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Biomedical subjects

K A Armstrong

Publications and source records attributed to K A Armstrong.

17 recordsLinked to original sources
PubMed2006

Effect of aggressive risk factor modification on cardiac events and myocardial ischaemia in patients with chronic kidney disease.

OBJECTIVE: To examine whether aggressive risk factor modification in chronic kidney disease (CKD) can limit the development of new ischaemia or reduce cardiac events. METHODS: Patients with CKD were randomly assigned to either an aggressive risk factor modification strategy (targeted treatment of hypertension, dyslipidaemia, homocysteine, haemoglobin and phosphate) or standard care. An intention to treat analysis was performed on 152 patients who had baseline dobutamine stress echocardiography (DSE), including 107 who had follow-up DSE. Biochemical parameters, cardiac risk factors and investigations (ECG, two-dimensional echocardiography) were recorded at baseline. New ischaemia was classed as new or worsening stress wall motion abnormality between follow-up and baseline DSE. Patients were followed up for the development of new ischaemia or cardiac death, acute coronary syndrome and non-fatal myocardial infarction over 1.8 years. RESULTS: The development of new ischaemia was common but not different between the standard and aggressively treated groups (15 (21%) v 18 (23%), p = 0.8). Independent predictors of new ischaemia were older age, abnormal ECG, higher systolic blood pressure and lower serum high density lipoprotein cholesterol, but not treatment arm. The standard and aggressively treated groups did not differ in cardiac event rate (10% v 13%, p = 0.6) or all-cause mortality (10% v 19%, p = 0.2). In patients with an abnormal baseline DSE (non-diagnostic, scar or ischaemia), the event rate was similar (22% v 20%, p = 0.9). CONCLUSION: Aggressive risk factor modification in CKD does not limit the development of new ischaemia or reduce cardiac events in patients with an abnormal DSE.

Coronary Disease↗
PubMed1999

Ten-year follow-up of ovarian cancer patients after second-look laparotomy with negative findings.

OBJECTIVE: To determine long-term survival and predictors of recurrence in patients with platinum-treated ovarian cancer who were followed for 10 years after second-look laparotomy with negative findings. METHODS: Records were reviewed of 91 consecutive patients with negative findings on second-look laparotomy after platinum-based chemotherapy between January 1978 and January 1987. Statistical analysis used Kaplan-Meier survival curves, Cox proportional hazards, and multiple logistic regression. RESULTS: Mean age of patients was 57 (range 30-79) years. Distribution by stage and grade was as follows: stage I, ten; II, 18; III, 57; IV, six; grade 1, 18; 2, 28; 3, 45. Forty-seven of 91 women had optimal initial cytoreduction. Recurrence-free survival rates for all subjects were 75% at 2 years, 55% at 5 years, and 52% at 10 years. For women with stage I disease, the recurrence-free survival rate was 90% at 2, 5, and 10 years. For women with stage II disease, recurrence-free survival rates were 78, 72, and 66% at 2, 5, and 10 years, respectively. Patients with stage III or IV disease had recurrence-free survival rates of 72, 44, and 40% at 2, 5, and 10 years, respectively. Risk of recurrent disease was related to tumor stage (relative risk [RR] 2.02; 95% confidence interval [CI] 1.2, 3.3; P = .005), grade (RR 2.00; 95% CI 1.3, 3.2; P = .004), and presence of a residual tumor of more than 2 cm at the end of initial surgery (RR 3.19; 95% CI 1.2, 8.5; P = .02). CONCLUSION: Ovarian cancer patients face an appreciable risk of recurrence in the first 5 years after second-look laparotomy with negative findings after platinum-based chemotherapy, but those who remain disease free at 5 years have excellent long-term survival rates. Tumor stage, grade, and presence of a residual tumor of more than 2 cm after initial surgery are significant predictors of recurrence.

Adult↗
PubMed1999

Reproductive health needs: comparing women at high, drug-related risk of HIV with a national sample.

Women who inject drugs or have injection drug-using sex partners are at high risk of acquiring human immunodeficiency virus (HIV) infection and of transmitting HIV perinatally. Many of these women need standard reproductive health care services, specialized HIV care, pre- and postnatal care, and drug treatment, but the extent of the unmet need for such health services is unknown. Large-scale national surveys that estimate drug use do not include reproductive health topics and vice versa. In addition, such surveys typically employ a household sampling method that tends not to include drug-using women. This paper presents evidence from three convenience samples that a high-risk population of women who use drugs has limited access to reproductive health services, and that this population is not represented in the National Survey of Family Growth (NSFG), the national survey that informs public policy regarding reproductive health care in the United States. Policy makers would be well served by regular surveillance of the multiple service needs of women with HIV-risk-related behaviors.

Adolescent↗
PubMed1998

Selective synaptic plasticity within the cerebellar cortex following complex motor skill learning.

Complex motor skill learning, but not mere motor activity, leads to an increase in synapse number within the cerebellar cortex. The present experiment used quantitative electron microscopy to determine which synapse types were altered in number. Adult female rats were allocated to either an acrobatic condition (AC), a voluntary exercise condition (VX), or an inactive condition (IC). AC animals were trained to traverse an elevated obstacle course requiring substantial motor coordination to complete. VX animals were housed with unlimited access to running wheels and IC animals received no motor training but were handled briefly each day. Results showed the AC animals to have significantly more parallel fiber to Purkinje cell synapses than both the VX and IC animals. No other synapse type was significantly altered. Thus, the learning-dependent increase in synapse number observed within the cerebellar cortex is accomplished primarily through the addition of parallel fiber synapses.

Analysis of Variance↗
PubMed1998

Results of a domestic violence training program offered to the staff of urban community health centers. Evaluation Committee of the Philadelphia Family Violence Working Group.

INTRODUCTION: Domestic violence (DV) against women often goes unrecognized by health care providers due to multiple barriers. In an effort to increase screening, identification, and referral for services, the RADAR Training Project was created for the health care staff of 12 federally qualified community health centers (CHCs). METHODS: A two-phase evaluation was conducted to assess the intervention. Phase one evaluated the health care providers' perceived knowledge and comfort pre-training, post-training, and at 3 months follow-up. The second phase included a medical chart review of 4 CHCs to assess the rates of screening, documentation of abuse, assessment of safety, and referrals for help at baseline (6 months pre-training) as compared to the intervention period (6 months post-training). RESULTS: The health care providers' perceived level of knowledge and comfort increased significantly post-training and then later decreased at 3 months follow-up. The rate of screening for DV (25% vs. 5%), suspicion of DV (6% vs. 2%), completion of safety assessments (17% vs. 5%), and referrals (4% vs. 0%) increased significantly between the intervention and baseline periods. However, the rates of documentation of abuse did not change. CONCLUSIONS: This intervention was successful in increasing provider perceived knowledge and comfort; however, comfort decreased at follow-up. Additionally, the rates of screening and referrals increased 6 months post-training. Health care provider training and support and integrated quality assurance mechanisms may be necessary to increase the overall rate of these activities, and to sustain this effort over time. Further study is needed to identify effective methods to increase provider comfort regarding DV screening.

Adolescent↗
PubMed1994

SMART START: an option for adolescents to delay the pelvic examination and blood work in family planning clinics.

PURPOSE: The goal was to encourage earlier use of family planning services and effective birth control for teens. METHOD: In three federally-funded family planning clinics, the SMART START service model was offered to non-pregnant teens under 18. Teens making their first family planning visit to the clinics for family planning services had the option to delay the requisite pelvic examination and blood work following a careful medical and social history for up to 6 months while obtaining oral contraceptives and/or other non-prescriptive contraceptives. Each teen also received individualized counseling and follow-up telephone contacts. Survey and medical chart data were collected during the project period to evaluate the effects of SMART START on 151 teens. RESULTS: Of the 151 teens, 26% delayed the pelvic examination and 40% delayed the blood work. The delay of medical services did not result in negative health outcomes. Teens who elected to delay the pelvic examination returned to the clinic as frequently for revisits, they reported using condoms more consistently, they had fewer pregnancies and had similar STD rates compared with those not delaying. SMART START also found that ethnic factors correlated with deferring the blood work. CONCLUSIONS: SMART START offered teens options over how and when they receive reproductive health care services without withholding effective contraceptive methods. No serious complications of STDs resulted from the delay procedures. Expansion of the SMART START model to include both teen and adult populations is encouraged.

Adolescent↗
PubMed1988

Autoregulation of 2 micron circle gene expression provides a model for maintenance of stable plasmid copy levels.

The yeast plasmid 2 micron circle actively maintains high but stable copy levels in the cell, even though the plasmid confers no selective advantage to its host. To address the mechanism by which stable copy control is achieved, we have examined the level of expression of the genes resident on the yeast plasmid 2 micron circle as a function of the presence of proteins encoded by the plasmid. We find that transcription of the site-specific recombinase gene, FLP, is repressed at least 100-fold by the concerted action of the products of two other plasmid genes, REP1 and REP2. In addition, these products repress transcription of the REP1 gene itself. These results can be formulated into a consistent model for plasmid copy control.

DNA Nucleotidyltransferases↗
PubMed1986

Characterization of the gene products produced in minicells by pSM1, a derivative of R100.

At least ten polypeptides larger than 6 kilodaltons (K) are produced in minicells from the miniplasmid pSM1 in vivo. pSM1 (5804 bp) is a small derivative of the drug resistance plasmid R100 (ca. 90 kb) and carries the R100 essential replication region as well as some non-essential functions. Cloned restriction fragments of pSM1 and plasmids with deletions within pSM1 sequences were used to assign eight of the ten observed polypeptides to specific coding regions of pSM1. Two of these polypeptides were identified as RepA1 and RepA2, proteins encoded by the essential replication region of pSM1/R100. The nucleotide sequence consisting of 885 bp outside the essential replication region is presented here. This sequence contains an open reading frame, orf4, for a protein 22.9 K in size, and one of the pSM1-encoded polypeptides was identified as the orf4 gene product. Five additional polypeptides were shown to be the products of other open reading frames mapping outside the essential replication region. Specific functions have been assigned to four of these polypeptides and tentatively to the fifth.

Amino Acid Sequence↗
PubMed1984

A 37 X 10(3) molecular weight plasmid-encoded protein is required for replication and copy number control in the plasmid pSC101 and its temperature-sensitive derivative pHS1.

Nucleotide sequences were determined for a region essential for autonomous replication and partitioning of pSC101, a plasmid whose replication is dependent on the Escherichia coli dnaA gene product. The essential replication region contains one long coding sequence, rep101 , for a protein composed of 316 amino acids, and a polypeptide approximately 37 X 10(3) Mr in size was identified as the rep101 gene product. rep101 is preceded by two inverted repeat sequences, three directly repeated sequences and a region of high A + T content containing a sequence similar to the E. coli oriC consensus sequence. Because the lesions in seven replication-deficient insertion mutants, four mutants with increased copy number and one temperature-sensitive replication mutant occur within rep101 , the rep101 gene product must control pSC101 replication and copy number. par, a region adjacent to the replication region, which functions in stable plasmid inheritance, contains several inverted repeat sequences.

Autoradiography↗
PubMed1983

Site-dependent cleavage of pBR322 DNA by restriction endonuclease HinfI.

Cleavage of pBR322 DNA I by the restriction endonuclease HinfI is preferentially inhibited at specific HinfI cleavage sites. These sites in pBR322 DNA I have been identified and ordered with respect to the frequency with which they are cleaved. The HinfI site most resistant to cleavage in pBR322 DNA I is unique in that runs of G-C base pairs are immediately adjacent on both sites. Two differently permuted linear (DNA III) species were produced by cleavage with two different restriction endonucleases, PstI and AvaI. Only one of these linear molecules, that produced by PstI, exhibits the same preferential cleavage pattern as DNA I. The second linear species, that arising from AvaI digestion, shows pronounced relative inhibition of cleavage at the HinfI sites nearest the ends of the molecule (100 to 120 base pairs away, respectively). This result suggest that proximity to the termini of a linear DNA molecule might also influence preferential cleavage. The possibility of formation of stem-loop structures does not appear to influence preferential cleavage by HinfI.

Base Sequence↗
PubMed1977

Gene cloning and containment properties of plasmid Col E1 and its derivatives.

Colicinogenic plasmid E1 (Col E1) and Col E1 derivatives offer advantages as plasmid cloning vehicles with regard to both utility and biological containment. The Col E1 derivative pCR1 does not alter those essential characteristics of the enfeebled Escherichia coli strain x1776 that make this strain particularly useful as a host-vehicle system for recombinant DNA research.

Bile Acids and Salts↗
PubMed1976

Method for the isolation of Escherichia coli K-12 mutants deficient in essential genes.

We developed a general procedure for the induction and identification of mutations in chromosomal essential genes that are located in a diploid region of Escherichia coli K-12. The partial diploidy is conferred by an episome that is temperature sensitive for replication so that a mutant strain will form microcolonies at 42 C on complete media if an essential chromosomal gene in the diploid region is defective. Mutations identified by this procedure can be classified into cistrons by a complementation method devised for the purpose. To verify that the procedure works in practice, we fused an episome covering the rif region with an Ftslac+ and used the resulting temperature-sensitive episome to identify chromosomal mutations in essential functions near rif. As expected, a certain proportion of the mutations were in the rif gene, an essential gene that codes for the beta subunit of ribonucleic acid polymerase.

Conjugation, Genetic↗
PubMed1976

Essential genes in the metB-malB region of Escherichia coli K-12.

We isolated 25 independent mutants that are deficient in essential genes located in the metB-malB region of the Escherichia coli chromosome. The mutations were mapped within this region by using several F' factors and were also classified into 11 cistrons by complementation testing. There is clustering of mutations in essential genes within the metB-malB region.

Chromosome Mapping↗
PubMedDate not supplied

Barriers to family planning services among patients in drug treatment programs.

In July 1989, family planning services were integrated into 13 drug treatment programs in Philadelphia. To obtain information on the family planning needs of women in drug treatment programs, baseline interviews were conducted with 599 women. Three-quarters of these women had had a sexually transmitted disease, and although they were in a drug treatment program, 41 percent had injected drugs in the previous month. In addition, 62 percent of the women who were sexually active in the previous month had not used a contraceptive. Twelve months into the program, seven focus groups were conducted with 65 women and men to learn more about their opinions and attitudes related to contraceptives and family planning services in general. The discussions revealed that many of the participants were unsure what family planning services included, saw no need for such services or had had prior negative experiences with health care providers. There was also a great deal of misinformation about contraceptives and the effects they have on health.

Adolescent↗