Measurement of Carboxyhemoglobin and Methemoglobin by Pulse Oximetry: A Human Volunteer Study

Background: A new eight-wavelength pulse oximeter is designed to measure methemoglobin and carboxyhemoglobin, in addition to the usual measurements of hemoglobin oxygen saturation and pulse rate. This study examines this device's ability to measure dyshemoglobins in human volunteers in whom controlled levels of methemoglobin and carboxyhemoglobin are induced.

Methods: Ten volunteers breathed 500 ppm carbon monoxide until their carboxyhemoglobin levels reached 15%, and 10 different volunteers received intravenous sodium nitrite, 300 mg, to induce methemoglobin. All were instrumented with arterial cannulas and six Masimo Rad-57 (Masimo Inc., Irvine, CA) pulse oximeter sensors. Arterial blood was analyzed by three laboratory CO-oximeters, and the resulting carboxyhemoglobin and methemoglobin measurements were compared with the corresponding pulse oximeter readings.

Results: The Rad-57 measured carboxyhemoglobin with an uncertainty of +/-2% within the range of 0-15%, and it measured methemoglobin with an uncertainty of 0.5% within the range of 0-12%.     

Athletic identity and its relationship to sport participation levels

This study looked at the relationship between athletic identity and three levels of sport participation (elite, recreational, non-participation). Athletic identity was measured using the Athletic Identity Measurement Scale (AIMS) with participants being compared on the total AIMS score and scores on its three factors (social identity, exclusivity, negative affectivity). Results indicated that the male non-participation group scored lower on all three factors and the total AIMS when compared to the two athlete groups. The male elite and recreational groups did not differ on exclusivity and negative affectivity but did differ on the total AIMS and social identity, with elite scoring higher than recreational. For female participants, the non-participation group again scored lower on all three factors and the total AIMS when compared to the two athlete groups. The female elite and recreational groups did not differ on negative affectivity but did differ on the total AIMS, social identity, and exclusivity, with elite scoring higher than recreational. Findings suggest that to assume sport is only important to elite athletes ignores the role that sport may play for less talented sport participants. Whilst not seeing themselves as athletes per se, it is suggested that participation in sport may still impact upon the self-perceptions of recreational sport participants. Therefore, threats to participation may result in similar negative consequences for both elite athletes and recreational sport participants.     

Transplantation of horseshoe kidneyinto single recipient

A case of successful en bloc transplantation of a horseshoe kidney into a single recipient is reported. The literature is briefly reviewed. The use of horseshoe kidneys in transplantation is recommended in selected cases.     

Apolipoprotein E—associated risk for Alzheimer's disease in the African-American population is genotype dependent

As a part of our ongoing study on Alzheimer's disease (AD) in elderly African Americans, we obtained clinical assessment and apolipoprotein E (ApoE) genotype data on 288 individuals (including 60 with AD). The ApoE σ4 allele frequency was significantly increased in AD patients compared with controls. The age-adjusted odds ratio (OR) for AD in σ4 homozygotes was 4.83 (95% confidence interval [CI], 1.71–13.64) compared with the σ3/σ3 genotype, but the OR for AD with the σ3/σ4 genotype did not reach significance (1.20; 95% CI, 0.58–2.45). These findings suggest that the association between ApoE σ4 and AD is weaker in African Americans than in whites.     

Exchangeable magnesium pool masses in healthy women: effects of magnesium supplementation.

BACKGROUND: Studying magnesium pools in the body with use of stable isotopes may be helpful for evaluating magnesium status. Data on the evaluation of magnesium pools in humans are scarce. OBJECTIVE: We undertook this study to evaluate the effects of a magnesium supplementation program on the size of the exchangeable body pools of magnesium and on classic indexes of magnesium status in healthy women with normal magnesium status. DESIGN: Ten healthy women participated in a kinetic study with magnesium stable isotopes before and after 8 wk of magnesium supplementation. Each woman received 3 supplements containing 5.08 mmol (122 mg) elemental Mg/d (366 mg/d). Before and at the end of the supplementation period, each woman received an intravenous injection of 1.67 mmol (40 mg) (25)Mg, and the plasma magnesium disappearance curve was followed for the next 7 d. Two methods were used to analyze the exchangeable pools of magnesium: 1) formal multicompartmental modeling and 2) a simplified estimation of the total mass of the rapidly exchangeable magnesium pool (EMgP). RESULTS: In these healthy women, exchangeable magnesium pools represented 11-12% of total body magnesium on the basis of multicompartmental analysis. The simplified estimation of EMgP overestimated the size of the exchangeable magnesium pools by approximately 45-50%. Eight weeks of magnesium supplementation did not significantly modify the size of the exchangeable magnesium pools, whereas urinary magnesium excretion was significantly higher after 8 wk of supplementation. CONCLUSION: Women with no clinical evidence of magnesium deficiency may not respond to short-term supplementation with increases in the mass of the exchangeable magnesium body pool or in magnesium turnover rates.     

Evidence for nitric oxide participation in down-regulation of CYP2B1/2 gene expression at the pretranslational level

Septic or inflammatory stimuli suppress drug metabolism by cytochrome P-450 in the liver, presumably at the pretranslational level. We have shown previously that nitric oxide is responsible at least in part for the inhibition by bacterial lipopolysaccharide of phenobarbital-induced CYP2B1/2 activity in vivo. This was attributed to the interaction of nitric oxide with heme in the active-center of cytochrome P450, leading to enzyme inactivation. Here, we report of nitric oxide with heme in the active-center of cytochrome P450, leading to enzyme inactivation. Here, we report that endogeneous nitric oxide also contributes to LPS-induced suppression of CYP2B1/2 in vivo by down-regulating the expression of CYP2B1/2 protein and mRNA.     

FEASIBILITY OF CONDUCTING CARDIOVASCULAR OUTCOME RESEARCH IN AUSTRALIAN GENERAL PRACTICE: RESULTS FROM THE ANBP2 PILOT STUDY

1. The present study aimed to determine the feasibility of conducting a 5 year cardiovascular outcome trial of the treatment of 6000 elderly hypertensive patients in Australian general practices. 2. General practitioners (GPs) were invited to participate by mail and personal follow-up. Patient records were reviewed to identify subjects for a blood pressure (BP) screening programme. Blood pressure was measured on three occasions and eligible subjects were included if the average BP was 160 mmHg systolic or 90 mmHg diastolic if systolic BP was 140 mmHg. 3. Seven hundred and forty-one GPs were approached and 89 were enrolled in the study (12% of mail invites and 75% of those receiving a personal contact). In 16 practices where screening was completed, 82 000 records were reviewed to identify 4% patients eligible for screening. Twenty-two per cent of eligible subjects attended screening. Of 1938 subjects screened, 180 (9%) had BP 5=160/90 mmHg. Forty-seven percent of subjects (n = 916) were receiving antihypertensive therapy and 184 (20%) were withdrawn from therapy. One hundred and sixteen (63%) of these subjects had BP return to study entry levels within 6 weeks. Fifty-seven newly diagnosed and 81 previously treated subjects were randomized (7% of the screened population). 4. Based on the high participation rate of GPs, the response rate of patients to attend a BP screening programme and the 7% randomization to screening ratio for entry into the study, the ANBP2 pilot study has demonstrated that it is feasible to recruit subjects from Australian general practices to a cardiovascular outcome trial.     

Transitional properties of the mechanically evoked perioral reflex from infancy through adulthood

The organization of motor responses in the orbicularis oris muscle following the delivery of punctate mechanical inputs to vermilion skin of the lips was studied in a group of young infants, school-age children, and adults during periods of voluntary lip muscle activation. A specially designed multi-point array skin contactor, coupled to a position-servo controlled linear motor, was highly effective in driving the early component of the perioral reflex (R1). Overall, the evoked R1 response obtained from the infant was of variable amplitude relative to the children and adults, lacked response specificity, and occurred it a longer latency. This brainstem mediated sensorimotor action appears to take on several characteristics of the adult form by the age of 12. The emergence and maturation of mechanically evoked perioral reflexes is discussed in relation to the acquisition of motor skills, including speech and smiling.