Biomedical subjects

D Jackson

Publications and source records attributed to D Jackson.

At least 55 records · Page 3Linked to original sources

PubMed1999

Guidelines for low back pain: changes in GP management.

BACKGROUND: Management guidelines are aimed at reducing inappropriate practice and improving efficiency; however, the effectiveness of many guidelines has yet to be confirmed. This study targets GPs' management of back pain and its relationship with the recent management guidelines. OBJECTIVES: We aimed to investigate changes in GP management of low back pain, low back pain episode duration and time before consultation, over a 5-year period. METHOD: A case series report of 574 patient notes was collected from a large practice in North Yorkshire (January 1992-March 1997). In addition, 713 referral notes from 26 practices across North Yorkshire were collected. The patients were potential subjects for a larger randomized controlled trial evaluating the effectiveness of an exercise programme. Both groups of data were analysed by identifying trends over time and using log linear regression. RESULTS: Recommendation of activity or exercise was found to be a trend increasing over time. In contrast, recommendation to rest was found to be a trend decreasing over time. Activity or exercise was more frequently recommended to younger patients. There was evidence that individuals are seeking a GP consultation more quickly. CONCLUSIONS: The gap between GP practice and the recent guidelines appears to be reducing. However, many variations in practice still exist. Evidence of decreasing time before consultations may indicate that the level of self-care by low back pain patients is decreasing. Although management guidelines may have some effect, there is some way to go before back pain management is optimized.

Adolescent↗

PubMed1999

Control of phyllotaxy in maize by the abphyl1 gene.

Organogenesis in plants occurs at the shoot apical meristem, a group of indeterminate stem cells that are organized during embryogenesis. Regulated initiation of leaves or flowers from the shoot meristem gives rise to the familiar geometric patterns observed throughout the plant kingdom. The mechanism by which these patterns, termed phyllotaxies, are generated, remains unclear. Maize plants initiate leaves singly, alternating from one side to the other in a regular pattern. Here we describe a recessive maize mutant, abphyl1, that initiates leaves in opposite pairs, in a pattern termed decussate phyllotaxy. The decussate shoot meristems are larger than normal throughout development, though the general structure and organization of the meristem is not altered. abph1 mutants are first distinguished during embryogenesis, prior to true leaf initiation, by a larger shoot meristem and coincident larger expression domain of the homeobox gene knotted1. Therefore, the abph1 gene regulates morphogenesis in the embryo, and plays a role in determining the phyllotaxy of the shoot.

Gene Expression Regulation, Developmental↗

PubMed1999

Leaf senescence is delayed in tobacco plants expressing the maize homeobox gene knotted1 under the control of a senescence-activated promoter.

Leaf senescence is an active process involving remobilization of nutrients from senescing leaves to other parts of the plant. Whereas senescence is accompanied by a decline in leaf cytokinin content, supplemental cytokinin delays senescence. Plants that overexpress isopentenyl transferase (ipt), a cytokinin-producing gene, or knotted1 (kn1), a homeobox gene, have many phenotypes in common. Many of these phenotypes are characteristic of altered cytokinin physiology. The effect of kn1 on leaf senescence was tested by driving its expression using the promoter of the senescence-associated gene SAG12. SAG:kn1 tobacco plants showed a marked delay in leaf senescence but otherwise developed normally. The delay in senescence was revealed by an increase in chlorophyll content in SAG:kn1 leaves relative to leaves of the control plants and by a decrease in the number of dead leaves. Senescence was also delayed in detached leaves of SAG:kn1 plants. Delayed senescence was accompanied by increased leaf cytokinin content in older leaves expressing kn1. These experiments extend the current understanding of kn1 function and suggest that in addition to mediating meristem maintenance, kn1 is capable of regulating the onset of senescence in leaves.

Aging↗

PubMed1998

Subsensitivity to dopaminergic drugs in periadolescent rats: a behavioral and neurochemical analysis.

It has been reported that post-natal day (PD) 30-40 rats respond differently to the behavioral effects of dopaminergic drugs when compared to younger or older rats. In this study, the behavioral effects of amphetamine (AMPH) on motor behavior and the effects of dopaminergic drugs on striatal acetylcholine (ACh) release were evaluated in periadolescent (PD35) and adult rats. AMPH increased dopamine (DA)-mediated motor behaviors (locomotor activity and stereotypy) in periadolescent and adult rats; however, these responses were of a lesser magnitude in periadolescent rats. In adult rats, cocaine and nomifensine inhibited ACh overflow in a dose-dependent manner. In periadolescent rats, ACh overflow was maximally inhibited at a lower drug concentration (5 microM) than in adult rats (10 microM) signifying increased sensitivity in these rats. Apomorphine inhibited ACh overflow in a dose-dependent fashion in slices from adult rats. In contrast, apomorphine did not consistently inhibit ACh overflow in striatal slices prepared from periadolescent rats. Collectively, the results of this study demonstrate behavioral subsensitivity to AMPH in periadolescent rats. Examination of the effects of DA reuptake blockers on DA modulation of striatal cholinergic neurons failed to reveal a corresponding subsensitivity. In fact, ACh release was more sensitive to DA reuptake blockers in periadolescent rats. This latter finding suggests that undisclosed factors override dopaminergic modulation of striatal neurons in the mediation of behavior in periadolescent rats. We propose that during periadolescence, DA transmission is transiently elevated. This results in post-synaptic supersensitivity of cholinergic receptors and consequently induces behavioral subsensitivity when challenged with dopaminergic drugs. Increased cholinergic tone may mediate behavioral subsensitivity despite drug-induced elevations in DA.

Acetylcholine↗

PubMed1998

The BirthPlace collaborative practice model: results from the San Diego Birth Center Study.

Objective: The search for quality, cost-effective health care programs in the United States is now a major focus in the era of health care reform. New programs need to be evaluated as alternatives are developed in the health care system. The BirthPlace program provides comprehensive perinatal services with certified nurse-midwives and obstetricians working together in an integrated collaborative practice serving a primarily low-income population. Low-risk women are delivered by nurse-midwives in a freestanding birth center (The BirthPlace), which is one component of a larger integrated health network. All others are delivered by team obstetricians at the affiliated tertiary hospital. Wellness, preventive measures, early intervention, and family involvement are emphasized. The San Diego Birth Center Study is a 4-year research project funded by the U.S. Federal Agency for Health Care Policy and Research (#R01-HS07161) to evaluate this program. The National Birth Center Study (NEJM, 1989; 321(26): 1801-11) described the advantages and safety of freestanding birth centers. However, a prospective cohort study with a concurrent comparison group of comparable risk had not been conducted on a collaborative practice-freestanding birth center model to address questions of safety, cost, and patient satisfaction.Methods: The specific aims of this study are to compare this collaborative practice model to the traditional model of perinatal health care (physician providers and hospital delivery). A prospective cohort study comparing these two health care models was conducted with a final expected sample size of approximately 2,000 birth center and 1,350 traditional care subjects. Women were recruited from both the birth center and traditional care programs (private physicians offices and hospital based clinics) at the beginning of prenatal care and followed through the end of the perinatal period. Prenatal, intrapartum, postpartum and infant morbidity and mortality are being compared along with cost-effectiveness and acceptance of the model by patients. Data collection occurred primarily through medical record abstraction with the addition of two patient questionnaires. Comparability of the cohorts was established by using a validated methodology to determine medical/perinatal risk and birth center eligibility, which included assessment by two CNMs and an independent blind review by a perinatologist. The cost analysis uses a resource-utilization approach and new methodologies such as activity-based-costing to compare costs from both the perspective of the payor and the health care provider. Patient satisfaction was measured using a self-administered patient questionnaire.Results: Current preliminary results from approximately 38% of the final expected study sample are available. Crude and adjusted analysis have been conducted. Overall, the preliminary results suggest similar morbidity and mortality in the two groups. Fetal deaths are 0.75% in the index and 0.64% in the comparison group, with early neonatal deaths at 0.26% and 0.23%, respectively. The traditional care group showed adjusted rate differences of 5.83% more major maternal intrapartum complications and 9% more NICU admissions. While the birth center group showed adjusted rate differences of 5.5% more low birth weight and 0.95% more preterm birth. For other outcomes, the birth center group showed an adjusted rate difference of 22.34% more exclusive breastfeeding at discharge. Also, there was less utilization of cesarean section and assisted delivery in the birth center group as compared to the traditional care group. The adjusted rate difference for normal spontaneous vaginal deliveries in nulliparas was 10.23% more in the birth center group, with similar results in multiparas with and without history of cesarean (28.88% and 7.84%, respectively). Preliminary results also show that the average total cost for pregnancy-related services paid by California Medicaid was $4,550 for the birth center and $5,535 for the traditional care group. Final results based on the full study sample (full data available February 1998) details of payor costs such as provider, facility, NICU, and ancillary along with costs from the health care system perspective and patient satisfaction results will be presented.Conclusion: Current results suggest similar morbidity and mortality between the birth center program and traditional care groups, with less resource utilization translating to lower costs in the collaborative practice model. Results suggest that collaborative practice using a freestanding birth center as an adjunct to an integrated perinatal health care system may provide a quality, lower-cost alternative for the provision of perinatal services.

Journal Article↗

PubMed1998

Occurrence of hemophilia in the United States. The Hemophilia Surveillance System Project Investigators.

An active surveillance system was used to identify all residents with hemophilia in six U.S. states (Colorado, Georgia, Louisiana, Massachusetts, New York, and Oklahoma). A hemophilia case was defined as a person with physician-diagnosed hemophilia A or B and/or a measured baseline factor VIII or IX activity (FA) of 30% or less. Case-finding methods included patient reports from physicians, clinical laboratories, hospitals, and hemophilia treatment centers. Once identified, trained data abstractors collected clinical and outcome data retrospectively from medical records. Among cases identified in 1993-1995, 2,743 were residents of the six states in 1994, of whom 2,156 (79%) had hemophilia A. Of those with available FA measurements, 1,140 (43%) had severe (FA < 1%), 684 (26%) had moderate (FA 1%-5%), and 848 (31%) had mild (FA 6%-30%) disease. The mean and median age was 25.4 and 23 years, respectively. The age-adjusted prevalence of hemophilia in all six states in 1994 was 13.4 cases/100,000 males (10.5 for hemophilia A and 2.9 for B). The prevalence by race/ethnicity was 13.2 cases/100,000 among white, 11.0 among African American, and 11.5 among Hispanic males. Application of age-specific prevalence rates from the six surveillance states to the U.S. population resulted in an estimated national population of 13,320 cases of hemophilia A and 3,640 cases of hemophilia B. For the 10-year period 1982-1991, the average incidence of hemophilia A and B in the hemophilia surveillance system (HSS) states was estimated to be 1 in 5,032 live male births.

Adult↗

PubMed1998

Expression of CDC2Zm and KNOTTED1 during in-vitro axillary shoot meristem proliferation and adventitious shoot meristem formation in maize (Zea mays L.) and barley (Hordeum vulgare L.).

Expression of CDC2Zm and KNOTTED1 (KN1) in maize (Zea mays L.) and their cross-reacting proteins in barley (Hordeum vulgare L.) was studied using immunolocalization during in-vitro axillary shoot meristem proliferation and adventitious shoot meristem formation. Expression of CDC2Zm, a protein involved in cell division, roughly correlated with in-vitro cell proliferation and in the meristematic domes CDC2Zm expression was triggered during in-vitro proliferation. Analysis of the expression of KN1, a protein necessary for maintenance of the shoot meristem, showed that KN1 or KN1-homologue(s) expression was retained in meristematic cells during in-vitro proliferation of axillary shoot meristems. Multiple adventitious shoot meristems appeared to form directly from the KN1- or KN1 homologue(s)-expressing meristematic cells in the invitro proliferating meristematic domes. However, unlike Arabidopsis (Arabidopsis thaliana) and tobacco (Nicotiana tabacum) leaves ectopically expressing KN1 (G. Chuck et al., 1996 Plant Cell 8: 1277-1289; N. Sinha et al., 1993 Genes Dev. 7: 787-797), transgenic maize leaves over-expressing KN1 were unable to initiate adventitious shoot meristems on their surfaces either in planta or in vitro. Therefore, expression of KN1 is not the sole triggering factor responsible for inducing adventitious shoot meristem formation from in-vitro proliferating axillary shoot meristems in maize. Our results show that genes critical to cell division and plant development have utility in defining in-vitro plant morphogenesis at the molecular level and, in combination with transformation technologies, will be powerful tools in identifying the fundamental molecular and-or genetic triggering factor(s) responsible for reprogramming of plant cells during plant morphogenesis in-vitro.

Antibodies↗

PubMed1998

The experiences of female spouses of survivors of acute myocardial infarction: a pilot study of Lebanese-born women in south-western Sydney, Australia.

Lebanese migrants form a significant proportion of the population in southwestern Sydney (SWS), and in New South Wales, Australia. This pilot study was undertaken in south-western Sydney, a rapidly expanding and socioeconomically disadvantaged region, to explore the experiences of English speaking women of Lebanese origin whose spouses had recently experienced an acute myocardial infarction (AMI). Semi-structured interviews were conducted with seven Lebanese-born women at 2- and 4-week intervals, following the discharge of their husbands from hospital. Qualitative analysis of narrative text revealed four distinct themes. These were: struggle to resolve distress; intensive monitoring of the AMI survivor; searching for avenues of support; and reflecting on the future. Study findings are discussed in relation to the literature. Implications for nursing practice and research are drawn from study findings.

Adaptation, Psychological↗

PubMed1998

Definition of T cell epitopes within the 19 kDa carboxylterminal fragment of Plasmodium yoelii merozoite surface protein 1 (MSP1(19)) and their role in immunity to malaria.

MSP1(19) is one of the leading malaria vaccine candidates. However, the mechanism of protection is not clear. To determine whether MSP1(19)-specific effector T cells can control parasitaemia, we analysed the specificity of T cells induced following immunization with recombinant forms of P. yoelii MSP1(19) and asked whether they could protect mice. There was no evidence that effector T cells were capable of protecting since: (1) immunization of mice with yMSP1(19), but not defined epitopes, was able to induce protection; and (2) long term MSP1(19)-specific CD4+ T cell lines were incapable of adoptively transferring protection. In contrast, priming mice with the T cell epitopes resulted in a rapid anamnestic antibody response to MSP1(19) after either challenge with MSP1(19) or parasite. Thus, MSP1(19) contains multiple T cell epitopes but such epitopes are the targets of helper T cells for antibody response but not of identified effector T cells capable of controlling parasitaemia.

Adoptive Transfer↗

PubMed1998

Idealised versus tainted femininity: discourses of the menstrual experience in Australian magazines that target young women.

Information and messages concerning health-related issues are not confined to material provided by official figures or sources. Much information exists in the community and comes from a variety of sources. One such source is the media. This paper reports the findings of a study conducted over a 12-month period of advertisements for menstrual products in a selection of four monthly Australian magazines (n = 48) directed towards young women. The study examined the way in which menstruation and the menstrual experience were depicted in terms of page space, textual content and visual images. Findings revealed that advertisements for menstrual products provided confusing, conflicting and paradoxical messages. These included stressing the normality of menstruation while also emphasising the importance of keeping it hidden and secret. Menstruation was depicted as being a state of tainted (idealised) femininity because of the potential for the menstrual silence to be shattered by people finding out. Protection failure was depicted as being the ultimate in tainted femininity and a result of a woman's incorrect choice of product. Choosing menstrual-care products was depicted as simple but, paradoxically, complex and confusing. Women were depicted as liberated and sophisticated but images and language related to infancy were used. Freedom and liberation were conferred by the use of the advertised product. Overall, in common with previous studies, menstruation was depicted as a crisis of hygiene that is a risk to femininity. Advertisements for pantyliners suggest that femininity itself poses a threat to (idealised) femininity. This study demonstrates the crucial role of the media as a source of health information for young women.

Adolescent↗

PubMed1998

Dose due to man-made radionuclides in terrestrial wild foods near Sellafield.

Radiological dose implications for consumers of wild foods around Sellafield have been assessed. Habits were surveyed from 72 households, mostly within a few kilometres of Sellafield. A few people were included who lived further away but collect wild foods close to Sellafield. Dose estimates were based on measured gamma emitters, as well as 239Pu, 241Am, 14C and 129I in selected samples. In all cases, doses were dominated by 137Cs. One infant was identified who consumed wild food, giving an estimated effective dose of 0.3 microSv a(-1). In the age group 2 to 10 years a mean dose of 0.51 microSv a(-1), and a maximum of 2.8 microSv a(-1), were estimated. Intakes by adults were higher and resulted in more radiologically significant doses. The extreme individual received a dose of 32 microSv a(-1) largely due to consumption of honey that included contributions from the Chernobyl accident, and hedgerow fruits. This is comparable to doses to the critical group for consumption of conventional agricultural produce close to the Sellafield site. The 97.5th percentile dose, for all age groups of consumers taken together, was 16.6 microSv a(-1), or 6.2 microSv a(-1) if the contributions from Chernobyl are excluded. Considering the contributions from different foods to the whole group of 181 wild food consumers, the rank order is honey, blackberries and venison.

Adult↗

PubMed1998

Discharges of krypton from Sellafield, 1951-1997, and the resultant doses to members of the public.

The radionulide 85Kr, which has a half-life of 10.72 years, is produced, almost exclusively, by reprocessing operations during which the fission product is released from irradiated nuclear fuel by chemical dissolution. Reprocessing plants at Sellafield, in Cumbria, have released the noble gas to atmosphere since operations commenced in 1952. Historically, krypton discharges were classified for security reasons, although these have been monitored and published by BNFL for each year since 1977. This paper reviews discharges of 85Kr from Sellafield, and consequent radiation doses, since its earliest operations. Over the past three years, discharges of 85Kr have increased due to the operation of the Thermal Oxide Fuel Reprocessing Plant (Thorp). Nonetheless, the associated annual committed effective dose to individuals remains low, peaking around 1.5 microSv a-1 to the identified critical groups, which compares with typical annual committed effective doses from natural sources of radiation of 2200 microSv. Maximum collective doses predicted from any single year of operations are 0.6 man Sv, 2 man Sv and 42 man Sv to the UK, Europe and the world respectively. Comparison may be made to natural background committed effective doses, which are of the order of 130,000 man Sva-1, 750,000 man Sva-1 and 13,000,000 man Sva-1 to the UK, EU and world populations respectively.

England↗

PubMed1998

Differential onset of median nerve block: randomized, double-blind comparison of mepivacaine and bupivacaine in healthy volunteers.

We have compared the delay in onset of 1% mepivacaine and 0.33% bupivacaine in different nerve fibre types in 10 volunteers undergoing median nerve blocks, in a randomized, double-blind, crossover study. Hot, cold, pinprick and light touch sensations, compound motor action potentials (CMAP), sensory nerve action potentials (SNAP) and skin temperature were recorded at 2-min intervals. Hot, cold, pinprick, light touch sensations, SNAP and CMAP were significantly inhibited, and skin temperature was significantly increased after administration of both agents. The first noticeable reduction in cold sensation was detected later after bupivacaine compared with mepivacaine, but after a delay similar to that of other nerve functions. Bupivacaine and mepivacaine inhibited SNAP and CMAP with a similar time delay to steady-state. Bupivacaine produced steady-state inhibition of hot and cold sensations significantly later than mepivacaine; nevertheless, the sequence that sensory modalities failed, with few exceptions, and the extent of anaesthesia at 40 min were similar for both agents. Our technique provides a novel, multi-modal method of comparing local anaesthetics and related agents over time.

Adult↗

PubMed1998

Streptococcal emm types associated with T-agglutination types and the use of conserved emm gene restriction fragment patterns for subtyping group A streptococci.

The T-agglutination types were determined for a diverse collection of 1531 group A streptococci for which the 5' M protein gene (emm) sequences had been analysed. The majority of the T-agglutination types correlated with previously seen M/emm/T-type associations; however, several new associations were found. Analysis of a subset of this collection -- which included 1157 clinical isolates with multiply encountered emm types -- found that emm amplicon restriction profiles of isolates sharing identical T types and opacity factor phenotypes are useful for detecting groups of isolates with identical emm genes. Many emm genes of known 5' sequence display a highly conserved restriction pattern amongst clinical isolates widely separated both geographically and temporally.

Agglutination↗

PubMed1998

Is the incidence of acute appendicitis really falling?

To determine if there has been a genuine fall in the incidence of acute appendicitis, an epidemiological study using HAA and Korner datasets for the years 1975-1994 was carried out to identify those children and young adults undergoing appendicectomy for acute appendicitis. The overall incidence of acute appendicitis fell from 1.84/1000 to 1.17/1000. This fall was statistically significant (R2 = 0.74, P < 0.01). The decrease was significant in both males (overall reduction, 34%) and females (overall reduction, 40%). No significant reduction was observed in either males or females between 15 and 19 years of age. The overall reduction remains essentially unexplained, but may have implications for health planning and provision of services.

Acute Disease↗

PubMed1998

Vancomycin resistant enterococcus in a hospital-based dialysis unit.

OBJECTIVE: The emergence of vancomycin resistant enterococcus (VRE) poses a serious threat to the health care community. Reservoirs of VRE are thought to exist in certain high-risk patient groups who reintroduce the organism into the hospital environment. The frequent use of vancomycin in dialysis patients may place this population at higher risk of developing VRE. This article describes the development of VRE and a point prevalence study conducted in a hospital-based dialysis unit. SETTING/SAMPLE: A dialysis unit of a tertiary care center in the eastern United States was selected as the study site. Patients who agreed to participate in the study after giving informed consent were included. Of the 85 members of this target population 33 (38.8%) agreed to participate in the study. The duration of the study was 30 days. DESIGN: After the literature was reviewed, a point prevalence study was completed at the study site. Stool samples or rectal swabs were collected from the study participants and analyzed for the presence of VRE. A chart review of patient demographic and prior treatment information was completed in order to help identify factors that correlate to the presence of VRE. METHODS: Stool or rectal swab samples were cultured on selective media and sensitivity to vancomycin was measured. RESULTS: A 9.1% prevalence of VRE was detected within the study group. The number of VRE positive subjects (3) did not allow statistically significant correlation with the demographic and prior treatment data collected. CONCLUSION: Although VRE remains a serious threat to the health care community, the prevalence of VRE within the study group does not vary markedly from rates previously reported.

Adult↗

PubMed1997

Mucosal addressin cell adhesion molecule-1 (MAdCAM-1). Its binding motif for alpha 4 beta 7 and role in experimental colitis.

The integrin alpha 4 beta 7 and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) are molecules involved in the normal recirculation of lymphocytes between the blood and the gastrointestinal tract. These molecules may play a complementary and significant role in animal models of colitis. We have investigated the structural interaction between alpha 4 beta 7 and MAdCAM-1. Site-directed mutagenesis studies of the MAdCAM-1 molecule has led to the identification of the amino acid residue (LDT) in the loop between beta strands C and D of the Ig-superfamily-like folds being involved in the adhesive and cell activation functions of MAdCAM-1 with alpha 4 beta 7.

Amino Acid Sequence↗

PubMed1997

Retrograde cerebral perfusion provides limited distribution of blood to the brain: a study in pigs.

OBJECTIVE: The objective of this study was to investigate flow distribution during retrograde and antegrade cerebral perfusion with India ink as a marker. METHODS: Ten pigs received cerebral perfusion with a solution containing 50% filtered India ink for 5 minutes either antegradely through both internal carotid arteries at a flow of 180 to 200 ml/min (n = 5) or retrogradely via the superior vena cava at a flow of 300 to 500 ml/min (n = 5). The brains were then fixed for quantitative measurement of the density of ink-filled capillaries (reported as a percentage of the total selected area). The assessment was done with the use of an in-house software program. RESULTS: In the antegrade cerebral perfusion group, the intracranial arterial and venous systems were completely filled with ink. The gray matter was colored uniformly black, and light coloring was observed in the white matter. During retrograde cerebral perfusion, the majority of ink was returned to the inferior vena cava, and only a small amount of ink was found in the innominate artery draining from the brain. Massive ink filling was observed in the sagittal sinus and other venous sinuses in all the pigs. Vessels on the surface of the brain and large vessels in the brain were also well filled with ink. However, only 10% of capillaries were filled with ink during retrograde cerebral perfusion relative to the number observed with antegrade cerebral perfusion. CONCLUSIONS: Retrograde cerebral perfusion supplies a limited amount of blood to brain tissue, which flows mainly through superficial and large deep cerebral vessels.

Animals↗