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Biomedical subjects

L Burnett

Publications and source records attributed to L Burnett.

At least 55 records · Page 3Linked to original sources
PubMed1986

Relationship between hepatitis B virus DNA in blood and serological markers of hepatitis B infection.

The hepatitis B virus (HBV) DNA dot-hybridization assay has been introduced into clinical practice in Australia and its behaviour compared with that of the classic markers of HBV infection. A good correlation exists between the presence of HBV DNA and that of hepatitis B e antigen but the degree of dissociation between HBV DNA and the e:anti-e system was smaller than earlier studies would suggest. Patients who are seronegative for hepatitis B surface antigen (HBsAg), whether they possess anti-HBs, anti-HBc HBc (antibody to the core antigen), or neither antibody, gave uniformly negative results for the presence of HBV DNA. Theses results are different from those that were obtained from earlier studies of patients with chronic liver disease.

Acute Disease↗
PubMed1986

Development of a superior strategy for computer-assisted nucleotide sequence analysis.

A new strategy for high-resolution nucleotide sequence analysis has been developed. The strategy involves an exhaustive tree-searching algorithm which examines all possible combinations of short regions of sequence alignments, followed by culling of unsuitable sequence relationships. The new algorithm can detect sequence homologies invisible to existing algorithms, and is capable of detecting all possible sequence relationships.

Base Sequence↗
PubMed1986

Differential co-expression of alpha-actin genes within the human heart.

Human cardiac muscle has been studied to determine whether the ratio of cardiac alpha-actin to skeletal alpha-actin varies between the different chambers of the human heart taken from a single individual. Using mRNA dot-blots, and DNA probes specific for the cardiac and skeletal alpha-actin isotypes, we have found that both cardiac and skeletal alpha-actin mRNAs are present and co-expressed throughout the human heart. The pattern of alpha-actin co-expression in the left and right ventricles and in the interventricular septum is approximately the same, with cardiac alpha-actin being the dominant isotype (approx. 80% of total). However, the left atrium has a different relative composition of the two actins, with an even higher level of cardiac alpha-actin expression (95% of total).

Actins↗
PubMed1986

False-positive results with hepatitis B virus DNA dot-hybridization in hepatitis B surface antigen-negative specimens.

Three serum samples derived from healthy hepatitis B surface antigen-negative subjects were found to be reactive for hepatitis B virus (HBV) DNA sequences when assayed by DNA dot-hybridization. All three results were shown to be due to the presence of sequences which reacted with residual bacterial plasmid vector sequences in the DNA probe, and no evidence of HBV markers was demonstrated in the sera. This is the first report of a false-positive result with the HBV DNA dot-hybridization assay.

Adult↗
PubMed1986

Are specimens with "at risk" biochemical profiles more likely to be infectious for hepatitis B virus?

The potential infectivity of 640 plasma specimens with various biochemical profiles was directly assessed by hepatitis B virus (HBV) DNA dot-hybridization. We found that specimens with "at risk" biochemical profiles typical of various forms of liver disease were not significantly more likely to carry HBV than the general patient population. Specimens containing HBV cannot be distinguished from non-infectious specimens by any simple biochemical tests, including aminotransferases and bilirubin. The only predictive feature of HBV-positive samples was that they were more likely to be labeled as "biohazardous" by the medical staff, but even this was not always the case.

DNA, Viral↗
PubMed1985

An exhaustive tree-searching algorithm for high-resolution computer-assisted nucleotide sequence analysis.

A new computer search strategy has been devised for high-resolution nucleotide sequence analysis. The strategy differs from those used by earlier sequence analysing programs in that it is exhaustive and capable of detecting all possible homologies and other types of relationships between or within sequences irrespective of the pattern of matches and mismatches encountered. The implementation of this strategy into a working algorithm is described.

Algorithms↗
PubMed1985

The SEQANAL and SEQTALK programs: a new method of access to high-resolution nucleotide sequence comparison and analysis programs from a remote laboratory mini- or microcomputer.

A new method of access has been devised for biologists requiring the use of computer programs offering high-resolution analysis and comparison of nucleotide sequence data. The strategy involves the development of a pair of computer programs, called SEQANAL and SEQTALK, designed to operate in tandem. SEQANAL is a large and complex program intended to be used to discover regions of internal repeats and dyad symmetries within one sequence, or regions of homology, complementarity or optimal alignment between two sequences. Three algorithms are supported: those of Staden (1977, 1978); of Korn et al. (1977); Queen and Korn (1980); and the newly-described exhaustive tree-searching algorithm of Burnett et al. (1985, 1986). The SEQTALK program is a small, portable, interactive, front-end program with which the user can specify the instructions to control the SEQANAL program. Together, the SEQANAL and SEQTALK programs permit analyses to be performed at a remote facility on a mainframe computer under the complete control of a distant user equipped with minimal computing facilities, and without needing networking facilities.

Algorithms↗
PubMed1985

Risk factors associated with hepatitis B infection in antenatal patients.

Risk factors associated with HBsAg carriers were prospectively examined in 1821 women attending the Antenatal Clinic of an inner-city obstetrics hospital. Of the sample, 3.2% were HBsAg carriers and 28.7% of 725 tested for anti-HBs were positive. Birth in a country where the prevalence of HBsAg is high and Aboriginal ancestry were the major associated factors rather than a past history of hepatitis or intravenous drug use. Women from Indochina or the Pacific region, if HBsAg-positive, were more likely than other carriers to have markers of viral replication including HBeAg, hepatitis B virus (HBV) DNA, and DNA polymerase. Evidence of past infection with HBV also varied with country of birth, but 11% of women with no apparent risk factors for prior HBV infection were anti-HBs positive. This study indicates the need for a screening programme for HBsAg in antenatal populations.

Australia↗
PubMed1985

Can potentially infectious specimens containing hepatitis B virus be identified on the basis of their biochemical profile?

The potential infectivity of 1129 randomly selected plasma specimens was directly assayed by hepatitis B virus (HBV) DNA dot-hybridization. Presence or absence of HBV was then correlated with a biochemical profile of 20 common analytes obtained on these same specimens. We found that potentially infectious specimens could not be identified on the basis of any combination of simple biochemical tests; indeed, the infectious specimens were more "normal" in some tests of liver function than were the non-infectious specimens.

Blood Specimen Collection↗
PubMed1981

Percutaneous pelvic lymph node aspiration in carcinoma of the prostate.

We report on 121 patients with adenocarcinoma of the prostate who underwent lymphangiography and, when indicated, subsequent fine needle aspiration biopsy of lymph nodes. The clinical staging correlation with this procedure reveals an assumed falsely negative rate of 5 to 15 per cent. The falsely positive rate is 0. This procedure is essentially without morbidity and has allowed us to stage more confidently prostatic cancer and make appropriate therapeutic recommendations.

Adenocarcinoma↗
PubMed1981

Advanced ovarian cancer: brief intensive combination chemotherapy and second-look operation.

The effects of brief intensive combination chemotherapy have been evaluated in 59 patients with advanced epithelial ovarian cancer. Following surgery and before chemotherapy, 16 patients had limited residual cancer (tumor nodules 3 cm or less in diameter) and 43 had bulky disease (tumor nodules greater than 3 cm). Chemotherapy with hexamethylmelamine, cyclophosphamide or 5-fluorouracil, doxorubicin, and cisplatin was given intensively. Myelo-suppression was the most serious side effect, although gastrointestinal, neurologic, and renal toxicity was also observed. Fifty-five of the 58 (95%) evaluable patients had either a partial clinical response or no clinically detectable tumor following therapy. Forty-five of these 55 patients underwent a second-look surgical evaluation at 6 months; 17 of 45 patients (14 of 16 patients with limited residual disease and 3 of 29 with bulky disease) had no evidence of residual cancer, and 9 patients had all known cancer resected. Sixteen of 17 patients who attained a complete response as judged by laparotomy remain in remission; median follow-up has been 19 months (range, 9 to 30 months) following chemotherapy. This combination chemotherapy produces marked tumor regression as judged by second-look evaluation, and most patients who had limited residual disease have all evidence of cancer eradicated. Longer observations is required to determine how many of these patients will remain continuously free of ovarian cancer.

Adult↗
PubMed1979

Endometrial cancer and estrogen use. Report of a large case-control study.

Our case-control study of the relation between estrogen use and endometrial cancer involved 451 cases and 888 controls. The overall risk of endometrial carcinoma was sixfold for estrogen users as compared with nonusers; long-term users (greater than five years) had a 15-fold risk. Excess risk was present for both diethylstilberstrol and conjugated estrogens. The risk associated with cyclic use was as great as that for continuous use. Increased risk was associated with estrogen use for all histologic grades of the tumor. The risk of advanced-stage carcinoma was fourfold for estrogen users, but rhe confidence interval was wide, and this question requires further study. Finally, this investigation contradicts the speculation that the association between this cancer and estrogen use can be explained by swifter diagnosis for estrogen users, misclassification of estrogen-related hyperplasia or treatment of early symptoms of the tumor with estrogen.

Clinical Trials as Topic↗