Biomedical subjects

M Norris

Publications and source records attributed to M Norris.

At least 19 recordsLinked to original sources

PubMed2006

Uptake, metabolism, mutant frequencies and mutational spectra in lambda transgenic medaka embryos exposed to benzo[alpha]pyrene dosed sediments.

The goal of this study was to provide data supporting the use of lambda transgenic medaka (Oryzias latipes) embryos to evaluate mutagens in sediments. Embryos incubated directly on sediments dosed with the reference mutagen, benzo[alpha]pyrene (BaP), were examined for BaP uptake and metabolism. Mutant frequency and mutational spectrum were assessed in the cII transgene recovered from adult medaka livers exposed as embryos. Embryos rapidly accumulated 14C-BaP and metabolized BaP to polar metabolites, indicating sediment-sorbed BaP is available for bioaccumulation and medaka embryos are capable of bioactivating this mutagen. Exposure of embryos to BaP dosed sediments significantly induced cII transgene mutant frequencies with mutations predominantly being in G:C base pairs, consistent with known mechanisms of BaP mutagenesis in transgenic mice and fish.

Animals↗

PubMed2006

Does pulse lavage reduce hip hemiarthroplasty infection rates?

This paper reports a prospective randomized trial involving four hospitals in the south of England, in which every hemiarthroplasty (American Association of Anaesthetists grade IV and above) was randomized to one of two limbs. In the first group, the patients received a 2-L pulse lavage normal saline washout; in the second group, they received a 2-L normal saline washout via a jug or a syringe. All wounds were reviewed during their time in hospital up to 30 days post surgery or discharge (using criteria from the Nosocomial Infection National Surveillance Survey). Any re-admissions for infection were recorded. The pulse lavage group had a significantly lower total infection rate and, specifically, a decreased 'joint space' or deep infection rate.

Arthroplasty, Replacement, Hip↗

PubMed2006

Neuropsychological functioning and delusions in dementia: a pilot study.

The present pilot study investigated the pattern of neuropsychological functioning associated with the presence of delusions in mild-to-moderate dementia. Participants, all of whom met criteria for dementia, were divided into two groups, delusional (n = 9) and non-delusional (n = 9). Individuals with hallucinations were excluded. Participants completed a neuropsychological test battery. Global cognitive functioning (MMSE) and behavioral disturbance (BEHAVE-AD) were also assessed. Differences between the delusional and non-delusional group were most marked for immediate recall of stories, which was higher in the non-delusional group. Scores on semantic fluency, attention (mental control), and overall cognitive functioning (MMSE) were also lower in the delusional group. Conversely, simple attention span (Digit Span) was within normal limits in both groups. Floor effects were noted on measures of delayed recall and alternating attention. This study supports previous findings of greater neuropsychological impairment in delusional as compared to non-delusional individuals with dementia. However, some areas of cognitive functioning may be relatively preserved. Future research should examine semantic processing in persons with dementia with and without delusions.

Aged↗

PubMed2003

Radiographic measurement of joint space height in non-osteoarthritic tibiofemoral joints. A comparison of weight-bearing extension and 30 degrees flexion views.

There have been many reports which suggest that in patients with tibiofemoral osteoarthritis, a reduction in joint space is demonstrated better on weight-bearing radiographs taken with the knee in semiflexion than in full extension. The reduction has been attributed to the loss of articular cartilage in the contact area in a semiflexed arthritic knee. None of these studies have, however, included normal knees. We have therefore undertaken a prospective, double-blind, randomised study in order to evaluate the difference in the joint-space of arthroscopically-proven normal tibiofemoral joints as seen on weight-bearing full-extension and 30 degrees flexion posteroanterior radiographs. Twenty-two knees were evaluated and the results showed that there may be a difference of up to 2 mm in the two views. This difference could be attributed to the inherent differential thickness of the articular cartilage in different areas of the femoral and tibial condyles and a change in the areas of contact between them.

Adolescent↗

PubMed2002

A study of "white spotted kidneys" in cattle.

A study was performed at an abattoir in Australia, in an attempt to correlate focal chronic interstitial nephritis (FCIN) producing the so-called "white spotted kidney", with Leptospira spp. and other pathogens in cattle. Samples of kidneys, urine and blood were collected immediately after slaughter from 46 two-year-old heifers, and 72 cows and bulls with gross lesions consistent with FCIN. The same samples were also collected from nine heifers and 12 cows with no gross kidney lesions. Aqueous humour was also collected from the eye of 17 of the adult animals. The sera were processed by a microscopic agglutination test for leptospira antibodies, while all the other samples were cultured for Leptospira spp. and also processed for routine aerobic and anaerobic culture for other pathogens. Sub-samples from all the kidneys were fixed in 10% buffered formalin and processed histologically. Antibody titers of 1:400 or higher for Lepstospira borgpeterseni serovar hardjo were found in six adult animals with FCIN and in one adult animal with no gross kidney changes, while antibody titers of 1:400 to L. borgpeterseni serovar tarassovi were found in only one animal with FCIN. L. borgpeterseni serovar hardjo was isolated from the urine and kidney of one adult animal and from the urine of another adult animal, both with FCIN. No pathogens were isolated from any of the other samples. The histological lesions were consistent in most cases with FCIN. The results suggest that neither Leptospira spp. nor active infection by other bacteria are associated with the so-called "white spotted kidneys".

Abattoirs↗

PubMed2001

An assessment of the feasibility of using image analysis in the oyster embryo-larval development test.

In this study the feasibility of using the latest image capture, processing, and analysis techniques in the oyster embryo-larval development (OEL) test was assessed. This initially involved determining whether the OEL test could be carried out in multiwell plates (which would assist in the application of the image analysis technique), based on data from tests with the reference toxicant zinc and industrial effluents. The study then ascertained which of the 31 image analysis parameters of the Image Pro Plus software used was most appropriate for differentiating between the D larvae and non-D larvae at the end of the test procedure in a manner similar to that of visual observations. On the basis of the zinc reference toxicant and effluent test data derived in this study, the OEL test can be effectively carried out in 24 chamber multiwell plates, which provides the opportunity to count objects with image analysis software. The use of the image analysis parameters area and size (length) in combination resulted in mean control abnormalities and EC50 values in zinc reference toxicant tests which were not significantly different statistically from corresponding values derived using visual observations. Discrimination using the area and length parameters may be improved by the inclusion of other parameters in a suite of measurements which would reduce interference from extraneous material or lighting artefacts. Furthermore, the use of multiwell plates and image analysis can eliminate the variability associated with sub-sampling and inter-operator differences in the counts of D larvae and non-D larvae which is evident with the current visual observation method.

Animals↗

PubMed2001

Bacteriophage lambda and plasmid pUR288 transgenic fish models for detecting in vivo mutations.

We adapted transgenic rodent mutation assays based on fish carrying bacteriophage lambda and plasmid pUR288 vectors to address the needs for improved methods to assess health risks from exposure to environmental mutagens and also to establish new animal models to study in vivo mutagenesis. The approach entails separating the vectors from fish genomic DNA and then shuttling them into specialized strains of E. coli bacteria to analyze spontaneous and induced mutations in either lacI and cII or lacZ mutational targets. Fish exhibited low frequencies of spontaneous mutants comparable to the sensitivity of transgenic rodent models. Mutations detected after treating fish with chemical mutagens showed concentration-dependent, tissue-specific, and time-dependent relationships. Spontaneous and induced mutational spectra also were consistent with the specificity of known mutagens, further supporting the utility of transgenic fish for studies of in vivo mutagenesis.

Journal Article↗

PubMed2001

Single nucleotide polymorphisms in the human reduced folate carrier: characterization of a high-frequency G/A variant at position 80 and transport properties of the His(27) and Arg(27) carriers.

The presence of sequence variants in the human reduced folate carrier (hRFC) was assessed in leukemia blasts from children with acute lymphoblastic leukemia (ALL) and in normal peripheral blood specimens. A CATG frame shift insertion at position 191 was detected in 10-60% of hRFC transcripts from 10 of 16 ALL specimens, by RFLP analysis and direct sequencing of hRFC cDNAs. In genomic DNAs prepared from 105 leukemia (n = 54) and non-leukemia (n = 51) specimens, PCR amplifications and direct sequencing of exon 3 identified a high-frequency G to A single nucleotide polymorphism at position 80 that resulted in a change of arginine-27 to histidine-27. The allelic frequencies of G/A80 were nearly identical for the non-leukemia (42.2% CGC and 57.8% CAC) and leukemia (40.7% CGC and 59.3% CAC) genomic DNAs. In cDNAs prepared from 10 of these ALL patients, identical allelic frequencies (40 and 60%, respectively) were recorded. In up to 62 genomic DNAs, hRFC-coding exons 4-7 were PCR-amplified and sequenced. A high-abundance C/T696 polymorphism was detected with nearly identical frequencies for both alleles, and a heterozygous C/A1242 sequence variant was identified in two ALL specimens. Both C/T696 and C/A1242 were phenotypically silent. In transport assays with [(3)H]methotrexate and [(3)H]5-formyl tetrahydrofolate, nearly identical uptake rates were measured for the arginine-27- and histidine-27-hRFC proteins expressed in transport-impaired K562 cells. Although there were no significant differences between the kinetic parameters for methotrexate transport for the hRFC forms, minor (approximately 2-fold) differences were measured in the K(i)s for other substrates including Tomudex, 5,10-dideazatetrahydrofolate, GW1843U89, and 10-ethyl-10-deazaaminopterin and for 5-formyl tetrahydrofolate.

Amino Acid Substitution↗

PubMed2000

Age-related differences in the frequency of personality disorders among inpatient veterans.

This cross-sectional study explored age-related differences in the frequency of diagnosis of personality disorder (PD) among 790 veterans admitted to a psychiatric inpatient unit across three age groups: 20-39, 40-59, and 60+. Older adults obtained a lower frequency (55.4%) of PD diagnosis than middle-aged adults (69.0%), who in turn obtained a lower frequency of PD diagnosis than young adults (75.9%). Older adults and middle-aged adults were less likely to receive a diagnosis of Borderline PD than young adults. Older adults were also less likely to receive a diagnosis of Mixed PD than young adults, but received significantly more diagnoses of Narcissistic PD than young adults. Patients diagnosed with PD had higher rates of psychiatric hospitalization than those with no diagnosis of PD. Older adults and middle-aged adults with PD had significantly fewer psychiatric hospitalizations than young adults with PD, whereas there were no age-related differences in the frequency of medical hospitalizations. These findings are consistent with research suggesting an overall softening of PD features with age, particularly those characteristic of the 'dramatic-erratic', Cluster B types.

Adult↗

PubMed2000

Lai-like leptospira from the Andaman Islands.

BACKGROUND & OBJECTIVES: Leptospirosis has been an important public health problem in the Andaman Islands since 1988. As information about the exact etiological agent is not available, the present study was undertaken to isolate and identify Leptospira from human patients. METHODS: An isolate coded AF61 was recovered from the blood of a patient clinically suspected to have leptospirosis, with fever, headache and body aches as the main symptoms. The isolation was done using Ellinghausen-McCullough-Johnson-Harris (EMJH) medium following standard procedure. The isolate was identified using microscopic agglutination test (MAT) with 'groupsera', cross agglutination absorption test (CAAT) and monoclonal antibodies. RESULTS: Agglutination tests with rabbit antisera revealed that the isolate belonged to the serogroup icterohaemorrhagiae. The CAAT results showed that it was closely related to the serovar lai. Analysis of AF61 with monoclonal antibodies confirms our observation with CAAT that it is closely related to the reference strain Lai serovar lai. INTERPRETATION & CONCLUSIONS: Serovar lai, has been associated with pulmonary haemorrhage in China and Korea. However, the strain AF61 was not isolated from a patient with pulmonary symptoms. Further studies are needed to understand the possible relationship between serovars and clinical patterns and the distribution of serovar lai and lai-like strains in Asia.

Australia↗

PubMed1999

Hepatitis B vaccination of personnel employed in Victorian hospitals: are those at risk adequately protected?

OBJECTIVE: To examine the policies and practices in hospitals within the state of Victoria, Australia, with respect to vaccination of staff against hepatitis B infection. DESIGN: A written self-administered questionnaire to be completed by the infection control officer (or designated officer for hepatitis B vaccination) within each hospital. SETTING: Public (teaching and nonteaching) and private hospitals, including metropolitan and rural institutions in Victoria. PARTICIPANTS: A random sample of 30% of Victorian hospitals were asked to participate in the survey. Of 78 eligible institutions, 69 (88%) completed and returned questionnaires. RESULTS: There was no consistent hepatitis B prevention policy in place across Victoria. Of the 69 responding hospitals, 63 (91%) offered hepatitis B vaccination to staff, and 58 (84%) of these also paid all costs of vaccination. Of the 63 hospitals offering vaccination to staff, 39 offered vaccination to all staff, 23 offered vaccination based on job title, and one offered vaccination based on anticipated exposure. In many institutions, postexposure protocols were recalled more readily than preexposure vaccination guidelines. Numerous respondents indicated a need for clear guidelines on policy and clarification on practical matters of management, such as acceptable immune levels, management of nonresponders to the primary series, and the need for, and timing of, booster doses of vaccine. Eleven (18%) of the 63 hospitals offering hepatitis B vaccination to staff undertook routine prevaccination screening, a practice not generally regarded as cost-effective in Australia. Fifty-five of these hospitals (91%) also undertook postvaccination screening. CONCLUSIONS: It is evident from this study that a considerable number of potentially susceptible healthcare personnel in Victorian hospitals remain unprotected against hepatitis B infection. A more reliable and consistent approach to preexposure hepatitis B vaccination is recommended.

Adult↗

PubMed1998

Decline in rates of seropositivity for measles, mumps, and rubella antibodies among previously immunized children treated for acute leukemia.

We prospectively determined the measles-mumps-rubella (MMR) antibody status of 39 previously vaccinated children before and after administering protocol-directed chemotherapy for acute leukemia. At diagnosis the seropositivity rates for measles and mumps-specific immunoglobulin G were > or = 90%, while the seropositivity rate for rubella was 85%. After treatment, rates of seropositivity for measles antibody declined by 13% (90% of patients to 77%; P = .13); for mumps antibody, by 18% (97%-79%; P = .02); and for rubella antibody, by 21% (85%-64%; P = .03). These findings suggest that some survivors of acute leukemia during childhood have an increased susceptibility to MMR viruses and would benefit from posttreatment evaluation of their immune statuses and from possible revaccination.

Acute Disease↗

PubMed1997

Review of leptospirosis notifications in Queensland 1985 to 1996.

To provide an overview of leptospirosis in Queensland, the World Health Organization/Food and Agriculture Organization Collaborating Centre for Reference and Research on Leptospirosis undertook a study of notifications of the disease from 1985 to 1996. The review encompassed information drawn from notifications to Queensland Health and questionnaires sent to doctors. Notifications were highest between February and July and the highest population rates were identified in the Central West and Peninsula Health Regions. Ninety-one per cent of notifications were for males. At risk population groups included meat workers, those working with farm animals and banana workers. The study found the incidence of leptospirosis was higher in 1996 than in previous years. Improved diagnosis and surveillance will aid our understanding of the preventable risk factors for leptospirosis, especially in geographic areas not considered at high risk and in groups not in occupations traditionally linked to the disease.

Abattoirs↗

PubMed1997

MR imaging of rotator cuff tendon tears: comparison of T2*-weighted gradient-echo and conventional dual-echo sequences.

OBJECTIVE: Although MR imaging evaluation of the rotator cuff is usually done with proton density- and T2-weighted spin-echo techniques, interest also exists in T2*-weighted gradient-recalled echo techniques. The shorter scan times of T2*-weighted sequences can be used to increase the number of signal averages and thus improve the signal-to-noise ratio. Our purpose in this study was to compare the sensitivity and specificity of oblique coronal T2*-weighted MR image interpretations with conventional dual-echo T2-weighted MR image interpretations when diagnosing rotator cuff tears. SUBJECTS AND METHODS: Forty-seven consecutive patients who underwent both MR imaging and shoulder arthroscopy were included in this study. The MR examination included both a 7 min 20 sec acquisition time proton density- and T2-weighted oblique coronal sequence and a 7 min 5 sec T2*-weighted oblique coronal sequence. The oblique coronal dual-echo T2-weighted images were evaluated by two of the authors independently, who were unaware of the arthroscopic findings. Each of the two observers graded each cuff as being intact, having a partial-thickness tear, or having a full-thickness tear. After a 3-week interval, each of the two observers then interpreted the T2*-weighted oblique coronal MR images in the same manner. Sensitivity and specificity for the two sets of interpretations were calculated in terms of the ability of the observers to use the two sequences to distinguish an intact cuff from a rotator cuff tear and to distinguish a partial-thickness cuff tear from an intact cuff or full-thickness tear. The results were then compared using Student's t test calculations. RESULTS: For distinguishing an intact cuff from a torn cuff, the sensitivity of the observers' interpretations was lower for the T2*-weighted images than for the conventional dual-echo T2-weighted images. The specificity also decreased with interpretation of the T2*-weighted images for one observer and was unchanged for the second observer. For distinguishing a partial-thickness cuff tear from a non-partial-thickness cuff tear (intact or full-thickness tear), the sensitivity and specificity of both observers decreased with interpretations of the T2*-weighted images when compared with the conventional dual-echo T2-weighted images. The results did not reach statistical significance. CONCLUSION: In this small study evaluating the ability of observers to diagnose rotator cuff tears on oblique coronal MR images only, interpretations of T2*-weighted images tended to be less sensitive and specific than interpretations of standard dual-echo T2-weighted images.

Adult↗

PubMed1996

Minimal change glomerulonephritis in a 90-year-old patient: what is the ideal approach?

We report the case of a 90-year-old lady who presented with full-blown nephrotic syndrome. Percutaneous renal biopsy allowed us to confirm the diagnosis of minimal change glomerulopathy; she entered a 2-year period of remission after a 6-month course of prednisone (starting dose 1.5 mg/kg). The patient sustained minor effects of both renal biopsy and corticotherapy. Percutaneous renal biopsy is justified in the very elderly because the risk of mortality and morbidity related to corticotherapy outweigh the risk related to percutaneous renal biopsy, providing high-risk patients are excluded, such as amyloidosis or abnormal coagulation or uncontrolled arterial hypertension.

Aged↗

PubMed1995

Bucket-handle tears of the medial and lateral menisci of the knee: value of MR imaging in detecting displaced fragments.

OBJECTIVE: A bucket-handle tear of a meniscus is a longitudinal tear with an attached fragment displaced away from the meniscus. Several MR findings of bucket-handle tears have been reported previously. However, the sensitivity of MR for detecting the displaced fragment is unknown. We determined the sensitivity of MR for detecting a displaced bucket-handle tear and determined how the sensitivity varied with tears of different sizes. We also evaluated whether the three findings of a displaced fragment differed in frequency between medial and lateral tears. MATERIALS AND METHODS: We retrospectively evaluated the MR examinations of 39 patients with arthroscopically proven bucket-handle tears for signs of a displaced meniscal fragment. Thirty-two patients had medial meniscal bucket-handle tears, and seven had lateral tears. Two observers evaluated each examination independently, with discrepancies resolved by consensus of a third reader. Each observer evaluated for three findings of a bucket-handle tear: a double posterior cruciate ligament sign, a flipped meniscus sign, or a fragment in the intercondylar notch. A double posterior cruciate ligament sign is present when the meniscal fragment is displaced anterior to the posterior cruciate ligament, resembling two ligaments. A flipped meniscus sign occurs when the fragment is flipped anteriorly so the anterior horn of the meniscus appears to be enlarged. We tested for differences between menisci in the sensitivity for each sign using Pearson's chi-squared test or Fisher's exact test. We compared the sensitivity of MR for identifying fragments when the tear involved one third, two thirds, or the entire meniscus using Spearman's rank correlation. RESULTS: Overall sensitivity for a displaced fragment was only 0.64. When the bucket-handle tear involved the entire meniscus, the displaced fragment could be seen in 84% of the menisci. The double posterior cruciate ligament sign was seen in 53% of the medial and none of the lateral bucket-handle tears (p = .01). The flipped meniscus sign was noted in 44% of medial and 29% of lateral menisci (p = .68), and a fragment was identified in the intercondylar notch in 66% of medial and 43% of lateral menisci (p = .40). CONCLUSION: MR is sensitive for detecting meniscal fragments in large bucket-handle tears, but is less so in small tears. The flipped meniscus sign and presence of a fragment in the notch were comparably useful findings of a displaced fragment in both medial and lateral menisci. The double posterior cruciate ligament sign was noted only in medial bucket-handle tears.

Adult↗

PubMed1994

Late surgical complications of choledochal cystoenterostomy.

Choledochal cyst is a rare congenital abnormality of the biliary tract characterized by dilatation and stasis. Cyst excision is now preferred to internal drainage because of the predilection for development of cancer in the unresected cyst wall. We report on four patients who required reoperations for complications of prior cystoenteric drainage from 14 to 21 years after the original operations. Gastrointestinal bleeding from cyst ulceration as occurred in one patient is heretofore unreported. This reoperative experience emphasizes the importance of cyst excision as primary therapy and underscores these principles: 1) The spectrum of complications, including infection, pancreatitis, cancer, and bleeding may occur with or without intracyst and ductal stones; 2) Radical operative procedures may be required for treatment of the complications; 3) Despite these, cholangiocarcinoma has a dismal prognosis; 4) Patients whose cysts remain unexcised require meticulous lifelong scrutiny and strong consideration for planned reoperation at the time of the first complication.

Adult↗

PubMed1993

Direct BRLF1 binding is required for cooperative BZLF1/BRLF1 activation of the Epstein-Barr virus early promoter, BMRF1.

Disruption of Epstein-Barr virus (EBV) latency is mediated through the activation of the viral immediate-early proteins, BZLF1 (Z) and BRLF1 (R).i.; (Chevallier-Greco, A., et al., (1986) EMBO J., 5, 3243-9; Countryman, and Miller, G. (1985) Proc. Natl. Acad. Sci. USA, 82, 4085-4089). We have previously demonstrated that these proteins cooperatively activate the EBV early promoter BMRF1 in lymphoid cells but not in epithelial cells. Although cooperative transactivation by these proteins has been demonstrated with a number of EBV promoters, the mechanism of this interaction is not well understood. We now show that the cooperative activation of the BMRF1 promoter by Z-plus-R requires an intact R binding site and at least one functional Z response element (ZRE). Despite the presence of an R binding site, the BMRF1 promoter is only moderately responsive to R alone in either HeLa or Jurkat cells. Efficient activation of the BMRF1 promoter by Z alone in HeLa cells requires two ZREs (located at -59 and -106), whereas two additional Z binding sites (located at -42 and -170) contribute very little to Z-induced activation. In the absence of ZREs, Z acted as a repressor of R-induced transactivation. These observations, along with observations made by other investigators (Giot, J.F. et al., (1991) Nucleic Acids Res., 19, 1251-8), suggest that Z-plus-R cooperative activation is dependent upon 1) direct binding by R and Z to responsive promoter elements and 2) contributions by cell-specific factors.

Base Sequence↗