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Biomedical subjects

L Buck

Publications and source records attributed to L Buck.

At least 19 recordsLinked to original sources
PubMed2005

One stop fertility clinic.

UNLABELLED: The objective of this study was to determine the feasibility and acceptability of out-patient based investigation of infertile couples using a prospective observational study based in a large undergraduate teaching hospital. We studied couples referred to secondary care for investigation of their infertility. Investigations involved pelvic ultrasound, diagnostic hysteroscopy and culdoscopy. The main outcome measures were feasibility of investigations, findings, patient views, and a management plan. RESULTS: 199 of 347 (57.3%) couples referred met our selection criteria, and 162 of this group have attended. Thirty-one (19.1%) were judged to be unsuitable for culdoscopy, and culdoscopy failed in a further 29 (17.9%). The average time for the three procedures was 41.2 (SD 17.2) minutes, and over 1/3 of patients were found to have pelvic pathology. The investigations were well tolerated and there was only one complication necessitating admission to hospital. Most patients appreciated the need for a single hospital visit and the availability of immediate results. CONCLUSIONS: A One Stop approach to the investigation of infertility is attractive but not suitable for or desired by all infertile couples. Organisational issues were also identified.

Adult↗
PubMed2005

Outpatient hysteroscopy: traditional versus the 'no-touch' technique.

OBJECTIVE: To assess whether outpatient hysteroscopy using the 'no-touch' technique confers any advantages in terms of patient discomfort over the traditional technique. DESIGN: Prospective randomised controlled study. SETTING: Outpatient hysteroscopy clinic in a large university undergraduate teaching hospital. POPULATION: All women referred for outpatient hysteroscopy in a 12-month period. INTERVENTIONS: Women were randomised to undergo either traditional saline hysteroscopy requiring the use of a speculum and tenaculum, or a 'no-touch' vaginoscopic hysteroscopy which does not require a speculum or tenaculum. Each group was further subdivided to have hysteroscopy with either a 2.9-mm or 4-mm hysteroscope. Patients were asked to complete pre- and postprocedure questionnaires ranking pain scores. MAIN OUTCOME MEASURES: The relative success of each of these techniques, requirement for local anaesthetic and pain scores at different times during the hysteroscopy were recorded at the end of the procedure. The time taken to carry out each procedure was also measured. RESULTS: One hundred and twenty women were recruited in this study: 60 were randomised to traditional hysteroscopy and 60 to 'no-touch' hysteroscopy. The overall success rate for hysteroscopy was 99%. There was no significant difference in the requirement for local anaesthetic between the two groups, but those who underwent 'no-touch' hysteroscopy with a 2.9-mm hysteroscope had the lowest requirement of local anaesthetic (10% compared with 27% in the no-touch hysteroscopy with a 4-mm hysteroscope group). The time taken to perform hysteroscopy and biopsy was significantly shorter with 'no-touch' hysteroscopy (5.9 vs 7.8 min; difference 1.9, 95% CI 0.7-3.1). There were no differences in pain scores between the groups at different times during hysteroscopy. CONCLUSIONS: 'No-touch' or vaginoscopic hysteroscopy is significantly faster to perform than the traditional technique. Although there was no difference in pain scores between the two techniques, local anaesthetic requirements were least in those who underwent 'no-touch' hysteroscopy with a narrow bore hysteroscope.

Adult↗
PubMed2001

Biodegradation potential of photocatalyzed surfactant washwater.

Enhanced release of hydrophobic compounds from a soil matrix can be achieved by use of soil-washing or soil-flushing using various surfactants. However, the surfactants used in achieving the desorption of organic contaminants may also cause a problem in subsequent removal/disposal of these contaminants. UV radiation in the presence of TiO2 as a pre-treatment step to achieve initial (or partial) breakdown of naphthalene and Sodium Dodecyl Sulfate (SDS) using batch experiments indicated that 56% to 88% naphthalene degradation occurred within 30 minutes to one hour. Preliminary results on the estimate of the batch aerobic biodegradation potential of photocatalyzed washwater containing naphthalene and SDS suggested that SDS was the major carbon and energy source for an activated sludge enrichment culture and an enrichment culture obtained from microorganisms at a contaminated site. Continuous-flow stirred tank reactors (CSTRs) with with a solids retention time (SRT) of 4 days were not effective, but an SRT of 8 days was successful in biodegrading the naphthalene and surfactant. These results indicated that photocatalytic treatment as a pre-treatment step followed by a biodegradation step may offer potential in cleaning up surfactant washwaters containing organic contaminants.

Bacteria, Aerobic↗
PubMed1998

Reversible decreases in ATP and PCr concentrations in anoxic turtle brain.

A hallmark of anoxia tolerance in western painted turtles is relative constancy of tissue adenylate concentrations during periods of oxygen limitation. During anoxia heart and brain intracellular compartments become more acidic and cellular energy demands are met by anaerobic glycolysis. Because changes in adenylates and pH during anoxic stress could represent important signals triggering metabolic and ion channel down-regulation we measured PCr, ATP and intracellular pH in turtle brain sheets throughout a 3-h anoxic-re-oxygenation transition with 31P NMR. Within 30 min of anoxia, PCr levels decrease 40% and remain at this level during anoxia. A different profile is observed for ATP, with a statistically significant decrease of 23% occurring gradually during 110 min of anoxic perfusion. Intracellular pH decreases significantly with the onset of anoxia, from 7.2 to 6.6 within 50 min. Upon re-oxygenation PCr, ATP and intracellular pH recover to pre-anoxic levels within 60 min. This is the first demonstration of a sustained reversible decrease in ATP levels with anoxia in turtle brain. The observed changes in pH and adenylates, and a probable concomitant increase in adenosine, may represent important metabolic signals during anoxia.

Adenosine Triphosphate↗
PubMed1997

Leptin prevents posthibernation weight gain but does not reduce energy expenditure in arctic ground squirrels.

In mammals, leptin reduces energy intake and may increase energy expenditure as a means to maintain body weight and/or adiposity at an appropriate level. Hibernating mammals seasonally alter body mass, food intake, and body composition and, therefore, represent an attractive model for investigating the physiological regulation of changing body mass and adiposity. Previous experiments in our laboratory demonstrated that administration of mouse recombinant leptin reduces food intake and body weight in arctic ground squirrels during prehibernation fattening. In addition, leptin appeared to reduce metabolic efficiency (weight gain per unit of energy intake). This result suggests that reduced food intake alone may not account for the observed weight loss. Here, we describe the effect of a 3-week constant infusion of leptin given to posthibernation arctic ground squirrels on food consumption and energy expenditure. Mouse recombinant leptin (1 mg/ml) was administered through subcutaneously implanted mini-osmotic pumps (10 microliters/hr flow rate). Resting metabolic rate was monitored before and during the 3-week leptin administration period by indirect calorimetry. Body temperature and locomotory activity were monitored continuously by abdominal radiotransmitters. At the end of the leptin administration period, thermogenic capacity was evaluated by measuring brown fat uncoupling protein-1 mRNA and protein levels. Leptin administration resulted in reduced food intake and prevented posthibernation weight gain, but it did not alter any of the measured parameters of energy expenditure.

Adipose Tissue↗
PubMed1993

The family of genes encoding odorant receptors in the channel catfish.

The anatomical and numerical simplicity of the fish olfactory system has led us to examine the family of olfactory receptors expressed in the catfish. We have identified a family of genes encoding seven transmembrane domain receptors that share considerable homology with the odorant receptors of the rat. The size of the catfish receptor repertoire appears to be far smaller than in mammals. Analysis of the nucleotide sequences suggests that these receptor genes have undergone positive Darwinian selection to generate enhanced diversity within the putative odorant-binding domains. Individual receptor clones anneal with 0.5%-2% of the olfactory neurons, suggesting that a single cell expresses only a small subset of distinct odorant receptors. Each cell, therefore, possesses a unique identity defined by the receptors it expresses. These data suggest that the brain may discriminate among odors by determining which neurons have been activated.

Amino Acid Sequence↗
PubMed1991

A novel multigene family may encode odorant receptors: a molecular basis for odor recognition.

The mammalian olfactory system can recognize and discriminate a large number of different odorant molecules. The detection of chemically distinct odorants presumably results from the association of odorous ligands with specific receptors on olfactory sensory neurons. To address the problem of olfactory perception at a molecular level, we have cloned and characterized 18 different members of an extremely large multigene family that encodes seven transmembrane domain proteins whose expression is restricted to the olfactory epithelium. The members of this novel gene family are likely to encode a diverse family of odorant receptors.

Amino Acid Sequence↗
PubMed1991

R15 alpha 1 and R 15 alpha 2 peptides from Aplysia: comparison of bioactivity, distribution, and function of two peptides generated by alternative splicing.

The mRNA precursor encoded by the R15 gene is alternatively spliced in different neurons to form two related variants, R15-1 and R15-2 mRNA. One of the peptides encoded by the R15-2 mRNA, the R15 alpha 1 peptide, is expressed in the endogenously bursting neuron R15 and mediates some of its central and peripheral synaptic actions. In this study we found that the R15 alpha 2 peptide, which is encoded by the R15-1 mRNA, is synthesized in other neurons in the abdominal ganglion and is also bioactive. The R15 alpha 1 and R15 alpha 2 peptides were found to exert many similar actions on the cardiovascular, digestive, respiratory, and reproductive systems. However, the differences between many of the pharmacological effects of the R15 alpha 1 and R15 alpha 2 peptides indicate that alternative splicing in this system results in two functionally different peptides. Widespread immunoreactivity was found for an antibody directed against the R15 alpha 2 peptide, both in the central nervous system and the periphery. But because of the shared sequence with the R15 alpha 1 peptide, the antibody cross-reacts with the R15 alpha 1 peptide. To distinguish immunocytochemically between the two peptides, we also raised a second antibody that recognizes only the R15 alpha 1 peptide. This antibody labeled the cell body of only one neuron in the central nervous system, R15, although widespread immunoreactivity was found in axons and varicosities in the periphery.

Animals↗
PubMed1991

Interrelations between ego functions and personality traits: their relation to psychotherapy outcome.

Ninety consecutive admissions to a large outpatient clinic of a municipal hospital completed two self-report questionnaires: the Self-Evaluation Questionnaire (SEQ) which consists of four 10-item scales that assessed four areas of ego functioning; and the 89-item Personality Profile Index (PPI) that provided measures of eight dimensions of personality traits and also a measure of conflict. Results indicated that the four measures of ego functioning had good internal consistency, and three of the four ego functions had a highly similar pattern of relations to the personality trait dimensions and to the conflict measure. It thus appears that each set of constructs amplifies and sheds light on the other. Two of the ego function measures were significant predictors of psychotherapy outcome. They correlated highly with one another and also with a third measure of ego functioning. This fact, together with the similarity of their correlations with the personality traits, suggests that these ego functions represent different aspects of an underlying construct that could be called Ego Strength. Therefore, combining the three ego functions into a 30-item Ego Strength measure could provide an even more sensitive predictor of therapy outcome and a useful new instrument for psychotherapy research.

Adult↗
PubMed1989

Purification and sequencing of neuropeptides contained in neuron R15 of Aplysia californica.

R15 is a large identified neuron present in the abdominal ganglion of the mollusc Aplysia. Previous studies have indicated that this neuron may play a role in water balance and possibly renovascular functions. A peptidic factor contained in the neuron R15 has been shown to increase the water content of Aplysia. To determine the structure of the peptides contained in R15, we purified the extracts of 820 R15 cells by means of two steps of reverse-phase HPLC. The purification yielded a number of peptides, only one of which, R15 alpha 1, resulted in water uptake when injected into animals. Determination of the amino acid content and sequence analysis of the R15 alpha 1 peptide demonstrated that this peptide contains 38 residues, including two cysteines. The peptide failed to react with iodoacetate, indicating that the two cysteines are connected by a disulfide bridge. To confirm the assigned structure, the peptide was synthesized with a disulfide bridge. The chromatographic properties and bioactivity of the synthetic material were identical to those of the native peptide. Several other R15 peptides were inactive in the bioassay for water uptake. The sequence of one of these peptides (R15 beta) was determined, and it was established that the peptide contains 28 residues. Amino acid analysis of three other peaks was performed. One of these peaks contained a peptide (R15 beta f) whose amino acid composition suggests that it is a fragment of the R15 beta peptide. The other two peaks contained peptides with identical amino acid compositions, suggesting that they are variants of a single peptide (R15 gamma). The amino acid sequences of all the peptides identified in neuron R15 correspond to stretches of a polyprotein encoded by a recently sequenced R15 cDNA.

Amino Acid Sequence↗
PubMed1989

A comparative study on the effects of brotizolam and flurazepam on sleep and performance in the elderly.

This study was undertaken to compare the effects of 0.25 mg of brotizolam, 15 mg of flurazepam, and placebo on the sleep and performance of elderly subjects with chronic insomnia during a 2-week period of administration. Thirty-six male and female subjects who ranged in age from 60-72 years were divided into three treatment groups. All groups received placebo on the first three study nights, the active drug or placebo on the next 14 nights, and placebo again on the two following withdrawal nights. Sleep was assessed by means of questionnaires, and residual effects during the day were studied by means of the multiple sleep latency test and a variety of memory, performance, and vigilance tests. Sleep improved with all treatments. Rebound insomnia was noted on brotizolam withdrawal; flurazepam withdrawal had a milder impact. At the end of this 19-night study, only the placebo-treated group was sleeping significantly longer than at baseline. Both drug treatments increased daytime sleepiness and impaired performance on the first day after their administration. These effects waned after 2 weeks of treatment with brotizolam, but not flurazepam. The results of this study affirm the increased sensitivity of elderly subjects to benzodiazepine hypnotics and their indication for acute or intermittent insomnia, rather than for the more chronic forms of this disorder.

Aged↗
PubMed1987

Effects of flurazepam and zopiclone on the performance of chronic insomniac patients: a study of ethanol-drug interaction.

Three groups of ten middle-aged insomniac patients were treated with placebo, flurazepam, or zopiclone for 12 consecutive days in a study designed to compare the residual daytime effects of long-acting flurazepam and short-acting zopiclone on a variety of cognitive and motor tasks. These effects were examined independently and in combination with ethanol effects. The effects of the drugs on sleep parameters were also subjectively assessed by means of questionnaires during treatment and withdrawal. The study demonstrated persistent performance effects with flurazepam. Testing at the end of the treatment period showed that movement time was impaired in the flurazepam treated group. Flurazepam also enhanced the increment of movement time produced by ethanol. One subject became severely confused when given ethanol after using flurazepam for 12 days. None of these effects were found with zopiclone. The rapid elimination of zopiclone may account for these findings.

Adult↗
PubMed1986

Driving ability after intravenous fentanyl or diazepam. A controlled double-blind study.

Uncomfortable or moderately painful radiologic diagnostic and therapeutic procedures are being performed increasingly on outpatients. If sedation and analgesia are used, patients cannot drive themselves home or return rapidly to normal activities. This study compares the effect of fentanyl (100 micrograms), diazepam (7.5 mg), and placebo on driving ability of young volunteers as measured by the thacometer. Speed and accuracy were impaired at 30 and 120 minutes by both drugs, and by fentanyl more than diazepam. This study design may be suitable for the assessment of whether patients can drive safely after other analgesic drugs.

Adult↗