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Biomedical subjects

S Johnston

Publications and source records attributed to S Johnston.

At least 37 records · Page 2Linked to original sources

Antiretroviral treatment simplification with nevirapine in protease inhibitor-experienced patients with hiv-associated lipodystrophy: 1-year prospective follow-up of a multicenter, randomized, controlled study.

BACKGROUND: Simpler and less toxic antiretroviral strategies are needed to maximize treatment compliance without sacrificing potency, at least for drug-experienced HIV-infected patients currently on regimens containing protease inhibitors (PIs). Small nonrandomized studies have suggested a beneficial role of PI-sparing regimens on lipodystrophy. OBJECTIVES: To assess the virologic, immunologic, and clinical benefit of switching the PI to nevirapine in patients with HIV-associated lipodystrophy and sustained viral suppression before entry in the study. DESIGN: Open-labeled, prospective, randomized, multicenter study. SETTING: Seven reference inpatient centers for HIV/AIDS in Spain. PATIENTS: One hundred six HIV-infected adults with clinically evident lipodystrophy who sustained HIV-RNA suppression for at least 6 months with PI-containing antiretroviral combinations. INTERVENTION: Replacement of the PI with nevirapine during 48 weeks (Group A) versus continuing the prior PI (Group B). MEASUREMENTS: Several virologic and immunologic analyses, standard and specific biochemical tests, and anthropometric and dual X-ray absorptiometry measurements. RESULTS: At week 48, an HIV-1 RNA level <400 copies/ml was maintained in 79% and 77% of patients in Groups A and B, respectively, whereas 74% and 72% of patients had viral load levels <50 copies/ml. Absolute CD4+ counts significantly increased in both groups compared with baseline values, and a significant decrease in CD38+CD8+ cells was observed in Group A (p <.01) but not in group B. Overall, no significant changes in anthropometric or body shape measurements were found after 48 weeks. Fasting total cholesterol and triglyceride levels decreased in Group A (but not in Group B) compared with baseline values (p <.05), although no significant differences were seen between groups at the end of the study. Subjects in Group A reported a better quality of life (QOL) index than controls (p <.001), with the main reason reported being the greater simplicity of the new drug regimen. CONCLUSIONS: Protease inhibitor-sparing regimens, including nevirapine, seem to be an effective alternative for PI-experienced patients. Nevirapine-based triple therapies allow maintained control of HIV-1 RNA levels and improve the immunologic response at 48 weeks of follow-up in patients with prior sustained virologic suppression. The switch to nevirapine significantly improved the lipidic profile in Group A, although there were no differences between groups at the end of the study. Additionally, no significant changes were seen in terms of lipodystrophy-related body shape changes 1 year after the PI substitution. Finally, nevirapine-containing regimens have a simpler dosing schedule, and this facilitates high adherence and improves QOL.

Adult↗

A short formal synthesis of squalamine from a microbial metabolite.

A short formal synthesis of squalamine is described, utilizing the biotransformation product 2, which is available in one step from commercially available 3-keto-23,24-bisnorchol-4-en-22-ol (1). Regioselective C-22 oxidation and C-24 sulfation of the corresponding alcohols in the presence of a free C-7 alcohol make for an efficient preparation of squalamine intermediate 11.

Angiogenesis Inhibitors↗

Filamentous growth of Saccharomyces cerevisiae is regulated by manganese.

The Candida albicans INT1 gene is a virulence factor that contributes to both adhesion and filamentous growth of the fungus. Expression of INT1 in the budding yeast Saccharomyces cerevisiae directs both adhesion and filamentous growth. Because Int1p contains two predicted divalent cation-binding motifs, we asked whether divalent cations are important for the role of Int1p in filament formation. In this study, we found that INT1-induced filamentous growth (I-IFG) is sensitive to the divalent cation chelator EDTA and that this EDTA sensitivity can be ameliorated by the addition of Mn(2+), but not Mg(2+) or Ca(2+) ions. The addition of MnCl(2) restored both the proportion of cells forming filaments and the length of filaments formed. Expression of INT1 in S. cerevisiae mutants that reduce the intracellular concentration of Mn(2+) did not affect I-IFG. Interestingly, the Mn(2+) dependence of I-IFG is not dependent upon the presence of the putative divalent cation-binding domains found in INT1. Rather, we found that polarized growth induced by mutations in CDC12 and CLA4 or by expression of excess SWE1 was also sensitive to EDTA treatment and was restored by the addition of MnCl(2) but not by the addition of CaCl(2). Thus, our results suggest that in S. cerevisiae polarized growth is dependent upon the presence of Mn(2+) ions.

Amino Acid Motifs↗

Video-assisted thoracoscopic surgery in the management of loculated empyema.

BACKGROUND: Fibropurulent empyema (stage II of Light) does not respond to antibiotic therapy and simple drainage. If the condition is inadequately treated, restrictive pulmonary deficit develops, necessitating thoracotomy and decortication. We report our experience with the videoscopic management of stage II and limited stage III disease. METHODS: Ten consecutive patients underwent videoscopic debridement of fibropurulent empyema; three of them required removal of limited visceral and parietal rind. RESULTS: The mean operating time was 42 +/- 8.1 min. Postoperative pyrexia and leucocytosis settled within 4.2 +/- 2.1 days and 13.1 +/- 3.2 days, respectively. Intercostal chest tubes were removed by 4.5 +/- 1.0 days. The mean fall in hematocrit following surgery was 4.9%. Parenteral analgesics were required for 1.0 +/- 0.5 days and oral analgesics for 3 +/- 1.6 days. The mean postoperative stay was 11 +/- 8.1 days. No patient required any further intervention. CONCLUSIONS: Videoscopic debridement of empyema produces excellent results, with minimal patient morbidity and a short hospital stay. We recommend it as the preferred method for first-line management of fibropurulent (stage II) empyema.

Adult↗

Randomized controlled trial of changes in dietary carbohydrate/fat ratio and simple vs complex carbohydrates on body weight and blood lipids: the CARMEN study. The Carbohydrate Ratio Management in European National diets.

OBJECTIVE: To investigate the long-term effects of changes in dietary carbohydrate/fat ratio and simple vs complex carbohydrates. DESIGN: Randomized controlled multicentre trial (CARMEN), in which subjects were allocated for 6 months either to a seasonal control group (no intervention) or to one of three experimental groups: a control diet group (dietary intervention typical of the average national intake); a low-fat high simple carbohydrate group; or a low-fat high complex carbohydrate group. SUBJECTS: Three hundred and ninety eight moderately obese adults. MEASUREMENTS: The change in body weight was the primary outcome; changes in body composition and blood lipids were secondary outcomes. RESULTS: Body weight loss in the low-fat high simple carbohydrate and low-fat high complex carbohydrate groups was 0.9 kg (P < 0.05) and 1.8 kg (P < 0.001), while the control diet and seasonal control groups gained weight (0.8 and 0.1 kg, NS). Fat mass changed by -1.3kg (P< 0.01), -1.8kg (P< 0.001) and +0.6kg (NS) in the low-fat high simple carbohydrate, low-fat high complex carbohydrate and control diet groups, respectively. Changes in blood lipids did not differ significantly between the dietary treatment groups. CONCLUSION: Our findings suggest that reduction of fat intake results in a modest but significant reduction in body weight and body fatness. The concomitant increase in either simple or complex carbohydrates did not indicate significant differences in weight change. No adverse effects on blood lipids were observed. These findings underline the importance of this dietary change and its potential impact on the public health implications of obesity.

Adult↗

Protracted venous infusion 5-fluorouracil in combination with subcutaneous interleukin-2 and alpha-interferon in patients with metastatic renal cell cancer: a phase II study.

Our purpose was to assess the activity of alpha-interferon (IFN-alpha), interleukin-2 (IL-2) and 5 fluorouracil (5FU) administered by protracted venous infusion (PVI) as opposed to bolus injection. 55 patients with advanced renal cell cancer were treated as follows: IL-2 and IFN-alpha according to the schedule originally described by Atzpodien, with PVI 5FU 200 mg m(-2)day(-1)during weeks 5-9. 42 patients (76%) were of moderate or poor prognosis as defined by previous studies. The response rate by intention to treat was 31% (17 of 55, three complete response, 14 partial response; 95% CI = 19-45%) and in evaluable patients (completed one cycle, n = 42), it was 40% (95% CI = 26-57%). In addition, 24% (13 of 55) patients achieved disease stabilization. The overall median survival was 11 months with a 1-year survival of 45%. The median survival for evaluable patients was 18 months with 1- and 2-year survivals of 60% and 40% respectively. The median survival of responding patients was 31 months and the three patients achieving complete response remain progression-free at 14+, 18+ and 23+ months. Evaluable patients with poor prognostic features achieved a response rate of 54% and median survival of 18 months. Toxicity was significant yet manageable with 12 patients unable to complete one cycle due to side-effects and 36% experiencing grade 3-4 toxicities. The three on-treatment deaths were considered unlikely to be due to toxicity. The schedule of IFN-alpha, IL-2 and PVI 5FU has significant activity in advanced renal cell cancer with manageable toxicity. It is of particular interest that this regimen appears to have high activity in fit patients with poor prognostic features.

Adult↗

Neuraminidase inhibitors: progress in the management of influenza.

Influenza is a serious respiratory illness and represents a significant clinical burden. As well as being debilitating, influenza can often cause complications leading to hospitalisation and death. Prophylaxis by vaccination is the preferred method of disease management, but because influenza viruses are constantly changing their antigenic properties, influenza outbreaks occur regularly as epidemics. Neuraminidase inhibitors are a new class of anti-influenza drugs designed to block influenza virus replication. Two neuraminidase inhibitors, zanamivir and oseltamivir, have been licensed for clinical use in the treatment of influenza. Both drugs significantly reduce the severity and duration of the illness when treatment is started within two days of the onset of symptoms. However, while zanamivir and oseltamivir have apparently similar efficacy, they differ in their modes of delivery and tolerability. Zanamivir is delivered direct to the lungs by inhalation and is well tolerated. Oseltamivir is taken in the form of a pill but has the side-effect of producing nausea and vomiting in some patients. In the absence of a demonstrable difference in efficacy, uptake of the two drugs will depend on evaluation of the relative merits of mode of delivery and tolerability.

Acetamides↗

An outbreak of measles in a rural Queensland town in 1997; an opportunity to assess vaccine effectiveness.

This report describes a measles outbreak in a rural town in south-east Queensland and presents the results of a vaccine effectiveness (VE) study performed during this outbreak. It is important to assess the effectiveness of a vaccine in an outbreak to determine if the outbreak is due to failure of the vaccine or failure to vaccinate. There were 44 cases of measles amongst local residents, which represents a notification rate of 396.7 per 100,000 population. Case investigations identified a group of people who had been exposed to measles at a seminar. The attack rate for the seminar cohort was 18% (11/61). This presented an opportunity to conduct a VE study using data about children aged less than 16 years who attended the seminar. In this cohort of 23 attendees, all 7 children who had not received any measles vaccinations became cases whilst the 6 who were fully vaccinated for their age according to NHMRC guidelines were protected from measles illness. Although there were insufficient fully vaccinated cohort members to reliably estimate VE for this group, the vaccine was 84.6% (95% CI: 15.0-99.7%) effective for those who had received at least one validated dose of vaccine. Despite the sample size limitations, the results support the view that failure to vaccinate rather than vaccine failure contributed to the high infection rate in the seminar cohort.

Adolescent↗

Lymph node sampling in localized neuroblastoma: a Pediatric Oncology Group study.

BACKGROUND/PURPOSE: Lymph node (LN) sampling was required by the Pediatric Oncology Group (POG) staging for neuroblastoma and currently is required as a part of the International Neuroblastoma Staging System (INSS). This retrospective study of planned lymph node sampling in patients with localized neuroblastoma was carried out with the intent of assisting surgeons in carrying out this procedure. The report documents the POG experience where LN, both uninvolved and involved with tumor, were found based on site of primary. METHODS: From 391 patients with localized neuroblastoma of the abdomen, chest, and neck, 238 patients had LN sampling at the primary operation, and these patients constitute the major part of the study. In addition, 89 patients had a carefully documented search for LN, and 64 had neither search nor biopsy. The operative note, pathology report, and surgical study sheet were used in the 238 patients based on the site of the primary tumor to determine which nodal groups or basins underwent biopsy, and in which groups tumor was found. RESULTS: The pattern of drainage, based on the primary site of abdominal tumors, favored an arterial rather than venous pathway. Primary tumors and metastatic LN were more numerous on the left side. The abdominal drainage followed three pathways: (1) infrarenal tumors from the left and midline were associated with paraaortic LN; (2) right infrarenal tumors were associated with LN in the paracaval basin; (3) with suprarenal primaries and with both adrenals, the superior mesenteric-portal-celiac basins were most productive for nodal sampling. Tumor was found most frequently in the left adrenal-renal basin and in the paraaortic basin. The actual number of LN sampled in a single case varied from 1 to 19 LN, with a mean number of LN based on stage and primary from one to seven LN. The tumor spread in LN was consistent with a "watershed" course, but this was not statistically significant. Patients for whom LN were sought had a better outcome, contrasting with the patients in whom LN were not sought or in whom nodal sampling was not possible. CONCLUSIONS: The experience in this study is consistent with previous descriptions of the lymphatic drainage of the retroperitoneal area. Delineation of the various basins as they relate to the site of the primary tumor should assist the surgeon in lymph node sampling. The role of LN involvement still remains unclear in the light of current studies of biological factors and histopathology as determinants of "risk groups." It is hoped that this study will enable ongoing and future studies to clarify this problem. The adult experience with breast cancer and with melanoma has indicated a continued importance of anatomic factors (including LN status) along with biological factors.

Abdominal Neoplasms↗

Endoscopic surgery and telemedicine in microgravity: developing contingency procedures for exploratory class spaceflight.

OBJECTIVES: The risk of a urinary calculus during an extended duration mission into the reduced gravity environment of space is significant. For medical operations to develop a comprehensive strategy for the spaceflight stone risk, both preventive countermeasures and contingency management (CM) plans must be included. METHODS: A feasibility study was conducted to demonstrate the potential CM technique of endoscopic ureteral stenting with ultrasound guidance for the possible in-flight urinary calculus contingency. The procedure employed the International Space Station/Human Research Facility ultrasound unit for guide wire and stent localization, a flexible cystoscope for visual guidance, and banded, biocompatible soft ureteral stents to successfully stent porcine ureters bilaterally in zero gravity (0g). RESULTS: The study demonstrated that downlinked endoscopic surgical and ultrasound images obtained in 0g are comparable in quality to 1g images, and therefore are useful for diagnostic clinical utility via telemedicine transmission. CONCLUSIONS: In order to be successful, surgical procedures in 0g require excellent positional stability of the operating surgeon, assistant, and patient, relative to one another. The technological development of medical procedures for long-duration spaceflight contingencies may lead to improved terrestrial patient care methodology and subsequently reduced morbidity.

Endoscopy↗

Modified Campbell diagram to assess respiratory muscle action in speech.

Ten normal and four moderate to severe stutterers participated in the study. Pleural (Ppl) and abdominal (Pab) pressure was studied using oesophageal and gastric balloon catheter systems and VL (VL) was studied using magnetometry. The classical Campbell diagram was modified by plotting Pab versus VL. In a preliminary study we determined whether a surrogate curve could be substituted for the true curve in the Campbell diagram. We obtained true relaxation curves in six subjects. We obtained surrogate chest wall relaxation curves by joining the Pab value at functional residual capacity (FRC) to a point on the dynamic expiratory Pab, VL curve where Pab had decreased to half its maximum inspiratory excursion. In order to obtain the mirror image of the elastic recoil curve of the lung subjects breathed slowly from FRC to total lung capacity. Dynamic Pab, VL and Ppl, VL measurements during quiet breathing and speech were superimposed on static lung and chest wall curves. The simultaneous plot of Ppl and Pab provided a continuous measure of transdiaphragmatic pressure as a function of VL. We inferred non-diaphragmatic muscle recruitment vis-à-vis the diaphragm by the relationship of Pab to Ppl and Pab to the relaxation curve. We compared dynamic Ppl during phonation with that during breath-holding with the glottis open at the same VL, as an estimate of subglottic pressure (Psg). Analysis of variance testing showed that the true, surrogate and predicted relaxation slopes were not significantly different. The strategies that stutterers used to speak were either higher or lower VL than normal subjects and they had a different pattern of respiratory muscle recruitment. Stutterers were unable to achieve the appropriate degree of recruitment to develop and maintain a normal Psg for conversational speech and this contributed to dysfluency. We conclude that the quiet breathing loops can provide a reasonable approximation to the relaxation curve in normal healthy subjects and that modifications to the Campbell diagram provide useful means of measuring Psg and assessing respiratory muscle recruitment patterns.

Adolescent↗

Intensive case management in Australia: a randomized controlled trial.

This study compared intensive case management (ICM) with standard clinical case management in a well-resourced community mental health service in Australia. A total of 73 severely disabled clients of an existing clinical service were randomly allocated to either ICM (caseload 10 clients per clinician) or standard case management (caseload up to 30 clients per clinician) and followed up for 12 months. A greater proportion of clients receiving ICM showed improved social functioning, these clients had fewer psychiatric hospital admissions involving police, and were more likely to engage and remain in treatment compared to those who received standard case management. Clients receiving ICM did not show a reduction in hospitalization duration or total number of episodes. It is suggested that future studies of ICM should focus on which aspects of treatment produce positive outcomes, how they can be applied to routine clinical settings, and over what period of time outcomes are sustained.

Adolescent↗

A prospective analysis of the use of octylcyanoacrylate tissue adhesive for wound closure in pediatric neurosurgery.

OBJECTIVE: Cyanoacrylate monomers have been developed for use as skin adhesives. Previous studies have demonstrated that using this skin adhesive for the closure of traumatic lacerations results in excellent cosmesis, decreased procedure-related pain and timesavings. SURGICAL TECHNIQUE: Octylcyanoacrylate skin adhesive is applied after the placement of deep fascial sutures with close approximation of the skin edges. The adhesive is applied in liquid form and polymerizes rapidly to solid form. Multiple layers are applied forming a hard impenetrable barrier. RESULTS: This technique was prospectively evaluated in the closure of 102 elective neurosurgical operations with 142 incisions: ventriculoperitoneal shunt insertion/revision (53%) and craniotomy for tumors (10%) were the commonest procedures. There were a total of 83 scalp, 36 abdominal, 8 neck, 6 chest and 6 lumbar incisions. The mean incision length was 5.1 cm (range 0.25-50 cm). Fifty-nine percent of the wounds had previous areas of operative incisions. Complications included 1 poor cosmetic result and 4 cerebrospinal fluid (CSF) leaks. Of the 4 patients with CSF leaks, 2 required operative wound revision, and 1 required ventriculoperitoneal shunting for hydrocephalus. CONCLUSION: Cyanoacrylate skin adhesive is a viable means of obtaining cosmetic wound closure. Its use requires attention to proper skin approximation and hemostasis. In our experience, propensity for CSF leakage especially in reoperative procedures is a relative contraindication.

Adolescent↗

Contribution of the MHC region to the familial risk of coeliac disease.

Susceptibility to coeliac disease is genetically determined by possession of specific HLA-DQ alleles, acting in concert with one or more non-HLA linked genes. The pattern of risk seen in sibs and twins in coeliac disease is most parsimonious with a multiplicative model for the interaction between the two classes of genes. Based on a sib recurrence risk for coeliac disease of 10% and a population prevalence of 0.0033, the sib relative risk is 30. To evaluate the contribution of the MHC region to the familial risk of coeliac disease, we have examined haplotype sharing probabilities across this region in 55 coeliac disease families. Based on these probabilities the sib relative risk of coeliac disease associated with the MHC region is 3.7. Combining these results with published data on allele sharing at HLA, the estimated sib relative risk associated with the MHC region is 3.3. Therefore, the MHC genes contribute no more than 40% of the sib familial risk of coeliac disease and the non-HLA linked gene (or genes) are likely to be the stronger determinant of coeliac disease susceptibility.

Celiac Disease↗

Benefit of switching from a protease inhibitor (PI) to nevirapine in PI-experienced patients suffering acquired HIV-related lipodystrophy syndrome (AHL): interim analysis at 3 months of follow-up.

This multicentre, randomized, open-label, prospective trial is evaluating the effects of switching treatment from a protease inhibitor (PI)-containing regimen to one containing the non-nucleoside reverse transcriptase (RT) inhibitor nevirapine in human immunodeficiency virus (HIV)-infected patients with durable viral suppression but suffering from lipodystrophy. Objectives of this ongoing study are to evaluate the effects of this switch on changes in body shape and metabolic abnormalities associated with acquired HIV-related lipodystrophy syndrome (AHL), as well as on maintenance of viral suppression and immunological and psychological effects. Preliminary data involving 57 patients with 3 months of follow-up show an initial improvement of AHL in two regions, the face and arms. There is also a tendency toward improved cholesterol and triglyceride levels and improved quality of life among patients receiving the nevirapine-containing regimen. Maintenance of viral suppression was equivalent in both treatment groups. Additional data with longer follow-up are needed to confirm these results.

Adult↗