Mimicking muscle fiber structure and function through electromechanical actuation of electrospun silk fiber bundles.

Here we detail the fabrication and testing of artificial muscles fabricated from composites of the natural biopolymer silk fibroin and conducting polymers. Aligned nanofiber bundles of silk that mimic the structure of skeletal muscles were produced via electrospinning, and the fibers were infused with conducting polymers using chemical and electrochemical in situ polymerization methods. The resulting bundles of individual, electroactive fibers underwent electromechanical actuation in biologically-relevant electrolyte solutions when low potentials were applied, thus mimicking the contractile function of native muscles. The fabrication methods, bulk mechanical properties, stress and strain generation, and stability under repeated actuation for fiber bundles coated with different conducting polymer formulations are presented.

Occurrence of antibiotic-resistant bacteria and endotoxin associated with the land application of biosolids.

The purpose of this study was to determine the prevalence of antibiotic-resistant bacteria and endotoxin in soil after land application of biosolids. Soil was collected over a 15 month period following land application of biosolids, and antibiotic resistance was ascertained using clinically relevant antibiotic concentrations. Ampicillin, cephalothin, ciprofloxacin, and tetracycline resistance were all monitored separately for any changes throughout the 15 month period. Endotoxin soil concentrations were monitored using commercially available endotoxin analysis reagents. Overall, land application of biosolids did not increase the percentage of antibiotic-resistant culturable bacteria above background soil levels. Likewise, land application of biosolids did not significantly increase the concentration of endotoxin in soil. This study determined and established a baseline understanding of the overall effect that land application of biosolids had on the land-applied field with respect to antibiotic-resistant bacterial and endotoxin soil densities.

Arthrodiastasis in Perthes' disease. Preliminary results.

We have examined the effect of arthrodiastasis on the preservation of the femoral head in older children with Perthes' disease. We carried out a prospective trial in boys over the age of eight years and girls over seven years at the time of the onset of symptoms. The patients had minimal epiphyseal collapse and were compared with a conventionally treated, consecutive, historical control group. Arthrodiastasis was applied for approximately four months. The primary outcome measure was the extent of epiphyseal collapse at the end of the fragmentation phase. One of the 15 treated hips and nine of the 30 control hips showed a loss of height of 50% or more of the lateral epiphyseal column on the anteroposterior radiographs (Herring grade-C classification). On a Lauenstein view, one of the treated hips and 19 of the control hips showed at least a loss of height of 50% of the anterior epiphyseal column. The complications of arthrodiastasis included pin-site infection in most hips, transient joint stiffness in two, and breakage of a pin in two. The final outcome will be known when all the patients and the control group reach skeletal maturity.

Clinical screening for developmental dysplasia of the hip in Northern Ireland.

PROBLEM: The incidence of late diagnosed developmental dysplasia of the hip requiring surgery in Northern Ireland is high. The reported incidence was 1.14 per 1000 children born during 1983-7. DESIGN: Comparative retrospective study. BACKGROUND AND SETTING: Clinical screening programme in Northern Ireland. Key measure for improvement: Reduced rate of operative intervention in children with developmental dysplasia of the hip detected after 6 months of age. STRATEGIES FOR CHANGE: Increased emphasis on staff training, introduction of a centralised nurse led clinic to improve access to orthopaedic surgeons, and increased use of ultrasonography. EFFECTS OF CHANGE: The incidence of developmental dysplasia of the hip diagnosed after 6 months in children born between January 1991 and December 1997 fell to 0.59 per 1000, presumably due to improved early detection. Nevertheless, 29 (16%) of the affected hips were not diagnosed when the child was first referred in the first 3 months of life. In addition, for 27 affected hips in children diagnosed after the age of 6 months there was a known risk factor (family history or breech delivery). LESSONS LEARNT: Improvements to screening processes can reduce late incidence of developmental dysplasia of the hip. Further steps to improve detection in children with known risk factors and rate of detection at first referral could reduce late presentation further.

Quantitative aspiration during sleep in normal subjects.

STUDY OBJECTIVE: To determine the within-subject variability and to estimate the quantity of occult aspiration of nasopharyngeal secretions during sleep in normal humans. DESIGN: Prospective duplicate full-night sleep studies. SETTING: Pulmonary sleep laboratory, university hospital. PARTICIPANTS: Ten normal male volunteers aged 22 to 55 years. INTERVENTIONS: Two full-night polysomnographic recordings with infusion of 2 mL/h radioactive 99mTc tracer into the nasopharynx through a small catheter during EEG-documented sleep. Standard lung scans were conducted immediately following final awakening. Aspiration was defined as the presence of radioactivity in the pulmonary parenchyma on two separate views. RESULTS: A mean sleep efficiency of 85.7 +/- 2.6% was found with no difference between the two study nights. A total of 5 of the 10 subjects studied had tracer evident in the pulmonary parenchyma following final awakening. Three had the tracer apparent following the first-night study and four had tracer apparent following the second-night study. Thus, two subjects aspirated on both nights. Comparing the subjects who aspirated with those who did not, no significant difference could be found for age, time spent in bed, sleep efficiency, apnea-hypopnea index, arousal plus awakening index, or percent of sleep time spent in a supine position. The quantities of tracer aspirated were on the order of magnitude of 0.01 to 0.2 mL. CONCLUSIONS: Aspiration measured by this technique occurs commonly in healthy young men during sleep, is unrelated to sleep quality, and is variable within subjects studied on more than one occasion. The quantity aspirated is of an order of magnitude likely to contain bacterial organisms in physiologically significant quantities.

Risk-adjusted Medicare capitation rates using ambulatory and inpatient diagnoses.

Researchers at The Johns Hopkins University (JHU) developed two new diagnosis-oriented methodologies for setting risk adjusted capitation rates for managed care plans contracting with Medicare. These adjusters predict the future medical expenditures of aged Medicare enrollees based on demographic factors and diagnostic information. The models use the Ambulatory Care Group (ACG) algorithm to categorize ambulatory diagnoses. Two alternative approaches for categorizing inpatient diagnoses were used. Lewin-VHI, Inc. evaluated the models using data from 624,000 randomly selected aged Medicare beneficiaries. The models predict expenditures far better than the Adjusted Average per Capita Cost (AAPCC) payment method. It is possible that risk adjusted capitation payments could encourage health plans to compete on the basis of efficiency and quality and not risk selection.

Is an anticholinergic agent superior to a beta 2-agonist in improving dyspnea and exercise limitation in COPD?

STUDY OBJECTIVE: To evaluate the impact of a week-long course of inhaled albuterol compared with ipratropium on expiratory peak flow, exercise performance, and dyspnea in patients with stable COPD. DESIGN AND INTERVENTIONS: A double-blind, two-period, crossover evaluation, wherein the subjects inhaled albuterol, two puffs four times a day (qid) for 7 days, or ipratropium, two puffs quid for 7 days, in random sequence. SETTING: Outpatients of the Pennsylvania State University Hospital, Lebanon VA Medical Center, and local private office practices. PARTICIPANTS: A sample of 15 subjects with stable COPD with FEV1 < 55% predicted. MEASUREMENTS AND RESULTS: Variables measured at baseline (no inhaled bronchodilator) and/or on day 7 of each arm included FEV1 (liters), 12-min walk test distance (meters), "rescue" puffs of metaproterenol needed each week, and dyspnea scoring after walking, on the Borg Category Scale (0 to 10 = maximal). There was no significant difference in distance walked in 12 min (mean of 751.0 +/- 55.5 [+/- SE]) vs 755.7 +/- 61.3 m) or perceived dyspnea (mean 2.7 +/- 0.4 vs 3.3 +/- 0.4) during albuterol or ipratropium use. Seven patients preferred ipratropium, seven preferred albuterol, and one had no preference. CONCLUSION: We conclude that the effects of 1 week of albuterol or ipratropium have similar effects on exercise performance and subjective dyspnea in patients with stable COPD.

Acquired immunodeficiency syndrome and Pneumocystis carinii infection in a pregnant woman.

Human immunodeficiency virus (HIV) infections are being seen with greater regularity by the obstetrician-gynecologist. Acquired immunodeficiency syndrome (AIDS), the extreme of the spectrum of HIV infections, is associated with Pneumocystis carinii infection in more than half of newly diagnosed cases. Four cases of AIDS and P carinii pneumonia complicating pregnancy have been reported in the literature, and all have caused maternal death. We report a case in which the mother survived. Treatment was similar to that used in the other reported cases except that steroids were added. A limited number of patients with AIDS and P carinii infection have been treated with trimethopterim-sulfamethoxazole and steroids, with good results. Steroids should be considered for cases in which other efforts are failing.

Management of advanced endodermal sinus tumor of the ovary with preservation of reproductive function.

Endodermal sinus tumor of the ovary occurs primarily in children and young adults. This tumor is classified as a germ cell tumor which comprises approximately 5% of all ovarian tumors. In the past, patients with this highly malignant tumor had low survival. However, with the evolution of effective adjunctive chemotherapeutic regimens, specifically vincristine, actinomycin D, and cyclophosphamide, survival rates have improved. In an attempt to continuously improve survival rates, other combination chemotherapeutic regimens are currently under investigation. Unlike epithelial ovarian malignancies, endodermal sinus tumor can be monitored by a specific tumor marker, alpha-fetoprotein (AFP). Serum levels of AFP can be followed from the preoperative period through the course of chemotherapy. When elevated, AFP has excellent predictability that persistent disease is present. Because this disease presents primarily in young females, preservation of reproductive function is of utmost importance. We report a case of advanced endodermal sinus tumor which was managed with conservative surgery only, followed by radical combination chemotherapy, resulting in preservation of normal reproductive function and total resolution of disease documented by second-look laparotomy.

Correlation of operative findings with angiographic and noninvasive hemodynamic factors associated with failure of polytetrafluoroethylene grafts.

The causes of autogenous saphenous vein (ASV) graft failure have been well described and are predominantly due to stenosis of the ASV graft during the first year after implantation. Distal atherosclerotic disease is a late cause of ASV graft failure. Furthermore, with failure of the ASV graft the clinical and hemodynamic status of the limb usually reverts to the preoperative state. To better define the causes and hemodynamic consequences of polytetrafluoroethylene (PTFE) graft failure, we reviewed the pathologic findings at surgery and compared these with arteriograms made prior to and after occlusion and sequential noninvasive hemodynamic studies in 36 patients with failed PTFE grafts (greater than 30 days after operation). Distal atherosclerotic disease was the most frequent cause of PTFE failure (23 of 36 limbs, or 64%), and it appeared as early as the first 6 months after implantation. Doppler pressures after PTFE failure deteriorated significantly (p less than 0.05) at the thigh, calf, and ankle levels. A blinded comparison of preoperative with postoperative arteriograms revealed significant progression of disease. Because of significant involvement of the popliteal artery in our series, treatment of intimal hyperplasia with patch angioplasty (seven cases, or 19%) was short lived and sequential extension was required. Distal atherosclerotic disease therefore appeared to be the most common cause of PTFE graft failure and occurred much earlier after implantation than with ASV graft failure. Deterioration of the hemodynamic state of the limb correlated with this high degree of distal atherosclerotic disease.

Translumbar carotid arteriography.

In seven patients, carotid arteriography and arch aortography were performed using a translumbar catheter exchange sheath which facilitated selective catheterization. No significant complications occurred. The translumbar approach is easier than the axillary approach, will result in fewer complications, and should be considered whenever a femoral arterial access is unavailable.

Translumbar coronary arteriography.

Selective coronary angiography, using a catheter sheath placed across the lumbar region and into the abdominal aorta, has been performed for a patient with lack of other arterial access due to severe occlusive atherosclerosis in the abdominal aorta and innominate and left subclavian arteries. This approach is quick and facile, but care must be taken to prevent possible bleeding complications.