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Biomedical subjects

V Krause

Publications and source records attributed to V Krause.

At least 19 recordsLinked to original sources
PubMed2005

Seroprevalence of Burkholderia pseudomallei in East Timorese refugees: implications for healthcare in East Timor.

Melioidosis is a disease with protean clinical manifestations caused by the bacterium Burkholderia pseudomallei. It is endemic in countries surrounding the newly independent East Timor, but has yet to be isolated or demonstrated serologically in that country. One illness that can be clinically indistinguishable from melioidosis is pulmonary tuberculosis, a condition with a very high prevalence in East Timor. We used an indirect hemagglutination test (IHA) to measure antibodies to B. pseudomallei in 407 East Timorese evacuated to Darwin, Australia, in September 1999. Assuming a positive IHA titer as > or = 1:40, the overall seroprevalence rate was 17.0%, in keeping with other seroprevalence studies from the region. The IHA titres ranged up to 1:320. After adjusting for age, females were 2.5 times more likely to be seropositive than males (p = 0.0001). There was an inverse relationship between seropositivity and age. This study shows that exposure to B. pseudomallei occurs in East Timor melioidosis is also likely to occur. Due to the lack of laboratory facilities at present, it may be some time before a laboratory-confirmed case proves that melioidosis occurs. In the meantime, clinicians in East Timor should include melioidosis in the differential diagnosis of the many conditions that it may mimic.

Adolescent↗
PubMed2004

Noninvasive assessment of the injured human spinal cord by means of functional magnetic resonance imaging.

STUDY DESIGN: A magnetic resonance imaging technique that enables indirect detection of neuronal activity has been developed for the spinal cord. In the present study, this method, spinal functional magnetic resonance imaging (fMRI), is applied to the first study of the injured spinal cord, with the goal of better clinical assessment of the entire cord. OBJECTIVES: The objectives of this project are: (1) to investigate the neuronal activity that can be detected in the spinal cord caudal to a chronic injury by means of spinal fMRI, and (2) to develop spinal fMRI as a clinical diagnostic tool. SETTING: Institute for Biodiagnostics, National Research Council of Canada, Winnipeg, Manitoba, Canada. METHODS: fMRI of the spinal cord was carried out in 27 volunteers with cervical or thoracic spinal cord injuries (SCIs). Of these volunteers, 18 had complete injuries, and nine had incomplete injuries. Spinal fMRI was carried out in a 1.5 T clinical MR system, using established methods. Thermal stimulation at 10 degrees C was applied to the fourth lumbar dermatome on each leg, and images were obtained of the entire lumbar spinal cord. RESULTS: Areas of neuronal activity were consistently observed in the lumbar spinal cord in response to the thermal stimulation, even when the subjects had no awareness of the sensation. The pattern of activity was notably different compared with noninjured subjects. In general, subjects with complete SCI showed absent or diminished dorsal gray matter activity, but had enhanced ventral activity, particularly contralateral to the stimulation. CONCLUSIONS: Spinal fMRI is able to provide a noninvasive assessment of the injured spinal cord that does not depend on the patient's perception of the stimulus being applied. This work was carried out on a standard clinical MRI system without modification, and so is readily applicable in most MR units. SPONSORSHIP: This work was funded by a grant from the Canadian Institutes of Health Research (CIHR).

Action Potentials↗
PubMed2004

Pilot study of dermal and subcutaneous fat structures by MRI in individuals who differ in gender, BMI, and cellulite grading.

BACKGROUND/AIMS: Puckered, dimply skin on the thighs, hips, and buttocks is known as cellulite. The cause of cellulite is not known, although there are a number of different hypotheses. In this study, we use magnetic resonance (MR) micro-imaging to study cellulite skin. To the best of our knowledge, this is the first reported MR study of cellulite. METHODS: High-resolution in vivo MR images of the postlateral thigh skin of two male groups and four female groups were obtained. Subjects were grouped according to their body mass index (BMI) and cellulite grade. A qualitative assessment of how MRI can be used to differentiate skin tissue at different levels of cellulite grading was performed. RESULTS: We found that changes in skin architecture with cellulite can be visualized by in vivo MR micro-imaging. The skin fat layers beneath the dermis and down to the level of muscles are well visualized in the images. Also, the diffuse pattern of extrusion of underlying adipose tissue into dermis is clearly imaged, and was found to correlate with cellulite grading. We also show that other skin tissue parameters such as (a) the percentile of adipose vs. connective tissue in a given volume of hypodermis and (b) the percentile of hypodermic invaginations inside the dermis are correlated with cellulite grade. CONCLUSION: MR images can be interpreted to measure tissue parameters correlated with cellulite. Considering that we had only three subjects in each group, the achievements of this pilot study were highly satisfactory. We have shown that the in vivo micro-MR is a technique able to detect the effects of cellulite and gender. This study can be extended for further investigations of drugs and/or medical devices for cellulite treatment.

Adipose Tissue↗
PubMed2003

Functional magnetic resonance imaging of the human brain based on signal enhancement by extravascular protons (SEEP fMRI).

Functional magnetic resonance imaging (fMRI) studies of the human brain were carried out at 3 Tesla to investigate an fMRI contrast mechanism that does not arise from the blood oxygen-level dependent (BOLD) effect. This contrast mechanism, signal enhancement by extravascular protons (SEEP), involves only proton-density changes and was recently demonstrated to contribute to fMRI signal changes in the spinal cord. In the present study it is hypothesized that SEEP fMRI can be used to identify areas of neuronal activity in the brain with as much sensitivity and precision as can be achieved with BOLD fMRI. A detailed analysis of the areas of activity, signal intensity time courses, and the contrast-to-noise ratio (CNR), is also presented and compared with the BOLD fMRI results. Experiments were carried out with subjects performing a simple finger-touching task, or observing an alternating checkerboard pattern. Data were acquired using a conventional BOLD fMRI method (gradient-echo (GE) EPI, TE = 30 ms), a conventional method with reduced BOLD sensitivity (GE-EPI, TE = 12 ms), and SEEP fMRI (spin-echo (SE) EPI, TE = 22 ms). The results of this study demonstrate that SEEP fMRI may provide better spatial localization of areas of neuronal activity, and a higher CNR than conventional BOLD fMRI, and has the added benefit of lower sensitivity to field inhomogeneities.

Brain↗
PubMed2002

Extravascular proton-density changes as a non-BOLD component of contrast in fMRI of the human spinal cord.

The fractional signal intensity change (Delta S/S) observed during activation in T(2)-weighted fMRI of the spinal cord has previously been shown to depend linearly on the echo time (TE) but to have a positive value of roughly 2.5% extrapolated to zero TE. In this study we investigated the origin of this finding by measuring the Delta S/S in spinal fMRI with very short TEs. Our results demonstrate that the Delta S/S does not approach zero, but has a value as high as 3.3% at TE = 11 ms. At TEs > 33 ms we observed the linear relationship between Delta S/S and TE as in previous studies. These data demonstrate that there is a non-BOLD contribution to signal changes observed in spinal fMRI. We hypothesize that this contribution is a local proton density increase due to increased water exudation from capillaries with increased blood flow during neuronal activation, and term this effect "signal enhancement by extravascular protons" (SEEP).

Humans↗
PubMed2002

Mapping of neuronal function in the healthy and injured human spinal cord with spinal fMRI.

Functional magnetic resonance imaging of the human spinal cord is carried out with a graded thermal stimulus in order to establish the relationship between signal changes and neural activity. Studies of the lumbar spinal cord in 15 healthy subjects with 10 degrees C stimulation of the skin overlying the calf demonstrate a pattern of activity that matches the neuronal anatomy of the spinal cord. This pattern shows primarily dorsal horn activity, with expected components of motor reflex activity as well. Moreover, a later response shifting to noxious cold over time is also demonstrated with a shift to more dorsal horn activity. Signal intensity changes detected at different degrees of thermal stimulation have a biphasic nature, with much larger signal changes below 15 degrees C as the stimulus becomes noxious, and agree well with electrophysiological results reported in the literature. These findings demonstrate a strong correspondence between Spinal fMRI results and neural activity in the human spinal cord. Spinal fMRI is also applied to studies of the injured spinal cord, below the site of injury. Results consistently demonstrate activity in the spinal cord even when the subjects cannot feel the stimulus being applied. Signal intensity changes demonstrate the same stimulus-response pattern as that in noninjured subjects, but the areas of activity in the spinal gray matter are notably altered. In subjects with complete injuries, activity is absent ipsilateral to the thermal stimulation, but appears to be enhanced on the contralateral side. These findings demonstrate the reliability of Spinal fMRI and its clinical potential.

Adult↗
PubMed2002

Functional magnetic resonance imaging of the human cervical spinal cord with stimulation of different sensory dermatomes.

Functional MR imaging (fMRI) of the cervical spinal cord was carried out in 13 healthy volunteers. A cold stimulus was applied, at different times, to three different sensory dermatome regions overlying the right hand and forearm: the thumb side of the palm, the little finger side of the palm, and the forearm below the elbow. Stimulation of these areas is expected to involve the 6(th), 8(th), and 5(th) cervical spinal cord segments respectively. Whereas true activations are expected to correspond to the region being stimulated, false activations such as arising from noise and motion, are not. The results demonstrate that clustering of active pixels into groups based on their intensity time courses discriminates false activations from true activations. Following clustering, the distribution of activity observed with fMRI matched the expected regions of neuronal activation with the different areas of stimulation on the hand and forearm.

Adult↗
PubMed2001

Spin-echo versus gradient-echo fMRI with short echo times.

Blood-oxygen level dependent signal changes in the visual cortex were investigated as a function of echo time with spin-echo and gradient-echo EPI at 1.5 T and 3 T. The linear relationship between the fractional signal change and the echo time was apparent in all cases. Relaxation rate changes determined from the slope of this linear relation agree with published values, intercept values extrapolated to an echo time of zero, however, were 0.66% to 1.0% with spin-echo EPI, and 0.11% to 0.35% with gradient-echo EPI. Spin-echo and gradient-echo EPI can therefore yield similar signal changes at sufficiently short echo times.

Echo-Planar Imaging↗
PubMed2001

Characterization of contrast changes in functional MRI of the human spinal cord at 1.5 T.

Contrast changes observed in functional magnetic resonance imaging in the human spinal cord were investigated with both motor and sensory tasks over a range of echo times. Data were acquired using a single-shot fast spin-echo sequence at 1.5 Tesla. Data were analyzed with two different correlation thresholds and the effects of altering the order of repeated experiments was also investigated. Plots of the fractional signal change as a function of echo time yielded linear functions with slopes corresponding to relaxation rate changes of -0.30 sec(-1) with sensory stimulation and approximately -0.50 sec(-1) with a motor task. However, the fractional signal change extrapolated to an echo time of zero was significantly greater than zero in each case and was roughly 2.5%. This suggests that in addition to the BOLD effect there is a baseline signal change which occurs concomitant to neuronal activation in the spinal cord.

Adult↗
PubMed2001

The effectiveness of Haemophilus influenzae type b conjugate vaccines in a high risk population measured using immunization register data.

The Northern Territory of Australia has had historically very high incidence rates of invasive Haemophilus influenzae type b disease in children less than 5 years of age, with the burden of disease greatest among Aboriginal infants less than 12 months. This study documents the impact of conjugate Hib vaccines introduced in 1993. Immunization rates were monitored using an existing immunization register, and case finding was done retrospectively using hospital and laboratory records. Following the vaccine introduction, the incidence fell abruptly to a seventh of its pre-vaccination level, in both Aboriginal and non-Aboriginal children. The effectiveness of PRP-OMPC (PedvaxHIB) was 97.5% and the overall effectiveness of the vaccination programme was 86.3%. The study shows Hib immunization as an effective intervention while discussing continuing needs for Hib control in high risk populations. It also illustrates the benefit of immunization registers in the evaluation of immunization programmes and assessment of vaccine effectiveness.

Bacterial Capsules↗
PubMed2001

Tuberculosis notifications in Australia, 1998.

Since the inception of the National Mycobacterial Surveillance System (NMSS) in 1991, annual crude notification rates for tuberculosis have remained stable at between 5 and 6 per 100,000 population. In 1998, there was a total of 923 TB notifications in Australia of which 884 were new TB cases, and 39 relapsed cases. The corresponding annual crude notification rate for new and relapsed TB was 4.72 and 0.21 per 100,000 respectively. Seventy-seven percent of notifications that had a country of birth reported were overseas born. In keeping with trends observed over recent reporting years, the populations for which notified TB rates are highest include the overseas born from high prevalence countries and Indigenous Australians. The lowest rates of disease have continued to be reported in the non-Indigenous, Australian born population. Surveillance reports over the last seven years indicate that the rate of disease in this population is gradually declining.

Adolescent↗
PubMed2001

Tuberculosis notifications in Australia, 1999.

Australia has one of the lowest incidence of tuberculosis in the world. The crude annual notification rate for tuberculosis (TB) has remained stable at between 5 and 6 per 100,000 population since 1991. In 1999, there were a total of 1,159 TB notifications in Australia of which 1,117 were new TB cases, and 42 were relapsed cases. The corresponding annual notification rate for new and relapsed TB was 5.9 and 0.2 per 100,000 population respectively. People born overseas accounted for 83 per cent of the notified cases. TB notification rates remain highest among overseas-born residents from high prevalence countries, and indigenous Australians. The lowest rates of disease are in the non-indigenous, Australian born population and data from the last 7 years indicate that the rate of tuberculosis in this population is continuing to fall.

Age Distribution↗
PubMed2000

Surveillance of pneumococcal disease in Australian states and territories.

Information on pneumococcal disease, including immunisation programs, and optimum future surveillance in each Australian State and Territory were discussed at the Pneumococcal Disease in Australia Workshop on 26-27 March 1999. Workshop participants further expanded on the surveillance aspects of the Workshop in this report. Most participants favoured notification by laboratories of pneumococcal isolates from sterile sites, to provide baseline surveillance data before immunisation programs are fully implemented. It was also thought that trends in antimicrobial resistance should be notified.

Australia↗
PubMed1999

Middle ear effusion: rate and risk factors in Australian children attending day care.

There have been no previous longitudinal studies of otitis media conducted in non-Aboriginal Australian children. This paper describes the rate and risk factors for middle ear effusion (MEE) in children attending day care in Darwin, Australia. A prospective cohort study of 252 children under 4 years was conducted in 9 day care centres over 12 fortnights between 24 March and 15 September 1997. Tympanometry was conducted fortnightly and multivariate analysis used to determine risk factors predicting MEE. The outcome of interest was the rate of type B tympanograms per child detected in either ear at fortnightly examinations. After adjusting for clustering by child, MEE was detected on average 4.4 times in 12 fortnights (37% of all examinations conducted). Risk factors associated with presence of effusion were younger age, a family history of ear infection, previous grommets (tympanostomy tubes), ethnicity and the day care centre attended. A history of wheeze appeared protective. These effects were modest (RR 0.57-1.70). Middle ear effusion is very common in children attending day care in Darwin. This has clinical importance, since MEE during early childhood may affect optimal hearing, learning and speech development. There is little scope for modification for many of the risk factors for MEE predicted by this model. Further study of the day care environment is warranted.

Child Day Care Centers↗
PubMed1999

Streptococcus pneumoniae antibiotic resistance in Northern Territory children in day care.

BACKGROUND: There is evidence that the rapid rise in Streptococcus pneumoniae (SP) antimicrobial resistance seen in other countries may have commenced in Australia. Streptococcus pneumoniae carriage and resistance levels are described for urban Northern Territory children in day care. METHODS: A prospective cohort study was conducted of 250 children in nine Darwin day care centres between 24 March and 15 September 1997. Each fortnight nasopharyngeal swabs were collected from children, and parents were interviewed about medications administered. RESULTS: Streptococcus pneumoniae was detected in 52% (1028/1974) of all nasopharyngeal swabs. Streptococcus pneumoniae was isolated from 92% (231/250) of children at some time. Penicillin resistance was found in 30% (312/1028) of isolates using a screening test. Of these, 256 (82%) had resistance confirmed by E-test. Two hundred and one (20% of all isolates) had intermediate penicillin resistance and 55 (5% of all isolates) had high level resistance. Ceftriaxone resistance was found in 19% of children's first isolates. Resistance to other antibiotics was also common: co-trimoxazole 45%, erythromycin 17%, tetracycline 17% and chloramphenicol 13%. A total of 17% (172/1028) of the isolates were multiresistant. The average fortnightly proportion of children given antibiotics was 16% (405/2476). CONCLUSION: Levels of intermediate and high level penicillin resistance in this day care population are consistent with previous data from the Northern Territory, and considerably higher than the rest of Australia. The national trend of increasing pencillin resistance is likely to continue.

Australia↗
PubMed1999

Evaluating the potential for opportunistic vaccination in a Northern Territory hospital.

OBJECTIVE: To evaluate the potential for opportunistic vaccination and a simple intervention aimed at improving vaccination coverage for children in hospital. METHODS: Hospital records were reviewed for children under 7 years, discharged from paediatric wards (PW) and the emergency department (ED) for 4 weeks before and after an intervention (423 and 446 children, respectively). This comprised the education of staff and the introduction of prompts to record vaccination status. RESULTS: Documentation of vaccination status increased in the PW (63-90%) and the ED (24-46%), as did the adequacy of detail recorded (51-77% and 8-36%, respectively). Opportunistic vaccination increased from zero of 84 opportunities during the first audit to six of 139 following the intervention. All but one vaccine was given in the PW. Opportunistic vaccination improved when documentation identified a need for vaccination (P = 0. 02). CONCLUSION: There were numerous missed opportunities to vaccinate children in hospital, especially in the ED. Simple prompts improved documentation of vaccination status and the detail of information recorded. Despite improved documentation, opportunistic vaccination failed to improve in the ED. Improving documentation of vaccination status is not sufficient in itself to improve opportunistic vaccination.

Bacterial Vaccines↗