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Biomedical subjects

D Armstrong

Publications and source records attributed to D Armstrong.

At least 235 records · Page 13Linked to original sources
PubMed1995

Expression analysis of the ataxin-1 protein in tissues from normal and spinocerebellar ataxia type 1 individuals.

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant neurodegenerative disorder caused by expansion of a CAG trinucleotide repeat which codes for glutamine in the protein ataxin-1. We have investigated the effect of this expansion on ataxin-1 by immunoblot analysis. The wild-type protein is detected in both normal and affected individuals; however, a mutant protein which varies in its migration properties according to the size of the CAG repeat is detected in cultured cells and tissues from SCA1 individuals. The protein has a nuclear localization in all normal and SCA1 brain regions examined but a cytoplasmic localization of ataxin-1 was also observed in cerebellar Purkinje cells. Our data show that in SCA1, the expanded alleles are faithfully translated into proteins of apparently normal stability and distribution.

Animals↗
PubMed1995

Endoscopic features of Helicobacter pylori-related gastritis.

BACKGROUND AND STUDY AIMS: It is still controversial whether certain endoscopic features can be used to diagnose Helicobacter pylori (Hp)-related gastritis. To clarify this issue, we performed two consecutive prospective studies. PATIENTS AND METHODS: In the first study, we tried to identify endoscopic criteria associated with Hp-related gastritis from a total of 66 predefined gastric features on endoscopy. These features were selected by a stepwise logistic regression analysis in 101 patients. The validity of these features gained from this first study was then evaluated in a second study in 86 patients (40 with Hp gastritis, 8 with Hp-unrelated gastritis and 38 with normal gastric mucosa). RESULTS: Three features, namely an abnormal antral surface texture, a mammillated corpus surface, and white antral erosions, were identified in the first study as independent predictors of Hp-related gastritis. However, the sensitivity and specificity of these three criteria, as assessed in the second study, were only 75% and 63% respectively. CONCLUSIONS: We conclude that it is not possible to diagnose Hp-related gastritis on the basis of the endoscopic appearance alone. The diagnosis should be based on other criteria, such as a rapid urease test, or a histological examination of gastric biopsies, or both.

Adult↗
PubMed1995

Selective dendritic alterations in the cortex of Rett syndrome.

Rett syndrome, the commonest condition associated with severe mental retardation in girls, is diagnosed only by its clinical phenotype, because, to date, there is no consistent characteristic alteration in genetic, biochemical, neurotransmitter or morphologic marker. The clinical features at various ages suggest involvement of most parts of the nervous system, however, the brain in Rett syndrome is reduced in weight, without other obvious morphologic alterations. Because of the relative microcephaly, hypotheses regarding failure of development have been suggested. Supporting such hypotheses are the quantitative studies by Jellinger, Seitelberger and Kitt defining a decrease in the amount of melanin in the substantia nigra and by Bauman defining a global decrease in the size of the neurons. In this study the cerebral cortex has been examined using the rapid Golgi technique with the purpose of investigating dendrites of pyramidal neurons in six cortical regions of Rett girls from ages 2.9-35 years. Camera lucida drawings of apical and basal dendrites of two cortical layers and CA1 were prepared. These were submitted to the Sholl analysis. The Sholl analyses were tested for significance using the repeated measures analysis of covariance, with age as a covariate. The studies demonstrate that from our samples there is no evidence that the pyramidal neurons in Rett syndrome degenerate progressively with increasing age but that the basal dendrites of layers three and five pyramidal neurons in the motor and frontal cortex, the apical dendrites of layer five of the motor cortex, and the basal dendrites of layer four of the subiculum are significantly shorter than in non-Rett brains.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Motivational styles in English and mathematics among children identified as having special educational needs.

This study is concerned with the identification, development and prevalence of three different motivational styles: learned helplessness, self-worth motivation and mastery orientation in two National Curriculum core subjects: English and mathematics. These three motivational styles are concerned with the ways in which children respond in the face of difficult and challenging educational tasks. Using Craske's (1988) procedures, a total of 437 children in their first year of secondary school (aged 11-12) were categorised into one of the three motivational styles. Children with special educational needs were identified using a battery of cognitive ability tests (Thorndike, Hagen & France, 1986). This study compares the prevalence of each motivational style in English and mathematics in children of different abilities and presents empirical support for the view that learned helplessness and self-worth motivation are more prevalent among children identified as having special educational needs. Further analyses indicate that: overall, learned helplessness and self-worth motivation are more prevalent in English than mathematics; learned helplessness is more prevalent among girls and self-worth motivation among boys in mathematics. Implications for teachers in developing teaching strategies which foster mastery orientation in their children are discussed.

Adolescent↗
PubMed1995

Aerosol and parenteral pneumocandins are effective in a rat model of pulmonary aspergillosis.

The pneumocandins are semisynthetic analogs of echinocandin-like compounds that have shown efficacy in animal models of systemic candidiasis, disseminated aspergillosis, and pneumocystis pneumonia. However, the most common form of Aspergillus infection in susceptible patients is pulmonary aspergillosis, which was not directly tested in the mouse models used in the past. We have evaluated three pneumocandins, L-693,989, L-731,373, and L-733,560, in a rat model of pulmonary aspergillosis. Male Sprague-Dawley rats were treated for 2 weeks with cortisone and tetracycline and fed a low-protein diet before being inoculated via the trachea with 10(6) conidia of Aspergillus fumigatus H11-20. In the absence of drug treatment, the animals developed a progressive, rapidly fatal bronchopneumonia. All three pneumocandins at doses of 5 mg/kg (intraperitoneally [i.p.] every 12 h [q12h]) were effective in delaying mortality in this model. Survival at day 7 postinfection was 20% among controls (n = 10 for all groups), while it was 60, 80, and 90% in groups that were treated with L-693,989, L-731,373, and L-733,560, respectively. In another trial, survival at day 7 postinfection was 25% among controls (n = 8 for all groups); it was 87.5% in a group treated with amphotericin B (0.5 mg/kg i.p. q12h) and was 100% in a group treated with L-733,560 (0.625 mg/kg i.p. q12h). In a separate trial, aerosol L-693,989 administered 2 h before infection (5 mg/kg) delayed mortality. Eight of the 10 animals treated with aerosol L-693,989 survived for 7 days, whereas only 2 of 10 control animals survived. We conclude that the pneumocandins we tested were highly effective in an animal model of pulmonary aspergillosis.

Aerosols↗
PubMed1995

Tuberculosis in the AIDS era.

A resurgence of tuberculosis has occurred in recent years in the United States and abroad. Deteriorating public health services, increasing numbers of immigrants from countries of endemicity, and coinfection with the human immunodeficiency virus (HIV) have contributed to the rise in the number of cases diagnosed in the United States. Outbreaks of resistant tuberculosis, which responds poorly to therapy, have occurred in hospitals and other settings, affecting patients and health care workers. This review covers the pathogenesis, epidemiology, clinical presentation, laboratory diagnosis, and treatment of Mycobacterium tuberculosis infection and disease. In addition, public health and hospital infection control strategies are detailed. Newer approaches to epidemiologic investigation, including use of restriction fragment length polymorphism analysis, are discussed. Detailed consideration of the interaction between HIV infection and tuberculosis is given. We also review the latest techniques in laboratory evaluation, including the radiometric culture system, DNA probes, and PCR. Current recommendations for therapy of tuberculosis, including multidrug-resistant tuberculosis, are given. Finally, the special problem of prophylaxis of persons exposed to multidrug-resistant tuberculosis is considered.

AIDS-Related Opportunistic Infections↗
PubMed1995

Effect of Helicobacter pylori status on intragastric pH during treatment with omeprazole.

To test the hypothesis that Helicobacter pylori infection is associated with a decreased intragastric acidity during omeprazole therapy, ambulatory 24 hour dual point gastric pH recordings were performed in 18 H pylori positive and 14 H pylori negative subjects. There was a four to six week washout period between the two pH recordings made in each subject after one week courses of placebo or omeprazole, 20 mg daily. During placebo, median 24 hour pH values were not different in the corpus (H pylori positive = 1.5, negative = 1.4; p = 0.9) or antrum (H pylori positive = 1.3, negative = 1.2; p = 0.1). However, during omeprazole treatment, median 24 hour pH values were higher in H pylori positive subjects, both in the corpus (H pylori positive = 5.5, negative = 4.0; p = 0.001) and antrum (H pylori positive = 5.5, negative = 3.5; p = 0.0004). During placebo treatment, the only difference between the two groups was a higher later nocturnal pH in the antrum in the H pylori positive group. During omeprazole treatment, gastric pH was higher both in the corpus and in the antrum in the H pylori positive group for all periods, except for mealtime in the corpus. These data indicate that omeprazole produces a greater decrease in gastric acidity in subjects with H pylori infection than in those who are H pylori negative. It is not, however, known whether there is a causal relationship between H pylori infection and increased omeprazole efficacy.

Adult↗
PubMed1995

Effect of curing Helicobacter pylori infection on intragastric pH during treatment with omeprazole.

It has been shown that omeprazole treatment produces higher intragastric pH values in Helicobacter pylori positive subjects than in H pylori negative subjects. This study aimed to investigate the effect of curing H pylori on the intragastric pH in both the presence and absence of omeprazole therapy. Twenty four hour intragastric pH recordings were performed before and after a one week course of omeprazole (20 mg once daily) in 18 H pylori positive subjects and were repeated after the infection had been cured. In the absence of omeprazole, the total 24 hour pH values before cure did not differ from those afterwards. During omeprazole treatment the 24 hour pH values were much higher before (median (95% CI) 5.4: 4.3, 6.0), than after cure of infection (3.6: 2.1, 4.4; p < 0.001). The omeprazole induced fall in H+ activity before cure of H pylori did not, however, differ from that afterwards. It is concluded that the apparently greater antisecretory effect of omeprazole during H pylori infection may be a result of the production of acid neutralising compounds by the H pylori. Although a direct interaction between H pylori and omeprazole cannot be excluded, it seems unlikely.

Adult↗
PubMed1995

Encephaloceles of the anterior cranial fossa.

From a total of 114 encephaloceles treated surgically at The Hospital for Sick Children in the 15 years to 1994, the case records of 17 patients with sincipital and 5 patients with basal defects were reviewed retrospectively. The condition was evident at birth in 64% of patients, while the remainder presented with either cerebrospinal fluid (CSF) rhinorrhea, nasal obstruction, or feeding difficulty. Hypertelorism affected 73% of patients. All encephaloceles were repaired transcranially, at a mean age of 2 years, usually by means of an intradural pericranial graft. Five children with gross hypertelorism underwent orbital translocation at the time of encephalocele repair. Of those not corrected, primary and secondary hypertelorism regressed in most instances where the encephalocele was treated before the age of 2 years. There were no deaths. The only case of CSF rhinorrhea occurred in a patient with a basal defect, in whom intradural repair was not possible because of adherence of diencephalic structures to the sac wall. Hypertelorism recurred in 1 patient after orbital translocation, requiring recorrection 2 years later. One patient with untreated secondary hypertelorism failed to regress after the encephalocele was excised at the age of 4 months. Developmental outcome was normal in 59% of children, whilst 18% have mild mental or physical disability, and 23% are severely impaired. A child with a sincipital or basal defect and mild hypertelorism should have the encephalocele treated in early childhood to allow the facial skeleton to remodel with growth. When an encephalocele is accompanied by gross hypertelorism or a facial cleft, one-stage correction can be undertaken safely in early childhood with minimal mortality and acceptable morbidity.

Encephalocele↗
PubMed1995

Cranio-orbito-zygomatic measurements from standard CT scans in unoperated Treacher Collins syndrome patients: comparison with normal controls.

Fourteen reproducible cranio-orbito-zygomatic measurements taken from 26 standard axial computed tomographic (CT) scans of unoperated individuals with symmetric forms of Treacher Collins syndrome (TCS) were compared to age-matched controls. The interorbital measurements of the TCS patients were at the mean when compared to their cohort group (medial and lateral orbital wall separation), while the zygomatic measurements were significantly less than normal confirming the extent of malar hypoplasia. The congenitally deficient lateral aspect of the orbits in TCS patients was confirmed by the greater than normal values measured for globe protrusion and medial orbital wall protrusion in conjunction with the diminished lateral orbital wall lengths, all of which use the lateral orbital rim as a reference point. The abnormal shape of the anterior cranial vault in patients with TCS was documented as a diminished intercoronal distance (width) and decreased cephalic length when compared to normal age-matched controls.

Adolescent↗
PubMed1995

Cognitive determinants of quality of life after onset of cancer.

To investigate cognitive coping styles and how they might relate to perceived quality of life for individuals seriously ill with cancer 41 mostly elderly, male patients with a wide variety of cancers were administered the Illness Effects Questionnaire, a quality of life measure, the COPE Questionnaire, which samples different coping strategies, and questions regarding beliefs about illness behaviors, expectations about cancer's effects, comparisons of the participants' lives with those of others, feelings since having cancer, and motivation to resist lifestyle disruptions. Six of the belief factors and two of the coping strategies were related to perceived quality of life. If the effects of cancer were less than expected, quality of life was better; with an expectation of a negative effect from the disease, lowered quality of life was perceived. Two coping strategies were related to quality of life, suppression of competing activities and using religious practices. Other relationships were also discussed.

Adaptation, Psychological↗
PubMed1995

The origin of nocturnal intragastric pH rises in healthy subjects.

BACKGROUND: Duodenogastric reflux (DGR) can produce transient increases in gastric luminal pH. It has been proposed that intragastric pH-metry is a reliable method for the detection of DGR. Our aim was to test the hypothesis that nocturnal increases in antral pH are due solely to DGR. METHODS: Gastric pH was monitored overnight using two glass pH electrodes, one in the antrum adjacent to the tip of a nasogastric tube and one in the corpus. Scheduled antral aspirations were performed hourly to determine base-line concentrations of total bile acids (TBA; a marker of DGR) and thiocyanate (SCN; a marker of swallowed saliva). Additional, triggered aspirations were performed if antral pH exceeded 3.0 for 1 min or more (PHAP; period of high antral pH). TBA and SCN were considered to be increased if they exceeded the 90th percentile of values determined in scheduled aspirates (TBA, 0.88 mM; SCN, 0.67 mM). RESULTS: In 28 of the 62 samples whose aspiration was triggered by a PHAP the pH was less than 3.0, and the sample was not considered to be representative. In the remaining 34 samples the antral luminal pH and the sample pH were concordant; TBA alone was increased in 6 samples, SCN alone was increased in 6 samples, and TBA and SCN were both increased in another 3 samples. Thus, DGR and swallowed saliva alone or in combination accounted for only 15 (45%) of the PHAP in which adequate gastric samples were obtained. CONCLUSION: Samples of gastric antral contents often do not reflect accurately the acidity of gastric fluid in contact with a luminal antral pH electrode. Nocturnal increases in antral pH, detected by a luminal electrode, are frequently due to mechanisms other than duodenogastric reflux or swallowed saliva. Thus, antral pH-metry is not suitable for monitoring the occurrence of duodenogastric reflux.

Adult↗
PubMed1995

Use of frameless stereotaxy with location of electroencephalographic electrodes on three-dimensional computed tomographic images in epilepsy surgery.

Epileptiform activity corresponding to structural lesions was identified by three-dimensional (3D) imaging using computed tomographic (CT) scan data concurrently with scalp EEG electrodes. The electrodes, placed according to the international 10-20 system, were used to record interictal and ictal epileptogenic foci in eight patients. Electrodes placed where marked or moderate epileptiform activity was detected were replaced with markers detectable on CT. Scans with these markers on the skin were obtained and the data transferred to a 3D imaging system, and correlated with underlying cerebral structures. The reformatted images were used to assess the relation among intracranial lesions, brain surface structures, and epileptogenic zones depicted by the markers. The images help the surgeon plan a craniotomy with enough space for both lesionectomy and resection of the epileptogenic zone. In the central regions where crucial motor functions are located, the markers indicate the central fissure or postcentral gyrus. An intraoperative 3D frameless stereotactic pointing device helps in directing further examination of the epileptogenic zone. This system improves on the precision available through intraoperative electrocorticographic recording in the extratemporal lobes, thus avoiding only approximate excision of lesion and epileptogenic zone and enabling the neurosurgeon to perform epilepsy surgery with greater confidence.

Adolescent↗
PubMed1995

[Functional dyspepsia: approaches to Helicobacter pylori eradication therapy].

At the present, Helicobacter-associated gastritis is not considered to be an important cause of dyspeptic symptoms. Therefore, patients with dyspeptic symptoms and proven Helicobacter-gastritis are diagnosed as having functional dyspepsia, provided that Helicobacter-associated lesions like ulcers or malignancies are absent. It is controversial whether or not to treat a patient with functional dyspepsia with Helicobacter gastritis. Conclusive controlled clinical trials are lacking. If it is assumed in a given patient, that Helicobacter could be responsible for the complaints (an assumption which can never be proven and only suspected when the patient remains asymptomatic during longterm follow-up after cure of the infection) and if the patient has not responded to a standard treatment (antisecretory or prokinetic agents), we recommend Helicobacter therapy. Presently, in spring 1995, the following treatment is, in our view, the best choice during seven (to ten) days: The patient takes 20 mg omeprazol in the morning, 250 mg clarithromycin in the morning and in the evening and 500 mg metronidazole in the morning and in the evening.

Clarithromycin↗
PubMed1995

Investigation of burnout in a sample of British general practitioners.

BACKGROUND: Recent changes in the general practitioner contract have produced increased workload and stress, poorer mental health and reduced job satisfaction. These factors might combine to increase the level of 'burnout' among general practitioners. AIM: This study set out to examine the extent of burnout among general practitioners. METHOD: A questionnaire was sent to all 295 Northamptonshire general practitioners seeking demographic details and including the Maslach burnout inventory. The results for the inventory were compared with the results from a sample of physicians and nurses in North America. RESULTS: There was a significantly higher level of burnout among the Northamptonshire doctors compared with the North American sample. There was virtually no association between age and the level of burnout, although a small negative correlation was found between age and the depersonalization of others subscale. Part-time general practitioners showed lower levels of burnout than full-time general practitioners. CONCLUSION: This study highlights the need to look both at the extent of burnout in young doctors during their training and at those characteristics of part-time general practitioners which might prevent burnout.

Burnout, Professional↗
PubMed1995

Metopic and sagittal synostosis: intracranial volume measurements prior to and after cranio-orbital reshaping in childhood.

This study applied a proven method for obtaining intracranial volume measurements using CT scans to (1) measure the intracranial volume of a consecutive series of children with either metopic or sagittal synostosis prior to any craniofacial procedure, (2) perform a standard cranio-orbital operation in each child, follow them longitudinally, and remeasure their intracranial volume 1 year later, and (3) compare their intracranial volumes with those of an age- and gender-matched cohort and review their cranial growth velocity. The study included 18 children who presented sequentially with untreated isolated nonsyndromic sagittal (n = 8) and metopic (n = 10) synostosis between 1987 and 1990 and who subsequently underwent cranio-orbital reconstruction by the senior author (Posnick) in conjunction with a pediatric neurosurgeon. The primary method of osteotomy and bone-graft fixation varied (i.e., wires, miniplates and microplates and screws). The series included 5 females and 13 males with an average age at the time of operation of 27 months (range 6 to 87 months). The postoperative clinical follow-up ranged from 13 to 47 months at the close of the study. Comparison of our patients' preoperative intracranial volumes with age- and gender-matched volumes available through Lichtenberg showed that 16 of 18 (89 percent) had volumes at or greater than the mean, with 44 percent (7 of 16) exceeding 2 standard deviations above the mean. When comparing our patients' late postoperative volumes with the Lichtenberg normative measurements, 94 percent achieved values at or greater than the mean. All patients achieved increased intracranial volume in association with the surgery performed and the time that lapsed between scan intervals. The majority of our patients (16 of 18) followed an intracranial volume growth curve that closely approximated the norm but with a starting point determined by the preoperative value. Two of 18 followed a growth curve that exceeded the rate of expansion expected for normal children. Our findings suggest that premature closure of either the sagittal or metopic suture does not result in diminished intracranial volume prior to or after the cranio-orbital procedures carried out in childhood. For the majority of the children in our study, both the preoperative intracranial volume and the rate of cranial expansion approximated or surpassed that of children without synostosis. The surgical techniques of skull and upper orbital reshaping with varied forms of osteotomy and graft fixation did not result in a global form of growth restriction. These findings are contrary to standard thinking about the biologic effects of craniosynostosis and raise new questions about our rationale for treatment.

Case-Control Studies↗
PubMed1995

Crouzon and Apert syndromes: intracranial volume measurements before and after cranio-orbital reshaping in childhood.

This study applied a proven method for obtaining intracranial volume (ICV) measurements using computed tomographic scans to document ICVs in children with Crouzon and Apert syndrome before and after cranio-orbital reshaping procedures. Their ICV also was compared with those of an age- and gender-matched cohort and reviewed their rate of cranial expansion. The study included 21 children who presented sequentially with Crouzon (n = 13) or Apert (n = 8) syndrome between 1987 and 1991 and who subsequently underwent a standard first-stage cranio-orbital reconstruction by the senior author (J.C.P.) in conjunction with a pediatric neurosurgeon. The primary method of osteotomy and bone graft fixation varied (i.e., wires, microplates, miniplates, and screws). The series included 16 females and 5 males with an average age at the time of operation of 13 months (range, 6 to 46 months). The postoperative clinical follow-up ranged from 12 to 60 months at the time of the study's completion. Comparison of the IVCs of the Apert patients preoperatively and postoperative with age and gender control volumes showed that six of eight had volumes at least 2 SD above the mean. Postoperatively, the trend continued with all eight patients followed longitudinally; all maintained volumes in excess of 2 standard deviations above the mean. Preoperatively, for the Crouzon children evaluated, 12 of 13 had ICV values greater than the mean. When comparing the patients' postoperative volumes to the normative data, all 13 maintained values at or greater than the mean at the time of their postoperative determination. Ten of the 13 achieved ICVs at or greater than 2 SD above the mean. When reviewing each Crouzon patient's cranial capacity over time, 5 of the 13 approximated the normal growth curve whereas 6 of the 13 exceeded it. This study confirms that Apert patients are macrocephalic before and after standard cranio-orbital procedures carried out in childhood. For the majority of children born with Crouzon syndrome, the cranial capacity will exceed the mean early in life and expand at a rapid rate after cranio-orbital decompression. The biologic explanation for these findings remain unclear.

Acrocephalosyndactylia↗