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Biomedical subjects

B Young

Publications and source records attributed to B Young.

At least 37 records · Page 2Linked to original sources
PubMed2001

Hepatitis B surface antigen variants in vaccinees, blood donors and an interferon-treated patient.

Variants of hepatitis B virus (HBV), with amino acid substitutions in the major antigenic "a" determinant of hepatitis B surface antigen (HBsAg), have been described mainly in vaccinated children. In the present study in addition to vaccinated children, we have investigated Chinese blood donors positive for anti-HBc alone, and a patient with continuing liver disease after interferon-induced seroconversion to anti-HBs. Variants were detected in two of four children with break-through infections. One child had a double mutation (P142S and G145R) and the other a G145A substitution. Three of seven anti-HBc positive Chinese blood donors had a T131I substitution, whilst the interferon-treated patient had a treble amino acid substitution (P142S, G145R and N146D). The present results indicate that HBsAg variants may exist in individuals other than vaccinated children.

Amino Acid Sequence↗
PubMed2001

Inflammation and dietary protein intake exert competing effects on serum albumin and creatinine in hemodialysis patients.

BACKGROUND: Cross-sectional studies have shown an inverse correlation between serum C-reactive protein (CRP) and serum albumin concentration in hemodialysis patients. The net effects of inflammation and dietary protein intake on nutritional markers over time are unknown. METHODS: To explore the effects of CRP and normalized protein catabolic rate (nPCR) on serum albumin and creatinine, we analyzed six consecutive months of laboratory data from 364 hemodialysis patients, using a multivariable Mixed model with conservative biases. RESULTS: The overall trend over time in serum albumin was slightly positive (0.039 g/dL/month) and in serum creatinine slightly negative (-0.052 mg/dL/month). With increasing CRP, serum albumin declined significantly (-0.124 g/dL/month per unit increase in log CRP, adjusted for age, gender, race, diabetes, and nPCR, P < 0.0001). Serum albumin increased with increasing nPCR (0.021 g/dL/month per 0.1 g/kg/day, P < 0.0001). The effect of CRP on albumin was attenuated in African Americans and at a higher nPCR. Corresponding values for creatinine mirrored those for albumin. With increasing CRP, creatinine declined significantly [-0.142 mg/dL/month per unit increase in log CRP, adjusted for age, gender, race, diabetes (time since initiation of dialysis; vintage), Kt/V, and nPCR, P = 0.002]. Serum creatinine increased with increasing nPCR (0.183 mg/dL/month per g/kg/day, P < 0.0001). CONCLUSIONS: Proxies of inflammation and dietary protein intake exert competing effects on serum albumin and creatinine in hemodialysis patients. These data provide a rationale for prospective testing of dietary protein supplementation in hemodialysis patients with biochemical evidence of ongoing inflammation and "malnutrition."

Adult↗
PubMed2001

Close relationships between Asian American and European American college students.

The authors examined attitudes and behaviors regarding close relationships between European and Asian Americans, with a particular emphasis on 5 major subgroups of Asian Americans (Chinese, Japanese, Korean, Vietnamese, and Filipino Americans). Participants were 218 Asian American college students and 171 European American college students attending a culturally diverse university. The European Americans did not differentiate among the various subgroups of Asian Americans. Their attitudes regarding close relationships were less positive toward Asian Americans than toward Mexican and African Americans, a finding contrary to the prediction of social exchange theory (H. Tajfel, 1975). In contrast to the European Americans' view of homogeneity among Asian Americans, the 5 major subgroups of Asian Americans expressed a distinctive hierarchy of social preference among themselves. Results are discussed in terms of their implications for future research on interethnic relations involving Asian Americans.

Adolescent↗
PubMed2001

Identification of Dekkera bruxellensis (Brettanomyces) from wine by fluorescence in situ hybridization using peptide nucleic acid probes.

A new fluorescence in situ hybridization method using peptide nucleic acid (PNA) probes for identification of Brettanomyces is described. The test is based on fluorescein-labeled PNA probes targeting a species-specific sequence of the rRNA of Dekkera bruxellensis. The PNA probes were applied to smears of colonies, and results were interpreted by fluorescence microscopy. The results obtained from testing 127 different yeast strains, including 78 Brettanomyces isolates from wine, show that the spoilage organism Brettanomyces belongs to the species D. bruxellensis and that the new method is able to identify Brettanomyces (D. bruxellensis) with 100% sensitivity and 100% specificity.

Base Sequence↗
PubMed2001

Choosing and using services for sexual health: a qualitative study of women's views.

OBJECTIVE: To explore women's accounts of choosing and using specialist services for sexual health. METHODS: A qualitative study involving semistructured interviews with 37 women screened for Chlamydia trachomatis attending genitourinary medicine and family planning clinics in an East Midlands health authority. RESULTS: In making the decision to seek help, women act on a range of specific prompts, including lay ideas about the significance of symptoms; their own behaviour; their partner's symptoms or behaviour; contact tracing; and health promotion. Some women do not seek help specifically in relation to sexual health but are identified as being at risk of sexually transmitted infections (STIs) during routine consultations. Important influences on women's choice of services include the lay referral system, "insider" knowledge of health services, referral by health professionals, and need to have alternatives to general practice care. Women's willingness to access services is mediated by psychosocial factors such as embarrassment. They may use smear tests as a legitimate opportunity to raise questions about sexual health. Women's priorities for services are that their feelings of stigma and embarrassment are managed appropriately; that staff communicate well and are sensitive to their emotions and comfort during tests and procedures; that they are "in control" when obtaining test results; and that confidentiality is preserved. CONCLUSIONS: A detailed understanding of both lay people's response to symptoms or behaviour that indicates risk of an STI and their needs when using services should inform interventions aimed at encouraging secondary prevention of STIs.

Adolescent↗
PubMed2000

Common firing patterns of hippocampal cells in a differential reinforcement of low rates of response schedule.

Lesion studies show that the hippocampus is critically involved in timing behavior, but so far there has been little analysis of how it might encode time. We recorded the activity of 266 CA1 neurons, 51 CA3 neurons, and 219 entorhinal neurons from rats performing on a differential reinforcement of low rates (DRL) 15 sec schedule in which reinforcement was contingent on responses that occurred at least 15 sec after the preceding response. The unit data were analyzed using two different methods. First, each unit was subjected to an ANOVA that examined the effects of the following: (1) the outcome of the previous response (reward or nonreward); (2) the outcome of the response on which the firing of the cell was synchronized; and (3) time. This showed that, for CA1, CA3, and entorhinal cortex, changes in unit activity were related to all aspects of the task, with the firing of >90% of units recorded in each region being related to at least one of the three factors. Second, intercorrelations between the firing profiles of individual units revealed several functional categories of hippocampal neurons but no clear categories of entorhinal neurons. Of the hippocampal categories, the most common profile was an initial increase in unit activity at the beginning of the DRL interval, followed by a gradual decrease throughout the interval. We suggest that this profile reflects temporal decay in circuits that may code details of the previous trial and that could be used to "time" the DRL interval.

Analysis of Variance↗
PubMed2000

Eating behaviour and its variability in 1-year-old children.

As part of a longitudinal study of the development of eating behaviour, the naturally occurring meals of 30 12 month old children were videotaped on four occasions, all in their own homes. Their mealtime behaviour was coded using a scheme developed for the analysis of feeding behaviour over the weaning period, and summarised as counts of coded actions. Thirty of these meals were coded independently by a second observer. With one exception, the reliability of the counts was high (r> 0.9). The median duration of the meals was 17 min (range 1-50) and the median number of times the mother directly gave the child food was 42 (0-172). The median number of food refusals by the child was 11 (0-89), and self feeding actions, 12 (0-101). Counts of eating behaviour for the main and sweet courses during the same meal were only modestly correlated. Between subject variance for different behaviour counts comprised 41% to 54% of the total variance. These results show that 1 year old children are relatively variable in their eating behaviour from meal to meal, so measures taken from a single meal will not reliably summarise children's feeding characteristics. Food refusal is a common feature of eating behaviour in normal children at this age.

Feeding Behavior↗
PubMed2000

Nicotine attenuates arachidonic acid-induced overexpression of nitric oxide synthase in cultured spinal cord neurons.

Primary spinal cord trauma can initiate a cascade of pathophysiologic events which markedly contribute to the expansion and amplification of the primary insult. The detailed mechanisms of these secondary neurochemical reactions are largely unknown; however, they involve membrane lipid derangements with the release of free fatty acids, in particular, arachidonic acid (AA). AA can induce several injury effects on spinal cord neurons. We hypothesize that upregulation of nitric oxide synthase (NOS) is among the most important mechanisms of arachidonic-acid-induced neuronal dysfunction and that nicotine can attenuate this effect. To study these hypotheses, spinal cord neurons were exposed to AA and/or nicotine, and several markers of neuronal nitric oxide synthase (nNOS) metabolism were measured. In addition, cotreatments with either inhibitors of nicotinic receptors or inhibitors of specific NOS isoforms were employed. Treatment with AA markedly increased activity of nNOS, as well as mRNA and protein levels of this enzyme. Changes in nNOS expression were accompanied by an increase in cellular cGMP and medium nitrite levels. Pretreatment with nicotine decreased AA-induced overexpression of nNOS and elevation of nitrite levels. In addition, it appeared that these nicotine effects could be partially modulated both by the alpha7 nicotinic receptors or by nonreceptor mechanisms. Alternatively, the observed changes could also be mediated by an alternate nicotinic receptor mechanism which is not blocked by alpha-bungarotoxin or mecamylamine. Results of the present study indicate that exposure to AA can lead to induction of nNOS in cultured spinal cord neurons. In addition, nicotine can exert a neuroprotective effect by attenuation of AA-induced upregulation of nNOS metabolism. These data may have therapeutic implications for the treatment of acute spinal cord trauma.

Animals↗
PubMed2000

Coma mimicking brain death following baclofen overdose.

Baclofen toxicity can be a cause of profound coma with brainstem dysfunction mimicking brain death, and is mainly a clinical diagnosis. Measuring plasma levels is not always possible and may be misleading. Imaging results are usually normal. Electroencephalography may show a pattern of burst suppression. At present no effective specific therapy is available. However, as demonstrated in our case, the prognosis can be good even in severe cases, provided it is recognized early enough, and appropriate supportive measures are instituted.

Baclofen↗
PubMed2000

Neuroplasticity in specific limbic system circuits may mediate specific kindling induced changes in animal affect-implications for understanding anxiety associated with epilepsy.

In two complementary experiments, we studied the effects of low frequency stimulation (LFS) of the amygdala on behavioral effects of kindling in rats and cats. These studies tested the hypothesis that kindling induced long term potentiation (KLTP) in amygdala circuits underlies interictal behavioral change. Since LFS can depotentiate LTP, it was predicted that LFS should both depotentiate KLTP and reverse behavioral effects of kindling. In cats, the effects of LFS on KLTP of amygdala efferents was studied, and related to behavioral effects. Partial ventral hippocampal kindling in cats and right amygdala kindling in rodents lastingly increased defensive response to rats in cats, and anxiety-like behavior (ALB) in the elevated plus-maze in rats. In addition, partial kindling reduced predatory attack behavior in cats independent of its effects on defensive response. Partial kindling also induced KLTP of amygdala efferent transmission to ventromedial hypothalamus (VMH) and periaqueductal gray (PAG) in left and right hemispheres. Depotentiation of amygdala efferent KLTP by bilateral amygdala LFS selectively reduced KLTP in right amygdala efferents. At the same time, defensive behavior, but not attack behavior, was returned to levels seen prior to partial kindling. Defensiveness returned to post kindling levels between 44 and 76days after LFS. At the same time, LTP was restored in the right Amygdalo-PAG pathway only. These findings suggest that lasting change in affect produced by kindling depends on LTP of right amygdala efferent transmission to PAG, replicating studies of the effects of FG-7142 on brain and behavior in the cat. The findings suggest further that the spectrum of behavioral changes produced by partial kindling are dependent on changes in a variety of neural circuits, and that amygdala efferent transmission changes are responsible for changes in defensive behavior, but not attack behavior. Effects of LFS were not due to damage, as thresholds to evoke amygdala efferent response were unchanged. Other data suggest KLTP and depotentiation in right Amygdalo-PAG may reflect changes in glutamate receptor density/synapse number. Kindling effects on rat ALB persisted for at least 1month. Bilateral but not unilateral amygdala LFS reversed the effects of kindling on risk assessment in the plus maze for at least 3weeks. Bilateral LFS also reversed the effects of kindling on open arm exploration, but effects were shorter lived, appearing at 1day but not 3weeks after kindling and LFS. These findings are consistent with other studies which suggest that amygdala neuroplasticity in separable amygdala circuits mediates lasting changes in open arm avoidance and risk assessment. Taken together, the findings of both studies support the hypothesis that a form of LTP of specific amygdala circuits underlies lasting changes in affect produced by limbic kindling. Clinical implications of these findings are discussed.

Aggression↗
PubMed2000

Rapid detection, identification, and enumeration of Pseudomonas aeruginosa in bottled water using peptide nucleic acid probes.

A new chemiluminescent in situ hybridization (CISH) method that provides simultaneous detection, identification, and enumeration of Pseudomonas aeruginosa in bottled water within 1 working day has been developed. Individual micro-colonies of P. aeruginosa were detected directly on membrane filters following 5 h of growth by use of soybean peroxidase-labeled peptide nucleic acid (PNA) probes targeted to a species-specific sequence in P. aeruginosa rRNA. Within each micro-colony, reaction of the peroxidase with a chemiluminescent substrate generated light that was subsequently captured by film or with a digital camera system. Each spot of light represented one micro-colony of P. aeruginosa. Sensitivity and specificity for the identification of P. aeruginosa were 100% as determined by testing 28 P. aeruginosa strains and 17 other bacterial species that included closely related Pseudomonas species. Furthermore, the number of micro-colonies of P. aeruginosa represented by light spots correlated with counts of visible colonies following sustained growth. We conclude that PNA CISH speeds up traditional membrane filtration techniques and adds the specificity of PNA probe technology to generate fast and definitive results.

Bacteriological Techniques↗
PubMed2000

Monitoring phase-specific gene expression in Histoplasma capsulatum with telomeric GFP fusion plasmids.

Dimorphism is an essential feature of Histoplasma capsulatum pathogenesis, and much attention has been focused on characteristics that are unique to the saprophytic mycelial phase or the parasitic yeast phase. Recently, we identified a secreted calcium-binding protein, CBP, that is produced in large amounts by yeast cells but is undetectable in mycelial cultures. In this study, the green fluorescent protein (GFP) was established as a reporter in H. capsulatum to study regulation of CBP1 expression in cultures and in single cells grown under different conditions and inside macrophages. One GFP version that was optimized for human codon usage yielded highly fluorescent Histoplasma yeast cells. By monitoring GFP fluorescence during the transition from mycelia to yeast, we demonstrated that the CBP1 promoter is only fully active after complete morphological conversion to the yeast form, indicating for the first time that CBP1 is developmentally regulated rather than simply temperature regulated. Continuous activity of the CBP1 promoter during infection of macrophages supports the hypothesis that CBP secretion plays an important role for Histoplasma survival within the phagolysosome. Broth cultures of Histoplasma yeasts carrying a CBP-GFP protein fusion construct were able to secrete a full-length fluorescent fusion protein that remained localized within the phagolysosomes of infected macrophages. Additionally, a comparison of two Histoplasma strains carrying the CBP1 promoter fusion construct either epichromosomally or integrated into the chromosome revealed cell-to-cell variation in plasmid copy number due to uneven plasmid partitioning into daughter cells.

Animals↗
PubMed2000

Effect of zidovudine resistance mutations on virologic response to treatment with zidovudine-lamivudine-ritonavir: genotypic analysis of human immunodeficiency virus type 1 isolates from AIDS clinical trials group protocol 315.ACTG Protocol 315 Team.

The effect of baseline drug resistance mutations on response to zidovudine, lamivudine, and ritonavir was evaluated in zidovudine-experienced persons infected with human immunodeficiency virus type 1 (HIV-1). Presence of the K70R mutation was associated with significantly higher plasma HIV-1 RNA levels at baseline. However, presence of resistance mutations did not affect the increase in plasma HIV-1 RNA during a 5-week drug washout, nor was there any effect on first-phase virus decay rates after initiation of therapy or on the probability of having plasma HIV-1 RNA levels <100 copies/mL at week 48. Polymorphisms at protease codons 10, 36, and 71 were associated with significantly faster second-phase decay rates. Suppression of plasma HIV-1 RNA despite presence of zidovudine resistance mutations implies that the presence of these mutations does not preclude a durable response to treatment with a potent 3-drug regimen.

Adult↗
PubMed2000

Prospective comparison of the effect of direct current electrical stimulation and pulsed electromagnetic fields on instrumented posterolateral lumbar arthrodesis.

The purpose of this prospective study was to compare the effect of adjunctive direct current (DC) electrical stimulation and pulsed electromagnetic field therapy (PEMF) on augmentation of instrumented lumbar fusion. Sixty-one patients undergoing lumbar spine fusion were enrolled in the study and randomized to one of three treatment protocols: 1) adjunctive PEMF group (n = 22) fitted with Spinal-Stim model 8212(AME) within 30 days of surgery; 2) DC group (n = 17) had a SpF-2T stimulator(EBI) implanted at the time of surgery; or 3) control group (n = 22). The fusion mass bone mineral density (BMD) assessment was performed on 3-month and 1-year radiographs for each patient. Lateral flexion-extension and anteroposterior radiographs were evaluated at 1 year to determine the presence of fusion. Clinical outcome patient analyses were performed at 1 year. At 1-year follow-up, radiographic fusion and fusion mass bone density were not significantly different among the groups. In the nonstimulated group, there were 43% excellent, 43% good, and 14% fair results. In the PEMF group, there were 35% excellent, 50% good, 10% fair, and 5% poor results. In the DC group, there were 32% excellent, 37% good, and 31% fair results. The results of the current study suggest that electrical stimulation does not significantly enhance fusion rate in instrumented lumbar arthrodesis, although we observed a statistically insignificant trend toward increased fusion mass BMD in the electrically stimulated groups. The significance of increased BMD remains unknown.

Adult↗