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Biomedical subjects

I Knight

Publications and source records attributed to I Knight.

15 recordsLinked to original sources
PubMed2004

Beverage caffeine intake in US consumers and subpopulations of interest: estimates from the Share of Intake Panel survey.

Concerns exist about the potential adverse health effects of high consumption of dietary caffeine, especially in children and pregnant women. Recommended caffeine intakes corresponding to no adverse health effects have been suggested recently for healthy adults (400-450 mg/day), for women contemplating pregnancy (300 mg/day), and for young children age 4-6 years (45 mg/day). To determine whether current caffeine intake approaches these levels, intake from major dietary sources (coffee, tea and carbonated soft drinks) were measured in 10,712 caffeinated beverage consumers in the 1999 US Share of Intake Panel, a targeted beverage survey. Mean caffeine intakes in adult caffeinated beverage consumers ranged from 106 to 170 mg/day (90th percentile intake was 227-382 mg/day). In children 1-5 and 6-9 years, mean caffeine intakes were 14 and 22 mg/day, respectively; corresponding 90th percentile intakes were 37 and 45 mg/day. Pregnant women consumed an average of 58 mg/day (157 mg/day at the 90th percentile), and women of reproductive age ingested 91-109 mg/day (229-247 mg/day at the 90th percentile). These data show that while mean caffeine intakes are within recommended safe levels, heavy consumers of certain subpopulations, including young children and women contemplating pregnancy, might benefit from dietary advice.

Adolescent↗
PubMed2000

Detection of Bordetella pertussis in a clinical laboratory by culture, polymerase chain reaction, and direct fluorescent antibody staining; accuracy, and cost.

Control of Bordetella pertussis in the community is hampered by slow and insensitive diagnostic tests. We therefore examined the accuracy and cost of culture, direct fluorescent antibody (DFA) staining, and PCR in a routine clinical laboratory. Six hundred thirty seven nasopharyngeal swabs and aspirates in casamino acids transport medium were cultured, stained with polyclonal (Difco), and monoclonal (BL-5 and Accu-Mab) anti-B. pertussis reagents, and amplified by an IS481-specific PCR. PCR products were detected by a hybridization-enzyme immunoassay kit (Gen-eti-k DEIA, DiaSorin), with confirmation by a second PCR in a separate laboratory. Sensitivities and specificities of culture, polyclonal DFA, monoclonal DFA, and PCR were 36 and 100%, 11.4 and 94.6%, 8.3 and 98. 4%, and 95.0 and 99.3%, respectively, with a prevalence of 15.7%. The DFA tests were the most economical, and the PCR cost was 31% higher than culture. This study suggests that with minor improvements in economy, pertussis PCR can be implemented in a clinical laboratory with marked improvement in diagnostic accuracy.

Bordetella pertussis↗
PubMed1994

The development and applications of sucralose, a new high-intensity sweetener.

Sucralose is a new sweetener discovered during a collaborative research program between Tate & Lyle and Queen Elizabeth College of the University of London. It is made by selective substitution of sucrose hydroxyl groups by chlorine, resulting in a highly intense (600x) sugarlike sweetness and exceptional stability at both high temperature and low pH. The research leading to the discovery of sweetness in differently halogenated sucrose is described, as well as the development of sucralose and the process of safety testing and government approval. Finally, sucralose properties and applications in Canada's food and beverage industries are discussed.

Animals↗
PubMed1989

Mixed lymphocyte cultures using automated blood cell counters.

We compared the standard mixed lymphocyte culture technique with a new technique based on cell count and size distribution in a series of histocompatibility tests on 24 patients and 39 potential donors for bone marrow transplantation. We found that suspensions in which lymphocytes were undergoing transformation could be distinguished from those in which they were not after a 10-day incubation period by measuring the leucocyte count and size distribution in a Coulter S+ IV automated counter. The leucocyte count was higher and the size distribution was wider in suspensions where the lymphocytes were transforming. The correlation between relative response indices calculated using tritiated thymidine uptake or total nuclear mass was close (r = 0.7; p less than 0.001) although there were major differences in the response as assessed by each of the two techniques in some individual cases. We feel this method is suitable to screen large numbers of unrelated donors.

Anemia, Aplastic↗
PubMed1985

Fibrinogen Manchester. Detection of a heterozygous phenotype in the intraplatelet pool.

Family members heterozygous for the congenitally abnormal fibrinogen designated fibrinogen Manchester, A alpha 16Arg----His, have previously been shown by h.p.l.c. and amino acid analysis to release a variant fibrinopeptide, [His16]fibrinopeptide A, from plasma fibrinogen after the addition of thrombin. The present study was designed to determine if the same abnormal phenotype was also present in the intraplatelet fibrinogen pool. Fresh platelets were washed in buffers containing EDTA until it could be shown that all washable plasma fibrinogen was removed. Normal platelets were then lysed by freezing and thawing to release their intracellular proteins, which were then treated with thrombin. The fibrinopeptides, cleaved from the intraplatelet fibrinogen, could be detected by an optimized h.p.l.c. technique. Quantification of the intraplatelet fibrinogen gave a result (means +/- S.D., n = 5) of 110 +/- 30 and 90 +/- 30 micrograms/10(9) platelets, when determined by h.p.l.c. quantification of fibrinopeptide B content and fibrinogen fragment E radioimmunoassay respectively. Examination of fibrinopeptides released from the platelet fibrinogen from the family with fibrinogen Manchester with the same techniques showed elution peaks in the same positions as both [His16]fibrinopeptide A and normal fibrinopeptide A. The identity of these peaks was further substantiated by analysis of the h.p.l.c. peaks by using specific radioimmunoassay to fibrinopeptide A. Our results therefore demonstrate that platelet fibrinogen expresses the heterozygous A alpha 16His phenotype. This supports the view that the A alpha chains of platelet and plasma fibrinogen are produced from a single genetic locus.

Blood Platelets↗
PubMed1985

Relation of free silicone to human breast carcinoma.

Of 12 women with carcinoma of the breast and coexistent silicone mastopathy, nine had had injections of liquid silicone for breast augmentation; three had leaking silicone-gel prostheses. The clinical findings indicated that early diagnosis was obscured by the silicone-induced mastopathy, which rendered the interpretation of physical findings and mammograms difficult. The pathologic findings were suggestive of a possible adverse effect of the presence of free silicone within the breast tissue, axillary nodes, and axillary fat. Although no causal relationship between silicone and breast carcinoma is implied, a heightened awareness of the possible coexistence of silicone mastopathy and breast carcinoma is necessary.

Adult↗
PubMed1984

The significance of fibrinogen derivatives in plasma in human renal failure.

The concentrations in plasma of fibrinogen derivatives fibrinopeptide A (FPA), beta 15-42 antigen and fragment E (FgE) antigen have been determined in patients with renal failure and compared to the concentrations of the platelet release products, beta-thromboglobulin (beta TG) and platelet factor 4 (PF4). In 'partial renal failure' (51Cr-EDTA clearance rate 4-60 ml/min) FPA, beta 15-42 antigen, FgE antigen and beta TG levels were significantly raised above a normal laboratory control group. These levels were further raised in a group of patients whose disease required regular maintenance haemodialysis (51Cr-EDTA clearance rate less than 4 ml/min). PF4 levels were not significantly raised in either group. A statistical analysis of all patient results revealed that FPA, beta 15-42 antigen and FgE antigen levels all correlated with beta TG levels but not with PF4 levels. It is known that beta TG is catabolized by the kidney but PF4 is not and that elevated beta TG levels in renal failure are caused by impaired elimination rather than increased production. These results suggest that the plasma levels of these three fibrinogen derivatives are elevated in renal disease at least in part by decreased elimination rather than by increased thrombin and plasmin activities alone.

Adolescent↗
PubMed1982

Proteolysis of fibrinogen in healthy volunteers following major and minor vivo plasminogen activation.

Changes in immunoreactive fibrinopeptide A, fragment B beta 1-42 and fragment E were followed after major and minor in vivo plasminogen activation, after infusion of streptokinase and acylated streptokinase-plasminogen complex respectively, in healthy male volunteers. Major activation resulted in a dramatic rise in all three peptides, fragment E persisting in the circulation longest. Fragment B beta 1-42 was also markedly increased after minor systemic plasminogen activation despite apparently adequate levels of immediate antiplasmin.

Anistreplase↗