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Biomedical subjects

K Hardy

Publications and source records attributed to K Hardy.

At least 19 recordsLinked to original sources
PubMed2006

Insulin glargine or NPH combined with metformin in type 2 diabetes: the LANMET study.

AIMS/HYPOTHESIS: In type 2 diabetic patients we compared 9 months of combination therapy with insulin glargine and metformin with 9 months of NPH insulin combined with metformin. The primary focus was changes in HbA(1c); secondary focus was diurnal glucose profiles and symptomatic hypoglycaemia. METHODS: In this investigator-initiated open, parallel-group clinical trial involving seven centres, 110 insulin-naive type 2 diabetic patients with poor glycaemic control (HbA(1c) >or=8.0%) on oral hypoglycaemic agents (90% using sulfonylurea plus metformin) were randomised to receive bedtime insulin glargine with metformin (G+MET) or bedtime NPH with metformin (NPH+MET) for 36 weeks. The patients were taught how to self-adjust their insulin dose and use a modem to send the results of home glucose monitoring to treatment centres. The goal was to achieve a fasting plasma glucose (FPG) of 4.0 to 5.5 mmol/l in both groups. RESULTS: During the last 12 weeks, FPGs averaged 5.75+/-0.02 and 5.96+/-0.03 mmol/l (p<0.001) and insulin doses were 68+/-5 and 70+/-6 IU/day (0.69+/-0.05 and 0.66+/-0.04 IU kg(-1) day(-1), NS) in the G+MET and NPH+MET groups, respectively. At 36 weeks, mean HbA(1c) was 7.14+/-0.12 and 7.16+/-0.14%, respectively (NS). Symptomatic, but not confirmed symptomatic, hypoglycaemia was significantly lower during the first 12 weeks in the G+MET group (4.1+/-0.8 episodes/patient-year) than in the NPH+MET group (9.0+/-2.3 episodes/patient-year, p<0.05), but not significantly different thereafter. Glucose levels before dinner were higher in the NPH+MET group (10.1+/-0.3 mmol/l) than in the G+MET group (8.6+/-0.3 mmol/l, p=0.002) throughout the 36-week study. With regard to baseline characteristics such as initial glycaemia or C-peptide, there was no difference between patients who achieved good glycaemic control (HbA(1c) <7.0%) and those who did not. Differences were seen in the following: between study centres, weight gain during the run-in period and insulin therapy, and FPG during the last 12 weeks (5.7+/-0.2 vs 6.7+/-0.3 mmol/l for patients reaching vs those not reaching target, p<0.01). CONCLUSIONS/INTERPRETATION: Good glycaemic control can be achieved with both G+MET and NPH+MET. Use of G+MET reduces symptomatic hypoglycaemia during the first 12 weeks and dinner time hyperglycaemia compared with NPH+MET.

Adult↗
PubMed2006

Activators of viral gene expression in polarized epithelial monolayers identified by rapid-throughput drug screening.

Epithelial polarity and tight junction formation limit the ability of adenovirus, retrovirus and adeno-associated virus (AAV) to deliver and express virally encoded genes. Using an extended half-life luciferase assay and high-throughput luminometry, we screened 23 000 compounds and natural product extracts as potentiators to overcome this barrier. Seven strong activators were discovered (up to several hundred fold above control) and two of these exhibited spectrum of activity in multiple cell types (HeLa (human cervical carcinoma), cystic fibrosis bronchial epithelial (human bronchial), HT29 (human colonic carcinoma), Calu3 (airway serous glandular)). Enhanced transduction by unrelated gene transfer vectors (adenovirus, lentivirus, AAV, liposomal) was also observed. These results establish a strategy for identifying compounds that improve viral gene transfer to resistant cell types, and provide new tools for examining epithelial defense against viral infection. The compounds should have broad usefulness in experimental therapies for cancer and genetic diseases.

Adenoviridae↗
PubMed2006

Closing the water loop in a maltery: reuse tests at pilot-scale.

This paper reports on the potential for water reuse in the malting sector. Core unit of a treatment train to close the water loop was a membrane bioreactor (MBR). We compared three different commercial submerged membranes for their fouling potential in this application and related this to the presence of extracellular polymeric substances (EPS). In a second step, we subjected MBR permeate to reverse osmosis and several (advanced) oxidation processes to evaluate the water quality achieved. Finally we performed a set of water reuse tests with waters obtained through different scenarios. The optimal scenario was then tested in a closed water loop over several malting cycles at pilot scale and the effect on water and malt quality was investigated.

Bioreactors↗
PubMed2004

Transcriptional networks and cellular senescence in human mammary fibroblasts.

Senescence, the molecular program that limits the finite proliferative potential of a cell, acts as an important barrier to protect the body from cancer. Techniques for measuring transcriptome changes and for modulating their expression suggest that it may be possible to dissect the transcriptional networks underlying complex cellular processes. HMF3A cells are conditionally immortalized human mammary fibroblasts that can be induced to undergo coordinated senescence. Here, we used these cells in conjunction with microarrays, RNA interference, and in silico promoter analysis to promote the dissection of the transcriptional networks responsible for regulating cellular senescence. We first identified changes in the transcriptome when HMF3A cells undergo senescence and then compared them with those observed upon replicative senescence in primary human mammary fibroblasts. In addition to DUSP1 and known p53 and E2F targets, a number of genes such as PHLDA1, NR4A3, and a novel splice variant of STAC were implicated in senescence. Their role in senescence was then analyzed by RNA silencing followed by microarray analysis. In silico promoter analysis of all differential genes predicted that nuclear factor-kappaB and C/EBP transcription factors are activated upon senescence, and we confirmed this by electrophoretic mobility shift assay. The results suggest a putative signaling network for cellular senescence.

Cell Cycle Proteins↗
PubMed2004

Impaired insulin-dependent glucose metabolism in granulosa-lutein cells from anovulatory women with polycystic ovaries.

BACKGROUND: Insulin resistance and hyperinsulinaemia are well-recognized characteristics of anovulatory women with polycystic ovary syndrome (PCOS) but, paradoxically, steroidogenesis by PCOS granulosa cells remains responsive to insulin. The hypothesis to be tested in this study is that insulin resistance in the ovary is confined to the metabolic effects of insulin (i.e. glucose uptake and metabolism), whereas the steroidogenic action of insulin remains intact. METHODS: Granulosa-lutein cells were obtained during IVF cycles from seven women with normal ovaries, six ovulatory women with PCO (ovPCO) and seven anovulatory women with PCO (anovPCO). Mean body mass index was in the normal range in all three groups. Granulosa-lutein cells were cultured with insulin (1, 10, 100 and 1000 ng/ml) and LH (1, 2.5 and 5 ng/ml). Media were sampled at 24 and 48 h and analysed for glucose uptake, lactate production and (48 h only) progesterone production. RESULTS: Insulin-stimulated glucose uptake by cells from anovPCO was attenuated at higher doses of insulin (100 and 1000 ng/ml) compared with that by cells from either ovPCO (P=0.02) or controls (P=0.02). Insulin and LH stimulated lactate production in a dose-dependent manner, but insulin-dependent lactate production was markedly impaired in granulosa-lutein cells from anovPCO compared with either normal (P=0.002) or ovPCO (P<0.0001). By contrast, there was no difference in insulin-stimulated progesterone production between granulosa-lutein cells from the three ovarian types. CONCLUSIONS: Granulosa-lutein cells from women with anovPCOS are relatively resistant to the effects of insulin-stimulated glucose uptake and utilization compared with those from normal and ovPCO, whilst maintaining normal steroidogenic output in response to physiological doses of insulin. These studies support the probability of a post-receptor, signalling pathway-specific impairment of insulin action in PCOS.

Adult↗
PubMed2004

[The risk of thromboembolism in airline passengers].

Long carrier flights favor thromboembolism. The risk is well known to the general public but is probably really very low. The risk is however pertinent due to the volume of air travel in the world. Sitting in the same position for a long time induced venous stasis which is the principal factor favoring thrombosis in travelers, irrespective of the means of transportation. Long carrier flights also expose passengers to specific factors related to air travel: coagulation disorders and alterations of the endothelium related to hypobarism, hypoxia and low hygrometry in the cabin. Presence of pathogenic thrombophilia is not a constant factor. The prevention of venous thrombosis in air travelers calls upon simple measures: abundant hydration, avoiding use of alcohol and tobacco, walking and dorsal flexion of the feet. The only preventive option with proven efficacy is the use of elastic contention which reduces the risk of thromboembolic events. There is no consensus concerning the use of drugs proposed by certain authors; prudence should be the rule. All passengers should become aware of the risk of thromboembolism related to sitting in the same position for a long time.

Aerospace Medicine↗
PubMed2004

Preimplantation genetic diagnosis of spinocerebellar ataxia 3 by (CAG)(n) repeat detection.

Spinocerebellar ataxia 3 (SCA3) is an autosomal dominant neurodegenerative disorder characterized by variable expression and a variable age of onset. SCA3/MJD (Machado-Joseph disease) is caused by an expansion of a (CAG)(n) repeat in the MJD1 gene on chromosome 14q32.1. A single cell PCR protocol has been developed for preimplantation genetic diagnosis (PGD) of SCA3 to select unaffected embryos on the basis of the CAG genotype. Single leukocytes and blastomeres served as a single cell amplification test system to determine the percentage of allelic drop-out (ADO) and PCR efficiency. Out of 105 tested heterozygous single leukocytes, 103 (98.1%) showed a positive amplification signal, while five cells (4.9%) showed ADO. Amplification in single blastomeres was obtained in 13 out of a total of 14, and ADO was observed in two out of the 13 single blastomeres. PGD of SCA3 was performed in a couple with paternal transmission of the SCA3 allele. Seven embryos were available for biopsy, all biopsied blastomeres showed amplification and no ADO occurred. One embryo was diagnosed as affected whereas six embryos were diagnosed as unaffected. Two unaffected embryos were transferred and resulted in a singleton pregnancy and the birth of a healthy girl.

Alleles↗
PubMed2003

Formation and early development of follicles in the polycystic ovary.

BACKGROUND: Polycystic ovary syndrome is the most common cause of anovulatory infertility. It has long-term health implications and is an important risk factor for type 2 diabetes. However, little is known about the cause of polycystic ovaries. We have used detailed morphological analysis to assess the hypothesis that there is an intrinsic ovarian abnormality that affects the earliest stages of follicular development. METHODS: We took small cortical biopsies during routine laparoscopy from 24 women with normal ovaries and regular cycles and from 32 women with polycystic ovaries, 16 of whom had regular, ovulatory cycles and 16 of whom had oligomenorrhoea. We used computerised image analysis to assess the density and developmental stage of small preantral follicles in serial sections of fixed tissue. FINDINGS: Median density of small preantral follicles, including those at primordial and primary stages, was six-fold greater in biopsies from polycystic ovaries in anovulatory women than in normal ovaries (p=0.009). In both ovulatory and anovulatory women with polycystic ovaries, we noted a significant increase in the percentage of early growing (primary) follicles and a reciprocal decrease in the proportion of primordial follicles compared with normal ovaries. INTERPRETATION: Our findings indicate that there are fundamental differences between polycystic and normal ovaries in early follicular development, suggesting an intrinsic ovarian abnormality. The increased density of small preantral follicles in polycystic ovaries could result from increased population of the fetal ovary by germ cells, or from decreased rate of loss of oocytes during late gestation, childhood, and puberty.

Adult↗
PubMed2002

Mathematical models of the balance between apoptosis and proliferation.

As our understanding of cellular behaviour grows, and we identify more and more genes involved in the control of such basic processes as cell division and programmed cell death, it becomes increasingly difficult to integrate such detailed knowledge into a meaningful whole. This is an area where mathematical modelling can complement experimental approaches, and even simple mathematical models can yield useful biological insights. This review presents examples of this in the context of understanding the combined effects of different levels of cell death and cell division in a number of biological systems including tumour growth, the homeostasis of immune memory and pre-implantation embryo development. The models we describe, although simplistic, yield insight into several phenomena that are difficult to understand using a purely experimental approach. This includes the different roles played by the apoptosis of stem cells and differentiated cells in determining whether or not a tumour can grow; the way in which a density dependent rate of apoptosis (for instance mediated by cell-cell contact or cytokine signalling) can lead to homeostasis; and the effect of stochastic fluctuations when the number of cells involved is small. We also highlight how models can maximize the amount of information that can be extracted from limited experimental data. The review concludes by summarizing the various mathematical frameworks that can be used to develop new models and the type of biological information that is required to do this.

Apoptosis↗
PubMed2002

Modulation of A(beta) peptides by estrogen in mouse models.

Clinical studies have shown that estrogen deprivation through menopause is a risk factor in both the initiation and progression of Alzheimer's disease (AD) and that estrogen replacement therapy may be protective. One of the major pathological features in the human AD brain is the senile plaque, a proteinaceous structure composed mainly of heterogeneous peptides collectively known as A-beta (A(beta)). In vitro studies have linked estrogen with A(beta) modulation, suggesting that one-way that estrogen depletion at menopause may exacerbate the features of AD is through A(beta) accumulation. To test this, two studies were performed on transgenic models of amyloidosis. Firstly, transgenic mice without detectable amyloid aggregates were subjected to ovariectomy and estradiol supplementation, and A(beta) levels were assessed. Secondly, the effects of estrogen modulation were assessed in mice at an age when plaques would be forming initially. Overall, A(beta) levels were higher in estrogen-deprived mice than intact mice, and this effect could be reversed through the administration of estradiol. These data suggest that, in vivo, estrogen depletion leads to the accumulation of A(beta) in the CNS, which can be reversed through replacement of estradiol. These results provide evidence that post-menopausal estrogen depletion may be linked to an increased risk of AD through A(beta) modulation.

Amyloid beta-Peptides↗
PubMed2002

Assessing patients' preferences for characteristics associated with homeopathic and conventional treatment of asthma: a conjoint analysis study.

BACKGROUND: A study was undertaken to investigate the preferences of patients with asthma for attributes or characteristics associated with treatment for their asthma and to investigate the extent to which such preferences may differ between patient subgroups. METHODS: The economic technique of conjoint analysis (CA) was used to investigate patients' strength of preference for several key attributes associated with services for the treatment of asthma. A CA questionnaire was administered to two groups of asthma outpatients aged 18 years or older, 150 receiving conventional treatment at Whipps Cross Hospital (WC) and 150 receiving homeopathic treatment at the Royal London Homoeopathic Hospital (RL). RESULTS: An overall response rate of 47% (n=142) was achieved. Statistically significant attributes in influencing preferences for both the WC and RL respondents were (1) the extent to which the doctor gave sufficient time to listen to what the patient has to say, (2) the extent to which the treatment seemed to relieve symptoms, and (3) the travel costs of attending for an asthma consultation. The extent to which the doctor treated the patient as a whole person was also a statistically significant attribute for the RL respondents. CONCLUSIONS: This study has shown that aspects associated with the process of delivery of asthma services are important to patients in addition to treatment outcomes. The homeopathic respondents expressed stronger preferences for the doctor to treat them as a whole person than the patients receiving conventional treatment. Overall, the preferences for the attributes included in the study were similar for both groups.

Adult↗
PubMed2002

Caspase activity and expression of cell death genes during development of human preimplantation embryos.

It has been observed that apoptosis occurs in human blastocysts. In other types of cell, the characteristic morphological changes seen in apoptotic cells are executed by caspases, which are regulated by the BCL-2 family of proteins. This study investigated whether these components of the apoptotic cascade are present throughout human preimplantation development. Developing and arrested two pronucleate embryos at all stages were incubated with a fluorescently tagged caspase inhibitor that binds only to active caspases, fixed, counterstained with 4,6-diamidino-2-phenylindole (DAPI) to assess nuclear morphology and examined using confocal microscopy. Active caspases were detected only after compaction, at the morula and blastocyst stages, and were frequently associated with apoptotic nuclei. Occasional labelling was seen in arrested embryos. Expression of proapoptotic BAX and BAD and anti-apoptotic BCL-2 was examined in single embryos using RT-PCR and immunohistochemistry. BAX and BCL-2 mRNAs were expressed throughout development, whereas BAD mRNA was expressed mainly after compaction. Simultaneous expression of BAX and BCL-2 proteins within individual embryos was confirmed using immunohistochemistry. The onset of caspase activity and BAD expression after compaction correlates with the previously reported appearance of apoptotic nuclei. As in other types of cell, human embryos express common molecular components of the apoptotic cascade, although apoptosis appears to be suppressed before compaction and differentiation.

Apoptosis↗
PubMed2002

Growth factor expression and function in the human and mouse preimplantation embryo.

There is increasing evidence that even before implantation, human development is regulated by embryonically and maternally derived growth factors. Studies in other mammalian species have shown that growth factors and their receptors are expressed by the preimplantation embryo and the reproductive tract. Furthermore, a number of growth factors have been shown to affect rate of embryo development, the proportion of embryos developing to the blastocyst stage, blastocyst cell number, metabolism and apoptosis. Growth factor ligands and receptors are also expressed in human embryos and the maternal reproductive tract, and supplementation of culture medium with exogenous growth factors affects cell fate, development and metabolism of human embryos in vitro. Autocrine, paracrine and endocrine pathways that may operate within the embryo and between the embryo and the reproductive tract before implantation are proposed.

Animals↗
PubMed2001

From cell death to embryo arrest: mathematical models of human preimplantation embryo development.

Human preimplantation embryos exhibit high levels of apoptotic cells and high rates of developmental arrest during the first week in vitro. The relation between the two is unclear and difficult to determine by conventional experimental approaches, partly because of limited numbers of embryos. We apply a mixture of experiment and mathematical modeling to show that observed levels of cell death can be reconciled with the high levels of embryo arrest seen in the human only if the developmental competence of embryos is already established at the zygote stage, and environmental factors merely modulate this. This suggests that research on improving in vitro fertilization success rates should move from its current concentration on optimizing culture media to focus more on the generation of a healthy zygote and on understanding the mechanisms that cause chromosomal and other abnormalities during early cleavage stages.

Apoptosis↗
PubMed2001

Amino acids promote human blastocyst development in vitro.

Supplementation of culture media with amino acids has been shown to benefit preimplantation embryo development in several species. This randomized study analysed the in-vitro development of human embryos obtained after IVF in the presence or absence of a combination of amino acids from the 2- to 4-cell stage to the blastocyst stage. A total of 129 human embryos was randomly distributed between three serum-free chemically defined sequential media: (i) glucose-free Earle's balanced salt solution (EBSS) with glutamine (Gln) prior to morula stage, supplemented with glucose for blastocyst formation; (ii) glucose-free EBSS with glutamine and non-essential amino acids (AA) for cleavage stage development, and supplemented with all 20 AA for blastocyst formation (Earle's+AA); and (iii) a sequential commercial medium containing amino acids (K-SCIM). Embryos were individually cultured for successive periods of 24 h. On day 6 of development, blastocysts were differentially labelled and the numbers of trophectoderm and inner cell mass cells, mitoses and dead cells were examined. Blastocyst development was similar for the three sequential media. The mixture of AA significantly increased total blastocyst cell numbers from 61.8 +/- 4.2 with Earle's+Gln to 99.3 +/- 8.4 with Earle's+AA and 100.2 +/- 9.4 with K-SCIM (P = 0.005). This increase was present in both the trophectoderm and inner cell mass lineages (P < 0.02). Furthermore, the dead cell index was significantly lower with Earle's+AA (P = 0.047).

Amino Acids↗
PubMed2001

Mathematical model of FSH-induced cAMP production in ovarian follicles.

During the terminal part of their development, ovarian follicles become totally dependent on gonadotropin supply to pursue their growth and maturation. Both gonadotropins, follicle-stimulating hormone (FSH) and luteining hormone (LH), operate mainly through stimulatory G protein-coupled receptors, their signal being transduced by the activation of the enzyme adenylyl cyclase and the production of second-messenger cAMP. In this paper, we develop a mathematical model of the dynamics of the coupling between FSH receptor stimulation and cAMP synthesis. This model takes the form of a set of nonlinear, ordinary differential equations that describe the changes in the different states of FSH receptors (free, bound, phosphorylated, and internalized), coupling efficiency (activated adenylyl cyclase), and cAMP response. Classical analysis shows that, in the case of constant FSH signal input, the system converges to a unique, stable equilibrium state, whose properties are here investigated. The system also appears to be robust to nonconstant input. Particular attention is given to the influence of biologically relevant parameters on cAMP dynamics.

Algorithms↗
PubMed2001

Bilateral phrenic paralysis in a patient with systemic lupus erythematosus.

Respiratory manifestations of systemic lupus erythematosus (SLE) are frequent. They include respiratory muscle abnormalities, which have been implicated in the pathogenesis of the "shrinking lung syndrome" (SLS). We report the case of a patient with this syndrome, in whom diaphragmatic paralysis due to demyelinating phrenic lesions was diagnosed at the same time as SLE. Follow-up studies showed a favorable clinical and diaphragmatic outcome with corticosteroid therapy, but little change in spirometry. It is concluded that severe diaphragm palsy is possibly due to phrenic nerve lesions in SLE, and that the link between diaphragm dysfunction and the SLS is probably not a straightforward one.

Adult↗