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Biomedical subjects

R Rosen

Publications and source records attributed to R Rosen.

At least 55 records · Page 3Linked to original sources
PubMed1997

Multicenter trial of transscleral diode laser retinopexy in retinal detachment surgery.

PURPOSE: To evaluate the safety and efficacy of transscleral diode laser for retinopexy in rhegmatogenous retinal detachment surgery in a multicenter trial. DESIGN: 67 patients with primary rhegmatogenous retinal detachment underwent scleral buckling surgery, using transscleral diode laser for retinopexy, at five study centers. STUDY PARTICIPANTS: 72 patients with primary rhegmatogenous retinal detachments were enrolled. No patient with chronic detachment, a retinal break greater than 90 degrees, history of uveitis or infectious retinopathy, or proliferative vitreoretinopathy was enrolled. Five eyes were excluded because they required additional nonprotocol treatment at the time of surgery (vitrectomy or supplementary cryotherapy due to probe malfunction). MAIN OUTCOME MEASURES: Retinal reattachment at six months after one operation. Secondary measures: visual acuity and complications, including choroidal, retinal, and vitreous hemorrhage, inflammation, and scleral damage. RESULTS: Six months or greater follow-up information was available on 65 eyes. Retinas were attached at 6 months with a single operation in 58 (89%) of these eyes. Complications included apparent pinpoint breaks in Bruch is membrane in 15 eyes, scleral thermal effect in 14 eyes, and limited hemorrhage, which was intraretinal in 10 eyes, and extended into the vitreous in 3 eyes. In one case, hemorrhage was judged to have contributed possibly to initial surgical failure. The other complications had no known adverse effects. Complications were significantly associated with the physicians experience with transscleral laser retinopexy. CONCLUSION: In this multicenter series, transscleral diode laser retinopexy served as a safe and effective means of creating chorioretinal adhesion during retinal reattachment surgery. Minor complications were minimized by increasing experience with the technique.

Adolescent↗
PubMed1996

Imaging congenital optic disc pits and associated maculopathy using optical coherence tomography.

OBJECTIVE: To elucidate the anatomy of congenital optic disc pits with and without maculopathy using optical coherence tomography. SETTING: All patient were examined, photographed, and scanned at the New York Eye and Ear Infirmary. PATIENTS: Ten eyes of eight consecutive patients with congenital optic disc pits were studied. Three eyes had associated serous macular detachment (group 1), four had evidence of resolved detachment (group 2), and three had no clinical macular pathologic lesion (group 3). METHODS: Optical coherence tomography, a new, noninvasive, noncontact, imaging technology capable of producing cross-sectional images of the retina in vivo with high resolution ( < 17 microns) was used to obtain multiple cross-sectional images of the pit, peripapillary retina, and macula. Ophthalmologic examination and standard fundus photography were performed on all eyes. Fluorescein angiography was performed in eyes that had associated macular detachment. RESULTS: Communication between a schisis cavity or subretinal space and the optic nerve pit was imaged in all eyes in group 1. No such communication could be identified in groups 2 and 3. Cystic degeneration and schisis were imaged in the peripapillary retina, macula, or both in all eyes of groups 1 and 2 and in one patient in group 3. A direct communication between the subretinal space and vitreous cavity could not be identified in any eye. CONCLUSIONS: Schisis formation plays an integral role in the development of serous retinal detachment in the presence of congenital optic disc pits. Our findings are consistent with the theory that the optic disc pit acts as a conduit for fluid flow between the schisis cavity or subretinal space and the subarachnoid space.

Adult↗
PubMed1996

Biology and the measurement problem.

Present-day molecular biology, despite its name, is almost entirely committed to a macroscopic, classical picture of the organism; one in which quantum aspects play no role, except as a source of noise. Particularly is this true when dealing with informational aspects; especially "genetic information". The pervading metaphor here is an identification of "genetic information" with DNA sequence, and thence with program or software. We take a quite different view herein. If we presume, to the contrary, that microphysical processes play a role in primary genetic processes, then the "information" they can convey consists of observables evaluated on states. It is then natural to analogize a complex, consisting of (observed system + observer) with the biological partition between genome (observed system) and phenotype (observer). Such a picture immediately raises the deep issues surrounding "the measurement problem" in quantum mechanics. In our brief consideration of such matters, we suggest that standard quantum mechanics is too narrow to deal with the biological pictures, because it is inexorably tied to quantifications of classical, conservative systems; there is no such for an organism. Rather, we are led to consider subsystems we call "sites", for which there is in principle no Hamiltonian. We then query the extent to which such "genetic information" is already subsumed in traditional observables a physicist would measure in vitro in a laboratory. We suggest there is no reason to believe that "genetic information", manifested in bioactivities, is reducible to these. Finally, we contrast this view of "genetic information" with more traditional ideas of program and computability. We argue that computability (algorithms) are entirely classical concepts, in a physical sense, and quite inadequate for a biology (or even a physics) in which quantum measurement processes are important.

Computational Biology↗
PubMed1996

Deep venous thrombosis with pulmonary embolus after selective embolization of an internal iliac artery aneurysm.

A 69-year-old man with an isolated right internal iliac artery aneurysm measuring 5.6 cm in diameter was treated with percutaneous embolization inducing thrombosis of the aneurysm. Four months later, he was seen with thrombosis of the right common iliac vein and pulmonary embolus. He subsequently underwent ligation of the aneurysm and repair of the right common iliac artery. Computed tomographic and operative findings suggested that the iliac vein thrombosis was the result of direct compression by the aneurysm itself, as well as perianeurysmal inflammation that encased the right common iliac vein. This report summarizes this case and presents a new potential long-term complication after successful selective embolization of an internal iliac artery aneurysm.

Aged↗
PubMed1995

VLA-4 and its ligands: relevance to kidney diseases.

Alterations in cellular immunity have been implicated in many kidney diseases. The role of the adhesion molecule VLA-4 and its known ligands VCAM-1 and CS-1 have just begun to be evaluated in association with kidney diseases. VCAM-1 in human kidney is normally expressed in the Bowman's capsule, in the proximal renal tubule, and in the vascular endothelium. Up-regulation of VCAM-1 expression is seen in many different forms of glomerulonephritis as well as in a mouse model of lupus nephritis. Up-regulation of VCAM-1 expression is observed in the renal allograft with acute cellular rejection, and correlates with areas of leukocyte infiltration and vascular inflammation. CS-1 may also be up-regulated in the rejecting kidney. Animal studies on cardiac transplantation demonstrate that blockade of VLA-4 or VCAM-1 can attenuate transplant rejection. Hemodialysis patients, known to have a cellular immunodeficiency, have increased levels of soluble VCAM-1 in their serum. There is increasing evidence that there are alterations in VLA-4, VCAM-1 and CS-1 in association with kidney diseases. Further studies will be required to delineate the role of these molecules in the immunopathogenesis of select kidney diseases and the possibility of intervening in these adhesion pathways to ameliorate clinical syndromes.

Animals↗
PubMed1994

Serum 17-beta-estradiol and testosterone levels in asymptomatic hyperuricaemic men.

Low levels of oestrogen, FSH and LH in serum have been reported in patients with gout. The mechanism by which sex hormones affect the development of gout is unknown, but some investigators believe that it is related to the influence of oestrogens on serum uric acid levels. We studied the relationship between serum uric acid and 17 beta oestradiol (ES) levels in asymptomatic hyperuricaemic (ASH) men in order to test the hypothesis that low ES levels are associated with hyperuricaemia. Thirty-eight men with asymptomatic hyperuricaemia (ASH) were selected from a population of healthy individuals undergoing periodical multiphasic health examinations. After adjusting for the differences in albumin levels between the two groups, no significant difference in serum ES level was found. The serum testosterone levels were similar in both groups. These findings suggest that there is no difference in the sex hormone profiles between asymptomatic hyperuricaemic and normouricaemic men.

Adult↗
PubMed1994

What is biology?

The following work compares two different ways of fractionating or abstracting from an organism: (a) a Mendelian way, which views the organism as a discrete bundle of phenotypic characters, each controlled by a corresponding genetic "factor", and (b) as a bundle of particulate molecular fractions, as envisaged by molecular biology. It is generally believed that the latter completely subsumes the former, and that it further serves to subsume all of biology into contemporary physics. We argue herein that the first of these assertions, if true at all, does not follow from an initial positing of an identity between the Mendelian gene and DNA sequence, and may well be false in general. In either case, the second assertion becomes false as well. This has profound consequences, not only for biology, but for the physics which is presumed to underlie it; it constitutes a part of the "new physics" which Erwin Schrôdinger, in a famous essay [(1944) What is Life? Cambridge University Press, Cambridge], argued was inherent in biology.

Biology↗
PubMed1994

The rapid development of the glucose transport system in the excysted metacestode of Hymenolepis diminuta.

Temporal changes in glucose transport capacity in excysted scoleces of Hymenolepis diminuta were examined. Assays involved incubation for 1 min in [3H]glucose after pre-incubation for 1 min to 8 h in saline. There were two abrupt increases in uptake velocity, a relatively small one between 15 and 75 min, and a large one between 5 and 6 h, during which the Vmax increased from 0.36 to 2.49 nmol/25 larvae/h. The second increase was unaffected when the pre-incubation saline contained 5 mM glucose, but it was completely blocked when the excysted larvae were pre-incubated in Ca(2+)-free saline. Abrupt glucose transport changes did not occur in intact cysticercoids or in scoleces when the substrate was [3H]leucine or [3H]uracil. Arrhenius plots (log V versus 1/temperature, 10-42 degrees C) were linear for intact cysticercoids, but were biphasic for both scoleces and adults with discontinuities at 20 +/- 1 degrees C. Thus, 'activation' of the excysted scolex seemed to involve a specific, Ca(2+)-dependent increase in number of glucose transporters functioning in the worm surface. The Arrhenius plots indicated that development in the final host does not involve a major change in lipid composition of the parasite's membranes.

Animals↗
PubMed1993

Drawing the boundary between subject and object: comments on the mind-brain problem.

Physics says that it cannot deal with the mind-brain problem, because it does not deal in subjectivities, and mind is subjective. However, biologists (among others) still claim to seek a material basis for subjective mental processes, which would thereby render them objective. Something is clearly wrong here. I claim that what is wrong is the adoption of too narrow a view of what constitutes 'objectivity', especially in identifying it with what a 'machine' can do. I approach the problem in the light of two cognate circumstances: (a) the 'measurement problem' in quantum physics, and (b) the objectivity of standard mathematics, even though most of it is beyond the reach of 'machines'. I argue that the only resolution to such problems is in the recognition that closed loops of causation are 'objective'; i.e. legitimate objects of scientific scrutiny. These are explicitly forbidden in any machine or mechanism. A material system which contains such loops is called 'complex'. Such complex systems thus must possess non-simulable models; i.e. models which contain impredicativities or 'self-references' which cannot be removed, or faithfully mapped into a single coherent syntactic time-frame. I consider a few of the consequences of the above, in the context of thus redrawing the boundary between subject and object.

Biophysical Phenomena↗
PubMed1993

Dermal myiasis in an Australian traveller.

Myiasis, the infestation of body tissues by the larvae of flies, occurs infrequently in Australian tourists who return from areas where certain species are endemic. Some of these insect species such as Cochliomyia hominivorax and Chrysoma bezziana (New and Old World screw-worms respectively) are responsible for significant disease in livestock as well as in humans. We report a patient who travelled extensively through South America and returned to Australia with a subcutaneous nodule containing a large larva of the species Dermatobia hominis. Because of the risk of travellers introducing unwanted species of flies into our country, it is important for doctors to suspect the possibility of furuncular myiasis, and to obtain accurate identification of the larva.

Adult↗
PubMed1993

Generalised granuloma annulare successfully treated with pentoxifylline.

Generalised granuloma annulare (GA) is a chronic disease of unknown aetiology and is recalcitrant to many treatment regimes. Some investigators have suggested that an immune medicated vasculitis may be involved in the pathogenesis of GA. We describe a patient with a ten year history of generalised GA, who showed dramatic clearing of the majority of papules after four weeks of treatment with pentoxifylline. This drug has shown promising results in the treatment of many dermatologic disorders including necrobiosis lipoidica diabeticorum, leukocytoclastic vasculitis and Raynaud's phenomenon. Pentoxifylline is thought to reduce blood viscosity via effects on all major blood components, and its clinical effectiveness in generalised GA lends support to a model of immune-medicated vasculitis in the pathogenesis of this disorder. Thus, pentoxifylline offers a well-tolerated and effective alternative to the treatment options available for patients with granuloma annulare.

Blood Viscosity↗
PubMed1992

Cutaneous Bowen's disease. An analysis of 1001 cases according to age, sex, and site.

BACKGROUND: There are no large studies of Bowen's disease that have analyzed its distribution according to age, sex, and site. OBJECTIVE: This study was performed primarily to determine whether there were significant sex and site differences in the distribution of Bowen's disease. METHODS: One thousand one skin biopsy specimens of Bowen's disease were analyzed according to age, sex, and site of origin. RESULTS: This study revealed that the most common site of Bowen's disease was the head and neck (440 lesions), whereas specimens from the lower limbs (298 lesions) and upper limbs (198 lesions) outnumbered specimens from the torso (65 lesions). Of 298 specimens from the lower limbs, 72.1% were from women; 79.3% of the 87 specimens from the scalp and ears were from men. Eighty percent of the 85 specimens of Bowen's disease from the cheeks were from women. CONCLUSION: These results indicate that cutaneous Bowen's disease occurs mainly on sun-exposed sites. This is also supported by the predominance of Bowen's disease on the lower limbs in women and on the scalp and ears in men. The basis for the female predominance on the cheeks is unknown, but may reflect the increased vulnerability to sun damage of superficial vellus hair follicles that predominate on the cheeks in women. This finding may provide indirect support for the hypothesis that some forms of Bowen's disease have a follicular histogenesis.

Adult↗
PubMed1990

Halo eczema surrounding seborrhoeic keratoses: an example of perilesional nummular dermatitis.

Two patients developed halo eczema around isolated seborrhoeic keratoses and in one individual similar halo eczema developed around the nipples. This phenomenon which was previously described with melanocytic naevi has been associated with a number of different central lesions and can be readily recognised. Both the clinical pattern and histopathology suggest that this phenomenon may represent a localised form of nummular dermatitis with a predilection for elevated lesions.

Adult↗
PubMed1988

Hemoglobin Pasadena: identification of the gene mutant by DNA analysis using synthetic DNA probes.

Hemoglobin Pasadena [beta 75(E19)Leu----Arg] was found in a boy who had an acute episode of anemia and rapid splenic enlargement. His father was the only other member of a large family with this hemoglobinopathy. We have used gene mapping techniques for direct identification of the beta-globin gene mutation. To correlate the DNA findings with the structural identification of this variant, we have also performed globin chain separation and analysis of the tryptic peptides using high performance liquid chromatography and secondary ion mass spectral analysis.

Adult↗
PubMed1987

Videofluoroscopic and scintigraphic analysis of dysphagia in the head and neck cancer patient.

This paper presents two advances in the evaluation of swallowing function which better define the swallowing processes in the head and neck cancer patient. Videofluoroscopy, improved by computer-assisted image analysis, provides more accurate information regarding oral and pharyngeal movement of structures. Radionuclide scintigraphy, a complementary technique, quantitates bolus flow (transit times) and the degree of aspiration. Several cases demonstrate the advantages of the methods and their usefulness in evaluating the effects of cancer treatment. The improved techniques also provide opportunity for designing new strategies of medical and surgical rehabilitation.

Adult↗
PubMed1987

Detection and quantification of laryngotracheopulmonary aspiration with scintigraphy.

Aspiration is analyzed by a new scintigraphic technique and standard videofluoroscopy in 78 patients with head and neck pathology and neurologic disorders. When both methods are compared to clinical aspiration and a positive x-ray film of pneumonia, they appear to complement each other and provide a very accurate evaluation. Scintigraphy is a more sensitive method for detecting aspiration below the vocal cords and also provides for flow dynamics and a method of quantifying the amount of aspirated material. Videofluoroscopy shows more clearly the mechanism of the swallowing disorder and how the bolus enters the tracheobronchial tree. Studies in patients following head and neck surgery demonstrate a high incidence of dysphagia, aspiration, and pneumonia.

Deglutition↗