-4-induced proliferation through their ability to recruit phosphoinositol-3 kinase to the activated IL-4 receptor kinase. In addition, IL-4 can activate a number of phosphatases including SH2-containing inositol phosphatase (SHIP), SHP-1, and SHP-2. Finally, B-cell lymphoma gene-6 (BCL-6) appears to regulate a subset of IL-4-induced genes. Thus the biologic responses induced by IL-4/IL-13 require a complex interaction of signaling pathways and regulators.

Weight concern, body image, and abnormal eating in college women tennis players and their coaches

In order to study weight concerns and eating disorders in women tennis players, 107 women tennis players and 26 women's tennis coaches from colleges across the U.S. responded to questionnaires relating to weight concern, body image, and abnormal eating. When evaluating drawings of female figures, players and coaches both considered the ideal body shape to be smaller than the healthiest one. Most players had normal weight, eating habits, and self-esteem; however, they also exhibited noticeable concern about their weight and appearance. Coaches revealed only moderate knowledge of weight related issues, believed such knowledge to be important, recognized that most of their players were of normal weight, and revealed somewhat negative feelings about overweight people. Players and coaches shared a healthy attitude toward tennis. The results of this study do not imply that college women tennis players are at greater risk of eating disorders than other young women, nor that college coaches are encouraging abnormal eating behaviors

Measuring knowledge of school-based occupational therapy

OBJECTIVE

The primary purpose of this study was to develop a measure of Knowledge of Occupational Therapy in School settings (KNOTS) for occupational therapy students. A secondary purpose was to develop a scale of Self-Efficacy in School Settings (SESS) for occupational therapy students.

METHOD

One hundred forty-five university students enrolled in either occupational therapy classes or education classes completed a questionnaire consisting (in part) of the 60-item KNOTS scale and the SESS scale. Analyses of internal reliability, group comparisons, and correlations were computed on the scores.

RESULTS

The reliabilities of the KNOTS (.85) and SESS (.94) were reasonably high. Occupational therapy students performed significantly better than did education students, and senior occupational therapy students scored significantly higher than did juniors on the KNOTS. SESS scores were positively but not significantly correlated with KNOTS scores.

CONCLUSION

If further investigation provides additional evidence for the reliability and validity of the KNOTS and SESS, both measures have a number of potential practical applications.

Regulation of cardiac rhythm in hibernating mammals

The dramatic fall in heart rate exhibited by mammals entering hibernation begins before there is any noticeable fall in body temperature. The initial, progressive decrease in heart rate is the result of a cyclic parasympathetic activation that induces skipped beats and regular asystoles as well as slows the even heart beat. As body temperature subsequently falls, the parasympathetic influence is progressively withdrawn and periods of parasympathetic and sympathetic dominance alternate and give rise to regular periods of arrhythmia (tachycardia followed by bradycardia), and occasional long asystoles or periods of highly irregular cardiac activity. Superimposed on this is a vagally-mediated, respiratory sinus arrhythmia that is accentuated in species that breathe episodically. These events give way to a uniform heart rate in deep hibernation at low temperatures where both parasympathetic and sympathetic tone appear absent. The complete absence of tone is not a function of reduced temperature but is reflective of the state of deep, steady state hibernation. The elevation in heart rate that accompanies the onset of arousal is the result of dramatic increases in sympathetic activation that precede any increases in body temperature. As body temperature then rises, sympathetic influence is slowly withdrawn. Arrhythmias are also common during natural arousals or shifts from lower to warmer hibernation temperatures as periods of parasympathetic and sympathetic dominance again alternate en route to re-establishing a steady state in euthermia. The mechanism behind, and the biological significance of, cardiac changes mediated through orchestrated arrhythmias remain unknown.

Transcriptional repression of Stat6-dependent interleukin-4-induced genes by BCL-6: specific regulation of iepsilon transcription and immunoglobulin E switching

The BCL-6 proto-oncogene encodes a POZ/zinc-finger transcription factor that is expressed in B cells and a subset of CD4(+) T cells within germinal centers. Recent evidence suggests that BCL-6 can act as a sequence-specific repressor of transcription, but the target genes for this activity have not yet been identified. The binding site for BCL-6 shares striking homology to the sites that are the target sequence for the interleukin-4 (IL-4)-induced Stat6 (signal transducers and activators of transcription) signaling molecule. Electrophoretic mobility shift assays demonstrate that BCL-6 can bind, with different affinities, to several DNA elements recognized by Stat6. Expression of BCL-6 can repress the IL-4-dependent induction of immunoglobulin (Ig) germ line epsilon transcripts, but does not repress the IL-4 induction of CD23 transcripts. Consistent with the role of BCL-6 in modulating transcription from the germ line epsilon promoter, BCL-6(-/-) mice display an increased ability to class switch to IgE in response to IL-4 in vitro. These animals also exhibit a multiorgan inflammatory disease characterized by the presence of a large number of IgE(+) B cells. The apparent dysregulation of IgE production is abolished in BCL-6(-/-) Stat6(-/-) mice, indicating that BCL-6 regulation of Ig class switching is dependent upon Stat6 signaling. Thus, BCL-6 can modulate the transcription of selective Stat6-dependent IL-4 responses, including IgE class switching in B cells.

Differences in age, laterality, and Steinberg stage at initial presentation in patients with steroid-induced, alcohol-induced, and idiopathic femoral head osteonecrosis

Comparisons between treatments and studies with regard to femoral head osteonecrosis (ON) are difficult because the demographic characteristics of the patients composing the samples vary greatly. The purpose of this investigation was to determine whether ON initiation and progression were specific for a causative agent. A group of 172 patients (245 hips) was subdivided by causative agent. Patients with alcohol-induced ON were significantly older (average age, 49 years; P = .0001), were men (97%), and presented with collapsed femoral heads (90%). Patients with steroid-induced ON averaged 39 years of age, 49% had bilateral disease, and 62% presented with a collapsed femoral head. Patients with idiopathic ON averaged 40 years of age, 35% had bilateral disease, and 55% presented with a collapsed femoral head. Given the different distributions of ON risk factors at initial presentation, it is likely that successful or unsuccessful outcomes may depend most on the sample receiving the intervention. We therefore recommend stratification of patients by causative agent, Steinberg stage at initial presentation, and presence of unilateral or bilateral disease to help clarify the effects of the various treatments for ON of the femoral head.

Acute exercise can improve cardioprotection without increasing heat shock protein content

The aim of this study was to determine the effects of acute bouts of exercise on myocardial recovery after ischemia and heat shock protein expression. Adult female Sprague-Dawley rats were divided into five groups: 1) 1-day run (1DR; n = 6) and 2) 3-day run (3DR; n = 7), in which rats ran for 100 min at a speed of 20 m/min up a 6 degrees grade for 1 or 3 consecutive days; 3) 1-day cold run (1CR), in which rats ran the same as 1DR but with wet fur at 8 degrees C, which prevented an elevation of core temperature (n = 8); 4) heat shock sedentary (HS), in which rats had their core temperatures raised to 42 degrees C one time for 15 min (n = 5); and 5) sedentary control (n=15). Cardiac function was analyzed 24 h after the last treatment using an isolated, working heart model. Nonpaced hearts were initially perfused under normoxic conditions, then underwent 17 min of global, normothermic (37 degrees C) ischemia, and, finally, were allowed to recover for 30 min under normoxic conditions. The concentration of the 72-kDa heat shock protein (HSP 72) was measured in each left ventricle. Compared with that in the sedentary group, recovery of cardiac output x systolic pressure (CO x SP) was enhanced (P < 0.05) in all treatment groups when the postischemic value was covaried with the preischemic value. No differences in CO x SP were found (P > 0.05) between the following groups: 1DR vs. 3DR, 1DR vs. HS, and 1DR vs. 1CR. Heat shock protein concentration was significantly greater (P < 0.05) than that in the sedentary controls in HS, 1DR, and 3DR groups, but not for 1CR. The concentration of HSP 72 was not significantly correlated with postischemic CO x SP (R2 = 0.197, P > 0.05). We conclude that acute bouts of exercise can produce cardioprotective effects without an elevation of HSP 72.

Treatment of metastatic osteosarcoma at diagnosis: a Pediatric Oncology Group Study

PURPOSE

To estimate the duration of survival (S) of patients with metastatic osteosarcoma (MOS) at diagnosis treated with a multiagent, ifosfamide-containing chemotherapeutic and surgical regimen and to evaluate the toxicity of this regimen.

PATIENTS AND METHODS

Thirty patients aged younger than 30 years received two courses of ifosfamide followed by surgery on the primary tumor and metastatic sites. Patients then received a postsurgical multiagent chemotherapeutic regimen that consisted of high-dose methotrexate (HDMTX), ifosfamide, doxorubicin, and cisplatin.

RESULTS

The 5-year event-free survival (EFS) rate was 46.7% (95% confidence interval [CI]; 28.5 to 64.9) and 5-year S rate was 53.3% (95% CI; 35.1 to 71.5). Three patients with bone metastases and one patient with lymph node metastases died. Twenty-six patients presented with pulmonary metastatic nodules only. Eight of these patients had at least eight nodules at diagnosis and had an estimated 5-year EFS rate of 25.0% compared with 66.7% for the 18 patients with less than eight nodules (P=.06). Fourteen patients presented with bilateral lung metastases and had a 5-year EFS rate of 35.7% compared with the 12 patients who presented with unilateral involvement and had a 5-year EFS rate of 75.0% (P=.03). The hematopoietic toxicity experienced by the patients during the entire regimen was relatively mild. Seven patients had renal toxicity characterized by hypophosphatemia and/or hypokalemia.

CONCLUSION

This ifosfamide-containing regimen is tolerable and effective in the treatment of patients with osteosarcoma (OS) who present with lung metastases. However, better regimens are required for this group of patients.

Consolidation therapy with antimetabolite-based therapy in standard-risk acute lymphocytic leukemia of childhood: a Pediatric Oncology Group Study

PURPOSE

To develop antimetabolite-based consolidation regimens that minimize acute and long-term toxicities and improve the survival rate of children with standard-risk B-lineage acute lymphocytic leukemia (ALL).

PATIENTS AND METHODS

Seven hundred twenty-seven eligible patients with standard-risk early pre-B ALL were registered onto the study. Seven hundred sixteen patients attained a complete remission (CR) after induction therapy. Of these, 114 patients were randomized to a different regimen and were the subject of a separate report. Six hundred two patients were randomized to receive one the following regimens: intermediate-dose methotrexate (IDMTX) with leucovorin rescue on weeks 7, 10, 13, 16, 19, and 22 (regimen A); regimen A plus asparaginase (ASP) administered intramuscularly (i.m.) weekly for 24 weeks (regimen B); or regimen A plus a 24-hour infusion of cytarabine (AraC) with each IDMTX (regimen C). After consolidation, patients were placed on maintenance therapy through week 156. Regimens A and C were opened in February 1986, and regimen B in May 1987. Comparisons are based on concurrently randomized patients (May 1987 to January 1991 between regimens A and B, and February 1986 to January 1991 between regimens A and C).

RESULTS

The 5-year continuous CR (CCR) rates were not significantly different: A versus B, 78.1% (3.9 +/- SE) versus 83.3% +/- 3.5% and A versus C, 79.4% +/- 3.2% versus 83.5% +/- 2.9%; P by one-sided log-rank tests were .27 and .34, respectively. Significant treatment differences were not found with regard to sex, rate of testicular and CNS relapse, or CNS complications. During consolidation, regimen C had significantly more bacterial infections (P = .0032) and days spent in the hospital (P < .001) compared with regimen A.

CONCLUSION

We were unable to show a statistical advantage of adding either ASP or AraC to IDMTX in terms of improvement in event-free survival (EFS).

Topotecan in pediatric patients with recurrent and progressive solid tumors: a Pediatric Oncology Group phase II study

PURPOSE

A phase II study was designed to determine the efficacy of topotecan, an inhibitor of topoisomerase I, in the treatment of patients with progressive or recurrent pediatric extracranial solid tumors (STs).

PATIENTS AND METHODS

Patients younger than 21 years at the time of initial diagnosis with refractory STs were treated with 2 mg/m2 topotecan given by 30-minute infusions for 5 days repeated every 3 weeks. Granulocyte colony stimulating factor (G-CSF) was added to the regimen only after occurrence of severe neutropenia or therapy delay due to sustained neutropenia.

RESULTS

One hundred forty-one patients were treated with 539 courses of topotecan. Responses were seen in 34 patients (3 had complete responses [CRs], 2 had partial responses [PRs], and 24 had minor responses [MRs] or stable disease [SD]). The number of administered courses in patients with SD varied between 5 and 24, with a median of 10. The median time on the study for patients with SD was approximately 8.5 months. In patients without bone marrow involvement, the most frequent toxicity was myelosuppression: hemoglobin < 8 g/dl in 83 of 341 courses, absolute granulocyte count < 1,000/microl in 221 of 341 courses, and platelet count < 50,000/microl in 162 of 341 courses. Nausea and vomiting were infrequent; many patients were pretreated with ondansetron or granisetron. A recurrent rash developed in 16 patients and was usually well controlled with diphenhydramine and hydrocortisone. G-CSF was administered in 203 of 539 courses because of neutropenia. Therapy was delayed over 1 week in 33 instances.

CONCLUSION

In previously treated patients, topotecan produced CRs and PRs in patients with neuroblastoma, Ewing's tumor, and retinoblastoma. In hepatoblastoma, rhabdomyosarcoma, and a few rare tumors, long-lasting MRs and SDs with excellent symptom control were seen. The toxicity of topotecan, predominantly myelosuppression, was tolerable.

Parent's behaviors, knowledge, and beliefs related to unintentional firearm injuries among children and youth in the southwest

INTRODUCTION

The purpose of this research study was to describe parents' behaviors, knowledge, and beliefs related to unintentional firearm injuries among children and youth.

METHOD

A convenience sample of 80 parents whose children were attending one of six Kindercare Learning Centers in a Southwestern city was surveyed during the summer of 1995 to learn about their behaviors, knowledge and beliefs about unintentional firearm injuries among children and youth. Data on demographic characteristics, behaviors, knowledge, and beliefs, were collected with a questionnaire.

RESULTS

Men and parents who had grown up with a gun in the house were more likely to be gun owners. Forty-eight percent of parents kept at least one gun in the home. Twenty-six percent of gun owners reported that the gun was loaded at all times, and 18% reported that a gun was kept within reach of a child. The most common reason given by parents for having a gun was for protection (61%). Only 8% of parents reported having discussed firearm safety with a health care worker. None of the parents had discussed firearm safety with a pediatrician. A test of knowledge about firearm injuries revealed some gaps in knowledge, with no significant differences between men and women or gun owners and non-gun owners.

DISCUSSION

Results suggest that firearms in the home continue to pose a significant risk to children. Anticipatory guidance from NPs and pediatricians is needed to protect children from unintentional firearm injuries.

Controlling receptor-ligand contact to examine kinetics of T cell activation

A method for controlling the contact of cell-surface receptors with immobilized ligands has been developed. Cells are trapped in an asymmetric liquid film that can be quantitatively thinned by reducing the film's capillary pressure. Ligands adsorbed to the liquid-solid interface are forced into increasingly tighter contact with the cells as the air-liquid interface is drawn down. Controlling the degree of thinning allows study of repulsive forces, and controlling its time course produces a definite time 0 for analyzing signal transduction. This system was tested by examining the time course of calcium mobilization in T cells upon activation with anti-CD3 antibody at different dilutions and ionic strengths. The averaged calcium transient of the responding cells was essentially the same for each condition. However, the fraction of responding cells decreased with anti-CD3 dilution, and indicated that the critical ligand density for T cell activation lies between approximately 35 and 70 molecules of anti-CD3 per microm2. Decreasing the medium's ionic strength from the normal value of 157 mM to 57 mM did not affect either the average calcium response profile or the fraction of responding cells, but strongly affected receptor-ligand contact, decreasing the percent of spontaneous activation from 38% to 5%. Such an imposed decrease sets the stage for film thinning to impose much greater control of receptor-ligand contact.

Do descending influences alternate to produce episodic breathing?

This study examines the episodic breathing patterns of three disparate groups of vertebrates. In an in vitro bullfrog brainstem-spinal cord preparation, episodic breathing was replaced by uniformly spaced breaths following transection caudal to the optic chiasma. The same effect was produced in hibernating squirrels by inhalation of mild anesthesia. Preliminary data suggest that a similar conversion is also produced in hibernating squirrels by vagotomy, in conjunction with blockade of central NMDA-type glutamate receptors. In all cases, even though overall breathing frequency increased, due to elimination of periods of apnea, instantaneous breathing frequency slowed. Seals breathe episodically in sleep and when these animals awaken after the start of a breathing episode, breathing also immediately slows. The data presented here are consistent with the suggestion that in all vertebrates, higher centres can modulate the central rhythm generator for breathing, in both a positive and a negative fashion. During episodic breathing, in the species studied here, these modulating influences alternate in a fashion that produces periods of apnea alternating with periods of relatively high frequency ventilation.

'Clearing' cervical spine injuries in polytrauma patients: is it really safe to remove the collar?

Polytrauma patients are at increased risk for occult cervical spine injuries. Those unable to provide clinical clues to injury either remain in hard collars until they are able to cooperate with the physical examination or are deemed "clear of cervical injury" if the emergency room screening radiographs are without obvious bony abnormality. Cervical immobilization for a lengthy period of time is not without morbidity. Missed ligamentous injuries can lead to cervical instability, which in turn can result in permanent neurologic sequelae. This article reviews the current methodologies to "clear the cervical spine" and highlights the inadequacies.