Incidence of exercise induced hypoxemia in elite endurance athletes at sea level

Recent evidence suggests that exercise-induced hypoxemia (EIH) may occur in healthy trained endurance athletes. However, at present, no data exist to describe the regularity of EIH in athletes or non-athletes. Therefore, the purpose of the present investigation was to determine the incidence of EIH during exercise in healthy subjects varying in physical fitness. Subjects (N = 68) performed an incremental cycle ergometer test to volitional fatigue with percent arterial oxyhemoglobin saturation (%SaO2) measured min-by-min. For the purpose of data analysis subjects were divided into three groups according to their level of physical training: 1) untrained (N = 16), 2) moderately trained (N = 27), and 3) elite highly trained endurance athletes (N = 25). EIH was defined as a %SaO2 of less than or equal to 91% during exercise. EIH did not occur in any of the untrained subjects or the moderately trained subjects. However, EIH occurred in 52% of the highly trained endurance athletes tested and was highly reproducible (r = 0.95; P less than 0.05). These findings further confirm the existence of EIH in healthy highly trained endurance athletes and suggests a rather high incidence of EIH in this healthy population. Hence, it is important that the clinician or physiologist performing exercise testing in elite endurance athletes recognize that EIH can and does occur in the elite endurance athlete in the absence of lung disease.

Accuracy of pulse oximetry to estimate HbO2 fraction of total Hb during exercise

The accuracy of two pulse oximeters (Ohmeda 3700 and Biox IIa) was evaluated during cycle ergometer incremental exercise in 10 healthy subjects. The exercise protocol began at 30 W with the power output being increased 15 W.min-1 until volitional fatigue. Ear and finger probe pulse oximetry measurements of available hemoglobin (%Spo2) were compared with arterial oxyhemoglobin fraction of total hemoglobin (%HbO2) measured directly from arterial blood samples using a CO-oximeter. To provide a wide range of %HbO2 values, four subjects exercised under hypoxic conditions [inspired partial pressure of O2 (PIo2) = 107 Torr], while the remaining six subjects exercised under normoxic conditions (PIo2 = 150 Torr). Because carboxyhemoglobin (HbCO) or methemoglobin (MetHb) is not measured by pulse oximeters, %HbO2 was corrected for HbCO and MetHb and expressed as percent arterial O2 saturation of available Hb (%Sao2). Small and insignificant differences (P greater than 0.05) existed between SpO2 (all 3 instruments) and %SaO2 at the lowest work rate and the highest power output achieved. Regression analyses of %SpO2 vs. %SaO2 produced correlation coefficients of r = 0.82 [standard error of the estimate [(SEE) = 1.79], r = 0.89 (SEE = 1.48), and r = 0.93 (SEE = 1.14) for the Biox IIa, Ohmeda 3700 (ear), and the Ohmeda 3700 (finger) pulse oximeters, respectively. We conclude that pulse oximetry, within the above limits of accuracy, is useful in estimating %SaO2 during exercise in healthy subjects.

Clinical predictors of computed tomographic abnormalities following pediatric traumatic brain injury

Children commonly seek attention in emergency departments following head injury. Head computed tomography (CT) is often used to decide subsequent disposition. Clinical criteria predicting CT abnormalities would allow effective and timely treatment and minimize unnecessary procedures depleting overburdened medical resources. We prospectively compared presenting clinical features with subsequent emergent head CT in 300 children less than 19 years old over a nine-month period. The disposition of patients following imaging was also recorded. Only suspected abuse was more than 50% positively predictive in children below age two and those above age two. Two signs were more than 67% positively predictive in both age groups: focal motor deficit and pupillary asymmetry. Patients with abnormal CTs were the only children to undergo emergent neurosurgery (30%) and were nearly five times as likely to be intensively monitored. Children with normal CTs were nearly five times as likely to be observed in a routine department or at home. We conclude that no single clinical feature can predict with certainty an abnormality on immediate head CT. However, children suspected of being abused, and those with focal motor deficits or pupillary asymmetry, should be imaged. Finally, emergent CT when judiciously ordered likely reduces unforeseen morbidity and minimizes costly intensive care observation.

Factors affecting adherence of end-stage renal disease patients to an exercise programme

Recently it has been shown that regular exercise is both physiologically and psychologically beneficial to patients with end-stage renal disease (ESRD). However, ESRD patients traditionally have a high non-adherence level to their self-care and medical regimens. To date, their adherence to exercise programmes has not been studied. Background information about employment, medical history, previous exercise habits and locus of control was obtained from 40 volunteer ESRD patients who started exercise at home. Twenty-eight participants maintained the exercise programme, consisting of aerobic activity lasting an average of 25 min, four times per week, for 12 weeks. The adherent patients were found to have encouraging support groups (75 versus 25%), to be between 41 and 60 years of age (64 versus 33%), to have been on dialysis for between 2 and 5 years, and to have loci of control (feeling of control over life events) classed as 'internal' (68 versus 25%). Factors such as sex, race, employment status and depression were found to have little influence on adherence. The major finding of this study was that patients adherent to exercise could be distinguished by unique psychological and psychosocial factors, and that adherence in this population was higher (70 compared with 50%) than some estimates for the general population.

Bioluminescent bioreporter integrated-circuit sensing of microbial volatile organic compounds

A bioluminescent bioreporter for the detection of the microbial volatile organic compound p-cymene was constructed as a model sensor for the detection of metabolic by-products indicative of microbial growth. The bioreporter, designated Pseudomonas putida UT93, contains a Vibrio fischeri luxCDABE gene fused to a p-cymene/p-cumate-inducible promoter derived from the P. putida F1 cym operon. Exposure of strain UT93 to 0.02-850 ppm p-cymene produced self-generated bioluminescence in less than 1.5 h. Signals in response to specific volatile organic compounds (VOCs) such as m- and p-xylene and styrene, also occurred, but at two-fold lower bioluminescent levels. The bioreporter was interfaced with an integrated-circuit microluminometer to create a miniaturized hybrid sensor for remote monitoring of p-cymene signatures. This bioluminescent bioreporter integrated-circuit device was capable of detecting fungal presence within approximately 3.5 h of initial exposure to a culture of p-cymene-producing Penicillium roqueforti.

Urinary ammonia plus urinary urea nitrogen as an estimate of total urinary nitrogen in patients receiving parenteral nutrition support

Nitrogen balance has historically been estimated by using urinary urea nitrogen (UUN) multiplied by a factor of 1.25 to account for nonurea nitrogen present in the urine. Recently, the reliability of UUN as an estimate of nitrogen losses has been questioned and the use of total urinary nitrogen (TUN) has been proposed as a more accurate measure of urinary nitrogen losses. However, analysis of TUN losses is not readily available in many hospital laboratories. Because ammonia is the major fluctuating component of urinary nonurea nitrogen and equipment to measure urinary ammonia is available in most hospitals, this study was undertaken to determine whether urinary ammonia plus UUN provides a clinically useful approximation of TUN. Twenty-four-hour urine samples acidified with boric acid during collection from 20 patients (a total of 42 samples) receiving total parenteral nutrition were analyzed for UUN, ammonia, and TUN. The UUN values ranged from 4.9 to 42.4 g/24 h. The mean difference between TUN and UUN was 1.99 +/- 0.27 g/24 h. The mean difference between TUN and UUN plus ammonia was 0.78 +/- 0.27 g/24 h. Thus, UUN alone accounted for 90% and the combination of UUN plus urinary ammonia accounted for 96% of TUN. These data suggest that UUN plus ammonia does provide a greater level of reliability as an estimate of TUN than UUN alone.

Effects of self-monitored exercise on selected blood chemistry parameters of end-stage renal disease patients

The effects of exercise on patients with end-stage renal disease (ESRD) is relatively unexplored. Of the complications associated with kidney failure, anemia and abnormal blood lipids profiles are among those that exercise may alter. Thus, the purpose of this study was to determine the effects of a self-monitored exercise program on the blood chemistry status in ESRD patients. The program consisted of aerobic activity maintained for a minimum of 15 min at least three times per week at an intensity of 10.8 +/- 2.13 on the Borg rating of perceived exertion scale (this scale correlates with heart rate and is used in cases where heart rate is not a reliable predictor of exercise intensity such as hemodialysis patients). Monthly blood samples were taken to assess the patients status regarding anemia and blood lipids. Results indicate no significant differences (P greater than 0.05) were seen from the beginning of the program until the end of the eighth month as seen below: [table; see text] Values are X +/- SEM. These data indicate that a self-monitored exercise program of moderate intensity may not be beneficial in helping regulate the anemia and altered blood lipid status of ESRD patients. Thus, since no physiological benefits are apparent with a self-monitored exercise program of low intensity, it is important to realize the potential risk involved with patients undertaking an unsupervised exercise program. These data illustrate that ESRD patients need supervised exercise programs in order to elicit a physiological training response.

HLA class II-like antiidiotypic antibodies from highly sensitized patients inhibit T-cell alloresponses

The purpose of this study is to identify factors in the sera of highly sensitized (HS) patients (pts) that inhibit T-cell alloresponses. An in vitro assay was used to measure HLA class I and class II-like antiidiotypic antibodies (anti-ids). The stimulation index (SI) was used to measure PBL and T-cell responses to alloantigens. All HS sera (32 pts) and the IgG fraction inhibited PBL and CD4(+) T-cell responses to alloantigens. The SI with HS IgG was 7.9 +/- 1.7 as compared to 31.5 +/- 5.9 with normal IgG (p = 0.0003). In a subset of pts who were transiently sensitized, the SI was 6.6 +/- 1.0 with a high panel reactive antibody (PRA), but when their PRA was zero, the SI was 17.8 +/- 1.3 (p = 0.0000001). Anti-ids were found in 100% of 17 pts with a high PRA. The T-cell inhibitory factors reduced CD4(+) T-cell responses of HS pts to alloantigens in the presence of autologous anti-ids, were MHC restricted and were inactivated by in vitro generated antibodies to HLA class II-like anti-ids. The HLA class II-like anti-id IgG molecules bind to the TCR of CD4(+) T cells and may impair their ability to help in the downregulating antibody response to anti-ids.

Anaphylaxis during intrauterine insemination secondary to bovine serum albumin

A case of anaphylaxis is reported after IUI with sperm processed in Tyrode's solution supplemented with BSA. The patient had a positive prick cutaneous test to BSA and also had specific IgE antibody against it. Repeat IUI using the patient's own blood serum instead of BSA for processing the sperm proceeded without incident. Clinicians should be aware of this rare, but not inconsequential, adverse effect of using xenogeneic proteins during IUI and other assisted reproductive techniques.

Evolution of interspersed repetitive elements inGossypium (Malvaceae)

Very little is known regarding how repetitive elements evolve inpolyploid organisms. Here we address this subject by fluorescent insitu hybridization (FISH) of 20 interspersed repetitive elements tometaphase chromosomes of the cotton AD-genome tetraploid Gossypiumhirsutum and its putative A- and D-genome diploid ancestors. Theseelements collectively represent an estimated 18% of the G.hirsutum genome, and constitute the majority of high-copyinterspersed repetitive elements in G. hirsutum. Seventeen ofthe elements yielded FISH signals on chromosomes of both G.hirsutum subgenomes, while three were A-subgenome specific. Hybridization of eight selected elements, two of which were A-subgenomespecific, to the A(2) genome of G. arboreum yielded asignal distribution that was similar to that of the G. hirsutumA-subgenome. However, when hybridized to the D(5) genome ofG. raimondii, the putative diploid ancestor of the G.hirsutum D-subgenome, none of the probes, including elements thatstrongly hybridized to both G. hirsutum subgenomes, yieldeddetectable signal. The results suggest that the majority, although notall, G. hirsutum interspersed repetitive elements haveundergone intergenomic concerted evolution following polyploidizationand that this has involved colonization of the D-subgenome byA-subgenome elements and/or replacement of D-subgenome elements byelements of the A-subgenometype.

Is your agency in a box?

As discussions and focus turn more and more to "systems thinking" and community integration, it is essential for a home health agency to see itself as an integral component of a seamless health care system. The agency must collaborate and cooperate with other members of the system and understand that while home care is an important part of the system, it is only one of the many pieces in a cooperative health care system.