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Biomedical subjects

G W Rogers

Publications and source records attributed to G W Rogers.

14 recordsLinked to original sources
PubMed1992

Decreased hepatic uptake of cholesterol and retinol in the dimethylnitrosamine rat model of cirrhosis.

The fenestrated endothelium of the liver sinusoids forms a sieve between the circulation and hepatocytes. Fenestrae selectively permit the entrance of relatively small chylomicron remnants into the space of Disse to contact hepatocyte receptors, but obstruct the passage of the larger parent chylomicrons. Much of dietary cholesterol and most of retinol are transported as esters in the core of chylomicrons. In the dimethyl nitrosamine rat model of cirrhosis, we have described a rapid reduction in size and number of fenestrae well before the onset of cirrhosis. Concurrent with this decreased porosity is a decreased trapping of radio-labelled dietary cholesterol and retinol by these livers. We postulate that the less porous "liver sieve" hinders the hepatic uptake of chylomicron remnants, with consequent disturbance of cholesterol and retinol metabolism.

Animals↗
PubMed1992

The effect of milking machine liner slip on new intramammary infections.

New IMI of cows milked with high and low slip rate milking machine liners were compared. High slip liners used in this study averaged 6.1 initial slips and 7.6 major vacuum fluctuations per cow milking, and low slip liners averaged 3.6 initial slips and 3.1 major vacuum fluctuations per cow milking. Least squares means for new IMI rates per 100 cow days were .49 in the high slip group and .27 in the low slip group. Rates of clinical cases per 100 cow days were .35 in the high slip group and .20 in the low slip group. New IMI rates for cows entering the trial with an existing infection were .81 in the high slip group and .39 in the low slip group. More new IMI tended to occur with cows milked with the high slip liners than with low slip liners.

Animals↗
PubMed1992

Predicting body weight and wither height in Holstein heifers using body measurements.

Relationships between body weight, wither height, and various other body traits, including heart girth, body length, and hip width, were studied using data from six experiments with 2625 observations. Body weight and wither height were regressed on the other body traits. Regressions of body weight including the linear, quadratic, and cubic effects of a single independent variable (heart girth, wither height, hip width or body length) indicated that each measurement would be useful in predicting body weight (R2 > .95); the regression of body weight on heart girth had the highest R2, followed by hip width. Similarly, regressions of wither height on heart girth, wither height, hip width, or body length, including linear, quadratic, and cubic effects, yielded R2 > .99. Regressions considering multiple traits as independent variables showed that the addition of a second body trait added little to the already high multiple correlations found with a single variable. In management situations for which body weight or wither height cannot be measured, various other traits can be used to estimate these body measurements accurately.

Animals↗
PubMed1991

Correlations among linear type traits and somatic cell counts.

Genetic and phenotypic correlations between linear type traits and SCC were estimated from lactation average SCC from Pennsylvania DHIA and Holstein linear type evaluations from Sire Power, Inc. and Holstein Association using REML. Correlations were estimated between linear type traits and SCC measured in first lactation and between linear type traits measured in first lactation and SCC measured in second or third lactation. Data sets ranged in size from 4294 daughters of 216 sires to 58,235 daughters of 301 sires. Phenotypic and genetic correlations between the linear traits that reflect body and locomotive characteristics and SCC were generally small and unimportant. Phenotypic correlations between udder traits and SCC were variable, but cows with higher udder depth scores (higher udders) had lower SCC. Genetic correlations between udder traits and SCC were also variable. Genetic correlations between SCC and udder depth, SCC and fore udder attachment, and SCC and teat placement were negative (favorable). Genetic correlations between teat length and SCC tended to be positive. Genetic correlations were largest in magnitude between udder depth and SCC and ranged from -.21 to -.64 (weighted mean = -.35). Selection for higher udders and closer teat placement will likely improve resistance to mastitis in dairy cattle.

Animals↗
PubMed1991

Relationship among udder and teat morphology and milking characteristics.

Teat cup liner slips, manual milking machine adjustments, milk yields, and milking times were recorded during both morning and evening milkings for 8 d on 97 Holstein cows in The Pennsylvania State University dairy herd. Fore and rear udder heights (distance from floor to udder), udder levelness, distances between teats (before and after milking), teat lengths, teat diameters, and teat end shapes were measured on the same cows. Product-moment correlations among the morphological characteristics, linear slips, manual adjustments, milk yields, and milking times were determined. Residual correlations from a model including lactation number and DIM (linear and quadratic) were also calculated. The variation among cows in machine liner slips and manual adjustments within and across lactation number and DIM can be partially explained by udder and teat morphology. Wider teats were associated with increased linear slips and increased manual adjustments. More tilted udders (rear quarters lower than front quarters) were associated with increased liner slips and tended to be associated with increased manual adjustments. In addition, larger teat diameters and longer teats tended to be associated with increased liner slips.

Animals↗
PubMed1989

An outbreak of tuberculosis in rural Delaware.

A total of 35 patients diagnosed with tuberculosis in 1976-1984 were identified as part of a sustained outbreak involving five communities located in southern Delaware. The index case, a 25-year-old black female with sputum smear-positive, cavitary pulmonary tuberculosis, was a sexual partner of three other persons with cavitary pulmonary tuberculosis and a close contact of 10 other persons with tuberculosis. The median age of the 35 patients was 23 years (range 15 months to 77 years), and 13 (37%) were less than 15 years of age. Sixteen patients (46%) were male, and 34 (97%) were black. Pulmonary parenchymal disease was noted in 18 cases (51%), including nine (26%) with cavitary lesions; 11 (31%) had lymphatic disease (hilar and/or mediastinal); five (14%) had pleural disease; and one (3%) had a normal chest radiograph. Infection prevalence (per 100 tested) was 44.7 for close contacts of cases and 18.3 for other than close contacts, and disease prevalence (per 100 tested) was 8.9 and 1.4 for those two groups, respectively. This outbreak highlights several points: Outbreaks of tuberculosis may go undetected for several years; aggressive and complete surveillance and containment efforts are needed to control tuberculosis; and tuberculosis in children and minorities is still a problem in the United States.

Adolescent↗
PubMed1987

Computer graphics in the assessment of severity of spasmodic torticollis: potential role in the evaluation of surgical treatment.

There is a need for objective evaluation of the effectiveness of treatment of spasmodic torticollis so that comparisons can be made between different therapies. Video tape recordings of patients undergoing surgery for spasmodic torticollis were digitized and the movement of a reference marker was tracked by computer. A graphic presentation of oscillation of the marker around a mean position was obtained. Comparison of preoperative and postoperative recordings enabled assessment of the effectiveness of surgery. The results can be tabulated, facilitating accurate documentation of large series of results in publication. This should enable easier comparison of the effectiveness of different therapies.

Adult↗
PubMed1977

The effect of surgical removal of a rat sarcoma on lymphocyte cytotoxicity.

The effect of surgical removal of tumors on cytotoxicity reactions was studied in Lewis-Wister inbred rats bearing a transplantable methylcholanthrene-induced sarcoma (MCI). Lymphocyte cytotoxicity and the effect of the serum in blocking (decreasing) or potentiating (increasing) lymphocyte cytotoxicity were studied using MCI tissue culture cells, prelabeled with 3H-proline, as target cells. After surgical removal of the tumors, tumor nodules were again palpable in all rats by the seventh day after surgery and regrew at an accelerated rate. In control rats bearing the MCI sarcoma, serum blocking activity appeared between the 8th and 13th days and completely inhibited lymphocyte cytotoxicity until death of the animals. Surgical removal of the tumors resulted in a decrease in lymphocyte cytotoxicity and complete absence of serum blocking activity for at least 7 days. By the 13th day, when tumors were again growing rapidly, lymphocyte cytotoxicity had increased markedly, and blocking activity again appeared in the serum.

Animals↗