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John Gardner

Publications and source records attributed to John Gardner.

10 recordsLinked to original sources
PubMed2006

Reproducibility of flap thickness with IntraLase FS and Moria LSK-1 and M2 microkeratomes.

PURPOSE: To compare flap thickness reproducibility of the femtosecond laser and two mechanical microkeratomes. METHODS: Flap thickness for all eyes was measured as the difference between the preoperative (day of surgery) full corneal thickness and post-flap creation central stromal bed thickness using ultrasonic pachymetry. Flap thickness values produced by three different microkeratome systems were compared for accuracy and reproducibility. RESULTS: For 99 flaps created using the IntraLase FS laser with an intended thickness of 110 microm, the mean achieved thickness was 119 +/- 12 microm (range: 82 to 149 microm). In 100 eyes treated with the Moria LSK-1 microkeratome with an intended flap thickness of 160 microm, the mean achieved thickness was 130 +/- 19 microm (range: 71 to 186 microm). In 135 eyes treated with the Moria M2 microkeratome with an intended flap thickness of 130 microm, mean thickness was 142 +/- 24 microm (range: 84 to 203 microm). The standard deviation and range of corneal flap thickness created with the IntraLase FS laser was significantly smaller than either mechanical microkeratome (P < .0001). CONCLUSIONS: When compared to two commonly used mechanical microkeratomes, mean achieved flap thickness was more reproducible with the IntraLase FS laser, reducing the comparative risk of overly thick flaps.

Cornea↗
PubMed2005

VA-Medicare dual beneficiaries' enrollment in Medicare HMOs: access to VA, availability of HMOs, and favorable selection.

This study examined the association between Veterans Administration (VA)-Medicare dual beneficiaries' HMO enrollment and factors including sociodemographics, access/attachment to VA, self-reported health status, and characteristics of Medicare HMO markets. The results showed that availability of Medicare HMOs and less access to VA care were the major predictors of VA-Medicare dual beneficiaries' HMO enrollment. Other significant predictors of HMO enrollment were age (65-69), having no college education, VA priority status (low income; less than 50 percent service disability). There was some evidence of favorable selection measured by self-reported health status. The identified HMO enrollment profile can position VA better in attracting and managing the care of these beneficiaries and in meeting potentially large shifts in their need for VA care if Medicare benefits or policies change markedly.

Aged↗
PubMed2004

Effect of limited DNA methylation reprogramming in the normal sheep embryo on somatic cell nuclear transfer.

Active demethylation of cytosine residues in the sperm genome before forming a functional zygotic nucleus is thought to be an important function of the oocyte cytoplasm for subsequent embryonic development in the mouse. Conversely, this event does not occur in the sheep or rabbit zygote and occurs only partially in the cow. The aim of this study was to investigate the effect of limited methylation reprogramming in the normal sheep embryo on reprogramming somatic nuclei. Sheep fibroblast somatic nuclei were partially demethylated after electrofusion with recipient sheep oocytes and undergo a stepwise passive loss of DNA methylation during early development, as determined by 5-methylcytosine immunostaining on interphase embryonic nuclei. A similar decrease takes place with in vivo-derived sheep embryos up to the eight-cell stage, although nuclear transfer embryos exhibit a consistently higher level of methylation at each stage. Between the eight-cell and blastocyst stages, DNA methylation levels in nuclear transfer embryos are comparable with those derived in vivo, but the distribution of methylated DNA is abnormal in a high proportion. By correlating DNA methylation with developmental potential at individual stages, our results suggest that somatic nuclei that do not undergo rapid reorganization of their DNA before the first mitosis fail to develop within two to three cell cycles and that the observed methylation defects in early cleavage stages more likely occur as a direct consequence of failed nuclear reorganization than in failed demethylation capacity. However, because only embryos with reorganized chromatin appear to survive the 16-cell and morula stages, failure to demethylate the trophectoderm cells of the blastocyst is likely to directly impact on developmental potential by altering programmed patterns of gene expression in extra-embryonic tissues. Thus, both remodeling of DNA and epigenetic reprogramming appear critical for development of both fertilized and nuclear transfer embryos.

Animals↗
PubMed2004

Suicide surveillance in the U.S. Military--reporting and classification biases in rate calculations.

The military has a well-defined population with suicide prevention programs that have been recognized as possible models for civilian suicide prevention efforts. Monitoring prevention programs requires accurate reporting. In civilian settings, several studies have confirmed problems in the reporting and classification of suicides. This analysis evaluated whether suicides were underreported or misclassified under accident or undetermined manner of death in the military system. We reviewed all 1998 and 1999 military deaths using official death reports and compared these data with additional sources, most importantly the DoD Medical Mortality Registry. We assessed for evidence of expressed suicidal intent and past psychiatric history among deaths classified as undetermined and accidents due to gunshot, overdose, drowning, falls, or asphyxia. Using sources other than official records, we found 17% more suicides than were reported, and an additional 4% of deaths that were suspicious for suicide. This study suggests that reporting and classification errors may account for 21% additional suicides in the military. These findings are comparable to rates seen in civilian studies and add to the literature regarding the problems inherent in using administrative death classification data for medical surveillance purposes.

Adult↗
PubMed2002

Feasibility and timing of prehospital administration of reteplase in patients with acute myocardial infarction.

BACKGROUND: In myocardial infarction patients undergoing thrombolysis, treatment delays negatively impact outcomes. This pilot study was conducted to determine the feasibility and timing of field administration of intravenous double bolus reteplase in patients with ST-elevation myocardial infarction. METHODS: Sixty three patients with symptoms and EKG changes consistent with acute myocardial infarction of less than six hours duration received the first bolus of reteplase before arriving at the emergency department. A second bolus of reteplase was given in the emergency department. Subsequent resolution of ST-segment elevation was measured. Mean time from symptom onset to paramedic dispatch, and paramedic arrivals to first bolus of reteplase were measured. The mean time from the first bolus of reteplase to heparin bolus in an emergency department was also measured. All patients with evidence of ST-elevation and suspected acute myocardial infarction gave consent for the thrombolytic therapy. There were no refusals of therapy among those candidates eligible for thrombolysis. RESULTS: The mean times from the first bolus of reteplase to heparin bolus in the emergency department was substantially longer than the in-field times. Resolution of ST-segment elevation was recorded in 52 of the 63 patients and the times of resolution ranged from five minutes after the first bolus dose to 190 minutes after the second bolus of reteplase. Resolution of ST-segment elevation and relief of pain occurred almost simultaneously. CONCLUSIONS: These results demonstrated that in-field administration of thrombolytic therapy is a viable option to reduce the delay from symptom onset to initiation of thrombolysis. They demonstrated that satisfactory resolution of ST-segment elevation can be recorded in the field. The reduction in mortality observed in this study is comparable to previously published studies on inpatients.

Adult↗
PubMedDate not supplied

Dual-system use: are there implications for risk adjustment and quality assessment?

The authors examined the implications of dual-system use for risk adjustment and quality assessment. The sample (n = 34 151) included all veterans dually enrolled in the Veterans Health Administration (VA) and the private sector in 1998 with (1) an inpatient discharge from either a VA or Medicare setting for 1 of 6 conditions/procedures and (2) inpatient and/or outpatient use in both the VA and private sector. The authors used the Diagnostic Cost Groups risk-adjustment system to obtain concurrent and prospective health status (relative risk scores) using veterans' Medicare diagnoses only, VA diagnoses only, and diagnoses from both systems. Both concurrent and prospective relative risk scores increased when diagnoses from both systems were used; the population's disease profile also was affected. The authors conclude that it is important to capture the true disease burden of the population by obtaining diagnoses from all health care systems providing care to facilitate meaningful comparisons of performance.

Aged↗
PubMedDate not supplied

My vision.

Explore the source record for details and available documents.

Blindness↗