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Biomedical subjects

A Taylor

Publications and source records attributed to A Taylor.

At least 307 records · Page 17Linked to original sources
PubMed1997

Characterization of intrafollicular steroid hormones, inhibin, and follistatin in women with and without polycystic ovarian syndrome following gonadotropin hyperstimulation.

The etiology of polycystic ovary syndrome (PCOS) is unexplained. Since no major deficiencies are reported in serum FSH or inhibin, we hypothesized that abnormal levels of a paracrine modulator of FSH action within the ovary may be associated with the arrest of follicular growth seen in the PCOS ovary. Follicular fluid aspirates were collected from women with (n = 7) or without (n = 17) PCOS during oocyte retrieval for in vitro fertilization. Aspirates were assayed for total inhibin, inhibin A (InhA), inhibin B (InhB), and follistatin (FS), as well as for estradiol, progesterone (P4), androstenedione, and total protein. Hormone levels were compared between women with and without PCOS using all aspirates (some of which were collected from multiple follicles at once) and also between aspirates containing fluid from a single follicle only (PCOS, n = 30; non-PCOS, n = 107). P4 levels were significantly (p < 0.01) reduced in PCOS versus non-PCOS women as evidenced by analysis of all follicles as well as in single-follicle aspirates only. In addition, InhA, P4, and FS increased with follicle volume, and InhB decreased significantly in non-PCOS, but not in PCOS, follicles. Therefore, although follicular development can be induced in PCOS patients with gonadotropins, hormonal responses within the ovary appear inappropriate in terms of concentrations or patterns of secretion. These data support the concept that PCOS is associated with a deficit in the paracrine control of folliculogenesis.

Adult↗
PubMed1997

Phenotypic and genotypic discrimination of strains of Salmonella serotype Eimsbuettel from human and animal sources.

One hundred isolates of Salmonella serotype Eimsbuettel from various human, animal and environmental sources in six countries were typed and shown to belong to five ribotypes, five biotypes and eight different ribotype/biotype groups, one of which, ribotype 3/biotype 5, was represented among isolates from all six countries. Most of the Eimsbuettel isolates from Scotland belonged to ribotype 1/biotype 3, which was the epidemic strain involved in a large outbreak centred in a Glasgow maternity hospital in 1986. That strain was also responsible for almost all the human infections that occurred in the west of Scotland in the years of this study. However, isolates from human cases in the east of Scotland belonged to either ribotype 2/biotype 1 or ribotype 3/biotype 5, groups not found in the west of Scotland. Representatives of all three ribotype/biotype groups causing human infection in Scotland were also found among isolates from poultry or poultry-associated materials. Plasmids were carried by only 14% of isolates and so provided little additional strain discrimination. However, plasmid analysis suggested that Salmonella Eimsbuettel of ribotype 2/biotype 1 had the potential to enter the human food chain in the UK via meat or bone meal, animal feed and poultry.

Animals↗
PubMed1997

Multicenter trial validation of a camera-based method to measure Tc-99m mercaptoacetyltriglycine, or Tc-99m MAG3, clearance.

PURPOSE: To evaluate an improved camera-based method for calculating the clearance of technetium-99m mercaptoacetyltriglycine (MAG3) in a multicenter trial. MATERIALS AND METHODS: Tc-99m MAG3 scintigraphy was performed in 49 patients at three sites in the United States and Canada. The percentage of the injected dose of Tc-99m MAG3 in the kidney at 1-2, 1.0-2.5, and 2-3 minutes after injection was correlated with the plasma-based Tc-99m MAG3 clearances. The data were combined with the results obtained in 20 additional patients in a previously published pilot study. RESULTS: Regression models correlating the plasma-based Tc-99m MAG3 clearance with the percentage uptake in the kidney for each time interval were developed; there was no statistically significant difference among sites in the regression equations. Correction for body surface area statistically significantly (P < .005) improved the correlation coefficient for each time interval. For the 1.0-2.5-minute interval, the body surface area-corrected correlation coefficient for the four combined sites was .87, and it improved to .93 when one outlier was omitted from the analysis. Similar results were obtained with the other time intervals. Independent processing by two observers showed no clinically important differences in the percentage dose in the kidney or in relative function. CONCLUSION: An improved camera-based method to calculate the clearance of Tc-99m MAG3 was validated in a multicenter trial.

Adolescent↗
PubMed1997

Augmentation of deglutitive upper esophageal sphincter opening in the elderly by exercise.

Earlier studies have shown that the cross-sectional area of the deglutitive upper esophageal sphincter (UES) opening in healthy asymptomatic elderly individuals is reduced compared with healthy young volunteers. The aim of this study was to determine the effect of a head-raising exercise on swallow-induced UES opening and hypopharyngeal intrabolus pressure in the elderly. We studied a total of 31 asymptomatic healthy elderly subjects by videofluoroscopy and manometry before and after real (19 subjects) and sham (12 subjects) exercises. A significant increase was found in the magnitude of the anterior excursion of the larynx, the maximum anteroposterior diameter, and the cross-sectional area of the UES opening after the real exercise (P < 0.05). These changes were associated with a significant decrease in the hypopharyngeal intrabolus pressure studied in 12 (real-exercise) and 6 (sham-exercise) subjects (P < 0.05). A similar effect was not found in the sham-exercise group. In normal elderly subjects, deglutitive UES opening is amenable to augmentation by exercise aimed at strengthening the UES opening muscles. This augmentation is accompanied by a significant decrease in hypopharyngeal intrabolus pressure, indicating a decrease in pharyngeal outflow resistance. This approach may be helpful in some patients with dysphagia due to disorders of deglutitive UES opening.

Aged↗
PubMed1997

Blood pressure response to chronic episodic hypoxia: role of the sympathetic nervous system.

Previous studies in several strains of rats have demonstrated that 35 consecutive days of recurrent episodic hypoxia (7 h/day) cause an 8- to 13-mmHg persistent increase in diurnal systemic blood pressure (BP). Carotid chemoreceptors and the sympathetic nervous system have been shown to be necessary for development of this BP increase. The present study was undertaken to further define the role of renal artery sympathetic nerves and the adrenal medulla in this BP increase. Male Sprague-Dawley rats had either adrenal medullectomy, bilateral renal artery denervation, or sham surgery. Rats from each of these groups were subjected to episodic hypoxia for 35 days. Control groups received either compressed air or were left unhandled. Adrenal demedullation or renal artery denervation eliminated the chronic diurnal mean BP response (measured intra-arterially) to episodic hypoxia, whereas sham-operated controls continued to showed persistent elevation of systemic BP. Plasma and renal tissue catecholamine levels at the end of the experiment confirmed successful adrenal demedullation or renal denervation in the respective animals. The chronic episodic hypoxia-mediated increase in diurnal BP requires both intact renal artery nerves as well as an intact adrenal medulla.

Adrenal Medulla↗
PubMed1997

Modulation of jaw muscle spindle discharge during mastication in the rabbit.

Discharges of jaw muscle spindles were recorded during chewing carrot from mesencephalic trigeminal nucleus (Mes V) in the awake rabbit to evaluate contribution of the muscle spindles to the development of complete sequences of masticatory movements. The Mes V spindle units were divided into two types according to the maximum firing rates during mastication, with a dividing line at 200 Hz; high-frequency units and low-frequency units. Although both types of units fired maximally during the jaw-opening phase of chewing cycles, their firing rates and pattern varied according to three sequential stages of mastication (stages I, IIa, and IIb). The high-frequency units often increased firing before the start of mastication and built up firing in the first few chewing cycles. Their maximal firing rate was sometimes lower during stage IIa (chewing stage) than during stage I (ingestion stage) and stage IIb (preswallowing stage), although the jaw movements were greater in stage IIa than in other stages. The phase relationship of the firing to a jaw movement cycle in stage IIa was consistent in individual units. The low-frequency units did not build up activity before the onset of movements. They fired mostly during the jaw-opening phase, but the peak of firing did not necessarily coincide with the time of maximal opening. It was concluded that the difference in the firing pattern among masticatory stages may be ascribed to a stage-dependent modulation of both fusimotor activity and jaw movement pattern.

Animals↗
PubMed1997

Total body bone mineral density in young children: influence of head bone mineral density.

Dual-energy X-ray absorptiometry (DXA) with its short scan time, low radiation dose, and high precision and accuracy have made this technique particularly suitable for measuring total body bone mineral density (TBMD) in children. Other published reports have related TBMD to age in children 2-18 years of age. However, in young normal children aged 2-9 years (51 girls, 43 boys), we found that regression equations for TBMD with age as the predictor did not explain enough of the variance to warrant their use for predicting TBMD (adjusted R2 0.47, females; 0.41, males). Subtotal BMD (TBMD-head BMD) is predicted better by age because of a possibly invalid adult algorithm for head BMD (adjusted R2 0.73, females; 0.71, males).

Absorptiometry, Photon↗
PubMed1997

Enhancement of ovine trophoblast interferon by granulocyte macrophage-colony stimulating factor: possible involvement of protein kinase C.

Interferon-tau (oIFNtau), the major secretory product of ovine conceptuses between days 13 and 21 (day 0=day of estrus) of pregnancy, is implicated in the process of maternal recognition of pregnancy. Culturing of day-14 and day-16 conceptus tissues in the presence of human granulocyte macrophage-colony stimulating factor (hGM-CSF) or interleukin-3 (IL-3) produces a marked increase in oIFNtau mRNA and protein expression. Since GM-CSF and IL-3 are localized at the luminal and glandular epithelia of the ovine endometrium, maternally derived GM-CSF and IL-3 may affect conceptus production of oIFNtau in a paracrine manner. However, the molecular mechanisms by which endometrial GM-CSF and IL-3 up-regulate oIFNtau production have not been defined. As an initial investigation of the signaling pathway regulating the GM-CSF induction of the oIFNtau gene, day-16 conceptuses were treated with an inducer, phorbol 12-myristate 13-acetate (PMA) and an inhibitor, calphostin C of the protein kinase C (PKC) pathway. Treatment with either 150 units/ml hGM-CSF (P<0.01) or 10 nM PMA (P<0.05) resulted in a significant increase in oIFNtau mRNA expression. Pretreatment of conceptuses with 1 microM PMA for 12 h to produce PKC-deficient tissues or treatment with 50 mM calphostin C abolished the hGM-CSF-induced increase in oIFNtau mRNA. An in vitro expression system was established for the analysis of oIFNtau gene regulatory sequences. The oIFNtau010 gene has been isolated previously and found to be the principal oIFNtau gene up-regulated during the preimplantation period. 5'-Flanking regions of the oIFNtau010 gene, 2 kb and 0.8 kb, were cloned into a basic chloramphenicol acetyltransferase reporter plasmid. These oIFNtau010 promoter constructs, along with expression controls, were transfected into human choriocarcinoma cells (JAR and JEG3) and their responsiveness to hGM-CSF and second messenger system activators including PMA, calcium ionophore (A23187) and 8-bromo-cAMP were characterized. The oIFNtau010 promoter constructs were up-regulated by hGM-CSF and PMA treatments (P<0.01). Combined treatment with PMA and A23187 prevented the promoter activation seen with PMA alone. The conceptus culture data, along with the results from the transfection experiments, suggest that the stimulatory effect of GM-CSF on oIFNtau is mediated through the PKC second messenger system.

Animals↗
PubMed1997

Background subtraction in technetium-99m-MAG3 renography.

UNLABELLED: Correction represents a potential source of error in estimating split renal function and camera-based clearances. The purpose of this study was to determine which of five background options and four time intervals was associated with the least error for 99mTc-mercaptoacetyltriglycine (MAG3). METHODS: Fifteen single-kidney patients were imaged supine after 111-370 MBq (3-10 mCi) 99mTc-MAG3 injection. A phantom kidney was drawn on the 2-3-min images, approximately equal in size to the solitary kidney and used for all time intervals. Counts in the phantom and native kidneys were calculated using manual inferior and lateral regions of interest (ROIs), automated elliptical and perirenal background ROIs and no background correction at various time intervals (1-2, 1-2.5, 1.5-2.5 and 2-3 min) postinjection. With optimal background correction, counts and the relative function in the phantom kidney should be zero. The error was measuring by estimating both the relative function and absolute function expressed as the percent injected dose in the phantom kidney. RESULTS: The percent injected dose in the phantom kidney as well as the error in measuring relative function were significantly greater than zero for the inferior background correction and the no background correction options at all time intervals, p < 0.05. The percent dose in the kidney and the error associated with the lateral, elliptical and perirenal ROIs were not significantly different from zero. CONCLUSION: Regardless of time interval, the greatest error was associated with no background correction. The inferior ROI consistently underestimated the background correction and probably should not be used for 99mTc-MAG3. There was no significant difference between errors generated using the lateral and automated ROIs, although automated ROIs are probably more reproducible for sequential studies.

Adult↗
PubMed1997

Health career orientation of Oregon high school students.

BACKGROUND AND OBJECTIVES: Because a shortage of physicians for the rural United States persists, it is important to better understand why individuals from rural areas consider careers in medicine. This study assessed and compared rural and urban high school students' interest in careers in medicine. METHODS: Students attending presentations given by medical students about health care careers completed a questionnaire given at high schools between 1991-1994. This questionnaire assessed interest in health and medical careers and self-perceived capability to pursue a medical career. RESULTS: A total of 924 students attended the presentations and returned questionnaires. Approximately 33% of students expressed an interest in some type of health career. Related to choosing such a career were being female, coming from an urban area, and having had a previous talk about a health care career. Among the 13% of students considering becoming a physician, only being from an urban area or having had a previous talk were related to this choice. Rural students who had received previous talks were more likely to consider health care and medicine careers. CONCLUSIONS: Socializing rural high school students to health care and physician careers via structured talks and personal encouragement may increase the number of rural students interested in such careers and help alleviate the shortage of rural health care providers.

Adolescent↗
PubMed1997

Comparison of technetium-99m-ll-EC isomers in rats and humans.

UNLABELLED: Technetium-99m-L,L-ethylenedicysteine (99mTc-LL-EC) is a new renal imaging agent with pharmacokinetic properties reported to be slightly superior to those of 99mTc-mercaptoacetyltriglycine (99mTc-MAG3); however, to better define the potential of the enantiomer 99mTc-DD-EC and the diastereomer 99mTc-DL-EC as renal imaging agents, we compared the three EC stereoisomers with 131I-orthoiodohippurate (OIH) in a series of rats and humans. METHODS: Each 99mTc-EC stereoisomer was coinjected with OIH in six Sprague-Dawley rats for measurements of clearance and extraction fraction. Each stereoisomer was also coinjected with OIH in three human volunteers followed by sequential imaging, plasma clearance measurements and timed urine collections. RESULTS: Technetium-99m-DD-EC had the highest clearance and extraction efficiency in rats (p < or = 0.02). In humans, image quality was good with all three agents. The clearance ratio (EC/OIH) was 82% +/- 8% for 99mTc-DD-EC compared to 70% +/- 3% and 40% +/- 5% for 99mTc-LL-EC and 99mTc-DL-EC, respectively. Technetium-99m-DD and 99mTc-LL-EC were excreted more rapidly than 99mTc-DL-EC. CONCLUSION: Technetium-99m-DD-EC has excellent imaging properties and the data suggest that its clearance may approach that of OIH more closely than any other 99mTc renal agent. A potential limitation is the fact that both 99mTc-DD and LL-EC exist in dianionic (80%) and monoanionic (20%) forms at physiological pH and it is unlikely that these two forms have the same clearance or protein binding affinity.

Animals↗
PubMed1997

Factors affecting the use of folic acid supplements in pregnant women in Glasgow.

BACKGROUND: Use of folic acid supplements preconception, and during the first trimester, is associated with a reduced incidence of first and subsequent neural tube defects. The Department of Health guidelines recommend the use of folic acid supplements by all women planning a pregnancy. AIM: To ascertain the proportion using folic acid supplements and the factors affecting their use. METHOD: Questionnaires were distributed postpartum to the 515 women who delivered normal babies in three maternity units in Glasgow over a four-week period. RESULTS: Forms were completed by 487 (95%) women. Only 57% took supplements at some point during their pregnancy, and only 21% took them before conception. Failure to take supplements was significantly associated with unplanned pregnancy, younger age, and previous pregnancies. Lack of awareness of the potential benefits associated with folic acid use was the commonest reason cited by women for not taking supplements. CONCLUSIONS: Increased health education through health care professionals and mass media campaigns can improve awareness and thereby increase the use of supplements in planned pregnancies. However, 42% of women in our study had unplanned pregnancies. Intake of folic acid supplements in this group can only be increased by improvements in dietary intake within the population as a whole, and by fortification of commonly ingested foods.

Female↗
PubMed1996

Effects of calorie restriction and aging on the expression of antioxidant enzymes and ubiquitin in the liver of Emory mice.

We studied the effect of age and calorie restriction on the expression of genes involved in antioxidant defenses in livers of young (4.5-6 months) and old (22 months) Emory mice fed a control (C) or restricted (R) diet. Specifically examined were catalase (CAT), glutathione peroxidase (Gpx), Cu/Zn and Mn superoxide dismutase (Cu/ZnSOD and MnSOD). As an indicator of oxidative damage to the tissues we measured lipid peroxidation. As indicators of oxidative stress we determined ubiquitin mRNA levels and endogenous high molecular weight (HMW) ubiquitin conjugates. Lower mRNA levels of ubiquitin (P < 0.05), CAT (P < 0.01) and Gpx (P < 0.01) were observed in tissues from young R versus C animals. The old C group had a lower CAT mRNA level (P < 0.0001) compared with young C. In the R group, age did not affect the CAT mRNA levels or Gpx mRNA levels; however, ubiquitin mRNA levels were higher (P < 0.05). No significant changes in Cu/Zn or MnSOD mRNA were observed with age or diet. Cu/ZnSOD protein levels were lower in the young R at 4.5 months (P < 0.05) than young C, and higher in the old R group versus old C (P < 0.05). CAT protein levels were higher in the old C versus old R (P < 0.05). Changes of HMW ubiquitin conjugates with age r diet were not significant. Of the four groups, the old R group showed the highest levels of lipid peroxidation.

Aging↗
PubMed1996

Ubiquitinylation and ubiquitin-dependent proteolysis in vertebrate photoreceptors (rod outer segments). Evidence for ubiquitinylation of Gt and rhodopsin.

In corroboration of the hypothesized regulation of phototransduction proteins by the ubiquitin-dependent pathway, we identified free ubiquitin (8 kDa) and ubiquitin-protein conjugates (50 to >200 kDa; pI 5.3-6.8 by two-dimensional electrophoresis) in bovine rod outer segments (ROS). A 38-kDa ubiquitinylated protein and transducin (Gt) were eluted together from light-adapted ROS membranes with GTP. When ROS were dark-adapted, this 38-kDa ubiquitinylated species and Gt were readily solubilized in buffer lacking GTP. These data are consistent with ubiquitinylation of Gt and corroborate previous cell-free experiments identifying Gt as a substrate for ubiquitin-dependent proteolysis (Obin, M. S., Nowell, T., and Taylor, A. (1994) Biochem. Biophys. Res. Commun. 200, 1169-1176). Evidence for ubiquitinylation of rhodopsin (36 kDa), the (photo)receptor coupled to Gt, included (i) the presence in ROS membranes "stripped" of peripheral membrane proteins of numerous ubiquitin-protein conjugates, including two whose masses (44 and 50 kDa) are consistent with mono- and diubiquitinylated rhodopsin; (ii) catalysis by permeabilized ROS of 125I-labeled ubiquitin-protein conjugates whose masses (42, 50, and 58 kDa) suggest a "ladder" of mono-, di-, and triubiquitinylated rhodopsin; (iii) parallel mobility shifts on SDS-polyacrylamide gels of rhodopsin and these 125I-labeled ubiquitin-protein conjugates; and (iv) generation of enhanced levels of 125I-labeled ubiquitin-protein conjugates when stripped, detergent-solubilized ROS membranes (95% rhodopsin) were incubated with reticulocyte lysate. A functional ubiquitin-dependent pathway in ROS is demonstrated by the presence of (i) the ubiquitin-activating enzyme (E1); (ii) four ubiquitin carrier proteins (E214K, E220K, E225K, and E235K) and pronounced activity of E214K, an enzyme required for "N-end rule" proteolysis; (iii) ATP-dependent 26 S proteasome activity that rapidly degrades high mass 125I-labeled ubiquitin-ROS protein conjugates; and (iv) distinct ubiquitin C-terminal isopeptidase/hydrolase activities, including potent ubiquitin-aldehyde-insensitive activity directed at high mass ubiquitinylated moieties. Considered together, the data support a novel role for the ubiquitin-dependent pathway in the regulation of mammalian phototransduction protein levels and/or activities and provide the first identification of a non-calpain proteolytic system in photoreceptors.

Animals↗