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Biomedical subjects

W S Harris

Publications and source records attributed to W S Harris.

At least 73 records · Page 4Linked to original sources

Nucleus delivery.

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Cataract Extraction↗

Reduction of plasma lipids, lipoproteins, and apoproteins by dietary fish oils in patients with hypertriglyceridemia.

Dietary fish oils, which are rich in omega-3 fatty acids, have been reported to reduce plasma lipid levels in normolipidemic subjects. We examined the effects of fish oil in 20 hypertriglyceridemic patients: 10 with Type IIb hyperlipidemia and 10 with Type V. These patients were put on three diets differing primarily in fatty acid composition and fat content. The control diet contained a fatty acid mixture typical of a low-fat therapeutic diet (ratio of polyunsaturated to saturated fat, 1.4), the fish-oil diet contained omega-3 fatty acids, and the vegetable-oil diet was rich in the omega-6 fatty acid, linoleic acid. Each diet was followed for four weeks. In the Type IIb group, the fish-oil diet led to decreases in both plasma cholesterol (-27 per cent) and triglyceride (-64 per cent), as compared with the control diet. Very-low-density lipoproteins (VLDLs) were also reduced markedly. The vegetable-oil diet had much less effect. With fish oil, the Type V group had marked decreases in total cholesterol and triglyceride levels (-45 and -79 per cent, respectively). VLDL levels were dramatically lowered, as were apoprotein E levels. The vegetable-oil diet (unlike the fish-oil diet) produced a rapid and significant rise in plasma triglyceride levels. We conclude that fish oils and fish may be useful components of diets for the treatment of hypertriglyceridemia.

Adult↗

Management of the posterior capsule before and after the YAG laser.

A retrospective chart review of 2,514 consecutive posterior chamber implants was carried out to assess the management of the posterior capsule when vision loss dictated intervention. The capsulotomy technique used between May 1977 and March 1983 was pars plana posterior capsulotomy (227 eyes). All posterior capsulotomies performed after April 1, 1983 were with the YAG laser (342 eyes). Comparison of the complications with the two methods showed considerable differences. Anterior segment problems appear greater following YAG laser posterior capsulotomy than pars plana posterior capsulotomy, whereas posterior segment complications appear similar in both techniques. Comparison of CME following both techniques indicates that a delay of 6 months or more between cataract surgery and posterior capsulotomy is advisable.

Cataract Extraction↗

Dietary omega-3 fatty acids prevent carbohydrate-induced hypertriglyceridemia.

Dietary fish oils rich in omega-3 fatty acids are remarkably hypotriglyceridemic in both normal and hypertriglyceridemic subjects. This present study was designed to examine the hypothesis that dietary fish oils could prevent the usual sharp increase in plasma triglyceride and very low-density lipoprotein (VLDL) levels that occur physiologically after the induction by a high-carbohydrate diet. Seven healthy volunteers consumed three experimental liquid formula diets: the baseline diet (45% fat, 10% protein, 45% carbohydrate) and two high-carbohydrate diets (15% fat, 10% protein, 75% carbohydrate), one as a control diet and the other containing fish oil. The baseline and control dietary fats were a mixture of peanut oil and cocoa butter, whereas the fish oil diet contained high levels of omega-3 fatty acids. The plasma triglyceride levels rose from 105 mg/dL during baseline diet to 194 mg/dL during the high-CHO control diet (P less than 0.005). VLDL triglyceride levels increased from 69 to 156 mg/dL (P less than 0.005) and VLDL cholesterol from 18 to 34 mg/dL (P less than 0.005). When fish oil was substituted for the control fats, plasma triglyceride levels fell from 194 to 75 mg/dL (P less than 0.005), VLDL triglyceride and cholesterol levels were reduced from 156 to 34 mg/dL (P less than 0.005) and from 34 to 12 mg/dL (P less than 0.005), respectively. These effects were noted by two to three days after beginning the fish oil diet. Thus, dietary omega-3 fatty acids from fish oil rapidly and markedly reduced VLDL triglyceride levels even in the face of a high-carbohydrate diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Will dietary omega-3 fatty acids change the composition of human milk?

The most abundant long-chain polyunsaturated fatty acid in brain and retinal lipids is docosahexaenoic acid (DHA, C22:6 omega 3). It becomes incorporated into nerve tissues mostly in utero and during the 1st yr of life. DHA is derived in humans either performed in the diet or by hepatic synthesis from dietary linolenic acid (C18:3 omega 3). Since human milk contains DHA, this study was designed to see if increased dietary DHA would be reflected in a higher DHA content in human milk. Eight lactating women were given supplements of a fish oil concentrate rich in omega-3 fatty acids, including DHA (11% of fatty acids). Six women took 5 g/day of fish oil for 28 days; five women consumed 10 g/day for 14 days; and one woman consumed 47 g/day for 8 days. Each intake level of fish oil produced significant dose-dependent increases in the DHA content of milk and plasma. Base-line DHA levels in milk were 0.1 +/- 0.06% of total fatty acids. Five g/day of fish oil raised the levels to 0.5 +/- 0.1% (p less than 0.001); 10 g/day raised DHA levels to 0.8 +/- 0.1% (p less than 0.001); and 47 g/day produced DHA levels of 4.8%. The results of this study indicated that relatively low intakes of dietary DHA significantly elevated milk DHA content. This would clearly elevate the infant's DHA intake and might have implications for brain and retinal development.

Adult↗

The comparative reductions of the plasma lipids and lipoproteins by dietary polyunsaturated fats: salmon oil versus vegetable oils.

The lower plasma lipid levels and lower incidence of atherosclerotic diseases in Greenland Eskimos suggested that the unusual fatty acids present in their diet of seal and fish may be anti-atherogenic. These fatty acids are eicosapentaenoic (C20:5) and docosahexaenoic (C22:6) acids and are of the omega-3 fatty acid family. We have compared a salmon oil diet containing high levels of these unique fatty acids to a control diet high in saturated fat and to a vegetable oil diet high in linoleic acid (C18:2). All diets contained 40% of the total calories as fat and 500 mg of cholesterol; they differed only in fatty acid composition. In 4 wk the salmon oil diet reduced plasma cholesterol levels from 188 to 162 mg/dl (p less than 0.001) and triglyceride levels from 77 to 48 mg/dl (p less than 0.005). LDL and VLDL cholesterol levels changed from 128 to 108 and 13 to 8 mg/dl (p less than 0.005), respectively. HDL cholesterol levels did not change. The vegetable oil diet caused similar decreases in cholesterol levels but did not lower triglyceride levels. The omega-3 fatty acids comprised up to 30% of the total fatty acids in each plasma lipid class after the salmon diet. Fish oils contain fatty acids which may be metabolically unique and potentially useful in the control of both hypercholesterolemia and hypertriglyceridemia.

Adult↗

Secondary and exchange posterior chamber lens implantation.

A retrospective chart review of 34 secondary or exchange posterior chamber lens implantations was performed. Overall 94% of the patients achieved a visual acuity of 20/40 or better at six to 12 months postoperative. Associated intraoperative procedures included lens implant removal for exchange (50%), iris suture (41%), posterior capsule polishing (24%) or discussion (24%), and anterior vitrectomy (15%). The postoperative complications included retinal detachment (6%), persistent clinical cystoid macular edema (3%), posterior capsular opacification (3%), failure to fixate requiring iris suture (3%), hyphema (3%), and pupil capture (3%). Secondary and exchange posterior chamber lens implantation can be performed with satisfactory visual acuity results but there is a real rate of complication that needs to be considered by the surgeon and patient who is contemplating the operation.

Adult↗

Heart rate response to cough.

It was hypothesized that the chronotropic response to intrathoracic pressure changes generated by cough may provide a reliable and rapid index of the cardioacceleratory capacity, a complex reflex response important for survival. In 27 adults in the supine position we measured the heart rate response following three forceful coughs performed over a 3-s period. At approximately four beats after the last cough, the mean instantaneous heart rate rose from 72 +/- 3 (SE) (range 54-91) to 94 +/- 5 beats/min (range 71-115), resulting in a maximal rate change of 31 +/- 3% (P less than 0.001). The time course and magnitude of response were reproducible within and similar among the subjects. Thus the heart rate response to large intrathoracic pressure transients generated by cough provides a quantitative and noninvasive estimate of integrity of the capacity for cardiac acceleration.

Adult↗

Combined penetrating keratoplasty, extracapsular cataract extraction, and posterior chamber lens implantation.

A retrospective chart review of 18 consecutive unselected cases of combined penetrating keratoplasty, extracapsular cataract extraction, and posterior chamber lens implantation was performed. Overall, 89% of the grafts remained clear with follow-up between six and 54 months (average 21 months). Visual acuities were 20/50 or better in 61% of the cases and 20/80 or better in 83%. Postoperative complications included two graft failures, two cases of secondary glaucoma, one case of cystoid macular edema, and one case of pupil capture. No patients to date have required a secondary discission.

Aged↗

The effects of dietary omega 3 fatty acids on platelet composition and function in man: a prospective, controlled study.

The rarity of atherosclerotic vascular disease and a mild bruising tendency in Greenland Eskimos has been linked to their ingestion of omega 3 fatty acids contained in foods obtained from the sea. Previous studies have shown that feeding salmon oil to normal volunteers resulted in reductions of plasma cholesterol and triglycerides. We wished to learn whether salmon oil feeding would result in the incorporation of omega 3 fatty acids into platelets and whether platelet function or platelet-vessel interaction would be altered. Diets containing salmon oils led to the incorporation of eicosapentaenoic acid (C20:5 omega 3) into platelets (6.1%) with a reduction in arachidonic acid (C20:4 omega 6). The ratio of C20:5/C20:4 increased from 0.0045 on the control diet to 0.3 on the salmon diet. Bleeding times were prolonged (from 6.75 to 10 min, p less than 0.005), platelet retention on glass beads was mildly reduced (from 89% to 78%, p less than 0.0005), and platelet aggregation in response to dilute concentrations of ADP was inhibited in the subjects ingesting the salmon oil. We conclude that in normal subjects dietary omega 2 fatty acids derived from salmon oil are incorporated into platelet phospholipids and that these changes are accompanied by alterations in bleeding time and platelet function.

Adenosine Diphosphate↗

Management of the posterior capsule following posterior chamber lens implantation.

A retrospective review of posterior capsule management in 595 consecutive unselected posterior chamber lens implants performed between 10/1/76 and 9/30/79 is presented. The incidence of secondary discission required increased from 0.6%, in cases with zero to six months follow-up, to 18.4%, in cases with 24 to 36 months follow-up, to 18.4%, in cases with 24 to 36 months follow-up. A plano-convex posterior chamber lens design which allows the convex surface of the implant to contact the posterior capsule reduced the incidence of posterior capsule opacification by providing a barrier to cortical cell migration. When secondary discission is needed behind a posterior chamber lens, it may be performed successfully using a pars plana approach. Our data suggest that the incidence of the major complications of this technique, i.e. cystoid macular edema and retinal detachment, may be reduced by delaying capsulotomy for 12 months after implant surgery.

Humans↗