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Biomedical subjects

Fei Yu

Publications and source records attributed to Fei Yu.

At least 37 records · Page 2Linked to original sources
PubMed2006

Health effects in children aged 3-6 years induced by environmental lead exposure.

OBJECTIVES: To investigate the involvement of oxidative damage in lead-induced toxicity in children aged 3-6 years and to enlighten whether oxidative stress indicators are correlated with the known indices of lead toxicity. METHODS: Blood samples were collected from 408 subjects (217 boys and 191 girls) in the urban kindergartens. The age range of the subjects was 3-6 years. Blood lead levels (BLLs) were analyzed by flameless atomic absorption spectrophotometry. Activities of delta-aminolevulinic acid dehydratase (ALAD), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and contents of glutathione (GSH) in erythrocyte and levels of plasma malondialdehyde (MDA) were analyzed spectrophotometrically in these children. RESULTS: Children with BLLs >or = 100 microg/L had significantly decreased erythrocyte ALAD activities and increased plasma MDA levels compared to the children with BLLs < 100 microg/L. No significant changes were observed in erythrocyte SOD and GSH-Px activities and GSH levels associated with elevated BLLs in these children. CONCLUSION: Present data indicate that oxidative damage could be induced by lead in children with BLLs > or = 100 microg/L, and this may partly be attributed to the inhibited ALAD activities. Statistically significant changes of oxidative stress parameters in preschool children while BLLs were more than 100 microg/L could be implicated that oxidative damage might contribute to lead-induced intellectual impairment.

Child↗
PubMed2006

Outcomes associated with ganciclovir implants in patients with AIDS-related cytomegalovirus retinitis.

PURPOSE: To investigate complications associated with ganciclovir implants used to treat AIDS-related cytomegalovirus (CMV) retinitis, and to identify factors that predict poor outcomes. DESIGN: Retrospective chart review. PARTICIPANTS: Consecutive patients with AIDS-related CMV retinitis from 3 clinical facilities who underwent implantation procedures during the period January 1, 1995 through December 31, 2001. METHODS: Baseline for each patient was the date of the first implantation procedure performed during the study period by one of the facilities' surgeons (index implant). Medical and ophthalmological data were collected at baseline and at specific time points after baseline. The dates on which additional implantation procedures were performed and the dates on which complications or vision loss were identified were also recorded. Relationships between potential risk factors and outcomes were studied by Kaplan-Meier analyses and Cox proportional hazards regression models. MAIN OUTCOME MEASURES: Primary outcome measures included postoperative complications specifically related to or possibly related to ganciclovir implants. A secondary outcome measure was vision loss after implantation procedures. RESULTS: The charts of 174 patients (one study eye per patient; 279 implants) were reviewed. Median follow-up was 14.4 months (range, 0-7 years). Complications specifically related to implants occurred throughout follow-up at a rate of 0.064 events per patient-year. Complications possibly related to implants occurred at an overall rate of 0.377 per patient-year, but seemed to be more common during the first 2 years after baseline. During the first 2 years of follow-up, retinal detachments occurred at a rate of 0.156 events per patient-year. The cumulative risk of vision loss (> or =3 lines of Snellen visual acuity) at 7 years was 70%. Poor outcomes were associated with disease factors (size and activity of lesions), lack of highly active antiretroviral therapy (HAART), and lack of HAART-associated immune reconstitution, but not with surgical factors or implant-specific complications. CONCLUSIONS: Complications specifically associated with ganciclovir implants can occur many years after implantation procedures, but the incidence of such complications is low. Continued vision loss is not attributable directly to complications of implants in most cases. This information will help in planning of treatment strategies for CMV retinitis in long-term survivors of human immunodeficiency virus disease.

AIDS-Related Opportunistic Infections↗
PubMed2006

Standardized visual field assessment for patients with birdshot chorioretinopathy.

PURPOSE: To adapt a standardized technique for assessment of visual fields to the study of patients with birdshot chorioretinopathy and to describe visual field patterns and changes over time for affected individuals. METHODS: A retrospective chart review was performed of patients with a diagnosis of birdshot chorioretinopathy who had undergone at least two automated visual field studies. A masked evaluation of each visual field was performed using standardized criteria. Subjective symptoms and visual acuity measurements were compared to visual field data from the same examination dates. Serial visual field studies were evaluated for changes in the findings over time. RESULTS: Six patients met inclusion criteria. A total of 104 visual field studies (ranging from 2-19 studies per eye) were evaluated. Visual field abnormalities occurred in all tested eyes and were observed even in eyes with a Snellen visual acuity of 20/15. Discordant patterns were observed in the two eyes of some individual patients. On serial testing, multiple patterns of visual field abnormality were observed in the same eye over time. CONCLUSIONS: A standardized protocol for systematic evaluation of visual field measurements can be used to characterize disturbances of vision in patients with birdshot chorioretinopathy. Abnormalities of visual fields may occur even when central visual acuity is preserved.

Chorioretinitis↗
PubMed2006

Coding of glaucoma for patients with uveitis in the medicare database.

PURPOSE: To investigate possible causes for, and implications of, variations in coding of glaucoma for patients with uveitis in the Medicare database. PATIENTS AND METHODS: We identified 6,391 patients coded with one of several ICD-9 codes designating a form of uveitis from a 5% sample of the 1999 Medicare database. The proportion of patients with uveitis codes who also had codes for uveitic glaucoma, primary open-angle glaucoma (POAG), or unspecified open-angle glaucoma (OAG) were determined. The proportion with codes for argon laser trabeculoplasty (ALT), trabeculectomy, visual field examinations, fundus photographs, and gonioscopy were calculated in three groups: patients with both uveitis and uveitic glaucoma; those with both uveitis and POAG; and those with both uveitis and unspecified open-angle glaucoma. Summaries of the total allowed reimbursement related to eye visits and to eye codes were determined. RESULTS: Of the 6,391 patients with uveitis who were studied, 1,260 (19.7%) also had the code for POAG; 412 (6.4%) had the code for OAG; and 117 (1.8%) had the code for uveitic glaucoma. Visual field testing was less common among patients with uveitic glaucoma (37%) than among those with POAG/uveitis (46%) or OAG/uveitis (44%) (P < 0.001). There were no statistically significant differences among the three groups in the amount of total reimbursement related to eye services or eye codes. CONCLUSIONS: The code for POAG appears to be used in lieu of uveitic glaucoma in many cases. Discrepancies are probably not influenced by expected reimbursements, as much as by a lack of understanding about the available ICD-9 codes.

Databases, Factual↗
PubMed2006

Use of gonioscopy in medicare beneficiaries before glaucoma surgery.

PURPOSE: The American Academy of Ophthalmology Preferred Practice Patterns for angle closure and open-angle glaucoma (OAG) patients recommends performing bilateral gonioscopy upon initial presentation to evaluate the possibility of narrow angle or angle-closure glaucoma (ACG) and then repeating the examination at least every 5 years. This study aims to assess how commonly eye care providers perform gonioscopy before planned glaucoma surgery in OAG, anatomic narrow angle, and ACG in the Medicare population. METHODS: Data obtained from a 5% random sample of Medicare beneficiaries undergoing glaucoma surgery in the United States in 1999 were retrospectively reviewed. The proportion of patients with evidence of at least one gonioscopic examination before glaucoma surgery was determined for the period of 1995 to 1999. Demographic and clinical factors potentially influencing the decision to perform gonioscopy were also examined. RESULTS: Overall, gonioscopy is apparently performed in 49% of Medicare beneficiaries during the 4 to 5 years preceding glaucoma surgery. This rate was significantly lower (P < 0.001) in patients with OAG (46%), as compared with anatomic narrow angle (58%) and ACG (57%) patients. Hispanics, elderly (aged 70 to 84), patients undergoing laser iridotomy, and patients receiving care in the New York/New Jersey area all had significantly higher apparent preoperative gonioscopy rates (P < 0.05). CONCLUSIONS: Gonioscopy examination before glaucoma surgery in Medicare beneficiaries is underused, undercoded, and/or miscoded, given current recommendations. Underuse is of particular concern in patients undergoing laser iridotomy as it is the diagnostic test of choice in ACG.

Aged↗
PubMed2006

Treatment of uncorrected refractive error improves vision-specific quality of life.

OBJECTIVES: To evaluate the benefit of eyeglasses and magnifiers in elderly patients with uncorrected refractive errors. DESIGN: A single-center, randomized, prospective, controlled trial (September 2001 to August 2003). SETTING: Los Angeles County, California. PARTICIPANTS: One hundred thirty-one community-dwelling persons aged 65 and older who had habitual distance visual acuity of 20/32 or worse and whose distant visual acuity, near visual acuity, or both could be improved with eyeglasses, a magnifier, or both by two lines of acuity or more. INTERVENTION: Sixty-six were randomized to receive a prescription and voucher for free eyeglasses, a magnifier, or both immediately, and 65 were randomized to receive a prescription and voucher after the 3-month follow-up visit (the control group). MEASUREMENTS: Primary outcome was vision-specific functioning as measured using the 25-item National Eye Institute-Visual Functioning Questionnaire (NEI-VFQ). Secondary outcomes were distance and near visual acuity and overall functioning as measured using the Rosow-Breslau function questionnaire. RESULTS: In the intention-to-treat analysis of 3-month follow-up data, participants who received the eyeglasses prescription and voucher immediately had greater improvement in NEI-VFQ composite scores than the control group (P<.01). They also had greater improvement in perceptions of their general vision (P<.01), distance visual acuity (P=.03), near visual acuity (P=.04), and mental health (P=.02). CONCLUSION: Correction of uncorrected refractive error, one of the leading causes of visual impairment in older people, improved the vision-specific quality of life of community-dwelling older persons.

Aged↗
PubMed2006

Hemorheologic abnormalities associated with HIV infection: altered erythrocyte aggregation and deformability.

PURPOSE: To investigate possible alterations of erythrocyte aggregation and deformability, which are factors that can influence blood flow, in human immunodeficiency virus (HIV)-infected individuals and to determine whether these factors are related to the severity of immunodeficiency. METHODS: Laboratory evaluations were performed on 46 HIV-infected individuals and 44 HIV-negative control subjects. Current and nadir (lowest previous) CD4+ T-lymphocyte counts were identified for each subject. Erythrocyte aggregation was measured using a fully automatic erythrocyte aggregometer. Factors related to erythrocyte aggregation were also determined: erythrocyte sedimentation rate (ESR), zeta sedimentation ratio (ZSR), and plasma fibrinogen levels. Erythrocyte deformability was observed at various fluid shear stress levels, with a laser diffraction ektacytometer. Correlations were sought between each of these measures and current or nadir CD4+ T-lymphocyte counts, and each measure was compared between three subgroups based on current and nadir CD4+ T-lymphocyte counts (severely immunosuppressed, immune reconstituted, never severely immunosuppressed). RESULTS: The following parameters were significantly different between HIV-infected subjects and controls: increased erythrocyte aggregation, at stasis (P < 0.001) and low shear stress (P < 0.001), increased ESR (P < 0.001), increased ZSR (P < 0.028), increased serum fibrinogen (P = 0.015), and decreased erythrocyte deformability (P < 0.001). Only erythrocyte aggregation at stasis correlated significantly with current CD4+ T-lymphocyte count (r = - 0.344, P = 0.022). None of the parameters was significantly different between HIV-infected subgroups. CONCLUSIONS: Increased aggregation and decreased deformability of erythrocytes are associated with HIV-infection regardless of the severity of immunodeficiency. HIV-infected individuals may be at risk for progressive retinal microvascular damage from persistent hemorheologic abnormalities, despite immune reconstitution associated with potent antiretroviral drug therapies.

Adult↗
PubMed2006

Reaction kinetics of stover liquefaction in recycled stover polyol.

The purpose of this research was to study the kinetics of liquefaction of crop residues. The liquefaction of corn stover in the presence of ethylene glycol and ethylene carbonate using sulfuric acid as a catalyst was studied. It was found that the liquefaction yield was a function of ratio of solvent to corn stover, temperature, residence time, and amount of catalyst. Liquefaction of corn stover was conducted over a range of conditions encompassing residence times of 0-2.5 h, temperatures of 150-170 degrees C, sulfuric acid concentrations of 2-4% (w/w), and liquefaction reagent/corn stover ratio of 1-3. The liquefaction rate constants for individual sets of conditions were examined using a first-order reaction model. Rate constant increased with the increasing of liquefaction temperature, catalyst content, and liquefaction reagent/corn stover ratio. Reuse of liquefied biomass as liquefying agent was also evaluated. When using recycled liquefied biomass instead of fresh liquefaction reagent, the conversion is reduced. It appeared that 82% of liquefaction yield was achieved after two times of reuse.

Complex Mixtures↗
PubMed2006

Liquefaction of corn stover and preparation of polyester from the liquefied polyol.

This research investigated a novel process to prepare polyester from corn stover through liquefaction and crosslinking processes. First, corn stover was liquefied in organic solvents (90 wt% ethylene glycol and 10 wt% ethylene carbonate) with catalysts at moderate temperature under atmospheric pressure. The effect of liquefaction temperature, biomass content, and type of catalyst, such as H2SO4, HCl, H3PO4, and ZnCl2, was evaluated. Higher liquefaction yield was achieved in 2 wt% sulfuric acid, 1/4 (w/w) stover to liquefying reagent ratio; 160 degrees C temperature, in 2 h. The liquefied corn stover was rich in polyols, which can be directly used as feedstock for making polymers without further separation or purification. Second, polyester was made from the liquefied corn stover by crosslinking with multifunctional carboxylic acids and/or cyclic acid anhydrides. The tensile strength of polyester is about 5 MPa and the elongation is around 35%. The polyester is stable in cold water and organic solvents and readily biodegradable as indicated by 82% weight loss when buried in damp soil for 10 mo. The results indicate that this novel polyester could be used for the biodegradable garden mulch film production.

Complex Mixtures↗
PubMed2006

Cloning and expression analysis of SKn-type dehydrin gene from bean in response to heavy metals.

A heavy metal responsive gene PvSR3 (GenBank accession number U54703) encoding an acid dehydrin was isolated from a mercuric chloride-treated bean (Phaseolus vulgaris L.) leaf cDNA library by differential screening using cDNAs derived from treated and untreated plants. The PvSR3 cDNA is 981-bp long and has a 606-bp open-reading frame with a 202-residue-deduced amino acid sequence. The PvSR3 sequence contains two conserved repeats of the characteristic lysine-rich K segment (EKKGIMDKIKEKLPG) preceded by an 8-serine residue stretch, whereas the Y segment (DEYGNP) conserved motif is absent. The deduced protein has a calculated molecular weight of 23 kDa and an isoelectric point of 5.2. Sequence similarity and comparative analysis showed that PvSR3 shares 70 and 73% similarity with the dehydrin of poplar and pepper, respectively. Southern hybridizations indicated that PvSR3 was a low copy-number gene. Northern blot analysis revealed that PvSR3 mRNA was weakly detected in seedling leaves. However, the gene expression was strongly stimulated by heavy metals, such as mercury, cadmium, arsenic, and copper, whereas virus infection and salt had little effect on it. In contrast, PvSR3 was not responsive to drought or abscisic acid (ABA), and was downregulated by UV radiation. Furthermore, PvSR3 was upregulated by the exogenous signaling molecules, including salicylic acid (SA) and hydrogen peroxide (H2O2). It is suggested that PvSR3 is extremely related to heavy metal stress, and might play an important role in metal detoxification and resistance to the damage caused by heavy metals.

Abscisic Acid↗
PubMed2006

Impaired expression of cardiac adiponectin in leptin-deficient mice with viral myocarditis.

A mouse model of encephalomyocarditis (EMC) virus-induced myocarditis was used to investigate the expression of adiponectin in damaged cardiomyocytes. We intraperitoneally injected EMC virus into leptin-deficient ob/ob (OB) mice and wild-type (WT) mice. OB mice were divided into two subgroups consisting of mice with no intervention and mice receiving leptin replacement starting simultaneously with viral inoculation. We determined differences in heart weight, cardiac histological score, numbers of infiltrating and apoptotic cells in the myocardium, expression levels of adiponectin and TNF-alpha mRNA in the heart, adiponectin immunoreactivity in myocytes, adiponectin and TNF-alpha concentrations in the heart, and immunoreactivity of adiponectin receptors in myocytes between OB mice and WT mice. There was significantly decreased adiponectin mRNA expression, immunoreactivity, and protein level in the heart, and reduced immunoreactivity of adiponectin receptor 1 in myocytes from OB mice on days 4 and 8 after viral inoculation as compared with those in WT mice, together with increased cardiac weight, severe inflammatory myocardial damage, and increased levels of cardiac TNF-alpha mRNA and protein. Replacement of leptin in OB mice inhibited the development of severe myocarditis through augmentation of adiponectin mRNA, immunoreactivity, and protein level, increased adiponectin receptor 1 immunoreactivity in myocytes, and suppressed levels of TNF-alpha mRNA and protein. These results suggest that impaired expression of cardiac adiponectin may contribute to the progression of viral myocarditis through enhanced expression of TNF-alpha under a leptin-deficient condition.

Adiponectin↗
PubMed2006

[Expression pattern and level of cytotoxic T lymphocyte-associated antigen-4 targeted anti-caries plasmids in eukaryotic cells].

OBJECTIVE: To investigate and compare the expression pattern and level of targeted anti-caries plasmids encoding different-size antigens in eukaryotic cells. METHODS: The A-P fragment of PAc (surface protein antigen) was removed from pGJA-P encoding the signal peptide, extracellular domains of human CTLA-4, human Ig hinge, CH2 and CH3 domains, A-P fragment of PAc and GLU (glucan binding domain) region of GTF-I of Streptococcus mutans, to obtain the plasmid pGJGLU. pCI vector skeleton of pGJA-P or pGJGLU was replaced by pVAX1 to construct plasmids pGJA-P/VAX and pGJGLU/VAX. CTLA4-Ig-GLU fragment was removed from pGJGLU and inserted into the vector pEGFP-N1 to obtain the recombinant plasmid pGJGLU/GFP. The CHO cells were transfected with those plasmids by using liposome and the expression of fusion protein was observed with fluorescence microscope. ELISA was used to detect the expression level of fusion proteins in cultured supernatants. RESULTS: Specific vesicles with green fluorescence could be observed in the CHO cells transfected with pGJGLU/GFP. The recombinant fusion protein could be detected in the cultured supernatants of CHO cells transfected with pGJA-P/VAX, pGJGLU/VAX and pGJGLU/GFP, of which the concentration was different. The highest concentration of recombinant fusion protein was observed in the supernatants of CHO cells transfected with pGJGLU/VAX. CONCLUSIONS: CTLA-4 targeted fusion protein could be expressed and secreted by eukaryotic cells. The size of antigen may affect the expression level of CTLA-4 targeted anti-caries DNA vaccine.

Animals↗
PubMed2006

Bone mineral density-affecting genes in Africans.

BACKGROUND: We have recently reported the role of environmental exposure in the ethnic diversity of bone mineral density (BMD). Potential genetic difference has not been adequately assessed. PURPOSE: To determine allele frequencies of BMD-affecting genes and their association with BMD in Africans. METHODS: Allele frequencies at 18 polymorphic sites in 13 genes that affect BMD in Asians and/or Caucasians were determined in 143 recent immigrants (55 men and 88 women, 18-51 years of age) from sub-Saharan Sudan to the United States. Genetic association studies were performed. RESULTS: Among the 14 single-nucleotide polymorphisms (SNPs), 10 were significantly different in allele frequency between Sudanese and Asians, and 10 between Sudanese and Caucasians. Only the osteocalcin gene was not significantly different in allele frequency among Sudanese, Asians and Caucasians. Allele frequencies in the TGFB, COL1A1 and CSR genes were extremely low (<0.04) in the Sudanese. Frequencies of microsatellite alleles in four genes were significantly different among Sudanese, Asians and Caucasians. SNPs in the VDR and ERalpha genes were associated with BMD and/or BMC (bone mineral content) at several bone sites. CONCLUSIONS: Genetic difference may play a role in the ethnic diversity in BMD and/or BMC.

Adolescent↗
PubMed2005

Analysis of the expressed heavy chain variable-region genes of Macaca fascicularis and isolation of monoclonal antibodies specific for the Ebola virus' soluble glycoprotein.

The cynomolgus macaque, Macaca fascicularis, is frequently used in immunological and other biomedical research as a model for man; understanding it's antibody repertoire is, therefore, of fundamental interest. The expressed variable-region gene repertoire of a single M. fascicularis, which was immune to the Ebola virus, was studied. Using 5' rapid amplification of cDNA ends with immunoglobulin (Ig)G-specific primers, we obtained 30 clones encoding full-length variable, diversity, and joining domains. Similar to the human V(H) repertoire, the M. fascicularis repertoire utilized numerous immunoglobulin heavy variable (IGHV) gene fragments, with the V(H)3 (41%), V(H)4 (39%), and V(H)1 (14%) subgroups used more frequently than the V(H)5 (3.9%) or V(H)7 (1.7%) subgroups. Diverse immunoglobulin heavy joining (IGHJ) fragments also appeared to be utilized, including a putative homolog of JH5beta gene segment identified in the related species Macaca mulatta, Rhesus macaque, but not in humans. Although the diverse V region genes in the IgG antibody repertoire of M. fascicularis had likely undergone somatic hypermutations (SHMs), they nevertheless showed high nucleotide identity with the corresponding human germline genes, 80-89% for IGHV and 72-92% for IGHJ. M. fascicularis and human V(H) genes were also similar in other aspects: length of complementarity-determining regions and framework regions, and distribution of consensus sites for SHMs. Finally, we demonstrated that monoclonal antibodies (mAbs) specific for an Ebola protein could be obtained from M. fascicularis tissue samples by phage display technology. In summary, the study provides new insight into the M. fascicularis V region gene repertoire and further supports the idea that macaque-derived mAbs may be of therapeutic value to humans.

Amino Acid Sequence↗
PubMed2005

Satisfaction as a predictor of clinical outcomes among chiropractic and medical patients enrolled in the UCLA low back pain study.

STUDY DESIGN: Observational study conducted within a randomized clinical trial. OBJECTIVES: The objective of this study is to estimate the effects of patient satisfaction on subsequent changes in pain and disability among low back pain patients randomized to chiropractic or medical care in a managed-care practice setting. SUMMARY OF BACKGROUND DATA: Recent studies of low back pain treatments have shown chiropractic patients to be more satisfied with their care than medical patients. However, little is known about the relation between patient satisfaction and clinical outcomes. METHODS: A total of 681 low back pain patients presenting to three southern California healthcare clinics and screened for serious spinal pathology and contraindications were randomized to medical care with and without physical therapy, and chiropractic care with and without physical modalities, and followed for 18 months. Satisfaction with back care was measured on a 40-point scale and observed at 4 weeks following randomization. The primary outcome variables, observed between 6 weeks and 18 months of follow-up, are average and most severe low back pain intensity in the past week, assessed with 0 to 10 numerical rating scales, low back-related disability, assessed with the 24-item Roland-Morris Disability Questionnaire, and remission from clinically meaningful pain and disability. Perceived change in low back symptoms was a secondary outcome. RESULTS: Greater satisfaction increased the odds of remission from clinically meaningful pain and disability at 6 weeks (adjusted odds ratio [OR] for 10-point increase in satisfaction = 1.61, 95% confidence interval [CI] = 0.99, 2.68), but not at 6, 12, or 18 months (6 months: adjusted OR = 1.05, 95% CI = 0.73, 1.52; 12 months: adjusted OR = 0.94, 95% CI = 0.67, 1.32; 18 months: adjusted OR = 1.07; 95% CI = 0.76, 1.50). Perception of improvement was greater among highly satisfied than less satisfied patients throughout the 18-month follow-up period. The estimated effects of satisfaction on clinical outcomes were similar for medical and chiropractic patients. CONCLUSIONS: Patient satisfaction may confer small short-term clinical benefits for low back pain patients. Long-term perceived improvement may reflect, in part, perceived past improvement as measured by satisfaction.

Adult↗
PubMed2005

Functional redundancy of AtFtsH metalloproteases in thylakoid membrane complexes.

FtsH is an ATP-dependent metalloprotease found in bacteria, mitochondria, and plastids. Arabidopsis (Arabidopsis thaliana) contains 12 AtFtsH proteins, three in the mitochondrion and nine in the chloroplast. Four of the chloroplast FtsH proteins are encoded by paired members of closely related genes (AtFtsH1 and 5, and AtFtsH2 and 8). We have previously reported that AtFtsH2 and 8 are interchangeable components of AtFtsH complexes in the thylakoid membrane. In this article, we show that the var1 variegation mutant, which is defective in AtFtsH5, has a coordinate reduction in the AtFtsH2 and 8 pair, and that the levels of both pairs are restored to normal in var1 plants that overexpress AtFtsH1. Overexpression of AtFtsH1, but not AtFtsH2/VAR2, normalizes the pattern of var1 variegation, restoring a nonvariegated phenotype. We conclude that AtFtsH proteins within a pair, but not between pairs, are interchangeable and functionally redundant, at least in part. We further propose that the abundance of each pair is matched with that of the other pair, with excess subunits being turned over. The variegation phenotype of var1 (as well as var2, which is defective in AtFtsH2) suggests that a threshold concentration of subunits is required for normal chloroplast function. AtFtsH1, 2, 5, and 8 do not show evidence of tissue or developmental specific expression. Phylogenetic analyses revealed that rice (Oryza sativa) and Arabidopsis share a conserved core of seven FtsH subunit genes, including the AtFtsH1 and 5 and AtFtsH2 and 8 pairs, and that the structure of the present-day gene families can be explained by duplication events in each species following the monocot/dicot divergence.

Arabidopsis↗
PubMed2005

Visual field testing in glaucoma Medicare beneficiaries before surgery.

OBJECTIVE: The standard of care for progressive glaucoma that requires medical or surgical intervention includes visual field (VF) testing at least annually. This study aims to assess how commonly ophthalmologists perform VF testing before planned glaucoma surgery in the Medicare population, and whether variations in conformance occur across demographic and clinical subgroups. DESIGN: Retrospective, observational, population-based analysis. PARTICIPANTS: Thirteen thousand seven hundred fifty-three Medicare beneficiaries. METHODS: Data were obtained from a 5% random sample of Medicare beneficiaries undergoing glaucoma surgery in the United States from 1995 to 1999. The proportion of patients with evidence of at least 1 VF examination in the year before glaucoma surgery was determined. MAIN OUTCOME MEASURE: Rate of VF testing in the year before glaucoma surgery. RESULTS: Overall, 70% of patients had at least 1 VF test in the year preceding glaucoma surgery. This rate was significantly lower (P<0.001) in patients > or =85 years (56%), blacks (64%), patients with race other than white or black (66%), patients with diabetic retinopathy (60%), and patients with bilateral blindness (47%). CONCLUSIONS: The use of VF testing before surgery in glaucoma Medicare beneficiaries is suboptimal relative to the recommended standard of care. Underutilization is of particular concern in blacks, who are at increased risk of glaucomatous damage. Quality-of-care initiatives are needed to facilitate appropriate preoperative evaluations of glaucoma Medicare beneficiaries for glaucoma surgery.

Aged↗