Biomedical subjects

H Christensen

Publications and source records attributed to H Christensen.

At least 127 records · Page 7Linked to original sources

PubMed1999

[Prevalence of cardial or fundic mucosa and Helicobacter pylori in the squamous-columnar mucosa in patients with chronic patological gastroesophageal reflux without intestinal metaplasia comparated with controls].

BACKGROUND: The mucosa distal to the endoscopic mucosal change zone can have easily diagnosed early alterations, in patients with chronic gastroesophageal reflux. AIM: To determine the type of mucosa existent in the zone distal to the squamous-columnar junction in patients with chronic gastroesophageal reflux without intestinal metaplasia. PATIENTS AND METHODS: One hundred thirty four controls and 208 patients with chronic gastroesophageal reflux lasting two years were studied. Forty three of these patients had a normal endoscopy, 54 had an erosive esophagitis and 111 had a short columnar epithelium covering the distal esophagus, without intestinal metaplasia. In all subjects, four biopsies were obtained from a zone distal to the squamous-columnar junction and two from the distal gastric antrum. RESULTS: In 59% of control subjects, fundic mucosa was present in the zone distal to the squamous-columnar junction. Cardial mucosa was present in the rest. In patient with chronic gastroesophageal reflux, cardial mucosa was predominant. Helicobacter pylorii infection decreased along with increasing extension of cardial mucosa covering the distal esophagus. CONCLUSIONS: In patients with chronic gastroesophageal reflux there is a metaplasia of fundic mucosa towards cardial mucosa. On the other hand, Helicobacter pylorii infection decreases gradually.

Adolescent↗

PubMed1998

[Disseminated peritoneal leiomyomatosis].

Disseminated peritoneal leiomyomatosis is usually discovered incidentally and symptoms are unusual. It occurs only in women. The lesions are completely benign and apparently undergo spontaneous regression, therefore minimal or no treatment is indicated after the diagnosis is confirmed by biopsy.

Diagnosis, Differential↗

PubMed1998

Characterisation of non-maternal serum proteins in amniotic fluid at weeks 16 to 18 of gestation.

Proteins found in amniotic fluid are mainly serum proteins, probably of maternal origin. About 5% of the total protein concentration has the potential of being fetal or decidual in origin. Only a few of these proteins have been isolated and characterised. In order to describe the foetal and decidual components in amniotic fluid more extensively, a polyspecific antiserum to amniotic fluid at weeks 16-18 of gestation was raised. Specificities in the antiserum to serum proteins were removed by adsorption. Several proteins of non-serum protein origin reacted with the antiserum. Three of these proteins were chosen for isolation and further characterisation. With the use of immunological methods, SDS-PAGE and N-terminal sequencing we identified two of the proteins as C-terminal propeptides of procollagen Type I and Type III, which have not hitherto been described in amniotic fluid. The third protein, called here protein-4, showed up as homologous to fetal antigen-1 (FA-1) and human dlk, containing EGF-like domains and associated with growth in neuroendocrine tissues and tumours.

Amino Acid Sequence↗

PubMed1998

Phylogenetic relationships of Salmonella based on DNA sequence comparison of atpD encoding the beta subunit of ATP synthase.

DNA sequences covering 57% of atpD encoding the beta subunit of ATP synthase were determined for 16 strains of Salmonella enterica, two strains of S. bongori, and one strain each of Citrobacter freundii and Yersinia enterocolitica, and comparison was made with the published Escherichia coli and Enterobacter aerogenes sequences. The phylogenetic tree based on maximum-likelihood analysis showed separation of the subspecies of S. enterica except for two serotypes of subspecies II which were unsupported by a common node. The two serotypes of S. bongori were separated from S. enterica and related to the serotypes of subspecies II. A tight relationship was found between S. enterica subspecies IIIa consisting of monophasic serotypes and subspecies IIIb consisting of diphasic serotypes. This is in conflict with results obtained for most other housekeeping genes and the 23S rRNA gene separating mono- from diphasic subspecies.

Amino Acid Sequence↗

PubMed1998

Psychotic symptoms in the elderly: a prospective study in a population sample.

BACKGROUND: Most of what is known about psychotic symptoms in older persons is based on hospital series of severe disorders. METHOD: In the course of a longitudinal community-based survey of older persons, the presence of psychotic symptoms was assessed on two occasions 3-4 years apart. RESULTS: The point prevalence was 5.7%. Risk factors were cognitive impairment, living alone, being male, having had limited education, social isolation, poor health and depressive symptoms. Of the 65 persons who were symptomatic at the start, only six of those still alive had one or more psychotic symptoms after 3-4 years. The incidence was 6.0% over a period of 3.6 years. CONCLUSIONS: Risk factors for psychotic symptoms in later life lie in age-related cognitive impairment in interaction with a range of environmental and psychosocial variables.

Aged↗

PubMed1998

Motor unit activation patterns during concentric wrist flexion in humans with different muscle fibre composition.

Muscle activity was recorded from the flexor carpi radialis muscle during static and dynamic-concentric wrist flexion in six subjects, who had exhibited large differences in histochemically identified muscle fibre composition. Motor unit recruitment patterns were identified by sampling 310 motor units and counting firing rates in pulses per second (pps). During concentric wrist flexion at 30% of maximal exercise intensity the mean firing rate was 27 (SD 13) pps. This was around twice the value of 12 (SD 5) pps recorded during sustained static contraction at 30% of maximal voluntary contraction, despite a larger absolute force level during the static contraction. A similar pattern of higher firing rates during dynamic exercise was seen when concentric wrist flexion at 60% of maximal exercise intensity [30 (SD 14) pps] was compared with sustained static contraction at 60% of maximal voluntary contraction [19 (SD 8) pps]. The increase in dynamic exercise intensity was accomplished by recruitment of additional motor units rather than by increasing the firing rate as during static contractions. No difference in mean firing rates was found among subjects with different muscle fibre composition, who had previously exhibited marked differences in metabolic response during corresponding dynamic contractions. It was concluded that during submaximal dynamic contractions motor unit firing rate cannot be deduced from observations during static contractions and that muscle fibre composition may play a minor role.

Adult↗

PubMed1998

Musculoskeletal disorders among dentists and variation in dental work.

The purpose was to assess risk factors in dentistry which may contribute to musculoskeletal disorders. A questionnaire was used to identify common work tasks, and to estimate one year prevalence for troubles (65% for the neck/shoulder, 59% for the low back). In a field study working postures and electromyography (shoulder/neck) were registered during the three most common work tasks. Prolonged neck flexion and upper arm abduction were found, as well as high static muscle activity levels (splenius and trapezius muscles). No differences between work tasks were found regarding postures, frequencies of movements or muscle activity. Alterations between the three work tasks do not produce sufficient variation to reduce musculoskeletal load on the neck and shoulders.

Adult↗

PubMed1998

Rates of forgetting in Alzheimer dementia.

Patients diagnosed with Alzheimer's disease (AD) were compared with healthy controls on a picture recognition task, a forced choice word recognition task, a forced choice design recognition task, a picture recall task and a stem completion task. Performance on recognition and word stem completion was assessed at 1, 10 and 20 min after exposure to experimental stimuli, as these are delays across which previous studies had suggested there might be differing forgetting rates. AD patients did not show significantly faster rates of forgetting relative to controls on picture recognition, design recognition, word recognition or stem completion, after levels of learning had been matched as closely as possible. Moreover, once initial learning was equated in a small number of subjects, there were no qualitative differences between AD patients and controls following inclusion and exclusion instructions on the stem completion task. In particular, those AD patients who were matched to controls for initial levels of "recollection" showed comparable forgetting rates in recollection (or cued recall). Although matching was more difficult for a picture recall task, both the main analysis and subgroup analysis indicated faster forgetting in the AD group than controls, suggesting a difference between "free recall" and recognition or cued recall measures, comparable with the finding in a parallel study of organic amnesia.

Aged↗

PubMed1998

Symptoms of depression and anxiety during adult life: evidence for a decline in prevalence with age.

BACKGROUND: To test the hypothesis that the prevalence, in the general population, of symptoms of depression and anxiety declines with age. METHODS: A general population sample of 2725 persons aged 18 to 79 years was administered two inventories for current symptoms of depression and anxiety, together with measures of neuroticism and of exposures that may confer increased risk of such symptoms. RESULTS: Symptoms of depression showed a decline with age in both men and women. For anxiety, the decline was statistically significant for women but not consistently so for men. For the risk factors examined, there was a decline with age in the neuroticism score, the frequency of adverse life events, being seriously short of money and having had parents who separated or divorced. Further analysis showed that the association between age and a declining symptom score cannot be entirely attributed to these risk factors, with the single exception of neuroticism. The latter is itself likely to be contaminated by current symptoms. CONCLUSION: Unless these findings are due to bias in the sample of those who agreed to participate, they add to the evidence that symptoms of depression and to a lesser extent of anxiety decline in prevalence with age. Some risk factors also decline with age. It now has to be determined if these cross-sectional observations are also to be found in longitudinal data; and what process may underlie this striking change in mental health during adulthood.

Adolescent↗

PubMed1998

An association study of a functional polymorphism of the serotonin transporter gene with personality and psychiatric symptoms.

A functional polymorphism in the regulatory region of the serotonin transporter gene has been reported to be associated with anxiety-related personality traits. We attempted to replicate this finding in an association study involving 759 Caucasians selected from the general Australian population. We found no associations with personality traits (including neuroticism, negative affect and behavioral inhibition), anxiety and depressive symptoms, or alcohol misuse.

Alcoholism↗

PubMed1998

Occupation type as a predictor of cognitive decline and dementia in old age.

OBJECTIVE: To assess whether an individual's main occupation predicts cognitive decline or dementia. METHODS: The data were taken from a longitudinal study of 518 men aged 70 or over. Main occupation was coded into one of John Holland's six occupational categories. The subjects completed four cognitive tests and were diagnosed for dementia on two occasions three and a half years apart. The cognitive tests were the Mini-Mental State Examination, Episodic Memory Test, Symbol-Letter Modalities Test and National Adult Reading Test. Informants also completed the Informant Questionnaire on Cognitive Decline in the Elderly. Dementia was diagnosed by the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised (DSM-III-R) and ICD-10 criteria using the Canberra Interview for the Elderly. RESULTS: Cross-sectional analysis of the wave 1 data showed that the realistic occupations, which include trade, technical and some service occupations, had poorer cognitive performance and a higher prevalence of DSM-III-R dementia. These differences held even when age, education and native English were statistically controlled. The greatest occupational difference was on the National Adult Reading Test, which estimates pre-morbid ability. By contrast, there were no occupational differences in longitudinal change in cognitive test performance, informant reports of cognitive decline or incident cases of dementia over three and a half years. CONCLUSION: Cross-sectional occupational differences on cognitive tests and in dementia prevalence are due to differences in pre-morbid ability rather than to differences in rate of cognitive decline.

Aged↗

PubMed1998

Effects of hyperventilation and hypocapnic/normocapnic hypoxemia on renal function and lithium clearance in humans.

BACKGROUND: Using the renal clearance of lithium as an index of proximal tubular outflow, this study tested the hypothesis that acute hypocapnic hypoxemia decreases proximal tubular reabsorption to the same extent as hypocapnic normoxemia (hyperventilation) and that this response is blunted during normocapnic hypoxemia. METHODS: Eight persons were studied on five occasions: (1) during inhalation of 10% oxygen (hypocapnic hypoxemia), (2) during hyperventilation of room air leading to carbon dioxide values similar to those with hypocapnic hypoxemia, (3) during inhalation of 10% oxygen with the addition of carbon dioxide to produce normocapnia, (4) during normal breathing of room air through the same tight-fitting face mask as used on the other study days, and (5) during breathing of room air without the face mask. RESULTS: Hypocapnic and normocapnic hypoxemia and hyperventilation increased cardiac output, respiratory minute volume, and effective renal plasma flow. Glomerular filtration rate remained unchanged on all study days. Calculated proximal tubular reabsorption decreased during hypocapnic hypoxemia and hyperventilation but remained unchanged with normocapnic hypoxemia. Sodium clearance increased slightly during hypocapnic and normocapnic hypoxemia, hyperventilation, and normocapnic normoxemia with but not without the face mask. CONCLUSIONS: The results indicate that (1) respiratory alkalosis with or without hypoxemia decreases proximal tubular reabsorption and that this effect, but not renal vasodilation or natriuresis, can be abolished by adding carbon dioxide to the hypoxic gas; (2) the increases in the effective renal plasma flow were caused by increased ventilation rather than by changes in arterial oxygen and carbon dioxide levels; and (3) the natriuresis may be secondary to increased renal perfusion, but application of a face mask also may increase sodium excretion.

Adult↗

PubMed1998

Phylogenetic relationships of Salmonella based on rRNA sequences.

To establish the phylogenetic relationships between the subspecies of Salmonella enterica (official name Salmonella choleraesuis), Salmonella bongori and related members of Enterobacteriaceae, sequence comparison of rRNA was performed by maximum-likelihood analysis. The two Salmonella species were separated by 16S rRNA analysis and found to be closely related to the Escherichia coli and Shigella complex by both 16S and 23S rRNA analyses. The diphasic serotypes S. enterica subspp. I and VI were separated from the monophasic serotypes subspp. IIIa and IV, including S. bongori, by 23S rRNA sequence comparison.

Base Sequence↗

PubMed1998

Predictors of GP service use: a community survey of an elderly Australian sample.

As part of a study of an elderly community-dwelling Australian population, predictors of general practitioner (GP) service use were identified. The sample of 897 persons, aged 70 years or older and living in Canberra and Queanbeyan, were interviewed about their health and well-being. Data on the number of GP visits in the following 12-month period were obtained from the Health Insurance Commission. There were important gender differences in the prediction of both contact and volume of service use. Need variables (physical health in men, and disability and anxiety in women) were the most important predictors. Men who were older or who had lower occupational status used more medical services, as did women with less education or higher levels of extraversion. Men with lower social support were less likely to contact a GP, but social support was not related to volume of service use for either men or women. Since at most 21% of the variance in the volume of GP service use could be explained, despite the wide range of predictors considered and the different statistical approaches adopted, better measures of service use and predictors need to be developed.

Activities of Daily Living↗

PubMed1998

Outcome of lithium prophylaxis: a prospective follow-up of affective disorder patients assigned to high and low serum lithium levels.

The purpose of the study was to examine the outcome of long-term lithium treatment in consecutively admitted affective disorder patients assigned to high and low serum lithium levels. A total of 91 patients were diagnosed according to DSM-III criteria and randomly allocated to two open treatment groups in which prophylactic lithium was administered in high (serum lithium 0.8-1.0 mmol L-1) and low (serum lithium 0.5-0.8 mmol L-1) doses, respectively. The patients were followed for 2 years or until discontinuation of lithium treatment or readmission to hospital for recurrence of affective illness. The main outcome of the treatment groups was compared with Kaplan-Meier survival curves and by Cox regression analysis. A total of 31 patients (34%) completed 24 months of prophylactic lithium treatment without recurrence and readmission to hospital. In total, 18 patients (20%) suffered a recurrence on lithium, and 42 patients (46%) discontinued lithium or were lost to follow-up. No effect of treatment group was seen, either for the total patient group or for the large subgroup of bipolar patients when analysed separately. A number of patients did not maintain their original assignment to the high serum lithium levels group. The results were analysed both according to assignment and according to actual serum lithium levels. Abuse of alcohol or medication was associated with a poor outcome. Only one third of the patients completed 2 years of lithium prophylaxis successfully. No difference in the protection against recurrences was observed between patients maintained on high and low serum lithium levels.

Adult↗

PubMed1998

Diltiazem modulates cyclosporin A induced renal hemodynamic effects but not its effect on plasma endothelin-1.

Cyclosporin A (CsA) has been reported to induce major acute renal hypoperfusion that may be antagonised by calcium channel blockers. The vasoconstrictive peptide endothelin-1 (ET-1) has been proposed as a mediator of CsA induced hypoperfusion. We investigated the acute effects of the new CsA formulation (Sandimmun Neoral) in 8 renal transplant patients on triple immunosuppressive therapy before and following slow-release diltiazem treatment in a dose of 90-120 mg b.i.d for 4 weeks. CsA significantly increased mean arterial blood pressure by 6 +/- 2 mmHg (p < 0.05) during the first 3 h after administration. This effect was abolished by diltiazem treatment, also reducing blood pressure by 12 +/- 3 mmHg (p < 0.05) 3-9 h after administration. CsA administration induced a maximum reduction in renal blood flow of 20 +/- 8% (p < 0.05) 5 h after ingestion and a concomitant reduction in glomerular filtration rate of 18 +/- 7% (p < 0.05). The filtration fraction increased by a maximum of 13 +/- 7% (p < 0.05) after 4 h as did the calculated fractional proximal reabsorption by 14 +/- 4% (p < 0.05). All these acute renal effects were abolished by diltiazem administration. Concurrent with the maximum renal hemodynamic effects, plasma ET-1 was elevated with a peak increase of about 40% 4-5 h after CsA ingestion. Diltiazem treatment had no effect on the increase in plasma ET-1 following CsA administration. These findings suggest that CsA induced acute vasoconstriction and renal hypoperfusion are mediated by ET-1 and that diltiazem treatment abolishes these pharmacodynamic effects of CsA despite persistent increase of plasma ET-1 levels.

Adult↗

PubMed1998

Job demands, muscle activity and musculoskeletal symptoms in relation to work with the computer mouse.

OBJECTIVES: This study assessed work postures, movements, psychosocial job demands, and shoulder and wrist extensor muscle activity and registered the prevalence of musculoskeletal symptoms of computer-aided design (CAD) operators. METHODS: A questionnaire survey was used to study the use of the computer mouse, psychosocial work factors, and musculoskeletal symptoms among 149 CAD operators. A workplace study was performed using observations, electrogoniometers on the wrists, and electromyography to measure exposures and physiological responses during CAD work among a subgroup of the CAD operators. RESULTS: Musculoskeletal symptoms were far more prevalent for the arm or hand operating the mouse than for the other arm or hand, and women were more affected than men. The symptoms may be related to such risk factors as repetitive movements, static postures (eg, ulnar-deviated and extended wrist on the mouse side), and static muscular activation patterns. The risk factors were present due to continuous mouse use and possibly also due to high demands for mental attentiveness, precision, and information processing. CONCLUSIONS: Exposure during work with a computer mouse may present a risk for developing musculoskeletal symptoms. Improvements should focus on introducing more variation.

Adult↗

PubMed1997

Impact of pet ownership on elderly Australians' use of medical services: an analysis using Medicare data.

OBJECTIVES: To determine whether pet ownership by elderly people is associated with lower use of health services. DESIGN: Survey of physical and mental health, and retrospective 12-month review of Medicare records of the number of general practitioner and specialist services. PARTICIPANTS AND SETTING: Elderly people living in Canberra (Australian Capital Territory) and Queanbeyan (New South Wales), surveyed in 1994 for the second stage of a larger longitudinal study. RESULTS: Elderly pet owners did not differ from non-owners on any of the physical or mental health measures or in use of health services. CONCLUSION: Given the high use of health services by older people, our findings suggest that the claim that pet ownership leads to savings in health services should be viewed with caution.

Aged↗