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Biomedical subjects

A Anderson

Publications and source records attributed to A Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1999

Out-of-hospital violence injury surveillance: quality of data collection.

STUDY OBJECTIVE: The recognized need to improve data collection for violence prevention may be met, in part, by using out-of-hospital data for injury surveillance. The purpose of the Prehospital Violence Injury Surveillance project was to examine the extent to which paramedics can adequately collect information about injuries, particularly intentional injuries, at emergency scenes. METHODS: Paramedics in a large Midwestern metropolitan area were trained to assess violence-related events and collect relevant data using a modified ambulance run report form. Data collected from 8 violence-related training scenarios and from 13 ride-along observations were analyzed to estimate paramedic interrater reliability using the kappa statistic. Data from 7,363 run report forms, filed during a 3-month study period, were abstracted and analyzed for completeness and quality. RESULTS: Paramedics demonstrated fair to good, and sometimes excellent, interrater agreement when documenting the training scenarios. Paramedics revealed barriers to collecting violence-related out-of-hospital data. The paramedics and the observer disagreed in documenting 77% of the ride-along observations. Overall, 73% of abstracted run report forms showed documentation errors, with more than 99% of these reports containing errors of omission and 29% showing internal documentation inconsistencies. Despite the emphasis on violence-related data, documentation of domestic abuse screening was missing from more than 99% of run reports from female patients. CONCLUSION: Significant barriers to quality out-of-hospital data collection were identified during study implementation and in abstracted run reports. These barriers included the following: lack of organizational support; characteristics of the violence-related data elements; design of the ambulance run report form; and paramedic knowledge, attitudes, and behaviors regarding data collection.

Adult↗
PubMed1999

The results of routine primary closure in carotid endarterectomy.

PURPOSE OF STUDY: The aims of this study were to determine the incidence of restenosis following carotid endarterectomy with primary closure of the arteriotomy and to observe the natural history of disease progression in the 1st postoperative year. METHODS: The study group consisted of a consecutive series of 126 patients undergoing carotid endarterectomy. Duplex imaging was performed preoperatively and at 8 weeks, 6 months and 1 year postoperatively. RESULTS: Five patients (4%) had a residual stenosis. At 12 months, the overall restenosis rate was 15%: 8.5% for males and 28.9% for females. None of these restenoses were symptomatic. There was no significant difference in the diameter of the internal carotid artery between male and female patients (U = 896, P = 0.60) and no significant difference in the diameter of the arteries that had restenosed at 12 months and those that had remained patent (U = 391, P = 0.33). CONCLUSIONS: Carotid endarterectomy with primary closure is associated with a low incidence of restenosis in men, but not in women. Criteria for selective patching should consider both gender and vessel calibre.

Aged↗
PubMed1999

Raman and infrared studies of nucleosides at high pressures: I. Adenosine.

Room temperature Raman and infrared (IR) spectra of crystalline adenosine at pressures between 1 atm and 10 GPa are reported. Vibrational modes were identified through assignments in the literature. Many modes were found to increase in frequency with pressure; however, some irregularities were observed. Discontinuities were observed in numerous Raman and IR modes near 2.5 GPa, indicating a phase transition. The modes associated with the glycosidic bond shift significantly down in frequency near this pressure, suggesting a weakening of the associated bond. The IR modes associated with hydrogen-stretching motions were found to decrease in frequency with pressure.

Adenosine↗
PubMed1999

Acute ureteral elongation in two animal models using a balloon expander.

BACKGROUND AND OBJECTIVE: Repair of ureteral injuries and strictures often necessitates a major reconstructive procedure such as a psoas hitch, Boari flap, renal mobilization, ileal interposition, or autotransplantation. Tissue expanders have been used to elongate nerves and arteries. We examined the effects of acute ureteral elongation in two animal models. MATERIALS AND METHODS: In eight female rabbits, we exposed the left ureter through a midline incision and placed a Ruiz-Cohen balloon beneath the undermined portion. The expander was then inflated until the ureter was tightly stretched across it. After deflation, the expanded segment was measured in situ and compared with its original length. Follow-up urography was performed, and the tissue was harvested and examined by a pathologist. The same procedure was performed in five pigs; however, in these animals, a segment of ureter was excised, and a ureteroureterostomy was performed, after the acute expansion. RESULTS: We were able to achieve acute elongation of the expanded ureteral segment. The mean elongation was 31.3% in the rabbits and 32.0% in the pigs. An intravenous urogram (IVU) 6 weeks after the elongation showed a functioning kidney and a patent ureter. Histologic examination of the ureter within 24 hours after the expansion revealed that all segments were viable, the luminal epithelium was intact, and the muscular layers appeared normal. At 6 weeks, the expanded segment showed mild inflammatory changes, but the overall morphology, size, and cytology findings were similar to those of a normal control. CONCLUSIONS: Acute ureteral elongation using a tissue expander is a new method of increasing ureteral length. It may be useful to cover defects that would need major operations with greater morbidity.

Anastomosis, Surgical↗
PubMed1999

Ovulation induction with low dose alternate day recombinant follicle stimulating hormone (Puregon).

We investigated whether a recombinant follicle stimulating hormone (FSH) (Puregon) can be administered less frequently and at lower doses during ovulation induction than is current practice. Patients (20-35 years, body mass index <30 kg/m(2)) with infertility and chronic anovulation secondary to polycystic ovarian syndrome and resistant to previous clomiphene treatment received (Puregon); 100 IU, n = 17 patients, or 50 IU, n = 10 patients) on alternate days. After 2 weeks and in the absence of follicular recruitment, doses were increased stepwise at weekly intervals (50 IU/alternate days). Twenty-two cycles out of 27 were ovulatory. There were six pregnancies, five from Puregon (100 IU) and one from Puregon (50 IU); four pregnancies proceeded to term. The duration of stimulation (mean, range) with Puregon (100 IU) was 16.4, 7-29 and Puregon (50 IU) 19.1, 8-38 days. The gonadotrophin doses administered (mean; range) were 689, 200-1800 IU (Puregon 50 IU) and 939, 400-2300 IU (Puregon 100 IU). We conclude that low dose alternate day Puregon treatment is suitable for this difficult patient group.

Adult↗
PubMed1999

Modeling analysis of change in neurologic abnormalities in children born prematurely: a novel approach.

The purpose of this longitudinal study was to evaluate changes in neurologic abnormalities in 212 preterm and 128 full-term children. Preterm infants with severe medical complications were considered at high risk, while those with milder complications were considered at low risk for neurodevelopmental abnormality. The patterns of change in neurologic status for the high- and low-risk preterm and term groups across 6, 12, 24, 40, and 54 months of age were compared using growth modeling analysis. As expected, the term group showed minimal change, while the two preterm groups demonstrated complex, nonlinear patterns of change in neurologic abnormalities. While the results demonstrate improvement over time in both groups of preterm infants, 35% of the children in the high-risk group had neurologic scores in the borderline or abnormal range at 54 months. These findings demonstrate that neurologic deficits are still evident at preschool age in some preterm children and that these deficits are related to the severity of neonatal complications.

Brain Damage, Chronic↗
PubMed1999

Effect of calcium channel antagonists nifedipine and nicardipine on rat cytochrome P-450 2B and 3A forms.

Calcium channel antagonists are widely prescribed for treatment of hypertension. In this study, we examined whether treatment with the calcium channel antagonists, nicardipine, nifedipine or diltiazem, alters cytochrome P-450 2B or 3A (CYP2B or CYP3A, respectively) expression in rat liver. Western blot analyses were undertaken using antibodies specific for one or several members of these cytochrome P-450 subfamilies. Nicardipine was found to be an effective inducer of CYP3A; in particular, CYP3A23 was increased approximately 36-fold following treatment with 100 mg of nicardipine/kg/day. Nicardipine induced CYP2B forms up to approximately 3.1-fold. Nifedipine did not alter CYP3A expression but did increase CYP2B expression such that total CYP2B, CYP2B1, and CYP2B2v (a splice variant of CYP2B2) were increased approximately 5- to 15-fold after treatment with 100 mg of nifedipine/kg/day, with increases in benzyloxyresorufin O-dealkylase and erythromycin N-demethylase activities, respectively. The distinct differences in cytochrome P-450 induction profile induced by nicardipine and nifedipine suggest that they may enhance cytochrome P-450 expression by different mechanisms unrelated to their effects on calcium channels.

Animals↗
PubMed1999

Work-related assault injuries among nurses.

Work-related violence is a major public health problem; however, there is a serious deficiency in the knowledge of risk factors for this problem. The purpose of this case-control study was to identify risk factors for work-related assault injuries among nurses. We used unconditional logistic regression to model the dependence of work-related assault injuries on each exposure of interest and the respective confounders. We found a decreased rate for the presence of security personnel (RR = 0.40; 95% CI = 0.19-0.82). We found increased rates for the following factors: the perception that administrators considered assault to be part of the job (RR = 8.14; 95% CI = 3.76-17.60); having received assault prevention training in the current workplace (RR = 4.64; 95% CI = 2.33-9.23); a high (>5) vs. low (<2) patient/personnel ratio (RR = 2.54; 95% CI = 1.13-5.70); working predominantly with patients with mental illness (RR = 3.5; 95% CI = 1.41-8.85); and working with patients who had more than 1- to 4-week and more than 4-week lengths of stay in the institution vs. <1 day (RR = 8.85; 95% CI = 1.58-49.52 and 4.25; 95% CI = 1.17-15.39, respectively).

Adult↗
PubMed1998

Structural principles that govern the peptide-binding motifs of class I MHC molecules.

The peptides that bind class I MHC molecules are restricted in length and often contain key amino acids, anchor residues, at particular positions. The side-chains of peptide anchor residues interact with the polymorphic complementary pockets in MHC peptide-binding grooves and provide the molecular basis for allele-specific recognition of antigenic peptides. We establish correlations between class I MHC specificities for anchor residues and class I MHC sequence markers that occur at the polymorphic positions lining the structural pockets. By analyzing the pocket structures of nine crystallized class I MHC molecules and the modeled structures of another 39 class I MHC molecules, we show that class I pockets can be classified into families that are distinguishable by their common physico-chemical properties and peptide side-chain selectivities. The identification of recurrent structural principles among class I pockets makes it possible to greatly expand the repertoire of known peptide-binding motifs of class I MHC molecules. The evolutionary strategies underlying the emergence of pocket families is briefly discussed.

Alleles↗
PubMed1998

Endometrial carcinoma under the age of 40: reappraisal for oophorectomy in stage I disease.

Objective: To reappraise the rationale of castration and the necessity of retroperitoneal lymph node biopsy in patients with endometrial carcinoma under the age of 40 years.Methods: A retrospective review of 30 patients under the age of 40 among 815 patients who had primary endometrial cancer treatment was carried out. The review consisted of clinical data, surgical pathology, and survival rates, as well as a comparative study of the literature.Results: The average age was 35.1 years. Three-quarters of the patients (76.6%) had stage I disease. Almost half of them had risk factors for endometrial carcinoma. The pathologic type was adenocarcinoma in 83% and grade 1 in 57%. Among 23 patients with stage I disease, 7 (30.4%) had no residual disease. Even with 16 patients found to have residual disease, 10 had it confined to the endometrium. Ovarian malignancy was only seen in 2 instances. Five demonstrated corpus luteum. Only 3 (13%) had lymph node metastasis and all in advanced disease. Six (20%) of these patients had delayed treatment more than 6 months. The follow-up was 5 months to 19 years. All are living and free of disease in stage I and stage II. Both patients with stage III disease died.Conclusions: In view of low risks in these young women with stage I disease, a thorough surgical staging including lymph node resection is desirable and hysterectomy with ovarian preservation is the treatment of choice. Oophorectomy might be considered in patients with cancer of the ovaries or in advanced stages of disease.

Journal Article↗
PubMed1998

The CYP2B2 phenobarbital response unit contains an accessory factor element and a putative glucocorticoid response element essential for conferring maximal phenobarbital responsiveness.

Hepatic cytochrome P450s play a critical role in the metabolism of hydrophobic xenobiotics. One of the major unsolved problems in xenobiotic metabolism is the molecular mechanism whereby phenobarbital induces hepatic enzymes, particularly CYP2B1 and CYP2B2 in rat liver. By using primary rat hepatocytes for transfection analyses, we previously identified in the CYP2B2 5'-flank a 163-base pair Sau3AI fragment that confers phenobarbital inducibility on a cat reporter gene and that has the properties of a transcriptional enhancer. Transfection experiments with sub-regions of the Sau3AI fragment now indicate that a central core together with an upstream or downstream accessory element within the fragment can confer phenobarbital responsiveness. One such accessory element, AF1, was identified and localized. DNase I footprinting analysis revealed the presence of a footprint overlapping this AF1 element. It also identified three other major protected regions, two of which are putative recognition sites for known transcription factors. Site-directed mutagenesis indicated that a putative glucocorticoid response element as well as a nuclear factor 1 site and an associated nuclear receptor hexamer half-site are essential for conferring maximal phenobarbital inducibility. Taken together, the results indicate that phenobarbital induction of CYP2B2 requires interactions among multiple regulatory proteins and cis-acting elements constituting a phenobarbital response unit.

Animals↗
PubMed1998

The importance of water quality for media preparation.

The variability in pregnancy rates achieved among in-vitro fertilization (IVF) clinics may be partially attributable to the disparate quality of the water used in the preparation of culture media. The removal of contaminants in the water is of paramount importance since water constitutes the predominant component in any media formulation. To assist in the selection, operation and maintenance of a water purification system, the level of contaminants must be carefully monitored. Conductivity and resistance are used to measure the purity of natural and ultrapure water respectively. Feed water is analysed by an assortment of direct chemical means to determine the necessary system filtration steps. In general, high quality water can be produced by combined reverse osmosis and electrodeionization of treated tap water. Processed water is supplied to an ultrapure water system to provide final polished water. A detailed water processing protocol is presented along with quality assurance guidelines to ensure the consistent production of high quality ultrapure water suitable for in-vitro human embryo culture.

Animals↗
PubMed1998

Selective expression of estrogen receptor alpha and beta isoforms in human pituitary tumors.

The physiological effects of estrogen on the pituitary, including cellular proliferation and regulation of hormone synthesis, are mediated by the nuclear estrogen receptor (ER). The ER acts as a dimer to modulate gene transcription and contains specific functional domains encoded in different exons. Two separate, but related, forms of the receptor (ERalpha and ERbeta) exist, with distinct tissue and cell patterns of expression. Additional ER isoforms, generated by alternative messenger ribonucleic acid (mRNA) exon splicing, have been defined in several tissues and are postulated to play a role in tumorigenesis or in modulating the estrogen response. We examined 71 human pituitary adenomas of varying phenotypes and 6 normal pituitary specimens for ER mRNA forms by RT-PCR and hybridization blotting analysis. All prolactinomas (n = 14) contained ERalpha, and several contained ERbeta (5 of 14) mRNA. In comparison, 6 tumors that expressed PRL and GH expressed ERbeta (4 of 6) more frequently than ERalpha (3 of 6). ERbeta mRNA was also found more frequently in null cell (8 of 24 ERalpha and 14 of 24 ERbeta) and gonadotrope (13 of 21 ERalpha and 18 of 21 ERbeta) tumors. Additionally, ERbeta was found in 4 of 6 tumors that contained only GH, although ERalpha was not observed in this tumor type. Expression of the two ER forms within a tumor type was overlapping, but some tumors contained only 1 isoform. Expression of ERalpha mRNA splice variants also varied with cell type. All normal pituitaries contained ERalpha deletions of exon 4, 5, and 7, whereas only 2 of 6 samples contained the exon 2 deletion variant. Although the same ERalpha mRNA variants were observed among the various tumor types, the proportion of specific splice variants expressed varied. For example, most ER-positive prolactinomas expressed ERalpha variants with deletions of exon 2, 4, or 5, whereas gonadotropin tumors preferentially expressed the ERalpha exon 7 deletion variant. A novel ERbeta mRNA splice variant, missing exon 2, was observed in a majority of all ERbeta-positive tumors. Immunoblotting analysis of ERalpha and ERbeta proteins supported the mRNA results. Because ERalpha and ERbeta have different biological responses to selective ER modulators, and the ER deletion variants have biological effects distinct from those of the full-length ER, expression of these isoforms may influence the biological properties of these tumors and affect their ability to respond to estrogen and antiestrogen therapies.

Adenoma↗
PubMed1998

The preceptoring map for RN-to-BSN students.

RN-to-BSN students reflect an array of experiences often so diverse the traditional student placement challenges neither students nor preceptors. In response to this need for an alternate to the standard clinical placement for RN students, a collaborative model was developed. Because of dramatic changes in the health care environment, the "traditional" placement for students is no longer readily available nor necessarily appropriate. These circumstances, combined with the uniqueness of RN-to-BSN students prompted the authors to develop the Preceptoring Map. The model was developed in collaboration with the research department of Massachusetts General Hospital. The Preceptoring Map designates two tracks, the N track and the P track. Using Benner's novice to expert theories, the tracks were operationalized to the student population. Determining which track will be most appropriate is multifaceted. Included in the evaluation process are the students' work experiences and expertise, critical-thinking skills assessment, and self-assessment. Faculty review these outcomes, combined with an indepth interview with the placement coordinator, to match students and preceptors for the most successful clinical placements.

Clinical Competence↗
PubMed1997

Anesthetic activity of novel water-soluble 2 beta-morpholinyl steroids and their modulatory effects at GABAA receptors.

(3 alpha,5 alpha)-3-Hydroxypregnan-20-ones and (3 alpha,5 alpha)-3-hydroxypregnane-11,20-diones bearing a 2 beta-morpholinyl substituent were synthesized, and the utility of these steroids as anesthetic agents was evaluated through determination of their potency and duration of hypnotic activity in mice after intravenous administration. Alkylation of the morpholinyl substituent or chlorination at C-21 afforded the novel amino steroids (2 beta,3 alpha,5 alpha)-3-hydroxy-2-(2,2-dimethyl-4-morpholinyl)-pregnane-11,20-dione (19) and (2 beta,3 alpha,5 alpha)-21-chloro-3-hydroxy-2-(4-morpholinyl)pregnan-20-one (37) that were more potent and advantageously produced shorter sleep times than related compounds which were previously reported. Furthermore, salts of these and other amino steroids generally retained good aqueous solubility. In a radioligand binding assay the compounds inhibited the specific binding of [35S]-tert-butyl bicyclophosphorothionate to rat whole brain membranes, and in an electrophysiological assay they potentiated GABAA receptor-mediated currents recorded from voltage-clamped bovine chromaffin cells. These in vitro results are consistent with the anesthetic activity of the amino steroids being related to their modulatory effects at GABAA receptors.

Anesthesia↗
PubMed1997

Initial frequency of alleles for resistance to Bacillus thuringiensis toxins in field populations of Heliothis virescens.

The risk of rapid pest adaptation to an insecticide is highly dependent on the initial frequency of resistance alleles in field populations. Because we have lacked empirical estimates of these frequencies, population-genetic models of resistance evolution have relied on a wide range of theoretical estimates. The recent commercialization of genetically engineered cotton that constitutively produces an insecticidal protein derived from the biocontrol agent, Bacillus thuringiensis (Bt) has raised concern that we lack data needed to quantify the risk of insect pests such as Heliothis virescens rapidly adapting to this ecologically valuable class of toxins. By individually mating over 2,000 male H. virescens moths collected in four states to females of a Bt toxin-resistant laboratory strain, and screening F1 and F2 offspring for tolerance of the toxic protein, we were able to directly estimate the field frequency of alleles for resistance as 1.5 x 10(-3). This high initial frequency underscores the need for caution in deploying transgenic cotton to control insect pests. Our single-pair mating technique greatly increases the efficiency of detecting recessive resistance alleles. Because alleles that decrease target site sensitivity to Bt toxins and other insecticides are often recessive, this technique could be useful in estimating resistance allele frequencies in other insects exposed to transgenic insecticidal crops or conventional insecticides.

Journal Article↗
PubMed1997

Characterization of an insulin-like growth factor (IGF) receptor and the insulin-like effects of IGF-1 in the bony fish, Lates calcarifer.

The present work is part of a broad phylogenetic study of the insulin superfamily of peptides in lower vertebrates. In the bony fish barramundi (Lates calcarifer), the presence of IGF receptors were investigated in the liver by means of competitive binding studies. The results suggested the presence of a type 1-like but no type 2-like IGF receptor. We also demonstrated insulin-like effects of intraperitoneally injected recombinant human (rh)-IGF-1 in barramundi with rh-IGF-1 and rh-insulin showing similar effects with respect to induction of hypoglycemia and stimulation of incorporation of [14C]-glucose into muscle glycogen.

Animals↗