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Biomedical subjects

I Rabin

Publications and source records attributed to I Rabin.

8 recordsLinked to original sources
PubMed2005

Anal melanoma in the era of sentinel lymph node mapping: a diagnostic and therapeutic challenge.

Melanoma of the anal canal is a rare malignancy that often has an atypical presentation. Locoregional metastases, which are often present at the initial presentation, may occur in both groin and pelvic lymph nodes, but the utility of lymph node dissection remains unknown. We explored the possibility of applying the technique of sentinel lymph node (SLN) mapping to anal melanoma. SLN mapping was performed in 2 patients with anal melanoma. Radioactive tracer and blue dye were injected around the lesions. The SLN was identified pre-operatively by lymphoscintigraphy, and at surgery with a hand-held gamma detector and by visualization of the dye. The SLN was identified in both patients, only in the groin in one and only in the presacral region in the other. One patient had a wide local excision of the anal lesion with house flap anoplasty, while the other had abdominoperineal resection with total mesorectal excision. There were no SLN metastases in either patient. The technique of SLN mapping and biopsy is easily adapted to surgery for malignant melanoma of the anus. SLN mapping and biopsy could aid in planning surgical strategy, but definitive conclusions may only be reached after more experience has been acquired.

Anus Neoplasms↗
PubMed2001

Ag8 fluorescence in argon.

The fluorescence of Ag8 in an argon matrix and in argon droplets is reported. This is the first unambiguous assignment of the fluorescence of a metal cluster larger than the tetramer, indicating that the excited state lifetime is longer than previously thought. It is discussed as a possible result of a matrix cage effect. The excitation spectrum is compared with two-photon-ionization measurements of Ag8 in helium droplets and to known absorption data. The agreement is excellent. We propose that the excited states relax rapidly through vibrational coupling to a long-lived state, from which the fluorescence occurs.

Journal Article↗
PubMed1998

Near-field optical imaging of unstained bacteria: comparison with normal atomic force and far-field optical microscopy in air and aqueous media.

Simultaneous near-field scanning optical and atomic force imaging of bacteria is presented. The bacteria imaged in these studies were unstained. The near-field optical images had excellent signal-to-noise and showed excellent contrast even in these unstained specimens. The images obtained were interpreted in terms of the images that have been obtained by transmission electron microscopy and X-ray imaging. The results show that bacterial near-field optical imaging is going to be a very important tool in the arsenal of the bacteriologist both in terms of understanding the fundamental processes in the life cycle of bacteria with and without cytochemical staining and in terms of clinical diagnostic applications.

Bacillus megaterium↗
PubMed1996

Chemiluminescence in the Agglomeration of Metal Clusters

The agglomeration of copper or silver atoms in a matrix of noble gas atoms to form small clusters may be accompanied by the emission of visible light. Spectral analysis reveals the intermediate formation of electronically excited atoms and dimers as the source of the chemiluminescence. A mechanism is proposed, according to which the gain in binding energy upon cluster formation may even lead to the ejection of excited fragments as a result of unstable intermediate configurations. A similar concept was introduced in the field of nuclear reactions by Niels Bohr 60 years ago.

Journal Article↗
PubMed1995

Sudden death as a result of heart disease in morbid obesity.

Patients with morbid obesity have high rates of sudden, unexpected cardiac death. The mechanism of death in these patients is uncertain. Twenty-eight patients with morbid obesity (22 sudden cardiac deaths, 6 unnatural deaths) were compared to 11 age-matched nonobese patients with traumatic deaths. Heart weight, left ventricular cavity diameter, left and right ventricular wall thickness, ventricular septal thickness, epicardial fat thickness, and extent of coronary artery atherosclerosis were determined; myocyte size, nuclear size, and degree of interstitial fibrosis were calculated morphometrically. Mean heart weights in the patients with morbid obesity were increased but remained constant as a percentage of body weight. Of the gross parameters, only heart weight and left ventricular cavity size were independent predictors of obesity. Of microscopic parameters, only nuclear area was an independent predictor of obesity. Of 22 patients with morbid obesity, dilated cardiomyopathy was the most frequent cause of sudden cardiac death in (10 patients), followed by severe coronary atherosclerosis (6), concentric left ventricular hypertrophy without left ventricular dilatation (4), pulmonary embolism (1), and hypoplastic coronary arteries (1). The cardiomyopathy of morbid obesity is characterized by cardiomegaly, left ventricular dilatation, and myocyte hypertrophy in the absence of interstitial fibrosis. It is the most common cause of sudden cardiac death in these patients.

Adult↗
PubMedDate not supplied

[Self-similarity in the structure of DNA: why are introns needed?].

Consequences of the hypothesis are analyzed that native spatial structure of DNA is the so-called crumpled globule, which is statistically free of knots. Since crumpled globule is self-similar fractal object in space, fixation of more or less unique chain fold, that is the case for eukaryotes, requires some self-similarity of the sequence. On this basis we explain quantitatively long-range power-law correlations in intron containing genes which have been discovered recently, predict some more detailed properties of correlations, which partly convinced already in experiment, and formulate a few more general hypotheses on the statistical properties of presently unassigned parts of DNA, on the role of intron as the instrument of fixation of DNA spatial structure and on the possible way of creation of such an apparatus in the evolution.

DNA↗