Search PubMed⌕ Search

Biomedical subjects

N Powell

Publications and source records attributed to N Powell.

At least 37 records · Page 2Linked to original sources
PubMed1993

Ondansetron versus ondansetron, dexamethasone, and chlorpromazine in the prevention of nausea and vomiting associated with multiple-day cisplatin chemotherapy.

PURPOSE: This study is designed to evaluate the effectiveness of ondansetron alone (OND) or in combination with 2 days of dexamethasone and 5 days of chlorpromazine (ODC) in the prevention of emetic episodes in patients receiving multiple-day cisplatin. PATIENTS AND METHODS: Forty-four patients receiving 20 or 40 mg/m2 of cisplatin daily for 4 to 5 days plus etoposide (VP-16) alone or in combination with bleomycin or ifosfamide were randomized to receive three doses of OND (0.15 mg/kg 30 minutes before and 4 and 8 hours after cisplatin) versus the identical OND regimen plus dexamethasone 8 mg before cisplatin and 4 mg 4 and 8 hours later on days 1 and 2, plus chlorpromazine 50 mg every 4 hours for four doses per day. Patients were chemotherapy-naive, had a Karnofsky performance status > or = 60, and were not receiving nonstudy antiemetics. RESULTS: Nineteen of 22 patients (86%) on ODC had fewer than three emetic episodes throughout the study period, compared with 10 of 22 (46%) on OND (P = .009), and 55% of patients on ODC had no emetic episodes, compared with 32% on OND (P = .22). The ODC arm had fewer treatment failures (5%) than the OND arm (32%). The mean nausea ratings per visual analog scale were 15.0 for OND and 5.5 for ODC (P = .046). Headache was less frequent with ODC versus OND (14% and 41%, respectively, P = .09). CONCLUSION: ODC was superior to OND with respect to therapeutic efficacy and decreased headaches. Both OND and ODC were more effective on days 1 and 2, rather than days 4 and 5, suggesting tachyphylaxis, anticipatory nausea, or delayed nausea from the first few days of cisplatin combination chemotherapy.

Chlorpromazine↗
PubMed1992

Chromosomal genotypes (evolutionary lines) of Salmonella berta.

The copy number and location of the insertion sequence IS200, a mobile DNA element, was established across a collection of Salmonella berta. All strains contained one common site, assumed to be present in the evolutionary ancestor of this serovar. With one exception, all strains, including recent outbreak isolates from the UK and sporadic isolates of world-wide distribution, were representatives of a single genotypic clone which carried three common IS200 insertion sites. This clone has acquired diverse combinations of plasmids, reflecting its actual or recent distribution and host. A single isolate, belonging to a second, minor genotypic clone was characterised by two IS200 insertion sites.

Animals↗
PubMed1992

The insertion sequence IS200 fingerprints chromosomal genotypes and epidemiological relationships in Salmonella heidelberg.

In Salmonella heidelberg the copy number of the Salmonella-specific insertion element IS200 was found to vary from four to six. All strains tested contained at least one common insertion site which was serovar specific, and most strains contained three common sites. Concurrent analysis of plasmids indicated that all insertion sequence copies were chromosomally located, and also supported the equivalence of an IS200 fingerprint and clonality. Seven intra-serovar clonal lines were thereby identified. One of these was associated with human infections, including septicaemias. Another was associated with chicken as a host: all these strains also carried a unique plasmid of 23 MDa, which was typed as a member of the IncX group. The chromosomal fingerprint of a third clone showed it to be a descendant of the chicken line marked by a single IS200 transposition. One or two representatives of four other clonal lines were identified. These lines of S. heidelberg could be related by divergent evolution, and the most recent relatives conformed to a continuous branching process model of IS200 transposition. This insertion sequence provided a highly discriminatory molecular marker of the S. heidelberg chromosome, and two of the seven clonal lines so identified were associated with distinct clinical/epidemiological contexts.

Animals↗
PubMed1991

Attenuating mutations in the E2 glycoprotein gene of Venezuelan equine encephalitis virus: construction of single and multiple mutants in a full-length cDNA clone.

Attenuated mutants of Venezuelan equine encephalitis virus (VEE) were isolated by selection for rapid penetration of cultured cells (R. E. Johnston and J. F. Smith, 1988, Virology 162, 437-443). Sequence analysis of these mutants identified candidate attenuating mutations at four loci in the VEE E2 glycoprotein gene: a double mutation at E2 codons 3 and 4, and single substitutions at E2 76, 120, and 209. Each candidate mutation was reproduced in an isogenic recombinant VEE strain using site-directed mutagenesis of a full-length cDNA clone of VEE. Characterization of these molecularly cloned mutant viruses showed that mutation at each of the four loci in the E2 gene was sufficient to confer both the accelerated penetration and attenuation phenotypes. Inoculation of the molecularly cloned viruses into rodent models that differ in their response to VEE suggested that individual mutations affected different aspects of VEE pathogenesis. Full-length clones containing multiple mutations were produced by combining independently attenuating mutations. Molecularly cloned viruses carrying two or three mutations were more attenuated in sensitive animal models than viruses which contained any single mutation alone. However, these highly attenuated strains still retained the ability to induce an immune response sufficient to protect against a high dose challenge with virulent VEE. These results indicate that production of a molecularly cloned live virus vaccine for VEE is feasible.

Animals↗
PubMed1991

Efficacy of a Rift Valley fever virus vaccine against an aerosol infection in rats.

The formalin-inactivated Rift Valley fever virus (RVFV) vaccine, TSI-GSD-200, was administered subcutaneously to highly susceptible adult Wistar-Furth rats (LD50-1 p.f.u., ZH501 strain). Vaccine was administered on days 0, 7 and 28, the same time course used for at-risk personnel. Six months postimmunization, when the serum plaque-reduction neutralization titre (PRNT)80 had declined to low or undetectable levels, rats were challenged with 4.4 log10 p.f.u. of the virulent ZH501 strain in a nose-only dynamic aerosol apparatus. Ninety-seven per cent (33/34) of the non-vaccinated control rats died. In contrast, only 32% (33/105) of the vaccinated animals died. In vaccinated rats that succumbed, there was a doubling of the mean time to death and the cause of death shifted from hepatitis to encephalitis. Rats with a PRNT80 of greater than or equal to 1:40 were protected from clinical disease and histological evidence of hepatic or encephalitic lesions. While the precise mechanisms of immunity against aerosol challenge remain unresolved, here the serum PRNT titre correlated with protection.

Aerosols↗
PubMed1990

Mediastinal lipoblastoma of infancy.

We report the case of a rapidly expanding mediastinal and chest wall lipoblastoma in an 11-month old infant. Clinical presentation was respiratory distress and chest radiographs revealed a large soft tissue mass in the anterior mediastinum without specific features. CT scanning demonstrated a mass of principally fat attenuation, with enhancing hyperdense soft tissue whorls, which had a compressive effect on normal intrathoracic structures. At surgery the tumour was removed without complication and histology demonstrated an encapsulated, well differentiated lipoblastoma.

Dyspnea↗
PubMed1990

Ultrasound and neonatal hip screening. A prospective study of 'high risk' babies.

We describe a simple, quick ultrasound screening test for CDH, and its use in a prospective study of babies with a 'high risk' factor, over one year from January 1987. From a birth population of 3,879, 812 hip scans were performed on 406 babies and 98 babies were abnormal. So far, there have been no late cases of CDH. Family history, breech malposition, and postural foot deformities were confirmed to be important risk factors, but babies with a simple click were equally at risk. Our early results indicate that a large proportion of the potential late cases are contained within our extended high-risk group.

Hip Dislocation, Congenital↗
PubMed1989

Precipitation of obstructive sleep apnea during pregnancy.

A case of severe obstructive sleep apnea developing during pregnancy is reported. A 27-year-old primigravida was well until the sixth month of pregnancy, when she developed loud snoring and excessive daytime sleepiness. Polysomnography was performed at 36 weeks' gestation and revealed severe obstructive sleep apnea. The patient was treated successfully during pregnancy with nasal continuous positive airway pressure, but continued to suffer from moderate obstructive sleep apnea after delivery. This case suggests that sleep apnea may be either precipitated or exacerbated during pregnancy.

Adult↗
PubMed1988

Inflammatory joint disease: a comparison of liposome scanning, bone scanning, and radiography.

Patients with rheumatoid arthritis, psoriatic arthritis, and osteoarthritis were assessed by clinical evaluation, radiography, and joint scintigraphy using technetium labelled methylene diphosphonate (MDP) and technetium labelled liposomes. Although both scanning techniques were more sensitive than radiographs in detecting joint disease, the liposomes scans were positive only in clinically active inflammatory disease. In patients with rheumatoid arthritis liposome scintigraphy was also able to discriminate between different grades of joint tenderness. In inactive inflammatory polyarthropathies, although the MDP bone scans continued to show increased activity, the liposome scans did not and were therefore a more accurate reflection of the clinical state. The increased uptake in the liposome scans may be due to incorporation of the liposomes into the phagocytic cells of the synovium. This scan may, therefore, by reflecting the activity of cells involved in the disease process, provide a useful way of assessing disease activity and progression.

Arthritis↗
PubMed1988

Nocturnal asthma: snoring, small pharynx and nasal CPAP.

We studied two populations of patients who snored and had frequent nocturnal asthma attacks: ten overweight men presenting with typical obstructive sleep apnoea syndrome, and a group of five adolescents with regular snoring and an increase in negative inspiratory oesophageal pressure during stage II non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. All subjects presented cranio-mandibular abnormalities at cephalometric evaluation, with a narrow space behind the base of the tongue. Both populations were treated with nasal continuous positive airway pressure (CPAP) during sleep. Snoring and partial or complete airway obstruction were eliminated, as were the nocturnal asthma attacks. Two adolescents treated with upper airway surgery after nasal CPAP showed no nocturnal asthma at short-term follow-up. Nasal CPAP had no effect on daytime asthma. One hypothesis is that a subgroup of asthmatic patients with small pharynxes may have enhanced vagal stimulation during sleep compared with other asthmatic patients. This enhancement would be related to the repetitive Müller manoeuvres noted with airway obstruction during sleep. Combined with the local effects of snoring, this extra vagal stimulation would be a precipitating factor in nocturnal asthma attacks.

Adolescent↗
PubMed1987

Current surgical concepts for treating obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome is a relatively common disorder with potentially serious psychologic and physiologic consequences. A comprehensive method of evaluation is described. Presurgical tests are mandatory in order to logically direct surgical treatment. Current surgical treatment and new techniques are discussed.

Electrodiagnosis↗
PubMed1986

Small upper airway in near-miss sudden infant death syndrome infants and their families.

6 infants (index cases) from five different families had a near-miss sudden infant death syndrome event between 3 and 12 weeks of age and had polygraphically documented apnoeas during sleep. 4 of their siblings had died of SIDS. The index cases, their 4 living siblings, 10 parents, and 8 grandparents underwent respiratory studies during sleep. All the adults and 3 index cases had cephalometric X-rays. 2 index cases underwent volume computerised tomographic scans when awake and during sleep. Index cases had mixed and obstructive sleep apnoea. Several family members had obstructive sleep apnoea; cephalometric X-rays also showed small upper airways, particularly behind the base of the tongue. A small posterior airway at the level of the tongue may be a familial risk factor for apnoea of infancy.

Adult↗
PubMed1985

Palatopharyngoplasty failure, cephalometric roentgenograms, and obstructive sleep apnea.

Nine patients with obstructive sleep apnea who underwent unsuccessful palatopharyngoplasty (PPP) as documented by polygraphic monitoring had abnormal cephalometric roentgenogram measurements. Findings indicated a small posterior airway space and inferiorly placed hyoid bone. Cephalometry performed with appropriate techniques to investigate soft tissue location should be obtained systematically in obstructive sleep apneic patients before any surgery is performed. The roentgenogram finding is a helpful guide in deciding whether PPP alone or PPP in combination with other surgical procedures would be more efficacious.

Adult↗
PubMed1985

Sleep apnea in normal subjects following mandibular osteotomy with retrusion.

Two women, 43 and 46 years old, weighing respectively 51 kg and 49 kg, underwent mandibular osteotomy with retrusion, after which they began to snore heavily at night. The initial events were central; obstructive apneic and hypopneic events, documented by polysomnography, developed over time. When patient 2 was on her back, she frequently had central apneas (identified by esophageal pressure monitoring) preceded by increasing swings in pressure, indicative of increased airway resistance without oxygen desaturation.

Adult↗