Biomedical subjects

James A Kennedy

Publications and source records attributed to James A Kennedy.

11 recordsLinked to original sources

PubMed2006

Effect of shading on accumulation of flavonoid compounds in (Vitis vinifera L.) pinot noir fruit and extraction in a model system.

Accumulation and compositional changes of flavonols, proanthocyanidins, and anthocyanins were measured in Vitis vinifera L. cv. Pinot noir in shaded and exposed treatments. In addition, extraction of these compounds into a model wine solution was measured. The study was conducted in a commercial vineyard within a uniform zone of relatively low vigor vines. Light exclusion boxes were installed on pairs of clusters on the same shoot (shaded treatment), and a second set of clusters on an adjacent shoot were labeled as the exposed treatment. Fruit samples were harvested at the onset of ripening (véraison) and at commercial harvest. Cluster shading resulted in a substantial decrease in mg/berry accumulation of flavonols and skin proanthocyanidins and minimal differences in anthocyanins. In analyzing seed proanthocyanidins by phloroglucinolysis, shaded and exposed treatments were similar at véraison; however, by harvest, the shaded treatment had higher extension and terminal subunits (nmol/seed) as compared to the exposed treatment. For skin proanthocyanidins, shaded fruit was lower for all subunits (nmol/berry) at both véraison and harvest. Shading caused an increase in the proportion of (-)-epicatechin and a decrease in (-)-epigallocatechin at harvest in skin extension subunits. Seed proanthocyanidins in shaded fruit contained a lower proportion of (+)-catechin and a higher proportion of (-)-epicatechin-3-O-gallate in extension subunits and a lower proportion of (+)-catechin and (-)-epicatechin-3-O-gallate and a higher proportion of (-)-epicatechin in terminal subunits. For anthocyanins, the shaded treatment had a proportional reduction in delphinidin, cyanidin, petunidin, and malvidin and a large increase in peonidin glucosides. The model extractions from the two treatments paralleled differences in the fruit with a lower concentration of flavonols, anthocyanins, and proanthocyanidins in the shaded treatment. The skin proanthocyanidin percent extraction was found to be approximately 17% higher in the exposed model extraction than the shaded treatment.

Flavonoids↗

PubMed2006

Diagnostic efficacy of a reverse transcriptase-polymerase chain reaction assay to screen cattle for persistent bovine viral diarrhea virus infection.

OBJECTIVE: To evaluate diagnostic efficacy of a reverse transcriptase-PCR assay performed on pooled supernatant from fresh tissue samples to screen cattle for persistent infection with bovine viral diarrhea virus (BVDV). DESIGN: Cross-sectional study. SAMPLE POPULATION: 174 pooled supernatant samples representing 12,528 animals between 1 and 12 months old. PROCEDURES: The supernatant was collected from fresh tissue samples suspended in phosphate-buffered saline solution that had been submitted for testing for BVDV infection. Supernatant samples were pooled, with pool size limited to < or = 100 samples, and assayed with a reverse transcriptase-PCR assay for BVDV. Results of the PCR assay were compared with results of an antigen-capture ELISA performed on individual tissue samples. RESULTS: Results of the PCR assay were positive for 27 of the 174 pooled samples (mean pool size, 72 samples). For 23 of these 27 pooled samples, results of the ELISA were positive for 1 or more of the individual tissue samples represented in the pooled sample, whereas for 4 of these pooled samples, results of the ELISA were negative for all individual tissue samples represented in the pooled sample. Results of the ELISA were negative for all individual tissue samples represented in the 147 pooled samples with negative PCR assay results. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the reverse transcriptase-PCR assay can be used to screen cattle for persistent BVDV infection, with calculated sensitivity of 100% (95% confidence interval, 85.2% to 100%) and calculated specificity of 97.5% (95% confidence interval, 93.4% to 99.3%).

Animals↗

PubMed2006

Reverse transcription-polymerase chain reaction on pooled samples to detect bovine viral diarrhea virus by using fresh ear-notch-sample supernatants.

Ear-notch samples from 3,599 yearling heifers were collected to detect persistently infected (PI) animals with suspect bovine viral diarrhea virus (BVDV). Individual immunohistochemistry (IHC), individual antigen-capture enzyme-linked immmunosorbent assay (AC-ELISA), and reverse transcription-polymerase chain reaction (RT-PCR) tests with pooled ear-notch supernatants were compared with samples from 3,016 heifers, whereas RT-PCR ear-notch pools and individual AC-ELISA tests were compared with samples from all 3,599 heifers. Four heifers were identified positive by both IHC and AC-ELISA, whereas the remaining heifers were identified negative by both tests. When supernatant from ear notches from 100 animals was randomly pooled and RT-PCR was accomplished on each pool, RT-PCR identified 2 pools that contained 1 positive AC-ELISA sample and 1 pool that contained 2 positive AC-ELISA samples. Further evaluation of the pooled RT-PCR ear-notch supernatant detected 100% (n = 36) samples spiked with supernatant from a single randomly selected positive AC-ELISA ear notch. Although follow-up confirmatory tests were not completed, all 3 methods correlated 100% in detecting suspect PI animals, with a kappa value of 1. The use of RT-PCR on pooled ear-notch supernatant could provide an initial, rapid, cost-effective method of screening cattle herds for BVDV PI animals. Subsequent serial testing with an AC-ELISA to evaluate individual samples included in the positive pool could minimize the length of time other animals are exposed to the virus.

Animals↗

PubMed2005

Influence of vine vigor on grape (Vitis vinifera L. Cv. Pinot Noir) and wine proanthocyanidins.

The relationships between variations in grapevine (Vitis vinifera L. cv. Pinot noir) growth and resulting fruit and wine phenolic composition were investigated. The study was conducted in a commercial vineyard consisting of the same clone, rootstock, age, and vineyard management practices. The experimental design involved monitoring soil, vine growth, yield components, and fruit composition (soluble solids, flavan-3-ol monomers, proanthocyanidins, and pigmented polymers) on a georeferenced grid pattern to assess patterns in growth and development. Vine vigor parameters (trunk cross-sectional area, average shoot length, and leaf chlorophyll) were used to delineate zones within both blocks to produce research wines to investigate the vine-fruit-wine continuum. There was no significant influence of vine vigor on the amount of proanthocyanidin per seed and only minimal differences in seed proanthocyanidin composition. However, significant increases were found in skin proanthocyanidin (mg/berry), proportion of (-)-epigallocatechin, average molecular mass of proanthocyanidins, and pigmented polymer content in fruit from zones with a reduction in vine vigor. In the wines produced from low-vigor zones, there was a large increase in the proportion of skin tannin extracted into the wine, whereas little change occurred in seed proanthocyanidin extraction. The level of pigmented polymers and proanthocyanidin molecular mass were higher in wines made from low-vigor fruit compared to wines made from high-vigor fruit, whereas the flavan-3-ol monomer concentration was lower.

Chlorophyll↗

PubMed2004

Analysis of the oxidative degradation of proanthocyanidins under basic conditions.

Proanthocyanidin isolates from grape (Vitis vinifera L. cv. Pinot noir) skin and seed underwent oxidative degradation in solution (10 g/L) under basic conditions while exposed to atmospheric oxygen. Degradation was monitored by reversed-phase HPLC following acid-catalyzed cleavage in the presence of excess phloroglucinol (phloroglucinolysis) and by high-performance gel permeation chromatography. All isolates degraded under these conditions and followed second-order kinetics for over 1 half-life, consistent with an oxidation reaction. The conversion of proanthocyanidins to known subunits (conversion yield) when measured by phloroglucinolysis showed a dramatic decline over the course of the reaction. With the exception of (+)-catechin extension subunits, all individual subunits decreased in concentration during the oxidation process, also following second-order kinetics for over 1 half-life. Skin proanthocyanidins degraded the fastest due to the presence of (-)-epigallocatechin extension subunits. Seed procyanidins were degraded with and without flavan-3-ol monomers. Flavan-3-ol monomers slowed the rate of seed procyanidin degradation. The mean degree of polymerization (mDP) determined by phloroglucinolysis indicated a large decrease in mDP as the reaction progressed; yet, by GPC, the size distribution of all proanthocyanidins changed little in comparison. The conversion yield could be an important parameter to follow when using phloroglucinolysis as a means for determining proanthocyanidin mDP, and when monitoring the oxidative degradation of proanthocyanidins.

Chromatography, High Pressure Liquid↗

PubMed2003

Direct method for determining seed and skin proanthocyanidin extraction into red wine.

A method was developed for determining the amount of seed and skin proanthocyanidin extraction into wines by direct measurement. This method was based upon the analysis of proanthocyanidin cleavage products after acid catalysis in the presence of excess phloroglucinol. On the basis of the analysis of proanthocyanidin extracts from grape tissues, two observations were made as follows: (i) the seed and skin proanthocyanidin extension subunit compositions were considerably different from each other, and (ii) their composition did not vary with extraction time. Thus, by comparing the proportional extension subunit composition of proanthocyanidins in wine relative to their proportional composition in corresponding grape seed and skin, it was possible to determine the contribution of each to wine. To provide additional information, the procedure was used to investigate seed and skin proanthocyanidin extraction during commercial-scale fermentations that had undergone 4 or 10 day low temperature prefermentation skin contact prior to the onset of fermentation. The results for both fermentations indicated that the proportion of skin tannin declined during fermentation and also showed that at the end of fermentation the amount and proportion of skin tannin were the same.

Anthocyanins↗

PubMed2003

Hop (Humulus lupulus L.) proanthocyanidins characterized by mass spectrometry, acid catalysis, and gel permeation chromatography.

Proanthocyanidins extracted from hops (Humulus lupulus L. cv. Willamette) were subjected to Sephadex LH-20 column chromatography using a step gradient of methanol, water, and acetone. The resulting fractions were analyzed by acid catalysis, electrospray ionization and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and gel permeation chromatography (GPC). The proanthocyanidins contained catechin and epicatechin as monomers and as terminal and extension units. Epigallocatechin was found as extension units. The mean degree of polymerization (mDP) of the crude proanthocyanidins was 7.8, but heptamers were the largest oligomers visible in mass spectra of the whole. In the last-eluted fraction (mDP = 22.2), polymers as large as 20-mers were detected by MALDI-TOF-MS, demonstrating the effectiveness of prior separation in improving MS detection. GPC data correlated well with acid catalysis results, confirming the presence of large polymers that were not detected by MS.

Anthocyanins↗

PubMed2003

Analysis of proanthocyanidins by high-performance gel permeation chromatography.

A high-performance gel permeation chromatography method was developed for the analysis of proanthocyanidins. The isocratic method consisted of two porous polystyrene-divinylbenzene columns (300 x 7.5 mm each, 5 microm, 100 and 500 A individual pore size) and a mobile phase consisting of N,N-dimethylformamide containing 1% (v/v) acetic acid, 5% (v/v) water and 0.15 M lithium chloride. The flow-rate was maintained at 1 ml/min, with a column temperature of 60 degrees C and with detection at 280 nm. The method was used to analyze proanthocyanidin fractions of increasing molecular mass and from different plant tissues. The average molecular mass of proanthocyanidin fractions as determined by acid catalysis in the presence of phloroglucinol, related well with their gel permeation chromatography column retention, yet significant differences in the retention properties between individual plant tissue isolates existed. Proanthocyanidin compositional differences between isolates may explain these differences. A second-order calibration curve was generated from fractionated grape seed proanthocyanidins and this curve was used to analyze grape seed proanthocyanidins isolated from grapes harvested at extremes of maturity.

Chromatography, Gel↗

PubMed2003

Axis V revisited.

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Activities of Daily Living↗

PubMed2003

Field validation and assessment of an enzyme-linked immunosorbent assay for detecting chronic wasting disease in mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni).

Tissue samples (n = 25,050 total) from 23,256 mule deer (Odocoileus hemionus), Rocky Mountain elk (Cervus elaphus nelsoni), and white-tailed deer (Odocoileus virginianus) collected statewide in Colorado were examined for chronic wasting disease (CWD) using an enzyme-linked immunosorbent assay developed by Bio-Rad Laboratories, Inc. (brELISA), in a 2-phase study. In the validation phase of this study, a total of 4,175 retropharyngeal lymph nodes (RLN) or obex (OB) tissue samples were examined independently by brELISA and immunohistochemistry (IHC). There were 137 IHC-positive samples and 4,038 IHC-negative samples. Optical density (OD) values from brELISA were classified as "not detected" or "suspect" based on recommended cutoff values during the validation phase. Using IHC-positive cases as known CWD-infected individuals and assuming IHC-negative cases as uninfected, the relative sensitivity of brELISA depending on species ranged from 98.3% to 100% for RLN samples and 92.1% to 93.3% for OB samples; the relative specificity of brELISA depending on species ranged from 99.9% to 100% for RLN samples and was 100% for OB samples. Overall agreement between brELISA and IHC was > or = 97.6% in RLN samples and > or = 95.7% in OB samples of all species where values could be calculated; moreover, mean brELISA OD values were > or = 46X higher in IHC-positive samples than in IHC-negative samples. Discrepancies were observed only in early-stage cases of CWD. Based on the validation phase data, only RLN samples were collected for the field application phase of this study and only samples with brELISA OD values > 0.1 were examined by IHC. Among 20,875 RLN samples screened with brELISA during this second testing phase, 155 of 8,877 mule deer, 33 of 11,731 elk, and 9 of 267 white-tailed deer samples (197 total) had OD values > 0.1 and were further evaluated by IHC to confirm evidence of CWD infection. Of cases flagged for IHC follow-up, 143 of 155 mule deer, 29 of 33 elk, and all 9 white-tailed deer were confirmed positive. Mean (+/- SE) OD values for IHC-positive cases detected during the field application phase were comparable with those measured in RLN tissues during the validation phase. Based on these data, brELISA was determined to be an excellent rapid test for screening large numbers of samples in surveys designed to detect CWD infections in deer and elk populations.

Animal Diseases↗

PubMed2002

Maintenance of low-density lipoprotein goal with step-down pravastatin therapy.

STUDY OBJECTIVE: To determine whether patients who had achieved their National Cholesterol Education Program (NCEP)-derived goals for low-density lipoprotein (LDL) cholesterol with pravastatin would benefit from step-down therapy. DESIGN: Prospective, randomized, open-label study SETTING: Kansas City Veterans Affairs Medical Center. PATIENTS: One hundred four men who were taking pravastatin once/day and had maintained their NCEP-defined LDL goal for at least 3 months. INTERVENTION: Fifty-three patients were randomized to group 1, for which the dosing frequency was changed from daily to every other day, and 51 patients were randomized to group 2, for which the daily dose was halved. MEASUREMENTS AND MAIN RESULTS: Fasting lipid profiles and hepatic transaminase levels were analyzed at baseline, 2 months, and 4 months. Lifestyle, concomitant drug therapy, adverse events, weight, and compliance were noted at baseline and month 4. Thirty-one patients (58%) from group 1 and 22 patients (43%) from group 2 did not remain at their LDL goal after step-down pravastatin therapy Mean LDL at study end was 113 mg/dl for group 1 and 104 mg/dl for group 2 (p=0.04). CONCLUSION: More than half (51%) of the patients enrolled did not remain at their LDL goal with step-down pravastatin therapy Therefore, we do not recommend a step-down approach for patients who have achieved their LDL goals. If a clinician decides, however, to attempt dosage reduction, the preferred regimen appears to be to halve the current dose once/day (vs administering the current dose every other day). A fasting lipid profile should be evaluated at 2 months and 4 months after step-down therapy begins to ensure that desired outcomes are achieved.

Aged↗