Biomedical subjects
Publications and source records attributed to M Williams.
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Emerging data suggest that a subset of circulating human CD34(+) cells have phenotypic features of endothelial cells. Whether these cells are sloughed mature endothelial cells or functional circulating endothelial precursors (CEPs) is not known. Using monoclonal antibodies (MoAbs) to the extracellular domain of the human vascular endothelial receptor-2 (VEGFR-2), we have shown that 1.2 +/- 0.3% of CD34(+) cells isolated from fetal liver (FL), 2 +/- 0.5% from mobilized peripheral blood, and 1.4 +/- 0.5% from cord blood were VEGFR-2(+). In addition, most CD34(+)VEGFR-2(+) cells express hematopoietic stem cell marker AC133. Because mature endothelial cells do not express AC133, coexpression of VEGFR-2 and AC133 on CD34(+) cells phenotypically identifies a unique population of CEPs. CD34(+)VEGFR-2(+) cells express endothelial-specific markers, including VE-cadherin and E-selectin. Also, virtually all CD34(+)VEGFR-2(+) cells express the chemokine receptor CXCR4 and migrate in response to stromal-derived factor (SDF)-1 or VEGF. To quantitate the plating efficiency of CD34(+) cells that give rise to endothelial colonies, CD34(+) cells derived from FL were incubated with VEGF and fibroblast growth factor (FGF)-2. Subsequent isolation and plating of nonadherent FL-derived VEGFR-2(+) cells with VEGF and FGF-2 resulted in differentiation of AC133(+ )VEGFR-2(+) cells into adherent AC133(-)VEGFR-2(+)Ac-LDL(+ )(acetylated low-density lipoprotein) colonies (plating efficiency of 3%). In an in vivo human model, we have found that the neo-intima formed on the surface of left ventricular assist devices is colonized with AC133(+)VEGFR-2(+) cells. These data suggest that circulating CD34(+) cells expressing VEGFR-2 and AC133 constitute a phenotypically and functionally distinct population of circulating endothelial cells that may play a role in neo-angiogenesis.
The absorption of dietary non-heme iron by intestinal enterocytes is crucial to the maintenance of body iron homeostasis. This process must be tightly regulated since there are no distinct mechanisms for the excretion of excess iron from the body. An insight into the cellular mechanisms has recently been provided by expression cloning of a divalent cation transporter (DCT1) from rat duodenum and positional cloning of its human homologue, Nramp2. Here we demonstrate that Nramp2 is expressed in the apical membrane of the human intestinal epithelial cell line, Caco 2 TC7, and is associated with functional iron transport in these cells with a substrate preference for iron over other divalent cations. Iron transport occurs by a proton-dependent mechanism, exhibiting a concurrent intracellular acidification. Taken together, these data suggest that the expression of the Nramp2 transporter in human enterocytes may play an important role in intestinal iron absorption.
Lingual nerve injury is an uncommon complication of laryngoscopy. We report a case of isolated unilateral lingual nerve injury that occurred during suspension microlaryngoscopy. The injury was transient, with complete return of sensation within 3 months after surgery. Several mechanisms have been proposed to explain the occurrence of lingual nerve injury during laryngoscopy, including direct compression of the nerve caused by the laryngoscope, stretching of the nerve caused by cricoid pressure or instrumentation, and compression of the nerve between the medial and lateral pterygoid caused by manipulation of the mandible. The precise mechanism of injury in this case was not obvious, but stretching of the lingual nerve caused by pressure of the suspended laryngoscope on the tongue or retrolingual region was likely. The transient nature of the injury and the rapid return of the nerve to baseline function in this case are consistent with a neurapraxic injury.
Previous studies from our laboratory demonstrated that the latency, tumor growth, and metastatic progression of polyoma middle T-induced mammary tumor in an FVB/NJ inbred mouse background could be significantly altered by the introduction of different genetic backgrounds. In this study we extend these findings by mapping a number of interacting quantitative trait loci responsible for the changes in phenotype. Introduction of the I/LnJ inbred genetic background into the FVB/NJ-PyMT animal significantly accelerated the appearance of the primary tumor (35 vs. 57 days postnatal, p < 10(-7)). A backcross mapping panel was established, and loci responsible for the tumor acceleration were detected on Chrs 15 and 9. Examination of the genotype/phenotype correlation revealed that the FVB/NJ but not the I/LnJ allele of the Chr 15 locus was associated with tumor acceleration and was conditional on the presence of I/LnJ allele on Chr 9. These loci, designated Apmt1 and Apmt2, map to homologous regions associated with LOH in human breast cancer. These results suggest that allelic variants of genes in these regions may contribute to age of onset in human breast cancer.
The transcription factor early growth response (Egr)-1 is an immediate-early gene product rapidly and transiently expressed after acute tissue injury. In contrast, in this report we demonstrate that lung tissue from patients undergoing lung reduction surgery for advanced emphysema, without clinical or anatomical evidence of acute infection, displays a selective and apparently sustained increase in Egr-1 transcripts and antigen, compared with a broad survey of other genes, including the transcription factor Sp1, whose levels were not significantly altered. Enhanced Egr-1 expression was especially evident in smooth muscle cells of bronchial and vascular walls, in alveolar macrophages, and some vascular endothelium. Gel shift analysis with (32)P-labeled Egr probe showed a band with nuclear extracts from emphysematous lung which was supershifted with antibody to Egr-1. Egr-1 has the capacity to regulate genes relevant to the pathophysiology of emphysema, namely those related to extracellular matrix formation and remodeling, thrombogenesis, and those encoding cytokines/chemokines and growth factors. Thus, we propose that further analysis of Egr-1, which appears to be up-regulated in a sustained fashion in patients with late stage emphysema, may provide insights into the pathogenesis of this destructive pulmonary disease, as well as a new facet in the biology of Egr-1.
This paper describes adolescent low back pain and tests its associations with environmental features of backpack load, time spent carrying loads, time sitting, and time playing sport, using data from 1269 adolescents in twelve volunteer high schools in Adelaide, South Australia. Backpacks were the preferred method of load carrying, two-thirds of wearers preferring to carry the load over two shoulders. The average load weighed 5.3 kg (approximating 10% of body weight). The youngest students carried approximately the same amount as the oldest students. Girls were more likely than boys to report recent low back pain, and there were gender- and age-specific associations between recent low back pain, the amount of time spent sitting, the backpack load and time spent carrying it, and time playing sport. Body mass was not a confounder of any association. These findings support ongoing concerns regarding environmental contributions to adolescent low back pain.
Stimulation of the lipoxygenase pathway in olive fruit initiates a cascade of reactions that begins with the regio- and stereospecific di-oxygenation of polyunsaturated fatty acids containing a cis, cis-1,4 pentadiene moiety. Later products of the pathway include volatiles that influence the organoleptic properties of harvested olive oil. In this study, we have investigated lipoxygenase activity in olive callus cultures, and found that there is evidence of several isoforms of the enzyme with different pH optima and substrate specificities. Endogenous lipoxygenase activity was detected throughout the growth cycle of olive callus, particularly during the log phase of growth, suggesting that olive lipoxygenases are intimately involved in growth. The most prominent lipoxygenase activity in tissue cultures was found to be soluble but significant activities were detected in the plastid fraction. In addition, hydroperoxide lyase (HPL) activity was measured in the calli; both 13- and 9-HPL activities were found which were particulate.
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BACKGROUND/AIMS: Hepatitis B mutant strains of virus emerging during treatment with the nucleoside analog lamivudine are being increasingly recognized. In the majority of lamivudine-resistant isolates the mutations have been reported to occur within the YMDD motif of the viral polymerase, either as a single mutation M552I or as M552V concomitant with L528M. We analyzed the time course and genetic succession pattern during the emergence of lamivudine resistance. METHODS: Seven patients with breakthrough viremia in the setting of chronic hepatitis (n=5) or recurrent HBV after liver transplantation (n=2) were investigated. Pre- and post-breakthrough serum samples were evaluated by single- or second-round PCR amplification and sequencing analysis. RESULTS: Genotypic succession of the virus populations was observed to occur from M552I to M552I/L528M (n=2) and from L528M to M552V/L528M (n=1). The double mutations M552I/L528M (n=4) or M552V/L528M (n=2) were found in six out of seven patients, and represented the stable virus populations throughout the follow-up period. Breakthrough viremia was not associated with the single L528M mutation. The mean duration of uninterrupted treatment with lamivudine until breakthrough was 422 days (range 182-642) and was longer in the setting of chronic hepatitis B than in recurrent hepatitis B after liver transplantation. HBV DNA levels after breakthrough were lower than pretreatment levels in the majority of patients with chronic hepatitis but higher after liver transplantation. CONCLUSION: Our observations show that the virus populations conferring resistance to lamivudine can evolve from single to double mutations at amino acid 552 and 528 of the HBV polymerase, and that M552I/ L528M or M552V/L528M seem to be the predominant mutations arising during long-term antiviral therapy with lamivudine.
The development and validation of a reversed-phase liquid chromatographic method for the determination of the related substances of 2-[N-[(S)-1-Ethoxycarbonyl-3-phenylpropyl]-L-alanyl]-(1S, 3S, 5S)-2-azabicyclo[3.3.0]octane-3-carboxylic acid (ramipril) in Altace capsules is described. The method utilizes an ion-pairing agent and a simple two-step gradient for the separation of ramipril and ten related substances from each other in a 40-min run time. Four of the related substances are ramipril diastereomers. To the best of our knowledge, no method described previously in the literature has demonstrated resolution of ramipril from this set of related substances. No method for the determination of the related substances of ramipril is currently described in the United States Pharmacopoeia or the European Pharmacopoeia. The proposed method was validated with respect to accuracy, precision, linearity, and specificity. Also, the method was determined to be robust with regards to the following parameters: mobile phase apparent pH: mobile phase organic content: mobile phase perchlorate concentration; detection wavelength and time dependence of sample and standard stability.
Recent postmortem studies have been suggesting that a defect of GABAergic neurotransmission might occur in the corticolimbic system of subjects with schizophrenia and bipolar disorder. To explore this possibility, a method for immunolocalizing the 65 kdalton isoform of glutamate decarboxylase (GAD(65)) has been developed and applied to the anterior cingulate (ACCx) and prefrontal (PFCx) cortices of 12 normal controls (CONs), 12 schizophrenics (SZs) and 5 manic depressive (MDs) subjects. A computer-assisted technique was employed under strictly blind conditions to determine the density of GAD(65)-IR terminals in apposition with pyramidal (PNs) and nonpyramidal (NPs) neurons and in neuropil (NPL) of layers II, III, V and VI of each cortical region. For SZs, no difference in the numerical density of GAD(65)-IR terminals in contact with either PNs or NPs or in NPL of layers II-VI in ACCx or PFCx was detected. There were also no differences in the size of either PNs and NPs that could have influenced the nature of these findings. Using a pixel count analysis, the size of IR terminals was, however, found to be increased in layers II (10.3%) and III (15.8%) of SZs, but only in subjects treated with neuroleptic drugs. For MDs, the density of GAD(65)-IR terminals was significantly reduced in all four layers of ACCx, but these differences were most significant in layers II (27.8%) and III (37.2%), whether or not the subjected were treated with neuroleptics. In PFCx, the MDs showed similar differences in terminal density for PNs and NPs but not neuropil in the four laminae examined. The MD group showed no differences in either the size of cell bodies or IR terminals. Age and PMI did not account for any of the differences between the CONs vs SZs and MDs. Overall, the results of this study, though preliminary, suggest that there may be complex changes in GABAergic terminals in SZ and MD, ones that may vary with respect to primary diagnosis and neuroleptic exposure.
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UNLABELLED: De novo HBV infection post-liver transplantation (LT) from an anti-HBc seropositive donor rarely presents as acute failure. We report a 42-year-old Caucasian female, HBsAg and anti-HBc seronegative, with primary biliary cirrhosis who received an allograft from a HBsAg negative, anti-HBc seropositive donor. The patient, previously vaccinated years pre-LT, was re-vaccinated against HBV and 1 year post-LT had an anti-HBs titre of 256 IU/l. Two years post-LT, elevated serum aminotransferases and worsening liver function with an INR of 2.0 developed. The HBsAg became positive, anti-HBs undetectable and serum HBV-DNA >2000 pg/ml by hybridisation assay. Liver biopsy revealed significant ballooning degeneration, piecemeal necrosis and positive immunostaining for HBsAg. Progressive liver failure developed followed by sepsis and terminal multi-organ failure. Subsequent analysis of the predominant HBV strain revealed mutations in the "a" determinant: Met 133 Thr (codon change ATG to ACG) and Asn 131 Thr. CONCLUSION: ' Acute de novo HBV infection from an anti-HBc sero-positive donor may occur long after LT despite protective anti-HBs titres post-vaccination secondary to the emergence of "a" determinant mutated strains of HBV.
STUDY DESIGN: Prospective, observational. OBJECTIVES: To investigate the prevalence of orthostatic hypotension (OH), its associated signs and symptoms, and the resulting limitation to treatment during initial physiotherapy treatments involving mobilisation for patients with an acute spinal cord injury (SCI). SETTING: Spinal Injuries Units, Royal Adelaide Hospital and Hampstead Rehabilitation Centre, Adelaide, South Australia. METHODS: Fourteen of 17 consecutive patients admitted with an acute SCI completed the study. Non-invasive measurement of systolic and diastolic blood pressure (BP), heart rate and percutaneous oxygen saturation were recorded during a 10-min baseline period with the patient resting in supine, and then at 1-min intervals for the first 10 min of physiotherapy treatments that involved mobilisation (ie sitting or standing). Following cessation of the treatment and return to the supine position, further measurements were made immediately and following 5 min of rest. Visual signs and patient reported symptoms of OH and any perceived limitation to therapy were also recorded. The study period comprised the first 10 physiotherapy treatments that involved mobilisation. RESULTS: BP changes indicative of OH occurred during 73.6% of mobilisation treatments. Of these treatments, accompanying signs and symptoms of OH were noted on 58.9% of occasions and were perceived as limiting treatment on 43.2% of occasions. Patients with tetraplegia had a higher prevalence of OH and a greater fall in BP than patients with paraplegia, irrespective of whether their lesion was complete or incomplete. CONCLUSION: Blood pressure changes indicative of OH and accompanying signs and symptoms of OH are a common occurrence during the physiotherapy mobilisation of patients with an acute SCI.
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Advanced practice nurses (APNs) in the USA are registered nurses who hold masters or doctoral degrees in a specialized area of nursing. They provide advanced clinical care to clients, manage health care systems and influence health care decision-making through expert clinical reasoning and research and theory-based action. APN impact on health care outcomes is supported by studies using physician-focused indicators, although a few studies have identified several that are sensitive to or reflective of advanced practice nursing. A modified Delphi survey was conducted during May 1997-December 1998 to determine the outcome indicators APNs recommend for use in measuring their effect on care delivery outcomes. A convenience sample of 66 APNs attending a statewide outcomes conference identified 27 potential outcome indicators. These indicators were included in a mailed survey sent to APNs working in Tennessee. Respondents were asked to rate each indicator for validity, sensitivity, feasibility, utility and cost. In the second round of the survey, they were asked whether or not they agreed with the rank ordering of indicators, which was determined by the means calculated from responses in the first round. The 10 highest ranked indicators were satisfaction with care delivery, symptom resolution/reduction, perception of being well cared for, compliance/adherence with treatment plan, knowledge of patients and families, trust of care provider, collaboration among care providers, frequency and type of procedures ordered and quality of life. APNs identified both direct and indirect measures of effect on care delivery outcomes. Some of these are currently used as indicators of advanced practice, but many are not. Additional research is needed to determine whether the indicators proposed are valid and sensitive to advanced practice care by nurses.