Accurate heart rate measurement during work is required for many industrial hygiene and ergonomics situations. The purpose of this investigation was to determine the validity of heart rate measurements obtained by a simple, lightweight, commercially available wrist-worn heart rate monitor (HRM) during work (cycle exercise) sessions conducted in the laboratory and also during the particularly challenging work environment of space flight. Three different comparisons were made. The first compared HRM data to simultaneous electrocardiogram (ECG) recordings of varying heart rates that were generated by an ECG simulator. The second compared HRM data to ECG recordings collected during work sessions of 14 subjects in the laboratory. Finally, ECG downlink and HRM data were compared in four astronauts who performed cycle exercise during space flight. The data were analyzed using regression techniques. The results were that the HRM recorded virtually identical heart rates compared with ECG recordings for the data set generated by an ECG simulator. The regression equation for the relationship between ECG versus HRM heart rate data during work in the laboratory was: ECG HR = 0.99 x (HRM) + 0.82 (r2 = 0.99). Finally, the agreement between ECG downlink data and HRM data during space flight was also very high, with the regression equation being: Downlink ECG HR = 1.05 x (HRM) -5.71 (r2 = 0.99). The results of this study indicate that the HRM provides accurate data and may be used to reliably obtain valid data regarding heart rate responses during work.

Adult↗

PubMed1997

Impact of body size on women's military obstacle course performance.

The United States Military Academy uses an Indoor Obstacle Course Test (IOCT) to assess military-relevant physical fitness. There are both anaerobic and aerobic fitness components to this test. Recent attention has been focused on the apparent difficulty of heavier female cadets to succeed on the IOCT. The purpose of this study was to use allometric scaling to examine the effects of body weight (BW), fat-free mass (FFM), percent body fat (%BF), and fat mass (FM) on IOCT performance for female cadets. The sample included 38 female cadets who successfully completed the IOCT. Performance was defined by the time, T, to complete the entire course. FFM was determined via a three-site skinfold test. Allometric modeling was used to determine the exponent in the following index: T*BW2 such that the independent contributions of body size are partialled out. This analysis was used for all four independent variables simply by substituting BW with the other independent variables. The following exponents were found to be significant (p < 0.05): 0.45 +/- 0.13 for %BF and 0.24 +/- 0.12 for FM indicating that these independent variables play a significant role in female performance on the IOCT. For example, if a female cadet could decrease her %BF from 20% to 18%, which would be decrement of ten percent, then her estimated decrease in IOCT time is 4%. In addition, a trend (p = 0.06) was found for FFM meaning that as FFM increases, T decreases. We conclude that, among USMA female cadets, small decreases in %BF may be significantly advantageous to IOCT performance.

Adult↗

PubMed1996

Type VI collagen is present in human and bovine vitreous.

BACKGROUND: Heterotypic (mixed) collagen fibrils that contain collagen types II, IX and V/XI have previously been identified in vitreous gel. The purpose of this study was to determine whether vitreous gel also contains type VI collagen microfibrils, as they are widely distributed in other tissues where they may play an important structural role. METHODS: Bovine and human vitreous gel was analysed by rotary shadowing electron microscopy after bacterial collagenase digestion and gel filtration chromatography. Bovine vitreous was extracted in 4 M guanidine hydrochloride, and following isopycnic centrifugation fractions were analysed by western blotting. RESULTS: Type VI collagen microfibrils were identified by electron microscopy in human and bovine vitreous. Type VI collagen was identified by western blot analysis. CONCLUSION: Type VI collagen is present in vitreous and may participate in the structural assembly of the vitreous gel.

Animals↗

PubMed1996

An open phase I study to assess the biological effects of a continuous intravenous infusion of Interleukin-3 followed by Granulocyte Macrophage-Colony Stimulating Factor.

To assess any synergistic stimulatory effect in vivo of Interleukin 3 (IL-3) and Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) upon white cell and platelet counts, toxicity and antitumour effect, we conducted this phase I study. IL-3 0.25, 0.5 or 5 micrograms/kg/day for 1, 4 or 7 days was given by continuous intravenous (i.v.) infusion to 35 patients with advanced malignancy. 21 of the 35 patients also received sequential or overlapping treatment with continuous i.v. infusion of GM-CSF 1 or 3 micrograms/kg/day for up to 10 days. Monotherapy with IL-3 producted significant dose related increases in platelets and white cell counts. Combinations of IL-3 and GM-CSF also produced increases in white cell counts, but these were no greater than would be expected following GM-CSF treatment alone. There was a trend for platelets to increase more in patients receiving IL-3 and GM-CSF than those receiving IL-3 alone, but this did not reach statistical significance. In general, IL-3 and combinations of IL-3 and GM-CSF were well tolerated and the most common side-effect was fever. A maximum tolerated dose was not reached and antitumour effects were not seen. Future studies using combinations of IL-3 5 micrograms/kg/day and GM-CSF 3 micrograms/kg/day may help to define the optimal therapeutic regimen.

Adolescent↗

PubMed1996

The biochemical structure of mammalian vitreous.

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Age Factors↗

PubMed1996

High-level expression of recombinant human fibrinogen in the milk of transgenic mice.

Fibrinogen is a complex plasma protein composed of two each of three different polypeptide chains. We have targeted expression of r-human fibrinogen to the mammary gland of transgenic mice. Three expression cassettes, each containing the genomic sequence for one of the three human fibrinogen chains controlled by sheep whey protein beta-lactoglobulin promoter sequences, were coinjected into fertile mouse eggs. Southern blot analysis demonstrated that more than 80% of the transgenic founders contained all three fibrinogen genes. Reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis of milk from the highest producing founder animal demonstrated the presence of human fibrinogen subunits at concentrations of 2000 micrograms/ml. In several animals with a balanced ratio of the individual fibrinogen subunits, up to 100% of the protein was incorporated into fully assembled fibrinogen hexamers. Incubation of the transgenic milk with thrombin and factor XIII resulted in a cross-linked fibrin clot, indicating that a major portion of the secreted fibrinogen was functional. These studies represent the first report of high-level biosynthesis and secretion of a functional, complex, hexameric protein in the milk of a transgenic animal.

Animals↗

PubMed1996

Epstein-Barr virus associated graft failure following heart/lung transplantation.

A case is described of late pulmonary graft failure in a heart/lung transplant recipient. The major characteristics were alveolar fibrosis and a restrictive physiological deficit. Epstein-Barr virus was implicated as an aetiological agent using immunohistochemical analysis and by a response to treatment with ganciclovir.

Adult↗

PubMed1996

Cleavage of structural components of mammalian vitreous by endogenous matrix metalloproteinase-2.

Our goal was to determine if the major endogenous vitreous matrix metalloproteinase (MMP-2) could digest known collagenous components of the vitreous body. Matrix metalloproteinase-2 and its associated inhibitors were isolated from porcine vitreous by affinity column chromatography. The inhibitors were inactivated by chemical modification with dithiothreitol and iodoacetamide. The latent MMP-2 was then activated with the organomercurial, p-aminophenyl mercuric acetate (APMA). Bovine vitreous fibrillar collagens (types II, V/XI and IX) were isolated by pepsin extraction and differential salt precipitation. Intact type IX collagen was purified by selective salt precipitation followed by ion exchange and size exclusion chromatography. These isolated collagens were incubated for 6 to 24 h with different concentrations of activated MMP-2, and the extent of collagen degradation was analyzed. Activated MMP-2 was also introduced into freshly isolated vitreous gels and the degree of liquefaction was determined. Our results showed that the activated MMP-2 has no apparent effect upon type II collagen but can degrade type V/XI collagen and type IX collagen fragments (COL2 and COL2 + COL3). In addition, when the type IX collagen was in the intact helical form, MMP-2 appeared to selectively digest alpha 3 (IX) chains. This suggested that vitreous MMP-2 preferentially cleaved certain vitreous collagen chains into large fragments rather than small peptides. MMP-2 also disrupted the vitreous gel in vitro, releasing proteins but not hexuronic acid or sulfated glycosaminoglycans into the liquefied supernatant. We conclude that MMP-2 activity should be considered as a potential mechanism of vitreous liquefaction that is seen in aging and various pathological states.

Aging↗

PubMed1996

Cleavage of structural components of mammalian vitreous by endogenous matrix metalloproteinase-2

Our goal was to determine if the major endogenous vitreous matrix metalloproteinase (MMP-2) could digest known collagenous components of the vitreous body. Matrix metalloproteinase-2 and its associated inhibitors were isolated from porcine vitreous by affinity column chromatography. The inhibitors were inactivated by chemical modification with dithiothreitol and iodoacetamide. The latent MMP-2 was then activated with the organo-mercurial, p-aminophenyl mercuric acetate (APMA). Bovine vitreous fibrillar collagens (types II, V/XI and IX) were isolated by pepsin extraction and differential salt precipitation. Intact type IX collagen was purified by selective salt precipitation followed by ion exchange and size exclusion chromatography. These isolated collagens were incubated for 6 to 24 h with different concentrations of activated MMP-2, and the extent of collagen degradation was analyzed. Activated MMP-2 was also introduced into freshly isolated vitreous gels and the degree of liquefaction was determined. Our results showed that the activated MMP-2 has no apparent effect upon type II collagen but can degrade type V/XI collagen and type IX collagen fragments (COL2 and COL2 + COL3). In addition, when the type IX collagen was in the intact helical form, MMP-2 appeared to selectively digest alpha3 (IX) chains. This suggested that vitreous MMP-2 preferentially cleaved certain vitreous collagen chains into large fragments than small peptides. MMP-2 also disrupted the vitreous gel in vitro, releasing proteins but not hexuronic acid or sulfated glycosaminoglycans into the liquefied supernatant. We conclude that MMP-2 activity should be considered as a potential mechanism of vitreous liquefaction that is seen in aging and various pathological states. Keywords: matrix metalloproteinase; type II collagen; type IX collagen; type V/XI collagen; vitreous; pig

Journal Article↗

PubMed1996

Extreme hyperbilirubinemia associated with the use of anabolic steroids, health/nutritional supplements, and ethanol: response to ursodeoxycholic acid treatment.

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Adult↗

PubMed1996

Relating heat strain in the chemical defense ensemble to the ambient environment.

Management of military personnel in chemical protective clothing (CPC) is difficult. The purpose of this study was to test a 10 degrees C wet bulb globe temperature (WBGT) adjustment for CPC. Five male subjects walked for 1 hour at 400 kcal/hour twice in a U.S. military CPC at a WBGT = 20 degrees C, and once without protective clothing (NoPC) in a WBGT = 30 degrees C followed by a 45 minute seated recovery. No significant differences (p > 0.1) were observed between CPC trials, nor between the mean of the CPC trials and NoPC for heart rate, sweat rate, or change in rectal or mean skin temperatures during the work or recovery phases. Correlations between mean CPC and NoPC were all greater than 0.68. These results suggest minimal differences in responses between CPC and NoPC when the WBGT difference equaled 10 degrees C.

Adult↗

PubMed1995

Synthesis of the basic-helix-loop-helix region of the immunoglobulin enhancer binding protein E47 and evaluation of its structural and DNA binding properties.

The basic-helix-loop-helix (bHLH) region of the immunoglobulin enhancer binding protein E47 (IEB E47) was prepared in high yield by a solid-phase peptide synthesis methodology. Size-exclusion chromatography, sedimentation equilibrium and cross-linking data showed that the synthetic bHLH protein, 1, was dimeric, and higher-order aggregates of trimer and tetramer were also observed. The circular dichroism spectrum of 1 showed a high helical content, which increased upon addition of DNA containing the kappa E2 sequence. Gel mobility shift experiments showed that protein 1 bound sequence specifically to the kappa E2 sequence with a binding constant of 10(-10) M2, and had an affinity for other E box sequences as well. Comparisons between the co-crystal structure of IEB E47 with DNA and structural studies in solution showed lower helical contents in solution as would have been predicted from the crystal structure.

Amino Acid Sequence↗

PubMed1995

Health care executive education and training.

This paper examines the new situation of unprecedented change in the health care field--in which yet greater demands are in place for executive performance--and studies the educational and learning resources available to health care executives. The virtual transformation of the field requires new skill sets, competencies, and knowledge for high performing executives. How well is the field as a whole doing in providing appropriate learning opportunities? How well are health care organizations doing in effectively utilizing these resources of the field? What are the most crucial and immediately pertinent competencies needed; what are the topics of prime interest? And, are the overall learning efforts cost-effective with efficacious means of evaluation? These are the questions addressed by this article ... with the answers drawn from health care executives themselves.

Capitation Fee↗

PubMed1994

Empirical prediction of physiological response to prolonged work in encapsulating protective clothing.

Work in moderate or hotter environments while wearing encapsulating protective clothing (PC) results in heat storage and substantial diminution of work productivity, as well as being a potential health risk. An ability to predict the responses of workers using PC would be very useful. Predictions were made of work times at 21 degrees C of 15 subjects performing prolonged hard work (450 W gross) while wearing PC, based upon prior measures of short-duration bench stepping in PC and heart rate responses. A simple model was derived that shows good potential for predicting work time in moderate temperatures in PC; Total Time = 7.2 (bench step duration) - 34 (bench comfort) + 4 (height); R2 = 0.83, C.V. = 13. Unexpectedly, models that incorporated recovery heart rate as a variable were not as effective. With further refinement, the prediction approach tested in this study would be immediately useful for managing military and civilian personnel working in PC. Additionally, it could be utilized at minimal cost during routine training.

Adult↗