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Biomedical subjects

A T Miller

Publications and source records attributed to A T Miller.

At least 19 recordsLinked to original sources
PubMed1999

Quantitation of urinary metabolites of a tobacco-specific lung carcinogen after smoking cessation.

We quantified urinary levels of two metabolites of the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in people who had stopped smoking: 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its O-glucuronide, 4-[(methylnitrosamino)-1-(3-pyridyl)but-1-yl]-beta-O-D-glucosiduronic acid (NNAL-Gluc). Twenty-seven people completed the study. Thirteen used the nicotine patch starting at the quit date, whereas the others used no patch. Two 24-h urine samples were collected on 2 consecutive days before smoking cessation; blood was also obtained. Beginning at their quit date, subjects provided 24-h urine samples on days 7, 21, 42, 70, 98, and 126, and some subjects also provided samples at later times. The urine was analyzed for NNAL, NNAL-Gluc, nicotine plus nicotine-N-glucuronide, and cotinine plus cotinine-N-glucuronide. Some blood samples were also analyzed for NNAL. The decline of urinary NNAL and NNAL-Gluc after smoking cessation was much slower than expected. This was clearly demonstrated by comparison with cotinine and nicotine levels in urine. One week after smoking cessation, 34.5% of baseline NNAL plus NNAL-Gluc was detected in urine, whereas the corresponding values for cotinine and nicotine were 1.1 and 0.5%, respectively. Even 6 weeks after cessation, 7.6% of the original levels of NNAL plus NNAL-Gluc remained. In some subjects, NNAL plus NNAL-Gluc were detected 281 days after cessation. The distribution half-life for NNAL and NNAL-Gluc was 3-4 days, whereas the elimination half-life was 40-45 days. Total body clearance of NNAL was estimated to be 61.4 +/- 35.4 ml/min, and volume of distribution in the beta-phase was estimated to be 3800 +/- 2100 liters, indicating substantial distribution into the tissues. Parallel studies in rats treated chronically or acutely with NNK in the drinking water support the conclusion that NNAL has a large volume of distribution. There was no effect of the nicotine patch on levels of NNAL plus NNAL-Gluc, indicating that NNK is not formed endogenously from nicotine. The results of this study demonstrate that NNAL and NNAL-Gluc are slowly cleared from the body after smoking cessation, indicating the presence of a high-affinity compartment where NNK, NNAL, and/or NNAL-Gluc are retained or sequestered and slowly released.

Adult↗
PubMed1999

Suppression of ovarian activity in the gilt and reversal by exogenous gonadotrophin administration.

The aim of the current experiment was to study the regulation of follicle development in the pig using a potent GnRH agonist (GnRH-A) to initially suppress follicle development. Large-White hybrid gilts (n = 8) were treated during the luteal phase with GnRH-A. Four of these GnRH-A treated gilts and four control gilts were given a GnRH bolus on days 14 and 28 after GnRH-A administration or during the luteal phase in control gilts. Blood samples were collected for 10 h for FSH and LH, after which 1500 IU PMSG were administered and the ovaries and uteri recovered 72 h later. A further four GnRH-A treated gilts and four control gilts were slaughtered either 28 days after GnRH-A administration or during the luteal phase respectively, and all follicles > or = 1 mm diameter were dissected. The mean basal plasma FSH level was lower (P < 0.01) in GnRH-A treated than control gilts and showed no response to the GnRH challenge although levels increased (P < 0.01) in control gilts. The mean basal plasma LH levels were similar (P > 0.1) in GnRH-A treated and control gilts. Whilst in GnRH-A treated gilts plasma LH levels showed no response to the GnRH challenge, plasma LH levels were increased (P < 0.01) in control gilts. Pulsatile LH secretion was abolished in GnRH-A treated but not in control gilts. Plasma oestradiol levels were lower (P < 0.001) in GnRH-A treated gilts than in control gilts, but nevertheless both GnRH-A treated and control gilts responded to PMSG with increased plasma oestradiol levels. Treatment with GnRH-A reduced both the mean (2.1 vs. 2.7 mm; P < 0.01) and the maximal follicle diameter (4 vs. 6 mm) and reduced (P < 0.01) the total number of follicles > or = 2 mm diameter compared with control gilts. Administration of PMSG increased both mean follicle diameter (5.1 vs. 4.4 mm; P < 0.01) and maximal follicle diameter (7 vs. 9 mm) and caused a reduction (P < 0.001) in the total number of follicles > or = 2 mm diameter in both GnRH-A treated and control gilts. In summary, this study has demonstrated, for the first time in the pig, that the inhibition of follicle development as a result of pituitary down regulation/desensitisation can be reversed by exogenous gonadotrophin treatment. This model will be a powerful tool with which to investigate the precise regulation of follicle development in the pig.

Animals↗
PubMed1999

Effect of FSH infusion on follicle development in GnRH agonist-treated gilts.

The aim was to investigate the effect of infusion of purified FSH alone on follicle development in hypogonadotrophic GnRH agonist-treated gilts. Large-White hybrid gilts (n = 12) were treated during the mid-luteal phase and again after 28 days (day 0) with a potent slow releasing GnRH agonist. On day 3, seven gilts were infused for 168 h with 1.5 S1 units oFSH h-1 (equivalent to 1.5 units of bioactivity of NIH-FSH-S1 standard) and blood samples were collected. Ovaries were then recovered and all follicles > or = 1 mm in diameter were dissected and incubated for 2 h in 1 ml Eagle's minimum essential medium. The ovaries were recovered from the remaining five GnRH agonist-treated gilts on day 10 and also from five cyclic gilts during the late follicular phase (controls). Plasma FSH concentrations in GnRH agonist-treated gilts were lower (P < 0.01) than in follicular phase controls, increased (P < 0.001) after 1 h of FSH infusion and reached a plateau similar (P > 0.1) to that of controls after 8 h. Basal LH concentrations were similar (P > 0.1) between GnRH agonist-treated and control gilts and remained unchanged (P > 0.1) throughout the infusion period. GnRH agonist treatment reduced (P < 0.01) basal oestradiol concentrations compared with control gilts. Infusion with FSH alone increased (P < 0.001) plasma oestradiol concentrations after 96 h compared with those before infusion; when the animals were killed oestradiol concentrations were higher (P < 0.01) in GnRH agonist-treated gilts infused with FSH than in controls. This was also apparent by vulval swelling and behavioural oestrus. There were more follicles > or 1 mm in diameter in the GnRH agonist-treated groups than in the controls (184, 153 and 86 per animal; P < 0.01). Infusion with FSH increased the maximum follicle diameter (GnRH agonist: < 4 mm; FSH infused: < 12 mm; controls: < 10 mm) and tended to increase (P < 0.07) the mean number of follicles > or = 6 mm diameter per animal (FSH infused: 53; controls: 21). Total oestradiol production in vitro by follicles > or = 1 mm was higher (P < 0.01) in GnRH agonist-treated gilts infused with FSH and in follicular phase controls than in animals treated with GnRH agonist alone. However, oestradiol and testosterone secretion in vitro per follicle > or = 6 mm in diameter was lower (P < 0.05) in FSH-infused animals than in controls. In summary, although infusion of FSH alone stimulated the growth of multiple follicles of preovulatory size in GnRH agonist-treated gilts, steroidogenic output by individual follicles was impaired.

Analysis of Variance↗
PubMed1998

Child fosterage in the United States: signs of an African heritage.

"The presence of significant numbers of family and household structures among African Americans...[differs] from traditional Euro-American models.... The recently developed U.S. Census public use samples and measures oriented to the practices of informal child fosterage are used to examine and compare these different bases of family life. Data from the turn of the century provide some historical distance from previous explanations of difference centered on slavery, or explanations that focus on contemporary social issues such as urban problems or the welfare state. Comparisons with studies of the contemporary U.S., Africa, the Caribbean, and historical materials give broader scope to fosterage analysis and to the consideration of cultural family differences."

Black or African American↗
PubMed1998

Follicle dynamics and aromatase activity in high-ovulating Meishan sows and in Large-White hybrid contemporaries.

This study compared the dynamics of follicle development during the follicular phase in Meishan sows (n = 10) with a high ovulation rate, with those in contemporary Large-White hybrid sows (n = 12) (ovulation rates: 27.7 and 17.6, respectively; p < 0.01). Ovaries were recovered on Day 16 or 19 of the cycle, and all follicles > or = 1 mm in diameter were dissected. Fluid was aspirated from all those > or = 2 mm, and the granulosa and theca cells were incubated to estimate aromatase activity and estradiol production. The total number of follicles dissected was higher in Meishan than in Large-White hybrid animals (p < 0.001), and whereas the number decreased (p < 0.01) between Days 16 and 19 in Large-White hybrid sows, there was no significant change in Meishan animals. The mean diameter of Meishan follicles recovered on each of Days 16 and 19 was smaller (p < 0.001) than that of those recovered from Large-White hybrids. Total estradiol production in vitro was higher (p < 0.01) by follicles > or = 2 mm from Meishan sows. There was an interaction (p < 0.01) between day of the cycle, breed, and follicle diameter in aromatase activity in both granulosa cells and theca tissue, and in follicular fluid estradiol concentrations in follicles > or = 2-< 6 mm. The largest three size categories of follicles recovered on Day 19 from each breed were classified as preovulatory (29.0 and 17.7 for Meishan and Large-White hybrid, respectively), and the mean diameter was smaller (p < 0.001) in Meishan animals. Follicular fluid estradiol concentrations and total estradiol synthesis by granulosa and theca combined were higher (p < 0.05) in Meishan than in Large-White hybrid sows. In conclusion, high-ovulating Meishans maintained a higher number of follicles during the follicular phase, which overall synthesized more estradiol in vitro, than did Large-White hybrid animals.

Animals↗
PubMed1990

Patterns of runaway behavior within a larger systems context: the road to empowerment.

Runaway behavior is a common problem in residential treatment settings for youth. This paper looked at Orten and Soll's runaway typology and Homer's conceptualization of runaways as "running from" or "running to" something and expanded the context to include interactions with family and professionals. A case study and a survey of nine adolescent runaways from a residential setting were used to explore several hypotheses. A discussion of the results and practical applications illustrated ways to empower therapists and other professionals to deal with runaways more effectively.

Adolescent↗
PubMed1989

Biological effects of galactic radiation HZE particles in experiments on the orbital station Salyut 7.

Lettuce (Lactuca sativa) seeds were flown on-board the orbital station Salyut 7 for 66-457 days. It was found that a single heavy charged particle (HZE) hitting a seed only slightly affects the subsequent plant growth. However, morphological anomalies of varying type in primordial leaves and roots were observed that show good correlation with the location of the particle track. The most severe damage detected by light and an electron microscopy were "channels" in dry and soaked seeds. The appearance of "channels" seems to be related to the LET of the incident particle. This finding is of considerable importance for assessment of space flight radiation hazard.

Cosmic Radiation↗
PubMed1983

Results on Artemia cysts, lettuce and tobacco seeds in the Biobloc 4 experiment flown aboard the Soviet Biosatellite Cosmos 1129.

Artemia cysts, lettuce and tobacco seeds were flown aboard the Cosmos 1129 for 19 days. A correlative method was used in order to determine the passage of cosmic heavy ions (HZE particles) through the biological test objects. This space flight resulted in a decrease on hatchability, nucleic acid and protein synthesis in hydrated Artemia cysts. HZE particle effects on plant cellular chromosomes are confirmed. In tobacco seeds, a stimulating effect on germination rate and a higher frequency of abnormalities were observed. Dormant biological objects are a very suitable material to study cosmic ray effects: these objects can be arranged in monolayers and sandwiched between visual track detectors in order to determine the passage of the cosmic heavy ions (HZE particles). On the other hand this method allows us to study effects of microgravity and those of the protonic component of cosmic rays in the objects not hit by the HZE articles.

Animals↗
PubMed1978

Restitution of ATP and creatine phosphate after experimental depletion in young, adult, and old rats.

The rates of restitution of skeletal muscle, heart, and brain creatine phosphate and brain ATP, following experimental depletion, were compared in young (3-5 month), adult (12 month) and old (24 month) rats. In skeletal muscle, restitution of creatine phosphate after 3 min of recovery was greatest in the young rats, minimal in the adult animals, and absent in the old animals. In heart muscle, on the other hand, restitution was rapid in all three age groups, and was essentially complete after 60 sec recovery. In brain, restitution of creatine phosphate was rapid and was complete after 10 min recovery in the young and adult rats; restitution was slower and less complete in the old rats. In the old rats there was no restitution of brain ATP during the first 2 min of recovery, after which the rate of restitution paralleled that of the young and adult rats.

Adenosine Triphosphate↗
PubMed1977

Age related changes in the effect of electroconvulsive shock (ECS) on the in vivo hydroxylation of tyrosine and tryptophan in rat brain.

A single electroconvulsive shock (ECS) was applied to 40 young (9 months) and 40 old (24 months) male rats. The effect on brain catecholamine synthesis was determined at intervals after ECS by measuring the accumulation of dihydroxyphenylalamine (DOPA) and 5-hydroxytryptophan (5-HTP) in rats pretreated with a central decarboxylase inhibitor (M-hydroxybenzyl hydrazine, NSD 1015). This accumulation permitted an estimation of the in vivo rates of hydroxylation of tyrosine and tryptophan. Control brain DOPA and 5-HTP concentrations were both lower in the older animals. Following ECS there was an increase in brain DOPA concentration (maximal at 60 min after ECS) in both young and old rats, but the increase was much smaller in the older animals. There were no changes in brain 5-HTP at any time after ECS, in either age group. It appears that aging selectively affects the response of the brain dopaminergic neurotransmitter system to stress, and we suggest that this may be a factor in the decreased resistance to stress in older subjects.

5-Hydroxytryptophan↗
PubMed1977

Active and passive avoidance in rats as a function of age.

Rats of four age groups: young (30 days of age), adolescent (180 days of age), adult (365 days of age), and old (547 days of age) were trained on active and passive avoidance tasks. There was impaired acquisition and 30-day rentention of passive-avoidance learning in both young and old rats, compared to the intermediate age groups, and marked impairment of acquisition and retention of active-avoidance learning in the old rats. Learning impairment is thus associated with immaturity as well as senescence.

Aging↗
PubMed1977

Effect of weightlessness and of artificial gravity on irradiated lettuce seeds.

In our previous studies on board the artificial earth satellite Cosmos 368, the cosmic apparatus Zond 8 and the orbital station Salyut it has been demonstrated that space-flight factors (SFF) have a definite effect on poorly active biological systems, such as dry lettuce seeds. The technical possibilities on board the biosatellite Cosmos 782 (the availability of an on-board centrifuge) allowed us to obtain some new data concerning the mechanisms of the SFF effects. Irradiated seeds of lettuce (Lactuca sativa L.) were exposed in space flight for 22 days either to weightlessness conditions only or to a centrifugal field. Data have been obtained characterizing the cytogenetical and physiological processes in seeds of various series of the experiment. An attempt is made to analyse the role of individual SFF in the changes observed.

Centrifugation↗