Biomedical subjects

E A Higgins

Publications and source records attributed to E A Higgins.

At least 19 recordsLinked to original sources

PubMed1992

Measurement of 226Ra and 228Ra in water by gamma-ray counting after preconcentration on ion-exchange resin.

A rugged resin concentration method followed by gamma counting was developed for measuring 226Ra and 228Ra in drinking water. Using typical distribution system pressure, 310 kPa (45 psig), radium in a 20-L sample was concentrated 100-fold onto 200 mL of ion-exchange resin beads that were then sealed in a glass jar for gamma activity measurement. Parameters and materials affecting the concentration step were studied with the objective of maximizing radium recovery in a short time. Empty bed contact times were varied from 0.1-3.0 min (2.0-0.67 mL min-1) and input concentrations of radium were varied from 370-3700 Bq m-3 (10-100 pCi L-1). Varying these parameters did not affect the percentage recovery of radium by the resin. At each empty bed contact time after all adsorbent media were tested, more than 99% of the influent radium was adsorbed. In these experiments, activities were counted for 100 min using a gamma-ray spectrometer equipped with a 3 x 3-inch sodium iodide (thalium-activated) [NaI(Tl)] crystal detector. Activity calculations were based on resin loaded with traceable standard solutions of 226Ra and 286Ra from the National Institute of Standards and Technology. Analyzing entire spectra with a least-squares analysis program resulted in limits of detection for 226Ra and 228Ra of 7.4 Bq m-3 (0.2 pCi L-1) and 33.3 Bq m-3 (0.9 pCi L-1), respectively.

Ion Exchange Resins↗

PubMed1991

Aberrant O-linked oligosaccharide biosynthesis in lymphocytes and platelets from patients with the Wiskott-Aldrich syndrome.

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive immunodeficiency affecting B lymphocytes, T lymphocytes, and platelets. Previous studies on lymphocytes from WAS patients have revealed that leu-kosialin (CD43), a cell-surface glycoprotein bearing approximately 90 O-linked oligosaccharide chains, shows an aberrant electrophoretic mobility. To determine whether this finding reflects a different pattern of O-linked glycosylation in WAS cells, we have compared healthy individuals and WAS patients with respect to glycosyltransferase activities in T lymphocytes, platelets, and Epstein-Barr virus (EBV)-immortalized B cell lines. Stimulation of peripheral T cells from normal individuals in vitro with anti-CD3 antibodies and interleukin-2 was associated with a 3-fold increase in UDP-GlcNAc:Gal beta 3GalNAc-R (GlcNAc to GalNAc) beta 6-N-acetylglucosaminyltransferase (core 2 GlcNAc-T) from 0.8 to 2.2 nmol/mg/h. In contrast, peripheral T lymphocytes from WAS patients showed an inversion of this phenotype with high core 2 GlcNAc-T activity in unstimulated cells (2.3 nmol/mg/h) and a 2-3-fold decrease in activity following stimulation. Core 2 GlcNAc-T activity was also three times higher in platelets from WAS patients than in normal platelets. Glycosyltransferase activities were measured in immortalized B cell lines established from WAS and normal subjects by infection with EBV. Core 2 GlcNAc-T was less than 0.4 nmol/mg/h in WAS EBV-B cell lines compared to 2.4 nmol/mg/h in EBV-B cell lines from healthy individuals, In contrast, CMP-SA:SA alpha 2-3Gal beta 1-3GalNAc-R (where SA represents sialyl (sialic acid to GalNAc) alpha 6-sialyltransferase II activity was 2.0 nmol/mg/h in the WAS EBV-B cell and less than .01 nmol/mg/h in EBV-B cell lines derived from normal subjects. Eleven other glycosyltransferase activities were measured and found to be similar in EBV-B cell lines from WAS and normal individuals. Polylactosamine sequences were much reduced in the O-linked oligosaccharides of CD43 from WAS EBV-B cells consistent with decreased core 2 GlcNAc-T activity and expression of core 1 oligosaccharides in the cells. In conclusion, B cells, T cells, and platelets in WAS patients show abnormal expression of two developmentally regulated glycosyltransferases, consistent with the idea that the WAS immunodeficiency is due to a failure of normal lymphocyte maturation.

Adolescent↗

PubMed1987

Some effects of alcohol and simulated altitude on complex performance scores and breathalyzer readings.

Each of 17 men was trained on 7 tasks in the Multiple Task Performance Battery and then performed over a 2-week period in four experimental sessions: ground level with and without alcohol, and simulated altitude (12,500 ft), with and without alcohol. Subjects breathed appropriate gas mixtures through oxygen masks at both ground level and altitude. Alcohol doses of 100-proof vodka mixed with juice 2.2 ml X kg-1 of body weight. Results showed no differential effect of simulated altitude on breathalyzer readings (peaks averaged 78 mg % at 12,500 ft and 77 mg % at ground level). The best performance occurred at ground level under placebo conditions; the 12,500-ft simulated altitude produced some decrement for placebo scores. Alcohol at ground level resulted in significantly impaired performance during the morning sessions; the addition of altitude to the alcohol condition further depressed performance scores, but to about the same extent that placebo scores were depressed by altitude. Thus, there was no synergistic interactive effect of alcohol and altitude on either breathalyzer readings or performance scores.

Adult↗

PubMed1982

Physiological biochemical, and performance responses to a 24-hour crash diet.

Twelve overweight male subjects were evaluated on both a normal diet and a 24-h crash diet. During approximately 2 1/4-h complex performance tests subjects breathed an O2/N2 mixture equivalent to 3810 m. (12,500 ft). There were no significant findings due to diet for heart rate, blood pressure, serum electrolytes, subjective fatigue and urinary excretion of K+, epinephrine and norepinephrine. body temperatures were lower (p less than 0.05) for the crash diet than for the normal diet. Serum glucose levels increased during the normal diet and decreased during the crash diet. Hematocrit increased more for the crash diet (p less than 0.05) than for the normal diet. Urinary excretion of 17-ketogenic steroids was less (p less than 0.001) during sleep for the crash diet than for the normal diet. Complex performance showed no significant differences when subjects were tested under low workloads. Performance was enhanced during the crash diet when subjects were tested under the medium and high workload conditions.

Adolescent↗

PubMed1979

Effects of altitude and two decongestant-antihistamine preparations on physiological functions and performance.

Fourteen men were studied to determine the combined effects of two altitudes--388 and 3,810 m or 1,274 and 12,500 ft--and three preparations--lactose placebo, Compound A (Actified, and Compound B (Dristan). Subjects reported least attentiveness with A and greatest with placebo. Fatigue increased significantly with time while energy, interest, and attentiveness decreased. The Multiple Task Performance Battery (MTPB) showed no effects of altitude, drugs, or time on overall performance; however, performance declined with time in several tasks, while problem solving improved. Subjects enjoyed the problem-solving tasks and may have given them preference as levels of interest declined. Though the MTPB overall composite scores did not change significantly, physiological parameters and subjective evaluations indicate that type of compound and time after ingestion are important. Declines in energy and attentiveness 2.5 h after ingestion could result in neglect of important--although routine--tasks. Hypoxia might enhance this effect and consequences might be worse in subjects whose medical conditions require these drugs.

17-Ketosteroids↗

PubMed1978

Biological aspects of suicide: circadian disorganization.

Disturbances in the circadian rhythmicity of biological functions have been reported in various mental disorders. Four lines of research--hormonal, electroencephalographic, cerebral spinal fluid, and circadian rhythmicity--suggest possible changes in suicidal individuals. During a study investigating the effect of a photoperiod shift on circadian rhythms, 15 male, healthy, normal subjects were used. Following a 5-day baseline period a 12-hour photoperiod shift took place and was followed by 10 days of recovery period. Multiple parameters were monitored. Two weeks following completion of the study one subject suicided. The data were examined to determine whether the suicided subject differed, rhythmically, from other subjects. Summation dials describing phase changes and vector difference dials describing dynamic phase relationships of rhythm pairs showed that the rhythms of this subject were poorly synchronized internally during baseline. Total urinary output of all parameters was lower than all other subjects during baseline and more of his urinary parameters rephased incompletely during recovery. The results suggest that circadian asynchrony and an inability to respond effectively to a phase shift may characterize a presuicidal state. These results are discussed in terms of the four lines of research involving biological aspects of suicide and suggest some intriguing interactions.

17-Hydroxycorticosteroids↗

PubMed1977

Transient and permanent effects of hyperthermia in dogs: a study of a simulated air transport environmental stress.

Heat-induced hyperthermia can be a major problem in dogs shipped during summer months. Dogs shipped by air transport can encounter temperatures as high as 54.4 C. Usually, little concern is given to effects produced by hyperthermia. To assess the heat stress problem, 20 dogs were exposed to a temperature of 54.4 C for 30 minutes--10 dogs at 15% relative humidity and 10 dogs at 35%. Dogs did not die as a result of exposure, but certain transient and permanent changes occurred. All dogs had increased heart rate, rectal temperature, blood pH, hemoglobin concentration, packed cell volume, and erythrocyte count. Body weight and PVCO2, decreased. Differences also were shown between the 2 humidity group for blood PH PVCO2, rectal temperature, and weight loss. The major tissue changes attributed to hyperthermia were fragmentation of the myocardium, acute cortical necrosis in kidney, and marked degenerative changes in the cerebellum and cerebral cortex. Changes in the cerebellum and cerebral cortex were considered severe and permanent.

Aircraft↗

PubMed1976

Effect of physical activity of airline flight attendants on their time of useful consciousness in a rapid decompression.

To determine the effect of physical activity on the "time of useful consciousness" (TUC) of airline flight attendants in a rapid, severe decompression, 10 male and 10 female subjects were exposed to a decompression profile while at rest and performing light-to-moderate work. Decompression from 6,500 to 34,000 ft (2,000 to 10,400 m) was followed by descent at 5,000 ft/min (1,500 m/min). The average TUC for the males decreased from 54 s (omega 7.1) at rest to 34 s (omega 4.4) while performing work. The average TUC for the females decreased from 54 s (omega 8.1) at rest to 32 s (omega 4.0) while performing work. Supplemental oxygen had a marked paradoxical effect when the subjects were performing work.

Aerospace Medicine↗

PubMed1976

Protection of airline flight attendants from hypoxia following rapid decompression.

To determine the maximum time for working flight attendants to effectively initiate airline passenger mask donning after onset of a rapid, severe decompression, we exposed 10 subjects in two series of tests to a decompression from 6,500 to 34,000 ft (2,000 to 10,400 m) in 26 s, followed by descent at 5,000 ft/min (1,500 m/min) while subjects performed a light-to-moderate workload. Supplemental oxygen was provided in one series from a compressed oxygen system, and in the other series from a chemical oxygen generator system. With delays to mask doning of 10 and 15 s, no hypoxic effects occurred. With delays of 20 and 25 s, increasing hypoxic effects, similar in frequency for the two systems, occurred. Some technical problems in mask donning contributed to losses of consciousness with the latter two delays.

Adult↗

PubMed1972