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Biomedical subjects

H Christensen

Publications and source records attributed to H Christensen.

At least 109 records · Page 6Linked to original sources
PubMed2000

Renal functional outcome in unilateral hydronephrosis in newborn pigs.

PURPOSE: We followed the course of neonatally induced, partial unilateral ureteral obstruction in pigs and established whether early function or morphological evaluation of the hydronephrotic kidney is predictive of outcome. MATERIALS AND METHODS: In 25 piglets unilateral partial ureteropelvic obstruction was induced 2 days after birth, while 11 underwent sham operation. Only obstructed kidneys with significant dilatation at 4 weeks were included for further study. Renal function was assessed on renography using (99m)technetium-diaminetriaminepentaacetic acid differential uptake. According to the plasma clearance of (99m)technetium-diaminetriaminepentaacetic acid the glomerular filtration rate was determined at ages 4, 12 and 24 weeks. Kidney morphology was studied in parallel by magnetic resonance imaging. RESULTS: A total of 12 obstructed kidneys with grade 3 or 4 hydronephrosis fulfilled study inclusion criteria. Of 6 kidneys with a functional share of 40% or greater at age 4 weeks 2 deteriorated to less than 40% at 24 weeks, while 4 of 6 with a share of less than 40% at age 4 weeks improved to greater than 40% at 24 weeks. The single kidney glomerular filtration rate at 4 weeks did not correlate with that at 12 or 24 weeks but the rate at 12 weeks correlated with that at 24 weeks (r2 = 0.8140, p <0.001). Neither relative volume of the obstructed kidney nor length of the contralateral nonobstructed kidney correlated with functional share of the obstructed kidney at any age. CONCLUSIONS: Early evaluation of kidney function or volume, or contralateral kidney length did not predict the outcome of neonatally induced unilateral hydronephrosis in pigs.

Age Factors↗
PubMed1999

Smoking and mental health: results from a community survey.

OBJECTIVE: To assess the relationship of smoking with depression and anxiety symptoms and with risk factors for depression. DESIGN AND SETTING: A community survey conducted in Canberra in 1997. PARTICIPANTS: 2725 persons aged 18-79 sampled from the electoral roll. MAIN OUTCOME MEASURES: Smoking was investigated in relation to psychiatric symptoms (anxiety, depression, alcohol misuse), sociodemographic characteristics (age, sex, education, occupational status), social stressors (divorce, unemployment, financial difficulties, negative life events, childhood adversity), personality (extraversion, neuroticism, psychoticism), and social support (family and friends). RESULTS: Smokers had more depression and anxiety symptoms, more stressors and lower socioeconomic status compared with non-smokers. The association between smoking and psychiatric symptoms persisted even when stressors, socioeconomic characteristics and other factors were statistically controlled. CONCLUSIONS: Smoking is associated with poorer mental health. In helping patients to give up smoking, doctors need to be aware that some may have underlying mental health problems that require attention.

Adolescent↗
PubMed1999

Emotional response of participants to a mental health survey.

Following participation in a mental health survey of 2725 adults aged 18-79, respondents were asked if the questionnaire had made them feel distressed or depressed, and if it had been an intrusion on privacy or had made them feel good about themselves. While 5% reported feeling distressed, 3% depressed and 3% were concerned about privacy, 35% reported feeling good about themselves. The participants reporting negative feelings were more likely to be younger women, to be higher on negative personality measures, to report more anxiety and depression symptoms, and to have had more childhood adversity and lower social support. Those who reported positive feelings had higher positive personality scores, more social support and lower anxiety and depression. This group was more likely to be older women. Despite the sensitive nature of many of the questions, only a small percentage of respondents reported distress, while many found that the questionnaire had made them feel good about themselves. This is important information to present to Institutional Ethics Committees and to future participants in such studies.

Adolescent↗
PubMed1999

Pharmacokinetic interactions between microemulsion formulated cyclosporine A and diltiazem in renal transplant recipients.

OBJECTIVE: Bilateral cyclosporin A (CsA) and diltiazem pharmacokinetic interactions have previously been investigated, however, not with the new microemulsion preconcentrate formulation of CsA (Sandimmun Neoral). In addition, the pharmacokinetic effects on the pharmacological active metabolites of diltiazem have not previously been investigated. We performed a pharmacokinetic interaction study in renal transplant recipients, measuring both unmetabolised CsA and diltiazem in addition to three of the main metabolites of diltiazem (MA, M1, M2). METHODS: Nine CsA-treated renal transplant patients were treated with diltiazem, 90-120 mg b.i.d., for 4 weeks. Pharmacokinetic investigations were performed both before and at the end of the diltiazem treatment period. Six non-CsA-treated renal transplant patients served as controls of CsA interactions with diltiazem and its metabolites. RESULTS: Diltiazem treatment resulted in a significant mean increase in the area under the concentration time curve (AUC) for CsA of 51(8)% (P < 0.008) and a peak concentration (Cmax) of 34(8)% (P < 0.05), without altering time to peak concentration (tmax). CsA, however, did not significantly influence diltiazem pharmacokinetics, though two of the metabolites (M1 and M2) tended to be increased. CONCLUSIONS: Diltiazem interacts significantly with the pharmacokinetics of CsA in the new microemulsion formulation. Microemulsion-formulated CsA, however, did not show significant interaction with diltiazem pharmacokinetics.

Adult↗
PubMed1999

A simple and sensitive high-performance liquid chromatography assay of diltiazem and main metabolites in renal transplanted patients.

A sensitive and specific reversed-phase high-performance liquid chromatographic method was developed for determination of the benzothiazepine calcium channel blocker diltiazem and three of its main metabolites in human plasma. A solid-phase extraction method (C18) is described for isolating diltiazem and the metabolites N-demethyl-diltiazem (M(A)), deacetyldiltiazem (M1) and N-demethyl-deacetyl-diltiazem (M2) from human plasma spiked with trans-diltiazem as internal standard. Chromatographic analysis of the eluate was accomplished using a reversed-phase column (C8) and a mobile phase consisting of acetonitrile, potassium dihydrogen phosphate-buffer (pH 2.9), triethylamine and methanol (280:598:2:90 v/v/v/v). The limit of detection was 5 ng/ml for diltiazem and 2.5 ng/ml for the metabolites (UV detection). Recoveries were > 75% for all substances. Precision analysis indicated a coefficient of variation below 5% for both diltiazem and metabolites at plasma concentrations ranging from 30 to 120 ng/ml for diltiazem and from 15 to 60 ng/ml for the metabolites. The accuracy was < 3% for diltiazem at all concentrations investigated. Metabolites showed an accuracy of < 7% at higher concentrations, however at low concentration the accuracy was < 16%. A pilot study has been performed in order to study whether the method was applicable to patients and volunteers. Plasma samples from renal transplanted patients treated with cyclosporin A and healthy volunteers did not show any interference by cyclosporin A with the determination of diltiazem and metabolites.

Adult↗
PubMed1999

Upper trapezius muscle activity patterns during repetitive manual material handling and work with with a computer mouse.

Firstly, upper trapezius EMG activity patterns were recorded on the dominant side of 6 industrial production workers and on the side operating a computer mouse of 14 computer-aided design (CAD) operators to study differences in acute muscular response related to the repetitiveness of the exposure. The work tasks were performed with median arm movement frequencies ranging from 5 min(-1) to 13 min(-1) and were characterized by work cycle times ranging from less than 30 sec to several days. However, the static and median EMG levels and EMG gap frequencies were similar for all work tasks indicating that shoulder muscle loads may be unaffected by large variations in arm movement frequencies and work cycle times. An exposure variation analyses (EVA) showed that the EMG activity patterns recorded during production work were more repetitive than during CAD work, whereas CAD work was associated with more static muscle activity patterns, both may be associated with a risk of developing musculoskeletal symptoms. Secondly, upper trapezius EMG activity patterns recorded on the mouse side of the CAD operators were compared with those recorded on the non-mouse side to study differences in muscular responses potentially related to the risk of developing shoulder symptoms which were more prevalent on the mouse side. The number of EMG gaps on the mouse side were significantly lower than the values for the upper trapezius on the non-mouse side indicating that more continuous activity was present in the upper trapezius muscle on the mouse side and EVA analyses showed a more repetitive muscle activity pattern on the mouse side. These findings may be of importance to explain differences in the prevalence of shoulder symptoms.

Adult↗
PubMed1999

Age differences in depression and anxiety symptoms: a structural equation modelling analysis of data from a general population sample.

BACKGROUND: There is debate as to whether the elderly are really at lower risk for depressive disorders, or whether endorsement of symptoms is artefactually low. The present paper assesses the effects of age on anxiety and depression, and examines whether age has direct effects on self-report of individual symptoms independent of its effect on the underlying dimensions of anxiety and depression. METHODS: Structural equation modelling was used to assess the structure of the items and their associations with age and a number of demographic variables. The sample of 2622 participants aged between 18 and 79 years from Canberra (Australia) was drawn from the Electoral Roll. Two instruments were used: the anxiety and depression scales of Goldberg et al. (1988) and the Personal Disturbance Scale from the DSSI of Bedford et al. (1976). RESULTS: Both scales were found to fit satisfactorily to a two factor model. Age correlated negatively with depression. After controlling for the effects of gender, marital status, education and financial difficulty, direct effects of age were found on items from both instruments, indicating that certain depression items were associated with a differential probability of endorsement in older people, even when the level of depression was equal to that of younger people. Items with direct age effects reflected physical (feeling slowed down; waking early) and psychological (hopeless about the future) components of depression. Direct effects of age on items from both anxiety scales were also found. CONCLUSIONS: The nature of the depression and anxiety experienced by younger and older people may differ qualitatively. Depression may be associated with an increase in somatic symptoms linked to physical changes and to an increase in endorsement of items which reflect the narrowing of opportunities in the long-term.

Adolescent↗
PubMed1999

An analysis of diversity in the cognitive performance of elderly community dwellers: individual differences in change scores as a function of age.

This longitudinal study investigated whether age is associated with increases in interindividual variability across 4 ability domains using a sample of 426 elderly community dwellers followed over 3.5 years. Interindividual variability in change scores increased with age for memory, spatial functioning, and speed but not for crystallized intelligence for the full sample and in a subsample that excluded dementia or probable dementia cases. Hierarchical regression analyses indicated that being female, having weaker muscle strength, and having greater symptoms of illness and greater depression were associated with overall greater variability in cognitive scores. Having a higher level of education was associated with reduced variability. These findings are consistent with the view that there is a greater range of responses at older ages, that certain domains of intelligence are less susceptible to variation than others and that variables other than age affect cognitive performance in later life.

Activities of Daily Living↗
PubMed1999

Lipid domains of mycobacteria studied with fluorescent molecular probes.

The complex mycobacterial cell envelope is recognized as a critical factor in our failure to control tuberculosis, leprosy and other non-tuberculous pathogens. Although its composition has been extensively determined, many details regarding the organization of the envelope remain uncertain. This is particularly so for the non-covalently bound lipids, whose natural distribution may be disrupted by conventional biochemical or cytological techniques. In order to study the native organization of lipid domains in the mycobacterial envelope, we have applied a range of fluorescent lipophilic probes to live mycobacteria, including Mycobacterium smegmatis, Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium gadium and Mycobacterium aurum, and analysed the resultant signals by fluorescence microscopy and digital image processing. Five key features were observed: (i) the presence of both envelope and intracellular lipid domains; (ii) differential localization of probes into these domains influenced predominantly by their hydrophobicity, as modelled by their calculated octanol:water partition coefficients and by their amphiphilicities; (iii) uneven distribution of lipophilic material in the envelope; (iv) selective labelling of septal regions of the envelope; and (v) modification of labelling patterns by additional treatments such as fluorescence quenching antibodies, detergents and solvents. Using this last approach, a coherent cell envelope lipid domain was demonstrated outside the cytoplasmic membrane and, for the first time, the proposed covalently linked mycolyl-arabinogalactan-peptidoglycan macromolecular complex was imaged directly. The use of fluorescent probes and high-resolution fluorescence microscopy has enabled us to obtain a coherent view of distinct lipid domains in mycobacteria. Further application of this approach will facilitate understanding of the role of lipids in the physiology of these organisms.

Cell Membrane↗
PubMed1999

Attitudes towards people with a mental disorder: a survey of the Australian public and health professionals.

OBJECTIVE: The aim of this paper was to compare the Australian public's attitudes towards people who have been treated for a mental disorder with the attitudes of general practitioners, psychiatrists and clinical psychologists. METHOD: The study involved a household survey of 2031 members of the Australian public and a postal survey of 872 general practitioners, 1128 psychiatrists and 454 clinical psychologists. Survey participants were presented with a vignette describing a person with schizophrenia or one with depression. They were asked opinions about the person's long-term outcome in various areas of life after receiving treatment. Participants were also asked whether they thought the person described would be discriminated against by others. RESULTS: Both the public and professionals rated outcomes as poorer and discrimination as more likely for the person with schizophrenia than for the one with depression. The professionals made more negative ratings than the public, although the clinical psychologists had similar attitudes to the public about depression. CONCLUSIONS: Compared to the public, health professionals rate long-term outcomes more negatively and discrimination as more likely. It is possible that these more negative attitudes are realistic, being based on greater knowledge of mental disorders. However, professional attitudes may be biased by greater contact with patients who have chronic or recurrent disorders. Either way, health professionals need to be aware of the effects that their negative attitudes might have on patients and the public.

Adolescent↗
PubMed1999

Fishbone perforation through a Meckel's diverticulum: a rare laparoscopic diagnosis in acute abdominal pain.

The use of diagnostic laparoscopy in acute abdominal pain, especially when patients have been admitted for acute pain in the lower abdominal quadrants, improves the accuracy of diagnosis and leads to improvements in treatment procedures. A case is reported of a 24-year-old woman admitted under suspicion of appendicitis. The appendix was found to be normal, and a perforation caused by a fishbone was discovered in a Meckel's diverticulum. The diverticulum was resected by a combined laparoscopic and open procedure. Diagnostic laparoscopy should be performed routinely in cases of acute abdominal pain in the lower quadrants of suspected appendiceal origin to avoid overlooking other causes of the symptoms.

Abdomen, Acute↗
PubMed1999

Identification of lactic acid bacteria from chili bo, a Malaysian food ingredient.

Ninety-two strains of lactic acid bacteria (LAB) were isolated from a Malaysian food ingredient, chili bo, stored for up to 25 days at 28 degreesC with no benzoic acid (product A) or with 7,000 mg of benzoic acid kg-1 (product B). The strains were divided into eight groups by traditional phenotypic tests. A total of 43 strains were selected for comparison of their sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) whole-cell protein patterns with a SDS-PAGE database of LAB. Isolates from product A were identified as Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus farciminis, Pediococcus acidilactici, Enterococcus faecalis, and Weissella confusa. Five strains belonging to clusters which could not be allocated to existing species by SDS-PAGE were further identified by 16S rRNA sequence comparison. One strain was distantly related to the Lactobacillus casei/Pediococcus group. Two strains were related to Weissella at the genus or species level. Two other strains did not belong to any previously described 16S rRNA group of LAB and occupied an intermediate position between the L. casei/Pediococcus group and the Weissella group and species of Carnobacterium. The latter two strains belong to the cluster of LAB that predominated in product B. The incidence of new species and subspecies of LAB in chili bo indicate the high probability of isolation of new LAB from certain Southeast Asian foods. None of the isolates exhibited bacteriocin activity against L. plantarum ATCC 14917 and LMG 17682.

DNA, Bacterial↗
PubMed1999

Counting and size classification of active soil bacteria by fluorescence in situ hybridization with an rRNA oligonucleotide probe.

A fluorescence in situ hybridization (FISH) technique based on binding of a rhodamine-labelled oligonucleotide probe to 16S rRNA was used to estimate the numbers of ribosome-rich bacteria in soil samples. Such bacteria, which have high cellular rRNA contents, were assumed to be active (and growing) in the soil. Hybridization to an rRNA probe, EUB338, for the domain Bacteria was performed with a soil slurry, and this was followed by collection of the bacteria by membrane filtration (pore size, 0.2 micrometer). A nonsense probe, NONEUB338 (which has a nucleotide sequence complementary to the nucleotide sequence of probe EUB338), was used as a control for nonspecific staining. Counting and size classification into groups of small, medium, and large bacteria were performed by fluorescence microscopy. To compensate for a difference in the relative staining intensities of the probes and for binding by the rhodamine part of the probe, control experiments in which excess unlabelled probe was added were performed. This resulted in lower counts with EUB338 but not with NONEUB338, indicating that nonspecific staining was due to binding of rhodamine to the bacteria. A value of 4.8 x 10(8) active bacteria per g of dry soil was obtained for bulk soil incubated for 2 days with 0.3% glucose. In comparison, a value of 3.8 x 10(8) active bacteria per g of dry soil was obtained for soil which had been air dried and subsequently rewetted. In both soils, the majority (68 to 77%) of actively growing bacteria were members of the smallest size class (cell width, 0.25 to 0.5 micrometer), but the active (and growing) bacteria still represented only approximately 5% of the total bacterial population determined by DAPI (4', 6-diamidino-2-phenylindole) staining. The FISH technique in which slurry hybridization is used holds great promise for use with phylogenetic probes and for automatic counting of soil bacteria.

Bacteria↗
PubMed1999

Health, cognitive, and psychosocial factors as predictors of mortality in an elderly community sample.

STUDY OBJECTIVE: To examine whether cognitive and psychosocial factors predict mortality once physical health is controlled. DESIGN: A prospective study of community dwelling elderly. Mortality was assessed over a period of 3-4 years after the baseline assessment of predictors. The data were analysed using the Cox proportional hazards model. SETTING: Canberra and Queanbeyan, Australia. PARTICIPANTS: A sample of 897 people aged 70 or over and living in the community, drawn from the compulsory electoral roll. RESULTS: For the sample as a whole, the significant predictors of mortality were male sex, poor physical health, poor cognitive functioning, and low neuroticism. Men had an adjusted relative risk of mortality of 2.5 compared with women. For the male sub-sample, poor self rated health and a poor performance on a speeded cognitive task were significant predictors, while for women, greater disability, low systolic blood pressure, and a low score on a dementia screening test were the strongest predictors. CONCLUSIONS: Mortality was predicted by physical ill health and poor cognitive functioning. Psychosocial factors such as socioeconomic status, psychiatric symptoms, and social support did not add to the prediction of mortality, once sex, physical health, and cognitive functioning were controlled. Mortality among men was more than twice that of women, even when adjusted for other predictors.

Aged↗
PubMed1999

Effect of experimental diabetes and growth hormone administration on the strength of colonic anastomoses in rats.

The influence of growth hormone (GH; 2 mg/kg/day) administration on the mechanical breaking strength of colonic anastomoses in diabetic rats has been investigated on the day of operation (suture binding capacity) and after 4 and 7 days of healing. In diabetic rats, the suture binding capacity was decreased by 26% in both ultimate load and relative failure energy. After 4 days of healing, no difference was observed between control and diabetic animals. After 7 days, relative failure energy in the diabetic animals was reduced by 33%. GH administration to diabetic animals did not alter strength during the first week of healing. We found an increased circumference (33%) and defatted dry weight (22%) of the colon in diabetic rats. In conclusion, diabetes impairs the suture-binding capacity of the colon in rats, while there is only little influence on healing in the following week. GH administration could not influence the strength of colonic anastomoses in diabetic animals.

Anastomosis, Surgical↗
PubMed1999

Transient myeloproliferative disorder (transient leukemia) and hematologic manifestations of Down syndrome.

Transient Myeloproliferative Disorder (Transient Leukemia) is found in approximately 10% of newborn infants with Down Syndrome. It is characterized by the large numbers of megakaryoblasts in the peripheral blood, variable thrombocytopenia and, in a minority of cases, by a lethal course with hydrops fetalis or progressive hepatic fibrosis. Evidence is presented that this disease is truly leukemia, which, in most cases, recovers spontaneously. There is evidence that hematopoiesis is abnormal in Down Syndrome children who do not have leukemia. These abnormalities of red cells, platelets, and granulocytes are reviewed.

Child, Preschool↗