PubMed Health⌕ Search

Biomedical subjects

L Stewart

Publications and source records attributed to L Stewart.

At least 19 recordsLinked to original sources
PubMed1992

Event related potentials, reaction time, and cognitive performance in idiopathic Parkinson's disease.

Sixteen non-demented patients with idiopathic Parkinson's disease (PD) with varying degrees of cognitive impairment and sixteen age-, sex- and education-matched normal controls were examined with (1) an auditory oddball paradigm requiring counting or a motor response in separate determinations, (2) a reaction time task with movement time component and (3) a detailed clinical and neuropsychological test battery. Patients were impaired on a number of neuropsychological tests. They also showed an increased P2 and N2 latency, but no significant increase in P3 latency. Their response initiation times and reaction times during the oddball experiment were not different from controls, whereas movement time was significantly increased. Increased peak latencies, particularly for N2, were moderately associated with Parkinsonian motor impairment in patients and with the Benton Multiple Choice Visual Retention Test in patients and controls. Movement time was associated with P3 latency only in controls and in both groups with the Benton Multiple Choice Visual Retention Test. The observed pattern of results suggests that in non-demented PD patients ERP peak latencies, visuo-spatial task performance and Parkinsonian motor impairment share a significant degree of variance. While impairments in neuropsychological tests and delay in the earlier peaks P2 and N2 do not appear to be sensitive to medication with L-DOPA, normal P3 latencies might indicate good pharmacological symptom control in the absence of dementia.

Aged↗
PubMed1992

Meta-analysis of the role of platinum compounds in advanced ovarian carcinoma. The Advanced Ovarian Cancer Trialists Group.

This paper presents a systematic overview or meta-analysis of 54 randomized clinical trials testing a variety of chemotherapeutic approaches in advanced ovarian carcinoma. Prolonged follow-up data are available for most patients and individual patient data were made available for all patients; analysis was made on the basis of "intention to treat." Our report concentrates on two comparisons: (1) platinum alone versus platinum in combination, which appears to show a long-term survival advantage for the combination (however, the platinum dose in the single-agent arm was relatively low); and (2) carboplatin versus cisplatin, which shows no obvious survival differences. It is striking that no single study to date has been large enough to detect the modest survival differences expected from current therapy. Consequently, a series of international studies have been initiated. The International Collaborative Ovarian Neoplasm (ICON) group will examine the role of adjuvant chemotherapy in early ovarian cancer (ICON 1) and will compare carboplatin with cisplatin, doxorubicin, and cyclophosphamide in more advanced disease (ICON 2).

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Dementia in idiopathic Parkinson's disease: prevalence and relationship with symptoms and signs of parkinsonism.

A whole population cohort of 157 patients with idiopathic Parkinsonism, most of whom had previously been clinically examined by Mutch (1986a), were assessed to determine prevalence figures for dementia and examine the relationship between dementia, cognitive impairment and Parkinsonian signs. Dementia according to DSM-III-R criteria was diagnosed in 23.3% of all patients (95% confidence interval: 17.1 to 32.4%). Dementia and cognitive impairment were associated with overall measures of Parkinsonian impairment and rigidity, but not tremor, even after controlling for age, sex and education.

Adult↗
PubMed1991

Granulocyte colony-stimulating factor enhances pulmonary host defenses in normal and ethanol-treated rats.

Ethanol suppresses functions of the polymorphonuclear leukocyte (PMNL), seriously compromising normal host defenses against pneumonia. Because granulocyte colony-stimulating factor (G-CSF) augments the number and function of PMNL, the effect of G-CSF on the antibacterial defenses of the lung in normal and acutely intoxicated rats was studied. Animals received G-CSF or vehicle twice a day for 2 days, then ethanol or saline, followed by challenge with Klebsiella pneumoniae. K. pneumoniae elicited an intrapulmonary influx of PMNL in control rats that was markedly suppressed by prior ethanol administration. G-CSF augmented the recruitment of PMNL into the lungs of control rats and significantly attenuated the adverse effects of ethanol on PMNL entry into the lung. G-CSF enhanced intrapulmonary bactericidal activity against this pathogen in normal and ethanol-treated rats. All intoxicated rats pretreated with the vehicle died, while greater than 90% of rats pretreated with G-CSF survived. These findings suggest a potential role for G-CSF in mitigating the adverse effects of ethanol on PMNL delivery and pulmonary host defenses.

Alcoholic Intoxication↗
PubMed1991

Specific syphilis serological tests may become negative in HIV infection.

The diagnosis of syphilis is frequently dependent upon the results of serological tests, but the reliability of syphilis serology in patients with HIV-1 infection has been questioned. We examined specific antibody to Treponema pallidum (TP) using the TP haemagglutination (TPHA) and fluorescent treponemal antibody-absorption (FTA-ABS) tests in AIDS patients and HIV-antibody-negative controls with a history of syphilis. Tests were carried out on two sera separated by an interval of at least 3 years from each patient. Twelve out of 29 AIDS patients compared with four out of 29 controls showed significant falls in titres of specific antibody as measured by the TPHA, FTA-ABS, or by both the TPHA and FTA-ABS (P = 0.02). Furthermore, in three out of 29 (10%) of the AIDS patients with past syphilis infections both the TPHA and FTA-ABS became non-reactive. We conclude that negative specific serology does not exclude a past syphilis infection in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1991

trans-acting viral protease is necessary and sufficient for activation of avian leukosis virus reverse transcriptase.

The structural and enzymatic components of retroviral cores are formed by proteolytic cleavage of precursor polypeptides, mediated by the viral protease (PR). We described previously the construction of PR-defective avian leukosis viruses. These mutant viruses are noninfectious, and their major internal components are the uncleaved gag and gag-pol polyproteins (Pr76gag and Pr180gag-pol). The reverse transcriptase (RT) activity associated with the PR-defective virions is approximately 500-fold reduced relative to that of wild-type virions, suggesting that specific cleavages activate RT activity. To gain a better understanding of the role that PR plays in the processing and activation of RT, we performed complementation experiments wherein wild-type or PR mutant gag precursors were separately coexpressed with frame-corrected wild-type or PR mutant gag-pol precursors. The results demonstrate that, as in other retrovirus systems, gag-pol precursors can be assembled into virions only when they are rescued by a gag precursor. If the gag precursor is wild type, then the rescued Pr180gag-pol is completely and properly matured, irrespective of whether its embedded PR domain is wild type or mutant. In both cases, the virions produced are fully and equally infectious. This indicates that an active-site mutation in the PR domain of the gag-pol precursor has no effect on avian leukosis virus infectivity when particles are assembled from wild-type gag precursors. In contrast, if the gag precursor has an active-site mutation in PR or is deleted for PR, then the virions are noninfectious and the gag and gag-pol precursors remain unprocessed, even if the embedded PR domain of Pr180gag-pol is wild type. Thus, in this system, virion-associated Pr180gag-pol displays no detectable cis- or trans-acting PR activity. As assayed with an exogenous template, virions with processed gag-pol polyprotein display high levels of RT activity while those with unprocessed Pr180gag-pol display greatly reduced RT activity. These results demonstrate that during virion assembly, the PR supplied by a gag precursor is both necessary and sufficient for trans-activation of RT through proteolytic maturation of copackaged gag-pol polyprotein.

Amino Acid Sequence↗
PubMed1990

Enzyme-linked immunosorbent assays for detecting antibody to Rickettsia australis in sera of various animal species.

New endemic areas of spotted fever-like rickettsial disease have been found in south-eastern Australia (Gippsland, Victoria and Flinders Island, Tasmania). The rickettsia responsible is currently unknown although it may be Rickettsia australis. To investigate serological evidence of rickettsial exposure in various wild animal species, a competitive ELISA was developed which detected antibodies to R. australis. It was based on inhibition of an indirect ELISA detecting antibody to R. australis in guinea pig sera. Pre- and post-infection sera from 2 dogs, 2 rabbits, 5 mice and 6 rats, experimentally infected with R. australis, were tested by competitive ELISA. The results showed that all pre-infection sera were negative and all post-infection sera positive for antibody to R. australis. To test the utility of the competitive ELISA for detecting natural rickettsial infection in non-laboratory animals, 51 dog sera, negative for rickettsial antibody by immunofluorescence (IF) and 20 IF positive dog sera (collected from various locations on the east coast of Australia) were tested. Compared to the IF test the competitive ELISA was 90% sensitive and 96% specific. This new test has potential for detecting antibody to R. australis in the sera of different wild animal species.

Animals↗
PubMed1990

Parkinson's disease in Aberdeen: survival after 3.5 years.

The increasing age of the general population and of patients suffering from Parkinson's disease suggests that a reappraisal of mortality rates and factors related to increased mortality should be carried out. A 3.5 year follow-up of a whole population sample of 267 patients and 233 controls matched by age, sex and general practitioner, yielded a relative mortality rate of 2.35 (99%-confidence interval: 1.60-3.43). Factors predicting death within the follow-up period were: cognitive impairment, old age, late age of onset, long history of smoking, lower blood pressure, and a variety of signs, symptoms and sequelae of Parkinson's disease associated with decreased mobility. However, age less than 70 years, age of onset before 66 years, absence of kyphosis or normal Webster posture score, mild impairment on the Hoehn & Yahr scale (1-2), or no impairment in a 10-question mental status questionnaire (9-10), were not associated with an increased risk of death.

Aged↗
PubMed1990

Properties of avian retrovirus particles defective in viral protease.

The structural and enzymatic components of retroviral cores are formed by proteolytic cleavage of precursor polypeptides, mediated by the viral protease (PR). We constructed an active-site mutation, D37I, in the PR of avian leukosis virus. The D37I mutation was introduced into an infectious DNA clone, and quail cell lines expressing the mutant virus were established. These cell lines produce normal amounts of virus particles, the major internal protein components of which are the uncleaved gag and gag-pol precursors. As in other retroviral systems, the protease-defective virions are noninfectious and retain the "immature" type A morphology as determined by thin-section transmission electron microscopy. The virion cores are stable at nonionic detergent concentrations that completely disrupt wild-type cores. Digestion of mutant virions with exogenous PR in the presence of detergent leads to complete and correct cleavage of the gag precursor but incomplete cleavage of the gag-pol precursor. The protease-defective virions encapsidate normal amounts of genomic RNA and tRNA(Trp) that is properly annealed to the primer-binding site, but some of the genomic RNA remains monomeric. Results from UV cross-linking experiments show that the gag polyprotein of mutant virions interacts with viral RNA and that this interaction occurs through the nucleocapsid (NC) domain. However, within mutant virions the interaction of the NC domain with RNA differs from that of mature NC with RNA in wild-type virions. Reverse transcriptase (RT) activity associated with mutant virions is diminished but still detectable. Digestion of the virions with PR leads to a fivefold increase in activity, but this PR-mediated activation of RT is incomplete. Since in vitro cleavage of the gag-pol precursor is also incomplete, we hypothesize that amino acid sequences N terminal to the reverse transcriptase domain inhibit RT activity.

Animals↗
PubMed1990

Mortality and causes of death in idiopathic Parkinson's disease: results from the Aberdeen whole population study.

Two hundred and forty-nine patients with Parkinson's disease previously examined by Mutch et al 1,2 were followed up three and a half years after the original study. Cognitive impairment, age, some postural signs and symptoms of Parkinson's disease and high scores on the Hoehn and Yahr scale predicted premature death. Patients were more likely to die from respiratory infections than controls. Respiratory diseases as cause of death recorded on the death certificate were not related to kyphosis, posture scores or Hoehn and Yahr scores before death. The hypothesis is advanced that death of respiratory causes might be associated with signs of general autonomic dysregulation.

Aged↗
PubMed1990

Clinical features predicting dementia in idiopathic Parkinson's disease: a follow-up study.

We followed up, after 3 1/2 years, a whole population cohort of 249 patients with Parkinson's disease (PD) 1st examined in 1983 to 1984. Of the survivors, 23.6% qualified for a DSM III-R diagnosis of dementia. In univariate tests, age, certain items of the Webster scale, the Hoehn and Yahr scale, a 10-question mental status questionnaire, and a history of smoking were associated with a diagnosis of dementia 3 1/2 years later. Logistic regression with DSM III-R diagnosis (demented versus nondemented) as the dependent variable, and age and symptom scales for PD as predictor variables, revealed that PD symptoms predicted dementia even after controlling for age. We conclude that dementia is probably more common in PD patients than would be expected in the general population and is associated with the severity of PD symptoms and signs independently of age.

Age Factors↗
PubMed1989

Structure of bovine adrenal dopamine beta-monooxygenase, as deduced from cDNA and protein sequencing: evidence that the membrane-bound form of the enzyme is anchored by an uncleaved signal peptide.

A full-length cDNA for dopamine beta-monooxygenase (D beta M) from bovine adrenal glands has been cloned and sequenced. The soluble and membrane-derived forms of D beta M have also been sequenced from their N-termini. While the observed sequences for the soluble protein correspond to those previously reported [Joh, T.H., & Hwang, O. (1986) Ann. N.Y. Acad. Sci. 493, 343-350], the heavy subunit of membrane-derived enzyme is found to contain a unique N-terminus. Alignment of this N-terminus with that deduced from cDNA cloning indicates identity at 22 (and possibly 26) out of 27 residues. This comparison leads us to conclude that the membranous form of bovine D beta M retains an uncleaved N-terminal signal peptide as the source of membrane anchoring.

Adrenal Glands↗
PubMed1989

Gallstone disease. The clinical manifestations of infectious stones.

Gallstones from 82 patients were examined under a scanning electron microscope for evidence of bacteria, and the findings were compared with the clinical manifestations of the disease. Bacteria were present in 68% of pigment stones and the pigment portions of 80% of composite stones. These gallstones were referred to as infectious stones. No bacteria were found in cholesterol gallstones. Acute cholangitis was diagnosed in 52% of patients with infectious stones and in 18% of patients with noninfectious stones. Over half of the patients with noninfectious stones presented with mild symptoms. Infectious stones were more often associated with a previous common duct exploration, an urgent operation, infected bile, a common duct procedure, and complications. These data show that gallstone disease is more virulent in patients whose gallstones contain bacteria.

Acute Disease↗
PubMed1989

Does idiopathic parkinsonism in Aberdeen follow intrauterine influenza?

A study is presented which fails to replicate a recent report that peak years of birth of patients later developing Parkinson's disease are related to the influenza pandemics of the period 1890-1930. The years of birth of a whole population cohort of 243 patients suffering from Parkinson's disease examined in Aberdeen in 1983 and reexamined in 1986/7 were compared with deaths due to influenza in the City of Aberdeen in the years 1900-1930. Although a significant peak of Parkinson births (compared with the age profile of the Aberdeen population in 1983) occurred in 1902, there appeared to be no systematic relationship between Parkinson births and influenza deaths. In addition, no season of birth effect could be detected in a comparison with 232 matched controls. The presence of peaks of birth years, for whatever aetiological reason, is of significance to epidemiological studies in that prevalence estimates may be influenced by the year of study relative to these mini-cohorts.

Aged↗