Biomedical subjects
Publications and source records attributed to I Gutman.
An algorithm is described by means of which the Kekulé structures of a catacondensed benzenoid molecule (with h hexagons) are transformed into binary codes (of length h). By this, computer-aided manipulations with, and memory-storage of Kekulé structures are much facilitated. Any Kekulé structure can easily be recovered from its binary code.
An algorithm for the calculation of the hyper-Wiener index (WW) of benzenoid hydrocarbons (both cata- and pericondensed) is described, based on the consideration of pairs of elementary cuts of the corresponding benzenoid graph B. A pair of elementary cuts partitions the vertices of B into four classes. WW is expressed as a sum of terms of the form n11n22 + n12n21, each associated with a pair of elementary cuts; nrs, r, s = 1, 2 are the numbers of vertices in the respective four classes. The algorithm proposed enables a relatively easy calculation of WW, finding expressions for WW of homologous series of benzenoid hydrocarbons, and envisaging the relations between WW and molecular structure.
The classical Wiener index, W(G), is equal to the sum of the distances between all pairs of vertexes of a (molecular) graph, G. We now consider a related topological index, pi(G), equal to the product of distances between all pairs of vertexes of G. The basic properties of the pi index are established and its possible physicochemical applications examined. In the case of alkanes, pi and W are highly correlated; a slightly curvilinear correlation exists between In pi and W.
For a saturated hydrocarbon with n carbon atoms and m carbon-carbon bonds and with Randic connectivity index chi, two functions, L = L(n,m) and U = U(n,m), are determined, such that L < or = chi < U. These bounds are better than those previously reported; for most chemically relevant values of n and m there exist hydrocarbons for which chi = L or chi = U.
A 68-year-old woman presented with diplopia. Fluctuations of dysfunction of lateral rectus muscles in both eyes were detected on consecutive examinations. The diagnosis of ocular myasthenia was proposed. After the initiation of therapy, the patient complained of disturbing micropsia. The micropsia and diplopia were relieved by occlusion of one eye or by a base-out prism over one of the patient's eyeglass lenses. Mechanisms of micropsia are discussed.
Low-tension glaucoma (LTG) is manifested by glaucomatous optic nerve damage and visual field loss despite normal intraocular pressure (IOP). We describe 62 patients with classical signs of LTG. Computed tomography (CT) was performed in all patients. In 56 of the patients (90.3%), pathology of the intracavernous carotid arteries adjacent to the intracranial opening of the optic canal could be demonstrated. In 28 patients (45.2%) a clear asymmetry of the optic nerve cupping was found and could be correlated with the severity of the carotid artery pathology. A control group of 24 age-matched patients included five (20.8%) with intracavernous carotid artery calcification and only one (4.2%) with intracavernous ectasia. We suggest that calcification, dilatation and ectasia of the carotid artery into the optic canal may play an important role in the pathogenesis of many cases of LTG. The close proximity of the carotid artery to the optic nerve at this location may result in compressive neuropathy with subsequent glaucomatous damage of the optic nerve head.
This report describes the occurrence of acute transient myopia in a patient treated with sulfonamide. We followed this patient by performing A-scan ultrasonographic ocular measurements documenting the anterior chamber depth, lens thickness, and axial length during the acute and convalescent periods. The outstanding feature in this case was the documented ultrasonographically significant reduction of the anterior chamber depth combined with lens thickening. This could be caused by a forward displacement of the lens as a result of allergic ciliary body edema and rotation. These changes could explain the mechanism of drug-induced transient myopia.
A 68-year-old woman presented with acute visual loss, elevated intraocular pressure (IOP), and a flat anterior chamber combined with retinal and choroidal detachment. The diagnosis of orbital pseudotumor was based on the patient's poor response to conventional therapy and on computerized tomography and ultrasound findings. After treatment with oral corticosteroids, the inflammatory process, elevated IOP, and choroidal and retinal detachment resolved.
Lumbar spinal AP radiographs of 13 C3-T11 paraparetic patients taken at about a 10 year interval were compared. The height (H) and maximum width (W) of the interapophysolaminar spaces (IALS), the width of the vertebral bodies at their waist (V) and the relationship between them showed minimal change over the follow up period. The difference between the late and early mean IALS height values increased caudally but was statistically significant only below L5. Subjective evaluation of the consecutive x-ray films revealed few new degenerative abnormalities. It is concluded that the normal aging process, which includes horizontal spreading of the lumbar vertebral bodies and narrowing of the lumbar spinal canal, is not accelerated by paraparesis and may even be retarded by relative immobilization.
Malignant prolactinoma is a rare entity and only a few cases have been published. The diagnostic criteria and the clinical course remain unclear. We present a case of malignant prolactinoma in a woman with a 30-year duration of the disease. In the terminal stage of the disease the prolactinoma metastasized to the left eye, the prolactin level reaching 196000 mU/l. Bromocriptine in high doses was not effective. The response to pergolide was good in the first two years of treatment; thereafter an escape effect was observed. The patient died in a comatose state. A review of previously published cases follows.
Nd:YAG laser trabeculopuncture (YLT) was performed in 12 eyes of 12 patients with angle-recession glaucoma. Confluent, 1-clock-hour trabeculotomy was attempted in all eyes. The calculated average laser energy was 181 +/- 86 mJ. Where possible, the midtrabecular meshwork was treated, preferably at the superior half. After a mean follow up of 12.0 +/- 5.6 months, intraocular pressure (IOP) was controlled (less than or equal to 19 mm Hg) in five eyes (41.7%). YLT was associated with blood reflux during or after treatment in all successfully treated eyes. In eyes that failed, blood reflux could be detected in only two of seven eyes (28.6%). YLT failed to control IOP in all five eyes that had angle-recession for 360 degrees. Following YLT, IOP rose in two eyes (16.6%), minimal hyphema occurred in one eye, and temporary flare and cells developed in the anterior chamber in all eyes. Six eyes (50%) required glaucoma surgery (four had trabeculectomy and two had Molteno implant surgery). We recommend YLT only for selected cases of uncontrolled angle-recession glaucoma in which at least part of the trabecular meshwork by gonioscopy appears to maintain its anatomical structure, permitting penetration into Schlemm's canal.
We treated two patients in whom silicone oil pupillary block developed despite a patent inferior iridectomy. The clinical characteristics of this complication were a deep anterior chamber, specular reflexes from the iris surface, identification by biomicroscopy of aqueous trapped inferiorly in the vitreous cavity, and no convection currents in the anterior chamber. This complication may be prevented by early face-down positioning of the patient after the operation, and the avoidance of large, centrally located, inferior iridectomies. We recommend that the iridectomy be placed peripherally no larger than 2 mm and propose a new technique for breaking the silicone oil block, which was clearly successful in one of the patients.
We performed Molteno implant surgery in one eye each of 41 patients with uncontrolled glaucoma. Intraocular pressure was controlled (intraocular pressure less than or equal to 18 mm Hg) in 32 eyes (78%). The mean preoperative intraocular pressure was 40 +/- 13.2 mm Hg, whereas the mean postoperative intraocular pressure was 16 +/- 6.6 mm Hg. Patients were followed up for an average of 16 months after the operation. Visual acuity was unchanged in 23 eyes (56%), improved in nine eyes (22%), and poorer in nine eyes (22%). The major complications included shallow anterior chamber and hypotony in six eyes (14.6%), vitreous hemorrhage in two eyes (4.9%), retinal detachment in one eye (2.4%), and malignant glaucoma in two eyes (4.9%). Less grave complications included hyphema in four eyes (9.8%), peripheral choroidal effusion in 15 eyes (36.6%), obstruction of the tube in six eyes (14.6%), recession of the tube into the angle in two eyes (4.9%), erosion of the tube in one eye (2.4%), and Tenon's cyst formation in three eyes (7.3%).
Two cases of a brother and a sister with characteristic manifestations of Vogt-Koyanagi-Harada syndrome are presented. To the best of our knowledge, this is the first report of a typical appearance of Vogt-Koyanagi-Harada syndrome in two siblings.
A 56-year-old woman presented with orbital signs and symptoms suggestive of lacrimal gland tumor. An excised biopsy specimen was obtained and showed glandular tissue, which could be confused with lacrimal gland acini. Closer microscopic examination and immunohistochemical studies revealed a metastatic tumor of thyroid gland origin. Initially, there was no identifiable nodule in the thyroid, but 3 months later a thyroid nodule was found by ultrasound and radioisotope scan. The histopathologic appearance of the thyroid nodule was similar to that found in the orbit. This case demonstrates the usefulness of immunohistochemistry in establishing a diagnosis when the microscopic appearance is inconclusive.
A rare syndrome which includes VIth nerve palsy associated with ipsilateral Horner's pupil was foreseen by Parkinson and Johnston in the mid-seventies. They anticipated the occurrence of this syndrome on the basis of the unique anatomical relationships discovered by them in the cavernous sinus. The main finding consisted of very close proximity between the VIth nerve and a branch emerging from the carotid sympathetic plexus. Recently, several reports of this syndrome caused by a variety of pathologic processes in the cavernous sinus, proved that Parkinson and Johnston were correct. Since it is quite difficult to identify lesions in the cavernous sinus by X-ray or CT scan, the neuroradiologist should utilize special techniques. It is expected that the number of cases of this syndrome will soon increase, due to increasing familiarity with the syndrome and to improved imaging techniques.
A 62-year-old woman presented with acute angle closure glaucoma. After a poor response to conventional treatment the presenting signs were re-evaluated and a diagnosis of pseudotumour of the orbit was made. Treatment with oral steroids resolved both the glaucoma and the orbital pseudotumour. The presumed pathogenesis and literature are reviewed.
A rare case of thyroid carcinoma presenting as an orbital tumor is described. The diagnosis was made only through histopathologic examination of tissues removed during craniotomy. Thyroid scan confirmed the diagnosis. Thyroid carcinoma should be suspected in cases of orbital metastasis of unknown origin.