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Biomedical subjects

E Sacks

Publications and source records attributed to E Sacks.

14 recordsLinked to original sources
PubMed2003

Convergent evolution of perenniality in rice and sorghum.

Annual and perennial habit are two major strategies by which grasses adapt to seasonal environmental change, and these distinguish cultivated cereals from their wild relatives. Rhizomatousness, a key trait contributing to perenniality, was investigated by using an F(2) population from a cross between cultivated rice (Oryza sativa) and its wild relative, Oryza longistaminata. Molecular mapping based on a complete simple sequence-repeat map revealed two dominant-complementary genes controlling rhizomatousness. Rhz3 was mapped to the interval between markers OSR16 [1.3 centimorgans (cM)] and OSR13 (8.1 cM) on rice chromosome 4 and Rhz2 located between RM119 (2.2 cM) and RM273 (7.4 cM) on chromosome 3. Comparative mapping indicated that each gene closely corresponds to major quantitative trait loci (QTLs) controlling rhizomatousness in Sorghum propinquum, a wild relative of cultivated sorghum. Correspondence of these genes in rice and sorghum, which diverged from a common ancestor approximately 50 million years ago, suggests that the two genes may be key regulators of rhizome development in many Poaceae. Many additional QTLs affecting abundance of rhizomes in O. longistaminata were identified, most of which also corresponded to the locations of S. propinquum QTLs. Convergent evolution of independent mutations at, in some cases, corresponding genes may have been responsible for the evolution of annual cereals from perennial wild grasses. DNA markers closely linked to Rhz2 and Rhz3 will facilitate cloning of the genes, which may contribute significantly to our understanding of grass evolution, advance opportunities to develop perennial cereals, and offer insights into environmentally benign weed-control strategies.

Biological Evolution↗
PubMed1996

Radiation therapy of metastatic pheochromocytoma: case report and review of the literature.

Malignant pheochromocytomas are rare tumors, which are considered radioresistant on the basis of little information. We report a patient, with cranial nerve deficits from a pheochromocytoma metastatic to the parasellar region, who promptly responded to radiation therapy (2,500 cGy) with reversal of neurologic deficit. The disease recurred 2 years later and again promptly responded upon treatment to 2,000 cGy. Hepatic metastases were controlled for over 1 year with 3,240 cGy. The radiotherapy of pheochromocytoma and chemodectoma is reviewed, and the similarities between the two kinds of tumor are discussed. We speculate that a higher initial radiation dose might have resulted in a more sustained remission in our patient and recommend doses of 4,000-5,000 cGy if they can be safely administered, in 4-5 weeks for pheochromocytomas.

Adrenal Gland Neoplasms↗
PubMed1993

Nonlinear heart model predicts range of heart rates for 2:1 swinging in pericardial effusion.

We analyze two mathematical models of Rigney and Goldberger (14) of heart swinging in large pericardial effusions. Both models represent the torques due to the outflow of blood from the heart. The first assumes that the duration of systole does not vary with heart rate (in beats/min), whereas the second assumes that it varies linearly with heart rate. We examine the motion of the heart for heart rates between 50 and 200 and for a range of initial positions and velocities. Both models predict that the heart swings once every other beat (2:1 swinging, giving rise to electrical alternans) in a discrete range of heart rates and swings once per beat otherwise; both models explain the appearance and disappearance of 2:1 swinging mathematically. The first model predicts a rate range from 105 to 116 for the occurrence of 2:1 swinging. The second model predicts the same qualitative behavior but with 2:1 swinging occurring at heart rates between 88 and 119, which agrees well with published clinical data showing 2:1 swinging at heart rates between 90 and 144. We describe an analysis program for ordinary differential equations that analyzed the models quickly and automatically.

Animals↗
PubMed1988

Epibulbar fibroma of the conjunctival substantia propria.

A 39-year-old black woman had a 12-year history of slowly progressive left temporal juxtalimbal conjunctival swelling. The lesion was freely movable over the surface of the globe and was believed to be situated within the substantia propria. Histopathologic evaluation of the excised tissue disclosed that it was a collagenous mass of lamellar architecture, with a hypocellular dispersion of mesenchymal cells and a scattering of capillaries in the absence of inflammation. Electron microscopic examination revealed that the lamellar arrangement had regular lobular subdivisions composed of collagen fibers approximately 50 nm in diameter. Compressed fibroblasts occupied the peripheries of the lobules; the former exhibited abundant rough-surfaced endoplasmic reticulum and failed to elaborate basement membrane material. Delicate processes of the fibroblasts extended into the centers of the collagenous aggregates. To our knowledge, this is the first convincingly documented case of an acquired fibroma of the substantia propria of the epibulbar conjunctiva. The differential diagnosis in this case included related fibroblastic and simulating nonfibroblastic lesions.

Adult↗
PubMed1987

Multifocal static creamy choroidal infiltrates. An early sign of lymphoid neoplasia.

Three patients, each more than 60 years of age at initial presentation, had early stage lymphoid infiltrates (formerly called reactive lymphoid hyperplasia) of the choroid and contiguous extraocular tissues. There were multifocal, confluent, and nonconfluent creamy patches in the choroid. These lesions changed very little over periods of observation ranging from 1 to 4 years and failed to produce ophthalmoscopically visible disturbances of the retinal pigment epithelium (RPE). Fluorescein angiography demonstrated dye collection within the lesions without leakage into the subretinal or subpigment epithelial spaces. Both ultrasonography and computed tomography (CT) showed thickening of the choroid with either anterior or posterior episcleral extensions of lymphoid tissue. Pathologic evaluation of biopsy specimens of extraocular portions of the lesions showed low-grade tumors that were diffuse infiltrates of mature lymphocytes, which exhibited lymphoplasmacytoid features, Dutcher bodies, or small residual germinal centers (so-called borderline lesions). Two patients had uniocular localized disease, whereas the third had bilateral ocular lesions, hypogammaglobulinemia, and another extranodal chest wall lymphoid tumor. Therapy for the localized ocular condition consisted either of oral administration of corticosteroids or low doses of radiotherapy.

Aged↗
PubMed1987

Canaliculops.

Over a 1-year period, a cystic bluish coloration developed in the most medial aspect at the margin of the right upper eyelid of a 40-year-old man. The clinical diagnoses were either a conjunctival inclusion cyst or an adnexal cyst, possibly of the gland of Moll. The excised specimen was studied histopathologically and exhibited a lining that was virtually indistinguishable from that of the normal canaliculus, except for hyperplasia of the cellular wall and the focal presence of a superficial mucin-producing columnar cell monolayer at the lumen. The medial edge of the excised specimen showed a merging of the cyst into a nonectatic portion of the canaliculus. Inflammation in the wall of the cyst and in this terminal portion of the canaliculus was not identified. This is believed to be a unique entity of an idiopathic ectasia with mild epithelial proliferation of a segment of the canaliculus. The authors have termed this condition canaliculops, to draw a parallel between it and ectasia of the ducts of the lacrimal gland, so-called dacryops.

Adult↗
PubMed1987

Multiple bilateral apocrine cystadenomas of the lower eyelids. Light and electron microscopic studies.

An 88-year-old man presented with 13 apocrine cystadenomas of both lower eyelids of at least 10 years' duration. The cysts were remarkable for possessing a superior dome of either creamy or yellowish material (probably reflecting the lipid-rich decapitation secretion), surmounting a clearer fluid inferiorly, as well as for being restricted to the eyelid margins where the glands of Moll are located. Light microscopy disclosed a double-layered cuboidal cellular lining, which focally became more plump or hobnailed, exhibited apical decapitation secretion, and was occasionally thrown into papillary folds. Electron microscopy demonstrated cellular debris and segments of interrupted plasmalemmas within the cystic cavity, intercellular widenings constituting canaliculi, cytoplasmic election-dense secretory granules, flocculent mucous vacuoles, and swirls of smooth-surfaced endoplasmic reticulum. Basal cells were focally interspersed between the secretory cells and the basement membrane, and occasionally manifested spotty myofilamentary differentiation. These findings are supportive of an origin of the lesions from the secretory rather than the ductal portion of the glands of Moll. They corroborate conclusions drawn from dermatologic investigations that the cysts are an essentially proliferative process as opposed to the result of passive ductal dilatation.

Aged↗
PubMed1986

The effects of nuclear magnetic resonance imaging on ocular tissues.

Nuclear magnetic resonance, an imaging technique with great promise for detecting cerebral abnormalities, was studied to determine its possible deleterious effects on the mammalian eye. Young (3.5-week-old) Columbia-Sherman rats were exposed simultaneously to a constant magnetic field of 2.7 tesla and radio frequency pulses of 29 MHz at 800-ms intervals for six hours at field strengths representing the maximum used in a clinical setting. The six-hour exposure is many times greater than the four to six minutes currently employed in most diagnostic protocols. The animals were examined by slit-lamp biomicroscopy and ophthalmoscopy at regular intervals. Autoradiograms of lenses from animals injected with tritiated thymidine prior to exposure did not reveal any disturbances in cell-cycle kinetics. Eyes from rats not previously injected with the isotope were processed for cytopathologic analysis at various intervals. A two-year follow-up has indicated that at both the slit-lamp biomicroscopic and the light microscopic levels, there were no discernable effects on the rat eye.

Animals↗
PubMed1986

A comparison of conjunctival and nonocular dendritic cells utilizing new monoclonal antibodies.

Langerhans cells belong to the dendritic cell family. Their presence in the conjunctiva and cornea has been demonstrated by means of various membrane and cytoplasmic markers. Utilizing OKT6, a monoclonal antibody that specifically binds to Langerhans cells in conjunction with la histocompatibility antigens (HLA-DR), and a new panel of monoclonal antibodies, we compared the population density and characteristic phenotypes of Langerhans cells in normal conjunctiva with those in normal epidermis. A greater density of Langerhans cells was noted in epidermis in comparison with conjunctiva. Various areas of the conjunctiva and cornea were mapped for Langerhans cell distribution. The T6/la ratio of Langerhans cells in conjunctiva was notably different from that in skin. Utilizing the Prolm2 marker, we identified non-Langerhans dendritic cells in the substantia propria and in the basilar epithelium of the conjunctiva, antigen-processing cells probably identical to the interdigitating dendritic cells of lymph nodes.

Antibodies, Monoclonal↗
PubMed1985

Epilepsy in a community--management and social impact.

A clinic for adult epileptics run by a primary health care centre was "medically' audited to assess the quality of care, aetiological factors and social implications of this condition in the community served. It was found that drug compliance is poor (55%), and seizure control is suboptimal. There is a high incidence (38%) of post-traumatic epilepsy. The patients predominantly rely on social welfare for support--only 11% are self-supporting and 62% receive a disability grant. The role of a special clinic for co-ordinated and comprehensive continuing care is emphasized.

Adolescent↗
PubMedDate not supplied

Endonasal laser-assisted dacryocystorhinostomy.

Dacryocystorhinostomy is a procedure that is performed to allow drainage of tears from the lacrimal sac directly into the nasal cavity. Endonasal telescopes facilitate performance of this operation with better visualization and decreased morbidity. We present our experience with endoscopic laser-assisted DCR. In the last 31 months, we have performed 31 procedures on 23 patients with either the holmium:YAG laser or the argon:HGM laser. We have a 97% overall success rate with a mean follow-up of 16 months. Our series includes both adult and pediatric patients as well as five revision procedures after failed external DCR. We present our technique, results, and the reasons for our change in laser delivery systems. Most importantly, we discuss the technical factors that contribute to our overall success. These include a large rhinostomy size, simultaneous correction of intranasal and/or sinus pathology, the avoidance of laser use within the lacrimal sac, and close postoperative monitoring with intranasal debridement. We conclude that endoscopic laser-assisted DCR is a better alternative to standard external DCR because it avoids a cutaneous scar, excessive tissue injury, and postoperative morbidity.

Adult↗