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Biomedical subjects

S Lawrence

Publications and source records attributed to S Lawrence.

At least 37 records · Page 2Linked to original sources
PubMed1999

Successful obstetric outcome after simultaneous pancreas and kidney transplantation.

A 34-year-old woman became pregnant two years after having a simultaneous pancreas and kidney (SPK) transplantation, necessitated by type 1 diabetes and end-stage renal disease. The pregnancy was uneventful until 30 weeks' gestation, when she developed pancreatitis and a worsening of mild hypertension. A healthy 1700 g boy was delivered by caesarean section at 34 weeks' gestation. This is the first report of a successful pregnancy after SPK transplantation in Australia.

Adult↗
PubMed1999

Usefulness of a state-legislated, comparative database to evaluate quality in colorectal surgery.

PURPOSE: Colorectal surgery, a high-volume procedure, has been targeted for performance improvement to reduce length of stay. Specific postoperative quality indicators and readmission rates should be analyzed concomitantly to assure that adverse events are not associated with earlier discharge. METHODS: From July 1, 1990, to June 30, 1997, 1,218 consecutive patients who underwent transabdominal colorectal surgery were analyzed for length of stay, mortality, morbidity, and discharge disposition. Each patient was assigned an Admission Severity Group rating 0 to 4 using a hospital-based state-legislated software system (Atlas) to validate comparative performance internally and externally. Readmission data within 120 days of discharge were available for the last 678 consecutive patients from July 1, 1993, to June 30, 1997, using Lastword (computerized medical records). RESULTS: The annual frequencies of the 1,218 procedures were 173, 183, 175, 146, 167, 189, and 185, respectively, from July 1990 through June 1997. Severity distribution was 32 for Admission Severity Group 0, 517 for Admission Severity Group 1, 540 for Admission Severity Group 2, 128 for Admission Severity Group 3, and 1 for Admission Severity Group 4, with no annual difference (P = 0.012). There was a significant reduction in total length of stay of 3.1 (12.9-9.8) days during the seven years (P = 0.001). The overall operative mortality rate was 1.4 percent, and the morbidity was 2.6 percent, with no annual differences (P = 0.655 and P = 0.033, respectively). The disposition to home did not change (P = 0.21). Of the 678 patients followed up for readmission, 100 (14.7 percent) were readmitted within 120 days, with no annual difference (P = ().302). CONCLUSION: Mortality, morbidity, disposition, and readmission rates were not affected by a decreased length of stay after colorectal surgery.

Colonic Diseases↗
PubMed1999

Chronic active hepatitis B exacerbations in human immunodeficiency virus-infected patients following development of resistance to or withdrawal of lamivudine.

Lamivudine is a nucleoside analog with activity against human immunodeficiency virus (HIV) and hepatitis B virus (HBV). Patients coinfected with HIV and HBV may have hepatitis flares when lamivudine therapy is discontinued or when resistance of HBV to lamivudine emerges. This retrospective, descriptive study conducted in three tertiary care medical centers describes patients coinfected with HIV type 1 and HBV who presented with a spectrum of clinical and subclinical hepatitic responses to lamivudine withdrawal or resistance. One patient had fulminant hepatic failure and a second patient had subclinical hepatitis when lamivudine therapy was discontinued and a more efficacious antiretroviral regimen was substituted. Three patients had flares of hepatitis after 13 to 18 months of lamivudine therapy. Lamivudine withdrawal or emergence of lamivudine-resistant mutants in patients coinfected with HIV and HBV may result in severe hepatitis. Clinicians caring for patients with coinfection with HIV and HBV should be aware of the possibility that a hepatitis B flare may occur in previously asymptomatic carrier patients.

AIDS-Related Opportunistic Infections↗
PubMed1999

Replacing abdominally implanted defibrillators: effect of procedure setting on cost.

Although most ICDs are currently placed using a pectoral approach, there exists a large population of patients with abdominally implanted ICDs who will require device replacement due to a depleted battery. The purpose of this study was to compare the cost, convalescence, and complication rate of replacing abdominally implanted ICDs in the OR versus the EP laboratory. Between August 1993 and September 1994, we prospectively enlisted nine consecutive patients who presented for their second ICD generator replacement and who had a prior generator replacement in the OR 3-4 years earlier. The mean age of the patients was 63 +/- 17 years and their mean ejection fraction was 37% +/- 15%. ICD replacement was performed in the EP laboratory and consisted of explanting the old device, electronic interrogation of the lead system, and confirmation of defibrillation thresholds prior to implanting a new device. Local anesthesia was provided by lidocaine infiltration and sedation was achieved with intravenous (i.v.) midazolam and fentanyl. Following the procedure, the patients were returned to an outpatient monitored setting for 4 hours and were then discharged. Comparisons of the health care charges for the same procedure performed in the two different settings revealed a significant reduction in physician fees (from $3,621 +/- $556 to $2,179 +/- $577, P < 0.05), in hospital charges (from $5,811 +/- $1,102 to $2,306 +/- 696, P < 0.05), and in total charges (from $9,431 +/- $1,375 to $4,541 +/- $1,010, P < 0.05), exclusive of ICD cost, when the procedure was performed on an outpatient basis in the EP laboratory. Inpatient days averaged 3.0 +/- 0.3 when the procedure was performed in the OR. On long-term follow-up there were no complications following abdominal ICD generator replacement in the OR (mean follow-up, 39 +/- 2 months) or in the EP laboratory (mean follow-up, 42 +/- 4 months). Thus, ICD replacements in the EP laboratory cost less than in the OR due to significantly lower physician fees, hospital charges, and a shorter postprocedural convalescence.

Abdomen↗
PubMed1998

Searching the world wide Web

The coverage and recency of the major World Wide Web search engines was analyzed, yielding some surprising results. The coverage of any one engine is significantly limited: No single engine indexes more than about one-third of the "indexable Web," the coverage of the six engines investigated varies by an order of magnitude, and combining the results of the six engines yields about 3.5 times as many documents on average as compared with the results from only one engine. Analysis of the overlap between pairs of engines gives an estimated lower bound on the size of the indexable Web of 320 million pages.

Journal Article↗
PubMed1998

Altitude training at 2690m does not increase total haemoglobin mass or sea level VO2max in world champion track cyclists.

Haemoglobin mass (Hb mass), maximum oxygen consumption (VO2max), simulated 4000 m individual pursuit cycling performance (IP4000), and haematological markers of red blood cell (RBC) turnover were measured in 8 male cyclists before and after (A) 31 d of altitude training at 2690 m. The dependent variables were measured serially after altitude on d A3-4, A8-9 and A20-21. There was no significant change in Hb mass over the course of the study and VO2max at d A9 was significantly lower than the baseline value (79.3 +/- 0.7 versus 81.4 +/- 0.6 ml x kg(-1) x min(-1), respectively). No increase in Hb mass or VO2max was probably due to initial values being close to the natural physiological limit with little scope for further change. When the IP4000 was analysed as a function of the best score on any of the three test days after altitude training there was a 4% improvement that was not reflected in a corresponding change in VO2max or Hb mass. RBC creatine concentration was significantly reduced after altitude training, suggesting a decrease in the average age of the RBC population. However, measurement of reticulocyte number and serum concentrations of erythropoietin, haptoglobin and bilirubin before and after altitude provided no evidence of increased RBC turnover. The data suggest that for these elite cyclists any benefit of altitude training was not from changes in VO2max or Hb mass, although this does not exclude the possibility of improved anaerobic capacity.

Adult↗
PubMed1998

Managerialism, information technology and health reform in New Zealand.

Recent health reform in New Zealand has transformed public hospitals and related health services into Crown Health Enterprises (CHEs), which have a statutory objective to operate as successful and efficient businesses. Examines managerialist interpretations of a proposed executive information system (EIS) at one CHE. Arguably, the use of computerized information systems signals managerial competence and rationality, and there was an implicit assumption among senior CHE managers that "business-like" and "efficient" management required the use of information technology. In the end, in the context of continuing organizational restructuring, the EIS was never implemented.

Benchmarking↗
PubMed1997

Decrease of very late activation antigen-4 and CD36 on reticulocytes in sickle cell patients treated with hydroxyurea.

Sickle cell disease (SCD) is characterized by repeated vaso-occlusive events, which result in substantial morbidity. Abnormal adhesion of sickle red blood cells (RBC) to the vascular endothelium is postulated to play a role in the pathogenesis of vaso-occlusion. Two adhesion receptors, very late activation antigen-4 (VLA-4) and CD36, are found in unusually high numbers on sickle cell reticulocytes and do mediate adhesion of sickle RBC to endothelium. Hydroxyurea (HU) therapy results in fewer vaso-occlusive episodes, and we postulated that HU-related modulation of VLA-4 and CD36 receptors may contribute to its clinical benefit. Using flow cytometry, eight patients were followed from the onset of HU treatment through a mean treatment length of 200 +/- 49 days. Mean corpuscular volume and percent fetal hemoglobin (Hb F) increased from 87% +/- 6% to 98% +/- 9% and 6.6% +/- 3.9% to 12.7% +/- 5.6%, respectively. The percentage of reticulocytes expressing VLA-4 decreased from 29.0% +/- 5.9% to 14.9% +/- 2.3% (P = .0003). Two thirds of the total decrease in VLA-4 expression occurred after 10 weeks of HU and plateaued by 20 weeks. Changes in VLA-4 expression occurred before substantial increases in Hb F. The percentage of reticulocytes expressing CD36 decreased from 55.3% +/- 6.4% to 42.6% (P = .0046). Changes in adhesion receptor expression were not caused by a decrease in reticulocytosis with HU therapy. This report is the first to associate a decrease in adhesion receptor expression with a therapy known to reduce the clinical severity of SCD.

Adolescent↗
PubMed1997

Muscle phosphocreatine repletion following single and repeated short sprint efforts.

Phosphocreatine (PCr) repletion following either single (1x6 s, n=7) or repeated (5x6 s, departing every 30 s, n=8) maximal short sprint cycling efforts was measured in separate groups of trained subjects. Muscle biopsies (vastus lateralis) were taken pre-exercise before warming up, and then at 10 s, 30 s and 3 min post-exercise. After the 1 x 6 s sprint PCr concentration was respectively, 55% (10 s; P<0.01), 69% (30 s; P<0.01) and 90% (3 min; NS) of the pre-exercise value (mean+/-SD) (81.1+/-7.4 mmol x kg(-1) DM), whereas after the 5x6 s sprints, PCr concentration was, respectively, 27% (10 s; P<0.01), 45% (30 s; P<0.01) and 84% (3 min; P<0.01) of the pre-exercise value (77.1+/-4.9 mmol x kg(-1) DM). PCr concentration was correlated with muscle lactate at 30 s (r=-0.82; P<0.05) and 3 min of recovery (r=-0.94; P<0.01) for the 1x6 s sprint, but not for the 5x6 s sprints. The extent of PCr repletion was significantly greater after the 5x6 s sprints than the 1x6 s sprint between both 10 s and 30 s and 30 s and 3 min, despite lower PCr levels at 10 s, 30 s and 3 min following the 5x6 s sprints. Full repletion of PCr is likely to take longer after repeated sprints than single short sprints because of a greater degree of PCr depletion, such that replenishment must commence from lower PCr levels rather than because of slower rates of repletion.

Adult↗
PubMed1996

Nasal continuous positive airway pressure treatment: current realities and future.

Nasal continuous positive airway pressure (CPAP) is a highly effective treatment for obstructive sleep apnea syndrome. The apnea/hypopnea index (AHI) is reduced 10-fold, but the patient dropout rate is up to 30%, and usage is typically < 5 hours per night. Titration, designed to make the best trade-off between effectiveness and side effects, is expensive. Autotitrating devices make this trade-off on a minute-by-minute basis, potentially reducing mean pressure delivery, reducing side effects, and increasing compliance. The aim of this study was to test the effectiveness of the AutoSet self-adjusting nasal CPAP system (ResMed, Sydney, Australia) in eliminating obstructive events and normalizing the arousal index. Forty-five subjects (41 males and 4 females with AHI) values of > 20/hour were recruited, with written informed consent. Subjects slept for a diagnostic night, followed by a treatment night, in the laboratory, using the AutoSet system with full polysomnographic monitoring of respiratory and sleep variables. Arousals were scored using ASDA criteria. Hypopneas were scored when there was a 50% reduction in ventilation for > 10 seconds, associated with a 4% drop in oxygen saturation. For comparison, the ASDA arousal index in 16 normal subjects (without nasal CPAP) is provided. Results are given as mean +/- standard error of the mean. AHI was reduced from 55 +/- 3 to 1.5 +/- 0.35 events/hour (p < 0.0001). The arousal index was reduced from 65 +/- 3 to 18 +/- 2 events/hour (p < 0.0001), identical to the value in the 16 healthy normal subjects. There was a 158% +/- 21% increase in slow-wave sleep (p = 0.01) and a 186% +/- 27% increase in rapid eye movement sleep (p = 0.013). The AutoSet self-adjusting nasal CPAP system adequately treats obstructive sleep apnea syndrome on the first night under laboratory conditions.

Female↗
PubMed1996

Controlled retainer-screw access placement for screw-retained implant prosthesis.

An implant-supported prosthesis is often secured to the underlying gold cylinders by retaining screws. There must be access to these screws from the oral surface of the prosthesis. Conventional preparation of this access is from the oral surface. This approach is difficult because the underlying gold cylinder is obscured. It may be damaged by a rotary cutting instrument as the access is prepared above it, because the cylinder cannot be seen during the preparation. Alternatively, the access hole may be unnecessarily enlarged in an attempt to find the cylinder. This loss of structure may weaken the prosthesis. A new approach, using 18-gauge stainless steel wire as a rotary cutting instrument, permits preparation of the access chamber from the intaglio surface of the prosthesis. This reduces risk of damage to the gold cylinder and is less destructive to the overlying material.

Bone Screws↗
PubMed1996

Allelic association of gene markers on chromosomes 5q and 11q with atopy and bronchial hyperresponsiveness.

To investigate genetic factors in asthma and atopy, we sought allelic associations for 12 markers near candidate loci for serum total, immunoglobulin E (IgE), and bronchial hyperresponsiveness (BHR) to inhaled histamine in 131 families comprising 685 individuals, selected randomly without regard to atopy or asthma. Nonparametric linkage and association analyses were performed with the Nonparametric Analysis of Lineage and Association (NOPAR) program, and parametric analyses were performed with the Complex Inheritance with Diathesis and Severity (COMDS) program on an ordered polychotomy of ranked scores. On chromosome 11q, allele 168 at the D11S527 locus was significantly associated with BHR (p<0.0003) but not with log IgE. At the D11S534 locus, allele 235 was significantly associated with log IgE (p = 0.007) but not with BHR. Both D11S527 and D11S534 were too distant from the gene encoding the high-affinity IgE receptor FcepsilonRIbeta to account for the association. At the interleukin-9 (IL-9) locus, the 118 allele showed significant association with serum total IgE (p<0.003) but not with histamine BHR. Parametric tests are more conservative, perhaps because they demand consistency with mendelian inheritance and tight linkage. These findings provide support for the view that both chromosomes 5 and 11 may contain genes relevant to asthma and atopy, a possible candidate being the interleukin-4 (IL-4) gene cluster. Because these associations are extremes in a large number of tests, they require confirmation in other samples.

Adolescent↗