Subchronic dietary toxicity of strychnine: bobwhite quail are less sensitive than mallard ducks

PURPOSE: This study was undertaken to evaluate in vivo the effect of recombinant hirudin (r-hirudin [HBW 023]), a potent thrombin inhibitor, on the process of microvascular thrombus formation and recanalization. METHODS: Thrombosis was induced photochemically in distinct arterioles (n = 25) and venules (n = 30) of the ear of 16 hairless hr/hr mice (8 to 10 weeks old, 25 to 30 g of body weight). r-Hirudin (1 mg/kg of body weight) was administered intravenously directly before thrombus induction; saline-treated animals served as controls. Thrombus formation (i.e., first platelet deposition at the endothelial lining [FPD]; inner luminal diameter reduction to 50% [D/2]; complete vessel occlusion [CVO]), vessel recanalization, microcirculatory parameters, and leukocyte-endothelial cell interaction were analyzed by means of intravital fluorescence microscopy. RESULTS: Hirudin significantly delayed the process of thrombus formation compared with saline-treated controls in both arterioles (FPD: 381 +/- 80 vs 137 +/- 25 seconds, P < 0.05; D/2: 627 +/- 49 vs 501 +/- 71 seconds; CVO: 925 +/- 78 vs 854 +/- 60 seconds) and venules (FPD: 173 +/- 11 vs 59 +/- 4 seconds; D/2: 342 +/- 54 vs 228 +/- 27 seconds; CVO: 541 +/- 85 vs 344 +/- 43 seconds; P < 0.05). In addition, r-hirudin-treated animals showed an increased rate of vessel recanalization at 24 hours after thrombus induction (arterioles: 54% [7 of 13] vs 0% [0 of 12], P < 0.05; venules: 77% [10 of 13] vs 53% [9 of 17]), whereas microcirculatory parameters and leukocyte-endothelial cell interaction were not affected. CONCLUSION: Our data indicate that r-hirudin not only counteracts the process of thrombus formation but also promotes vessel recanalization, thus supporting its use in clinical microvascular surgery.     

Posterior C1-C2 transarticular screw fixation for atlantoaxial arthrodesis

OBJECTIVE: To assess the outcomes associated with C1-C2 transarticular screw fixation. METHODS: The clinical outcomes of 121 patients treated with posterior C1-C2 transarticular screws and wired posterior C1-C2 autologous bone struts were evaluated prospectively. Atlantoaxial instability was caused by rheumatoid arthritis in 48 patients, C1 or C2 fractures in 45, transverse ligament disruption in 11, os odontoideum in 9, tumors in 6, and infection in 2. RESULTS: Altogether, 226 screws were placed under lateral fluoroscopic guidance. Bilateral C1-C2 screws were placed in 105 patients; each of 16 patients had only one screw placed because of an anomalous vertebral artery (n = 13) or other pathological abnormality. Postoperatively, each patient underwent radiography and computed tomography to assess the position of the screw and healing. Most screws (221 screws, 98%) were positioned satisfactorily. Five screws were malpositioned (2%), but none were associated with clinical sequelae. Four malpositioned screws were reoperated on (one was repositioned, and three were removed). No patients had neurological complications, strokes, or transient ischemic attacks. Long-term follow-up (mean, 22 mo) of 114 patients demonstrated a 98% fusion rate. Two nonunions (2%) required occipitocervical fixation. In comparison, our C1-C2 fixations with wires and autograft (n = 74) had an 86% union rate. CONCLUSION: Rigidly fixating C1-C2 instability with transarticular screws was associated with a significantly higher fusion rate than that achieved using wired grafts alone. The risk of screw malpositioning and catastrophic vascular or neural injury is small and can be minimized by assessing the position of the foramen transversaria on preoperative computed tomographic scans and by using intraoperative fluoroscopy and frameless stereotaxy to guide the screw trajectory.     

Will evidence-based nursing practice make practice perfect?

Evidence-based practice, or evidence-based decision-making, is rapidly developing as a growth industry in nursing and the health professions more widely. It has its origins in the work of the British epidemiologist Archie Cochrane and has recently been re-energized in Canada by the National Forum on Health and its call for a culture of evidence-based decision-making. Before we adopt evidence-based nursing (EBN) as a mantra for the 21st century, we should examine its origins and its consequences, and we should probe related concepts, 2 of which are the nature and structure of practice-based knowledge and the nature and structure of evidence generally. Findings of a recent survey of nurses in western Canada are used to illustrate that nurses use a broad range of practice knowledge, much of which is experientially based rather than research-based.     

Patterns of general health care and STD services use among high-risk youth in Denver participating in community-based urine chlamydia screening

BACKGROUND: In the United States, youth are at highest risk for STDs, and innovative programs have been called for to increase their access to essential STD-related services. To guide the development of such programs, locally relevant information is needed on current use of general health care and STD services in this population. GOAL: To study access to and use of general health care and STD services in a purposive sample of high-risk youth in inner-city Denver. STUDY DESIGN: An interview-based survey conducted as part of a community program for urine chlamydia screening targeting black and Hispanic youth 13 years to 25 years. RESULTS: Of 221 sexually experienced youth in the survey, 72% had accessed general health services in the past year and 39% reported an STD evaluation at any time in the past. Community and school clinics were reported by 50% as a source for general health care and by 62% as a source for STD services. STD clinics were reported by only 14% as a source for STD services. Routine checkups were the most important reasons to seek general health care, yet of those who went for a routine checkup, only 34% reported an STD evaluation. Although few barriers appeared to exist in accessing general health care, anticipated anxiety about procedures and results formed the major barrier to accessing STD services. CONCLUSIONS: Use of general health services was common in this population of high-risk adolescents; however, the provision of STD services as part of general health care visits appeared to be low. On the basis of these findings, a comprehensive STD prevention strategy may be envisioned, which would include provider interventions to increase the provision of STD prevention services in general health care settings; community interventions to enhance access to general health care and STD services; and community-based screening programs for those not able or willing to seek clinic-based services.     

High-flow bypass using nonocclusive excimer laser-assisted end-to-side anastomosis of the external carotid artery to the P1 segment of the posterior cerebral artery via the sylvian route. Technical note

In a patient with a giant aneurysm of the basilar artery trunk, a vein graft was interposed between the external carotid artery in the neck and the P1 segment of the posterior cerebral artery. Balloon occlusion of both vertebral arteries was performed 3 days later. The sylvian route was used for the grafting procedure and the connection to the posterior cerebral artery was made by using the excimer laser-assisted nonocclusive anastomosis technique.     

Mast cell collagenase correlates with regression of pulmonary vascular remodeling in the rat

Pulmonary vascular remodeling, produced by cell hypertrophy and extracellular matrix protein synthesis in response to hemodynamic stress, regresses after reduction of blood pressure, possibly by proteolysis of structural proteins. To test this postulate, we assessed the breakdown of extracellular matrix proteins and expression of collagenase and elastase in pulmonary arteries of rats exposed to hypoxia (10% O2 for 10 d) followed by normoxia. During hypoxia, contents of collagen and elastin increased in pulmonary arteries and latent rat interstitial collagenase was expressed without increased collagenolytic activity or mRNA levels. At 3 days after normoxia, collagen and elastin contents decreased coincident with the new appearance of activated collagenase and transient increases in collagenolytic and elastolytic activities. The amount of immunoreactive collagenase, localized predominately in connective tissue-type mast cells, was increased in the adventitia and media of hypertensive vessels. We conclude that mast cells containing latent collagenase are recruited into the outer walls of pulmonary arteries during remodeling. It is possible that mast cell-derived collagenase contributes to collagen breakdown in pulmonary arteries during early recovery from hypoxia and plays a role in restoration of vascular architecture.     

Three-dimensional ultrasonography in obstetrics and gynecology: preliminary experience

OBJECTIVE: Technologic advances in ultrasonographic imaging have revolutionized the management of women's health care. We recently began to evaluate the clinical applications of three-dimensional ultrasonography. STUDY DESIGN: This study prospectively evaluated 161 obstetric and gynecologic patients. Both two- and three-dimensional imaging data were acquired from real-time ultrasonography. Three orthogonal planes were displayed on a monitor and were used to create the rendered three-dimensional images. RESULTS: To date, 201 three-dimensional ultrasonographic studies have been performed, 165 transabdominally and 36 transvaginally. Transabdominally, an average of eight acquisitions per patient were obtained. Of the clinically suspected abnormalities, 29 of 32 (91%) were confirmed by three-dimensional imaging. Three of 32 (9%) improved the diagnostic capabilities or changed the diagnosis. Of the 36 transvaginal studies, an average of four acquisitions per patient were done. Thirty (83%) of these patients had suspected abnormalities and all were confirmed. CONCLUSIONS: Three-dimensional ultrasonographic imaging appears to be highly promising in the clinical setting.     

Retrograde cerebral perfusion enhances cerebral protection during prolonged hypothermic circulatory arrest: a study in a chronic porcine model

BACKGROUND: This study was undertaken to confirm earlier findings that retrograde cerebral perfusion (RCP) can improve cerebral outcome after prolonged hypothermic circulatory arrest (HCA), and to determine whether RCP with inferior vena caval occlusion, which is more effective in removing particulate emboli, is superior to conventional RCP in enhancing cerebral protection. METHODS: Sixty-two pigs (27 to 30 kg) were randomly assigned to undergo one of the following for 90 minutes at 20 degrees C: antegrade cerebral perfusion (ACP); conventional RCP (RCP); RCP with occlusion of the inferior vena cava (RCP-O), or HCA with the head packed in ice. RCP flow was regulated to a sagittal sinus pressure of 20 mm Hg. Hemodynamic, electrophysiologic, and metabolic monitoring were carried out until 4 hours after rewarming, daily behavioral and neurologic assessments until elective sacrifice on day 7, and histologic analysis of the brain after death. RESULTS: Complete behavioral recovery was seen in all surviving animals by day 5 after ACP or RCP, but in only 83% after RCP-O and 50% after HCA (p = 0.001). A histopathologic score of 2 or more, indicating more than mild injury, was not found in any animal after ACP, in 27% after RCP, in 47% after HCA, and in 68% after RCP-O (p = 0.002). The median oxygen consumption was 6.66 mL/min after ACP, 1.37 mL/min with RCP, and 1.02 mL/min with RCP-O (p < 0.0001). The median amount of fluid sequestered was 2,450 mL after RCP-O, 760 mL after RCP, and -200 mL after ACP (p < 0.0001). CONCLUSIONS: Conventional RCP without inferior vena caval occlusion results in a significantly better outcome than RCP-O after prolonged HCA, despite more efficient cerebral perfusion during RCP-O, and also provides cerebral protection superior to prolonged HCA alone, but care must be taken during its implementation to minimize cerebral edema and other possible causes of retroperfusion-related cerebral injury.     

Syndrome of inappropriate antidiuretic hormone associated with vinorelbine therapy

OBJECTIVE: To describe onset of syndrome of inappropriate antidiuretic hormone (SIADH) associated with vinorelbine therapy for advanced breast cancer. CASE SUMMARY: A 50-year-old white woman with a history of advanced breast cancer refractory to other treatment modalities was receiving vinorelbine. Blood chemistries revealed severely depleted sodium and potassium concentrations from a normal baseline within a 7-day period. A recheck of blood chemistries confirmed hyponatremia. The patient was admitted to the hospital and treated for SIADH. After successful treatment, she was given demeclocycline prophylactically and rechallenged with vinorelbine without recurrence of the syndrome. DISCUSSION: SIADH has been reported as a complication of treatment with vinca alkaloids. To our knowledge, this is the first report of this syndrome related to vinorelbine therapy. CONCLUSIONS: Because of its structural similarity to the other vinca alkaloids, vinorelbine is believed to be responsible for SIADH in our patient. Clinicians should be aware of the possibility that vinorelbine may cause SIADH and possibly hypokalemia.     

Pooling of urine samples for screening for Neisseria gonorrhoeae by ligase chain reaction: accuracy and application

The accuracy of detection of genital Neisseria gonorrhoeae infection in pooled urine samples by ligase chain reaction (LCR) was examined in three populations. Firstly, urine specimens from 300 female military recruits (FMR) were tested by LCR individually and in pools of four and six. Secondly, 300 urine specimens from middle-school students (MSS) were tested individually by LCR, and then the processed specimens were stored frozen for subsequent testing in pools of 4 and 10. Thirdly, 600 frozen urine specimens from high-school students (HSS) were tested by using the LCR pooling algorithm, i.e., testing processed specimens in pools of four in one test unit dose, and retesting individual specimens from positive pools. Finally, the pooling algorithm results were compared to culture results for a subset of 344 students from the original 600 HSS from whom cervical or urethral samples were taken at the discretion of the school nurse practitioners. Compared to individual testing of specimens by LCR in the FMR population, the pooling-by-four algorithm was 100% sensitive (5 of 5) and 100% pool specific (70 of 70), and the pool-by-six algorithm was 100% sensitive (5 of 5) and 100% pool specific (45 of 45). In the MSS population, the pool-by-4 algorithm was 95.8% sensitive (23 of 24) and 100% (52 of 52) pool specific, and the pool-by-10 algorithm was 95.8% sensitive (23 of 24) and 100% (17 of 17) pool specific. In the subset of 344 HSS from whom endocervical or urethral specimens were collected for culture, 31 were positive by LCR in urine and 26 were positive by culture. After results discrepant between culture and LCR were adjudicated by a confirmatory LCR test, the pooling algorithm was 93.8% (30 of 32) sensitive and 99.7% (311 of 312) specific. Culture from these 344 HSS was 81.3% (26 of 32) sensitive. The pooling algorithm reduced the cost of the N. gonorrhoeae LCR assay by 60% compared to individual testing of the HSS specimens and was both sensitive and specific.