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Biomedical subjects

J Mills

Publications and source records attributed to J Mills.

At least 73 records · Page 4Linked to original sources

Review of University of British Columbia Family Practice Resident Research Projects 1990-1997.

BACKGROUND: Resident research projects can be an important component of building a strong and diversified research presence in family medicine. One of the requirements for graduation from the University of British Columbia (UBC) Family Practice Residency Program is that family practice residents complete a scholarly piece of work. METHODS: UBC family practice resident projects from 1990-1997 were reviewed and classified by methodology. A survey was sent to 251 former residents to determine 1) if their project was published, 2) if not, was there any interest in publication, and 3) what were the main reasons for not pursuing publication. Fifteen projects were selected as suitable for publication and were, with permission of the resident, submitted to medical journals. RESULTS: Sixty-nine percent of the resident projects involved data collection and hypothesis testing, and 40% were cross-sectional, of which patient surveys were the most common method. A total of 190 former residents (71%) have responded to our survey. Seven percent of respondents stated that their project had been published, and 55% would have liked to have tried to publish their project. Of the 15 resident projects we submitted for publication, seven were accepted. CONCLUSIONS: Family practice residents are capable of producing a wide variety of research projects. Only a minority of projects are being published despite the fact that the majority of residents are interested in pursuing publication. Greater assistance by faculty can increase publication of research projects.

Academic Medical Centers↗

Some clinical factors contributing to the development of the diabetic foot.

Clinical neurological studies, blood pressure measurements and some haematological investigations were performed on a random sample of forty-four patients, at the Diabetes Out-Patient Clinic of the University Hospital of the West Indies (UHWI), to examine some of the factors that predispose to the development of the diabetic foot. Our results revealed that 86% of the patients had elevated glycosylated haemoglobin (HbA1 > 9.0%), 82% had clinical signs of peripheral sensory neuropathy, 29% had signs of autonomic neuropathy in addition to peripheral sensory neuropathy. Sixty-one per cent (61%) of the patients had ankle/arm systolic blood pressure ratio less than 1.0 and were diagnosed as having peripheral vascular disease (PVD). The group with neuropathy was found to have a significantly lower diastolic blood pressure (p < 0.0005) than the group without neuropathy. We believe that hyperglycaemia-induced vasodilation (indicated by a lower diastolic blood pressure) in a significant number of diabetics resulted in compensatory shunting of blood from the deeper tissues, including nerves, to the periphery. The resulting endoneural hypoxia could be responsible for the unusually high incidence of peripheral sensory neuropathy detected in this sample of diabetic patients. Metabolic factors may also play a role.

Adult↗

A clinical approach to dental nutrition among the elderly: a description and discussion of geriatric dental nutrition.

This paper describes the role of nutrition in dentistry, especially as it relates to elderly patients. The nutritional aspects are well understood, but seldom considered in treatment plan formulation and execution, even in an academic health setting. When dental school programs are shown to have clinical relevance to a target population and are faculty supported, they are most successful. This is the case at the University of Tennessee College of Dentistry in Memphis. The role of the Nutritionist focuses on the periodontal and dental aspects of geriatric patient exposure to disease causing agents in the diet. Nutritionist, dentist, student and patient all participate in a team effort to lower patient exposures and the development of a healthful diet. In this clinical approach to geriatric patient dental nutrition, all parties contribute to the success of the whole.

Aged↗

Impaired fitness of foscarnet-resistant strains of human immunodeficiency virus type 1.

Foscarnet (PFA) is a pyrophosphate analogue antiviral active against human immunodeficiency virus (HIV-1) and herpesviruses. Strains of HIV-1 resistant to PFA have mutations in the HIV-1 reverse transcriptase (RT). We examined the influence of PFA resistance mutations, in different genetic backgrounds, on HIV-1 replication competency in both replication kinetics and growth competition assays. In replication kinetics assays, the recombinant strains HX89K, HX92I, and HX156A (encoding RT mutations E89K, L92I, and S156A, respectively, in the HXB2-D genetic background) replicated to lower titers than the wild-type parent in the absence of drug, and the degree of replication impairment increased as PFA resistance increased. PFA-resistant strains LAI 92I and LAI 156A (encoding RT mutations L92I and S156A, respectively) were replication impaired in comparison to the wild-type parent LAI to a similar degree as observed for strains in the HXB2D background. In growth competition assays with wild-type LAI, strains LAI 92I and LAI 156A had relative fitness values of 0.5 and 0.8, respectively. These results show that the RT mutations E89K, L92I and S156A, observed in PFA-resistant strains selected in cell culture, reduce replication competence. Furthermore, these data show a correlation of increasing PFA resistance and decreasing replication competence mediated by single amino acid substitutions in the RT.

Antiviral Agents↗

HIV-1 DNA and mRNA concentrations are similar in peripheral blood monocytes and alveolar macrophages in HIV-1-infected individuals.

OBJECTIVE: To determine the relative contribution of alveolar macrophages, peripheral blood monocytes (PBM) and peripheral blood lymphocytes (PBL) from HIV-infected individuals to HIV-1 viral load. METHODS: Alveolar macrophages were obtained by flexible bronchoscopy, and PBM and PBL by venipuncture from HIV-1-infected individuals. Alveolar macrophages and PBM were purified using immunomagnetic bead selection to deplete CD3+ and CD19+ cells from bronchoalveolar lavage and peripheral blood mononuclear cells, respectively. DNA and mRNA were extracted and gag copy number quantified using polymerase chain reaction (PCR) and reverse transcriptase PCR. The titres of infectious cell-associated HIV-1 in cells were determined by the endpoint dilution coculture technique for alveolar macrophages and PBM. RESULTS: Alveolar macrophages and PBM from HIV-1-infected subjects (n=11) contained equivalent concentrations of HIV-1 DNA and HIV-1 mRNA as determined by PCR and reverse transcriptase PCR, respectively. Antiretroviral therapy was associated with reduced viral DNA concentrations in alveolar macrophages but not in PBM. PBL had a significantly higher level of proviral DNA and mRNA than alveolar macrophages or PBM. CONCLUSIONS: Although alveolar macrophages infected in vitro are more permissive for HIV-1 replication than PBM, this difference could not be demonstrated in vivo.

Cells, Cultured↗

Serological detection of attenuated HIV-1 variants with nef gene deletions.

OBJECTIVE: To investigate whether members of a transfusion-linked cohort (the Sydney Bloodbank Cohort) infected with a nef-deleted strain of HIV-1 could be differentiated from individuals infected with wild-type strains of HIV-1 by characterizing the Nef antibody response of cohort members. DESIGN: Retrospective and prospective analysis of the nef gene sequence and the antibody response to Nef peptides in HIV-infected subjects. METHODS: Plasma was obtained from all individuals of the Sydney cohort, and from a variety of HIV-1-infected and uninfected controls. Antibodies recognizing full-length recombinant HIV-1NL43 Nef protein and synthetic peptide analogues were assessed by enzyme-linked immunosorbent assay. RESULTS: All 34 individuals infected with wild-type HIV-1 had antibodies reacting with full-length Nef protein as well as with a series of synthetic peptides (6-23-mers) spanning most of the Nef protein of HIV-1NL43. Although the HIV-1 quasispecies infecting the Sydney cohort had a consensus deletion of the nef gene corresponding to amino-acids 165-206, HIV-1 strains from individual members of the cohort had additional deletions comprising up to 80% of the nef gene. Members of the cohort had antibodies to peptides homologous to all regions of the Nef protein tested, except for a single peptide (amino-acids 162-177) that lies within the consensus nef deletion for the cohort quasispecies. CONCLUSION: These data show that nef-deleted strains of HIV-1 can be detected serologically. In the Sydney cohort, detection of antibodies to all regions of Nef tested, except that corresponding to amino-acids 162-177, suggests that observed deletions outside this domain occurred after this virus had infected these subjects and stimulated an immune response. A Nef peptide serological assay may be useful for identifying further examples of individuals infected with nef-deleted, attenuated HIV-1 quasispecies and for assessing the evolution of those variants in vivo.

AIDS Serodiagnosis↗

Characterisation of a binding-protein-dependent, active transport system for short-chain amides and urea in the methylotrophic bacterium Methylophilus methylotrophus.

Three genes (fmdCAB) encoding an outer-membrane porin for short-chain amides and urea, formamidase, and a putative regulatory protein in Methylophilus methylotrophus have previously been cloned and characterised. Three genes have now been identified downstream of fmdB, viz fmdD encoding a hydrophilic protein containing an N-terminal signal sequence, and fmdEF encoding hydrophobic transmembrane proteins. The derived amino acid sequence of mature FmdD (predicted molecular mass 41,870 Da) was similar to the cytoplasmic, amide-binding protein (AmiC) from Pseudomonas aeruginosa and to several periplasmic, solute-binding proteins from other bacteria. Mature FmdD was purified and shown to be a monomer (40-45 kDa) with the predicted N-terminal amino acid sequence (ADYPTA-). Equilibrium dialysis showed that the purified protein bound short-chain amides and urea with high affinity (Kd 7.2 microM for [14C]urea). SDS/PAGE and western blotting using antiserum to mature FmdD showed it was induced by short-chain amides and urea, and repressed by excess ammonia. The derived amino acid sequences of FmdE (32,822 Da) and FmdF (incomplete; >25,435 Da) were similar to the transmembrane proteins BraD/LivH and BraE/LivM, respectively, in various leucine/isoleucine/valine transport systems. Uptake of [14C]urea by washed cells was inhibited by the uncoupling agent carbonyl cyanide p-trifluoromethoxyphenylhydrazone and unlabelled formamide. It is concluded that FmdDEF comprise part of a high-affinity, binding-protein-dependent active-transport system for short-chain amides and urea in M. methylotrophus.

Amides↗

Sexually dimorphic responses to neonatal basal forebrain lesions in mice: I. Behavior and neurochemistry.

The nucleus basalis magnocellularis (nBM) provides the primary source of cholinergic input to the cortex. Neonatal lesions of the nBM produce transient reductions in cholinergic markers, persistent abnormalities in cortical morphology, and spatial navigation impairments in adult mice. The present study examined sex differences in the effects of an electrolytic nBM lesion on postnatal day 1 (PND 1) in mice on behavior and neurochemistry in adulthood. Mice were lesioned on PND 1 and tested at 8 weeks of age on a battery of behavioral tests including passive avoidance, cued and spatial tasks in the Morris water maze, simple and delayed nonmatch to sample versions of an odor discrimination task, and locomotor activity measurements. Following behavioral testing, mice were sacrificed for either morphological assessment or neurochemical analysis of a cholinergic marker or catecholamines. There were no lesion or sex differences in acquisition or retention of passive avoidance, performance of the odor discrimination tasks, or activity levels. Control mice showed a robust sex difference in performance of the spatial water maze task. The lesion produced a slight cued but more dramatic spatial navigation deficit in the water maze which affected only the male mice. Neurochemical analyses revealed no lesion-induced changes in either choline acetyltransferase activity or levels of norepinephrine or serotonin at the time of testing. The subsequent report shows a sex difference in lesion-induced changes in cortical morphology which suggests that sexually dimorphic cholinergic influences on cortical development are responsible for the behavioral deficits seen in this study.

Aging↗

Antagonism of the IL-6 cytokine subfamily--a potential strategy for more effective therapy in rheumatoid arthritis.

Pro-inflammatory cytokines, some of which have the capacity to modulate cartilage and bone metabolism, are important mediators of the frequently sustained and destructive inflammation that characterises rheumatoid arthritis (RA). Tumour necrosis factor alpha (TNF alpha) and interleukin-1 (IL-1) have been studied extensively in this regard. That these proteins are important is no longer in doubt following the demonstration that the IL-1 receptor antagonist and neutralising antibodies directed against TNF alpha are clinically effective. Recent studies suggest that interleukin-6 (IL-6) and other members of the IL-6 cytokine subfamily are also potentially important cytokines in the pathogenesis of RA. The recognition of shared molecular subunits in the receptors for these cytokines raises the possibility that components of these receptors or their derivatives, either alone or in combination, may be useful for antagonising members of the IL-6 cytokine subfamily. Effective antagonism could be therapeutically beneficial in respect to attenuating inflammation and protecting critically important chondral and skeletal tissue. In this review the rationale and possible strategies for such antagonism are discussed.

Animals↗

Interactions between poly(2-ethylacrylic acid) and lipid bilayer membranes: effects of cholesterol and grafted poly(ethylene glycol).

The exchange of the protonatable polymer, poly(2-ethylacrylic acid) (PEAA), has been studied with vesicle membranes containing cholesterol from 0 to 60 mol% or PEG2000-lipid (5 mol%). The release of an entrapped dye from 100 nm extruded liposomes was used as an assay for membrane perturbation by the polymer as a function of pH. The inclusion of cholesterol was found to reduce the pH at which the polymer caused release of the dye from the lipid vesicles, and the degree of polymer protonation (i.e., degree of hydrophobicity) correlated well with the increase in elastic expansion modulus of the vesicle bilayer. The results are discussed in terms of a balance between polymer solubility and membrane expansion. With respect to the PEG barrier, the presence of 5 mol% PEG2000, which represents full surface coverage, did not prevent PEAA from inducing contents release, demonstrating that highly hydrated polymeric layers are not effective barriers for other water soluble polymers, and may point to some association between the two polymers.

Acrylates↗

Coresistance to zidovudine and foscarnet is associated with multiple mutations in the human immunodeficiency virus type 1 reverse transcriptase.

Human immunodeficiency virus type 1 (HIV-1) isolates obtained from a patient with AIDS were assessed for coresistance to foscarnet and zidovudine. An HIV-1 strain (AP20) coresistant to foscarnet and zidovudine was isolated after 20 months of continuous combination therapy. The reverse transcriptase (RT) gene of AP20 had 41 substitutions which were different from the HXB2-D sequence and 9 that were different from the sequence of its foscarnet-sensitive, zidovudine-resistant progenitor virus (AP6). Six of these mutations were nonpolymorphic (T39A, V108I, K166R, K219R, K223Q, and L228R). Both strains had the conventional mutations mediating zidovudine resistance. In vivo selection may result in HIV-1 strains that are coresistant to foscarnet and zidovudine, but coresistance appears to require a complex evolutionary path and multiple RT mutations.

Amino Acid Sequence↗

Measures of independent variables and mediators are useful in social psychology experiments: but are they necessary?

A study of experiments in major social psychology journals shows that measures of independent variables have become increasingly common. The role in experiments of measures of independent variables and proposed mediating variables is examined. In the causal sequence assumed in interpreting an experimental result, the independent variable and proposed mediating variable are presumed to mediate the effect of the experimental treatment on the dependent measure. Measures of independent variables and mediators provide checks on the assumptions that the experimental treatment successfully manipulated those variables and are unquestionably useful. A separate, controversial issue is whether such measures are necessary in experiments. If no plausible alternative explanations exist, data from such measures are not needed. Plausible alternative explanations are not eliminated by data from such measures. Alternative explanations, critical for assessing construct validity (Cook & Campbell, 1979), are distinguished from different general theoretical accounts of a finding.

Journal Article↗

Radiosensitive human tumour cell lines show misrepair of DNA termini.

Physical measures of the rejoining of radiation-induced breaks in DNA strands are limited in terms of sensitivity and the fact that they do not assess the fidelity with which the rejoining occurs. In this report, transfection of cleaved plasmid has been used as a probe for repair in three radiosensitive tumour cell lines and shown them to have low repair fidelity compared with resistant cells. Errors in the repair of linear plasmid were found by Southern analysis, in keeping with the measured repair fidelity. Radiosensitive tumour cells showed few errors in the uptake and integration of circular plasmid, in contrast to ataxia-telangiectasia (A-T) cells. In the neuroblastoma HX142, the repair of blunt-ended linear plasmid was associated with deletions of > 1 kb; staggered-ended linear plasmid was repaired with small insertions and circular plasmid integration was intact in > 60% of the copies. The neuroblastoma SKN.SH, processed staggered-ended plasmid by insertions of a variety of sizes, but processed circular plasmid largely error-free. In contrast, A-T cells (AT5BIVA) had the same spectrum of errors irrespective of the form of plasmid transfected. Cell fusion between HX142 and AT5BIVA showed complementation to a resistant phenotype, suggesting that misrepair in the tumour cell did not result from somatic mutation in the ATM gene. In conclusion, radiosensitive tumours show evidence of misrepair of DNA termini, with a mechanism which is functionally and genetically distinct from that in A-T cells.

Ataxia Telangiectasia↗

Regulation of amyloid precursor protein catabolism involves the mitogen-activated protein kinase signal transduction pathway.

Catabolic processing of the amyloid precursor protein (APP) is subject to regulatory control by protein kinases. We hypothesized that this regulation involves sequential activation of the enzymes mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated protein kinase (ERK). In the present investigation, we provide evidence that MEK is critically involved in regulating APP processing by both nerve growth factor and phorbol esters. Western blot analysis of the soluble N-terminal APP derivative APPs demonstrated that the synthetic MEK inhibitor PD 98059 antagonized nerve growth factor stimulation of both APPs production and ERK activation in PC12 cells. Moreover, PD 98059 inhibited phorbol ester stimulation of APPs production and activation of ERK in both human embryonic kidney cells and cortical neurons. Furthermore, overexpression of a kinase-inactive MEK mutant inhibited phorbol ester stimulation of APP secretion and activation of ERK in human embryonic kidney cell lines. Most important, PD 98059 antagonized phorbol ester-mediated inhibition of Abeta secretion from cells overexpressing human APP695 carrying the "Swedish mutation." Taken together, these data indicate that MEK and ERK may be critically involved in protein kinase C and nerve growth factor regulation of APP processing. The mitogen-activated protein kinase cascade may provide a novel target for altering catabolic processing of APP.

Alzheimer Disease↗

Determination of the disulfide bond arrangement of human respiratory syncytial virus attachment (G) protein by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The attachment protein or G protein of the A2 strain of human respiratory syncytial virus (RSV) was digested with trypsin and the resultant peptides separated by reverse-phase high-performance liquid chromatography (HPLC). One tryptic peptide produced a mass by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) corresponding to residues 152-187 with the four Cys residues of the ectodomain (residues 173, 176, 182, and 186) in disulfide linkage and absence of glycosylation. Sub-digestion of this tryptic peptide with pepsin and thermolysin produced peptides consistent with disulfide bonds between Cys173 and Cys186 and between Cys176 and Cys182. Analysis of ions produced by post-source decay of a peptic peptide during MALDI-TOF-MS revealed fragmentation of peptide bonds with minimal fission of an inter-chain disulfide bond. Ions produced by this unprecedented MALDI-induced post-source fragmentation corroborated the existence of the disulfide arrangement deduced from mass analysis of proteolysis products. These findings indicate that the ectodomain of the G protein has a non-glycosylated subdomain containing a "cystine noose."

Amino Acid Sequence↗

Electromyographic assessment of biofeedback training for fecal incontinence and chronic constipation.

INTRODUCTION: Biofeedback training is an effective modality for the treatment of chronic constipation and fecal incontinence. In general, patients express satisfaction and perceive functional improvement following biofeedback therapy; however, quantifying these observations has been difficult. AIM: This study was undertaken to evaluate the physiologic benefits of biofeedback therapy as reflected by noninvasive electromyography parameters. METHODS: Fifty-five patients who underwent computerized electromyography-based biofeedback treatment at our institution between July 1993 and July 1995 were identified. Noninvasive electromyographic testing was performed before, during (weekly), and at completion of training. Mean number of weekly sessions was seven (range, 5-11). Short-term and ten-second contractions (amplitude/microV), sustained contractions (endurance, in seconds), and net strength (microV) of the external anal sphincter before and after biofeedback were compared for differences. RESULTS: There were 30 patients with chronic constipation, mean age, 65.3 (range, 33-86) years, composed of 24 women, and 25 patients with fecal incontinence, mean age 66 (range, 34-85) years, composed of 12 males. Statistically significant improvement in endurance and net strength following biofeedback training was noted in both the constipated and the fecal incontinence groups. Fifty-three of 55 (96.4 percent) patients expressed 50 to 100 percent subjective satisfaction after biofeedback therapy. Forty-six of 55 (83.6 percent) patients demonstrated individually improved endurance. CONCLUSIONS: Sphincter endurance and net strength, as measured by noninvasive electromyography, significantly improve following biofeedback therapy in both constipated and fecal incontinence patients. These data suggest that endurance and net strength may be useful tools in assessing a benefit from biofeedback training in these patients.

Adult↗