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Biomedical subjects

S Scheer

Publications and source records attributed to S Scheer.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Change in refraction and topography after penetrating keratoplasty suture removal].

PURPOSE: To study the refractive and topographic modifications induced by penetrating keratoplasty suture removal. METHODS: We prospectively studied 80 corneas from 80 patients who had undergone penetrating keratoplasty. All of the eyes were examined before and after all sutures were removed, respectively at 10.9 5.1 months and 21.5 9.6 months after keratoplasty. Subjective refraction, best spectacle-corrected visual acuity (LogMAR units), keratometry, and corneal topography using the EyeSys 2000((R)) device (axial tangential and refractive power) were recorded. Topographies were classified according to the pattern (Bogan classification) and the asphericity shape (prolate and oblate). RESULTS: Best spectacle-corrected visual acuity (Log MAR units) increased significantly after suture removal (1.1 1.9 lines, plt; 0.001). Suture removal decreased the subjective cylinder (5.01 D 2.06 with suture, 4.11 2.08 without suture; p=0.009). The change in subjective cylinder correlated with the change in topographic pattern(s)=0.67 p<0.001). Conversely to the "bow tie" patterns, the other topographic patterns were more frequent after suture removal. The change in visual acuity was essentially explained by the change in subjective cylinder(s)=0.40 p=0.002). The average central corneal power decreased significantly after suture removal by 0.83 to 1.81 D (p<0.001), whereas the subjective spherical equivalent increased (hyperopization) (-4.07D 3.73 with suture, -3.48 3.40 without suture; p=0.02). The change in central corneal power significantly correlated with the change in subjective spherical equivalent (r(s)()>0.30 plt; 0.001). The corneal power of the mid-periphery did not significantly change after suture removal. Suture removal significantly modified the asphericity shape distribution. (majority of prolate shape with suture, majority of oblate shape without suture, p<0.001). CONCLUSION: Keratoplasty sutures induce a central bulge in the corneal graft. Suture removal induces a decrease in the subjective cylinder and it increases the subjective spherical equivalent (hyperopization) through a decrease in the central corneal power. Suture removal modifies the corneal topographic pattern and shape. Visual acuity improvement after suture removal is mainly explained by the decrease in subjective astigmatism.

Adolescent↗
PubMed2001

[Ocular biometric measurements with a slit-lamp method (Orbscan)].

PURPOSE: To evaluate the accuracy and reproducibility of the biometric measurements obtained with the Orbscan((R)) device in normal eyes. METHODS: Anterior chamber depth, axial length, and corneal diameter were studied in 50 normal eyes of 25 patients using the Orbscan((R)) device and A-Scan ultrasonography. For each eye, two exams were done successively and reproducibility was calculated by analyzing the difference between both measurements. RESULTS: The reproducibility of anterior chamber depth and corneal diameter measurements obtained by Orbscan((R)) was high (respectively 0.721.25% and 0.831.40%). The anterior chamber depth measurements by Orbscan((R)) and A-Scan ultrasonography were strongly correlated (rs=0.92;p<0.001). The axial length measurement obtained with the Orbscan((R)) device was less reproducible (3.554.11%). For the axial length, the Orbscan((R)) measurements and A-Scan ultrasonography measurement was poorly correlated. (rs=0.64; p<0.001). CONCLUSION: The anterior chamber depth measurement obtained with the Orbscan((R)) device showed high reproducibility and it was strongly correlated with the measurement obtained by A-Scan ultrasonography. Axial length measurement obtained with the Orbscan((R)) device was less reproducible and poorly correlated with the A-Scan ultrasonography measurement. It was not relevant for clinical application.

Adult↗
PubMed2000

Regulation of human corneal epithelial cell proliferation and apoptosis by dexamethasone.

PURPOSE: To investigate whether human corneal epithelial cells express the glucocorticoid receptor (GR) and to assess the influence of dexamethasone (DEX) on these cells. METHODS: Human corneal epithelial cells were cultured in medium supplemented with various concentrations of DEX (ranging from 10(-10) to 10(-4) M). Cell proliferation was analyzed by 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfop henyl) -2H-tetrazolium inner salt (MTS) assay at 2, 4, and 6 days of culture. Apoptosis was studied by nucleus labeling using a fluorescent dye and immunostaining by APO 2.7 at 6 days of culture. GR mRNA was detected in corneal epithelium and cultured corneal epithelial cells by means of reverse transcription-polymerase chain reaction (RT-PCR). Immunocytochemical staining of the epithelial cells was performed with a monoclonal anti-human GR. RESULTS: RT-PCR and immunocytochemistry showed the expression of GR (mRNA and protein) in corneal epithelial cells. DEX significantly increased corneal epithelial cell proliferation with concentrations ranging from 10(-10) to 10(-6) M, with a maximum effect at 10(-7) M (P < 0.005). However, DEX also induced apoptosis of cultured corneal epithelial cells at any concentration used. CONCLUSIONS: These results indicate that human corneal epithelial cells express the GR and proliferate in response to DEX stimulation which also induces corneal epithelial cell apoptosis.

Apoptosis↗
PubMed1999

Combination antiretroviral therapy and incidence of AIDS-related malignancies.

We evaluated recent trends in the incidence of AIDS-related malignancies using Cox proportional hazards analysis in 622 men with well-characterized dates of HIV seroconversion in the San Francisco City Clinic cohort. By the end of 1996, 182 men had been diagnosed with Kaposi's sarcoma (KS), and 45 men had been diagnosed with lymphoma. The incidence of KS dropped from 3.5 to 0 per 100 person-years between 1993 through 1995 and 1996 (p = .07), whereas lymphoma incidence remained stable between these periods (1.4-1.8, p = .2). Combination antiretroviral therapy increased from 13% to 23% in 1993 through 1995 to 49% in 1996 and 79% in 1997. The decline in KS cannot be explained by earlier declines in HIV incidence, and concurrent increases in antiretroviral therapy suggests that control of viral replication may lead to a direct or indirect effect on KS pathogenesis. Failure to see such a trend for AIDS-related lymphoma may reflect inadequate follow-up time after widespread use of therapy or a need to treat earlier in the course of HIV infection to prevent HIV-associated lymphomagenesis.

AIDS-Related Opportunistic Infections↗
PubMed1999

The results of successful penetrating keratoplasty using donor organ-cultured corneal tissue.

BACKGROUND: The aim of this study was identification of predictive factors for postoperative visual acuity in patients with a clear organ-cultured graft and to analyze the change in visual acuity between 12 and 24 months after transplantation. METHODS: The study design was a prospective cohort study. A total of 342 consecutive penetrating keratoplasties using donor organ-cultured grafts, performed in 324 patients, were included. Visual acuity, graft thickness, and graft endothelial cell density were recorded in patients with clear transplants. RESULTS: At 24 months postoperatively, 25 (18.7%) of 134 patients had 20/200 or worse visual acuity and 66 (49.3%) had 20/40 or better visual acuity. Graft thickness took 1 month to decrease to normal values. A temporary graft thinning occurred at 6 months postoperatively, followed by recovery of normal graft thickness by 18 months. The average postoperative endothelial cell density was 1,533+/-598 cells/mm2 during the second year. The 24-month LogMAR (logarithm of minimal angle of resolution) visual acuity correlated with preoperative LogMAR visual acuity (beta=0.26, P=0.005), postoperative lens status (beta=-0.34, P=0.008), preoperative intraocular pressure (beta=0.50, P=0.020), and postoperative astigmatism (beta=0.17, P=0.040). Visual acuity (P=0.022) significantly improved between 12 and 24 months. Preoperative diagnosis (P < 0.0001) and postoperative lens status (P < 0.0001) significantly influenced the change in LogMAR visual acuity between 12 and 24 months. CONCLUSIONS: Donor variables do not influence the visual acuity results of penetrating keratoplasty using organ-cultured donor tissue, whereas they have a strong influence on graft survival and graft endothelial cell density. Visual acuity improves during the first 2 years after transplantation. After keratoplasty, organ-cultured corneal grafts undergo dramatic modifications of their thickness and probably of their transparency.

Cornea↗
PubMed1999

Feasibility and suitability of targeting young gay men for HIV vaccine efficacy trials.

We evaluated factors affecting the feasibility of including young high-risk HIV-negative gay and bisexual men in preventive HIV vaccine trials using data from the U.S. Centers for Disease Control and Prevention Collaborative HIV Seroincidence Study. Of 2189 men enrolled in this study, 17% were <25 years of age. HIV seroincidence was 4.2/100 person-years (95% confidence interval [CI], 2.6-7.0) in young men compared with 2.0/100 person-years (95% CI, 1.4-2.6) for older men. Compared with men 25 and older, young men were more likely to report several high-risk behaviors, to perceive themselves to be at risk for HIV infection, and to report that their risk behavior might be increased by participation in an HIV vaccine trial. The majority of both young men (69%) and older men (74%) expressed willingness in participate in HIV vaccine trials. Young men were less likely to answer questions about vaccine concepts correctly and were more likely to be lost to follow-up. Young gay and bisexual men are important candidates for future HIV vaccine trials, but they may need targeted approaches to recruitment, retention, education about trial concepts prior to enrollment, and behavioral interventions during the trial.

AIDS Vaccines↗
PubMed1999

Combination antiretroviral therapy and recent declines in AIDS incidence and mortality.

The reasons for recent declines in AIDS incidence and mortality may include advances in treatment, but these may be confounded by earlier declines in the incidence of human immunodeficiency virus (HIV) infection. To determine whether the declines in AIDS and mortality may, in part, stem from wider use of combination antiretroviral therapy, 622 HIV-positive men with well-characterized dates of seroconversion were followed. In this group, combination therapy came into widespread use in only 1996. In a Cox proportional hazards model, the 1996 calendar period was significantly associated with slower progression to AIDS (relative hazard [RH]=0. 19, 95% confidence interval [CI], 0.05-0.69, P=.01) and death (RH=0. 45, 95% CI, 0.21-0.95, P=.04). Declines in incidence of HIV infection, changes in HIV virulence, and end-point underreporting cannot fully explain the decline in AIDS and death in 1996. The introduction of combination antiretroviral therapy as the standard of care may already have had measurable effects.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Neutralization escape in human immunodeficiency virus type 1-infected long-term nonprogressors.

Neutralization-escape variants of human immunodeficiency virus type 1 (HIV-1) were sought in persons who had persistent low virus loads and who remained asymptomatic for at least 12-16 years of infection without antiretroviral therapy. Viruses were isolated from 3 persons at two or three time points during the course of infection and were assessed for neutralization by sequential autologous serum samples. Virus neutralization was poor or undetectable with contemporaneous autologous serum but improved with later serum samples for each person. In particular, later isolates resisted neutralization by autologous serum samples that neutralized an earlier isolate. Strain-specific neutralizing antibodies remained detectable for up to 4.2 years without diminishing in titer. The results demonstrate that neutralization-escape variants arise periodically in HIV-1-infected long-term nonprogressors.

HIV Antibodies↗
PubMed1999

Effects of penetrating keratoplasty suture removal on corneal topography and refraction.

PURPOSE: To study the refractive and topographic modifications induced by penetrating keratoplasty suture removal. METHODS: We retrospectively studied 50 corneas from 50 patients who had undergone penetrating keratoplasty. All of the eyes were examined before and after all sutures were removed at 10.8+/-4.7 months and 20.3+/-7.9 months after keratoplasty. Subjective refraction, best spectacle-corrected visual acuity (LogMAR units), and corneal topography (EyeSys 2000R device) were recorded. RESULTS: Suture removal decreased the subjective cylinder by an average of 0.91+/-2.32 D (p = 0.004) and modified the corneal topographic pattern (p = 0.03) and shape (p < 0.001) distribution. The change in subjective cylinder correlated with the variation of the steepest meridian power (r(s) = 0.46; p < 0.001). It correlated with the change in topographic pattern (r(s) = 0.59; p < 0.001). The subjective spherical equivalent increased (hyperopization) by an average of 0.61+/-2.24 D (p = 0.01). After suture removal, the prolate shape was less frequent, and the oblate shape was more frequent than before suture removal. Best spectacle-corrected visual acuity increased by an average of 0.8+/-2.0 lines (p = 0.004). The change in subjective cylinder correlated with the change in visual acuity (r(s) = 0.36; p = 0.006). CONCLUSION: Suture removal modifies the corneal topographic pattern and shape. It decreases the subjective cylinder and induces an hyperopization. Visual-acuity improvement after suture removal mainly is explained by the decrease in astigmatism. Suture removal seems particularly helpful in corneas with a bow-tie pattern.

Adolescent↗
PubMed1999

Epidemiologic determination of community-based nursing case management for stroke.

Efforts to control costs, especially those resulting from the 1997 Balanced Budget Act, have resulted in profound opportunities for futuristic community-based nursing care. A retrospective chart review was conducted on 1,992 stroke patients discharged from 15 Cincinnati hospitals from July 1, 1995, to June 30, 1996. Determinants and descriptors of stroke distribution were identified. This study shows how nurses can plan cost-effective care while maintaining quality through an epidemiologic assessment of patient, family, and community needs.

Aged↗
PubMed1999

[Effect of sodium hyaluronate administered at the end of penetrating keratoplasty on reepithelialization of the graft].

PURPOSE: To investigate the effect of sodium hyaluronate on reepithelialization time after penetrating keratoplaty. METHODS: We prospectly studied 56 consecutive penetrating keratoplasties. One group of patients (n = 22) received dexamethasone ointment at the end of surgery. The second group (n = 34) received sodium hyaluronate and topical dexamethasone. Postoperative reepithelialization time and graft central thickness were recorded. RESULTS: There was no statistical difference between both groups for epithelialization (4.6 + 3.2 days in the hyaluronate group and 4.4 + 2.3 days in the dexamathasone group) and for graft thickness at day one (710 + 85 microns for the former group and 713 + 84 microns for the latter group) and at day of reepithelialization (663 + 80 microns for the former group and 703 + 99 microns for the latter group). The epithelium aspect was different at the first postoperative day between both groups. CONCLUSION: The use of sodium hyaluronate at the end of penetrating keratoplasty improves the graft epithelium aspect at the first postoperative day, but it does not influence reepithelialization time. Further studies are needed to investigate the mechanism of sodium hyaluronate effect on corneal epithelium.

Aged↗
PubMed1999

[Comparison of EyeSys videokeratoscope algorithms in the evaluation of idiopathic and postoperative astigmatism].

PURPOSE: To compare the accuracy and reproducibility of the Eye Sys videokeratoscope algorithms for analyzing idiopathic and surgery-induced astigmatism analysis. METHODS: Refractive astigmatism, videokeratoscopy (axial, tangential and refractive power), autorefractometry, autokeratometry, and keratometry were recorded in 20 patients with idiopathic astigmatism, 40 patients who had undergone cataract surgery and 40 patients who had undergone penetrating keratoplasty. For each eye, 2 successive videokeratoscopy were recorded. RESULTS: Both cylinder and axis provided by the tangential algorithm are significantly less reproducible than the cylinder and axis provided by the axial and refractive algorithms (P < 0.001). Cylinders provided by the axial and refractive algorithms showed a stronger correlation with subjective cylinder (rs > 0.89; p < 0.001) than the cylinder provided by the tangential algorithm (rs = 0.66; p < 0.001). Both keratometric axis and autokeratometric axis showed the strongest correlation with subjective axis (rs > 0.92; p < 0.001). The accuracy and reproducibility were higher for the topographic "bow tie" patterns than for the other topographic patterns. CONCLUSION: The axial and refractive algorithms of the Eye Sys videokeratoscope are more accurate and reproducible than the tangential algorithm for analyzing idiopathic or surgery-induced astigmatism.

Algorithms↗
PubMed1998

CD40 ligand and IFN-gamma synergistically restore IL-12 production in HIV-infected patients.

IL-12 production in HIV-infected (HIV+) individuals is severely impaired after stimulation by bacterial products or T cell-dependent stimuli. Because CD40-CD40 ligand (CD40L) interactions are the major mechanism involved in the T cell-dependent activation of antigen-presenting cells, we investigated whether this pathway was functional in HIV+ donors. CD40 expression was increased on freshly isolated monocytes from HIV+ individuals compared to HIV donors. However, equivalent CD40 expression was obtained in the two groups after cytokine stimulation. Since CD40 expression was intact in HIV+ donors' cells, we determined whether IL-12 production could be restored by providing exogenous T cell-dependent stimuli, CD40L and IFN-gamma, at the time of bacterial stimulation. IL-12 production was not altered by CD40L alone, was increased by IFN-gamma, and was synergistically restored to normal values by IFN-gamma + CD40L. This combination was more efficient for enhancing IL-12 production than granulocyte-macrophage colony-stimulating factor + CD40L or neutralizing anti-IL-10 antibody + CD40L. CD40L did not affect IL-10 production, whereas IFN-gamma significantly decreased it. This study demonstrates that the defect in IL-12 production by leukocytes from HIV+ donors can be overcome in vitro if the interacting cells are provided with the right T cell-dependent co-stimuli.

Adult↗
PubMed1998

Donor organ cultured corneal tissue selection before penetrating keratoplasty.

AIMS: Donor organ cultured corneal tissue selection before penetrating keratoplasty is carried out by taking into account different variables. The objective was to identify preoperative variables which are significantly and independently associated with transplant outcome and should effectively be taken into account before transplantation. METHODS: 231 consecutive penetrating keratoplasties were prospectively studied using organ cultured tissue. Morphometric analysis of the donor corneal endothelium was performed before transplantation. Graft survival and endothelial cell density, during the second year following transplantation, were studied both at a univariate and multivariate level. RESULTS: Recipient age, recipient rejection status, and preoperative diagnosis significantly influenced graft survival. Graft survival was higher when using corneal tissue from donors older than 80 years. Postoperative endothelial density decreased with preservation time and coefficient of variation after preservation. It increased with endothelial cell density after preservation and deswelling time, and correlated with preoperative diagnosis. CONCLUSION: Organ cultured corneas with endothelial cell density after preservation < 2000 cells/mm2, and high coefficient of variation, may be discarded before transplantation. Corneas should be preserved for less than 3 weeks, and allowed to deswell before transplantation for 2 or 3 days rather than 1 day.

Adolescent↗
PubMed1994

A selective synthesis of 4-aminobiphenyl-N2-deoxyguanosine adducts.

A selective synthesis of N2-deoxyguanosine adducts derived from 4-aminobiphenyl (ABP) is described. The reactions of O2-trifluoromethylsulfonyl-O6-allyl-3',5'-O-bis(tert-butyldimethyl silyl)-2'- deoxyxanthosine with 3-amino-4-acetaminobiphenyl and 4-hydrazinobiphenyl, respectively, are the key steps. Successive removal of the protecting groups from the protected adducts leads to the free adducts 3-(deoxyguanosine-N2-yl)-acetyl-ABP and N-(deoxyguanosyl-N2-yl)-ABP, respectively.

Aminobiphenyl Compounds↗
PubMed1992

Impact of HIV infection on mortality and accuracy of AIDS reporting on death certificates.

To assess the impact of HIV infection on mortality and the accuracy of AIDS reporting on death certificates, we analyzed data from 6704 homosexual and bisexual men in the San Francisco City Clinic cohort. Identification of AIDS cases and deaths in the cohort was determined through multiple sources, including the national AIDS surveillance registry and the National Death Index. Through 1990, 1518 deaths had been reported in the cohort and 1292 death certificates obtained. Of the 1292 death certificates, 1162 were for known AIDS cases, but 9% of the AIDS cases did not have HIV infection or AIDS noted on the death certificate. Only 0.7% of the decedents had AIDS listed as a cause of death and had not been reported to AIDS surveillance. AIDS and HIV infection was the leading cause of death in the cohort, with the highest proportionate mortality ratio (85%) and standardized mortality ratio (153 in 1987), and the largest number of years of potential life lost (32,008 years). The devastating impact of HIV infection on mortality is increasing and will require continued efforts to prevent and treat HIV infection.

Abstracting and Indexing↗