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G Simon

Publications and source records attributed to G Simon.

At least 127 records · Page 7Linked to original sources
PubMed1994

Ultraviolet solid-state laser (213-nm) photorefractive keratectomy. In vivo study.

BACKGROUND: The pulsed ultraviolet 213-nm solid-state laser has been demonstrated as an alternative to the gas argon-fluoride 193-nm excimer laser for photorefractive keratectomy (PRK). The authors studied the clinical course and histopathologic changes occurring in rabbit corneas after PRK with a 213-nm solid-state laser. METHODS: The 213-nm output of neodymium:YAG frequency-quintupled laser was used to create 5-mm optical zone ablations in seven pigmented rabbit corneas. The radiant exposure was 250 mJ/cm2 delivered through a computer-controlled scanning delivery system with a spot size of 0.5 mm. The target ablation was 4.0 diopters with an estimated ablation depth of 40 microns. A clinical estimate of corneal epithelial healing and stromal haze was made at intervals over the 3-month study period. Animals were killed immediately after ablation, or at 10 days, 1 month, or 3 months after ablation. Corneal tissue was preserved for light microscopy and transmission electron microscopy at each study interval. RESULTS: All corneas re-epithelialized within 10 days postoperatively. Anterior stromal haze was clinically visible at 3 days, increased until approximately 1 month, and then gradually decreased over the succeeding 2 months. Residual subepithelial haze was visible at 3 months. Results of histopathologic study documented normal epithelium healing over time; the basement membrane retained its regular thickness and hemidesmosomes were abundant at 3 months. The anterior stroma had an increased number of fibroblasts at 10 days, many of which remained until 1 month. A mild, transient, cellular reaction occurred throughout the thickness of the stroma and the endothelium. CONCLUSION: Using the 213-nm ultraviolet solid-state laser with a scanning delivery system, PRK shows a similar clinical course and histopathologic findings to the 193-nm excimer PRK study in rabbits. It is a clinically viable procedure for refractive surgery and requires further human clinical trails to determine its efficacy.

Animals↗
PubMed1994

Paravaginal female adnexal tumor of probable wolffian origin.

Female adnexal tumor of wolffian origin (FATPWO) is a lesion that predominantly occurs in the broad ligament. Its occurrence in the right paravaginal area is rare; only one other case has been reported to occur at this site. The authors report a case of paravaginal FATPWO in a 20-year-old woman that recurred twice during a 5-year period. The microscopic and ultrastructural features of this lesion were identical to other cases of FATPWO reported in the literature. This tumor must be recognized, especially at this site, so that it is not confused with vaginal adenocarcinoma related to diethylstilbestrol exposure in utero.

Adenoma↗
PubMed1994

Captopril-stimulated renal vein renin measurements in the diagnosis of atherosclerotic renovascular hypertension.

The diagnostic utility of post-captopril renal vein renin (RVR) measurements was quantitated in 43 patients (mean age 62, range 41 to 77 years) undergoing aortography to rule out renovascular hypertension (RVHT), and then compared with that of pre-captopril RVR measurements. Four patterns of post-captopril RVR secretion were defined: 1) unilateral hypersecretion (stenotic/peripheral [S/P] > 2.0) and contralateral suppression (C/P) (< 1.25) (n = 12); 2) bilateral hypersecretion (S/P > 2.0, C/P > 1.25) (n = 14); 3) bilateral suppression (peripheral plasma renin activity [PRA] < 1.0 ng/mL/h) (n = 12); and 4) "normal" (RVR/PRA < 2.0 bilaterally) (n = 5). Using the radiologic findings as the definitive test, the sensitivity and specificity of post-captopril RVR measurements in detecting unilateral or bilateral renal artery stenoses (85% or greater of lumen) was 61 and 96%, and 92 and 90%, respectively, a significant improvement compared with those of pre-captopril RVR measurements (44 and 62%, and 17 and 93%, respectively). Post-captopril RVR measurements facilitated the diagnosis of both hypersecretion and, when present, contralateral suppression of renin, and therefore, are useful in the diagnosis of atherosclerotic RVHT, and in planning its treatment. However, confirmation by more extensive prospective studies, including treatment outcome, is needed.

Adult↗
PubMed1994

Autopotentiation of pressor responses by subpressor angiotensin II in rats.

The mechanisms whereby the continuous administration of initially subpressor doses of angiotensin II (ANG II) leads to pressor hyperresponsiveness and gradual development of hypertension were investigated. Male Sprague-Dawley rats (350 to 400 g) were given ANG II intraperitoneally, 200 ng/kg/min, for 24 h, 7 to 10 days, or 6 weeks. Vehicle-infused rats were controls. Pressor responses to incremental doses of ANG II, norepinephrine (NE), and serotonin were measured in chloralose-anesthetized rats, before and after neurohumoral blockade, and the main findings were confirmed in awake, free-moving rats with implanted catheters. Pressure responses to ANG II and NE were also measured in the isolated, pump-perfused mesenteric circulation of rats after 7 to 10 days of ANG II or sham infusion. Compared with control rats, there were no hemodynamic changes in ANG II-treated rats at 24 h. After 7 to 10 days of ANG II treatment, tail systolic blood pressure rose by 13 mm Hg (P < .01) and pressor responses to ANG II (P < .01) but not to NE or serotonin were increased. Pressor hyperresponsiveness was due in part to potentiation of vascular responses because pressure responses to ANG II (P < .002) but not to NE were also increased in the mesenteric circulation of ANG II-treated rats. By 6 weeks, mild hypertension was well established in ANG II-treated rats and pressor responses were increased to both ANG II (P < .05) and NE (P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

The torR gene of Escherichia coli encodes a response regulator protein involved in the expression of the trimethylamine N-oxide reductase genes.

Expression of the Escherichia coli torCAD operon encoding the trimethylamine N-oxide (TMAO) reductase system is induced by both TMAO and anaerobiosis. A torR insertion mutant unable to express the torA gene had previously been isolated. The torR gene was cloned and sequenced. It encodes a 25,000-Da protein which shares homology with response regulators of two-component systems and belongs to the OmpR-PhoB subclass. Overproduction of TorR mimics the presence of the inducer TMAO while the anaerobic control is unchanged, suggesting that TorR mediates only the TMAO induction. The overproduced TorR protein was purified to more than 90%. The torR gene is located just upstream of the torCAD operon, with an opposite transcription direction. The torR-torCAD intergenic region is unusual in that it contains four direct repeats of a 10-nucleotide motif. Part or all of these motifs could be involved in the binding of TorR. The gene encoding the sensor partner does not seem to be adjacent to torR, since the divergent open reading frame found immediately downstream of torR exhibits none of the features of a protein histidine kinase.

Amino Acid Sequence↗
PubMed1994

Stimulation of vascular glycosaminoglycan synthesis by subpressor angiotensin II in rats.

The vascular trophic effects of angiotensin II (Ang II) in small doses may precede its hypertension-producing effect, and de novo synthesis of components of extracellular matrix may be a requirement for Ang II-stimulated growth. In the present study, therefore, the incorporation of 35SO4 into glycosaminoglycans (synthesis) of aorta and bladder wall of young adult, male Sprague-Dawley rats was measured ex vivo after 48 hours of Ang II administration at two dose levels, 100 and 200 ng.kg-1.min-1 IP. Vehicle-infused rats served as controls. Compared with controls, systolic blood pressure was unchanged in rats receiving 100 ng.kg-1.min-1 Ang II and rose by 13 mm Hg (P < .05) in rats receiving the 200-ng.kg-1.min-1 dose. In Ang II-treated rats, glycosaminoglycan synthesis of the aorta was increased by 20% (P < .05) and 52% (P < .005) at the two dose levels, respectively. Glycosaminoglycan synthesis of bladder smooth muscle was also increased in Ang II-treated rats (P < .01), but the response was not dose dependent. By 7 to 10 days of Ang II administration (200 ng.kg-1.min-1), glycosaminoglycan synthesis of aorta returned toward baseline (P < .10, > .05). The rate of synthesis of subtypes of glycosaminoglycans in the aorta was proportionately increased by Ang II. The early occurrence, magnitude, and arterial pressure independence of Ang II-induced glycosaminoglycan synthesis suggest that restructuring of extracellular matrix may play an important role in both the trophic and hypertension-producing action of Ang II.

Amino Acid Sequence↗
PubMed1994

[Results of a 2-year animal experiment with reticulated polyethylene oxide intrastromal rings].

Gel Injection Adjustable Keratoplasty (GIAK) is a technique previously described by G. Simon for the correction of myopia. Following pachometry, a 0.8 mm wide, 80% deep linear incision is performed 2.5 mm from the apex. Using a guide, a 1 mm wide, 5 mm diameter annular spatula is introduced to dissect an interlamellar canal and the crosslinked polyethylene oxide hydrogel is injected with a modified 23 gauge needle. The biocompatibility to 13 PEO batches was studied on 21 albino rabbits (Follow up 15 to 135 days). In nineteen, the cornea remained perfectly transparent. Two animals presented an infection at POD 1. Histopathology showed no endothelial deterioration, no anomaly of the thickness or of the cellular morphology around the injected zone. However some mononuclear cells were noticed surrounding the hydrogel in some rabbits together with thinning of the corneal epithelium anterior to the injected zone. A pilot refractive study was conducted on 5 cats using 2 PEO gels. One cat developed an infection following surgery. A second developed an inflammatory response with corneal neovascularization at POD 8. Thus, these animals were not included in the follow-up study which ranged from 6 to 28 months. Immediately after surgery, the refractive effect, measured with the Canon SK-1 digital autokeratometer, was 5.22 +/- 0.46 D (SD) of flattening. The long term effect (26 months) of the GIAK procedure appears to be stable and safe when using sterile PEO gels made of highly purified materials.

Animals↗
PubMed1994

[Variation in drug prescription costs and general practitioners in an area of North-East Italy. The use of current data].

In this paper we analyse all General Practitioners (GP) prescriptions in a Friuli-Venezia Giulia area (North-eastern Italy). The sample included of 181 GPs and 242,564 patients with 1,191,122 prescribed items. The regional Health Data Base is the source of all data. Data analysis was performed according to the multiple regression and LISREL models. We assessed for all GPs the years of medical profession, patients listed, percent of patients exent from prescription rates, patients over 60, number of active compounds prescribed and related drug companies. Two factors, the number of active compounds prescribed and patients listed, significantly contributed to the multiple regression model. The model explained 56% of variation in prescribing pointing out the importance of those factors in influencing the cost per patient. LISREL model shows a causal chain going from the years of medical profession to cost per patient passing through the number of active compounds and drug companies related. In fact, the older the GP the less the cost per patient and number of active compounds used. A main finding is that the cost per patient is highly influenced by the number of different active compounds prescribed. As in other studies the percent of patients exent from prescriptions rates and aged over 60 are somehow fundamental in influencing the cost per patient. Finally we discussed models and literature on the issue.

Aged↗
PubMed1993

[Myofibrosis in childhood. Differential diagnosis in chest pain].

It is emphasised in connection with the differential diagnosis of chest complaints that after excluded the serious and urgent conditions, a searching for painful muscle bundles and trigger points at the characteristic locations in the muscles can explain the origin of the complaints. By finding of myofibrosis, other expensive or invasive diagnostic tests can be omitted and the patient gets rid off his or her claims.

Age Factors↗
PubMed1993

The SBASE protein domain library, release 2.0: a collection of annotated protein sequence segments.

SBASE 2.0 is the second release of SBASE, a collection of annotated protein domain sequences. SBASE entries represent various structural, functional, ligand-binding and topogenic segments of proteins [Pongor, S. et al. (1993) Prot. Eng., in press]. This release contains 34,518 entries provided with standardized names and it is cross-referenced to the major protein and nucleic acid databanks as well as to the PROSITE catalog of protein sequence patterns [Bairoch, A. (1992) Nucl. Acids Res., 20 suppl, 2013-2018]. SBASE can be used for establishing domain homologies using different database-search tools such as FASTA [Lipman and Pearson (1985) Science, 227, 1436-1441], FASTDB [Brutlag et al. (1990) Comp. Appl. Biosci., 6, 237-245] or BLAST3 [Altschul and Lipman (1990) Proc. Natl. Acad. Sci. USA, 87, 5509-5513] which is especially useful in the case of loosely defined domain types for which efficient consensus patterns can not be established. SBASE 2.0 and a set of search and retrieval tools are freely available on request to the authors or by anonymous 'ftp' file transfer from mean value of ftp.icgeb.trieste.it.

Amino Acid Sequence↗
PubMed1993

Laser scleral buckling for retinal reattachment.

The holmium:yttrium aluminum garnet (Ho:YAG) laser produces infrared light that is absorbed inside scleral tissues, which increases local temperature, thereby shrinking collagen and inducing a buckle effect. Scleral indentation was induced in ten cadaver eyes by shrinkage of scleral collagen fibers by using a pulsed solid-state Ho:YAG (2.1-microns) laser with fiberoptic delivery. The amount of laser-induced buckling effect is controlled by selecting laser treatment settings such as beam spot, radiant exposure, and number of pulses. With treatment using 11.3 +/- 1.2 J/cm2 of laser radiant exposure and five pulses, laser-induced scleral shrinkage affected only the external two thirds of the scleral tissue. No thermal damage or disruption was observed in subjacent retinal pigment epithelium, choroid, or retina. The coupling of two appropriately selected lasers may allow laser-induced scleral buckling and transscleral retinal photocoagulation by using the same laser probe for retinal reattachment.

Collagen↗
PubMed1993

[Statistical data on motor handicapped children, aged 0-18 years, based on a national survey].

A computer-based data processing was made at 6762 motor handicapped children. The data were obtained by questionnaires about the health status, educational, social level and rehabilitation of these children. The authors could state the use of therapeutical equipment, the further need for rehabilitation--specialists and the waiting list for the admission to institutions. The number of registered children was 2.4% of the specific population. The aim of the study was to promote the activity of local self governments, local--and national social security--and health authorities competent in the rehabilitation for the social integration of the Hungarian 0-18 years old motor handicapped persons.

Adolescent↗
PubMed1993

[Case histories of extranodal non-Hodgkin's lymphomas with primary gastrointestinal appearance].

Authors refer results obtained in 24 cases of primary NHL of gastrointestinal tract. These cases were observed in the period 1981-1990. All cases can be included as primary extranodal lymphomas satisfying criteria of the literature. Sixty-six per cent (16/24) had a gastric localization half cases were centrocytic-centroblastic lymphomas followed by immunoblastic, centroblastic, follicular centrocytic-centroblastic and lymphocytic-well-differentiated. In intestinal localisation (34% of cases), the most represented was lymphocytic poor-differentiated, followed by mixed centrocytic lymphoma. Therapeutic strategy was: surgery in all patients followed by chemotherapy (CHOP 14/24) or by radiotherapy plus chemotherapy (8/24). Surgery alone was adopted in 2 out 24 patients. Patients who received radiotherapy plus chemotherapy had a sandwich treatment (CVP = 4/8, CHOP = 4/8) consisting of splint course of 3 cycles followed by radiotherapy and completed with other 3 drugs cycles. Sixteen out 24 patients were valuable (4 patients were lost during the follow-up due to problems other than the disease; 4 patients are still under treatment). In the 16 valuable patients we had a complete remission (CR) with a median free-disease survival of 82 months (range: 12-116 months) by means of the primary treatment. Four out 16 patients relapsed. In these patients the free-disease survival was range 8-108 months. All patients reached a second CR by means of chemotherapy (CCNU + VIP16) or radiotherapy. No cases of second tumor insorgence was observed.

Adult↗
PubMed1993

Alternating and intermittent regimens of zidovudine and dideoxycytidine in patients with AIDS or AIDS-related complex.

OBJECTIVE: To determine whether alternating regimens consisting of zidovudine and 2',3'-dideoxycytidine (ddC) reduce the toxicity and maintain or increase the antiretroviral effect associated with each drug alone. DESIGN: An unblinded, randomized (phase II) clinical trial in which seven treatment regimens were compared. SETTING: Outpatient clinics of 12 AIDS Clinical Trials Units. PATIENTS: One hundred thirty-one patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex and serum p24 antigenemia (> or = 70 pg/mL). INTERVENTION: Treatments included weekly or monthly alternating zidovudine (200 mg every 4 hours) and ddC (0.01 or 0.03 mg/kg body weight every 4 hours); weekly intermittent zidovudine, 200 mg every 4 hours, or ddC, 0.03 mg/kg every 4 hours; and continuous zidovudine. MEASUREMENTS: Toxicity, CD4 cell counts, serum p24 antigen levels, and clinical end points. Data were analyzed for the first 48 weeks of therapy (median follow-up, 40 weeks). RESULTS: Hematologic toxicity was significantly less frequent in patients who received zidovudine therapy every other week (11% to 15%) or every other month (11% to 14%) than in those who received continuous zidovudine therapy (33%) (P < 0.02). Weekly alternating therapy with zidovudine and ddC, 0.03 mg/kg, or intermittent therapy with ddC, 0.03 mg/kg, produced high rates of peripheral neuropathy (41% and 50%, respectively). Neuropathy occurred in 10% to 21% of patients in the other three alternating-therapy limbs and in 17% of patients receiving zidovudine alone (intermittently or continuously). Initial increases in CD4 cell counts were sustained in three alternating-therapy limbs, but counts returned to baseline by week 28 in the remaining limbs. The median weight gain at week 48 was significantly greater in patients treated with alternating regimens (0.9 to 3.8 kg) compared with those treated with continuous zidovudine therapy (-0.7 kg) (P = 0.008). Patients treated with alternating regimens and those treated with continuous zidovudine had similarly sustained decreases in p24 antigen levels. CONCLUSIONS: These findings suggest that alternating therapy with zidovudine and ddC reduces the toxicity associated with each drug alone while maintaining strong antiretroviral activity.

AIDS-Related Complex↗
PubMed1993

Keratotomy for astigmatism using an arcuate keratome.

We describe a new system for performing transverse arcuate corneal incisions for the correction of astigmatism. The instrument consists of a conical housing with suction and/or friction fixation to the limbus and two micrometric diamond knives mounted on a carrier that can be rotated by a gear mechanism. The depth, length, and location of the incisions can be predetermined. Light microscopy of donor eye corneas documented the achieved incision depth. One sweep at normal speed produced an incision depth 28% less deep than the preset depth. One sweep at low speed achieved depths of approximately 100% of the knife setting. Variability from one incision to another in the same cornea was related to blade sharpness. We report successful use of the instrument in five consecutive eyes with naturally occurring astigmatism.

Adolescent↗
PubMed1993

Ultraviolet solid-state laser (213-nm) photorefractive keratectomy. In vitro study.

BACKGROUND: Replacing the gas argon fluoride (193 nm) excimer laser with a solid-state laser source in the far-ultraviolet spectrum region would eliminate the hazards of a gas laser and would reduce its size, which is desirable for photorefractive keratectomy. The authors investigated corneal reshaping using a frequency-quintupled (213 nm) pulsed (10 ns) neodymium:YAG laser coupled to a computer-controlled optical scanning delivery system. METHODS: A 250 +/- 15-mJ/cm2 radiant exposure was used to ablate a 5-mm optical zone in human cadaver eyes and rabbit eyes. The 213-nm laser pulses were delivered through and shaped by a computer-controlled optical scanning delivery system, producing a 0.5-mm spot with a quasi-Guassian energy distribution on the cornea. Corneal surface changes were documented by computer-assisted corneal topography. Light microscopy, scanning electron microscopy, and transmission electron microscopy were performed to examine the effects on corneal surface quality and cellular components. RESULTS: Corneal topographic measurements showed myopic corrections ranging from 2.3 to 6.1 diopters. Results of postoperative examination with the slit lamp and operating microscope demonstrated a smoothly ablated surface without corneal haze. Histologic results showed a smoothly sloping surface without recognizable steps. The surface quality and cellular effects were similar to that of previously described excimer photorefractive keratectomy. CONCLUSION: The authors demonstrated that an ultraviolet (213-nm) solid-state laser coupled to an optical scanning delivery system is capable of reshaping the corneal surface with smooth transition. The scanning beam delivery system may offer the advantage of producing spatially resolved, customized, aspheric corrections to optimize the quality of vision after photorefractive keratectomy.

Animals↗
PubMed1993

The SBASE domain library: a collection of annotated protein segments.

SBASE is a database of annotated protein domain sequences representing various structural, functional, ligand binding and topogenic segments of proteins. The current release of SBASE contains 27,211 entries which are provided with standardized names in order to facilitate retrieval. SBASE is cross-referenced to the major protein and nucleic acid databanks as well as to the PROSITE catalog of protein sequence patterns [Bairoch, A. (1992) Nucleic Acids Res., 20, Suppl., 2013-2118]. SBASE can be used to establish domain homologies through database search using programs such as FASTA [Lipman and Pearson (1985) Science, 227, 1436-1441], FASTDB [Brutlag et al. (1990) Comp. Appl. Biosci., 6, 237-245] or BLAST3 [Altschul and Lipman (1990) Proc. Natl. Acad. Sci. USA, 87, 5509-5513], which is especially useful in the case of loosely defined domain types for which efficient consensus patterns cannot be established. The use of SBASE is illustrated on the DNA binding protein Brain-4. The database and a set of search and retrieval tools are freely available on request to the authors or by anonymous 'ftp' file transfer from < ftp.icgeb.trieste.it >.

Amino Acid Sequence↗