Dynamics of picosecond laser ablation for surgical treatment of colorectal cancer.

Endoluminal surgery for the treatment of colorectal neoplasia is typically carried out using electrocautery tools which imply limited precision and the risk of harm through collateral thermal damage to the adjacent healthy tissue. As a potential alternative, we present the successful colonic epithelial laser ablation by means of picosecond laser pulses. Laser ablation studies performed in ex-vivo colon tissue result in cavities with comparable thickness to early stage colorectal cancers. The corresponding histology sections exhibit only minimal collateral damage to the surrounding tissue and the depth of the ablation can be controlled precisely by means of the pulse energy. High-speed imaging has been used for the first time to visualize picosecond laser ablation of cancerous tissue in a clinically relevant model. This information was correlated with histopathology and optical surface profilometry revealing the dynamic nature of the laser tissue interaction and the need for temporal or spatial separation of pulses for optimum efficacy with regards to tissue removal. Overall, the application of picosecond laser pulses to ablate endoluminal bowel lesions demonstrates significantly improved precision and reduced thermal damage to the adjacent tissue in comparison to conventional procedures and hence will enable more precise surgical treatment of cancers.

GenePath: a computer program for genetic pathway discovery from mutant data.

The sequencing of the human genome and the genomes of several model organisms is the first step toward the long-term objective of genetic research: the identification of all genes, and the discovery of their functions and mutual interactions. This article presents a methodology and a computer program called GenePath to support the discovery of gene function. GenePath uses mutant data and available genetic knowledge to identify potential genetic pathways. Several pilot applications based on experimental results from Dictyostelium and C. elegans confirmed the usefulness of the proposed schema. Our results suggest that GenePath is a valuable tool that can be used as an intelligent assistant to support genetic reasoning.

Comparison of tissue harmonic imaging with conventional US in abdominal disease.

Harmonic waves are generated from nonlinear distortion of an acoustic signal as an ultrasound wave insonates tissues in the body. These beams are integer multiples of a fundamental transmitted frequency. Potential advantages of harmonic imaging include improved axial resolution due to higher frequencies and better lateral resolution due to narrower beams. Decreased noise from side lobes improves signal-to-noise ratios and reduces artifacts. Deleterious effects of the body wall are also reduced. The authors prospectively studied ultrasonographic (US) findings in 100 adult patients with 202 abdominal lesions by comparing harmonic US images with conventional US images. The results were subjected to statistical analysis. Harmonic imaging was superior to conventional US in regard to lesion visibility and diagnostic confidence. Harmonic imaging was particularly useful for depicting cystic lesions and those containing echogenic tissues such as fat, calcium, or air. In patients with a body mass index of 30 or more, harmonic imaging was clearly better for lesion visibility and confidence of diagnosis. The authors recommend routine use of harmonic imaging for abdominal US studies in all adult patients.

The modified excimer laser-assisted high-flow bypass operation.

BACKGROUND: To make high-flow revascularization of the brain possible, we developed an anastomosis technique that obviates temporary occlusion of the recipient artery. After connecting donor and recipient vessels, an Excimer laser catheter, introduced by way of an artificial side branch, creates a hole at the anastomosis site. Because of the inconsistency of the diameter of the hole produced by the closed laser tip, we developed an extensive modification of the procedure. METHODS: A new type of laser tip was developed, consisting of two layers of 60 mu laser fibers in a circular configuration with a diameter of 2.2 mm. The laser tip is fixed to the vessel wall at the anastomosis site by suction with a high-vacuum suction device, and a round piece of recipient vessel wall inside the anastomosis is cut out. RESULTS: Using the aorta as the recipient vessel in 30 rabbits, the modified technique was developed and, in the end, produced anastomoses with a high patency rate. In 25 patients, high-flow bypasses for different indications were made using a venous transplant interposed between the external carotid artery or one of its branches and the intracranial internal carotid artery, utilizing the modified Excimer laser technique for the intracranial anastomosis. Complications related to the new anastomosis technique were minimal, and a satisfactory patency rate was obtained. CONCLUSIONS: The modified Excimer laser-assisted anastomosis technique makes high-flow revascularization of the brain a safe procedure, since temporary occlusion of the recipient proximal brain artery during the making of the anastomosis is obviated.

Frequency and outcome of infectious disease admissions to a pediatric intensive care unit.

This prospective clinical study was designed to assess patients with primary infectious disease (ID) necessitating admission to a pediatric intensive care unit (PICU), to identify morbidity and mortality risk factors, and to better define this subpopulation of critically ill children and compare them with patients who had a noninfectious disease (NID). All patients (N = 1,151) admitted to a multidisciplinary, university-affiliated, 20-bed PICU from January through December 1988 were studied. The patients were classified as having either ID or NID as the primary indication for PICU admission. Other variables assessed included age, sex, requirement for mechanical ventilatory support, and severity of illness at admission as determined by Pediatric Risk of Mortality (PRISM) score. Of the 1,151 patients admitted, 187 (16%) had ID. Patients with ID had significantly higher PRISM scores than NID patients, but mortality rates were not significantly different between the NID group (9%) and the ID group (11%). The ID and NID groups showed no significant difference with regard to sex, number of days in the ICU, or number of days of mechanical ventilatory support. Patients with ID were significantly younger than those without. Although the highest mortality overall was in neonates, there was no difference in mortality rate for this age group between ID and NID. Fifty-five (30%) of the 187 ID patients had a diagnosis of sepsis syndrome on admission, and had significantly higher PRISM scores and mortality than patients with other ID. We concluded that patients admitted to our PICU with a diagnosis of infectious disease were significantly younger and had higher severity of illness scores than patients admitted with a diagnosis of noninfectious disease. The most frequent cause of death in both groups was multisystem organ failure. Patients with sepsis syndrome showed showed no significant difference in overall mortality, but their PRISM scores and mortality rate were significantly greater than those of the other ID patients.

Cloning and analysis of MAGE-1-related genes.

The spectrum of MAGE gene expression in the human melanoma cell line DM150 was examined using reverse transcription polymerase chain reaction and cDNA cloning. We have isolated five full-length cDNAs from DM150 which were identified as MAGE-1, MAGE-3, MAGE-12 and two previously undescribed MAGE genes, MAGE-3b and MAGE-X2. DNA sequence analysis of the coding regions of the MAGE-3b and MAGE-X2 genes revealed 83% and 88% identity with MAGE-1, while MAGE-3b was 98% homologous with the full length MAGE-3 clone. The predicted amino acid sequences of MAGE-X2 and MAGE-3b contain consensus HLA-A1 peptide binding motifs, suggesting that, like MAGE-1, they may code for tumor-associated antigens. In addition, a nonamer peptide encoded by both the MAGE-3 and MAGE-12 genes was shown by direct binding studies to contain an aggretope for HLA-A2.

Microcomputer as patient educator.

A computer-assisted lesson on general drug knowledge as a patient education tool is described. A drug I.Q. quiz is one of seven microcomputer lessons available to patients in the waiting room of an ambulatory-care clinic. The drug quiz consists of 19 multiple-choice and six true or false questions. After each question, the computer responds with a brief paragraph keyed to the answer selected by the user. If the answer for a multiple-choice question is incorrect, the user can reanswer the question before proceeding. At the end of the lesson, a score is graphically displayed and the user is asked to evaluate the lesson. The computer stores the total number of lessons completed, total scores, number of times each question was answered incorrectly on first and second attempts, number of times each question was answered a second time, and each user's responses to the quiz and evaluation questions. Based on 313 completions of the drug quiz from September 1981 through May 1982, 86% of the users stated that they learned at least something useful, and 72% liked the quiz. The mean (+/- S.D.) number of correct answers on the first attempt was 16 +/- 5; scores improved by an average of 2.5 +/- 2 by reanswering questions. Of 2421 multiple-choice questions answered incorrectly, 62% were reanswered. Of these second attempts, 52% were correct. Item validity scores indicated that the drug quiz serves as a realistic appraisal of drug knowledge. The microcomputer can be an effective medium for patient education.

Changes in the gait patterns of growing children.

We observed the gait patterns, including time and distance measurements and ground reaction forces, of fifty-one normal children. Thirty-three children were retested once at one, three, six, nine, or twelve months, over a two-year period, for a total of eighty-four gait observations. Time and distance measurements and foot-ground reaction force measurements were found to be dependent on walking speed and the age of the child. An increase in height with age was found to be the major factor in determining the changes in time and distance measurements with age. For example, we found that average stride length was 76 per cent of the child's height at a walking speed of 1.04 meters per second regardless of the child's age. In contrast, the three components of foot-ground reaction force (vertical, lateral, and forward directions) were observed to vary with age up to five years even when normalized. After the age of five years an adult pattern of ground reaction force emerged. In addition, we found that walking patterns of children who were more than found years old did not vary when retested within a three-month period. However, for children less than four years old, measurements were found to change due to growth during the three-month period to retesting. Similar changes due to growth were found in children more than four years old who were tested at intervals more than three months apart. This important finding may be clinically useful in the study of the effects of treatment.

Effects of exercise and of food restriction on adipose tissue cellularity.

The body weight and fat content of young, growing rats were kept low by regularly performed endurance exercise by the rats or by restriction of their food intake over a period of 14 wk. The cellular character of epididymal fat pads was studied to determine if the reduction in fat was due to a decrease in the number of adipose cells, their size, or both. Compared with the sedentary freely eating control animals, both the exercisers and the sedentary paired-weight animals, which had their food intake restricted in order to maintain their body weights approximately the same as those of the exercisers, had significantly lighter epididymal fat pads (P < 0.001). This fat depot in the exercisers contained fewer (4.46 +/- 0.48 x 10(6) vs. 6.89 +/- 0.55 x 10(6) cells/pad; P < 0.001) and smaller (0.286 +/- 0.041 vs. 0.462 +/- 0.040 micro g of lipid/cell; P < 0.001) cells than that in the sedentary freely eating animals. Food restriction also resulted in a significant reduction in adipose tissue cellularity (P < 0.05). Epididymal fat pads from the calorie-restricted rats had an average of 5.72 +/- 0.33 x 10(6) cells and they contained 0.319 +/- 0.024 micro g of lipid/cell. These results demonstrate that exercise in addition to food restriction in early life is effective in reducing the rate of accumulation of cells in epididymal fat pads of rats.