Toward imaging the dynamic interaction between actin and myosin using a wet-cell C-mode near-field optical microscope.

This paper describes the implementation of a wet-cell collection-mode near-field optical microscope that has been constructed with the long term goal of imaging the myosin conformational change as it interacts with actin. The bioassay used to prepare the samples involved lysing muscle fibers to exact and myosin molecules which were fixed to a mica slide. Next, actin filaments were exacted and deposited in the region of the myosin. The wet-cell allows the addition of water containing ATP and the necessary ions to activate the myosin biomolecules. The near-field optical microscope was shown to able to resolve features of the size of the actin and myosin biomolecules.

Implementation of a system using reflective tomographic reconstruction for breast cancer detection.

The following describes the implementation of a system for ultrasonic mammography. The system employs adaptive imaging and processing techniques to produce high-resolution breast tissues sonograms. The time-domain imaging technique provides quantitative maps of intrinsic acoustic tissue properties using conventional pulse-echo transducers and clinical scanning system. The increased image resolution and quantitative maps provide improve diagnostics tools compared with conventional B-scan images.

Traceability in cattle and small ruminants in Canada.

Traceback systems for cattle and small ruminants are of international concern after the outbreaks of bovine spongiform encephalopathy in the European Union and foot and mouth disease in the United Kingdom and South America. Implementation of a national or international identification system depends on meeting a balance between cost, reliability/durability, ease of use, data transfer speed, protection from fraud, avoidance of entry into the food chain and animal welfare issues. As of 1 January 2001, Canada has instituted a national identification programme for cattle, which will have annual operating and administrative costs of Can$0.20 per head, excluding ear tags. The system will provide herd of origin traceback and individual animal identification by ear tags for all beef cattle. A number of identification technologies are available that would have advantages over visual tags, but these are currently too costly without government support (electronic identification, deoxyribonucleic acid [DNA] fingerprinting), too slow (DNA fingerprinting) or have not been tested sufficiently (retinal imaging) to warrant mandatory inclusion in a national traceback/identification system.

The lung diffusing capacity for nitric oxide in rats is increased during endotoxemia.

Rats, when injected with endotoxin, begin to exhale nitric oxide (NO) within 1 h. This study measured the diffusing capacity for NO in the lungs of rats (DL(NO)) under both control and endotoxemic conditions, and it also estimated the rate at which endogenous NO (VP(NO)) enters the distal compartment of the lung, both in control rats and during endotoxemia. DL(NO) increased from 0.68 +/- 0.12 (SE) ml. min(-1). mmHg(-1) in control rats to 1.17 +/- 0.25 ml. min(-1). mmHg(-1) in endotoxemic rats. VP(NO) was 2.6 +/- 0.5 nl/min in control rats and attained a value of 218.6 +/- 50.1 nl/min at the height of NO exhalation 3 h after the endotoxin. We suggest that increased DL(NO) reflects an increase in pulmonary membrane diffusing capacity, caused by a pulmonary hypertension that is due to neutrophil aggregation in the lung capillaries. DL(NO) may also be increased by an enlarged pulmonary capillary volume because of the vasodilatory effects of the endogenous NO that is produced by the lung in response to the endotoxin. NO production by the lungs in response to endotoxin is unique in that it is the only situation reported to date in which pathologically induced increases in NO exhalation originate from the alveolar compartment of the lung, as opposed to the small conducting airways.

High dose rate brachytherapy in the treatment of cervical carcinoma.

Intracavitary brachytherapy has been shown to significantly reduce the rate of local recurrence in patients with cervix carcinoma. High dose rate (HDR) techniques use a high-intensity source to deliver high total doses of radiation over minutes, leading to the development of out-patient use of HDR brachytherapy procedures. HDR fractionation protocols that demonstrate rates of local control that are equivalent to low dose rate techniques and use smaller dose per fraction are recommended to decrease the probability of long-term complications with HDR.

Action potential classifiers: a functional comparison of template matching, principal components analysis and an artificial neural network.

Multiunit neural activity occurs often in electrophysiological studies when utilizing extracellular electrodes. In order to estimate the activity of the individual neurons each action potential in the recording must be classified to its neuron of origin. This paper compares the accuracy of two traditional methods of action potential classification--template matching and principal components--against the performance of an artificial neural network (ANN). Both traditional methods use averages of action potential shapes to form their corresponding classifiers while the artificial neural network 'learns' a nonlinear relationship between a set of prototype action potentials and assigned classes. The set of prototypic action potentials and the assigned classes is termed the training set. The training set contained action potentials from each class which exhibited the full range of amplitude variability. The ANN provided better classification results and was more robust in analysis of across-animal data sets than either of the traditional action potential classification methods.

Production and absorption of nitric oxide gas in the nose.

Some nitric oxide gas (NO) produced in the sinuses and nasal cavity is absorbed before leaving the nose. To measure production and absorption, we introduced NO at different concentrations into one nostril while sampling the NO leaving the opposite nostril with the soft palate closed. The quantity of NO gas produced in six normal subjects (amount leaving plus the amount absorbed) averaged 352 nl/min and was the same at gas flows ranging from 8 to 347 ml/min and at 10 l/min. An absorption coefficient A was calculated by dividing the amount of NO absorbed by the concentration leaving the nose. A ranged from 17 ml/min at a nasal gas flow of 8 ml/min to an A of 24 ml/min at a nasal gas flow of 347 ml/min. The calculated rates of production and absorption did not change when gas flow rate was increased, suggesting diffusion equilibrium. The amount of uptake of NO in the nasal mucosa can be explained by its solubility coupled with tissue and blood reactivity.

A system of tele-oncology at the University of Wisconsin Hospital and Clinics and regional oncology affiliate institutions.

Collaborative associations between academic medical centers and community hospitals can use telemedicine to promote and enhance cancer treatment and clinical research. It is expensive to duplicate communications technology at all sites, but it is possible to share technologies using telemedicine. This paper describes a system in evolution that provides regional oncology services at the University of Wisconsin Hospital and Clinics and regional oncology affiliates. The system requires integrated hardware and software to provide Internet access, videoconferencing, and data transmission. This system is comprised of several forms of technology that promote education and training, continuing medical education, patient evaluation and protocol eligibility, data transfer for radiation therapy treatment planning, and clinical and technologic quality assurance and peer review programs for medical oncology and radiation oncology.

The role of frozen section analysis of margins during breast conservation surgery.

PURPOSE: The role of frozen section analysis during breast conservation surgery is undefined. Assessment of margins using permanent section evaluation is the standard method of ensuring complete tumor excision. If the margin is positive, however, surgical re-excision is necessary to reduce the likelihood of subsequent local recurrence. Therefore, biopsy of the surgical cavity with immediate pathological evaluation during lumpectomy was performed to evaluate the effect on local recurrence, the number of re-excisions, and cosmesis. PATIENTS AND METHODS: One hundred sixty patients underwent attempted lumpectomy with frozen section margin determination. One hundred forty patients were available for long-term follow-up (mean = 57 months, median = 46 months). All patients underwent attempted breast conservation surgery, which consisted of tumorectomy with excision of a greater than 1-cm rim of grossly normal tissue. Tumor margins were obtained by intraoperative biopsy with frozen section analysis of the lumpectomy cavity walls. RESULTS: In 21 patients (15%), frozen section analyses (FSA) revealed positive margins, resulting in immediate re-excision. In seven of these patients (5%), margins were persistently positive, and these patients therefore underwent mastectomy. Fourteen patients were successfully re-excised to a negative margin. The sensitivity and specificity of FSA were 91% and 100%, respectively. Five percent of patients definitively managed by lumpectomy with FSA of margins recurred locally. The mean cosmesis score after radiotherapy was 7.0 out of a possible 10, correlating with a good to excellent result. DISCUSSION: The accuracy of FSA, low recurrence rate, avoidance of reoperation, and good cosmesis indicate that intraoperative frozen section analysis should be adopted as a safe and effective method of margin analysis during breast conservation surgery.

Code of practice for brachytherapy physics: report of the AAPM Radiation Therapy Committee Task Group No. 56. American Association of Physicists in Medicine.

Recommendations of the American Association of Physicists in Medicine (AAPM) for the practice of brachytherapy physics are presented. These guidelines were prepared by a task group of the AAPM Radiation Therapy Committee and have been reviewed and approved by the AAPM Science Council.

Exhalation of gaseous nitric oxide by rats in response to endotoxin and its absorption by the lungs.

Rats injected with a lipopolysaccharide endotoxin produce detectable concentrations of nitric oxide gas (NO) in the expired air within 60 min. The concentration of NO reaches a plateau at 3 h. Production of the NO is dose dependent on lipopolysaccharide, and at a dose of 1 mg/kg i.v., lipopolysaccharide alveolar concentrations of > 260 parts per billion are observed. NO synthase inhibitors suppress this NO production in response to endotoxin. Experiments were conducted to ascertain the site of origin of this NO and to measure the capacity of the lungs to absorb NO from alveolar air. Results indicate that the endotoxin-induced NO originates from within the lungs themselves and that the lungs have the capacity to absorb > 60% of NO that is presented to them. Lung tissues absorb approximately 44-47% of the NO load, blood carries away between 15 and 19%, while the remainder is exhaled in the expired air. It is proposed that the exhalation of NO might prove useful as an early biomarker for acute lung injury.

Innovations and advances in brachytherapy.

The treatment of cancer with radioactive sources using topical molds and intracavitary radium showed the efficacy of brachytherapy long before external radiation therapy became common practice. Brachytherapy is progressing in several clinical directions that reflect technological innovation as well as changes in medical care which combine to provide significant advances in the practice of brachytherapy today. A major change in brachytherapy, the development of high intensity sources, promoted clinical and technologic innovations in high dose-rate brachytherapy. Pulse dose-rate brachytherapy is the use of these sources to treat a target by using pulses of radiation for several minutes each hour with the same overall time and total dose as low dose-rate treatment. Recent novel approaches of using radiotherapy for prevention of restenosis in coronary and peripheral vessels has interested laboratory and clinical researchers. Most of the work toward new source material for brachytherapy centers around intravascular applications. Technology to support brachytherapy continues to advance rapidly. The interaction between images from diverse modalities and the various phases of the treatment planning is the basis of enhanced treatment planning procedures. Optimization in brachytherapy entails calculating the source strengths or source dwell times to satisfy a set of dose criteria to achieve the best dose distribution for a brachytherapy implant. Progress in computerization and calculation modeling has promoted this technical advance. Education and training in brachytherapy indications and techniques is mandatory to maintain high standards of brachytherapy practice.

Accidental hypothermia. When thermoregulation is overwhelmed.

The diagnosis of hypothermia must be entertained when patients present with unexplained mental status changes or arrhythmias. Prompt recognition and aggressive treatment of complications should reduce cold-related fatalities. The choice of an appropriate rewarming method must be individualized and depends on the severity of hypothermia and the patient's degree of hemodynamic tolerance.

Disorders of temperature regulation.

A remarkably effective and efficient thermoregulatory apparatus enables humans to maintain a normal body temperature despite widely varying and changing environmental and internal thermal conditions. Nevertheless, extreme ambient cold or heat and exhaustive exercise stress can overwhelm these defenses, leading to dangerous hypothermia or hyperthermia, respectively.

Laparoscopic lymph node dissection in the evaluation and management of patients with pelvic malignancy.

OBJECTIVE: This retrospective investigation describes our experience with laparoscopic pelvic and paraaortic lymph node dissection at a military medical center. METHODS: The charts of all patients undergoing laparoscopic pelvic and paraaortic lymph node dissection between July 1992 and May 1994 were reviewed for age, weight, cancer type, tumor stage, operative procedures, estimated blood loss, complications, number and pathologic results of lymph nodes removed, preoperative computed tomography findings, and postoperative therapy. RESULTS: The study group was composed of 20 patients, of which 15 had cervical cancer, 2 had ovarian cancer, and the rest had other pelvic malignancies. The mean age was 46 years old, with a mean weight of 155 pounds. The average number of lymph nodes removed was 26, with 9 of the 20 patients having positive nodes. Only one patient had preoperative radiographic evidence of lymphadenopathy. Mean estimated blood loss was 224 cc. Four patients required open procedures, two for bleeding during the laparoscopic node dissection and two who were unable to be completed through the laparoscope for technical reasons. Radical hysterectomy was avoided in two of the studied patients after finding positive lymph nodes. We conclude that in a military medical center, laparoscopic pelvic and paraaortic lymph node dissection in patients with certain pelvic malignancies is feasible and helps guide the management of these patients.

Heatstroke and other heat-related illnesses. The maladies of summer.

The spectrum of heat-related illnesses ranges from simple syncope to life-threatening heatstroke. Persons of all ages can be affected. Heat edema, heat cramps, heat syncope, and heat exhaustion respond readily to simple management techniques. Treatment of heatstroke must include aggressive cooling, adequate fluid and electrolyte repletion, maintenance of adequate cardiovascular performance, and prompt correction of any related or resulting complications.