PubMed Health⌕ Search

Biomedical subjects

J R Sargent

Publications and source records attributed to J R Sargent.

At least 55 records · Page 3Linked to original sources

Effects of time-in-clinic, clinic setting, and faculty supervision on the continuity clinic experience.

STUDY OBJECTIVE: To evaluate the effects of setting, type of supervision, and time in clinic on the resident continuity clinic experience. DESIGN: Prospective cohort with preintervention and postintervention measures. SETTINGS: Pediatric residents selected one of three clinic settings for their continuity clinic experience. These included a traditional, university-based clinic, private practice offices, and publicly funded community-based clinics. SUBJECTS: All pediatric residents at the University of Utah Health Sciences Center, July 1985 through June 1991. INTERVENTIONS: Using varied clinic sites, matching residents one or two to one with preceptors for their continuity clinic, increasing continuity clinic from 1 to 2 half-days per week. MEASUREMENTS AND MAIN RESULTS: Residents in private offices had the most varied experience, seeing more patients, more acute care, and a broader age range of patients than residents at other sites. They were more likely both to be observed by their preceptors during patient visits and to observe their preceptors delivering care. Because the number of patients seen per session rose, increasing continuity clinic time from one to two half-days per week more than doubled the number of patients seen per week. Increased time away from hospital did not affect scores on the Pediatric In-Training Examination. While test scores were similar for incoming residents, those in private offices scored higher on the final Behavioral Pediatrics Examination (P < .05). CONCLUSIONS: Clinic setting, time in clinic, and faculty supervision affect the quality of the continuity clinic experience. Increased time in clinic resulted in a broader exposure to patients. Residents placed in private offices had a more varied patient mix, were more closely supervised, and seemed to gain primary care skills more rapidly than residents at other sites.

Clinical Competence↗

Effects of exogenous monounsaturated fatty acids on fatty acid metabolism in cultured skin fibroblasts from adrenoleukodystrophy patients.

The conversion of [1-14C]16:0 to very-long-chain saturated fatty acids (VLCSFA) was greater in fibroblasts from adrenoleukodystrophy (ALD) patients than fibroblasts from normal subjects. Added 23:1(n-9) decreased the formation of VLCSFA from [1-14C]16:0 in ALD fibroblasts to the value found in normal fibroblasts. Chain-elongation as well as extensive chain-shortening of added 20:1(n-9), 22:1(n-9), 23:1(n-9) and 24:1(n-9) occurred in both normal and ALD fibroblasts, with chain-shortening being less in ALD than in normal fibroblasts. Added 18:1(n-9) together with 22:1(n-9) reduced the levels of both VLCSFA and total n-6 and n-3 polyunsaturated fatty acids (PUFA) in normal and ALD fibroblasts. The levels of total (n-6) and (n-3) PUFA but not the levels of VLCSFA were readily restored by culturing the cells in the presence of 18:1(n-9), 22:1(n-9), 18:2(n-6) and 18:3(n-3). The results are consistent with added monounsaturated fatty acids reducing levels of VLCSFA in ALD fibroblasts by depressing their biosynthesis from 16:0. They also support the use of oils rich in long chain monoenes as a dietary therapy for ALD patients but caution that the PUFA status of ALD patients should be monitored with a view to dietary supplementation, if necessary, with PUFA.

Adrenoleukodystrophy↗

Direct effects of temperature on phospholipid and polyunsaturated fatty acid metabolism in isolated brain cells from rainbow trout, Oncorhynchus mykiss.

1. The direct effects of temperature on the metabolism of [1-14C]18:2(n-6), [1-14C]18:3(n-3), [1-14C]20:4(n-6) and [1-14C]20:5(n-3) were studied in isolated brain cells from rainbow trout, Oncorhynchus mykiss. 2. Recovery of radioactivity from all the polyunsaturated fatty acids (PUFA) in total lipid was significantly greater at 5 and 15 degrees C than at 25 degrees C. 3. The lower incubation temperatures decreased the relative net incorporation of all the 14C-labelled PUFA into phosphatidylcholine (PC) and increased the relative incorporation of the PUFA into the other phosphoglycerides, especially phosphatidylethanolamine (PE). 4. The effects on PC were generally more significant between 25 and 15 degrees C, whereas the effects on PE were generally significant both between 25 and 15 degrees C and between 15 and 5 degrees C. 5. This suggests that the lysophospholipid acyltransferases responsible for the incorporation of PUFA into different phosphoglycerides may have differential sensitivities to temperature. 6. In contrast, the acyltransferase activities showed fatty acyl preferences that were independent of temperature. 7. Although a trend towards decreased activity at 5 degrees C was apparent, temperature generally had little significant effect on the relative percentages of the PUFA metabolized via the desaturase pathways.

Acclimatization↗

Effects of increasing dietary linoleic acid on phospholipid fatty acid composition and eicosanoid production in leucocytes and gill cells of Atlantic salmon (Salmo salar).

Diets containing linoleic acid at 10, 25 and 45% of total dietary fatty acids were fed to three groups of post-smolt Atlantic salmon (Salmo salar) for 18 weeks. Incorporation of linoleic acid into membrane phospholipids of leucocytes and gills increased in response to dietary intake. In general, there was an increase in arachidonic acid and a decrease in eicosapentaenoic acid in the individual phospholipids of both cell types in response to increasing dietary linoleic acid. These changes in eicosanoid precursors were reflected in significantly increased plasma concentrations of 6-keto-PGF1 alpha and TXB2 in salmon given the highest dietary linoleic acid. In whole blood stimulated with the calcium ionophore A23187, LTB4, 12-HETE and TXB2 were significantly increased and 12-HEPE significantly decreased in response to increasing dietary linoleic acid. In isolated gill cells stimulated with A23187, 12-HEPE, 12-HETE, 14-HDHE and TXB2 were all decreased in response to increasing dietary linoleic acid, although the ratio of 12-HEPE/12-HETE was also decreased.

6-Ketoprostaglandin F1 alpha↗

High dietary linoleic acid affects the fatty acid compositions of individual phospholipids from tissues of Atlantic salmon (Salmo salar): association with stress susceptibility and cardiac lesion.

For 16 wk Atlantic salmon (Salmo salar) post-smolts were fed practical-type diets that contained either fish oil (FO) or sunflower oil (SO) as the lipid component. Both diets contained adequate (n-3) polyunsaturated fatty acids (PUFA). All the phospholipids of heart and liver from SO-fed fish had increased levels of 18:2(n-6), 20:2(n-6) and 20:3(n-6); phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) also had increased 20:4(n-6). There was a general decrease in 20:5(n-3) in the phospholipids, reflected in an increase in the 20:4(n-6)/20:5(n-3) ratio, especially in PC and PE. The fatty acid compositions of phospholipids from brain and retina were much less affected by dietary linoleate than those of heart and liver. Fish fed SO developed severe heart lesions that caused thinning of the ventricular wall and muscle necrosis. The fish fed SO also were susceptible to a transportation-induced shock syndrome that caused 30% mortality. These results establish that a diet with a low (n-3)/(n-6) ratio can cause changes in fatty acid metabolism that are deleterious to the health of salmonid fish, especially when subjected to stress.

Animals↗

Incorporation of [3H]arachidonic and [14C]eicosapentaenoic acids into glycerophospholipids and their metabolism via lipoxygenases in isolated brain cells from rainbow trout Oncorhynchus mykiss.

The incorporation of [3H]arachidonate [( 3H]AA) and [14C]eicosapentaenoate [( 14C]EPA) into glycerophospholipids was studied in isolated brain cells from rainbow trout, a teleost fish whose lipids are rich in (n-3) polyunsaturated fatty acids (PUFAs). EPA was incorporated into total lipid to a greater extent than AA, but the incorporation of both PUFAs into total glycerophospholipids was almost identical. The incorporation of both AA and EPA was greatest into phosphatidylethanolamine (PE). However, when expressed per milligram of individual phosphoglycerides, both AA and EPA were preferentially incorporated into phosphatidylinositol (PI), the preference being significantly greater with AA. On the same basis, significantly more EPA than AA was incorporated into phosphatidylcholine (PC). When double-labelled cells were challenged with calcium ionophore A23187, the 3H and 14C released from the cells closely paralleled each other, peaking at 10 min after addition of ionophore. The 12-monohydroxylated derivative was the pre-dominant lipoxygenase product from both AA and EPA with a rank order of 12-hydroxyeicosatetraenoic acid (12-HETE) greater than leukotriene B4 (LTB4) greater than 5-HETE greater than 15-HETE for the AA products and 12-hydroxyeicosapentaenoic acid (12-HEPE) greater than 5-HEPE greater than LTB5 greater than 15 HEPE for EPA products. The 3H/14C (dpm/dpm) ratios in the glycerophospholipids, total released radioactivity, and the lipoxygenase products suggested that PC rather than PI was the likely source of eicosanoid precursors in trout brain cells.

Animals↗

Resident training in community pediatricians' offices. Not a financial drain.

There are numerous disadvantages to teaching ambulatory pediatrics in hospital-based clinics. The present study evaluated the economic impact on community pediatricians' practices that served as continuity experience sites for pediatric residents by using an apprenticeship model. The number of patients seen and the dollars billed by the presence of a resident, even though these preceptors provided significantly more supervision to residents than that received by residents in hospital-based clinics. Furthermore, residents billed substantial revenues for preceptor practices. This approach to teaching general pediatrics is economically viable, providing resident stipends are not dependent on fees generated by patient visits.

Humans↗

Incorporation into phospholipid classes and metabolism via desaturation and elongation of various 14C-labelled (n-3) and (n-6) polyunsaturated fatty acids in trout astrocytes in primary culture.

The incorporation and metabolism of [1-14C]18:3(n-3), [1-14C]20:5(n-3), [1-14C]18:2(n-6), and [1-14C]20:4(n-6) were studied in primary cultures of trout brain astrocytes. There were no significant differences between the amounts of individual fatty acids incorporated into total lipid at 22 degrees C, with greater than 90% of all the fatty acids being incorporated into polar lipid classes. The distributions of 18:2(n-6), 18:3(n-3), and 20:5(n-3) in individual phospholipid classes at 22 degrees C were very similar, with 57-63 and 18-24% being incorporated into phosphatidylcholine and phosphatidylethanolamine, respectively. Approximately equal amounts of 20:4(n-6), approximately 30% of the total, were incorporated into each of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol. The metabolism of the (n-3) fatty acids to longer-chain and more unsaturated species was significantly greater than that of (n-6) acids, but delta 4-desaturase activity was very low. A culture temperature of 10 degrees C increased the incorporation of all the fatty acids into total lipid and that of C20 fatty acids into polar lipid. At 10 degrees C, the incorporation of C20 fatty acids into phosphatidylethanolamine and phosphatidylinositol was increased, and the incorporation into phosphatidylcholine and phosphatidylserine was decreased. The distribution of C18 fatty acids was unchanged at the lower temperature, as was the desaturation and elongation of all the polyunsaturated fatty acids incorporated.

Animals↗

Polyunsaturated fatty acid metabolism in fish cells: differential metabolism of (n-3) and (n-6) series acids by cultured cells originating from a freshwater teleost fish and from a marine teleost fish.

1. The incorporation and metabolism of (n-3) and (n-6) polyunsaturated fatty acids (PUFA) supplemented to growing cultures were studied in rainbow trout (RTG-2) and turbot (TF) cell lines. 2. A fatty acid concentration of 20 microM considerably altered the fatty acid composition of the cells without affecting lipid class composition or the appearance of cytoplasmic lipid droplets. 3. Both cell lines exhibited considerable delta 6 desaturase activities. 4. Whereas delta 5 desaturase activity was expressed in RTG-2 cells, delta 4 desaturase activity was absent and, conversely, delta 4 desaturase activity was expressed in TF cells, but there was an apparent deficiency in the C18 to C20 elongase multi-enzyme complex. 5. The delta 6 desaturase activity in both cell lines showed little preference between 18:2(n-6) and 18:3(n-3) but the delta 5 desaturase activity of RTG-2 cells and the delta 4 desaturase activity of TF cells showed a preference for (n-3)PUFA. 6. Two fish oil concentrates were assessed for their ability to generate fatty acid compositions in the cell lines more closely resembling those of intact fish tissues.

Animals↗

Effects of the fatty acid composition of phosphatidylserine and diacylglycerol on the in vitro activity of protein kinase C from rat spleen: influences of (n-3) and (n-6) polyunsaturated fatty acids.

Protein kinase C from rat spleen was assayed with different phosphatidylserines (PtdSer) and diacylglycerols (DAG): PtdSer from bovine brain containing 0.8% 20:4 (n-6), 1.0% 20:5 (n-3) and 5.7% 22:6 (n-3); PtdSer from trout liver lacking 20:4 (n-6) and containing 0.6% 20:5 (n-3) and 43% 22:6 (n-3); 1-stearoyl-2-arachidonylglycerol prepared from synthetic 1-stearoyl-2-arachidonyl-sn-glycero-3-phosphocholine; DAG, prepared from cod roe phospholipids, containing 2.1% 20:4 (n-6), 11.7% 20:5 (n-3) and 29.0% 22:6 (n-3); 1,2-dioleoylglycerol. When assayed with Ca2+ in the absence of DAG there was no difference in the activity of protein kinase C between the two PtdSer. When assayed with Ca2+ in the absence of PtdSer the (n-6)-rich DAG was 2 fold more active, and the (n-3)-rich DAG 1.3 fold more active than 1,2-dioleoylglycerol. When assayed in the presence of both PtdSer and DAG, the enzyme was equally active with all of the DAG, but was 1.3 fold more active with the PtdSer from bovine brain than with the PtdSer from trout liver.

Animals↗

The effect of calcium ionophore A23187 on the metabolism of arachidonic and eicosapentaenoic acids in neutrophils from a marine teleost fish rich in (n-3) polyunsaturated fatty acids.

1. [1-14C]AA and [1-14C]EPA were incorporated equally into plaice neutrophil phospholipids. 2. Incubation with A23187 resulted in the loss of label from total phospholipids and increased label released from the neutrophils. 3. Labelled LTB4 and LTB5 production was increased 2.5- and 3-fold, respectively, by A23187 treatment. 4. However, the incorporated AA was generally more metabolically active than the incorporated EPA with approx. 3-4 times as much LTB4 produced than LTB5 by cells in the presence or absence of A23187, respectively. 5. The results obtained in this (n-3) PUFA-rich species were discussed in comparison with current knowledge of AA and EPA metabolism in mammalian neutrophils.

Animals↗

Protein kinase C activity in the spleen of trout (Salmo gairdneri) and the rectal gland of dogfish (Scyliorhinus canicula), and the effects of phosphatidylserine and diacylglycerol containing (n-3) polyunsaturated fatty acids.

1. High speed supernatant fractions of trout spleen and dogfish rectal gland contained 22.5 and 7.2 nmol/min/g tissue of protein kinase C activity respectively. 2. The effect of Ca2+ concentration on the activities with phosphatidylserine (PtdSer) alone, diacylglycerol (DAG) alone and PtdSer and DAG together were determined. Both enzymes required Ca2+ but activity was independent of Ca2+ concentration within the physiological range of 0.1-10 microns. 3. The effect of PtdSer and DAG containing (n - 3) polyunsaturated fatty acids (PUFA) on the activity of protein kinase C from both tissues was examined. Both enzymes were active with all lipids tested and showed little or no discrimination between lipids differing in their contents of (n-3) or (n-6) polyunsaturated fatty acids.

Animals↗

Incorporation of [1-14C]arachidonic and [1-14C]eicosapentaenoic acids into the phospholipids of peripheral blood neutrophils from the plaice, Pleuronectes platessa L.

The incorporation of [1-14C]arachidonic acid and [1-14C]eicosapentaenoic acids into phospholipids was studied in peripheral blood neutrophils from plaice, a marine fish whose lipids are rich in (n-3) polyunsaturated fatty acids. The incorporation of both labelled fatty acids into phospholipids was approximately equal when presented individually, and at equal concentration, to the cells. Arachidonic acid was relatively preferred when both acids were present in the incubations. When incorporation was expressed per unit mass of phospholipid class, the order of incorporation was PI greater than PC greater than PE greater than PS greater than sphingomyelin for both fatty acids. However, the specificity for incorporation into PI was significantly greater with arachidonic acid. Eicosapentaenoic acid was incorporated into PC to a greater extent than arachidonic acid. The results are discussed in relation to the possible roles of arachidonic acid and eicosapentaenoic acid in polyunsaturated fatty acid metabolism in plaice neutrophils.

Animals↗

The role of polyunsaturated fatty acids in fish.

The physical properties of polyunsaturated and saturated fatty acids are compared in relation to melting points and fluidity. The role of polyunsaturated fatty acids on membrane fluidity and membrane bound enzyme activity is discussed. The influence of the environment, particularly temperature, on poikilothermic animals is considered in relation to membrane fatty acid composition and metabolism. The metabolic role of polyunsaturated fatty acids of the (n-3) series and their interaction with arachidonate metabolism is discussed.

Animals↗

Utilization of porcine pancreatic phospholipase A2 for the preparation of a marine fish oil enriched in (n - 3) polyunsaturated fatty acids.

A simple and rapid method is described for the preparation of a marine oil fraction highly enriched in (n - 3) polyunsaturated fatty acids. Cod roe, containing lipid up to 15% of its dry weight, approximately 70% of which is phospholipid, was the starting material. Incubation of a concentrated aqueous extract of the roe with porcine pancreatic phospholipase A2 (EC 3.1.1.4) was the key step in the procedure. Extraction of the freeze-dried reaction product with diethyl ether containing formic acid produced an oil in a yield of 1.0 g/100 g wet wt of starting roe. The oil contained over 95% as free fatty acids, with 20:5 (n - 3) and 22:6 (n - 3) accounting for up to 24 and 40%, respectively, of the total free fatty acids. The therapeutic use of the oil is mentioned.

Animals↗