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Biomedical subjects

J Burke

Publications and source records attributed to J Burke.

At least 19 recordsLinked to original sources
PubMed1992

The transmembrane and flanking sequences of beta 1,2-N-acetylglucosaminyltransferase I specify medial-Golgi localization.

UDP-GlcNAc:alpha 3-D-mannoside beta 1,2-N-acetylglucosaminyltransferase I (GnTI) is an N(in)/C(out) (type II) membrane protein, localized in the medial-Golgi, that initiates the conversion of high mannose N-glycans to complex N-glycans. Anti-rabbit GnTI antibodies were generated using a purified, enzymatically active, bacterial recombinant fusion protein as immunogen. Rabbit GnTI was effectively retained in the Golgi complex of transfected COS-1 cells and murine L cells, as assessed by indirect immunofluorescence using the species-specific anti-GnTI antibodies; no surface expression of rabbit GnTI could be detected in the transfected cells. Rabbit GnTI, stably expressed in murine L cells, was localized by immunoperoxidase electron microscopy to the medial-cisternae of the Golgi stack. The role of the transmembrane domain of GnTI in Golgi localization was examined by generation of a hybrid construct containing the amino-terminal 31 amino acids of GnTI, corresponding to the 25-residue transmembrane (signal/anchor) domain and flanking hydrophilic sequences, fused with ovalbumin; this ovalbumin/GnTI hybrid molecule was retained in the Golgi complex of transfected COS cells and stably transfected murine L cells. No surface expression of ovalbumin/GnTI was detected. In contrast, ovalbumin fused to the equivalent domains of the human transferrin receptor, a type II cell-surface protein, was efficiently expressed on the cell surface of transfected cells. The ovalbumin/GnTI hybrid molecules in the transfected L cells were N-glycosylated, indicating an N(in)/C(out) membrane orientation, and were localized by immunoperoxidase electron microscopy to one or two cisternae of the medial-Golgi (90% of stained Golgi profiles showed medial-cisternae staining). These results show that a signal contained within the transmembrane domain and flanking residues of GnTI specifies medial-Golgi localization.

Amino Acid Sequence↗
PubMed1992

Prevention of acute postoperative pressure rises in glaucoma patients undergoing cataract extraction with posterior chamber lens implant.

Acute elevations in intraocular pressure (IOP) commonly follow extracapsular cataract extraction and lens implant in glaucoma patients. Thirty six patients with glaucoma undergoing cataract extraction and posterior chamber lens implantation received one of three treatments. Group 1: 500 mg of Diamox Sustets (acetazolamide) 1 hour preoperatively (10 patients); Group 2: peroperative intracameral Miochol (acetylcholine) (11 patients); Group 3: the above treatments combined (15 patients). IOPs were measured at 3, 6, 9, and 24 hours postoperatively. The average of the maximum pressure rises above the preoperative level over the 24 hour period was greatest for the group receiving acetazolamide only at 8.9 mm Hg; for the acetylcholine group the average maximum rise was 6.3 mm Hg; while the combined treatment group showed a decrease of 0.7 mm Hg. IOP rises of > 6 mm Hg were seen in 7% of patients (one of 15) in the combined treatment group, 45% (five of 11) of the acetylcholine group, and 70% (seven of 10) of the acetazolamide group. IOP rises of > 10 mm Hg were seen in 7% of the combined treatment group, in 18% of the acetylcholine only group, and in 50% of the acetazolamide only group. A pressure rise > 20 mm Hg was seen in one patient receiving acetazolamide only and one patient receiving acetylcholine only. The difference between the acetylcholine group and the combined group for rises > 6 mm Hg was significant using the chi 2 test while the acetazolamide group showed a significant difference for rises > 6 and 10 mm Hg compared with the combined group. All acute pressure rises were recorded before or at 9 hours following operation except in the combined treatment patient where the rise occurred at 24 hours. To prevent the acute IOP rises seen following cataract surgery with lens implant in glaucoma patients we recommend combined ocular hypotensive therapy.

Acetazolamide↗
PubMed1992

Patients with suspected myocardial infarction: effect of mode of referral on admission time to a coronary care unit.

The aim of this prospective study was to determine the delay between the onset of symptoms and arrival in the coronary care unit of patients with suspected acute myocardial infarction, and the relative contribution to the total delay of patient delay, method of referral (self referral or general practitioner referral) and delay in the hospital before reaching the coronary care unit. All patients admitted with chest pain to the coronary care unit at Dudley Road Hospital, Birmingham, over the six month period April-September 1989 were included in the study. Ninety five patients were referred by their general practitioner and 107 patients attended the accident and emergency department directly or arrived by ambulance without contacting their general practitioner. The proportion of self referred and general practitioner referred patients with acute myocardial infarction, angina and non-cardiac chest pain were not significantly different. The total delay was significantly longer for patients who had been referred by their general practitioner (median 5.3 hours) than for self referrals (3.2 hours, P less than 0.001), with a significantly higher proportion of self referrals arriving at the coronary care unit within six hours of the onset of symptoms (77% versus 54%, P less than 0.01). Among general practitioner referrals, initial patient delay accounted for a median of 2.5 hours and the general practitioner's response time for a median of 1.1 hours. The delay in hospital was similar for both groups of patients. In inner city areas, self referral may result in considerably less delay than general practitioner referral allowing a greater proportion of patients to receive effective thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Care Units↗
PubMed1992

Effects of two types of head coverings in the rewarming of patients after coronary artery bypass graft surgery.

In this experimental study we examined the effects of two types of head coverings in the rewarming of patients who have had coronary artery bypass graft surgery during the initial 8-hour postoperative period. A third group with no head coverings served as a control. Eighty-one patients were randomly assigned to one of the three treatment groups; rectal temperatures were recorded on admission and hourly for the next 8 hours. An analysis of variance between the three groups revealed no statistically significant differences (p less than 0.05) in the length of time for patients to reach normothermia and in the net temperature gain achieved. Irrespective of the groupings, however, patients who took 5 hours or less to reach normothermia exhibited statistically significant differences (p less than 0.05) compared with patients who took longer: the former patients tended to be younger, the lowest induced operating room temperature tended to be higher, their admission temperatures tended to be higher, and minutes of cardiopulmonary bypass tended to be fewer.

Analysis of Variance↗
PubMed1991

In vivo fungal presence and growth on two resilient denture liners.

To determine whether two intraoral-setting resilient denture liners supported the in vivo presence or growth of oral commensal fungi, the liners were randomly placed in the mandibular complete dentures of 14 patients. Cytologic smears were made from the liner surfaces at 1 hour and 1, 2, 7, 14 and 30 days after intraoral placement. Yeast forms were observed in six patient trials of material A and in two trials of material B. Hyphae were observed in only one patient trial of material A and in two trials of material B. When yeast forms and hyphae findings were combined and were considered as indicative of fungal presence or growth, the prevalence up to 30 days was seven for material A and four for material B. Statistical analysis revealed no significant difference in the prevalence of fungal presence or growth between the two resilient denture liners tested.

Acrylic Resins↗
PubMed1991

The herpes simplex virus type 1 thymidine kinase is expressed in the testes of transgenic mice under the control of a cryptic promoter.

We reported previously that the herpes simplex virus type 1 (HSV-1) thymidine kinase reporter gene (tk) was expressed in the testes of transgenic mice when coupled to the promoter of a liver-specific mouse major urinary protein (MUP) gene. Here we show that HSV-1 tk is also expressed in the testis when coupled to a MUP pseudogene promoter, to a truncated MUP promoter that is not active in the liver, and to the promoter of the bovine thyroglobulin gene. Furthermore, HSV-1 tk itself was expressed in the testis, although its normal expression had been disabled by removing an upstream regulator of transcription. In every case, the same multiple transcripts were observed, with their 5' ends located downstream of the normal HSV-1 tk translation initiation codon. We conclude that the transcription of HSV-1 tk in the testis is directed by a cryptic TATA box-independent promoter located in the coding region of the gene. The longest HSV-1 thymidine kinase (TK) polypeptides synthesized in the testis were shorter than full-length TK and probably result from translational initiation at Met46 and Met60, the second and third ATG codons of the tk reading frame. Male mice of most transgenic lines were sterile, and the severity of the lesion in spermatogenesis was directly related to the level of TK expression. In the most highly expressing lines, sperm counts were low and morphologically defective sperm were common. In other sterile lines, TK was expressed at a lower level and sperm counts were normal but sperm motility was greatly reduced. Lines with the lowest levels of HSV-1 TK expression were fertile. HSV-1 TK was expressed in germ line cells, mainly in the haploid spermatids. However, low-level HSV-1 TK activity was found in the testis before the first germ cells entered meiosis, showing that if expression is confined to the germ cells, it also occurs in spermatogonia.

Animals↗
PubMed1990

Expression of human immunodeficiency virus 1 (HIV-1) envelope gene products transcribed from a heterologous promoter. Kinetics of HIV-1 envelope processing in transfected cells.

The expression of human immunodeficiency virus 1 (HIV-1) envelope glycoprotein products was studied in cells transfected with env gene constructs transcribed from an SV40 promoter. Gene constructs possessing the complete tat, rev (tat+ rev+) and env genes were transiently expressed in COS-1 cells as precursor SU-TM (gp160), SU.TM (gp120 x 41), and nucleolar rev protein. In addition, envelope glycoprotein was detected on the surface of those transfected COS-1 cells expressing abundant levels of env protein. Transfected constructs possessing a mutated tat translational initiation codon (tat-rev+) were expressed in COS-1 cells with at least a 10-fold increase in the level of envelope glycoprotein expression compared to the analogous constructs with an intact tat AUG codon (tat+ rev+). Mutation of the rev initiation codon (tat+ rev-) and (tat-rev-) resulted in no detectable expression of env products but expression of these proteins could be rescued by co-transfection of a cDNA encoding the rev gene. Subgenomic tat/rev transcripts were detected following transfection of all of the gene constructs indicating splicing of the env mRNAs transcribed from a heterologous promoter. Unspliced env transcripts were only detected in the cytoplasm of cells transfected with (rev+) constructs or with the (tat- rev-) construct in the presence of the rev cDNA supplied in trans. In contrast, unspliced transcripts were detected in the nuclear and total cellular RNA of all transfected cells. Expression of rev protein was localized to the nucleolus of transfected COS-1 cells. These results indicate that the export of unspliced env mRNA to the cytoplasm is facilitated by the expression of rev. Following env synthesis, the conversion of SU-TM (gp160) to SU.TM (gp120 x 41) was not quantitative. After a 20-h pulse-chase, only 40% of the SU-TM (gp160) present at the start of the chase period was subsequently accountable as mature SU (gp120), and approximately 30% of the detectable SU (gp120) was found in the culture medium of transfected COS-1 cells. The findings indicate that the surface expression of SU.TM (gp120 x 41) derived from heterologous gene transcripts is modulated (i) the co-expression of rev, (ii) the efficiency of proteolytic processing of SU-TM (gp160), and (iii) the degree of SU (gp120) shedding and/or secretion from the cell.

Animals↗
PubMed1990

Differences in human cell lines to support stable replication of Epstein-Barr virus-based vectors.

Vectors carrying the origin of replication, ori-P, of the Epstein-Barr virus (EBV) are maintained extrachromosomally in human cells expressing the EBV nuclear antigen 1 (EBNA-1). We have studied the EBV vectors p201 and p292 in which both ori-P and EBNA-1 functions are present using the human cell lines A431 and HeLa. The two lines showed differences in their transfectability by the EBV vectors. Thousands of HeLa transfectants were obtained with either vector and these remained intact as episomes. A431 could only be efficiently transfected with p292 and a high ratio of chromosomal integrations and rearrangements were observed. The vector p292 expressed the EBNA-1 gene more efficiently than p201 and this was found to be associated with a harmful effect on the grown of both HeLa and A431 lines. These results indicate that EBV vectors behave differently, depending on the cell line and that over-expression of EBNA 1 from these vectors may be detrimental to the cells.

Antigens, Viral↗
PubMed1990

SCAN. Schedules for Clinical Assessment in Neuropsychiatry.

After more than 12 years of development, the ninth edition of the Present State Examination (PSE-9) was published, together with associated instruments and computer algorithm, in 1974. The system has now been expanded, in the framework of the World Health Organization/Alcohol, Drug Abuse, and Mental Health Administration Joint Project on Standardization of Diagnosis and Classification, and is being tested with the aim of developing a comprehensive procedure for clinical examination that is also capable of generating many of the categories of the International Classification of Diseases, 10th edition, and the Diagnostic and Statistical Manual of Mental Disorders, revised third edition. The new system is known as SCAN (Schedules for Clinical Assessment in Neuropsychiatry). It includes the 10th edition of the PSE as one of its core schedules, preliminary tests of which have suggested that reliability is similar to that of PSE-9. SCAN is being field tested in 20 centers in 11 countries. A final version is expected to be available in January 1990.

Algorithms↗
PubMed1990

Expression of a foreign gene in a line of transgenic mice is modulated by a chromosomal position effect.

Unusual aberrant expression of a foreign gene in a particular transgenic mouse line is often attributed to chromosomal position effect, although proof of this is lacking. An alternative explanation is that expression has been modified by the arrangement of multiple copies of the foreign gene at the insertion site or by mutation or gene rearrangement. We have distinguished between these explanations in the case of one particular transgenic line by recovering the aberrantly expressed foreign DNA and reintroducing it into the mouse genome to produce secondary transgenic mice. The expression pattern of the gene in the secondary transgenic mice was normal, showing that this case of aberrant expression is due to a chromosomal position effect.

Animals↗
PubMed1990

A phase I-II study of cyclophosphamide, thiotepa, and carboplatin with autologous bone marrow transplantation in solid tumor patients.

The principles of dose-response and combination chemotherapy were basic to the design of the initial curative standard-dose treatment regimens for leukemias, lymphomas, and testis cancer. Agents were selected with different dose-limiting toxicities, resulting in subadditive toxicity in combination. A fourth principle in the design of curative regimens was to combine agents with different mechanisms of action to avoid cross-resistance. Based on these principles, combinations of the highest tolerated doses of active noncross-resistant agents are required to decrease the emergence of drug resistance and achieve optimum cytotoxicity. Hematopoietic stem-cell support provides a mechanism for significantly increasing the doses of active agents, a strategy that has resulted in the cure of 10% to 50% of selected patients with lymphoma who could not be cured with standard-dose therapy. The lack of sufficiently effective cytoreductive conditioning regimens remains the major impediment to improving the high-dose therapy of patients with solid tumors. In this study, 27 patients with solid tumors were treated with a combination of cyclophosphamide, thiotepa, and carboplatin (CTCb) in a phase I-II study. Severe mucositis and neurotoxicity were dose-limiting. The maximum-tolerated dose (MTD) of the combination was 6.0 g/m2 of cyclophosphamide, 500 mg/m2 of thiotepa, and 800 mg/m2 of carboplatin. There were two deaths (7%) of sepsis, and an overall response rate of 72% in refractory tumors (81% in breast cancer). CTCb is a combination with low morbidity and high cytoreductive efficacy designed to exploit the principles of curative cancer chemotherapy.

Adult↗
PubMed1990

Severe withdrawal symptoms after discontinuation of alprazolam in eight patients with combat-induced posttraumatic stress disorder.

Eight patients with combat-induced chronic posttraumatic stress disorder (PTSD) receiving long-term alprazolam therapy for anxiety or depression (maximum dose of 2-9 mg/day for 1-5 years) had alprazolam therapy withdrawn. Most of the patients underwent gradual medication withdrawal. All patients had a prior history of alcohol abuse or benzodiazepine dependence. During withdrawal, all patients had severe reactions including anxiety, sleep disturbance, rage reactions, hyperalertness, increased nightmares, and intrusive thoughts; and 6 of the 8 patients had homicidal ideation. As a result of this report, the authors suggest that the potential for severe withdrawal reactions, even with gradual tapering, should be considered before prescribing alprazolam therapy for this group of patients.

Adult↗
PubMed1989

Computed tomographic features of esthesioneuroblastoma.

Esthesioneuroblastomas are uncommon neoplasms of the superior nasal cavity originating from olfactory epithelium. High resolution CT features of this neoplasm have not been well studied. Nine cases of esthesioneuroblastoma were reviewed to evaluate findings on high resolution CT. Homogeneous soft tissue masses with relatively uniform enhancement centered in the superior nasal cavity are characteristic. Bony erosion is frequent and usually accompanied by molding of bone. Staging, determined by extension and critical for treatment decisions, is well evaluated by CT.

Adult↗
PubMed1989

Effect of methotrexate alone and in combination with antifungal drugs on the growth of Candida albicans.

Methotrexate, at concentrations corresponding to drug levels found in vivo, caused a marked reduction in blastospore growth of Candida albicans strains in vitro, but did not affect germ tube elongation during the first 6 h after blastospores were shifted to conditions favouring hyphal formation. Combinations of methotrexate with amphotericin B, flucytosine and itraconazole showed no potentiation or antagonism of the antifungal effect of either component in tests with the blastospore form of C. albicans. In contrast, potentiation occurred when methotrexate-itraconazole combinations were tested for their effect on germ tube elongation of an azole-sensitive strain of C. albicans. This effect was not seen in tests with an azole-resistant strain.

Amphotericin B↗
PubMed1989

Assessment of a PstI polymorphism of the apolipoprotein-AI gene in Australian patients with coronary artery disease.

In 1986 Ordovas et al., reported that a polymorphism in the 3' flanking region of the apolipoprotein AI gene was strongly associated with premature coronary artery disease. This polymorphism affects a restriction site for the endonuclease PstI, resulting in the identification of a 3.3 kb band, rather than the more common 2.2 kb band, when genomic blots of PstI digested human DNA are probed with an apolipoprotein AI gene probe. In a study population of 88 patients with severe coronary artery disease before the age of 60, 28 (32%) carried the 3.3 kb allele, which was found in only five (4%) of 123 randomly chosen control subjects. In the present study, we have assessed the prevalence of this polymorphism in coronary artery disease patients and outpatients with abnormal lipid levels at the Alfred Hospital, Melbourne, and in normal volunteers. The 3.3 kb allele was present in 7-12% of subjects in these populations, and showed no association with coronary artery disease.

Aged↗
PubMed1989

Teacher expectations in infant school: associations with attainment and progress, curriculum coverage and classroom interaction.

There is still much debate, particularly in North America, about whether teachers' expectations have an effect on pupils' achievement, and through which factors expectations might be mediated. This paper reports on associations between teachers' academic expectations at the beginning, and children's attainments at the end of the school year. The study took place in infant schools in London. Associations were significant during all three years of infant school, and were not explained by children's attainments at the time of the expectation rating. Range of effects, in standard deviation units, of associations between expectations and progress over the school year ranged from 0.4 to 0.8. Two possible mediating factors between expectations and attainment were explored: differential curriculum coverage and differential classroom behaviour. It was found that children for whom teachers had higher expectations were given a wider range of activities in written language and mathematics, and this was so over and above attainments at the beginning of the school year. In contrast, there was no evidence that expectations were related to measures of classroom interaction like teacher praise and instructional contact.

Achievement↗
PubMed1989

Bronchial artery ligation modifies pulmonary edema after exposure to smoke with acrolein.

Pulmonary edema can follow smoke inhalation and is believed to be due to the multiple chemical toxins in smoke, not the heat. We have developed a synthetic smoke composed of aerosolized charcoal particles to which one toxin at a time can be added to determine whether it produces pulmonary edema. Acrolein, a common component of smoke, when added to the synthetic smoke, produced a delayed-onset pulmonary edema in dogs in which the extravascular lung water (EVLW) as detected by a double-indicator technique began to rise after 42 +/- 2 (SE) min from 148 +/- 16 to 376 +/- 60 ml at 165 min after smoke exposure. The resulting pulmonary edema was widespread macroscopically but appeared focal microscopically with fibrin deposits in alveoli adjacent to small bronchi and bronchioles. Bronchial vessels were markedly dilated and congested. Monastral blue B when injected intravenously leaked into the walls of the bronchial vessels down to the region of the small bronchioles (less than or equal to 0.5 mm ID) of acrolein-smoke-exposed dogs but not into the pulmonary vessels. Furthermore, ligation of the bronchial arteries delayed the onset of pulmonary edema (87 +/- 3 min, P less than 0.05) and lessened the magnitude (232 +/- 30 ml, P less than 0.05) at 166 +/- 3 min after acrolein-smoke exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrolein↗