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Biomedical subjects

P S Levin

Publications and source records attributed to P S Levin.

At least 19 recordsLinked to original sources
PubMed2001

Long-term results of irradiation for patients with progressive Graves' ophthalmopathy.

PURPOSE: To determine the long-term outcome of radiotherapy (RT) in patients with progressively symptomatic thyroid eye disease and to evaluate the potential long-term sequelae. METHODS AND MATERIALS: Four hundred fifty-three patients provided written informed consent and received retrobulbar RT for Graves' ophthalmopathy at Stanford University Medical Center; 197 with 1 year of follow-up were retrospectively analyzed. Of the 197 patients, 189 received RT to the bilateral retrobulbar regions, and 4 received unilateral RT. The technical information was unavailable for 4 patients. Patients were assessed by chart review, telephone interview, questionnaire, and multidisciplinary physician examination. Eye impairment was scored using the SPECS system. The end point review included the before and after treatment SPECS score, surgical intervention, and patient satisfaction. Potential complications, including cataract development, retinopathy, and tumor formation, were investigated. Multivariate analyses were performed to assess the prognostic variables. RESULTS: Improvement or resolution was 89% for soft-tissue findings; 70% for proptosis; 85% for extraocular muscle dysfunction; 96% for corneal abnormalities; and 67% for sight loss. The response to RT may take >6 months to stabilize. Factors predictive of response varied in the individual SPECS categories but included the initial SPECS score, pretreatment thyroid status, female gender, a 20-Gy RT dose, and a history of hypertension. Nonpredictive factors included a history of tobacco use, diabetes mellitus, steroids, and prior cataracts. Only 16% required surgical intervention to preserve their vision or restore binocular vision. Twenty-two patients (12%) developed cataracts after irradiation (median 11 years). No patient developed a tumor within the RT field during the follow-up period (range 1-29 years). Ninety-eight percent of patients were pleased with their results, and 2% believed their symptoms progressed despite RT. CONCLUSIONS: Retrobulbar irradiation (20 Gy) is safe and effective treatment for progressive Graves' ophthalmopathy, with a 96% overall response rate, 98% patient satisfaction rate, and no irreparable long-term sequelae, with follow-up extending 29 years. The most common late effect observed was cataract development, which occurred more frequently in older patients and was reversible with extraction. Elective surgical intervention after RT should be withheld until patients have demonstrated a plateau in response.

Adolescent↗
PubMed2001

The road to extinction is paved with good intentions: negative association of fish hatcheries with threatened salmon.

Hatchery programmes for supplementing depleted populations of fish are undergoing a worldwide expansion and have provoked concern about their ramifications for populations of wild fish. In particular, Pacific salmon are artificially propagated in enormous numbers in order to compensate for numerous human insults to their populations, yet the ecological impacts of this massive hatchery effort are poorly understood. Here we test the hypothesis that massive numbers of hatchery-raised chinook salmon reduce the marine survival of wild Snake River spring chinook, a threatened species in the USA. Based on a unique 25-year time-series, we demonstrated a strong, negative relationship between the survival of chinook salmon and the number of hatchery fish released, particularly during years of poor ocean conditions. Our results suggest that hatchery programmes that produce increasingly higher numbers of fish may hinder the recovery of depleted wild populations.

Animals↗
PubMed1998

Differential response of glomerular epithelial and mesangial cells after subtotal nephrectomy.

Recent studies in both human and experimental chronic renal disease suggest that there is a linkage between glomerular hypertrophy and glomerulosclerosis. To further define these relationships, we studied the changes in glomerular hypertrophy, procollagen alpha 1(IV) mRNA levels and glomerulosclerosis in rats undergoing 1 2/3 nephrectomy (Nx) or sham nephrectomy (SNx). Glomerular hypertrophy, measured biochemically by RNA/DNA and protein/DNA ratios, was significantly increased in Nx compared to SNx two days after subtotal renal ablation (RNA/DNA: Nx = 133 +/- 8%, SNx = 100 +/- 3% of the mean control value, P < 0.01; protein/DNA: Nx = 164 +/- 22%, SNx = 100 +/- 10%, P < 0.05) and remained elevated after 7 and 15 days (RNA/DNA: seven days Nx = 155 +/- 3%, SNx = 100 +/- 13%, P < 0.01; 15 days Nx = 303 +/- 21%, SNx = 100 +/- 24%, P < 0.001; protein/DNA: seven days Nx = 228 +/- 57%, SNx = 100 +/- 18%, P < 0.05; 15 days Nx = 341 +/- 23%, SNx = 100 +/- 18%, P < 0.01). Light microscopic measures of glomerular tuft volume (GTV) were too insensitive to detect glomerular enlargement until 15 days postoperatively, but GTV measured ultrastructurally demonstrated a 20% increment in Nx compared to SNx as early as two days postoperatively (P < 0.01). The latter increment in GTV was due exclusively to glomerular visceral epithelial cell (GVEC) expansion. Glomerular procollagen alpha 1(IV) mRNA levels were significantly elevated only 15 days after nephrectomy (Nx = 265 +/- 58% of the mean control value, SNx = 100 +/- 12%, P < 0.05; corrected for beta-actin mRNA levels). As this time, exuberant mesangial expansion measured ultrastructurally contributed to a 1.6 +/- 0.1-fold increase in GTV (P < 10(-5)), and to a relative decrement in the GVEC contribution to glomerular cells plus matrix (P < 0.01). Segmental sclerosis was observed only 15 days postoperatively in Nx (Nx = 1.3 +/- 0.4% of glomeruli evaluated, SNx = 0.0%, P < 0.05), and there was a strong correlation between the prevalence of segmental sclerosis and the procollagen alpha 1(IV) mRNA levels in Nx at 15 days (r = 0.93, P < 0.01). There was no significant correlation between the RNA/DNA and protein/DNA ratios and procollagen alpha 1(IV) mRNA levels. Thus, glomerular regions responded differentially to subtotal nephrectomy. Early epithelial cell expansion was followed by later mesangial expansion. Glomerular procollagen alpha 1(IV) mRNA levels were elevated only during the second (mesangial) phase of glomerular hypertrophy, when it correlated with glomerulosclerosis, but not during the initial (epithelial) phase, a pattern consistent with a mesangial origin of the procollagen alpha 1(IV) mRNA.

Animals↗
PubMed1998

Balanced orbital decompression for Graves' ophthalmopathy.

OBJECTIVE/HYPOTHESIS: Surgical management of Graves' ophthalmopathy is an alternative to medical therapy with corticosteroids or external beam radiotherapy. Orbital decompression has commonly been performed via a transantral approach to the medial orbital wall and floor. Although an endoscopic approach to these walls has been described, a balanced approach (incorporating a lateral decompression by an ophthalmology team) is desirable. STUDY DESIGN: Retrospective review. METHODS: Endoscopic medial decompression and extended lateral decompression were accomplished in 18 orbits (11 patients); inferior decompression was performed in 11 of these. Five additional procedures were performed. RESULTS: Exophthalmos improved by a mean of 4.6 mm. All patients who underwent decompression for vision loss had improved vision after surgery. Exposure keratitis improved in six of six orbits. Two of five patients undergoing orbital decompression for vision loss developed postoperative diplopia, which was successfully treated with strabismus surgery or prism glasses. There were no other significant complications. CONCLUSIONS: The endoscopic approach to the medial orbital wall is an important component of balanced orbital decompression for patients with Graves' ophthalmopathy. Balancing the decompression and preserving the medial orbital strut between the ethmoid cavity and the orbital floor may minimize the risk of diplopia.

Adult↗
PubMed1992

Endocanalicular laser-assisted dacryocystorhinostomy. An anatomic study.

In human cadaver specimens, a laser fiberoptic was advanced through the canalicular systems to create fistulas between the nasolacrimal sac and nose. A 400- to 600-microns, blunt-tipped quartz fiberoptic was then advanced through the upper and/or lower canaliculus to the medial aspect of the nasolacrimal sac. After 10 to 15 laser pulses (10 W for 0.1 second), a 2.5 x 2.5-mm fistula was created between the lacrimal sac and the nose just anterior and inferior to the middle turbinate. Additional laser pulses can further enlarge the fistula. Endocanalicular laser-assisted dacryocystorhinostomy has potential advantages compared with endonasal laser-assisted dacryocystorhinostomy, including the following: laser energy is directed away from the eye; the technique resembles standard nasolacrimal probing; and nasal endoscopy and instrumentation may prove unnecessary.

Dacryocystorhinostomy↗
PubMed1992

Early increased renal procollagen alpha 1(IV) mRNA levels in streptozotocin induced diabetes.

Changes in renal procollagen mRNA levels were measured shortly after the induction of streptozotocin induced diabetes in the rat. "Medullary" procollagen alpha 1(IV) levels seven days after diabetes induction was significantly higher in untreated diabetic rats (DM, N = 12; 244 +/- 57% of the mean control value), than in diabetic rats receiving small doses of insulin insufficient to achieve euglycemia (NPH, N = 10; 87 +/- 12%) and in diluent injected nondiabetic control rats (C, N = 15; 100 +/- 12%; P less than 0.01, DM vs. C and DM vs. NPH). "Medullary" procollagen alpha 1(I) mRNA levels were numerically increased in DM to a lesser degree (141 +/- 5%, ANOVA not significant) compared to C (100 +/- 13%), and this small increment was further normalized by insulin treatment (NPH, 120 +/- 11%). A trend for increased beta-actin mRNA levels in DM did not reach significance (P greater than 0.05). Increases in "medullary" procollagen mRNA levels did not correlate with kidney weight, glomerular tuft volume, creatinine clearance, food intake, or body weight gain, and occurred when renal morphology was normal by light microscopy. Statistically significant but weak correlations were noted between the serum glucose levels and "medullary" procollagen alpha 1(IV) mRNA levels (r = 0.43, P less than 0.05). In addition, weak correlations were noted between glycosuria and "medullary" procollagen alpha 1(I) levels (r = 0.38, P less than 0.05). In situ hybridization studies localized the increased procollagen alpha 1(IV) mRNA levels predominantly in the DM group primarily in the deep cortex and medullary outer stripe of proximal tubules. Glomerular procollagen alpha 1(IV), alpha 1(I), alpha 1(III) and beta-actin mRNA levels were not increased in untreated diabetic rats 7 or 28 days after diabetes induction. Thus, tubular procollagen alpha 1(IV) mRNA levels increased prior to any measurable change in glomerular levels and were ameliorated by insulin administration.

Animals↗
PubMed1991

A 20-year series of orbital exenteration.

We reviewed patient records of 99 consecutive orbital exenterations performed between 1969 and 1988. Patients ranged in age from 2 to 86 years (mean, 55.9 years). Classification of cases on histopathologic criteria showed 32 exenterations were performed for squamous cell carcinoma originating in the paranasal sinus (13), skin (12), conjunctiva (six), and lacrimal sac (one). Orbital exenteration was performed for treatment of other epithelial malignancy in basal cell carcinoma (eight), sebaceous carcinoma (six), adenoid cystic carcinoma (five), undifferentiated carcinoma (four), adenocarcinoma (two), intraepithelial carcinoma of the conjunctiva (two), benign mixed tumor (one), and transitional cell carcinoma (one). Exenterations were performed for melanoma of the conjunctiva (ten), nasosinus (three), skin (two), orbit (two), and choroid (one). Exenterations were also performed as treatment for mucormycosis (five), meningioma (three), fibrosarcoma (two), rhabdomyosarcoma (two), hemangiopericytoma (two), orbital cellulitis (one), fibrous histiocytoma (one), schwannoma (one), lymphangioma (one), benign lymphoepithelial lesion (one), and undifferentiated malignancy (one).

Adolescent↗
PubMed1991

Orbital exenteration. The reconstructive ladder.

Following orbital exenteration, there is a spectrum of immediate and delayed options for orbital reconstruction. Goals of reconstruction after exenteration include detection of recurrent disease, restoration of boundaries between the orbit and surrounding structures, and optimal aesthetics. Local solutions to problems of the exenterated orbit, such as healing by granulation or application of split-thickness skin grafts, are advantageous for detecting recurrent disease. Regional solutions, involving transfer of periorbital tissue into the orbit, may mask recurrent disease and create adjacent deformity; however, these solutions can be used to restore orbital boundaries and shallow the orbital cavity. Distant solutions, such as skin-muscle flaps and free tissue grafts, allow for facial reconstruction in patients with extensive orbital and periorbital defects.

Adipose Tissue↗
PubMed1990

Polytef (polytetrafluoroethylene) alloplastic grafting as a substitute for mucous membrane.

Nine patients with contracted sockets, cicatricial conjunctival shortening, or severe symblepharon formation were treated by temporary grafting with polytef (polytetrafluoroethylene) alloplastic surgical membrane in place of autogenous mucous membrane. Within 2 weeks of the grafting, the patients' residual conjunctival epithelium grew beneath the alloplastic membrane and covered the raw surfaces of the reconstructed socket. The procedure produced satisfactory results in eight of nine patients without the need for harvesting mucous membrane from the mouth or nose. Healing was rapid and without the discomfort and potential complications associated with grafting of autogenous mucosa.

Aged↗
PubMed1988

Orbital surgery. The technique of coronal scalp flap approach to the qateral orbitotomy.

Lateral orbitotomy may be performed using a coronal scalp flap to provide exposure of the lateral orbital wall and rim. A coronal incision is made across the scalp. The scalp flap is developed anteriorly to expose the orbital margin from the superior orbital rim to the zygomatic arch. The temporalis muscle is dissected from its bony attachments and bluntly retracted, providing maximal exposure of the lateral orbital wall. The orbitotomy proceeds as required. The case concludes with a layered closure. In selected patients, the coronal scalp flap provides improved exposure and postoperative aesthetics compared with approaches in which the skin and muscle layer are incised directly over the lateral orbit. Complications are infrequent.

Humans↗
PubMed1987

The technique of cranial bone grafts in the correction of posttraumatic orbital deformities.

The technique of split-thickness cranial bone graft for reconstructive orbital surgery, is reported in five patients who sustained extensive orbital trauma. This technique involves exposing the skull via a coronal scalp incision, after which the cranial bone is split in situ along the diploe. The outer table of the cranial bone is then used as a graft to correct orbital defects and other associated bony deformities. Cranial bone grafts have several advantages over other graft sites in orbital reconstruction, including more rapid postoperative recovery, close proximity of donor site to recipient site, and improved survival of cranial bone grafts in experimental studies. Cranial bone grafts are an important source of autogenous tissue for the reconstructive surgeon.

Adolescent↗
PubMed1987

Successful treatment of Paecilomyces lilacinus endophthalmitis following cataract extraction with intraocular lens implantation.

We report a case of mycotic endophthalmitis caused by Paecilomyces lilacinus after cataract surgery. Treatment consisted of early vitrectomy, multiple intravitreal injections of amphotericin B and miconazole, intravenous miconazole and, later, oral ketoconazole. The intraocular lens, which initially appeared uninvolved, was removed six weeks after initiation of therapy and found to contain causative organisms. Final visual acuity was 20/20. We recommend aggressive therapy consisting of early vitrectomy, intravitreal injections repeated as necessary, removal of the intraocular lens, avoidance of intraocular steroid, and administration of systemic antifungal agents.

Aged↗
PubMed1983

Histopathology of the eye in Cockayne's syndrome.

The eyes of a 44-month-old boy with Cockayne's syndrome had retinal pigmentary abnormalities that included variable pigmentation and excessive lipofuscin deposition in the retinal pigment epithelium and unusual pigmented cells in the retina and subretinal space. There was optic nerve atrophy with loss of nerve fibers and myelin sheaths and also atrophy of the retinal nerve fiber and ganglion cell layers consistent with the histologic features of a demyelinating disease. Widespread pigment dispersion was found in the anterior segment. There was no evidence of vascular disorder, ocular calcification, neuronal storage disorder, or dystrophic corneal changes.

Child, Preschool↗