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Biomedical subjects

L Turner

Publications and source records attributed to L Turner.

At least 73 records · Page 4Linked to original sources
PubMed1997

A sheep named Dolly.

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Animal Experimentation↗
PubMed1997

Genomic organization of the mouse fertilin beta gene that encodes an ADAM family protein active in sperm-egg fusion.

The fertilin alpha and beta genes (Ftna and Ftnb, respectively) encode a sperm surface heterodimer that functions in sperm-egg fusion. They are the first identified members of a large gene family coding for multidomain membrane proteins (ADAMs) that include A Disintegrin And Metalloprotease domain. In this study, we report the isolation and structural organization of the mouse fertilin beta gene. The gene is present as a single copy and covers a region of approximately 55 kilobases in the genome. The fertilin beta gene is composed of at least 20 exons interrupted by 19 introns. The sizes of the exons are relatively small and vary from 56 to 193 bases; the sizes of introns vary from 350 bases to 9.4 kilobases. The exon-intron boundaries conform to the GT/AG rule with one exception: GC replaces GT at the 5' splice site in intron 13. Comparison of genomic organization between mouse fertilin beta and the previously sequenced ADAM family gene, human MDC [Katagiri et al. (1995): Cytogenet Cell Genet 68:39-44] showed 12 conserved exon-intron boundaries. In addition, we analyzed the fertilin alpha gene, demonstrating that more than one gene is present in the mouse genome.

ADAM Proteins↗
PubMed1997

Purification and identification of apophycocyanin alpha and beta subunits from soluble protein extracts of the red alga Cyanidium caldarium. Light exposure is not a prerequisite for biosynthesis of the protein moiety of this photosynthetic accessory pigment.

Much controversy exists as to the level at which light exerts control over the biosynthesis of the photosynthetic apparatus in higher plants and other organisms. The eukaryotic red alga Cyanidium caldarium, like higher plants, undergoes light induction of chlorophyll synthesis. In addition to chlorophyll a the alga also synthesises the linear tetrapyrrole phycocyanobilin, which is combined with alpha or beta apobiliproteins to form phycocyanin, the major light-harvesting pigment in this organism. We have previously shown that the tetrapyrrole precursor 5-aminolaevulinic acid (ALA) can substitute for light in inducing the biosynthesis of the phycocyanobilin moiety of this protein. We have also described the appearance of a protein of similar isoelectric point and molecular weight to phycocyanin in ALA-fed cells (Turner et al., 1992, Plant Physiol Biochem 30: 309-314). We now report on the protein's immunological and sequence identity with phycocyanin alpha and beta subunits, and provide further evidence that bilin-apoprotein ligation is light dependent.

Amino Acid Sequence↗
PubMed1997

Mixed Candida glabrata and Candida albicans disseminated candidiasis in a heroin addict.

The case of a white-heroin addict who developed disseminated candidiasis following coinfection by Candida glabrata and Candida albicans is reported. Genomic random amplified polymorphic DNA typing suggested that the Candida glabrata blood isolates originated in the oral cavity of the patient. This case strengthens the evidence that Candida species other than Candida albicans can be involved in the pathogenesis of disseminated candidiasis in heroin addicts.

AIDS-Related Opportunistic Infections↗
PubMed1997

Arterial reactivity is enhanced in genetic males taking high dose estrogens.

OBJECTIVES: We sought to assess whether high dose estrogen treatment is associated with enhanced arterial reactivity in genetic males. BACKGROUND: Although estrogens have been shown to enhance arterial reactivity in women, and are thereby thought to confer cardiovascular benefit, the vascular effects of long-term estrogen therapy in genetic males is unknown. METHODS: We studied the arterial physiology of 30 genetic males--15 male to female transsexuals receiving long-term high dose estrogen therapy and 15 healthy male control subjects matched for age, smoking history and vessel size. Using external vascular ultrasound, brachial artery diameter was measured at rest, after flow increase (causing endothelium-dependent dilation [EDD]) and after nitroglycerin (GTN), an endothelium-independent dilator. Blood pressure, cholesterol and testosterone levels were also measured in each subject. RESULTS: Total testosterone and free testosterone index levels were lower in the transsexuals compared with the control subjects (p < 0.001). In contrast, EDD was significantly higher in the transsexuals than in the control males (mean [+/-SD] 7.1 +/- 3.1% vs. 3.2 +/- 2.8%, p = 0.001), as was the GTN response (21.2 +/- 6.7% vs. 14.6 +/- 3.3%, p = 0.002). Total and high density lipoprotein cholesterol, blood pressure levels and baseline vessel size were similar in the two groups. On multivariate analysis, enhanced EDD was associated independently with estrogen therapy (p = 0.02) and with low total cholesterol (p = 0.04). An enhanced GTN response was also significantly associated with estrogen therapy (p = 0.03). CONCLUSIONS: Long-term treatment with high dose estrogens is associated with enhanced arterial reactivity in genetic males, which may be due to the effects of estrogen excess or androgen deprivation, or both.

Adult↗
PubMed1997

An analysis of testosterone implants for androgen replacement therapy.

OBJECTIVE: To review 13 years of experience using fused crystalline testosterone implants for androgen replacement therapy in order to identify pattern of usage (including continuation rates) and adverse events emerging during therapy and factors associated with adverse events including implant extrusions. DESIGN: Retrospective review of prospectively collected data on characteristics of patients and implant procedures performed as well as adverse events reported during routine follow-up. PATIENTS: Over 13 years 973 implant procedures using fused crystalline testosterone implants were performed in 221 men. MEASUREMENTS: Continuation rates and adverse events such as extrusions, bleeding, infection or others were recorded and analysed in relationship to characteristics of the patient and the implant procedure performed. RESULTS: Overall rate of adverse events (108/73, 11.1%) was significantly related to increased numbers of implants (4.2 +/- 0.1 vs 4.0 +/- 0.03, P = 0.031) and higher levels of physical activity at work (P = 0.030). The most common adverse effect was extrusion (83/973, 8.5%) which was related to occupational classification (P = 0.033) and increasing work activity (P = 0.044) and occurred more frequently than by chance in multiple (16 vs 3.3 expected) rather than single (65 vs 76.1 expected) episodes. Bleeding (22/973, 2.3%) was significantly associated with an increased number of implants (4.5 +/- 0.2 vs 4.0 +/- 0.03, P = 0.020) but even in the worst cases (3/22) it was of minor clinical importance. Infection was rare (6/973, 0.6%) but occurred more among thinner men. The overall continuation rate was 92.7% increasing from 86% after the first implantation to > 99% after the tenth implant. CONCLUSIONS: This study demonstrates the very satisfactory clinical acceptability of testosterone pellet implants for androgen replacement therapy within a single unit with experienced operators. The only regular adverse effect is extrusion, which may be related to mechanical factors such as habitual work activity but also possibly procedural factors. Other adverse effects such as bleeding, infection and fibrosis were rare. An improved method of implant delivery would enhance this old but durable technology.

Adult↗
PubMed1997

Social influence on southern adolescents' smoking transition: a retrospective study.

The purpose of this study was to examine social factors that predicted adolescent smoking transition to more advanced stages of smoking behavior during a 3-year span. A national cohort sample of adolescents (N = 2,099) who participated in the 1989 and 1993 Teenage Attitudes and Practices Survey (TAPS I and TAPS II, respectively) was used for this study. The information obtained from this survey included measurements of smoking behavior and a series of factors related to smoking models in the respondents' social environment, such as smoking behavior of parents, siblings, and best friends. Results showed that the smoking behavior of an adolescent's best male friend was consistently associated with transition from nonsmoking to regular smoking and from experimental smoking to regular smoking. The most surprising finding was that the study showed no relationship between social influence and transition from nonsmoking to experimental smoking.

Adolescent↗
PubMed1997

Implementing a hospital-wide pain management strategy.

The purpose of this article is to describe the process of undertaking a large scale nursing pain management initiative, that we entitled "Pain Month." Several educational resources and strategies were employed in an effort to increase nurse's knowledge on the subject of pain management. Pre and post patient satisfaction surveys were conducted to test the effect of the education on actual pain management. The results showed improvements in actual pain scores and in satisfaction with pain management; however, several more improvements were shown to be necessary to achieve excellent pain management for patients. Follow-up initiatives such as a pain resource nurse program, an interdisciplinary pain committee and continued, patient surveys have been implemented to address some of these existing issues.

Analgesics↗
PubMed1996

[Yersinia enterocolitica: a cause of acute intestinal intussusception].

OBJECTIVES: Yersinia enterocolitica infection is a rare cause of intestinal intussusception, especially in adults. We report here a case in a 29-year-old man and review the literature on diagnosis and therapy. CASE REPORT: A 29-year-old man presented with a 2-week history of diarrhea and weight loss. Ultrasonography revealed acute intestinal intussusception localized at the site of enlarged mesenteric nodes. At laparostomy, intestinal resection was not required. Histology examination of the mesenteric nodes showed follicular hyperplasia. Serology was positive for Yersinia enterocolitica. Outcome was favorable after treatment with tetracycline for 15 days. DISCUSSION: Yersinia enterocolitica are Gram negative bacilli that grow at low temperature. Food contamination is the most frequent source of infection in man, usually in children. Clinical manifestations include gastroenteritis or pseudoappendicular syndrome. Intestinal intussusception is rare. Operative reduction by taxis is generally sufficient. Histology examination of the lymph nodes excludes lymphoma. The diagnosis is confirmed by serology. A 10 to 15-day antibiotic regimen is needed.

Acute Disease↗
PubMed1996

Nucleus accumbens dopamine depletions alter relative response allocation in a T-maze cost/benefit task.

This experiment was conducted to study the role of nucleus accumbens dopamine in the performance of a novel T-maze cost/benefit procedure. Rats were trained on a T-maze task for food reinforcement. Under one of the test conditions, one arm of the maze contained a high reinforcement density (4 x 45 mg Bioserve pellets) and the other arm contained a low reinforcement density (2 x 45 mg pellets). A large vertical barrier (44 cm) was placed in the arm that contained the high density of food reinforcement. In the second test condition, a separate group of rats was trained in the same T-maze, in which there were 4 food pellets in the arm that was obstructed by the barrier, yet there were no food pellets in the unobstructed arm. After training rats received intra-accumbens of injections 6-hydroxydopamine or ascorbate vehicle. Nucleus accumbens dopamine depletions substantially decreased the number of selections of the obstructed arm with the high reinforcement density when the unobstructed arm also contained 2 food pellets. Dopamine-depleted rats in this condition showed increased selection of the no-barrier arm as well as decreased entry into the arm that contained the barrier. These effects persisted throughout the 3 weeks of post-surgical testing. Nevertheless, when the unobstructed arm contained no food pellets, and the only way to obtain food was to climb the barrier, rats with nucleus accumbens dopamine depletions showed only a modest effect on selections of the obstructed arm, which recovered by the second week of testing. Dopamine-depleted rats that were tested with food in the unobstructed arm showed significantly fewer barrier crossings than dopamine-depleted rats that were tested with no food in the unobstructed arm. Thus, the present findings are not consistent with the notion that nucleus accumbens dopamine depletion rendered the animals unable to climb the barrier, or set an absolute ceiling on the number of barrier crossings the animals could perform. Instead, the present results indicate that nucleus accumbens dopamine depletions affected the relative allocation of barrier climbing responses if alternative food sources were available.

Animals↗
PubMed1996

Temperature-induced switching of the bacterial flagellar motor.

Chemotaxis signaling proteins normally control the direction of rotation of the flagellar motor of Escherichia coli. In their absence, a wild-type motor spins exclusively counterclockwise. Although the signaling pathway is well defined, relatively little is known about switching, the mechanism that enables the motor to change direction. We found that switching occurs in the absence of signaling proteins when cells are cooled to temperatures below about 10 degrees C. The forward rate constant (for counterclockwise to clockwise, CCW to CW, switching) increases and the reverse rate constant (for CW to CCW switching) decreases as the temperature is lowered. At about -2 degrees C, most motors spin exclusively CW. At temperatures for which reversals are frequent enough to generate a sizable data set, both CCW and CW interval distributions appear to be exponential. From the rate constants we computed equilibrium constants and standard free energy changes, and from the temperature dependence of the standard free energy changes we determined standard enthalpy and entropy changes. Using transition-state theory, we also calculated the activation free energy, enthalpy, and entropy. We conclude that the CW state is preferred at very low temperatures and that it is relatively more highly bonded and restricted than the CCW state.

Bacterial Adhesion↗