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D W Alexander

Publications and source records attributed to D W Alexander.

12 recordsLinked to original sources
PubMed1997

Fish oil source differentially affects rat immune cell alpha-tocopherol concentration.

We have previously reported that both the source of dietary fish oil and the chemical form of vitamin E supplied in the diet affect the vitamin E status of immune cells in rats. The purpose of this study was to investigate further the effect of fish oil source on immune cell vitamin E status using free alpha-tocopherol (alpha-T) at the AIN recommended level as the sole source of vitamin E. Sixty weanling female rats were fed semipurified, high fat (20 g/100 g) diets containing either tocopherol-stripped lard (LRD), menhaden fish oil (MFO), sardine fish oil (SRD) or cod liver oil (CLO) as the primary lipid source. Endogenous alpha-T concentration was measured and equalized to 150 mg/kg oil by addition of free RRR-alpha-T to each lipid source, allowing for a final concentration of alpha-T in the mixed diet of 30 mg/kg. An additional group of rats was fed LRD without supplemental vitamin E (LRD-) as a negative control. After feeding experimental diets for 5 or 10 wk, tissues were collected for alpha-T analysis by HPLC. After 5 wk, plasma and liver alpha-T (micromol alpha-T/g lipid) were significantly lower in SRD- and CLO-fed rats compared with LRD-fed rats. At 10 wk, only plasma alpha-T in CLO-fed rats remained significantly depressed. Plasma and liver alpha-T concentrations (micromol alpha-T/g lipid) were not significantly lower in MFO-fed rats than LRD-fed rats at either time point. Compared with LRD, feeding MFO to rats for 5 or 10 wk resulted in significantly greater alpha-T content of immune cells. In similar fashion, SRD-fed rats, compared with LRD-fed rats, also had significantly greater alpha-T content in splenocytes at both time points and greater thymocyte alpha-T at 10 wk. In all instances, the alpha-T status of rats fed CLO was indistinguishable from that of rats fed the vitamin E-free diet (LRD-). These data further demonstrate the complexity of the relationship between vitamin E status and dietary (n-3) polyunsaturated fatty acids (PUFA).

Animals↗
PubMed1995

Fish oils lower rat plasma and hepatic, but not immune cell alpha-tocopherol concentration.

These studies were designed to measure the impact of different fish oil sources of dietary (n-3) polyunsaturated fatty acid on the alpha-tocopherol content of rat immune cells. In the first experiment, rats were fed diets containing either lard, corn oil, menhaden fish oil or cod liver oil. In the second study, sardine fish oil replaced corn oil. Dietary fat source did not significantly influence body weights or the yield of immune cells in either study. In both studies, plasma and liver alpha-tocopherol concentrations were significantly lower in (n-3) polyunsaturated fatty acid-fed rats than in rats fed lard. In the first study, immune cell alpha-tocopherol concentrations followed those observed in the plasma and liver. These concentrations closely paralleled the amount of RRR-alpha-tocopheryl acetate added to diets and not the total vitamin E present, which was the same for all treatment groups. However, in the second study, alpha-tocopherol concentration of immune cells was not significantly different among rats fed lard, menhaden fish oil, and sardine fish oil. In that study both the amount and form of vitamin E were carefully balanced across dietary treatment groups. In conclusion, despite having similar amounts of (n-3) polyunsaturated fatty acids, two out of three fish oils tested did not lower immune cell alpha-tocopherol concentration even in the face of significantly reduced plasma and liver alpha-tocopherol concentrations.

Animals↗
PubMed1993

Maternally-supplied fish oil alters piglet immune cell fatty acid profile and eicosanoid production.

This study was designed to examine the incorporation of omega-3 (n-3) fatty acids into the immune tissues of pigs nursing fish oil-fed sows and to determine the effect of maternal dietary n-3 consumption on in vitro immune cell eicosanoid production. On day 107 of gestation, 12 sows were randomly allotted to a diet containing either 7% menhaden fish oil (MFO) or lard (LRD). The fatty acid profile of serum, liver, thymus, splenocytes and alveolar macrophages (AM) of 18-21-day-old pigs was significantly affected by the fat source provided to the sow. Arachidonic acid (20:4n-6) content was typically reduced by more than 50% in MFO as compared with LRD pigs. In MFO pigs, eicosapentaenoic acid (20:5n-3) was the major n-3 polyunsaturated fatty acid, and its levels matched or exceeded those of arachidonic acid. Basal release of prostaglandin E, thromboxane B and leukotriene B by AM was 60-70% lower in MFO vs. LRD pigs. However, when these immune cells were stimulated with calcium ionophore A23187, release of leukotriene B was similar in MFO and LRD pigs. In conclusion, substituting MFO for LRD in a sow's late-gestation and lactation diet greatly elevated the content of n-3 fatty acids in the nursing pig immune cells and generally reduced in vitro eicosanoid release by pig immune cells.

Animals↗
PubMed1988

A clinical trial of timolol and epinephrine in the treatment of primary open-angle glaucoma.

Forty-seven patients with chronic open-angle glaucoma who required therapy but who had never been treated previously were enrolled in a prospective randomized, long-term clinical trial comparing the effectiveness of 0.5% timolol maleate and 1% epinephrine. Patients were followed for an average of 33 months. There were 20 failures, 18 of which were because of inadequate intraocular pressure (IOP) control (required 20% reduction in outflow pressure). Twelve failures were in the epinephrine group and eight were in the timolol group. During the first year of therapy, 35% compared with 0% of patients failed in the epinephrine and timolol groups, respectively (P less than 0.01). During the later years of the study, the failure rates in the two groups were similar. The results suggest that timolol is superior to epinephrine during the first year of therapy, and likely as effective as epinephrine in the long-term treatment of glaucoma.

Aged↗
PubMed1988

Cell density dependency of vitreous fibrosis induced by monocytes and lymphocytes.

The possible roles of monocytes and lymphocytes in vitreous fibrosis were examined by injecting various numbers of the peripheral cell types into the rabbit vitreous. Our results indicated that the degree of vitreous fibrosis and the presence of traction retinal detachment corresponded to the number of cells injected. It was suggested that these findings are probably similar to vitreous membrane formation and retinal detachment in various clinical ocular diseases or inflammations in humans.

Animals↗
PubMed1985

Change in vitreous collagen after penetrating injury.

Following controlled ocular penetrating injuries in rabbits, autologous blood was injected into the vitreous. All animals were examined with ultrasonography, ophthalmoscopy and photography. After 3 weeks the animals were sacrificed and serial histologic sections were made on the enucleated globes. Fibroblasts and collagen were found in the vitreous. In additional eyes, the altered vitreous was removed and examined by gel electrophoresis following limited pepsin digestion. Type I collagen was an important component of vitreous fibrosis. In contrast, only type II collagen was detected in normal vitreous. The collagen formation after hemorrhagic injury may follow a similar process of wound healing in other tissues.

Animals↗
PubMed1982

Decelerated synthesized speech as a means of shaping speed of auditory processing of children with delayed language.

This study investigated whether the rate at which children with delayed language process auditory stimuli can be increased through a process of shaping with synthesized speech stimuli. Results indicate that stimuli with slowed down critical formant cues were easier for these 24 children with delayed language to discriminate and that training with stimuli of extended duration did generalize to stimuli of normal durations. Implications of these findings and usefulness of this methodology are discussed.

Child↗
PubMed1979

Communication skills and undergraduate medical education.

This paper reports some aspects of teaching communication skills based on experience with over 100 pre-clinical students in each of two years. Students interviewed patients selected by general practitioner tutors from their practices and 214 interviews, recorded on videotape, were subsequently analysed. Without having been given detailed instruction, approximately two-thirds of each class of second year students (mean age 19 1/2 years) sustained a consultation for 5 minutes or more. Over one half of the students elicited the salient features of the patients' problems within this short time. Anxiety exhibited by the majority of students could be seen to influence the interviews in several ways. These manifestations and the ways in which the interview was affected are briefly described. When some of the patients were subsequently interviewed by postgraduate trainees in general practice, the consultations differed in a number of respects. These differences are described, and the possible significance of the observations is discussed in relation to medical education.

Anxiety↗