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Biomedical subjects

J F Day

Publications and source records attributed to J F Day.

48 records · Page 3Linked to original sources
PubMed1983

Malaria renders mice susceptible to mosquito feeding when gametocytes are most infective.

Mice infected with Plasmodium berghei, P. chabaudi, or P. yoelii became lethargic and ceased to display normal antimosquito behavior. Periods of reduced defensiveness corresponded with maximum mosquito engorgement and with periods of maximum gametocyte infectivity to mosquitoes. Increased feeding success of mosquitoes during periods of peak gametocyte infectivity may be important to the natural maintenance of these malaria parasites.

Aedes↗
PubMed1983

Longterm effects of cyclophosphamide on granulocyte colony formation in patients with rheumatoid arthritis.

Longterm cytotoxic therapy, particularly with alkylating agents, is frequently associated with the development of second neoplasms, particularly acute myeloid leukemia. Twelve patients with classic, progressive rheumatoid arthritis (RA), treated with a cytotoxic agent, cyclophosphamide, from 1969 to 1974 at the University of Colorado Health Sciences Center were reassessed for current status of the granulocytic system. Bone marrow biopsies were investigated histologically and the number of granulocyte precursor cells judged using colony forming cells in culture (CFU-C). Control bone marrow biopsies were done on 8 patients with classic, progressive RA who had not taken cyclophosphamide as well as 16 healthy controls. Colony forming cell numbers in patients with RA who had been treated with cyclophosphamide were significantly lower compared to patients with RA who had not received cyclophosphamide and normal controls. These data suggest that cyclophosphamide may cause suppression of the hematopoietic system that does not totally recover even after long periods of time.

Aged↗
PubMed1980

Carbohydrate-mediated clearance of immune complexes from the circulation. A role for galactose residues in the hepatic uptake of IgG-antigen complexes.

The purpose of these experiments was to evaluate the hypothesis that galactose residues on IgG mediate the clearance of IgG.antigen complexes from the circulation. After 28 days of immunization of rats with bovine serum albumin (BSA), approximately 90% of anti-BSA antibody was IgG; the circulating half-life of trace amounts of BSA antigen in immunized rats was 6 min, compared to 24 h in nonimmunized rats. Similarly, soluble IgG.125I-BSA complexes formed in vitro, under conditions of antibody excess, had a circulating half-life of 4 min in normal rats. For both antigen in immunized rats, or IgG.125I-BSA complexes in normal animals, clearance was markedly inhibited by pre- or co-injection of asialofetuin, but was insensitive to large doses of fetuin, ovalbumin, or mannan. Liver parenchymal cells were the major site of uptake of complexes formed in vivo or in vitro. In vitro binding of IgG.125I-BSA complexes by isolated hepatocytes was effectively competed by asialofetuin, asialo-orosomucoid, galactose, and N-acetylgalactosamine, but was unaffected by fetuin, orosomucoid, ovalbumin, mannan, or mannose. These data suggest that antigen-induced conformational changes in IgG result in both recognition of galactose residues on IgG and clearance of IgG-immune complexes from the circulation by the galactose-specific receptor in hepatic parenchymal cells.

Animals↗
PubMed1980

Carbohydrate-mediated clearance of antibody . antigen complexes from the circulation. The role of high mannose oligosaccharides in the hepatic uptake of IgM . antigen complexes.

After immunization of rats with bovine serum albumin (BSA) for a 12-day period, approximately 90% of anti-BSA antibody was IgM. The circulating half-life of limiting amounts of 125I-BSA in immunized and control rats was 6 min and 24 h, respectively. The rapid clearance of 125I-BSA was inhibited by pre- or co-injection of mannan and ovalbumin, but not by asialofetuin, rat serum albumin, carbon particles, dextran, or depletion of serum complement. Soluble IgM . 125I-BSA complexes, formed in vitro under conditions of antibody excess, were rapidly cleared from the circulation of nonimmunized rats, and clearance was also inhibited by ovalbumin but not by asialofetuin. Immune complexes formed in vivo or in vitro were recovered primarily (approximately 60% of dose) in hepatic nonparenchymal cells and in other organs of the reticuloendothelial system. In experiments in vitro, IgM was bound tightly by concanavalin A only when complexed with antigen. Digestion of IgM . 125I-BSA complexes with alpha-mannosidase abolished both binding by concanavalin A and rapid clearance in normal rats. These data suggest that antigen-induced conformational changes can result in exposure of high mannose oligosaccharides on IgM which signal the clearance of soluble immune complexes from the circulation.

Animals↗
PubMed1980

Nonenzymatic glucosylation of serum proteins and hemoglobin: response to changes in blood glucose levels in diabetic rats.

The relationship between concentrations of blood glucose and nonenzymatically glucosylated serum proteins was studied in rats with alloxan-induced diabetes of varying severity. Fasting serum glucose correlated strongly with both glucosylated albumin (r = 0.91, P less than 0.001) and glucosylated serum protein (r = 0.93, P less than 0.001). The relative rates of response of serum protein and hemoglobin glycosylation to changes in blood glucose were also compared. Following withdrawal of insulin from diabetic rats, the half-times to reach new steady state levels of blood glucose, glucosylated serum proteins, and glycohemoglobins were about 2, 3, and 8 days, respectively. Similarly, on reinstitution of insulin therapy, the half-times for these same indices to return to baseline values were 2, 3.5, and 15 days, respectively. Changes in glucosylated albumin were more sensitive than glycohemoglobins to changes in serum glucose, consistent with the observation that albumin was glucosylated at about 10 times the rate for hemoglobin in incubations in vitro. These data indicate that glucosylated serum protein measurements can serve as a sensitive, short-term integrator of blood glucose homeostasis in diabetes.

Animals↗
PubMed1979

Nonenzymatically glucosylated albumin. In vitro preparation and isolation from normal human serum.

Incubation of human serum with D-[6-3H]glucose resulted in the gradual accumulation of radioactivity in acid-precipitable material. Upon chromatography on Sephadex G-200, radioactivity was found associated with each of the major molecular weight classes of serum protein. Purified human serum albumin was also glucosylated in vitro upon exposure to D-[6-3H]glucose in phosphate-buffered saline. The glucosylated and unmodified albumins were separated by ion exchange chromatography. The physiological significance of these observations in vitro was confirmed by the isolation and quantitation of glucosylated albumin from normal human serum. Glucosylated albumin represents approximately 6 to 15% of total serum albumin in normal adults. The post-translational modification appears to occur by a nonenzymatic process analogous to that responsible for glucosylation of hemoglobin A to hemoglobin AIc, i.e. through Schiff base formation and Amadori rearrangement to a ketoamine derivative.

Blood Glucose↗
PubMed1979

Enhanced nonenzymatic glucosylation of human serum albumin in diabetes mellitus.

Use of an ion exchange chromatographic method and a colorimetric method with thiobarbituric acid showed that levels of nonenzymatically glucosylated serum albumin were increased in patients with poorly controlled diabetes mellitus compared to controls. The two methods correlated well (r = 0.99) and clearly discriminated between normal and poorly controlled diabetic populations. The levels of glycosylated hemoglobin were also measured in both populations. Several patients apparently in good control based on glycosylated hemoglobin measurements were found to have increased levels of glycosylated albumin. Because albumin has a shorter circulating half-life than does the human erythrocyte, the plasma concentration of glucosylated albumin should be expected to reflect short-term control of hyperglycemia in diabetes. The studies reported here suggest that the level of glucosylated albumin may indeed be a sensitive indicator of moderate hyperglycemia and of early glucose intolerance.

Blood Glucose↗
PubMed1979

Nonenzymatic glucosylation of serum proteins in diabetes mellitus.

The extent of nonenzymatic glucosylation of serum protein in control and diabetic subjects was measured by a chemical procedure using thiobarbituric acid. A mean value of 0.81 (+/- 0.21 SD) nmol glucose per milligram serum protein was observed in the control group. Diabetics displayed elevated levels of glucosylated serum proteins, up to 4 nmol glucose per milligram protein. Glucosylation of serum protein correlated strongly with fasting blood sugar (r = 0.71), percent hemoglobin A1 (r = 0.79), and percent glucosylated albumin (r = 0.99). There was no overlap between control and diabetic groups, i.e., within 3 SD of the mean of controls. These studies indicate that the assay for glucosylated serum protein appears to be an especially sensitive indicator of the degree of hyperglycemia in diabetes.

Blood Proteins↗