CNS Hypomyelination Disrupts Axonal Conduction and Behavior in Larval Zebrafish.

Myelination is essential for central nervous system (CNS) formation, health and function. As a model organism, larval zebrafish have been extensively employed to investigate the molecular and cellular basis of CNS myelination, because of their genetic tractability and suitability for non-invasive live cell imaging. However, it has not been assessed to what extent CNS myelination affects neural circuit function in zebrafish larvae, prohibiting the integration of molecular and cellular analyses of myelination with concomitant network maturation. To test whether larval zebrafish might serve as a suitable platform with which to study the effects of CNS myelination and its dysregulation on circuit function, we generated zebrafish myelin regulatory factor (myrf) mutants with CNS-specific hypomyelination and investigated how this affected their axonal conduction properties and behavior. We found that myrf mutant larvae exhibited increased latency to perform startle responses following defined acoustic stimuli. Furthermore, we found that hypomyelinated animals often selected an impaired response to acoustic stimuli, exhibiting a bias toward reorientation behavior instead of the stimulus-appropriate startle response. To begin to study how myelination affected the underlying circuitry, we established electrophysiological protocols to assess various conduction properties along single axons. We found that the hypomyelinated myrf mutants exhibited reduced action potential conduction velocity and an impaired ability to sustain high-frequency action potential firing. This study indicates that larval zebrafish can be used to bridge molecular and cellular investigation of CNS myelination with multiscale assessment of neural circuit function.SIGNIFICANCE STATEMENT Myelination of CNS axons is essential for their health and function, and it is now clear that myelination is a dynamic life-long process subject to modulation by neuronal activity. However, it remains unclear precisely how changes to myelination affects animal behavior and underlying action potential conduction along axons in intact neural circuits. In recent years, zebrafish have been employed to study cellular and molecular mechanisms of myelination, because of their relatively simple, optically transparent, experimentally tractable vertebrate nervous system. Here we find that changes to myelination alter the behavior of young zebrafish and action potential conduction along individual axons, providing a platform to integrate molecular, cellular, and circuit level analyses of myelination using this model.

Morbidity associated with ORIF of intra-articular calcaneus fractures using a lateral approach.

This is a review of 183 patients with 218 displaced intraarticular fractures of the calcaneus treated by open reduction and internal fixation. One hundred and ninety four (89%) wounds underwent primary uneventful healing. Twenty-four wounds (11%) required local wound care. One deep infection occurred in a neuropathic foot that required below-knee amputation. No free-tissue transfers, local tissue flaps or skin grafts were needed in patients who presented initially with a closed fracture. Ninety-five fractures (43.5%) required subsequent surgical procedures (hardware removal-88/95 [93% of secondary procedures]). Six patients (2.8%) had postoperative sural nerve findings. Seventeen procedures other than hardware removal were performed. There were five subtalar fusions including two subtalar distraction bone-block arthrodeses. There were seven claw toe correction procedures, four calcaneal valgus osteotomies for varus malunions and one subtalar arthrolysis at the time of hardware removal. These results suggest internal fixation of displaced intra-articular calcaneus fractures using a single lateral approach is a safe, reliable method of treatment.

Peroneus brevis rotation flap: anatomic considerations and clinical experience.

BACKGROUND: Large soft tissue defects of the distal third of the leg are common occurrences at trauma centers. Massive defects often require vascularized free tissue transfer for coverage; however, smaller defects may frequently be closed by rotation of local tissue. The peroneus brevis muscle is ideally located to provide coverage of the exposed distal fibula. METHODS: An anatomic dissection of the peroneus brevis muscle and its vascular pedicles was performed in 10 fresh cadaveric leg specimens. Patients who underwent this procedure at our institution were retrospectively reviewed. RESULTS: Each dissected muscle had an average of 3.5 vascular pedicles (range, 2-6), which arose from the peroneal artery in all but two cases. The average distance of the distal pedicle from the tip of the lateral malleolus was 6.7 cm (range, 3.5-12.0 cm). The muscle belly ended an average of 6.0 mm proximal to the tip of the lateral malleolus. Half of the specimens had muscle bellies that extended to or past the tip of the lateral malleolus. This rotation flap has been successful in covering four wounds with exposed distal fibula in four patients. CONCLUSION: The anatomic characteristics of the peroneus brevis muscle are ideal for soft tissue coverage of the distal fibula. Ease of elevation and reliability have made this rotational flap the procedure of choice for small soft tissue defects over the distal fibula at our institution.

Barriers to smoking cessation initiatives for Medicaid clients in managed care.

In this paper, key barriers to providing smoking cessation services for low income individuals are illustrated using epidemiologic data from a population which was enrolled in a Medicaid managed care plan in Kansas during 1998. The Plan served 623 pregnant women who could potentially benefit from assistance in avoiding tobacco exposure. The prevalence of smoking among adult clients was 44.8%. twice the national average. Only 52.3% of adult smokers were advised by a provider to quit in the previous year. Most individuals in the client population (81.7% of the 10,733 members) were children, suggesting the importance of targeting environmental tobacco smoke exposure in order to reduce morbidity from asthma. The adult household member who needed smoking cessation services, however, was unlikely to qualify for health care benefits through Medicaid. The median length of enrollment was only 1.9 months, providing very little client contact time for tobacco control initiatives. The literature suggests that some providers may lack skills in treating tobacco as an addiction. It would be a major task for the managed care organization to train the 2,000 physicians in 68 of the 105 counties of Kansas who cared for this population. Potential solutions include improving reimbursement for smoking prevention and treatment, and developing cheaper smoking cessation services which are effective and acceptable among low-income individuals. The managed care organization could provide patient education materials and staff training for physicians and other members of the office staff.

Treatment of affective disorder and obesity with topiramate.

OBJECTIVE: To report a case of weight loss and mood stabilization in a patient being treated with the antiepileptic drug topiramate. CASE SUMMARY: A 37-year-old obese white woman with affective instability and obesity was being treated with adjunctive topiramate therapy. The patient lost 10 kg over 10 weeks of treatment with topiramate and improved clinically, as evidenced by a reduction in the number of times that she had to be admitted to a management unit for constant observation, and a decrease in the number of times that mechanical restraints or medication interventions were required for aggressive outbursts. Furthermore, the patient successfully completed two home visits while receiving topiramate therapy and was out of the hospital on her third home visit at the time of this writing. DISCUSSION: This case further strengthens previous reports that topiramate may be useful in treating affective disorders as well as inducing weight loss in a patient population in which weight gain is common. The patient discussed in this case report had no acute illnesses or changes in health status, no changes in diet, and no changes in her medications that could have accounted for the sudden weight loss. In addition, the patient's behavior did not improve until topiramate was added as adjunctive therapy of valproic acid, citalopram, and chlorpromazine during an adequate trial period. CONCLUSIONS: Controlled studies need to be performed to evaluate the use of topiramate in the psychiatric population and, in particular, the benefits of topiramate therapy in psychiatric patients with an additional diagnosis of obesity.

Evaluation of the influence of diabetes mellitus on antipyrine metabolism and CYP1A2 and CYP2D6 activity.

STUDY OBJECTIVE: To evaluate the metabolism of antipyrine, a general metabolic probe, caffeine, a probe for cytochrome P450 (CYP) 1A2 and N-acetyltransferase activity, and dextromethorphan, a specific probe for CYP2D6 activity in patients with type 1 or 2 diabetes mellitus. DESIGN: Prospective, controlled study. SETTING: Research facility. Patients. Fifteen patients with type 1 and 16 with type 2 diabetes, and 16 healthy controls. INTERVENTION: Each subject simultaneously received antipyrine 10 mg/kg, caffeine 100 mg, and dextromethorphan 30 mg. MEASUREMENTS AND MAIN RESULTS: The pharmacokinetics of antipyrine and its primary metabolites were determined from saliva and urine samples. Type 1 diabetes had marked effects on antipyrine metabolism whereas type 2 disease did not alter the metabolism of any of the probe drugs. The apparent oral clearance of antipyrine was increased 72% in patients with type 1 disease compared with controls (p=0.0001). In addition, formation clearances of 4-hydroxyantipyrine and 3-hydroxymethylantipyrine were increased by 74% and 137% in those patients relative to controls. The caffeine metabolic index (paraxanthine/caffeine) was increased 34% (p=0.11), and N-acetylation and CYP2D6 phenotype were not altered. CONCLUSION: The metabolism of antipyrine is increased in patients with type 1 diabetes. Based on in vitro reports of antipyrine metabolism and current caffeine metabolic index data, the predominant effect of type 1 diabetes appears to be an increase in CYP1A2 activity. Assessment of the effect of the disease on other specific CYP metabolic pathways is warranted.

Structure-activity relationship of alkyl camptothecin esters.

The cytotoxicity of camptothecin (CPT) esters 1-6 was measured. Like parental camptothecin, esters 2 and 3, but not 1, 4, 5, and 6, inhibited proliferation of human leukemia cells in culture and induced programmed cell death as assessed by flow cytometry studies. Exhibition of similar levels of antiproliferative activities of CPT 2 and 3 required different incubation time periods in cell cultures, with CPT and 3 requiring the shortest and longest periods, respectively. Both 2 and 3 were inactive against cells resistant to the semisynthetic CPT derivative 9-nitrocamptothecin and unable to stabilize DNA-topoisomerase I (Topo I) "cleavable complexes" in a cell-free system, suggesting that Topo I activity was required but insufficient for the mechanism of action of 2 and 3. Mouse liver homogenate converted esters to parental CPT, but the conversion rates were different with different esters. Of four tested esters in this experiment, ester 2 had the fastest conversion rate. In vivo studies showed that ester 2 had an exceptional lack of toxicity in nude mice, even at enormous doses, and demonstrated extensive activity against human breast and colon tumors grown as xenografts in immunodeficient nude mice, whereas no antitumor activity was observed for the other esters. In conclusion, ester 2 is a prodrug of the antitumor compound CPT, and it can be administered at very high doses in mice with no appearance of toxicity. This study provides a basis for further evaluation of CPT ester 2 as an investigational anticancer agent.

Attitudes, values, beliefs, and practices surrounding end-of-life care in selected Kansas communities.

OBJECTIVE: This study was designed to better meet end-of-life care needs for patients and their families in rural Kansas communities. METHODS: Initially, statistical information indicated an underutilization of hospice services in rural communities. To evaluate the data, focus groups were conducted in targeted communities in order to determine attitudes, values, beliefs, and practices surrounding end-of-life care. A script was developed using established focus group protocols. Each focus group was recorded and the tapes were transcribed. Transcripts were reviewed and categorized for similarities and emerging key issues. RESULTS: Five major areas of concern were identified using this methodology. Major concerns were: (1) participants believed that control over decisions about care at the end of life is the patient's right; (2) while participants saw a need for advance directives, they avoided using them; (3) group participants believed that the patient's wishes should be given first priority and this was viewed as a patient's right; (4) there was an expressed lack of trust in the existing health care system and its providers; and (5) participants expressed more fear over the manner of death than death itself. They fear a technological death as opposed to a good death. CONCLUSIONS: The values most important to the group participants included: freedom and independence, trust, honesty, the right to information, and the importance of family. This information will be utilized in the development of programs and interventions to effect changes in end-of-life care, not only in Kansas, but also in areas with a comparable population.

Raloxifene: a selective estrogen receptor modulator.

Raloxifene is a selective estrogen receptor modulator that produces both estrogen-agonistic effects on bone and lipid metabolism and estrogen-antagonistic effects on uterine endometrium and breast tissue. Because of its tissue selectivity, raloxifene may have fewer side effects than are typically observed with estrogen therapy. The most common adverse effects of raloxifene are hot flushes and leg cramps. The drug is also associated with an increased risk of thromboembolic events. The beneficial estrogenic activities of raloxifene include a lowering of total and low-density lipoprotein cholesterol levels and an augmentation of bone mineral density. Raloxifene has been labeled by the U.S. Food and Drug Administration for the prevention of osteoporosis. However, its effects on fracture risk and its ability to protect against cardiovascular disease have yet to be determined. Studies are also being conducted to determine its impact on breast and endometrial cancer reduction.

Early wound complications of operative treatment of calcaneus fractures: analysis of 190 fractures.

OBJECTIVES: The purpose of the present study was to discover any associations between preoperative variables and the occurrence of wound complications in the surgical treatment of calcaneus fractures. DESIGN: Retrospective review. SETTING: A Level 1 trauma center. PATIENTS: One hundred seventy-nine patients, with 190 fractured calcanei, were studied. INTERVENTION: Each patient underwent open reduction and internal fixation for calcaneus fractures with standard techniques. MAIN OUTCOME MEASUREMENTS: The age, sex, preexisting medical conditions, social history, and mechanism of injury of each patient were recorded. Note was made of the status of the soft tissue injury, if any. The time from injury to surgical stabilization was recorded, as was the type of incision used, use of preoperative antibiotics, and type of wound closure. The patients' records were reviewed for wound complications. These complications were classified as those that could be treated nonsurgically and those that required surgical management. RESULTS: Records from July 1992 to July 1998 showed 179 patients who underwent operative stabilization of a calcaneus fracture. Eleven had bilateral fractures, for a total of 190 fractured calcanei. The average age was thirty-five years. Nine patients were diabetics. One hundred eleven of the patients reported current use of cigarettes. Eighteen of the fractures were open. A standard, L-shaped lateral approach to the calcaneus was used in each case. Stabilization was achieved by using standard techniques, with plates and screws. In all cases, a two-layer wound closure was used. Forty-eight patients (25 percent) developed some form of wound complication. Forty (21 percent) of these required surgical treatment. Statistical analysis identified diabetes (p = 0.02; relative risk 3.4), smoking (p = 0.03; relative risk 1.2), and open fractures (p < 0.0001; relative risk 2.8) as risk factors for wound complication. The presence of more than one risk factor increased the relative risk of a wound complication requiring surgery. CONCLUSION: Smoking, diabetes, and open fractures all increase the risk of wound complication after surgical stabilization of calcaneus fractures. Cumulative risk factors increase the likelihood of wound complications. Patients who have the risk factors identified in this study should be counseled as to the possible complications that may arise after surgery. In patients with multiple risk factors, consideration should be given to nonsurgical management.

Transmetatarsal and midfoot amputations.

The objective of lower extremity amputation surgery is to create a viable, functional residual limb to maximize patient mobility and independence. When part or all of the forefoot is lost to trauma, infection or gangrene, and the hindfoot is viable, every attempt should be made to preserve as much foot function as possible. The use of the transmetatarsal level is common. In the past, amputations through the Lisfranc and Chopart's joint lines involved significant complication rates. With improvements in patient selection and surgical technique, these two amputation levels are viable options to consider when attempting salvage of the hindfoot structures.

An acute intratracheal selenium study: immediate effects on respiration in guinea pigs.

Pulmonary function was assessed in non-sensitized male guinea pigs (206-445 g) before and after intratracheal (ITr) treatment with saline or selenium (Se, 0.06 mg/100 g body weight) as selenium dioxide (SeO2) or seleno-L-methionine (SeM). Pulmonary functional parameters such as the respiratory rate (f), tidal volume (TV), dynamic lung compliance (Cdynl) and lung resistance (Rl) were determined using the respiratory flow (F) signal and the transpulmonary signal obtained via the intrapleural pressure (P) from the animal. Although, pulmonary dysfunction was observable with exposure to two different Se compounds, the SeO2-induced changes in f and Rl were significant (P < 0.05). Treatment with SeM did not result in alteration of any of the parameters significantly. Results indicated that acute ITr SeO2 exposure affects respiration precipitated by a significantly decreased f and an increased Rl unlike after SeM. The Cdynl did not change significantly after treatment with either of the two Se compounds. Comparing the immediate effects of the two different Se compounds on respiration, acute ITr SeO2 exposure was found to be more detrimental to pulmonary function than SeM.

Treating to meet NCEP-recommended LDL cholesterol concentrations with atorvastatin, fluvastatin, lovastatin, or simvastatin in patients with risk factors for coronary heart disease.

BACKGROUND: Our study compared use of atorvastatin, fluvastatin, lovastatin, and simvastatin for lowering low-density lipoprotein (LDL) cholesterol concentration in patients at risk for coronary heart disease (CHD). The goal was to reach the LDL cholesterol levels recommended by the National Cholesterol Education Program (NCEP). METHODS: A combined total of 344 men and women took part in this 54-week, multicenter, open-label, randomized, parallel-group, active-controlled, treat-to-target study. Patients were selected on the basis of their LDL cholesterol concentration and their risk for CHD. During treatment, doses were titrated at 12-week intervals to a maximum of 80 mg per day of atorvastatin and lovastatin, or 40 mg per day of fluvastatin and simvastatin, with colestipol added if necessary to attain the NCEP-recommended LDL cholesterol concentration. RESULTS: At the starting dose, atorvastatin decreased plasma LDL cholesterol significantly (P < .05) compared with the other reductase inhibitors, and the percentage of patients reaching target LDL cholesterol concentration at the starting dose was significantly greater in the atorvastatin group (P < .05). Overall, a significantly (P < .05) greater percentage (95%) of atorvastatin-treated patients achieved target LDL cholesterol concentration. The safety profile was similar among all reductase inhibitors tested. CONCLUSIONS: At the starting dose, a significantly (P < .05) greater percentage of atorvastatin-treated patients at risk for CHD reached the target LDL cholesterol concentration than patients with treated with other reductase inhibitors.

Altered sensitivities to anticancer and differentiation agents in etoposide-resistant human myeloid leukemia U-937 cells.

We previously have exposed U-937 human leukemia cells to stepwise increased concentrations of the anticancer drug etoposide, and this treatment has resulted in stable sublines (termed U-937/RE) exhibiting various extents of resistance to the drug and constitutively expressing c-fms mRNA, a specific marker of monocytic differentiation. In this report, we pursued studies to show that the P-glycoprotein blocker, verapamil, partially restores sensitivity to etoposide in U-937/RE cells. Further, the U-937/RE cells exhibit differential sensitivities to compounds that induce maturation of U-937 cells, as judged by the ability to reduce nitroblue tetrazolium and by morphologic changes, and increased sensitivities to apoptosis induction by the cytokines tumor necrosis factor (TNF) and lymphotoxin (LT) and the anticancer drugs 9-nitrocamptothecin and doxorubicin. In addition, the U-937/RE cells, xenografted in immunodeficient mice, demonstrate decreased or no ability to induce tumors. Taken together, these findings indicate that U-937/RE cells differ from the parental U-937 cells in several functional properties and can serve as models to develop protocols for treatment of human leukemia.

Effect of variations in calcaneocuboid fusion technique on kinematics of the normal hindfoot.

Calcaneocuboid fusion with lengthening of the lateral column of the foot has been advocated as a method of treating flatfoot deformity. This study was designed to determine how the length of the lateral column chosen or the position of the foot selected when performing this fusion affect hindfoot kinematics in normal cadaver feet. An electromagnetic tracking system was used to monitor the positions of the talus, calcaneus, navicular, and cuboid while the intact cadaver feet were moved passively and then under reproducible loads. Calcaneocuboid fusion was then performed on these feet first with the feet in neutral position and the lateral column of normal length, then lengthened 10 mm or shortened 5 mm, and then with the lateral column lengthened 10 mm and the feet positioned in plantar flexion and eversion or dorsiflexion and inversion. Kinematic measurements were made at each stage using the same loads. Fusing the calcaneocuboid joint with lengthening or shortening the lateral column and the feet in neutral position did not affect hindfoot joint motion compared with intact. Changing the position of the foot for fusion, however, resulted in significant decreases in motion in the talocalcaneal and talonavicular joints. Tibiotalar joint motion was unaffected. This study, therefore, demonstrates that when fusing the calcaneocuboid joint, attention should be paid to maintaining a neutral position of the foot.

Guinea pig pulmonary mechanics: altered sensitivity to carbachol by cadmium and/or selenium.

Male Hartley guinea pigs (480-610 g) were treated intratracheally as follows: saline, cadmium (Cd, 0.3 mg), selenium (Se, 0.3 or 0.06 mg), or Se (0.06 mg) and Cd (0.3 mg) simultaneously. Selenium and Cd were administered as sodium selenite and cadmium chloride, respectively. Twenty-four h later, dynamic lung compliance (Cdyn) and pulmonary resistance (Rp) were measured before (baseline Cdyn and Rp) and after carbachol administration (0.0001, 0.001, 0.01, and 0.1 mumol/kg, intravenously). Results indicated a significant decrease in baseline Cdyn caused by 0.3 mg of Cd, 0.3 mg or 0.06 mg of Se, and 0.3 mg of Cd with 0.06 mg of Se (p < 0.05). A significant increase in baseline Rp due to 0.3 mg of Se was observed (p < 0.05). Carbachol decreased Cdyn significantly below baseline, evident after lower doses of carbachol, in guinea pigs pretreated with 0.3 mg of Se, whereas a significant improvement in Cdyn was seen after 0.0001 mumol/kg carbachol in the group pretreated with Se and Cd simultaneously (p < 0.05) compared with the respective baseline values of the saline-treated group. Similarly, a significant increase in Rp was observed after carbachol in groups pretreated with 0.3 mg of Cd or Se (p < 0.05). Results also indicated a significant increase in large airway constriction caused by Cd and/or Se (p < 0.05). A leftward shift in the carbachol dose-response curve indicated increased sensitivity to carbachol in Cd- and/or Sepretreated guinea pigs.

Cadmium and/or selenium effects on guinea pig lung PGE2, TXB2 and LTC4.

Male Hartley guinea pigs (480-610 g; n=5) were treated intratracheally with saline, cadmium (Cd, 0.3 mg) as cadmium chloride, selenium (Se, 0.3 or 0.06 mg) as sodium selenite or Se (0.06 mg) and Cd (0.3 mg). After 24 hours, lungs were collected and analyzed for prostaglandin (PGE2), thromboxane (TXB2) and leukotriene (LTC4) levels. Results indicated that, 0.3 mg Se and 0.06 mg Se in combination with 0.3 mg Cd increased PGE2 significantly. Selenium and Cd alone or in combination, decreased LTC4 and TXB2 significantly.