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Biomedical subjects

C Fields

Publications and source records attributed to C Fields.

At least 37 records · Page 2Linked to original sources
PubMed1991

The effect of moderate aerobic exercise on physical fitness among women 70 years and older.

This study investigated benefits of 26 weeks of moderate aerobic exercise for women 70 years or older. Sixteen healthy women with a mean age of 72.0 years were randomized into exercise (n = 10) and control groups (n = 6). The exercise group walked on a treadmill 3 times per week for 20 min, at 70% of maximum heart rate. Oxygen uptake VO2max expressed in l/min and ml.kg-1.min-1, total exercise time on the treadmill (TET), maximum heart rate (HRmax) and body mass index (BMI) were measured at baseline and 6 months. Two-way repeated measures analysis of variance (ANOVA) determined the effect of exercise intervention. Both measures of VO2max in addition to TET were significantly improved by the moderate training program, compared to the control group. VO2max in the exercise group increased by +/- 6.6% (S.E. 2.9) measured in l/min and 8.4% (S.E. 3.2) measured in ml.kg-1.min-1. TET increased by 25.4% (S.E. 4.9) in the exercise group. The ANOVA was unable to detect significance between the exercise and control groups for HRmax or BMI. All exercising subjects finished the program, apparently tolerating the intervention. The results indicate that healthy women over the age of 70 years can increase fitness measures with a moderate training program.

Age Factors↗
PubMed1990

Information content of Caenorhabditis elegans splice site sequences varies with intron length.

A database of sequences of 139 introns from the nematode Caenorhabditis elegans was analyzed using the information measure of Schneider et al. (1986) J. Mol. Biol. 128: 415-431. Statistically significant information is encoded by at least the first 30 nt and last 20 nt of C. elegans introns. Both the quantity and the distribution of information in the 5' splice site sequences differs between the typical short (length less than 75 nt) and rarer long (length greater than 75 nt) introns, with the 5 sites of long introns containing approximately one bit more information. 3' splice site sequences of long and short C. elegans introns differ significantly in the region between -20 and -10 nt.

Animals↗
PubMed1989

Predicting maximal oxygen uptake from treadmill testing in trained and untrained women.

This study was conducted to develop an equation to predict maximal oxygen uptake from exercise time during a standardized treadmill test in women aged 29 to 75 years before and after aerobic training. Treadmill tests were administered to 181 women with measurement of maximal oxygen uptake, and an equation predicting maximal oxygen uptake was derived: maximal oxygen uptake (ml.kg-1.min-1) = 10.34 + 1.29 (exercise time), r = 0.88, standard error of the estimate = 2.1, p less than 0.0001. Thirty-three women were retested after 6 and 12 months of aerobic exercise training. Maximal oxygen uptake was predicted from the equation developed and compared with the measured values at 6 and 12 months. The predicted and measured maximal oxygen uptake values after training were not significantly different. These results indicate that it is possible to predict maximal oxygen uptake for clinical purposes with a single equation from exercise time in untrained and trained women across a wide range of ages.

Adult↗
PubMed1989

Sequence comparisons of developmentally regulated collagen genes of Caenorhabditis elegans.

Collagen genes col-6, col-7 (partial), col-8, col-14 and col-19 from the nematode Caenorhabditis elegans were sequenced, and compared to the previously sequenced genes col-1 and col-2. The genes are between 1.0 and 1.2 kb in length, and each includes one or two short introns. The presumptive promoter regions contain sequences similar to the eukaryotic TATA promoter element. Two distinct, conserved sequences were found in the presumptive promoter regions of, respectively, the dauer larva-specific genes col-2 and col-6, and the primarily adult-specific genes col-7 and col-19. The domain structures of the collagen polypeptides are similar: each polypeptide contains two triple-helix forming (Gly-X-Y)n domains, one of 30-33 amino acids (aa), and the other of 127-132 aa. The latter domain is interrupted by one to three short (2-8 aa) non-(Gly-X-Y)n segments that occur at relatively conserved locations in each polypeptide. Sets of cysteine residues flank the (Gly-X-Y)n domains in all of the polypeptides. The genes can be placed into three families based upon amino acid sequence similarities. Genes within a family do not always exhibit similar developmental expression programs, suggesting that structural and regulatory regions of the genes have evolved separately. The codon usage in the genes is highly asymmetrical, with adenine appearing in the third position of 85% of the glycine codons, and 93% of the proline codons.

Amino Acid Sequence↗
PubMed1987

The effect of low-dose oral contraceptives on cardiorespiratory function, coagulation, and lipids in exercising young women: a preliminary report.

A study was undertaken to determine whether low-dose oral contraceptive usage would negate the beneficial effect of exercise on cardiorespiratory fitness, lipid and lipoprotein levels, and coagulation. Twelve exercising women were randomly allocated to groups of either oral contraceptive users or non-oral contraceptive users. When compared with results in the control group, maximal oxygen uptake (ml/kg1 X min1) decreased significantly in the oral contraceptive users during the 6-month period of observation. This was associated with an 8% decrease in both the oxygen uptake (2.34 to 2.17 L/min) and the oxygen pulse (12.1 +/- 3.2 to 11.2 +/- 2.2 ml/beat). The serum cholesterol, triglycerides, high-density lipoprotein/cholesterol, and high-density lipoprotein subfractions 2a and 2b levels were not altered. A significant increase in plasminogen activity was found in the oral contraceptive users: values increased from a coherent time average of 3.8 +/- 0.5 U/ml at baseline to 5.7 +/- 0.7 U/ml at 6 months; values returned to baseline levels 1 month after stopping the oral contraceptives (coherent time average of 3.9 +/- 0.6 U/ml; p less than 0.0001). No other significant changes were noted in the coagulation and anticoagulation factors studied. Low-dose oral contraceptive usage is associated with a decrease in functional aerobic capacity, but it does not impinge on the hemostatic mechanism or lipid-lipoprotein metabolism.

Adult↗
PubMed1986

Cardiorespiratory fitness evaluation in climacteric women: comparison of two methods.

Middle-aged women are becoming increasingly interested in aerobic exercise. For exercise to be meaningful, training needs to be performed at 70% to 85% of VO2max for 20 minutes, three times weekly. The graded exercise test is the standard method used to determine maximum oxygen uptake, but this test is impractical for use in clinical practice. A cross-sectional study evaluated 163 women between 35 and 75 years of age by graded exercise test and compared the result with a matched group of 121 women tested by bicycle ergometer (predicted maximum oxygen uptake). Bicycle testing and the graded exercise test had a similar range of values; this was confirmed by 29 climacteric women performing both tests (r = 0.789). Menopausal status has no effect on cardiorespiratory fitness: the predicted maximum oxygen uptake of age-matched menstruating women was 27.4 +/- 6.3 ml/kg/min and that of nonmenstruating women was 25.3 +/- 4.2 ml/kg/min (p greater than 0.05). Bicycle ergometry can thus be used as a screen to determine the cardiorespiratory fitness status of climacteric women.

Adult↗
PubMed1984

Acetazolamide and cerebral oxygenation in dogs.

Acetazolamide could theoretically impair oxygen delivery to cerebral tissue by inhibiting local acidification of capillary blood. There is considerable evidence, however, that acetazolamide improves cerebral oxygen tension. This experiment was designed to demonstrate increased deep cerebral oxygen tension after acetazolamide. Three groups of dogs were anesthetized with pentobarbital and ventilated with a respirator. A Teflon-coated stainless steel catheter was placed through a craniotomy into the parietal lobe and advanced into the corona radiata to monitor cerebral pO2 and pCO2 with a mass spectrometer. Group one dogs were normoxic and eucapneic. Group two dogs were hypoxemic, and Group three dogs were hypocapneic. After control cerebral and arterial gas tensions had been recorded, acetazolamide (30 mg kg-1) was injected intravenously. Cerebral gas tensions were monitored continuously and arterial gases were analyzed at 30, 60, 90 and 120 min. Cerebral oxygen tension was not decreased by acetazolamide in any of the dogs. Cerebral carbon dioxide tension was increased by acetazolamide in all dogs. We conclude that acetazolamide does not deplete cerebral oxygen tension even in the face of hypoxemia or acute hypocapnea.

Acetazolamide↗
PubMed1976

Experience in mass Papanicolaou screening and cytologic observations of teen-age girls.

This report is based on a seven-year retrospective analysis of computerized data available from the Chicago Board of Health's Cancer Control Section and its Cytology Laboratory. All patients included were medically indigent. The cytologic specimens were obtained by the VCE technique; all Papanicolaou smears were classified with both the numerical and descriptive systems for abnormal cytology. The study cohort was composed of 33,641 teen-age patients through age 19; 58 (1.7/1,000) had abnormal cytology (Class III, IV, or V). In Chicago, from 1962 through 1969, approximately 25 per cent of the total patient load were teen-agers under the age of 19 with an extremely low yield of suspect cytology: Class III = 1.6 per month; Class IV = 0.1 per month; Class V = 0.0 per month. The Chicago Board of Health has reduced the number of Papanicolaou smears taken on young women under the age of 19; however, this conceptual approach does not exclude women under age 19 who epidemiologically and/or clinically warrant the implementation of a Papanicolaou smear with the use of Friedell's "biologic age of the cervix" formula.

Adolescent↗
PubMed1970

Instrumental conditioning of the rat cardiac control systems.

The PR, PP, and RR intervals of the rat EKG were instrumentally conditioned using a variety of reinforcement schedules under computer control. The PR and PP intervals could be conditioned independently. Individual rats demonstrated either a steady shift of their response distribution or an abrupt change of an all-or-none variety. Some response distributions shifted continuously; others, through the growth of new response patterns in a manner reminiscent of hypothesis-testing behavior of human subjects. A study of the effects of single reinforcements showed that each reinforcement contributed to the learning behavior of the subject, in a well-defined but nonlinear fashion.

Animals↗
PubMed1970

Family counseling.

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Chromosome Aberrations↗
PubMed1969

Visual stimuli and evoked responses in the rat.

Rats were presented with a series of visual stimuli, each described by shape, size, and position. Cortical recordings were made in medial and lateral positions of rat visual cortex. Average responses were calculated and correlated. This analysis revealed that information regarding size was contained in electrical activity from medial areas, and informtion regarding shape in electrical activity from lateral areas.

Animals↗
PubMedDate not supplied

Domain organization and intron positions in Caenorhabditis elegans collagen genes: the 54-bp module hypothesis revisited.

The amino acid (aa) sequences of the polypeptides encoded by five collagen genes of the nematode Caenorhabditis elegans, col-6, col-7 (partial), col-8, col-14, and col-19, were determined. These collagen polypeptides, as well as those encoded by the previously sequenced C. elegans collagen genes col-1 and col-2, share a common organization into five domains: an amino-terminal leader, a short (30-33 aa) (Gly-X-Y)n domain, a non(Gly-X-Y) spacer, a long (127-132 aa) (Gly-X-Y)n domain, and a short carboxyl-terminal domain. The domain organizations and intron positions of these polypeptides were compared with those of the polypeptides encoded by Drosophila and Strongylocentrotus type IV, and vertebrate types I, II, III, IV, and IX collagen genes; the C. elegans collagen polypeptides are most similar to the vertebrate type IX collagens. It is suggested that the collagen gene family comprises two divergent subfamilies, one of which includes the vertebrate interstitial collagen genes, and the other of which includes the invertebrate collagen genes and the vertebrate type IV and type IX collagen genes. Only the vertebrate interstitial collagen genes display clear evidence of evolution via the tandem duplication of a 54-bp exon.

Amino Acid Sequence↗