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Biomedical subjects

R D Goldman

Publications and source records attributed to R D Goldman.

At least 19 recordsLinked to original sources
PubMed2006

Paediatric emergency department staff perceptions of infection control measures against severe acute respiratory syndrome.

OBJECTIVES: To determine paediatric emergency department (ED) staff perceptions of the effectiveness and practice of infection control measures against a novel virulent pathogen. METHODS: All medical staff of the paediatric ED in a tertiary medical centre completed a written questionnaire near the onset of the severe acute respiratory syndrome (SARS) outbreak. Level of concern regarding SARS, and perceptions of effectiveness and use of infection control measures were assessed on a 5 point scale. Statistical analysis was performed using chi2 test and one way analysis of variance with significance at p<0.05. RESULTS: Response rate was 97% (116/120). All scores were given out of 5 possible points. Using isolation rooms (mean score 4.6), wearing a mask when examining patients (4.5), and handwashing (4.5) were considered most effective. Staff physicians reported handwashing more than nurses and trainees (4.9 v 4.5 and 4.5, respectively; p<0.05) while other measures were reported equally. Respondents considering SARS a high public health threat reported higher compliance with handwashing (4.8 v 4.4), always wearing a mask (3.9 vs 3.2) and gloves (3.6 v 2.9) in the ED (p<0.05), but not eye protection (3.4 v 3.0), gown use (4.9 v 4.7), or wearing a mask when examining patients (5.0 v 4.8). Staff who considered combined infection control measures effective in protecting patients and healthcare workers did not report increased compliance. CONCLUSIONS: Eye protection was perceived as only moderately effective in protecting against the spread of SARS, and reported compliance was relatively poor among ED staff. Concern of SARS as a public health threat rather than perceived effectiveness of infection control measures appears to have a greater impact on compliance.

Adult↗
PubMed2006

Internet health information use and e-mail access by parents attending a paediatric emergency department.

OBJECTIVES: To document internet access and health related usage patterns by families of children in a large paediatric emergency department (ED), and to discover if parents want the internet to become a tool for transferring medical test results. METHODS: This was a pre-tested, 21 item, interview conducted with parents at the paediatric ED in Toronto over 3 months. Descriptive statistics and frequency distributions were calculated and variables associated with parents wishing to access results electronically were examined. RESULTS: In total, 950 parents completed the interview (93%), of whom 87% reported routine internet access, 75% reported having an e-mail account, and 60% accessed their e-mail once or more a day. Over half (56%) reported searching the internet for health related information, with 8.5% of these searching immediately preceding their visit. Nearly three quarters (73%) indicated they would like to receive an e-mail containing the results of tests conducted in the ED; 66% of all respondents and 89% of those with e-mail indicated that they would like their child's primary care provider to receive information electronically. CONCLUSION: The majority of families have internet access and most want to receive medical information electronically and to send it to the primary provider. The vast use of internet for health related information emphasises the need to guide parents regarding reliable resources online, possibly as part of their ED visit.

Adolescent↗
PubMed2002

Is the sampling site along the umbilical artery significant?

The purpose of umbilical blood sampling is to obtain accurate reflection of fetal acid-base status at birth. The site along the umbilical artery from which blood should be sampled postpartum was not specified. We evaluated if blood gases and pH values from three sampling sites along the umbilical artery are different. After defining the range of intraobserver (method) variability, blood pO(2), pCO(2), and pH were directly determined. The data showed consistent and significant increases in arterial pH and pCO(2) values and decreases in pO(2) values from near the fetal cord insertion to the placenta. The largest difference was noted between the fetal site and the placental plate and the smallest between the site near the placental cord insertion and the placental plate. We conclude that the site of cord blood sampling should be standardized and the umbilical artery should be sampled at a site nearest to the neonate.

Blood Gas Analysis↗
PubMed2001

Dynamic disruptions in nuclear envelope architecture and integrity induced by HIV-1 Vpr.

Human immunodeficiency virus-1 (HIV-1) Vpr expression halts the proliferation of human cells at or near the G2 cell-cycle checkpoint. The transition from G2 to mitosis is normally controlled by changes in the state of phosphorylation and subcellular compartmentalization of key cell-cycle regulatory proteins. In studies of the intracellular trafficking of these regulators, we unexpectedly found that wild-type Vpr, but not Vpr mutants impaired for G2 arrest, induced transient, localized herniations in the nuclear envelope (NE). These herniations were associated with defects in the nuclear lamina. Intermittently, these herniations ruptured, resulting in the mixing of nuclear and cytoplasmic components. These Vpr-induced NE changes probably contribute to the observed cell-cycle arrest.

Active Transport, Cell Nucleus↗
PubMed2001

A role for nuclear lamins in nuclear envelope assembly.

The molecular interactions responsible for nuclear envelope assembly after mitosis are not well understood. In this study, we demonstrate that a peptide consisting of the COOH-terminal domain of Xenopus lamin B3 (LB3T) prevents nuclear envelope assembly in Xenopus interphase extracts. Specifically, LB3T inhibits chromatin decondensation and blocks the formation of both the nuclear lamina-pore complex and nuclear membranes. Under these conditions, some vesicles bind to the peripheral regions of the chromatin. These "nonfusogenic" vesicles lack lamin B3 (LB3) and do not bind LB3T; however, "fusogenic" vesicles containing LB3 can bind LB3T, which blocks their association with chromatin and, subsequently, nuclear membrane assembly. LB3T also binds to chromatin in the absence of interphase extract, but only in the presence of purified LB3. Additionally, we show that LB3T inhibits normal lamin polymerization in vitro. These findings suggest that lamin polymerization is required for both chromatin decondensation and the binding of nuclear membrane precursors during the early stages of normal nuclear envelope assembly.

Animals↗
PubMed2001

Insights into the dynamic properties of keratin intermediate filaments in living epithelial cells.

The properties of keratin intermediate filaments (IFs) have been studied after transfection with green fluorescent protein (GFP)-tagged K18 and/or K8 (type I/II IF proteins). GFP-K8 and -K18 become incorporated into tonofibrils, which are comprised of bundles of keratin IFs. These tonofibrils exhibit a remarkably wide range of motile and dynamic activities. Fluorescence recovery after photobleaching (FRAP) analyses show that they recover their fluorescence slowly with a recovery t(1/2) of approximately 100 min. The movements of bleach zones during recovery show that closely spaced tonofibrils (<1 microm apart) often move at different rates and in different directions. Individual tonofibrils frequently change their shapes, and in some cases these changes appear as propagated waveforms along their long axes. In addition, short fibrils, termed keratin squiggles, are seen at the cell periphery where they move mainly towards the cell center. The motile properties of keratin IFs are also compared with those of type III IFs (vimentin) in PtK2 cells. Intriguingly, the dynamic properties of keratin tonofibrils and squiggles are dramatically different from those of vimentin fibrils and squiggles within the same cytoplasmic regions. This suggests that there are different factors regulating the dynamic properties of different types of IFs within the same cytoplasmic regions.

Animals↗
PubMed2001

Mitotic reorganization of the intermediate filament protein nestin involves phosphorylation by cdc2 kinase.

The intermediate filament protein nestin is expressed during early stages of development in the central nervous system and in muscle tissues. Nestin expression is associated with morphologically dynamic cells, such as dividing and migrating cells. However, little is known about regulation of nestin during these cellular processes. We have characterized the phosphorylation-based regulation of nestin during different stages of the cell cycle in a neuronal progenitor cell line, ST15A. Confocal microscopy of nestin organization and (32)P in vivo labeling studies show that the mitotic reorganization of nestin is accompanied by elevated phosphorylation of nestin. The phosphorylation-induced alterations in nestin organization during mitosis in ST15A cells are associated with partial disassembly of nestin filaments. Comparative in vitro and in vivo phosphorylation studies identified cdc2 as the primary mitotic kinase and Thr(316) as a cdc2-specific phosphorylation site on nestin. We generated a phosphospecific nestin antibody recognizing the phosphorylated form of this site. By using this antibody we observed that nestin shows constitutive phosphorylation at Thr(316), which is increased during mitosis. This study shows that nestin is reorganized during mitosis and that cdc2-mediated phosphorylation is an important regulator of nestin organization and dynamics during mitosis.

Amino Acid Sequence↗
PubMed2001

Spatiotemporal analysis of flow-induced intermediate filament displacement in living endothelial cells.

The distribution of hemodynamic shear stress throughout the arterial tree is transduced by the endothelium into local cellular responses that regulate vasoactivity, vessel wall remodeling, and atherogenesis. Although the exact mechanisms of mechanotransduction remain unknown, the endothelial cytoskeleton has been implicated in transmitting extracellular force to cytoplasmic sites of signal generation via connections to the lumenal, intercellular, and basal surfaces. Direct observation of intermediate filament (IF) displacement in cells expressing green fluorescent protein-vimentin has suggested that cytoskeletal mechanics are rapidly altered by the onset of fluid shear stress. Here, restored images from time-lapse optical sectioning fluorescence microscopy were analyzed as a four-dimensional intensity distribution function that represented IF positions. A displacement index, related to the product moment correlation coefficient as a function of time and subcellular spatial location, demonstrated patterns of IF displacement within endothelial cells in a confluent monolayer. Flow onset induced a significant increase in IF displacement above the nucleus compared with that measured near the coverslip surface, and displacement downstream from the nucleus was larger than in upstream areas. Furthermore, coordinated displacement of IF near the edges of adjacent cells suggested the existence of mechanical continuity between cells. Thus, quantitative analysis of the spatiotemporal patterns of flow-induced IF displacement suggests redistribution of intracellular force in response to alterations in hemodynamic shear stress acting at the lumenal surface.

Animals↗
PubMed2001

New horizons in cytoskeletal dynamics: transport of intermediate filaments along microtubule tracks.

Until recently, the dynamic properties of intermediate filaments (IF) were attributed primarily to the exchange of subunits between a disassembled pool and polymerized 10nm filaments. During interphase, this subunit exchange process was thought to produce local modifications in IF structure. During cell division, shifts in the equilibrium between subunits and polymers were thought to lead to either the global or regional disassembly of IF networks, thereby facilitating their distribution into daughter cells. Recently, novel structural forms of IF that undergo rapid and directed transport in several cell types were revealed. Time-lapse observations of motile IF structures in different cell systems have also revealed novel insights into the mechanisms underlying the transport of cytoskeletal components throughout the cytoplasm and the molecular basis of the 'crosstalk' between different cytoskeletal systems.

Animals↗
PubMed2001

Structure and function of a vimentin-associated matrix adhesion in endothelial cells.

The alpha4 laminin subunit is a component of endothelial cell basement membranes. An antibody (2A3) against the alpha4 laminin G domain stains focal contact-like structures in transformed and primary microvascular endothelial cells (TrHBMECs and HMVECs, respectively), provided the latter cells are activated with growth factors. The 2A3 antibody staining colocalizes with that generated by alphav and beta3 integrin antibodies and, consistent with this localization, TrHBMECs and HMVECs adhere to the alpha4 laminin subunit G domain in an alphavbeta3-integrin-dependent manner. The alphavbeta3 integrin/2A3 antibody positively stained focal contacts are recognized by vinculin antibodies as well as by antibodies against plectin. Unusually, vimentin intermediate filaments, in addition to microfilament bundles, interact with many of the alphavbeta3 integrin-positive focal contacts. We have investigated the function of alpha4-laminin and alphavbeta3-integrin, which are at the core of these focal contacts, in cultured endothelial cells. Antibodies against these proteins inhibit branching morphogenesis of TrHBMECs and HMVECs in vitro, as well as their ability to repopulate in vitro wounds. Thus, we have characterized an endothelial cell matrix adhesion, which shows complex cytoskeletal interactions and whose assembly is regulated by growth factors. Our data indicate that this adhesion structure may play a role in angiogenesis.

Antibodies, Monoclonal↗
PubMed2001

Maternal age and birth weight characteristics of twins born to nulliparous mothers: a population study.

In order to examine birth weight characteristics of twins delivered to nulliparous mothers in relation to maternal age, we used a population-based cohort of Israeli twins delivered between 1993-98 to select all 4793 (37.6%) nulliparas who delivered twins. Maternal age was subdivided as less than 20 years, 20-24, 25-29, 30-34, 35-39, and 40 years or more. We counted the frequencies of each total twin birth weight (twin A + twin B) in each of three categories (less than 3000, 3000-4999, and more than 5000 g) and the frequency of very low birth weight (VLBW, less than 1500 g) neonates in each of the six maternal age categories. There were significantly more nulliparas in the twin population at age groups less 30 years and significantly less at ages 30 years or more. We found a highly significant inverse correlation between the proportion of nulliparas and maternal age group, decreasing from 71.8% at less than 20 years to 18.6% at age 35-39 years (% nulliparas = 85 - 13.7 x age group, Pearson R2 = 0.98). However, this trend changed abruptly to the observed figure of 25.9% nulliparas aged 40 years or more instead of the expected 2.8%. We failed to reveal any significant difference in birth weight characteristics between the maternal age groups (all p > 0.05, all confidence intervals included 1.0). The more than tenfold deviation of the observed from the predicted frequency of nulliparas aged 40 years or more suggests that a different relationship between parity and age occurs at this age group. Maternal age of nulliparas is not associated with different birth weight characteristics of their twins.

Age Factors↗
PubMed2001

Incidence and birth weight characteristics of twins born to mothers aged 40 years or more compared with 35-39 years old mothers: a population study.

OBJECTIVE: To compare the incidence of twin births and their birth weight characteristics in mothers aged > or = 40 years with those of mothers aged 35-39 years. METHODS: We used a population-based cohort of Israeli twins delivered between 1993-98 to compare birth weight characteristics of 510 and 2102 twin pairs delivered to mothers aged > or = 40 years (cases) and 35-39 years (controls), respectively. RESULTS: The incidence of twin mothers aged 40 years or more increased 50% during the study period, ten times more than mothers aged 35-39. There were significantly more nulliparas (P < .001, OR 1.54, 95% CI 1.2, 1.9) and more para > or = 4 (P < .004, OR 1.38, 95% CI 1.1, 1.7) among older mothers. Irrespective of parity, there were no significant differences between mean twin birth weight, total twin birth weight < 3000 g, 3000-4999 g, and > or = 5000 g, and frequencies of very low birth weight neonates. CONCLUSIONS: Twin birth at the age of > or = 40 years is significantly more likely among either nulliparas or para > or = 4. Birth weight characteristics of twins delivered to mothers aged > or = 40 years are not different from those delivered to 35-39 years old mothers.

Adult↗
PubMed2000

Nuclear lamins A and B1: different pathways of assembly during nuclear envelope formation in living cells.

At the end of mitosis, the nuclear lamins assemble to form the nuclear lamina during nuclear envelope formation in daughter cells. We have fused A- and B-type nuclear lamins to the green fluorescent protein to study this process in living cells. The results reveal that the A- and B-type lamins exhibit different pathways of assembly. In the early stages of mitosis, both lamins are distributed throughout the cytoplasm in a diffusible (nonpolymerized) state, as demonstrated by fluorescence recovery after photobleaching (FRAP). During the anaphase-telophase transition, lamin B1 begins to become concentrated at the surface of the chromosomes. As the chromosomes reach the spindle poles, virtually all of the detectable lamin B1 has accumulated at their surfaces. Subsequently, this lamin rapidly encloses the entire perimeter of the region containing decondensing chromosomes in each daughter cell. By this time, lamin B1 has assembled into a relatively stable polymer, as indicated by FRAP analyses and insolubility in detergent/high ionic strength solutions. In contrast, the association of lamin A with the nucleus begins only after the major components of the nuclear envelope including pore complexes are assembled in daughter cells. Initially, lamin A is found in an unpolymerized state throughout the nucleoplasm of daughter cell nuclei in early G1 and only gradually becomes incorporated into the peripheral lamina during the first few hours of this stage of the cell cycle. In later stages of G1, FRAP analyses suggest that both green fluorescent protein lamins A and B1 form higher order polymers throughout interphase nuclei.

Anaphase↗