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Biomedical subjects

G Simon

Publications and source records attributed to G Simon.

At least 487 records · Page 27Linked to original sources
PubMedDate not supplied

Hypertension-producing factor in serum of hypertensive Dahl salt-sensitive rats.

To investigate whether serum in hypertensive Dahl salt-sensitive rats (S rats) contains a hypertensinogenic substance, we examined the effects of repeated injections of serum from such S rats on blood pressure (BP) and pressor responses. Serum was collected from either hypertensive or normotensive S rats (fed an 8% or 0.11% NaCl diet, respectively) and injected into uninephrectomized recipient S rats for 2 weeks (0.45 ml, twice a day, i.v.). Serum from hypertensive rats injected for 14 days significantly increased BP by 14 mm Hg (143 vs 129, p less than 0.05), pressor responses to angiotensin II (ANGII) by 45% (p less than 0.005), pressor responses to norepinephrine (NE) by 38% (p less than 0.025), and Na concentration in the aortic wall of recipient rats by 5.9% (p less than 0.05), compared to the effects of the injection of serum from normotensive S rats. These results imply that hypertensive S serum contains a hypertensinogenic substance and that this serum factor produces a mild hypertension in the recipient rats and also contributes importantly to the hypertension in donor S rats. Dahl salt-resistant rats (R rats) on either 8% or 0.11% NaCl had normal BP. Their sera produced no differences in BP or in pressor responses in recipient rats. Hence 8% NaCl, which produced no hypertension, also induced no hypertensinogenic serum factors in R rats. We sought to determine whether nephrectomy would alter these humoral factors. The BP averaged 139 mm Hg in rats receiving normotensive sham-nephrectomized S serum vs 154 in those receiving hypertensive sham-nephrectomized S serum, 15 mm Hg higher (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMedDate not supplied

Telephone counseling as an adjunct to antidepressant treatment in the primary care system. A pilot study.

CONTEXT: Many clinical and logistical barriers exist in the primary care model for treating adult depression. OBJECTIVE: To examine the feasibility and clinical effects of a telephone counseling and medication monitoring program for adults starting treatment for depression in primary care. DESIGN: Pilot study with a contemporaneous control group. SETTING: Group Health Cooperative, an HMO serving more than 450,000 persons in western Washington. PATIENTS: Twenty-eight adult primary care patients starting antidepressant treatment (telephone counseling group) were compared with 94 patients receiving usual care (control group). INTERVENTION: Telephone counseling participants received written educational materials addressing depression, followed by six weekly counseling and support sessions delivered over the telephone by a master's-level therapist. The intervention used the transtheoretical model of behavioral change and cognitive-behavioral strategies to enhance self-monitoring, self-management, and coping skills. DATA SOURCES: Telephone interviews and computerized pharmacy and visit records. OUTCOME MEASURES: Participation rate and retention, Hopkins symptom checklist depression scores, medication adherence and dose thresholds, and visits made for depression treatment. RESULTS: Ninety-three percent of telephone counseling participants contacted agreed to participate, and 92% completed the intervention. Telephone counseling patients showed significantly lower depressive symptoms than did control group patients at 3-month follow-up (0.89 vs. 1.13) and 6-month follow-up (0.79 vs. 0.95; P = 0.03). Telephone counseling patients were twice as likely to adhere to antidepressant medication with adequate dose thresholds (25% vs. 13%) and half as likely to meet criteria for major depression than were control group patients across time (8% vs. 16%), although these differences were not statistically significant. Total outpatient visits made for depression treatment between groups across time did not differ. Overall program cost per patient was estimated at about $150. CONCLUSIONS: A telephone counseling and medication monitoring intervention was well accepted by adult patients starting treatment for depression in primary care. The intervention seems to significantly improve depression outcomes without affecting the number of visits for treatment of depression.

Adult↗
PubMedDate not supplied

[Tracheal injury].

Explore the source record for details and available documents.

Adult↗
PubMedDate not supplied

Health-related quality of life in older people using benzodiazepines: a cross-sectional study.

Aim of this study is to investigate the QoL older people making regular use of BDZ. All subjects aged 65-84 years attending their General Practitioners were invited to fill in a questionnaire about their consumption of BDZ and all the subjects consuming BDZ to fill in the Medical Outcome Measures Short Form-36 (MOS SF-36) and the Primary Care Evaluation of Mental Disorders (PRIME-MD) questionnaires. A total of 2,246 subjects used BDZ and 1,109 (49.4%) of them filled in the MOS SF-36 questionnaire. 1,005 of these participants also completed the PRIME-MD questionnaire (90.6%). The presence of sleep disorders and the characteristics of the BDZ used were not associated with any score in the MOS SF-36 questionnaire, whereas the Prime diagnosis was the most important predictor, since subjects with depression and/or anxiety had a lower mean score on each scale than subjects without disorders. Among a sample of Italian seniors taking BDZ, QoL was associated with the presence of anxiety and/or depression. Age, gender, education and the presence of cardiovascular diseases or stroke were associated with specific aspects of QoL, when anxiety and depression were controlled for.

Age Factors↗
PubMedDate not supplied

Modification, calibration, and comparative testing of an automated surgical keratometer.

A new digital surgical keratometer (SK-1, Canon Inc) designed to fit existing operating microscopes and provide quantitative measurements at a nominal 2.0- and 3.6-mm diameter optical zone of the central cornea was modified for single foot-switch operation by the surgeon. The instrument was tested against three calibrated steel spheres, an astigmatic test-jig, and compared with a standard clinical keratometer (CLC, A.O. Co) in two studies involving six eye bank eyes and five healthy human corneas. Assessed with the steel spheres, the SK-1 calibration error was -0.042 diopters at the 3.6-mm diameter and +0.207 D at the 2.0-mm chord, while it was -0.120 D for the CLC. With cylindrical power greater than 0.50 D, the astigmatic angle was accurate to +/- 1 degree. After correction for calibration error, the CLC readings on eye bank eyes were 1.00 D higher in average (range +0.45 to +1.90) than those obtained with the SK-1 which gave lower keratometric values at the 2-mm chord diameter (-0.254 D, range: +0.05 to -0.7). The human subject corrected readings at the 3.6-mm chord were within 0.137 D (range -0.09 to +0.41) from the CLC values. A mean corrected difference of +0.068 D (range -0.27 to +0.30) was found between the two chords. The SK-1 instrument was easier to use than the CLC. A more accurate calibration and the addition of automated averaging and video display of readings as well as of a motorized Placido disc would further augment its clinical usefulness.

Calibration↗
PubMedDate not supplied

[5-fluorouracil treatment of acute pancreatitis and of pancreatic and duodenal fistulae].

In acute pancreatitis the mechanism involved in the auto-amplification of morbid phenomena can be suppressed in most of the cases by inhibiting the pancreatic secretion. This can also enhance the repair of pancreatic, duodenal and jejunal fistulae. On the basis of experimental studies carried out by Johnson, and on the clinical studies of Guttmann, as well as on original studies done by the authors, Ftorafur was included in the complex therapy of acute pancreatitis, and of pancreatic and duodenal fistulae. A group of 14 cases of acute pancreatitis, were treated. These included 5 necrotic-haemorrhagic pancreatitis, and 9 oedematous pancreatitis. The drug was given by continuous intravenous perfusion in doses of 1,200-1,600 mg per day, for a period of 6-12 days. In all the cases the clinical improvement of the patients as well as recovery of normal values of blood amylase were spectacular, and full recovery was achieved in all the cases. Ftorafur was also used in 3 cases of pancreatic fistulae, and in 2 cases of duodenal fistulae, and recovery was also achieved in a very short time. On the basis of this experience, although small, the authors recommend the introduction of Ftorafur in the complex therapy of acute pancreatitis, as well as in that of pancreatic and duodenal fistulae. Following administration of Ftorafur no adverse effects were noted, and in the doses mentioned above this drug did not delay the repair of surgical wounds.

Acute Disease↗
PubMedDate not supplied

[An experimental study of the action of 5-fluorouracil on the function and cytomorphology of the exocrine pancreas].

The authors have taken up previous studies by Martin (1969), and by Johnson (1973), and carried out an experimental study on white rats aimed at evaluating the morpho-functional changes of cells from the exocrine pancreas under the influence of 5-fluorouracil (Ftorafur), a cytostatic drug which is a general inhibitor of protein synthesis by cells. Ftorafur was injected in amounts of 2.3 mg/100 g of body weight, and a significant reduction was noted in the secretion of bicarbonates, amylase and lipase by the pancreas of the animals. Cytologic changes were also noted in the pancreatic tissue of these animals, indicating, on the one hand, a deficient protein and enzyme synthesis by the pancreatic cells, and a blocking of the mechanism of discharge of zymogen granules, on the other hand. The most intensive morpho-functional changes were noted following repeated administration of Ftorafur, probably due to the cumulative effects of this substance at the level of secretory pancreatic cells. The authors consider that 5-fluorouracil inhibits to a considerable degree the synthesis of pancreatic enzymes, and as such it can be used as a therapeutic means for the reduction of the external secretion of the pancreas.

Animals↗
PubMedDate not supplied

[Lonely pulmonary varices. Report of two new cases].

Authors report two new cases of lonely pulmonary varices, raising the number of lonely pulmonary varices to 34 and to 61 the number of pulmonary varices related in literature. In both cases the dilated veins were discovered by chance on a chest roentgenogram. The pulmonary angiogram has brought the diagnosis out. A recall of the clinical symptoms and radiological aspects shown off the importance of the pulmonary angiography and of a regular supervision of those patients. If some complications appear or if some shadows extend on chest roentgenogram, the surgical treatment might become necessary.

Female↗
PubMedDate not supplied

Biomechanical behavior of the cornea and its response to radial keratotomy.

BACKGROUND: Radial keratotomy reduces myopia by flattening the central cornea, but the mechanism remains a matter of controversy. In this article, we studied the biomechanical behavior of the cornea and its response to radial keratotomy. METHODS: A human cadaver eye model without corneal epithelium was used in this study. We studied the effects which varying intraocular pressure (IOP) and corneal hydration would have on the keratometric power of unoperated eyes and eyes following radial keratotomy. For nonoperated eyes, first, normal corneal hydration was maintained while the IOP was varied. Second, the IOP was maintained at a constant level of 20 mm Hg while the corneal hydration was changed. The effects of separately varying the IOP and corneal hydration of postoperative eyes following an eight-incision radial keratotomy were studied in a similar fashion. RESULTS: In the nonoperated eye, a very high IOP was associated with a general reduction of corneal astigmatism without significantly affecting the overall keratometric spherical equivalent refraction. A steepening change of less than 0.50 diopters (D) was obtained in all eyes when dehydrating the cornea from 700 +/- 50 microns (centrally) and 830 +/- 70 microns (peripherally), to 495 +/- 25 microns (centrally) and 655 +/- 45 microns (peripherally). Following radial keratotomy, changes in IOP within the physiological range were found to have minimal influence (< 0.50 D) on the radial keratotomy keratometric power. However, after hydrating the cornea with balanced salt solution for 30 minutes, we obtained a mean flattening of 10.00 D. When dehydrating these corneas with topical hyperosmotic solution over a period of 3.5 hours, the flattening reversed to near preoperative values. The change in keratometric power resulting from radial keratotomy was significantly modulated by varying the hydration state of the deepithelialized cornea: the greater the hydration, the flatter the central cornea; therefore, the unpredictable surgical outcomes and diurnal fluctuations observed after radial keratotomy may be affected by applying topical hyperosmotic agents. CONCLUSIONS: We hypothesize that the corneal stroma is an inelastic, anisotropic, layered collagen structure that distributes tensile stress unequally throughout its thickness as a function of the amount of hydration. IOP, within physiological levels, did not have a significant effect on corneal flattening.

Biomechanical Phenomena↗
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Noncontact laser photothermal keratoplasty. I: Biophysical principles and laser beam delivery system.

BACKGROUND: Thermal shrinkage of stromal collagen is known to produce changes in the corneal curvature. We designed a novel, noncontact laser beam delivery system to perform laser photothermal keratoplasty. MATERIALS AND METHODS: The instrument consisted of a pulsed holmium:YAG laser (2.10-micrometer wavelength, 250-microsecond pulse width, 5-hertz repetition rate) coupled via a monofilament fiber to a common slit-lamp microscope equipped with a polyprism, an adjustable mask, and a projection lens. The system projected an 8-spot annular pattern of infrared laser energy on the cornea to achieve a thermal profile within the stroma and to attain controlled, predictable collagen shrinkage. The system produced treatment patterns of 8 to 32 spots of 150 to 600 microns diameter in concentric rings, continuously adjustable between 3 and 7 mm. The versatility of the system in creating different treatment patterns was tested on thermal paper and human cadaver eyes. RESULTS: A uniform beam profile and different treatment patterns for myopia, hyperopia, and astigmatism were obtained. Myopic correction of 6.00 diopters was demonstrated on cadaver eyes. Corneal topography documented corneal flattening (> 6.00 D) with the following treatment parameters: each spot size on the cornea = 300 microns, radiant exposure of each spot = 18.0 J/cm2, number of pulses = 1, diameter of the treatment ring = 3 mm. CONCLUSIONS: Noncontact slit-lamp microscope laser delivery system for laser photothermal keratoplasty provides flexible and precise selection of laser treatment parameters. It may improve the efficacy of the procedure.

Cadaver↗
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Noncontact laser photothermal keratoplasty. II: Refractive effects and treatment parameters in cadaver eyes.

BACKGROUND: Noncontact laser photothermal keratoplasty may provide a new alternative for the treatment of myopia, hyperopia, and astigmatism. The purpose of this article is to study the refractive effect that laser photoablation keratoplasty is capable of producing on a normal human cadaver cornea, including the relationship between the keratometric changes and laser treatment parameters. METHODS: The human cadaver eyes were treated with a holmium laser (pulsed Ho:YAG, 2.10 microns, 250 microseconds) coupled to a maskable, polyprismatic delivery system mounted on either an optical bench or a slit-lamp microscope. Using a topographic videokeratography system, we first investigated the refractive effect that noncontact laser photothermal keratoplasty would produce on a normal cadaver cornea. We then studied the keratometric changes produced by different radiant exposure levels at a fixed treatment pattern, as well as by different treatment patterns at a fixed radiant exposure level. Finally, we studied the possible therapeutic application of laser photothermal keratoplasty for correcting high postoperative astigmatism on a cadaver eye model. RESULTS: For the single-pulse 3-millimeter ring of eight-spot treatment, the keratometric power of the cornea initially increased with the radiant exposure and peaked at 26 J/cm2. The refractive effect was increased by projecting an additional set of eight spots equidistant between the first eight spots on the same diameter ring. Eighteen J/cm2 was the minimal radiant exposure required to produce consistent and predictable keratometric changes. The corneas were flattened using treatment patterns smaller than or equal to 3 mm in diameter and steepened using treatment patterns larger than or equal to 5 mm in diameter. A transition zone between 4 and 5 mm was observed in which minimal and unpredictable keratometric changes of the central cornea occurred. The surgically-induced astigmatism (> 10.00 D) was corrected by progressive laser photothermal keratoplasty treatments. CONCLUSIONS: Laser photothermal keratoplasty can acutely steepen and flatten the cornea in human cadaver eyes.

Astigmatism↗
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Noncontact laser photothermal keratoplasty. III: Histological study in animal eyes.

BACKGROUND: Laser photothermal keratoplasty has been studied as a potential refractive procedure. The purpose of this study is to investigate the histological response to various laser treatments including geometrical patterns, radiant exposure levels, and pulse numbers. MATERIALS AND METHODS: A noncontact laser photothermal keratoplasty system was used in this study. Epithelial and endothelial response to the laser photothermal keratoplasty annulus treatment pattern were studied on an owl monkey model with a 5-millimeter annulus ring pattern, 8 J/cm2, 25 consecutive pulses at 1 Hz. Epithelial and endothelial response to the laser photothermal keratoplasty spot pattern were then studied and compared on cat and rabbit models for safety monitoring. One pulse and five consecutive pulses of eight different radiant exposures (5.00 J/cm2 to 18.01 J/cm2) were applied on each cornea. A cadaver eye model was used to study the collagen shrinkage induced by the laser spot treatment following the same protocol as the cat and rabbit model. Finally, the biological healing response to the laser photothermal keratoplasty treatment with the optimal laser parameters obtained in our experiment was studied on the cat model. Five cats were treated by the laser photothermal keratoplasty procedure with eight spots on a 3-millimeter ring, 15.6 J/cm2, and 1 pulse. RESULTS: Epithelial and endothelial damage were observed after annulus treatment on an owl monkey's cornea at 8 J/cm2, 25 pulses, and after spot treatment on cat and rabbit corneas at 18.01 J/cm2, five pulses. No endothelial damage was observed on cat corneas for the single pulse treatment at 18.01 J/cm2. For the tissue shrinkage study, no laser photothermal keratoplasty lesion could be detected for a radiant exposure setting below 10.26 J/cm2. Histological cross-sections showed that the five-pulse treatment reached the endothelial layer at a radiant exposure of 13.4 J/cm2, while no single pulse treatment reached the endothelium for the radiant exposure range (5 J/cm2 to 18 J/cm2) studied. The cat model showed that the laser-induced mechanical octagonal stress-lines by collagen shrinkage were maintained after 3 months. The histological sections across the lesion showed a denser keratocyte population indicating scar formation. CONCLUSION: The volume of collagen shrinkage, its location, and its geometrical shape can be accurately and precisely controlled by a 2.10-micrometer Ho:YAG laser coupled to an optical delivery system.

Animals↗