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Biomedical subjects

D Dwyer

Publications and source records attributed to D Dwyer.

At least 37 records · Page 2Linked to original sources
PubMed1998

Polymerase chain reaction and restriction fragment length polymorphism analysis of varicella-zoster virus isolates from the United States and other parts of the world.

A polymerase chain reaction (PCR) assay that identifies and differentiates wild-type (wt) and vaccine strains of varicella-zoster virus (VZV) was used to determine if VZV strains with restriction fragment length polymorphisms resembling those of the Japanese Oka vaccine strain were present in the wt pool outside of Japan. Virus samples (n = 114) from patients with chickenpox and zoster from various parts of the United States and Australia were analyzed. The assay correctly identified 113 samples as wt strain. The 1 sample identified as Oka vaccine strain came from a child with leukemia who developed a vaccine-associated rash after receiving the live attenuated varicella vaccine. At this point, there is no evidence that wt strains resembling the vaccine are circulating outside of Japan. This indicates that this PCR assay can be utilized to distinguish rashes due to vaccine and wt VZV.

Australia↗
PubMed1998

Pseudo-outbreak of tuberculosis in an acute-care general hospital: epidemiology and clinical implications.

A 10-fold increase in patients with Mycobacterium tuberculosis-positive specimens in one hospital laboratory prompted an investigation. Clinical and epidemiological data, along with M tuberculosis DNA fingerprinting results, indicated that laboratory contamination led to nine false-positive M tuberculosis cultures. Pseudo-infection should be considered in patients with unusual tuberculosis presentations, negative acid-fast bacilli smears, and only one positive culture with a low colony count.

Cross Infection↗
PubMed1995

Genomic structure of an attenuated quasi species of HIV-1 from a blood transfusion donor and recipients.

A blood donor infected with human immunodeficiency virus-type 1 (HIV-1) and a cohort of six blood or blood product recipients infected from this donor remain free of HIV-1-related disease with stable and normal CD4 lymphocyte counts 10 to 14 years after infection. HIV-1 sequences from either virus isolates or patient peripheral blood mononuclear cells had similar deletions in the nef gene and in the region of overlap of nef and the U3 region of the long terminal repeat (LTR). Full-length sequencing of one isolate genome and amplification of selected HIV-1 genome regions from other cohort members revealed no other abnormalities of obvious functional significance. These data show that survival after HIV infection can be determined by the HIV genome and support the importance of nef or the U3 region of the LTR in determining the pathogenicity of HIV-1.

Adult↗
PubMed1995

Utility of transvenous liver biopsies and wedged hepatic venous pressure measurements in sixty marrow transplant recipients.

Sixty marrow transplant recipients with liver dysfunction underwent transvenous liver biopsy and measurement of the hepatic venous pressure gradient. Biopsies were done on 29 patients using a Cook needle inserted through the jugular vein, on 30 patients through the femoral vein with a Mansfield biopsy forceps, and on 1 patient using both instruments. The average number of evaluable portal spaces was 4.0 for aggregated Cook needle specimens and 5.2 for Mansfield forceps specimens. The average number of central venules was 2.6 for Cook needle specimens and 3.5 for Mansfield specimens. Tissue obtained with the Mansfield forceps had crush artifact, especially along the edges, making assessment of bile ducts more difficult than in Cook needle specimens. Liver histology aided management in 53/60 patients by confirming the clinical diagnosis in 24 (40%) and by providing additional diagnoses in 29 (48%). Hepatic venous pressure gradient > 10 mmHg correlated with a histologic diagnosis of veno-occlusive disease (P = 0.001); this gradient value provided 91% specificity and 86% positive predictive value. Eleven patients had bleeding complications, 9 after Cook needle biopsy and 2 after Mansfield forceps biopsy. There were 3 procedure-related deaths, 2 from intraperitoneal bleeding after Cook needle biopsy and 1 from femoral vein bleeding after Mansfield biopsy. We conclude that transvenous liver biopsy and pressure measurements provide useful diagnostic information in marrow transplant patients with liver disease. In our hands, the Mansfield forceps was associated with a lower risk of intra-abdominal bleeding and capsular perforation of the liver while providing adequate histology for diagnosis. Hepatic venous pressure gradients > 10 mmHg were highly specific for a diagnosis of veno-occlusive disease in this patient population.

Biopsy↗
PubMed1995

Typhoid fever in the park: epidemiology of an outbreak at a cultural interface.

The number of reported outbreaks of typhoid fever in the United States has recently increased. Only six were reported from 1980-1989, but seven outbreaks were reported in 1990. In August 1990, health officials in Montgomery County, Maryland, were notified of two cases of typhoid fever among persons who had attended both a family picnic attended by 60 persons and a Latin Food Festival attended by 100,000 people. We obtained interviews, blood and stool cultures, and Vi serologies from attendees at and food handlers for the picnic. We defined cases as culture-confirmed or probable. Of the 60 picnic attendees, 24 (40%) had cases, of which 16 were culture confirmed. Those who ate potato salad were at increased risk of disease (17/32 vs. 6/28, relative risk [RR] = 2.5, 95% confidence interval [CI] 1.1-5.4). Picnic attendees who also attended the Latin Food Festival were not at significantly greater risk of disease than those who did not, (11/22 vs. 13/38, RR = 1.5, CI = 0.8-2.7) and we found no evidence of disease among other festival attendees. The potato salad was prepared with intensive handling and without adequate temperature control by a recent immigrant from El Salvador who was asymptomatic, did not attend the picnic, had Salmonella typhi (S. typhi) in her stool, and had elevated Vi antibodies, strongly suggestive of the carrier state. Outbreaks of typhoid fever are a threat for cosmopolitan communities. While currently available control measures are unlikely to prevent all outbreaks, thorough investigation can identify previously unrecognized carriers.

Adolescent↗
PubMed1994

Postnatal care: teamwork in the community.

To offer continuity of care as recommended by Changing Childbirth, close communication between midwives and health visitors is important. Selective postnatal visiting allows continuation of visits after the tenth day and encourages communication between the midwife and health visitor. Good communication between a midwife and health visitor can ensure that a framework of care is provided to support mothers as they develop self-confidence and independence. To ensure continuity of care, midwives should involve health visitors during the antenatal period wherever possible. Formal and informal lines of communication between midwives and health visitors should be encouraged.

Communication↗
PubMed1993

Isoflurane versus fentanyl: hemodynamic effects in cancer patients treated with anthracyclines.

Cancer patients treated with anthracycline derivatives are at risk for perioperative cardiovascular decompensation. The authors studied hemodynamic performance before, during, and after laparotomy in 14 anthracycline-treated patients with ovarian carcinoma. General anesthesia was maintained with 70% N2O in O2, and patients were randomized to receive supplementation with either isoflurane, 0.59% end-tidal +/- 0.04 (mean +/- SE), or fentanyl, 2.67 micrograms/kg +/- 0.49 as a loading dose, and a total dose of 7.16 micrograms/kg +/- 0.71. The degree of hemodynamic stability relative to the baseline was assessed. There was no obvious superiority of either technique prior to the skin incision. However, during and immediately after surgery, a clearer tendency for isoflurane-N2O to result in better hemodynamic stability was found. Isoflurane-N2O demonstrated significantly smaller change scores in systemic vascular resistance (SVR) and cardiac index (CI). At the start of surgery, the isoflurane-N2O change in SVR was 228.08 dyne.sec.cm-5 compared to 479.58 for the fentanyl patients, (P = 0.002); at the end of surgery the corresponding means were -12.09 and 703.14 dyne.sec.cm-5, respectively, (P = 0.002). Isoflurane-N2O was associated with significantly greater CI stability in the early postoperative period: the isoflurane-N2O mean change was -0.081 L/min/m2, versus -0.993 for the fentanyl-N2O patients, (P = 0.005). The authors conclude that anthracycline-treated patients who do not have overt evidence of cardiomyopathy can be safely anesthetized with either anesthetic technique. However, during surgery and in the early postoperative period, an isoflurane-N2O technique appears to offer better hemodynamic stability.

Acid-Base Imbalance↗
PubMed1992

Diagnostic sensitivity of the laboratory tests in myasthenia gravis.

The diagnostic sensitivity of three laboratory tests [serum antiacetylcholine receptor antibody (AChR-ab) assay, the repetitive nerve stimulation (RNS) test, and, the single fiber EMG (SFEMG)] for myasthenia gravis (MG) was compared in 120 patients. In all cases, at least one of the tests was abnormal. SFEMG was the most sensitive test, being abnormal in 92% of cases, followed by the RNS test (77%) and the AChR-ab assay (73%). SFEMG was abnormal in all cases with negative AChR-ab and RNS tests, in 97% of cases with negative AChR-ab assay, in 89% of cases with negative RNS test, and in 89% of cases with mild MG. We conclude that one of these three tests is abnormal in all cases of MG, and that the SFEMG is most sensitive in the diagnosis of MG.

Autoantibodies↗
PubMed1992

Esmolol infusion during nitroprusside-induced hypotension: impact on hemodynamics, ventricular performance, and venous admixture.

The impact of esmolol infusion on hemodynamics, ventricular performance, venous admixture, sympathoadrenal, and renin-angiotensin system responses during sodium nitroprusside (SNP)-induced hypotension was studied in 11 patients undergoing lymph node dissection during general anesthesia with 60% nitrous oxide and fentanyl. Radial arterial and thermistor-tipped pulmonary catheters were employed for hemodynamic monitoring. Arterial and mixed venous blood gas tensions, arterial plasma renin activity (PRA), and plasma catecholamine levels were measured. Derived hemodynamic parameters and venous admixture (Qs/Qt) data were obtained from standard equations. Transesophageal echocardiography (6 patients) was used to assess left ventricular performance using the relationship between end-systolic wall stress (ESWS) and velocity of circumferential shortening (VCFC). After surgical incision, arterial hypotension was induced with SNP alone. Esmolol was infused at each of the following rates in sequence: 200, 300, and 400 micrograms/kg/min. Each esmolol infusion lasted 20 minutes and the SNP dose was adjusted to maintain MAP at 55 to 60 mm Hg. The mean dose of SNP required to induce hypotension was 5.5 micrograms/kg/min +/- 0.5 SE. Compared to prehypotension values, SNP induced significant increases in Qs/Qt and reductions in PaO2, systemic vascular resistance (SVR), and stroke volume index (SVI). Esmolol infusion caused dose-dependent (highest with 400 micrograms/kg/min) reductions in the SNP requirement, heart rate (HR), SVI, Qs/Qt, and PRA, and also led to significant increases in SVR and left ventricular (LV) internal diameter in diastole as well as systole. Furthermore, esmolol infusion was associated with a dose-dependent downward and leftward shift of the ESWS versus VCFC relationship, implying diminished contractility.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1992

Functional screening of lower-limb amputees: a role in predicting rehabilitation outcome?

The Functional Independence Measure (FIM), a single-score instrument used to measure independent functioning in six areas of basic self-care skills, was used to evaluate 68 patients following lower-limb amputation. Patients in a rehabilitation hospital were assessed with the FIM upon admission and discharge. Admission scores averaged 52.7, ranging from 25.2 to 70.0. Patients scoring in the lowest and highest quartiles were compared: no remarkable gender, ethnic, or age differences were evident. Persons with the lowest scores (ie, lowest functioning) had a higher prevalence of hypertension, coronary artery disease, and noninsulin-dependent diabetes mellitus. The success of rehabilitation in patients in the lower two quartiles upon admission was variable and not predicted well by the FIM. In contrast, predictability of rehabilitation success was high in patients functioning higher at admission, the majority achieving near-perfect scores by discharge. Length of hospitalization appeared to be largely unrelated to the net difference in FIM scores over the course of hospitalization.

Activities of Daily Living↗
PubMed1990

Neurocysticercosis: an under-recognized cause of neurological problems.

Neurocysticercosis is an uncommon, and under-recognized condition in Australia. Changes in immigration patterns may lead to a rising prevalence in this country. Epilepsy is the most common presentation, but it has many other variable forms of neurological manifestations. Eight cases are described, all in immigrants from Eastern Europe, Asia or Central America; the disease was presumably acquired before arrival in Australia. Six patients had symptoms for two to 30 years before the diagnosis was made and, in some cases, the first neurological manifestations appeared decades after initial infection. In patients with active disease a successful outcome followed therapy with praziquantel and corticosteroids. We advise that all patients requiring treatment be admitted to hospital for corticosteroid and anticonvulsant therapy to minimize the clinical deterioration which may result from therapeutic destruction of larvae.

Adolescent↗
PubMed1990

Signal-regulator interactions. Genetic analysis of the effector binding site of xylS, the benzoate-activated positive regulator of Pseudomonas TOL plasmid meta-cleavage pathway operon.

This study reports a genetic analysis of the interactions between a positive regulator of gene expression and its effector molecules. Transcription of the TOL plasmid meta-cleavage pathway operon is specifically stimulated by the XylS protein positive regulator either through activation of this regulator by benzoate effectors or through its hyperproduction. One xylS mutant that exhibits constitutive expression of the operon promoter has been characterized, together with six mutants encoding altered XylS proteins that recognize as effectors benzoate analogues that are non-effectors for the XylS wild-type protein. The changes in two mutant regulators are located at the N-terminal end of the protein, within a putative beta-pleated domain. These mutant proteins exhibit a markedly increased affinity for normal benzoate effectors, with K's values fivefold to 60-fold lower than those of the wild-type XylS protein. They are additionally activated by new effectors having certain substituents at position 2, 3 and 4 of the aromatic ring. Two other mutant proteins recognize new effectors having substituents at position 4 and 5 of the aromatic ring, and contain mutations at their C-terminal end within a putative alpha-helix-rich domain. Three other mutations, one of which leads to constitutive expression from Pm, each result in an amino acid change in the central region of the regulator. These findings suggest but do not prove that the effector binding pocket of the XylS protein may be composed of two or more non-contiguous segments of its primary structure. The XylS protein exhibits homology with the AraC protein of Escherichia coli, a protein that stimulates transcription from ara promoters when it is activated by arabinose or benzoate. Mutations influencing effector activation of the XylS protein characterized in this study are all located in regions exhibiting a high degree of homology with the corresponding aligned sequence of AraC protein.

Amino Acid Sequence↗
PubMed1989

Oxidative modifications to crystallins induced in calf lenses in vitro by hydrogen peroxide.

Calf lenses which are incubated in solutions of 1-150 mM H2O2 for 24 hr remain clear at 20 degrees C. While insoluble lens protein increases by at most 2-3%, we find extensive oxidation of exposed protein thiols, major shifts in the size distribution of crystallins, and progressive generation of more acidic polypeptides. Some of these oxidative modifications are reversible with reducing agent. beta H-Crystallins are particularly susceptible to oxidation: disulfide-bonded soluble aggregates form at low H2O2 levels, while irreversible dissociation to beta L-crystallins occurs at high H2O2 concentration. The gamma-crystallins are particularly prone to charge modification. In contrast, the size and charge distributions of alpha-crystallins appear to be virtually unaffected by H2O2.

Animals↗