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Biomedical subjects

J R Russell

Publications and source records attributed to J R Russell.

33 records · Page 2Linked to original sources
PubMed1993

Genetic differentiation of cocoa (Theobroma cacao L.) populations revealed by RAPD analysis.

In order to preserve and exploit the valuable genetic resources of tropical forest trees, such as cocoa, a systematic assessment of the available genetic variability is necessary. The approach we have used is based on a simple mini-prep DNA extraction procedure together with a polymerase-chain-reaction- (PCR)-based polymorphic assay procedure (RAPD). Twenty-five cocoa accessions: IMCs and PAs collected from Peru and LCTEENs collected from Ecuador, which are difficult to distinguish using morphological or biochemical descriptors, were uniquely fingerprinted using a minimum of three oligonucleotide primers. Analysis of the variability detected using RAPDs clearly discriminated between the geographical origin of the three cocoa populations. Partitioning of variability into within and between population components revealed that most variation was detected within a population. The potential of RAPD analysis to facilitate the rationalization of field gene banks and provide accurate estimates of diversity to allow optimization of collecting strategies is discussed.

Base Sequence↗
PubMed1993

Effects of grazing allowance and system on the use of corn-crop residues by gestating beef cows.

Duplicate fields of corn-crop residues were grazed by 3- to 11-yr-old Charolais x Angus and Charolais x Angus x Simmental cows (average BW = 630 kg) in midgestation at allowances of .41, .82, and 1.64 ha/cow in a continuous-stocking system for 56 d in 1988 (yr 1) and 1989 (yr 2) and for 51 d in 1990 (yr 3), or at .41 ha/cow in a strip-stocking system for 56 and 51 d in yr 2 and 3, respectively. Body weight gains by cows grazing continuously stocked fields at .41, .82, and 1.64 ha/cow were -.06, -.01, and .41 kg/d (P = .02), respectively. Body weight changes by cows grazing continuously stocked and strip-stocked fields at .41 ha/cow were .15 and .30 kg/d in yr 2 and -.33 and -.53 kg/d in yr 3 (system x year, P = .08), respectively. Percentages of in vitro OM disappearance (IVOMD) of crop residues selected by ruminally fistulated steers (P = .22) and cow crop residue DMI (% of BW; P = .03) were 52.5, 1.64; 60.1, 2.87; and 61.7, 2.97 in fields continuously stocked at .41, .82, and 1.64 ha/cow after 21 to 35 d of grazing in yr 2 and 3, respectively. Selected crop residue IVOMD (P = .04) and crop residue DMI (percentage of BW, P = .07) were 58.0 and 2.46, respectively, in fields strip-stocked at .41 ha/cow. Mean yields of OM (P < .01) and IVOMD (P < .01) were 4,605, 2,136; 5,347, 2,495; and 5,761, 2,688 kg/ha in fields continuously stocked at .41, .82, and 1.64 ha/cow, respectively. Results imply that cows grazing corn-crop residues in continuously stocked fields are less likely to gain BW at grazing allowances < 1.64 ha/cow for 56 d. Differences in BW gains between cows grazing strip-stocked and continuously stocked crop residue fields were weather-dependent.

Animal Feed↗
PubMed1991

High resolution scanning of DNA autoradiographs.

The sizes of DNA fragments (alleles) on autoradiographs are measured by means of a computerised video scanner developed in this laboratory. This report investigates the advantages of using higher resolution equipment for this purpose. High resolution is simulated by using existing equipment and moving the video camera closer to the autoradiograph. Test autoradiographs, used to validate the original scanner, have been rescanned to determine the degree of improvement that could be obtained using expensive high resolution equipment.

Alleles↗
PubMed1984

The isolation and identification of vitamin D2 and vitamin D3 from Medicago sativa (alfalfa plant).

Vitamin D2 and vitamin D3 were isolated from Medicago sativa (alfalfa) grown under field and laboratory conditions and then irradiated with ultraviolet light. The vitamins were identified by ultraviolet absorption, mass spectroscopy, and comparison with synthetic standards on several chromatographic systems. Sun-cured, field-grown alfalfa contained vitamin D2 at a concentration of 48 ng/g (1920 IU/kg) and vitamin D3 at 0.63 ng/g (25 IU/kg). Laboratory-grown alfalfa, artificially irradiated, contained vitamin D2 at a concentration of 80 ng/g and vitamin D3 at 1.0 ng/g. Therefore, the presence of vitamin D2, as well as vitamin D3, has unequivocally been demonstrated in alfalfa plant tissue.

Chemical Phenomena↗
PubMed1984

A speed and frequency substandard for tachograph calibration equipment.

The process of calibrating a tachograph makes use of a mechanical head drive unit and an electronic clock tester. Both these devices should be checked against a standard at 6-month intervals. The design of such a substandard, based on a highly stable 1 MHz crystal oscillator, is described.

Accidents, Traffic↗
PubMed1981

Effect of dietary corn starch intake on ruminal, small intestinal and large intestinal starch digestion in cattle.

In Exp. 1, 24 yearling Holstein steers averaging 340 kg were fed either an alfalfa hay diet at a maintenance level of metabolizable energy (ME) intake or corn silage-corn diets at one, two or three times maintenance ME intake. After a 42-day adjustment period, steers were fed individually, and digestibilities of total alpha-glucosides, starch oligosaccharides and glucose were determined at 2-week intervals, with chromic oxide used as an indicator. Steers fed the alfalfa hay diet had higher (P less than .05) total tract digestibilities of total alpha-glucosides and starch than steers fed the corn diets. Fecal starch (percentage of dry matter) in steers fed the corn diets increased (P less than .05) from approximately 11 to 31% as level of ME intake increased from one to three times maintenance. Starch digestibilities for the corn diets fed at one, two and three times maintenance were 81.4, 76.4 and 76.0%, respectively. However, these trends toward reduced starch digestibilities were not significant. There appeared to be no apparent adaption of alpha-glucoside digestibility in the total digestive tract among steers fed different levels of corn over the intervals observed. In Exp. 2, four Holstein steers (350 KH) were each fitted with duodenal and ileal reentrant cannulas and fed either a low or a high level of corn. Alpha-glucoside intakes for animals given the low and high levels of cord averaged 1.7 and 3.2 kg, respectively. Steers fed the high level of corn digested more (p less than .05) alpha-glucoside in the total tract (2.9 vs 1.6 kg), reticulo-rumen (2.3 vs 1.2 kg) and large intestine level of corn. Steers fed the high level of corn also digested more corn in the small intestine (.415 vs .221 kg) than steers fed the lower level; however, differences were not significant. Although there were trends toward lower partial digestion coefficients (expressed as a percentage of alpha-glucoside presented to that segment) in the total tract, reticulo-rumen and small intestine for steers fed the high corn diet, the magnitude of the differences was not significant.

Animals↗
PubMed1981

Effect dietary corn starch intake on pancreatic amylase and intestinal maltase and pH in cattle.

The pH optimum of pancreatic alpha-amylase from grain-fed steers was determined to be 6.9, while that of intestinal maltase was established at 5.8. Both assays were found to be linear up to 1 hr of incubation. The V max of pancreatic amylase was determined to be pancreatic amylase was determined to be 1.15 mg of maltose monohydrate produced/hr. Activities of pancreatic and intestinal maltase were not reduced (P greater than .05) during the interval from sample collection from the animal until analysis 4 hr later when tissues were kept on ice. Twenty-four yearling Holstein steers fed either alfalfa hay at a maintenance level of metabolizable energy (ME) intake or corn at one, two or three times the maintenance ME intake level were slaughtered after being fed 106 days. The pancreas was removed alone with sections of the intestine. Specific activity of pancreatic amylase for steers fed the high level of corn was 129% of that for steers fed the alfalfa diet (P greater than .05). Intestinal maltase activity was highest in the jejunum and decreased toward the ileum. Increasing dietary starch intake resulted in no response (P greater than .05) in maltase activity at 10, 30, 50, 70, or 90% of the small intestine length. The effect of dietary starch level on dieesta pH was dependent on sampling location within the small intestine. There were no dietary effects (P greater than .05) on digesta pH for the first 10% segment of intestine distal to the pylorus. However, in all subsequent sections, digesta pH was higher steers fed the alfalfa diet than for those fed the two higher levels of grain. A calculation for estimating th amount of pancreatic amylase needed to hydrolyze starch presented to small intestine is discussed.

Amylases↗
PubMed1975

Intracerebral toxoplasmosis presenting as a mass lesion.

Intracerebral toxoplasmosis is an uncommon condition and for it a produce an intracerebral mass is rare. A case is reported in a patient also suffering from lymphosarcoma, who had received immunosuppressive therapy and who had recently had herpes zoster ophthalmica.

Brain Diseases↗
PubMedDate not supplied

Assessment of a video system for scanning DNA autoradiographs.

A video based scanning system had been developed for processing DNA autoradiographs (T. Catterick and J.R. Russell, Lab. Microcomput. (1991), in press). Before the scanner was used in casework it was necessary to assess its performance. Test DNA samples containing fragments (alleles) of known kilobase size were run against the primary (Amersham, U.K.) calibration ladder. The resulting autoradiographs were processed with the new video scanner and also using manual, ruler based measurements. Comparisons were then made between these experimental results and also with the known kilobase values quoted by the supplier of the test samples.

Autoradiography↗