PubMed Health⌕ Search

Biomedical subjects

G A Cioffi

Publications and source records attributed to G A Cioffi.

54 records · Page 3Linked to original sources
PubMed1995

An in vivo model of chronic optic nerve ischemia: the dose-dependent effects of endothelin-1 on the optic nerve microvasculature.

The purpose of this study was to evaluate the effects induced by chronic microapplication of endothelin-1 on the anterior optic nerve microvasculature and to determine the dose-response characteristics of endothelin-1 on this vascular bed. Daily dosages between 4.69 x 10(-4) and 9.0 x 10(-1) micrograms/day of endothelin-1 were delivered continually over 3 days, and at a constant flow rate, to the perineural region of the anterior optic nerve of 15 albino rabbits via osmotically-driven minipumps. The vasomotor effect of local endothelin-1 on the microvasculature of the optic nerve was examined using intraluminal microvascular corrosion casting technique. The vasomotor effects were quantified by measuring the relative amount of vasoconstriction of the arterioles supplying the anterior optic nerve (primary and secondary branches of the short posterior ciliary arteries). The average constriction was calculated for the endothelin-treated eyes and the untreated, contralateral eyes. The mean vasoconstriction in the endothelin treated eyes ranged from 14.7% to 30.0% and was highly correlated with the logarithmic value of the daily dose of endothelin-1 (R2 = 0.59, p = 0.00083). The interocular difference (between treated and untreated eyes) of the optic nerve vasoconstriction ranged from 0-19% (mean +/- SD: 7.23 +/- 5.7%). This interocular difference also correlated highly with the log of the daily endothelin-1 dosage (R2 = 0.80; p < 0.0001). By additionally accounting for the weight and sex in a multiple linear regression function, the correlation was markedly improved (R2 = 0.92; p < 0.0001). In conclusion, the microvasculature supplying the anterior optic nerve of the rabbit demonstrates a dose-dependent vasoconstriction with chronic local application of endothelin-1. This in vivo, experimental model offers a titratable method with which the effects of chronic vasoconstriction and vascular insufficiency on the optic nerve can be examined.

Animals↗
PubMed1995

Reproducibility of topometric data with a scanning laser ophthalmoscope in rabbits.

The Heidelberg Retina Tomograph is a confocal scanning laser ophthalmoscope which obtains three-dimensional images of the optic nerve head and the retina in the human eye. Because of its potential investigative uses in experimental animal models of glaucoma, we examined its variability with optic nerve head measurements in the rabbit eye. Three topographic images, recorded on different days, were acquired from the right eye of 5 New Zealand white rabbits over 3 weeks. To estimate the lowest possible variability, a second series of three images was recorded in a single setting without displacement of the rabbits. The average coefficient of variability (standard deviation/mean) for the estimate of the optic nerve head cup volume (volume below surface) was 11.1% in the independent series and was decreased to 3.0% in the sequentially recorded series without displacement of the rabbits (P < 0.001). These values indicate a comparable variability for the estimate of the optic nerve head cup volume in the rabbit compared with those reported for the human eye. This variability is considerably decreased by maximally standardizing the image acquisition position, suggesting that variability largely depends on the alignment between the subject and the laser-scanner.

Animals↗
PubMed1994

Microvasculature of the anterior optic nerve.

The traditional definition of glaucoma as a disorder of increased intraocular pressure (IOP) oversimplifies the clinical situation. Some glaucoma patients never have higher than normal IOP and others continue to develop optic nerve damage despite maximal lowering of IOP. Another possible factor in the etiology of glaucoma may be regulation of the regional microvasculature of the anterior optic nerve. One reason to believe that microvascular factors are important is that many microvascular diseases are associated with glaucomatous optic neuropathy. In this study, endothelin-1 was used to produce vasoconstriction of the ocular vasculature following both intravitreal and perineural delivery. Intravitreal injections (1.25 and 2.50 micrograms) were given to six rabbits to assess the vascular response of the posterior segment. In addition, endothelin (0.0-4.2 micrograms) was delivered with an osmotically driven minipump system to the perineural region of six rabbits. Vasoconstriction of the anterior optic nerve vasculature was observed following both methods of endothelin delivery. A better understanding of the microvasculature of the anterior optic nerve is needed to evaluate its relationship to glaucomatous damage. Modulation of this vascular supply, with agents that mimic autoregulatory controls, may allow the sites of vasomotor control to be established and, in the future, their status to be manipulated.

Animals↗
PubMed1993

Corneal trabeculectomy without conjunctival incision. Extended follow-up and histologic findings.

BACKGROUND: Corneal trabeculectomy, a guarded filtration procedure without conjunctival incision but with an iridectomy, was developed in 30 eyebank and 20 rabbit eyes before being applied to humans. METHODS: Corneal trabeculectomy was performed in one eye and conventional trabeculectomy in the contralateral eyes of six rabbits. Sequential postoperative histologic examinations were performed on these eyes at various times after surgery. Corneal trabeculectomy also was performed in 20 eyes of 18 patients with glaucoma for control of their intraocular pressure (IOP). RESULTS: Results of histologic examination on these rabbit eyes showed less subconjunctival inflammation and fibrosis after corneal trabeculectomy than conventional trabeculectomy. In the eight patients with glaucoma who had had their surgery at least 1 year previously, the mean IOP decreased from 31 mmHg (preoperatively) to 14 mmHg. Eighty-eight percent have IOPs less than or equal to 18 mmHg without medications or revision. CONCLUSION: Extended follow-up shows that corneal trabeculectomy is a low-tech, relatively atraumatic filtration procedure without conjunctival incision, which produces diffuse and persistent blebs and controls IOP. Results of sequential postoperative histologic examination in rabbit eyes suggest that corneal trabeculectomy may incite less subconjunctival inflammation than conventional trabeculectomy.

Adult↗
PubMed1993

Confocal laser scanning ophthalmoscope. Reproducibility of optic nerve head topographic measurements with the confocal laser scanning ophthalmoscope.

BACKGROUND: Glaucoma is an optic neuropathy in which changes in the appearance of both the optic nerve head and the surrounding tissues are important in both diagnosing its presence and progression. Accurate methods to objectively document the appearance of the optic nerve are necessary. The confocal laser scanning ophthalmoscope (Zeiss) is a new prototype instrument that may have the capability to accurately perform this function. METHODS: The authors performed a prospective pilot study evaluating the ability of the confocal laser scanning ophthalmoscope to reproduce three-dimensional optic nerve images. Each retinal image contained 600,000 bytes of information. Thirty discrete images of the right optic nerves of 19 visually normal volunteers were obtained. Depth measurements were compared from the same 100 x 100 micron areas (neighborhoods). RESULTS: Image comparisons found the variability of depth measurements for the entire image were within 102 microns (95% confidence interval). Sixty percent of the depth measurements were reproducible within 100 microns. Variability of the depth measurements was greatest where the neuroretinal rim sloped at the edge of the optic cup and lowest in the peripapillary area. CONCLUSION: The confocal laser scanning ophthalmoscope has the potential to be a safe, rapid, and reproducible method of imaging ocular structures.

Adult↗
PubMed1992

Recent developments in the surgical treatment of glaucoma.

Surgical treatment of the glaucomas continues to evolve with the advent of new techniques and adjunct therapies. The modulation of wound healing with antimetabolites has increased the success and predictability of filtration surgery. Silicone tube shunts continue to be developed and improved for use in refractory glaucoma. Preoperative factors, such as long-term topical medications, may contribute to the success or failure of filtration surgery. Early recognition of postoperative complications and effective management of these complications may also enhance the success of filtration surgery. The debate over combined surgical procedures for glaucoma and cataract persists. This article reviews recent developments in the surgical treatment of glaucoma.

Antimetabolites↗
PubMed1991

Modified optic nerve decompression in patients with functioning lumboperitoneal shunts and progressive visual loss.

Chronic papilledema from pseudotumor cerebri can cause progressive visual loss despite functioning lumboperitoneal shunts. The authors performed modified optic nerve sheath decompression in 12 patients (16 operations) with functioning lumboperitoneal shunts and progressive visual loss. All of the patients demonstrated improvement in visual function. Optic nerve sheath decompression allows release of localized cerebrospinal fluid (CSF) pressure. By performing optic nerve sheath decompression, progressive visual loss secondary to chronic papilledema can be halted and reversed.

Adult↗
PubMed1989

Virus-associated dysplasia (bowenoid papulosis?) of the oral cavity.

We are presenting a case of multifocal, virus-associated dysplasia of the oral cavity. We believe this case represents bowenoid papulosis, which usually is limited to the genital region. The patient, a 21-year-old white man, had recently completed therapy for Hodgkin's disease. An oral examination revealed multiple red 3 to 6 mm macules scattered over the oral mucosa, involving the buccal and labial mucosa, palate, and gingiva. The favored clinical diagnosis was candidiasis. Histologically, the biopsy specimen showed severe epithelial dysplasia. Three additional oral biopsies of different sites were performed and revealed similar histology. Immunohistochemical stains for human papillomavirus were done, and two of four lesions stained positively. Transmission electron microscopy revealed intranuclear viral particles consistent with human papillomavirus. Further questioning and examination of the patient revealed that he had lesions of the penis that were clinically and histologically bowenoid papulosis. In addition, he admitted to oral-genital sex during the period of therapy for Hodgkin's disease. This is the first reported case of oral bowenoid papulosis, and it supports a viral cause for this disease process.

Adult↗
PubMed1988

Total joint replacement: a consideration for antimicrobial prophylaxis.

Infection is the principal and most devastating complication of total joint replacement, resulting in long periods of hospitalization, staggering costs, loss of the implant, disastrous physical impairment, and even death. Staphylococcus aureus and Staphylococcus epidermidis account for more than 50% of late infections. Animal studies have shown that joint implants are at a high risk of becoming infected via a metastatic hematogenous route during transient bacteremias. Because cephalosporins have been established as the perioperative and intraoperative agents of choice to prevent infections related to total joint replacement, oral cephalosporins are the drugs of choice to minimize the potential for the metastatic infection of prosthetic joints associated with transient dental bacteremias. Clindamycin is preferred for patients who are allergic to the cephalosporins or who may have a cross-allergy between penicillin and the cephalosporins.

Anti-Bacterial Agents↗
PubMed1986

Cutaneous draining sinus tract: an odontogenic etiology.

Although the most common cause of the intermittently suppurating cutaneous sinus tract in the face and neck area is chronic dental infection, chronic draining sinus tracts of the face and neck continue to be a diagnostic challenge. The attending clinician must look carefully for a potential odontogenic infection; chronicity, lasting for weeks, months, and even years and the recognition of the lesion as a sinus tract are keys to making the correct diagnosis. Diagnostic errors can result in multiple surgical excisions and biopsies, long-term antibiotic therapy, and even radiation therapy or electrodesiccation. A review of 137 cases of cutaneous draining sinus tracts from the literature is presented, and four cases are reported. Conservative, nonsurgical root canal therapy is recommended as the first choice of treatment.

Adolescent↗
PubMed1986

Oral surgery. Diagnostic, prognostic, and treatment planning considerations.

The surgical management of a patient begins at the moment of presentation for treatment and does not end until the problem is resolved and health restored. Alternatively, referral may be good management in some cases. Any procedure accomplished along the way is but one event in the course of overall surgical management. A regard for the basic requirements and principles of good surgery integrated with a careful consideration of the treatment planning and prognostic indicators for the removal of teeth completes a sequential evaluation of the total patient, his pathosis and his ability to tolerate and respond to the treatment. Guiding principles, careful procedures and continued postoperative concern form a triad of good practice.

Dental Care for Persons with Disabilities↗
PubMed1985

The hemodynamic and plasma catecholamine responses to routine restorative dental care.

Eleven healthy, normotensive males undergoing routine restorative dental care were evaluated during treatment for possible hemodynamic alterations in response to potential sympathetic nervous system stimulation. It is concluded that once acceptable local anesthesia is achieved, the hemodynamic and sympathetic responses to routine restorative dental care are minimal. These findings serve as a baseline for further studies evaluating the response of medically and pharmacologically compromised patients to similar dental procedures.

Adult↗
PubMedDate not supplied

Assessment of human ocular hemodynamics.

Vascular abnormality and altered hemodynamics play important roles in many ophthalmic pathologies. Much of our knowledge of ocular hemodynamics was gained from invasive animal research, although a number of noninvasive methods suitable for in vivo use in humans have been developed. Data from these methods now produce a significant literature of their own. Understanding the origins of the data and appreciating their limitations can be difficult. Modern hemodynamic assessment techniques each examine a unique facet of the ocular circulation. No single facet provides a complete description of the hemodynamic state of the eye. These methods have contributed a great deal to our understanding of normal hemodynamics. More importantly, they continue to add to our understanding of altered hemodynamics found in disease. Some have found their way into limited clinical practice. The predominant ocular hemodynamic assessment techniques are reviewed with the aims of introducing the fundamental principles behind each, highlighting their inherent advantages and limitations, highlighting their contributions to understanding ocular physiology, and considering their potential to provide signs for diagnosis.

Animals↗
PubMedDate not supplied

The effect of chronic ischemia on the primate optic nerve.

PURPOSE: To develop an in vivo model of chronic optic nerve ischemia to study the role of vascular insufficiency in the development of glaucomatous optic neuropathy. METHODS: We surgically implanted osmotically-driven mini-pumps that allowed the continuous micro-application of 0.2 micrograms/day of endothelin-1 (ET-1) into the retrobulbar optic nerve of rabbits and rhesus monkeys. ET-1 was delivered for 2 to 6 months, following which histological studies were performed. RESULTS: Both rabbits and primates experienced a 35% to 38% decrease in optic nerve blood flow with corresponding focal narrowing of the vessels supplying the optic nerve. In the rabbit model, optic disc excavation and histologic tissue loss in the anterior optic nerve resulted from the induced ischemia. CONCLUSIONS: Chronic ischemia of the primate anterior optic nerve induced with endothelin-1 infusion resulted in diffuse loss of axons without a change in the intraocular pressure.

Animals↗