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Biomedical subjects

J D Cook

Publications and source records attributed to J D Cook.

At least 181 records · Page 10Linked to original sources
PubMed1979

Food iron absorption in human subjects. V. Effects of the major dietary constituents of semisynthetic meal.

Studies were performed in adult volunteer subjects to determine the effect on nonheme iron absorption of protein, carbohydrate, and fat. These constituents were administered as egg albumin, dextrimaltose, and corn oil, respectively, in a semisynthetic meal containing 700 kcal and 4.1 mg iron. Because any one of these ingredients are unpalatable when administered alone, their effect was determined by serially deleting or doubling their content in the basal semisynthetic meal. With both approaches, carbohydrate and fat had little influence whereas egg albumin had a significant inhibitory effect on the absorption of nonheme iron.

Absorption↗
PubMed1979

Absorption of monoferric phytate by dogs.

Recent studies have shown that the iron in wheat is predominantly in the form of monoferric phytate (MFP). Unlike phytate complexed with two or more iron atoms, MFP is soluble at pH 7.0 and above and may therefore be a relatively available form of dietary iron. To examine this point, we tested iron absorption in adult dogs using a double radioisotope method and total body counting. When given without food, MFP was about one-half as available as ferrous sulphate at an iron-equivalent dose of 1.5 mg and only about one-seventh as available at a dose of 15 mg iron. When administered with food, MFP underwent complete isotopic exchange with the nonheme pool of dietary iron. When added to meals of either high or low iron availability in amounts that might be used for iron fortification, the absorption was the same for MFP iron as for the major pool of dietary inorganic iron.

Animals↗
PubMed1979

Lymphoblastic transformation in response to viral antigens in multiple sclerosis.

The blastogenic response of lymphocytes to pokeweed mitogen and a battery of viral antigens was studied in healthy individuals, patients with multiple sclerosis (MS), and patients with other neurologic disorders. The multiple sclerosis patients exhibited a diminished response to pokeweed mitogen and to mumps, parainfluenza, and poliomyelitis I antigens when compared with healthy individuals. However, there was no significant difference between the multiple sclerosis patients and the neurologic control group, except that the MS patients had a better response to measles antigen. The three groups did not differ with regard to herpes antigen. Blocking factors were found in the autologous plasma of all three groups with approximately equal frequency, but were not responsible for the decreased responses noted. A significant inverse correlation was found between disease severity and the blastogenic response to pokeweed mitogen and herpes, parainfluenza, and measles antigens. These findings indicate that the decreased cell-mediated immune response in some MS patients is not specific for any of the viruses tested, and is probably a nonspecific effect of chronic disease. Patients with the relapsing-remitting form of the disease had a higher response to measles antigen and a lower response to pokeweed mitogen than patients with the chronic progressive form of the disease, suggesting that these variants differ immunologically as well as clinically.

Adult↗
PubMed1978

The effects of single-dose alternate-day prednisone therapy on the immunological status of patients with neuromuscular diseases.

Several immunological variables were examined in patients receiving high-single-dose, alternate-day prednisone therapy for neuromuscular diseases. Dose-dependent leukocytosis, lymphopenia, and monocytopenia occurred which were maximal 6 hours after prednisone administration but returned to control levels by the 24-hour point. The lymphopenia involved T-cells, B-cells, and null cells, with the T-cells most affected. Plasma cortisol levels and lymphocyte transformation in response to mitogens were also transiently and reversibly suppressed. There was a persistent decrease in serum IgG. Lymphocyte transformation was also suppressed when normal lymphocytes were incubated with treated patient sera or when treated patient lymphocytes were incubated in autologous pretreatment sera. The suppression factor was not removed from the lymphocytes by extensive washing. Patients whose disease responded to the high-single-dose, alternate-day prednisone regiment were indistinguishable from nonresponders by the immunological responses measured.

Adolescent↗
PubMed1978

Estimation of available dietary iron.

Dietary iron requirements are dependent on the amount and availability of food iron ingested. On the basis of recent studies of food iron absorption employing extrinsic tag techniques, the availability of heme iron has been defined and estimates of the availability of nonheme iron based on the amounts of enhancing substances appear possible. A model has been developed whereby the availability of iron in a given meal may be estimated. Calculations are made on a meal basis of 1) the amount of heme iron and its availability, and 2) the amount of nonheme iron and its availability as influenced by the meal's content of enhancing factors. Examples of these calculations are provided.

Absorption↗
PubMed1978

Influence of food iron absorption on the plasma iron level in idiopathic hemochromatosis.

The relationship between food iron absorption, iron stores, and plasma iron level was studied. On a low iron diet subjects with idiopathic hemochromatosis (IH) during reaccumulation of iron after phlebotomies showed a fall in plasma iron. Fortification of the diet with 22--135 mg of iron/day for 3 days caused little or no change in the plasma iron in subjects with normal iron stores, whereas in subjects with iron deficiency a significant rise in plasma iron occurred with the addition of 45 mg of iron/day. In subjects with IH with normal iron stores, plasma iron increased with the addition of 22.5 mg/day. These studies indicate that iron absorption is an important determinant of the elevated plasma iron in IH and that the plasma iron tolerance test combined with the serum ferritin may be used to detect excessive absorption of iron.

Bloodletting↗
PubMed1978

Iron transport by isolated rat intestinal mucosal cells.

In vitro uptake of radioiron by suspensions of isolated rat duodenal mucosal cells has been examined. The cells bind iron avidly, with uptakes of 15 to 20% after 20 min of incubation. Uptake is dependent upon temperature, pH, and iron and cell concentration. It is unaffected by inhibitors of cellular respiration but is blocked in a concentration-dependent fashion by iron-chelating agents. Iron-deficient cells take up iron at the same rate as normal cells. Binding by brush borders appears to account for 50 to 60% of the total uptake by isolated cells. In vitro radioiron uptake by isolated cells occurs by passive diffusion, is not regulated by the animal's iron status, and is primarily a function of bioavailability of iron in the incubating medium. If the model reflects the behavior of cells in vivo, the initial uptake of iron by the mucosa is a passive process which may serve to concentrate dilute luminal iron at the mucosal surface in preparation for absorption.

Animals↗
PubMed1977

Vitamin C, the common cold, and iron absorption.

A sizable segment of the population was found to be taking large quantities of vitamin C to reduce the number or severity of upper respiratory infections. To determine the affect of this supplementation on iron balance, multiple radioiron absorption tests were performed in 63 male subjects. The increase in iron absorption from a semisynthetic meal was directly proportional to the amount of ascorbic acid added over a range of 25 to 1,000 mg. The ratio of iron absorption with/without ascorbic acid at these two extremes was 1.65 and 9.57, respectively. The relative increase was substantially less when the test meal contained meat. A large dose of vitamin C taken with breakfast did not effect iron absorption from the noon or evening meal. A telephone survey of 100 individuals revealed that 67 were taking supplemental ascorbic acid in doses ranging as high as 2 g daily. The average intake of supplemental ascrobic acid in this population was 280 mg daily. If taken only with breakfast, this level of supplementation would produce a nearly 2-fold increase in the amount of iron absorbed daily. If taken in divided doses with each mean, the increase in iron absorption would be more than 3-fold.

Adolescent↗
PubMed1977

Morphologic and immunologic studies in experimental autoimmune myasthenia gravis and myasthenia gravis.

An indirect immunoperoxidase technique was used to study by light microscopy the binding of serum from experimental autoimmune myasthenia gravis (EAMG) rabbits to junctionally and extrajunctionally located acetylcholine receptors (AChRs) in human and rat muscles. Binding was restricted to junctional AChR. Alpha bungarotoxin (a-BGT) partially blocked the binding of EAMG serum, while myasthenia gravis serum, carbamylcholine, decamethonium, and tubocurarine did not. A radioimmunoassay showed significant binding of antibodies in EAMG sera to 125l AChR. This binding was not inhibited by a-BGT, nor by carbamylcholine, decamethonium, or tubocurarine. Sera from 10 myasthenia gravis patients did not contain antibodies binding to the 125l AChR. We suggest that EAMG in rabbits induced by Torpedo AChR differs serologically from myasthenia gravis in patients, probably owing to antigenic differences between Torpedo and human AChR, and that antigenic differences also exist between junctional and extrajunctional receptors.

Acetylcholine↗
PubMed1977

Iron balance in hemodialysis patients.

Iron deficiency is a frequent complication in chronically hemodialyzed patients because of the significant blood losses associated with this technique. Quantitating iron stores (by marrow examination or serum iron and total iron-binding capacity) on a repetitive basis had been difficult or unreliable, often resulting in failure to recognize iron deficiency superimposed on the existing anemia of chronic renal failure, or overtreating, which can lead to iron excess. Use of the serum ferritin allows easier quantitation of iron stores and, when measured serially in dialysis patients, can predict the emergence of iron deficiency. There was no correlation between serum ferritin levels and serum iron, total iron-binding capacity, or percent transferrin saturation. Iron absorption studies show that food iron absorption is physiologic, increasing when the serum ferritin is below 30 ng/ml, decreasing when more than 300 ng/ml. Treatment of iron deficiency with oral iron compounds increases serum ferritin levels and usually can maintain iron balance.

Ferritins↗
PubMed1977

Calcium metabolism in amyotrophic lateral sclerosis.

Calcium metabolism was studied prospectively in 12 patients with amyotrophic lateral sclerosis. Two patients showed mild hypocalcemia, malabsorption of calcium, and elevated plasma parathyroid hormone concentrations. Serum 25-hydroxyvitamin D was decreased in one and low-normal in the second. These two patients and a third showed aminoaciduria on thin layer chromatography. Calcium metabolism was apparently restored to normal by dihydrotachysterol, a vitamin D analog, but no improvement in neurologic function resulted. Bone radiographs taken in search of metabolic bone disease showed a significant increase in the incidence of congenital vertebral anomalies in the ALS patients (50% versus 8%). The relationship of the abnormalities in calcium metabolism and in vertebral structure to the etiology of motor neuron disease is not known.

Adult↗