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Biomedical subjects

M E Yablonski

Publications and source records attributed to M E Yablonski.

54 records · Page 3Linked to original sources
PubMed1981

Ocular and systemic responses to water soluble material derived from Cannabis sativa (marihuana).

A water soluble material, isolated from Cannabis sativa, has been tested in albino and pigmented rabbits and rhesus monkeys for both ocular and systemic effects. Intravenous administration produced a dose-related fall in intraocular pressure in both albino and pigmented rabbits with concentrations as low as 0.005 mg/animal being effective, but no response was found in monkeys. High concentrations (0.2 to 1 mg/animal) induced a hypertensive phase in intraocular pressure prior to the ocular hypotension; higher concentrations (2 or 5 mg/animal) also induced antidiuresis and general relaxation. Tachyphylaxis was found to repeated daily injections. Alpha and beta-adrenergic antagonists caused some reduction of the hypertensive phase but had no effect on the hypotensive phase. Superior cervical ganglionectomy did not influence the time course of the intraocular pressure response. Indomethacin inhibited the hypertensive intraocular pressure phase but was ineffective against the hypotensive phase. Systemic blood pressure was unchanged following intravenous administration of 0.2 mg material/animal. Aqueous tumor protein concentration was increased at both 1 and 6 hours after intravenous administration, becoming greater at the later time. Aqueous humor turnover rate was substantially reduced reaching a minimum 8.75 hours after administration. Topical administration was ineffective in eyes when the epithelium was removed in rabbits with and without pretreatment with aspirin. Neither gastric nor suppository administration of large quantities (10 mg or greater) of material had any influence on intraocular pressure.

Adrenergic alpha-Antagonists↗
PubMed1980

Prognostic significance of optic disk cupping in ocular hypertensive patients.

The stereoscopic photographs of 102 patients with increased intraocular pressure (IOP) and normal visual fields were graded for cup:disk ratio. All patients were followed up for a five-year period, during which time 27 patients developed glaucomatous visual field loss and 75 patients did not. The patients who subsequently developed glaucomatous visual field loss had significantly larger cup:disk ratios than did the patients who did not develop glaucomatous visual field loss. Patients with a mean IOP greater than or equal to 28 mm Hg and a vertical contour cup:disk ratio greater than or equal to 0.6 had a 100% incidence of the development of glaucomatous visual field loss as compared to a 2% incidence in those with a mean IOP less than 28 mm Hg and a vertical cup:disk ratio less than 0.6. Disk:cup asymmetry and progressive increase in the area of the disk occupied by the cup was more common in the group that developed glaucomatous visual field loss.

Aged↗
PubMed1980

Oxygen lowers intraocular pressure.

A significant decrease in intraocular pressure was demonstrated in 14 patients as atmospheric pressure was increased at intervals of 0.5 atmospheric pressure up to 3 atmospheres within a hyperbaric chamber. Nine of these patients had the identical protocol repeated in room air at atmospheric pressure without a significant change in intraocular pressure. Administration of 100% O2 at 15 L/min by partial rebreathing face mask to these patients using the same protocol at atmospheric pressure resulted in a significant decrease in intraocular pressure. The results in the oxygen and hyperbaric groups were not statistically different. While in the hyperbaric chamber, scleral rigidity increased uniformly, outflow facility decreased significantly, and keratometry readings remained unchanged. A significant decrease in intraocular prssure occurred in 20 rabbits that received 100% oxygen by partial rebreathing face mask for 180 minutes. Arterial blood gases were obtained at 0.90, and 180 min in seven rabbits. The pH and pCO2 did not change significantly; however, pO2 was markedly elevated. Increased oxygen concentration was felt to be responsible fot the decrease in intraocular pressure and the changes in other parameters observed in patients and rabbits.

Animals↗
PubMed1979

Timolol maleate: efficacy and safety.

A randomized, double-masked trial of various concentrations of timolol maleate ophthalmic solution (0.1%, 0.25%, 0.5%, and 1.0%) vs placebo demonstrated that all concentrations of timolol effectively lowered intraocular pressure (IOP). A 0.5% solution of timolol was as effective in reducing IOP as the 1.0% concentration. Blood pressure, visual acuity, and pupillary diameter were not altered significantly by any concentration of timolol tested during this study. There was a dose-dependent decrease in resting pulse rate with increasing concentrations of timolol. No objective signs of drug intolerance were found on external ocular examination, nor were any subjective symptoms elicited on questioning the subjects. Timolol applied topically twice daily in concentrations of 0.1% to 0.5% appeared to be an effective and safe ocular hypotensive agent.

Adult↗
PubMed1978

Cataracts induced by topical dexamethasone in diabetics.

Eleven diabetic patients were treated with unilateral topical dexamethasone for 14 to 36 months in an attempt to control their retinopathy. Cataracts developed in the treated eye of nine patients, compared with only one cataract in an untreated eye.

Administration, Topical↗
PubMed1978

A new fundus lens ophthalmodynamometer.

I devised a new ophthalmodynamometer by means of which a measured force is applied to a fundus lens, while the disk vessels are viewed at the slit-lamp microscope. In my hands, the new device was superior to the Bailliart ophthalmodynamometer when tested in normal volunteers. With the fundus lens ophthalmodynamometer, the diastolic end point differed between the two eyes by a mean of 2.3%, compared to 6.4% with the Bailliart. The new device showed a better correlation with systemic diastolic blood pressure than did the Bailliart instrument. The effect of intraocular pressure on the reading with the fundus lens device was significant, although variable.

Adult↗
PubMed1977

Dipivefrin use in patients with intolerance to topically applied epinephrine.

Twelve patients who had previously demonstrated an intolerance to topically applied epinephrine received dipivefrin 0.1% in one eye and epinephrine 2% in the other eye. An adverse reaction occurred in only one eye (8%) receiving dipivefrin, but in ten (83%) on epinephrine. Topical dipivefrin 0.1% proved useful for lowering intraocular pressure in patients intolerant to topically applied epinephrine.

Administration, Topical↗
PubMed1977

Mechanism of production of intestinal secretion by negative luminal pressure.

The relationships between luminal hydrostatic pressure and fluid transport by dog jejunum in vivo studied as a sheet in the Wells clamp were compared with quantitative predictions from a model proposed for the mechanism of the secretion produced by elevated venous pressure. According to the model, the secretion produced by increasing venous pressure and the secretion produced by negative luminal pressure are both passive filtrates contingent on a transepithelial pressure of a few centimeters of H2O. We consider that the agreement between the observed and predicted responses to luminal pressure provides strong support for the model. In particular, a) the observations displayed a predicted gross asymmetry in rates of fluid transfer with isotonic fluids depending on whether the luminal pressure was positive or negative; b) the observed magnitude of the negative luminal pressure required for the onset of secretion agreed with predictions; and c) the secretion contained significant amounts of protein at about 25% of the plasma concentration.

Animals↗
PubMed1976

Mechanism of production of intestinal secretion by elevated venous pressure.

A study was carried out to elucidate the physiological mechanisms responsible for the intestinal secretion produced by venous pressure elevation. In dogs, measurements were made of the rate and composition of small intestinal secretion, rate of flow and composition of intestinal lymph, plasma composition, and mucosal water content, all in response to elevations of intestinal venous pressure. Venous pressure elevations above a threshold value of 30-35 cm H2O produce secretion at a rate of approximately proportional to the value of the pressure minus the threshold value. Above the threshold value, there were large increases in the rates of lymph flow and net sustained transcapillary filtration. These rates were also roughly proportional to the incremental venous pressure. It is concluded that intestinal secretion produced by elevated venous pressure is almost surely secretory filtration, a passive process with the driving force for secretion an increase in mucosal tissue fluid pressures to values of only some 4-6 cm H2O. The increased tissue fluid pressure not only provides the driving force but also produces an increase in the hydraulic permeability of the epithelium without which the driving force would be ineffective. The transepithelial channels are large enough to permit insulin to pass freely and even plasma protein to pass in large amounts, and hence are most probably intercellular. Secretory filtration probably represents a general pathophysiological response of transporting epithelia to elevated tissue fluid pressure. It is proposed that the threshold value for secretion and associated changes is explained by dilution of the tissue fluid protein colloid osmotic pressure in a small subepithelial, juxtacapillary compartment.

Animals↗
PubMed1975

A new portable applanation tonometer.

A portable applanation tonometer consisted of a Goldmann applanation doubling prism mounted on a dynamometer. Results obtained on 100 consecutive eyes showed a good correlation with the standard slit-lamp mounted applanation tonometer. This portable tonometer is small and easy to use, utilizing the same end point as the standard Goldmann tonometer. In addition, the patient may assume almost any position.

Evaluation Studies as Topic↗
PubMedDate not supplied

A retrospective study of the effects of laser suture lysis on the long-term results of trabeculectomy.

We retrospectively examined the effects of laser suture lysis on the long-term results of initial trabeculectomies in 130 consecutive eyes that had an intraocular pressure greater than 21 mm Hg during the first 4 postoperative weeks. After the high intraocular pressure was noted, 46 eyes underwent laser suture lysis; the other 84 did not. The 2-year cumulative probability of success in the laser suture lysis group was .84 and, in the control group, .82 (P > .05). Intraocular pressures in the two groups 1 and 2 years after trabeculectomy were similar. Laser suture lysis had no discernible effect on the long-term success rate of trabeculectomy in these patients.

Adolescent↗