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Biomedical subjects

S M Rogers

Publications and source records attributed to S M Rogers.

32 records · Page 2Linked to original sources
PubMed1988

Characteristics of Five New Photoautotrophic Suspension Cultures Including Two Amaranthus Species and a Cotton Strain Growing on Ambient CO(2) Levels.

Suspension cultures of cotton (Gossypium hirsutum), Amaranthus cruentus, A. powellii, Datura innoxia, and a Nicotiana tabacum-N. glutinosa fusion hybrid were adapted to grow photoautotrophically under continuous light. The cotton strain grew with an atmosphere of ambient CO(2) (about 0.06 to 0.07% in the culture room) while the other strains required elevated CO(2) levels (5%). Photoautotrophy was indicated by the requirement for CO(2) and for light for growth. The strains grew with doubling times near 14 days and had from 50 to 600 micrograms of chlorophyll per gram of fresh weight. The cells grew in small to moderate sized clumps with cell sizes from 40 to 70 micrometers (diameter). Like most photoautotrophic cultures described so far the ribulose 1,5-bisphosphate carboxylase (RuBPcase) activity levels were well below those of mature leaves. The phosphoenolpyruvate carboxylase levels were not elevated in the C(4)Amaranthus species. The cells showed high dark respiration rates and had lower net CO(2) fixation under high O(2) conditions. Dark CO(2) fixation rates ranged from near 10 to 30% of that in light. Fluorescence emission spectra measurements show that the cell antenna pigments systems of the four strains examined are similar to that of chloroplasts of green plants. The cotton strain which was capable of growth under ambient CO(2) conditions showed the unique properties of a high RuBPcase activation level in ambient CO(2) and a stable ability to show net CO(2) fixation in 21% O(2) conditions.

Journal Article↗
PubMed1987

Photosynthetic characteristics of a photoautotrophic cell suspension culture of soybean.

A soybean suspension culture (SB-P) which can grow photoautotrophically in 5% CO(2) will not grow in ambient CO(2) levels. This elevated CO(2) requirement seems to be due to the additive effects of a number of factors. The in vivo activity of ribulose-1,5-bisphosphate carboxylase (RuBPcase) is much lower in the SB-P cells, compared to soybean plants. This may be due to the low light intensity used to culture the cells, which has been shown to decrease both the amount and activity in whole plants, resulting in a low rate of net photosynthesis. The RuBPcase activation level is also lowered in air CO(2) levels. The presence of the liquid medium raises the cells CO(2) compensation concentration (the CO(2) concentration reached when the rates of CO(2) fixed by photosynthesis and the CO(2) respired by the cells are equal). These factors, coupled with the high respiratory loss of CO(2) all contribute to reduced net photosynthesis in air, resulting in a photosynthetic capacity that is inadequate for cell survival. Active cell division, low photosynthetic capacity, elevated respiration, and a low ratio of RuBPcase(initial)/phosphoenolpyruvate carboxylase are traits that SB-P cells share with young leaf cells, indicating SB-P cell physiology may be comparable to that of young expanding leaves rather than to that of mature leaves.

Journal Article↗
PubMed1987

Review: first-pass metabolism by the gastrointestinal mucosa.

The bioavailability of orally administered drugs may be reduced due to presystemic elimination. The first-pass effect can occur in the gastrointestinal tract, the liver and lung. Although the liver is the main drug metabolizing organ in the body, the gut wall can play an important role in the first-pass metabolism of certain drugs. Both phase I (preconjugation) and phase II (conjugation) reactions have been described. However, while the oxidative metabolic capacity of the intestinal mucosa is considerably smaller than that of the liver, the activity of conjugation reactions in the gut may be close to that of the liver, and in some cases may exceed it. Sulphate conjugation is particularly important for steriod hormones such as ethinyloestradiol, and for the beta-adrenoceptor stimulants isoprenaline and isoetharine. Glucuronidation has been demonstrated to occur in man for morphine, paracetamol and oestrogens. Significant drug--drug interactions have been described involving drugs undergoing sulphate conjugation. The study of intestinal metabolism in vivo is difficult in man since direct methods (for example, hepatic portal vein catheterization) is justified in only a small number of patients. Therefore, much of our present understanding has been derived from various in-vitro studies involving intestinal sheets, mucosal biopsies, isolated enterocytes and microsomal preparations.

Animals↗
PubMed1987

Paracetamol interaction with oral contraceptive steroids: increased plasma concentrations of ethinyloestradiol.

The effect of a single dose of paracetamol (1 g) on plasma concentrations of the oral contraceptive steroids ethinyloestradiol (EE2) and levonorgestrel (LNG) has been studied in six healthy female volunteers. The area under the plasma concentration-time curve (AUC0-24) of EE2 was significantly increased following paracetamol administration by 22% (control 2221 +/- 291; following paracetamol, 2702 +/- 452 pg ml-1 h; mean +/- s.d.; P less than or equal to 0.05). The greatest effect was evident in the time period 0-3 h. There was a significant decrease in the AUC of EE2-sulphate after paracetamol (7736 +/- 3791 pg ml-1 h) compared with control (13161 +/- 4535 pg ml-1 h; P less than or equal to 0.05). Plasma concentrations of LNG were unaltered by concurrent paracetamol administration. We conclude that the administration of a single 1 g dose of paracetamol causes an increase in plasma concentrations of EE2 as a result of a reduction in the sulphation of the steroid. This interaction may be of clinical significance in women on oral contraceptive steroids who regularly take paracetamol.

Acetaminophen↗
PubMed1987

Intestinal metabolism of ethinyloestradiol and paracetamol in vitro: studies using Ussing chambers.

The intestinal mucosal metabolism of ethinyloestradiol (EE2) and paracetamol (P) has been studied in vitro in Ussing chambers. Histologically normal jejunum or ileum was obtained from 19 patients undergoing various resections. The muscularis externa was stripped off the mucosa and the mucosal sheets mounted between two perspex chambers. Tissue viability was routinely assessed by measurement of the transmural potential difference. The percentage of steroid in the serosal chamber, 2 h after addition of EE2 (2 microCi; 80 ng) to the mucosal chamber was 2.3 +/- 0.8% (mean +/- s.d.) which comprised unconjugated drug (0.4 +/- 0.3%), sulphate conjugates (0.7 +/- 0.5%) and glucuronides (0.9 +/- 0.8%). In the mucosal chamber, 56.6 +/- 11.4% was unconjugated steroid, 33.3 +/- 12.4% sulphate conjugates and 2.1 +/- 2.3% glucuronides. Small amounts of the oxidation products 2-hydroxy and 16-hydroxy-EE2 were present. At 2 h, the percentage of paracetamol in the serosal chamber was 3.2 +/- 1.4% (of added P; 2 microCi; 50 ng) of which 0.5 +/- 0.3% was paracetamol sulphate (PS) and 0.1% was paracetamol glucuronide (PG). In the mucosal chamber 2.4 +/- 0.8% and 1.0 +/- 0.2% was present as PS and PG respectively. The total amount of paracetamol conjugated was approximately 4.0%. When paracetamol in the mucosal chamber was increased to 50 micrograms (i.e. by a factor of 1000) there was a decrease in the percentage of added drug metabolized to PS and an increase in formation of PG. The glucuronide:sulphate ratio was increased from 0.34 to 3.56. Competition for sulphation was evident when both paracetamol and EE2 were presented to the intestinal mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaminophen↗
PubMed1987

Pharmacokinetics of contraceptive steroids in patients with cystic fibrosis.

The pharmacokinetics of the commonly used contraceptive steroids ethinyloestradiol and levonorgestrel were investigated after oral and intravenous administration in six women with cystic fibrosis. The results were compared with data obtained from healthy women of similar age. The total body clearance of ethinyloestradiol was significantly higher in the patients with cystic fibrosis (0.61 (SD 0.19) l/h/kg) than in control women (0.32 (0.16) l/h/kg; p less than 0.02). In addition, the oral bioavailability of ethinyloestradiol was greater in women with cystic fibrosis than in controls (76.9% (11.7%) compared with 47.3% (7.5%); p less than 0.001). As a result of these two changes, the area under the plasma concentration--time curve after an oral dose of ethinyloestradiol was similar in patients and controls. The pharmacokinetics of levonorgestrel did not differ significantly between patients with cystic fibrosis and healthy women. The data suggest that women with cystic fibrosis will receive similar contraceptive protection from these steroids as do healthy women.

Adult↗
PubMed1986

Accidental burn deaths to Egyptian women of reproductive age.

Among women of reproductive age in Menoufia, Egypt, deaths from burns constitute a major public health problem. Burns account for 9 per cent of the deaths occurring to women aged 15-49, and were the third cause of death (after disease of the circulatory system and complications of pregnancy and childbirth). Nearly two-thirds of the burns were caused by kerosene cooking stoves. The data were obtained from a population-based survey of all deaths to women of reproductive age. There were 1691 deaths from all causes during the 3 years of the study, 152 of these were due to burns. Information on the cause of death was gathered from interviews with surviving family members; interviews were reviewed by physicians and a cause of death established. Although hospital-based studies provide valuable information for the management of burn injuries presenting for treatment, establishing rates of injury, comparing the incidence in one population group relative to another, or comparing the incidence of burns relative to other forms of injury requires a population-based study.

Accidents, Home↗
PubMed1986

Reproductive mortality in two developing countries.

Reproductive mortality includes mortality attributable to pregnancy, termination of pregnancy, childbirth and its sequelae, and contraception. Reproductive mortality has been estimated for the United Kingdom, the United States, and for states of the US. However, it has not previously been measured for developing countries, where maternal mortality often remains distressingly high. This paper reports on data from one governorate of Egypt, where reproductive mortality was 46 per 100,000 married women ages 15-49 (2.2 per cent of this was attributable to contraception), and one province of Indonesia, where reproductive mortality was 70 per 100,000 (of which 1.4 per cent was due to contraception). In both locations, complications of pregnancy and childbirth were a leading cause of death in the age group studied (the first cause in Indonesia, second in Egypt). Contraceptive prevalence was 24 per cent of married women ages 15-49 in Egypt and 48 per cent of this age group in Indonesia.

Adolescent↗
PubMed1984

IUD--related uterine perforation: an epidemiologic analysis of a rare event using an international dataset.

An international dataset of 21,610 IUD insertions revealed 41 uterine perforations occurring at the time of, or subsequent to, insertion. Dat were collected on standard forms. Perforations were classified as confirmed, probable, or possible, based on the clinician's judgement and subsequent management. The uterine perforation rate was estimated as between 1.9 and 3.6/1000 insertions. 13 of the total 41 perforations were reported from 2 of 72 cooperating clinics. In 1 clinic, this center-clustering phenomenon suggested an effect of a high risk device. In the other clinic, the effect of insertor (operator) inexperience was indicated. A case-control analysis delineated previous cesarean section as a host risk factor (P0.05, McNemar's chi square). Further investigation of this association by similar case-control studies is recommended.

Age Factors↗
PubMed1972

Effect of ribosomal wash factors on inhibition by chloramphenicol.

In vitro protein-synthesizing systems from Escherichia coli can be categorized as either chloramphenicol-sensitive or chloramphenicol-insensitive. The chloramphenicol-sensitive systems used in this study required the presence of factors removed from ribosomes with 1.0 m NH(4)Cl when chromatographically purified ribosomes were used for amino acid incorporation. These ribosomal wash factors inhibited but did not eliminate amino acid incorporation in chloramphenicol-insensitive systems. For both systems, addition of increasing amounts of the ribosomal wash factors increased the sensitivity to chloramphenicol inhibition.

Amino Acids↗
PubMedDate not supplied

Sexual behavior in the United States 1930-1990: trends and methodological problems.

BACKGROUND AND OBJECTIVES: Arguments for population-based research on patterns of sexual behavior are reviewed, and survey data are used to illustrate the insights that can be gained from such research. STUDY DESIGN: Reports of sexual behavior obtained in surveys of large probability samples of the U.S. population are analyzed and compared to make inferences about changes in the age of onset of sexual intercourse and the patterns of heterosexual and same-gender sexual behaviors of American men and women who entered adulthood during the period from 1930 to 1990. RESULTS: Strong trends are documented for both a decline in the reported age at first heterosexual intercourse and an increase in the numbers of heterosexual partners reported during adulthood. Similar evidence on patterns of same-gender contact indicate a relatively stable prevalence of reported male-male contact for cohorts of men born from the 1930s through the 1960s. Preliminary analyses suggest, however, that there has been a substantial increase in the proportion of women reporting female-female sexual contact during adulthood. Although the analyses require refinement, it appears that the prevalence of reported female-female contact may have increased by a factor of 3 to 4 for cohorts of women born between the 1930s and the 1960s. CONCLUSIONS: Although the trends in reported behaviors are robust, inferences about behavior, pre se, rest on the assumption that reporting biases were equivalent across cohorts. Methodological challenges in the interpretation of such findings and new technologies for conducting such research are described.

Adolescent↗
PubMedDate not supplied

Correlates of sexually transmitted bacterial infections among U.S. women in 1995.

CONTEXT: Sexually transmitted diseases (STDs) of bacterial origin such as gonorrhea and chlamydial infection can lead to pelvic inflammatory disease (PID) and infertility. Identifying behaviors and characteristics associated with infection may assist in preventing these often asymptomatic diseases and their sequelae. METHODS: Data from 9,882 sexually active women who participated in the 1995 National Survey of Family Growth describe the characteristics of women who report a history of infection with a bacterial STD or of treatment for PID. Multivariate analysis is used to determine which demographic characteristics and sexual and health-related behaviors affect the likelihood of infection or the occurrence of complications. RESULTS: Overall, 6% of sexually active women reported a history of a bacterial STD, and 8% reported a history of PID. Women who first had sexual intercourse before age 15 were nearly four times as likely to report a bacterial STD, and more than twice as likely to report PID, as were women who first had sex after age 18. Having more than five lifetime sexual partners also was associated with both having an STD and having PID. PID was more common among women reporting a history of a bacterial STD (23%) than among women who reported no such history (7%). In multivariate analyses, age, race, age at first intercourse and lifetime number of sexual partners had a significant effect on the risk of a bacterial STD. Education, age, a history of IUD use, douching and a history of a bacterial STD had a significant impact on the risk of PID, but early onset of intercourse did not, and lifetime number of partners had only a marginal effect. CONCLUSIONS: The pattern of characteristics and behaviors that place women at risk of infection with bacterial STDs is not uniform among groups of women. Further, the level of self-reported PID would suggest higher rates of gonorrhea and chlamydial infection than reported.

Adolescent↗
PubMedDate not supplied

Early symptoms and discontinuation among users of oral contraceptives in Sri Lanka.

The relationship between symptoms reported during the first two cycles of oral contraceptive use and subsequent discontinuation was studied using data from a comparative clinical trial of two oral contraceptives (standard dose and low dose) in Sri Lanka. Among 24 symptoms considered, the most commonly reported were headache, nausea, irritability, dizziness, tiredness, intermenstrual spotting/bleeding, backache, abdominal pain, vomiting, and hair loss. Headache, nausea, vomiting, and dizziness were closely associated with each other and strongly predictive of discontinuation for both drugs. No other symptoms were consistently associated with each other or with subsequent discontinuation. Intermenstrual spotting/bleeding was associated with later discontinuation of the standard dose preparation, but not the lower dose preparation.

Adolescent↗