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Biomedical subjects

S Green

Publications and source records attributed to S Green.

At least 181 records · Page 10Linked to original sources
PubMed1996

Methodological effects on the VO2-power regression and the accumulated O2 deficit.

The VO2-power regression and O2 demand predicted for a supra-VO2peak intensity (i.e., 432 W) were determined in seven well-trained male cyclists (mean +/- SD: VO2peak = 5.29 +/- 0.51 l.min-1), using five incremental exercise protocols. These protocols were either continuous (CON) or discontinuous (DISCON), and comprised five to eight work bouts ranging in intensity between 40% and 85% VO2peak; the work bouts differed in duration (4-15 min), and the VO2 was measured during the 4th minute (CON4, DISCON4), from min 4 to 6 (DISCON6), 8 to 10 (DISCON10), or 13 to 15 (DISCON15) of each work bout. The y-intercepts of the VO2-power regressions were not different (P > 0.05), whereas the slope was higher (P < or = 0.01) when determined using DISCON10 (12.7 +/- 0.9 ml.min-1.W-1) and DISCON15 (12.5 +/- 0.9 ml.min-1.W-1) compared with DISCON6 (12.2 +/- 1.0 ml.min-1.W-1), DISCON4 (11.6 +/- 1.1 ml.min-1.W-1) or CON4 (11.9 +/- 0.7 ml.min-1.W-1). The O2 demand (at 432 W) was also higher (P < or = 0.01) for DISCON10 (6.05 +/- 0.29 l.min-1) and DISCON15 (6.05 +/- 0.28 l.min-1) compared with DISCON6 (5.88 +/- 0.31 l.min-1), DISCON4 (5.70 +/- 0.31 l.min-1) and CON4 (5.82 +/- 0.25 l.min-1). This demonstrates that the O2 demand predicted for high power outputs depends on the incremental protocol used.

Adult↗
PubMed1996

A new method for the calculation of constant supra-VO2peak power outputs.

This investigation compared the variance in times to exhaustion among four different methods of supra-VO2peak power output calculation. Ten male subjects cycled to exhaustion at power outputs equivalent to 1) 120% VO2peak, 2) 6 W.kg-1, 3) 100% VO2peak + 10% of the peak anaerobic scope (PAS), and 4) 100% VO2peak + 20% of the mean anaerobic scope (MAS). PAS was defined as the difference between the peak power output (PPO) during a 30-s all-out cycle sprint and the power output at VO2peak MAS was defined as the difference between the mean power output (MPO) during a 30-s all-out cycle sprint and the power output at VO2peak. While the mean times to exhaustion for the four methods were not significantly different, the supra-VO2peak power output calculated as 120% VO2peak resulted in significantly more variance (P = 0.0173) in the times to exhaustion than did the power output equivalent to 20% MAS + 100% VO2peak (SE 16.2 s vs 6.9 s). The variance in time to exhaustion was significantly higher with the power output of 6 W.kg-1 than for the remaining three methods, while the variance in times to exhaustion at a power output of 10% PAS + 100% VO2peak was not significantly different from either 120% VO2peak or 20% MAS + 100% VO2peak. These results indicate that a supra-VO2peak power output that accounts for both aerobic ability and anaerobic work capacity (20% MAS + 100% VO2peak) results in less variance in time to exhaustion than a method which extrapolates the submaximal power output-VO2 relationship to a supramaximal intensity (120% VO2peak).

Adolescent↗
PubMed1996

The alpha1-fetoprotein locus is activated by a nuclear receptor of the Drosophila FTZ-F1 family.

The alpha1-fetoprotein (AFP) gene is located between the albumin and alpha-albumin genes and is activated by transcription factor FTF (fetoprotein transcription factor), presumed to transduce early developmental signals to the albumin gene cluster. We have identified FTF as an orphan nuclear receptor of the Drosophila FTZ-F1 family. FTF recognizes the DNA sequence 5'-TCAAGGTCA-3', the canonical recognition motif for FTZ-F1 receptors. cDNA sequence homologies indicate that rat FTF is the ortholog of mouse LRH-1 and Xenopus xFF1rA. Rodent FTF is encoded by a single-copy gene, related to the gene encoding steroidogenic factor 1 (SF-1). The 5.2-kb FTF transcript is translated from several in-frame initiator codons into FTF isoforms (54 to 64 kDa) which appear to bind DNA as monomers, with no need for a specific ligand, similar KdS (approximately equal 3 x 10(-10) M), and similar transcriptional effects. FTF activates the AFP promoter without the use of an amino-terminal activation domain; carboxy-terminus-truncated FTF exerts strong dominant negative effects. In the AFP promoter, FTF recruits an accessory trans-activator which imparts glucocorticoid reactivity upon the AFP gene. FTF binding sites are found in the promoters of other liver-expressed genes, some encoding liver transcription factors; FTF, liver alpha1-antitrypsin promoter factor LFB2, and HNF-3beta promoter factor UF2-H3beta are probably the same factor. FTF is also abundantly expressed in the pancreas and may exert differentiation functions in endodermal sublineages, similar to SF-1 in steroidogenic tissues. HepG2 hepatoma cells seem to express a mutated form of FTF.

Amino Acid Sequence↗
PubMed1996

Bone densitometry at a district general hospital: evaluation of service by doctors and patients.

OBJECTIVE: To assess doctors' and patients' views about a district general hospital bone densitometry service and to examine existing practice to influence future provision. DESIGN: Three postal surveys: (a) of doctors potentially using the service, (b) of patients undergoing a bone densitometry test during a six month period, and (c) of the referring doctors of the patients undergoing the test. SETTING: Bone densitometry service at South Cleveland Hospital, Middlesbrough and two district health authorities: South Tees and Northallerton. SUBJECTS: All general practitioners (n=201) and hospital consultants in general medicine, rheumatology, obstetrics and gynaecology, orthopaedics, radio therapy and oncology, haematology, and radiology (n=61); all patients undergoing an initial bone densitometry test (n=309) during a six month period; and their referring doctors. MAIN MEASURES: Service awareness and use, knowledge of clinical indications, test results, influence of test results on patient management, satisfaction with the service and its future provision. RESULTS: The overall response rates for the three surveys were 87%, 70%, and 61%. There was a high awareness of the service among doctors and patients; 219(84%) doctors were aware and 155 of them (71%) had used it, and patients often (40%) suggested the test to their doctor. The test was used for a range of reasons including screening although the general use was consistent with current guidelines. Two hundred (65%) bone densitometry measurements were normal, 71(23%) were low normal, and 38(12%) were low. Although doctors reported that management of patients had been influenced by the test results, the algorithm for decision making was unclear. Patients and doctors were satisfied with the service and most (n=146, 68%) doctors wanted referral guidelines for the service. CONCLUSIONS: There was a high awareness of, use of, and satisfaction with the service. Patients were being referred for a range of reasons and a few of these could not be justified, many tests were normal, and clinical decision making was not always influenced by the test result. It is concluded that bone densitometry services should be provided but only for patients whose management will be influenced by test results and subject to guidelines to ensure appropriate use of the technology.

Absorptiometry, Photon↗
PubMed1996

Adjuvant CMFVP versus adjuvant CMFVP plus ovariectomy for premenopausal, node-positive, and estrogen receptor-positive breast cancer patients: a Southwest Oncology Group study.

PURPOSE: To determine whether the addition of surgical ovariectomy to standard chemotherapy prolongs disease-free survival (DFS) and overall survival in premenopausal patients with estrogen receptor (ER)-positive operable breast cancer with positive axillary nodes. PATIENTS AND METHODS: Three hundred fourteen premenopausal patients with ER-positive, node-positive breast cancer were enrolled between July 1979 and July 1989. Patients were stratified according to number of involved nodes and type of primary surgery and randomized to receive either of the following: (1) cyclophosphamide 60 mg/m2/d by mouth for 1 year, methotrexate 15 mg/m2 intravenously (i.v.) weekly for 1 year, fluorouracil (5-FU) 400 mg/m2 i.v. weekly for 1 year, vincristine .625 mg/m2 i.v. weekly for the first 10 weeks, and prednisone weeks 1 to 10 with doses decreasing from 30 mg/m2 to 2.5 mg/m2 (CMFVP); or (2) bilateral ovariectomy followed by CMFVP. RESULTS: The median follow-up time is 7.7 years and the maximum 13.2 years. Treatment arms are not significantly different with respect to either survival or DFS (one-sided log-rank, P = .55 and .70, respectively). The 7-year survival rate is 71% on the CMFVP arm and 73% on CMFVP plus ovariectomy. No significant differences were observed in node or receptor level subsets. CONCLUSION: We conclude that, in this study, the addition of ovariectomy did not improve results over chemotherapy alone in the treatment of premenopausal women with node-positive, ER-positive, operable breast cancer. Our sample size was too small to detect a small improvement. The death hazards ratio of CMFVP/CMFVP plus ovariectomy was 1.22 (95% confidence interval [CI], .79 to 1.89).

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Smoking policy and cessation in an inner-city hospital.

Hospital policies regarding cigarette smoking can affect the smoking habits of employees, patients, and visitors. Successful smoking policy development and impact have been reported in a number of hospitals. These reports have been from financially secure or university hospitals. This article reports on the policy experience at Interfaith Medical Center, a public hospital serving an economically disadvantaged black inner-city community. Policy implementation and smoking cessation efforts were directed by a broad-based hospital committee. An employee survey demonstrated support for a policy restricting but not banning smoking (89% of nonsmokers, and 80.2% of smokers). Among smoking employees, 87.6% wanted to quit. A policy restricting smoking to designated areas in the cafeteria and coffee shop was enacted. Health fairs and smokeout contests were enthusiastically received and resulted in short-term cessation verified by exhaled carbon monoxide levels. Assemblies where ex-smokers were given "Hall of Fame" certificates, "stop smoking" art contests, and a "stop smoking hotline" generated further cessation activity. The department of medicine, in cooperation with the National Heart, Lung, and Blood Institute's Smoking Education Program, set up a training program for residents on how to help patients quit. Overall, the smoking prevalence, attitudes, and enthusiasm to quit were similar to previous reports in financially secure hospitals. Unfortunately, lack of resources and staff turnover led to dissolution of the program. Institutional stability and a funding source are critical for the long-term success of hospital smoking cessation programs.

Adult↗
PubMed1996

Positioning the patient for surgery.

The aim of this paper is to identify some of the potential hazards involved with the positioning of the patient on the operating table prior to surgery. The development of good practice within this area is essential to both the patient and staff so helping to avoid unnecessary post operative complications for the patient and avoiding unnecessary potential problems for the staff. The UKCC guidelines are quite clear regarding the nurse's role in patient care: The nurse must always promote and safeguard the interests and well-being of the patient and ensure that no action or omission in her area of responsibility is detrimental to the patient. The nurse must have regard to the environment and its physical, psychological and social effects on the patient and to the adequacy of resources and inform appropriate authorities of any circumstances which could place the patient at risk or which militate against safe standards of practice. The nurse must endeavour to achieve, maintain and develop knowledge, skills and competence to meet the needs of the patient at all times.

Beds↗
PubMed1996

Nitrous oxide--a potential hazard.

The aims of this article are to examine the potential hazards of exposure to nitrous oxide gases on personnel working within the perioperative environment and to provide an insight into the history of nitrous oxide, its use in anaesthetics and its contribution to global air pollution and the greenhouse effect.

Air Pollutants, Occupational↗
PubMed1995

Maintaining low HIV seroprevalence in populations of injecting drug users.

OBJECTIVES: To describe prevention activities and risk behavior in cities where human immunodeficiency virus (HIV) was introduced into the local population of injecting drug users (IDUs), but where seroprevalence has nevertheless remained low (< 5%) during at least 5 years. DESIGN AND SETTING: A literature search identified five such cities: Glasgow, Scotland; Lund, Sweden; Sydney, New South Wales, Australia; Tacoma, Wash; and Toronto, Ontario. Case histories were prepared for each city, including data on prevention activities and current levels of risk behavior among IDUs. PARTICIPANTS: Injecting drug users recruited from both drug treatment and non-treatment settings in each city. INTERVENTIONS: A variety of HIV prevention activities for IDUs had been implemented in each of the five cities. RESULTS: There were three common prevention components present in all five cities: (1) implementation of prevention activities when HIV seroprevalence was still low, (2) provision of sterile injection equipment, and (3) community outreach to IDUs. Moderate levels of risk behavior continued with one third or more of the IDUs reporting recent unsafe injections. CONCLUSIONS: In low-seroprevalence areas, it appears possible to severely limit transmission of HIV among populations of IDUs, despite continuing risk behavior among a substantial proportion of the population. Pending further studies, the common prevention components (beginning early, community outreach, and access to sterile injection equipment) should be implemented wherever populations of IDUs are at risk for rapid spread of HIV.

HIV Infections↗
PubMed1995

Identification and characterization of DNA elements implicated in the regulation of CYP4A1 transcription.

We have identified a peroxisome proliferator response element (PPRE) approx. 4300 nucleotide upstream of the rat cytochrome P-450 CYP4A1 gene. Two members of the steroid-hormone-receptor superfamily, the peroxisome proliferator-activated receptor-alpha (PPAR alpha) and the retinoid X receptor-alpha (RXR alpha), bind specifically to this element as a heterodimer, and this element confers responsiveness to the peroxisome proliferator Wyeth-14,643 when tested in co-transfection assays. A second element, located 35 nucleotides further upstream, fails to bind PPAR alpha/RXR alpha heterodimers and is unresponsive to Wy-14,643 in co-transfection assays. Both elements are, however, responsive to 9-cis-retinoic acid in the presence of RXR alpha, when tested in the co-transfection assay. As RXR alpha fails to bind to either element as a homodimer, we suggest that RXR alpha interacts with PPAR alpha to regulate transcription via the proximal element, and interacts with some other cellular factor to regulate transcription via the more distal element. This is consistent with previous reports that a number of peroxisome proliferator-regulated genes contain PPRE-like elements as part of their regulatory sequences, which may be recognized by several receptor combinations. This provides further evidence that PPARs and their co-factors are important in mediating the pleiotropic action of peroxisome proliferators.

Animals↗
PubMed1995

A macrophage receptor for oxidized low density lipoprotein distinct from the receptor for acetyl low density lipoprotein: partial purification and role in recognition of oxidatively damaged cells.

The binding and uptake of oxidatively modified low density lipoprotein (OxLDL) by mouse peritoneal macrophages occurs, in part, via the well characterized acetyl LDL receptor. However, several lines of evidence indicate that as much as 30-70% of the uptake can occur via a distinct receptor that recognizes OxLDL with a higher affinity than it recognizes acetyl LDL. We describe the partial purification and characterization of a 94- to 97-kDa plasma membrane protein from mouse peritoneal macrophages that specifically binds OxLDL. This receptor is shown to be distinct from the acetyl LDL receptor as well as from two other macrophage proteins that also bind OxLDL--the Fc gamma RII receptor and CD36. We suggest that this OxLDL-binding membrane protein participates in uptake of OxLDL by murine macrophages and also represents a receptor responsible for macrophage binding and phagocytosis of oxidatively damaged cells.

Animals↗
PubMed1995

Time-integrated blood lead concentration is a valid surrogate for estimating the cumulative lead dose assessed by tibial lead measurement.

The concentration of lead in tibia (Pb-T) was measured in vivo by a 109Cd K-shell X-ray fluorescence technique in 123 workers from a primary lead smelter (age: mean, 45 years; range, 30-61; duration of employment: mean, 20 years; range, 7-45). Their cumulative blood lead index (CBLI) was also calculated on the basis of the blood lead (Pb-B) records available from the company's medical files. Geometric mean for Pb-T was 49 micrograms Pb/g bone mineral (range, 15-167). The company's health surveillance programs, implemented since 1945, resulted in Pb-B values which rarely exceeded 70 micrograms Pb/dl whole blood. Pb-B at the time of Pb-T measurement averaged 31 micrograms Pb/dl (range, 6-62) and the geometric mean for CBLI amounted to 803 micrograms Pb/dl x year (range, 220-2130). Despite various assumptions and uncertainties inherent in the assessment of the cumulative lead dose through Pb-T measurement or CBLI calculation, the relation between both variables in the present lead smelter populations is very strong (rpearson = 0.80, P < 0.0001; age explained at the most 9.5% of the variance). The slope of the regression equation of log Pb-T vs log CBLI showed that a doubling of CBLI also corresponds to doubling of Pb-T. It may be concluded that a sound calculation of CBLI represents a valid surrogate for estimating the life time integrated dose of lead as assessed by the measurement of cortical bone lead (e.g., in tibia).

Adult↗
PubMed1995

Liposomal vaccines.

Liposomes have been used therapeutically to deliver drugs to certain anatomical sites. The use of liposomes to deliver antigens, although not a new concept, has received less attention. At least two vaccines of nearly identical liposome base composition to our vaccines have been tested in humans. A malaria vaccine study showed that the liposomal preparation is quite safe: reaction profiles of volunteers receiving the vaccine demonstrated little reactivity and virtually no pyrogenicity (14). The concentration of MPLA in the vaccine was substantially higher (nearly 50,000 times) than the pyrogenic dose of free lipid A. The same vaccine, but different antigen (gp120, an HIV protein), was tested in volunteers and had the same lack of toxicity (27). In both studies, antibodies and cytotoxic cells specific for the respective antigens were produced. We have several subunit vaccines under development for infectious diseases (gram negative sepsis, fungal infections, protozoan infections), metabolic disorders (hypercholesterolemia, diabetic retinopathy, macular degeneration), and neoplastic diseases (multi-drug resistant cancer, primary and metastatic tumors, and angiogenic hyperproliferative disorders). In each case, one or more antigens were identified that might be useful in immunologic control of biologic proliferation (i.e., pathogen or tumor growth, rise in serum cholesterol, growth of blood vessels). We anticipate that at least one of these vaccines will be ready for testing in humans in the next calendar year.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Effect of end-point cadence on the maximal work-time relationship.

This study examined the effect of end-point cadence on the parameters of the work-time relationship determined for cycle ergometry. Eight male subjects completed four maximal tests on an electrically-braked cycle ergometer that regulated a constant power output independent of cadence. The power outputs imposed ranged between an average of 259 W and 403 W, whereas the corresponding durations ranged between 139 s and 1691 s. During each test subjects were required to maintain a cadence of 80-90 rpm. Accumulated time to end-point cadences of 70, 60 and 50 rpm were recorded. The four work-time determinations for each of three end-point cadences were used to determine linear relationships between work and time, yielding both a y-intercept, which represents anaerobic work capacity, and a slope, which is termed critical power (CP), for each end-point cadence. There was a significant increase in the y-intercept as end-point cadence decreased from 70 to 60 rpm (F[1,7] = 36.7, p < 0.001) or 70 to 50 rpm (F[1,7] = 80.1, p < 0.001), but not from 60 rpm to 50 rpm (F[1,7] = 3.28, p > 0.05). In contrast, there was no effect of end-point cadence on CP (F[2,14] = 1.89, p < 0.05). These results demonstrate that the end-point cadence selected to terminate tests only affects the y-intercept of the work-time relationship. To control for this effect, the cadence at which each test is terminated should be standardised if determination of anaerobic work capacity, as represented by the y-intercept, is required.

Adult↗
PubMed1995

The oxygen uptake-power regression in cyclists and untrained men: implications for the accumulated oxygen deficit.

The regression of oxygen uptake (VO2) on power output and the O2 demand predicted for suprapeak oxygen uptake (VO2peak) exercise (power output = 432 W) were compared in ten male cyclists [C, mean VO2peak = 67.9 (SD 4.2) ml.kg-1.min-1] and nine active, yet untrained men [UT, mean VO2peak = 54.1 (SD 6.5) ml.kg-1.min-1]. The VO2-power regression was determined using a continuous incremental cycle test (CON4), performed twice, which comprised several 4-min exercise periods progressing in intensity from approximately 40%-85% VO2peak. Minute ventilation (VE), heart rate (HR), respiratory exchange ratio (R), blood lactate concentration ([la-]b) and rectal temperature (Tre) were measured at rest and during CON4. The slope of the VO2-power regression was greater (P < or = 0.05) in C [12.4 (SD 0.7) ml.min-1.W-1] compared to UT [11.7 (SD 0.4) ml.min-1.W-1]; as a result, the O2 demand (at 432 W) was also higher (P < or = 0.05) in C [5.97 (SD 0.23) l.min-1] than UT [5.70 (SD 0.15) l.min-1]. Exercise R and [la-]b were lower (P < or = 0.05) in C in comparison to UT at all power outputs, whereas VE and HR were relatively lower (P < or = 0.05) in C at power outputs approximating 180 W, 220 W and 270 W. Differences in fat metabolism estimated over the first three power outputs accounted for approximately 19% of the difference in VO2-power slopes between the groups and up to 46% of the difference in VO2 at a given intensity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗