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Biomedical subjects

J May

Publications and source records attributed to J May.

At least 37 records · Page 2Linked to original sources
PubMed2003

Noise levels within the ear and post-nasal space in neonates in intensive care.

BACKGROUND: Noise exposure in neonatal units has long been suspected of being a cause of hearing loss associated with such units. The noise intensity to which the neonate is exposed varies with the type of ventilatory support used. Also, the post-nasal space is an enclosed cavity that is close to the inner ear and an area of turbulent and hence potentially noisy airflow. AIM: To determine noise intensities within the ear and post-nasal space in neonates on different modes of ventilatory support using probe microphones, measures previously not undertaken. METHODS: A portable instrument with a probe microphone was used for the measurements. Three groups of infants were included: (a) those receiving no respiratory support (NS); (b) those receiving conventional ventilation (CV); (c) those receiving continuous positive airways pressure (CPAP) support. RESULTS: The mean in-the-ear noise intensities (at 1 kHz) were 41.7 dB SPL (NS), 39.5 dB SPL (CV), and 55.1 dB SPL (CPAP). The noise intensities in the post-nasal space in those receiving CPAP support were higher than in the other groups, reached mean levels of up to 102 dB SPL at some frequencies, and increased with increasing flow rates. CONCLUSIONS: The most important finding is the high noise intensities in the post-nasal space of those receiving CPAP support. Given the proximity of the post-nasal space to the inner ear, enough noise could be transmitted, especially in infants receiving the higher flow rates, to cause cochlear damage and hence hearing loss. It would therefore be wise, wherever possible, to avoid using the higher flow rates.

Cochlea↗
PubMed2003

Endovascular repair of abdominal aortic aneurysm in the multifocal atherosclerotic patient.

One of the major problems of treating aortic aneurysms has been the multifocal nature of atherosclerotic disease. Co-existing cardiovascular disease in the majority of patients together with chronic obstructive airways disease, renal impairment and hostile abdomen in some, has resulted in 1/3 of patients presenting with aortic aneurysms being regarded as high risk and unfit for open repair. Endovascular repair of aortic aneurysm therefore has much to recommend it since it avoids the need for laparatomy, cross clamping of the aorta and the obligatory blood loss associated with opening of the sac. Between May 1992 and March 2003 we have used the endovascular method to repair abdominal aortic aneurysms (AAA) in 583 patients. Successful repair was achieved in 563 patients (96%). The remaining 20 patients required primary conversion to open repair at the original operation. The 30-day perioperative mortality rate was 13 of 583 (2.2%). In this paper we summarise a number of studies that we have undertaken, comparing endovascular with alternative treatment methods and comparing various types of endovascular prostheses. In addition we report the long-term outcome of endovascular AAA repair as it relates to morphological changes in the proximal neck out to 9 years from operation. We conclude that despite the continuing small incidence of device failure, endovascular is the preferred method of AAA repair in the multifocal atherosclerotic patient. This view is based on the low perioperative mortality, superior survival compared with open repair and our experience of long-term stability in the proximal neck in the majority of patients.

Aged↗
PubMed2003

[Influencing factors on the level of the ovulation rate in sheep during the main breeding season--an ultrasonographic study].

The main breeding season for sheep in Germany is from the beginning of September until the end of November. The aim of this study was to determine the factors which influenced the level of the ovulation rate (o. r.) during this period. The examination was conducted over three years and included Booroola. Mutton Merino crosses [heterozygous- (F+) carriers and non-carriers of the Booroola- (FecB) fecundity gene], German Mutton Merino (GMM) and German Blackheaded (GB). In total 1326 examinations were carried out. Between the 8th to 12th day after estrous detection an ovary diagnosis was performed by transrectal scanning with a 7.5 MHz linear probe. The number of the corpora lutea per ewe (o. r.) was documented. The weight and the body condition of the ewes was also determined. During the breeding season the breed of the ewe had the main effect on the level of the o. r. (p < 0.05). This is the reason that the statistical model can only be applied for each breed. The effects of age, year of examination and day of the main breeding season were tested. The age of the ewes and the date of the examination during the breeding season had the main effect on the o. r. In GMM and GB the age influenced the o.r. with an effect of 8.3% and 4.2%. The effect of the season was vice versa (Gmm 3.2%; GB 8.2%). Non-carriers of the Booroola- (FecB) fecundity gene behaved similar like the GMM. However, only the high fecundity carriers of the FecB-gene were strongly influenced by the season. For each breed there exists a typical threshold value for the body weight above which further weight has no effect on the o. r. (GMM 65-70 kg, GB 75-80 kg, non-carriers of the Booroola-FecB gene 55-60 kg and carriers of the FecB-gene 60-65 kg). This value lies at about 80% of the highest measured weight of each breed. The results demonstrated that a balanced age structure in combination with a optimum weight influenced the level of o. r. In addition the date of the season is especially important.

Age Factors↗
PubMed2002

TNFalpha-308A associated with shorter intervals of Plasmodium falciparum reinfections.

A mutation at position -308 of the tumor necrosis factor alpha (TNF-308A) gene promoter has previously been associated with particular manifestations of infectious and non-infectious diseases. In a longitudinal study on malariological parameters in Gabon, TNF promoter variants of 98 children initially presenting with severe Plasmodium falciparum malaria, followed by a total of 504 reinfection events within 52 months, and 100 children initially presenting with mild malaria followed by a total of 342 reinfections were analyzed. Symptomatic P. falciparum reinfections occurred more quickly (median 11 weeks) in carriers of the TNF-308A allele, with severe malaria at enrollment, compared to carriers of other TNF promoter variants (median 16 weeks). The results show that this particular TNF promoter allele increases the risk of reinfection with the malaria parasite P. falciparum.

Animals↗
PubMed2001

Spleen size determined by ultrasound in patients with sickle cell trait, HbAC trait and glucose-6-phosphate-dehydrogenase deficiency in a malaria hyperendemic area (Ashanti Region, Ghana).

The occurrence of enlarged spleens and its age distribution has long been used as a crude measure to estimate malaria endemicity in cross-sectional surveys. Spleen size, however, is influenced by several variables that should be considered if they are observed in a population under study. We hypothesized that spleen indices are dependent on distinct red blood cell polymorphisms. Accordingly, we expected a lower prevalence of splenomegaly among patients with the sickle-cell trait (HbAS), HbAC trait and G6PD deficiency than in patients without red cell disorders, possibly due to the lower incidence of malaria attacks in these individuals. In our survey, however, spleen rates and sizes did not differ significantly between HbAA-, HbAS- and HbAC-positive individuals. Furthermore, enlargement of spleens was found at similar frequencies in persons with and without glucose-6-phosphate-dehydrogenase (G6PD)-deficiency (G6PD-A(-)).

Adolescent↗
PubMed2001

Identification of alkylidene hydrazides as glucagon receptor antagonists.

High throughput screening of our small molecule combinatorial library identified a class of benzoylnaphthalenehydrazones with modest affinity for the human glucagon receptor. Optimization of this initial hit through a series of targeted libraries and traditional medicinal chemistry led to ligands with nanomolar affinities. Pharmacological evaluation demonstrated that these ligands were competitive glucagon receptor antagonists. Intravenous administration of a representative benzoylnaphthalenehydrazone into rats attenuated glucagon-stimulated glucose levels.

Animals↗
PubMed2001

Nitric oxide synthase 2(Lambaréné) (G-954C), increased nitric oxide production, and protection against malaria.

A point mutation in the promoter of the nitric oxide synthase 2 gene (NOS2), termed NOS2(Lambaréné) (NOS2-G954C), protects heterozygous carriers against severe malaria as effectively as the sickle cell trait. In a prospective longitudinal study, 841 individual infections of initially 200 children (151 wild-type vs. 49 NOS2(Lambaréné) carriers) were monitored for 4 years, to assess the rates of malarial attacks in the 2 groups; carriers of the NOS2(Lambaréné) polymorphism were significantly less likely to experience malarial attacks than were others (P=.002). The distribution of the NOS2(Lambaréné) polymorphism was investigated in malaria-endemic areas. It was found to be present with the highest frequency in Africa and at a lower frequency in Asia. Ex vivo studies showed that cells isolated from people with this polymorphism have a 7-fold higher baseline NOS activity, compared with the levels detected in cells from subjects with the wild-type gene (P=.003).

Case-Control Studies↗
PubMed2001

Endoluminal repair of abdominal aortic aneurysms - state of the art.

This paper considers the historical aspects of endovascular aneursym repair; the major findings of our Departments experience over an 812-year period and reviews recent developments in endovascular prostheses. Analysis of 400 patients undergoing primary repair of abdominal aortic aneurysm between 1992 and 2000 revealed a perioperative mortality rate of 2.7% and primary conversion rate of 5%. With sequential studies it was shown that the outcome was better with bifurcated/aorto uni iliac grafts than tube grafts; better with second generation prostheses than first generation protheses and that survival in consecutive patients treated concurrently by open repair and endoluminal repair was superior in the endoluminal group. Endoluminal AAA repair is at a critical point of its development. It is unquestioned that it can dramatically reduce the need for intensive care and length of hospital stay and more recently it has been reported that survival is improved compared with open repair. The need for lifetime surveillance, the probability of graft failure and need for re-intervention, however, negate some of the advantages. The small incidence of unpredictable rupture following endoluminal AAA repair is a timely reminder of the need for continued careful follow-up.

Aortic Aneurysm, Abdominal↗
PubMed2001

Latency associated promoter transgene expression in the central nervous system after stereotaxic delivery of replication-defective HSV-1-based vectors.

The herpes simplex virus type 1 (HSV-1) latency associated promoter (LAP) has been shown to sustain long-term reporter gene expression within sensory neurones. Its activity within the CNS is, however, less well understood. In this study we characterise the activity of the LAP after stereotaxic delivery of recombinant HSV-1-based vectors to the brain. Two classes of vectors were utilised in these studies: (1) a replication-defective vector lacking the glycoprotein H and thymidine kinase genes, designated CS1, and (2) a virus mutant severely impaired for immediate-early (IE) gene expression which lacks functional VP16, ICP4 and ICP0 genes, designated in1388. Both vectors contain the LacZ gene under the control of the LAP. Following delivery of either vector to the striatum, beta-gal expression was detected within anatomically related CNS regions distal to the site of injection. At these sites the number of beta-gal-positive cells increased with time and remained stable up to 4 weeks p.i. beta-Gal expression could not be detected at the site of injection after delivery of CS1 but beta-gal expression within neurones located at this site was observed after delivery of in1388, indicating reduced toxicity of this severely disabled virus. Transgene expression decreased dramatically with both vectors at later time-points (>4 weeks after delivery), but PCR analysis demonstrated that viral genomes were stably maintained for up to 180 days following delivery, indicating that the loss of beta-gal-positive neurones was not likely to be due to a loss of vector-transduced cells. Moreover, after delivery of an equivalent virus to the rat striatum in situ hybridisation analysis showed a similar decrease in the number of neurones expressing the endogenous LATs with time. These data indicate that although the HSV-1 LAP can drive the expression of foreign genes in a variety of CNS neurones, in these cells there is a slow down-regulation of the viral promoter which eventually results in the loss of detectable transgene expression.

Animals↗
PubMed2001

Gatekeeping and legitimization: how informal carers' relationship with health care workers is revealed in their everyday interactions.

AIM(S) OF THE STUDY: This study explores the relationship between informal carers of older people, and health care workers within the context of a hospital ward. Through an analysis of their language-based encounters the purpose of the study was to identify the discursive processes involved in face-to-face informal carer-health care worker interactions, during the course of carers' visits to one elderly care rehabilitation hospital ward. DESIGN: An ethnomethodological research design, which encompassed the concerns of conversation analysis and the study of institutional interaction, was used. The study involved videotape recording informal carers naturally occurring spontaneous interactions with a range of health care workers on the ward. Data collection was carried out for between 1 and 3 hours, two to three times a week over a period of 3 months. The data comprised: 30 dyadic and group interactions involving 19 different carers and 25 different health care workers, including nurses (qualified and unqualified), physiotherapists, occupational therapists, dieticians, ambulance personnel, housekeepers and nursing auxiliaries. Detailed transcriptions of the data were produced and analysis was undertaken using a modified conversation analysis approach. FINDINGS: Analysis revealed that a central aspect of the way the relationship between informal carers and health care workers is framed is by the way information and access to information is obtained. This paper examines some of the aspects of informal carer-health care worker discourse, which denote both parties as gatekeepers. In doing so it considers the roles that legitimatization of competence and knowledgeability have in facilitating informal carers interactions with health care workers. CONCLUSIONS: We conclude that the accomplishment of legitimacy is largely a collaborative undertaking on behalf of health care workers and informal carers. The implications of these findings for carers, health care workers, policy and future research are discussed.

Adult↗
PubMed2001

Evidence for a reduced effect of chloroquine against Plasmodium falciparum in alpha-thalassaemic children.

Alpha-thalassaemia is common in malaria-endemic regions and is considered to confer protection from clinical disease due to infection with Plasmodium falciparum. In vitro, sensitivity to chloroquine (CQ) of P. falciparum infecting alpha-thalassaemic erythrocytes is reduced. We examined, in a cross-sectional study of 405 Nigerian children, associations between alpha-globin genotypes, blood concentrations of CQ, and P. falciparum parasitaemia. Of the children, 44% were alpha+-thalassaemic (36.8% heterozygous, 7.6% homozygous). CQ in blood and P. falciparum-infection were observed in 52 and 80%, respectively. CQ was more frequently found in homozygous alpha+-thalassaemic (71%) than in non-thalassaemic children (50%; odds ratio, 2.42; 95% confidence interval, 1.01-5.8). Among children with CQ in blood and despite similar drug concentrations, alpha+-thalassaemic individuals had fewer infections below the threshold of microscopy which were detectable by PCR only, and they had a higher prevalence of elevated parasitaemia than non-thalassaemic children. No such differences were discernible among drug-free children. CQ displays a lowered efficacy in the suppression of P. falciparum parasitaemia in alpha+-thalassaemic children; hence protection against malaria due to alpha+-thalassaemia may be obscured in areas of intense CQ usage. Moreover, alpha+-thalassaemia may contribute to the expansion of CQ resistance.

Animals↗
PubMed2001

Improved survival after endoluminal repair with second-generation prostheses compared with open repair in the treatment of abdominal aortic aneurysms: a 5-year concurrent comparison using life table method.

PURPOSE: The aim of this study was to compare the outcome of consecutive patients with abdominal aortic aneurysm (AAA) treated concurrently by means of open repair (OR) and endoluminal repair (ER) with second-generation prostheses by the same surgeons during a defined interval. METHODS: Between May 1995 and December 1998 second-generation (low profile, fully supported, modular) endoprostheses were implanted in 148 patients. These patients, together with 135 patients treated concurrently with OR during the same period, comprised the study group of 283 patients. Patient selection was based on aneurysm morphology. Those patients who were anatomically suitable for ER were treated with this method. The ER and OR groups were similar with regard to age, sex, and size of AAA. The ER group contained high-risk patients considered unfit for OR (n = 46), and the OR group contained high-risk patients who were anatomically unsuitable for ER (n = 19). Outcome criteria in both groups were survival and successful aneurysm repair. Success in the ER group was defined as exclusion of the aneurysm sac and stability or reduction in AAA maximum transverse diameter. Persistent endoleaks were classified as failures, regardless of whether they were subsequently corrected with secondary endovascular intervention. Data were analyzed with the life table method. The minimum period of follow-up for all patients was 18 months. RESULTS: The perioperative mortality rate was 5.9% in the OR group and 2.7% in the ER group (not significant). There was a statistically significant difference between the survival curves of the two groups in favor of the ER group when analyzed with the log-rank test (P =.004). The Kaplan-Meier curve for graft failure for the ER group revealed a 3-year graft success probability of 82%. Survival probability with successful repair in the OR group at 3 years was 85%. CONCLUSIONS: A concurrent comparison of ER with second-generation prostheses versus OR demonstrated a significant difference in survival in favor of the ER group. The probability of survival with successful repair at 3 years was similar in both groups.

Aged↗
PubMed2001

Specifying executive representations and processes in number generation tasks.

The Interacting Cognitive Subsystems framework, ICS (Barnard, 1985) proposes that central executive phenomena can be accounted for by two autonomous subsystems, which process different forms of meaning: propositional and schematic (implicational) meanings. The apparent supervisory role of the executive arises from limitations on the exchange of information between these and other cognitive subsystems. This general proposal is elaborated in four experiments in which a total of 1,293 participants are asked to spontaneously generate a large verbal number to varying task constraints, with the intention of specifying the representations of number and task that underlie responses. Responses change systematically according to participants' use of explicit propositional information provided by the instructions, and inferred implicational information about what the experimenter is requesting. There was a high error rate (between 6% and 24%), participants producing responses that did not fall within the large range indicated by the instructions. The studies support the distinction between propositional and implicational processing in executive function, and provide a framework for understanding normal executive representations and processes.

Cognition↗
PubMed2001

Antigenic variation within the CD4 binding site of human immunodeficiency virus type 1 gp120: effects on chemokine receptor utilization.

To assess the antigenicity of envelope glycoproteins derived from primary human immunodeficiency virus type 1 populations, their interactions with the receptor CD4, and their coreceptor usage, we have cloned and expressed multiple gp120 proteins from a number of primary virus isolates. Characterization of these proteins showed a high degree of antigenic polymorphism both within the CD4 binding site and in defined neutralization epitopes, which may partially account for the general resistance of primary isolates to neutralizing agents. Furthermore, chimeric viruses expressing gp120 proteins with reduced CD4 binding abilities are viable, suggesting that primary viruses may require a less avid interaction with the receptor CD4 to initiate infection than do their laboratory-adapted counterparts. The coreceptor usage of chimeric viruses was related to the ability of the virus to bind CD4, with reduced CD4 binding correlating with preferential usage of CXCR4. Changes in coreceptor usage mapped to sequence changes in the C2 and V4 regions, with no changes seen in the V3 region.

Amino Acid Sequence↗
PubMed2001

Effects of visuospatial tasks on desensitization to emotive memories.

OBJECTIVES: Intrusive memories of extreme trauma can disrupt a stepwise approach to imaginal exposure. Concurrent tasks that load the visuospatial sketchpad (VSSP) of working memory reduce the vividness of recalled images. This study tested whether relief of distress from competing VSSP tasks during imaginal exposure is at the cost of impaired desensitization. DESIGN: This study examined repeated exposure to emotive memories using 18 unselected undergraduates and a within-subjects design with three exposure conditions (Eye Movement, Visual Noise, Exposure Alone) in random, counter-balanced order. METHOD: At baseline, participants recalled positive and negative experiences, and rated the vividness and emotiveness of each image. A different positive and negative recollection was then used for each condition. Vividness and emotiveness were rated after each of eight exposure trials. At a post-exposure session 1 week later, participants rated each image without any concurrent task. RESULTS: Consistent with previous research, vividness and distress during imaging were lower during Eye Movements than in Exposure Alone, with passive visual interference giving intermediate results. A reduction in emotional responses from Baseline to Post was of similar size for the three conditions. CONCLUSION: Visuospatial tasks may offer a temporary response aid for imaginal exposure without affecting desensitization.

Adolescent↗
PubMed2001

The effects of age and sex on susceptibility to motion sickness.

BACKGROUND: The present investigation is concerned with the role of sex, age and experience in determining motion sickness susceptibility. HYPOTHESIS: Motion sickness susceptibility varies with sex and age, and may be related to the level of physical activity sustained by the individual. METHODS: Three surveys were conducted. The first included school age children (9-18 yr) and addressed motion experience and motion sickness on 13 forms of transport. The second questionnaire sought to determine whether these sex differences could be understood in terms of differential involvement in various forms of physical activity. The third survey addressed the role of age and sex effects in a college age population. RESULTS: The first study revealed significantly greater motion sickness for female as compared with male subjects on devices with which both groups were equivalent in terms of exposure history. The second study showed little relation between an individual's level of physical activity and susceptibility to motion sickness. The results of the third study were in essential agreement with the first survey and revealed no significant interactions between age and sex, suggesting that sex differences remain stable across this age range. CONCLUSION: Our conclusions regarding these surveys are that sex differences in motion sickness do not vary significantly with age and cannot be accounted for by differences in exposure to motion or physical activity. There was also little evidence for the notion that men are more reticent to report motion sickness.

Adolescent↗