A Bub2p-dependent spindle checkpoint pathway regulates the Dbf2p kinase in budding yeast.

Exit from mitosis in all eukaroytes requires inactivation of the mitotic kinase. This occurs principally by ubiquitin-mediated proteolysis of the cyclin subunit controlled by the anaphase-promoting complex (APC). However, an abnormal spindle and/or unattached kinetochores activates a conserved spindle checkpoint that blocks APC function. This leads to high mitotic kinase activity and prevents mitotic exit. DBF2 belongs to a group of budding yeast cell cycle genes that when mutated prevent cyclin degradation and block exit from mitosis. DBF2 encodes a protein kinase which is cell cycle regulated, peaking in metaphase-anaphase B/telophase, but its function remains unknown. Here, we show the Dbf2p kinase activity to be a target of the spindle checkpoint. It is controlled specifically by Bub2p, one of the checkpoint components that is conserved in fission yeast and higher eukaroytic cells. Significantly, in budding yeast, Bub2p shows few genetic or biochemical interactions with other members of the spindle checkpoint. Our data now point to the protein kinase Mps1p triggering a new parallel branch of the spindle checkpoint in which Bub2p blocks Dbf2p function.

DNA replication is completed in Saccharomyces cerevisiae cells that lack functional Cdc14, a dual-specificity protein phosphatase.

The Cdc14 protein encodes a dual-specificity protein phosphatase which functions in late mitosis, and considerable genetic evidence suggests a role in DNA replication. We find that cdc14 mutants arrested in late mitosis maintain persistent levels of mitotic kinase activity, suggesting that Cdc14 controls inactivation of this kinase. Overexpression of Sicl, a cyclin-dependent protein kinase inhibitor, is able to suppress telophase mutants such as dbf2, cdc5 and cdc15, but not cdc14. It does, however, force cdc14-arrested cells into the next cell cycle, in which an apparently normal S phase occurs as judged by FACS and pulsed-field gel electrophoretic analysis. Furthermore, in a promoter shut-off experiment, cells lacking Cdc14 appear to carry out a normal S phase. Thus Cdc14 functions mainly in late mitosis and it has no essential role in S phase.

Angioscopy of culprit coronary lesions in unstable angina pectoris and correlation of clinical presentation with plaque morphology.

This study demonstrates that plaque disruption and thrombus are absent in a considerable number of patients with unstable angina and that culprit lesion morphologies as assessed by angioscopy may differ among the various clinical subsets of patients. Although plaque disruption and thrombus undoubtedly play an important role in the pathogenesis of unstable angina, alternative mechanisms may be responsible for ischemia in some patients.

Angioscopic assessment of coronary lesions underlying thrombus.

This study examines the characteristics of coronary lesions in which thrombus is found as assessed by angioscopy before percutaneous transluminal coronary angioplasty in patients with various coronary syndromes. Our findings demonstrate that the plaque underlying intracoronary thrombus is usually yellow and/or disrupted, and support in vitro observations that lipid-rich plaques are highly thrombogenic and that disruption of these plaques is associated with in situ thrombosis.

Eastern Health Board Regional Orthodontic Service: an initial audit.

This initial audit of 600 recently assessed Eastern Health Board orthodontic patients suggests that a large number of them (47 per cent) requires referral for routine restorative and preventive dental care. Closer links are needed with general dental practitioners and community dental surgeons to resolve these needs. The trend for a high referral of females and Class 11 Division 1 malocclusion type correlated well with studies in other countries.

Determination of aortic valve area in valvular aortic stenosis by direct measurement using intracardiac echocardiography: a comparison with the Gorlin and continuity equations.

OBJECTIVES: This study sought to 1) show that intracardiac echocardiography can allow direct measurement of the aortic valve area, and 2) compare the directly measured aortic valve area from intracardiac echocardiography with the calculated aortic valve area from the Gorlin and continuity equations. BACKGROUND: Intracardiac echocardiography has been used in the descriptive evaluation of the aortic valve; however, direct measurement of the aortic valve area using this technique in a clinical setting has not been documented. Despite their theoretical and practical limitations, the Gorlin and continuity equations remain the current standard methods for determining the aortic valve orifice area. METHODS: Seventeen patients underwent intracardiac echocardiography for direct measurement of the aortic valve area, including four patients studied both before and after valvuloplasty, for a total of 21 studies. Immediately after intracardiac echocardiography, hemodynamic data were obtained from transthoracic echocardiography and cardiac catheterization. RESULTS: Adequate intracardiac echocardiographic images were obtained in 17 (81%) of 21 studies. The average aortic valve area (mean +/- SD) determined by intracardiac echocardiography for the 13 studies in the Gorlin analysis group was 0.59 +/- 0.18 cm2 (range 0.37 to 1.01), and the average aortic valve area determined by the Gorlin equation was 0.62 +/- 0.18 cm2 (range 0.31 to 0.88). The average aortic valve area determined by intracardiac echocardiography for the 17 studies in the continuity analysis group was 0.66 +/- 0.23 cm2 (range 0.37 to 1.01), and that for the continuity equation was 0.62 +/- 0.22 cm2 (range 0.34 to 1.06). There was a significant correlation between the aortic valve area determined by intracardiac echocardiography and the aortic valve area calculated by the Gorlin (r = 0.78, p = 0.002) and continuity equations (r = 0.82, p < 0.0001). CONCLUSIONS: In the clinical setting, intracardiac echocardiography can directly measure the aortic valve area with an accuracy similar to the invasive and noninvasive methods currently used. This study demonstrates a new, quantitative use for intracardiac echocardiographic imaging with many potential clinical applications.

Ovarian irradiation and prednisone following surgery and radiotherapy for carcinoma of the breast.

Following mastectomy, patients aged 35 to 76 years with operable breast cancer underwent postoperative irradiation of the chest wall and regional lymph nodes. They were then assigned at random to receive no further therapy (NT), ovarian irradiation (R) 2000 rads in 5 days, or ovarian irradiation in the same dosage plus prednisone (R + P) 7.5 mg daily for up to five years. A total of 703 eligible patients received the randomly assigned treatment. The median follow up was 21 years with a range of 14 to 25 years. Overall, there was a delay in recurrence (p = 0.03) and survival was prolonged (p = 0.19) for patients who received R, but in neither case was the difference significant after adjusting for the multiplicity in our data. Overall, patients who received R + P experienced a significant delay in recurrence (p = 0.0003) and a significantly prolonged survival (p = 0.005), even after adjusting for multiple comparisons. In premenopausal patients who received R, the recurrence of breast cancer was delayed and survival prolonged, but not significantly. In premenopausal women aged 45 years or more, R + P therapy significantly prolonged survival (p = 0.0004), while the delay in recurrence although significant (p = 0.02) was only marginally so after allowance for multiple comparisons. No value was demonstrated for ovarian irradiation with or without prednisone therapy in postmenopausal patients. A new finding in this review was that contralateral breast cancer as the first failure was reduced by R + P compared to NT in the overall group.

Drug metabolizing enzymes of mussels as bioindicators of chemical pollution.

The GSTs of M. edulis provide an easily assayed activity which would be expected to respond to changes in pollution status. The main GST and a related GSH-binding protein have been purified and biochemically characterized. The former protein is most similar to the Pi class while the latter is a catalytically inactive monomer which appears to be related to the Mu class. This enzyme activity has been assessed as a potential indicator of exposure to chemical pollutants in both Cork Harbour and Venice Lagoon (using the closely related species, M. galloprovincialis). Controlled exposure studies with mussels in holding tanks have indicated that the herbicide aldicarb gives a slight but significant increase in GST activity consistent with the inducibility of these enzymes by xenobiotics in this bivalve. At present, we are studying samples which have been deliberately exposed to PAH and PCB compounds. Studies of this type are important in helping to understand the effects and fate of chemical pollutants released into estuarine environments.

Characterization of a glutathione S-transferase and a related glutathione-binding protein from gill of the blue mussel, Mytilus edulis.

The major isoenzyme of glutathione S-transferase (GST 1) was purified to homogeneity from cytosolic extracts of Mytilus edulis gill tissue by GSH-agarose affinity chromatography followed by Mono Q ion-exchange f.p.l.c. This enzyme was particularly active with 1-chloro-2,4-dinitrobenzene, ethacrynic acid and cumene hydroperoxide as substrates. Immunoblotting and amino acid sequencing studies indicate that the enzyme belongs to the Pi class of GSTs. A related protein which binds to GSH-agarose was also purified. This GSH-binding protein did not immunoblot with GST antisera and showed no detectable catalytic activity with GST substrates although its N-terminal sequence was similar to Mu-class GSTs. Gel-filtration chromatography indicated that GST 1 is a dimer and the GSH-binding protein a monomer. Mass spectrometry and SDS/PAGE indicate subunit molecular masses of 24 kDa (GST 1) and 25 kDa (GSH-binding protein), respectively. Both proteins have amino acid compositions typical of GSTs.

3D image reconstruction of right subclavian artery aneurysms.

OBJECTIVE: Three-dimensional (3D) image reconstruction methods allied to spiral CT (SCT) or MR angiography (MRA) are used in clarifying the anatomy of complex aortic anatomy. MATERIALS AND METHODS: Two patients with superior mediastinal masses suggestive of aneurysms of the anomalous right subclavian artery were examined. Both patients were examined using breath-hold SCT and one by breath-hold MRA. Three-dimensional images were reconstructed using a surface rendering technique for the SCT examinations and by a maximum intensity projection technique for MRA. RESULTS: Two cases of aneurysmal anomalous right subclavian artery were diagnosed by SCT with 3D image reconstruction. One case was also examined by MRA with 3D image reconstruction which confirmed the findings of SCT. The use of the 3D techniques clarified the complicated anatomy and avoided the need for angiography. CONCLUSION: Two cases are illustrated of 3D imaging of complicated aortic branch anatomy due to aneurysms of anomalous right subclavian artery. Image quality was good and no further imaging by more invasive techniques was required.

Separation of multiple forms of glutathione S-transferase from the blue mussel, Mytilus edulis.

1. Glutathione S-transferase isoenzymes from Mytilus edulis and M. galloprovincialis have been partially purified by glutathione-sepharose affinity chromatography followed by Mono Q anion exchange fast protein liquid chromatography (f.p.l.c.). 2. The tissue distribution of glutathione S-transferase in M. edulis has been studied. Using 1-chloro-2,4-dinitrobenzene as substrate, highest specific activity is observed in the gill, the main feeding organ. Affinity-purified extracts of this organ give a characteristic f.p.l.c. profile. A similar profile is obtained with affinity-purified extracts of the digestive gland of M. galloprovincialis. 3. The subunit structure of the purified isoenzymes has been studied by SDS polyacrylamide gel electrophoresis and reversed-phase h.p.l.c. The subunits have similar molecular weights and h.p.l.c. retention times to rat glutathione S-transferases.

Analysis of supradiaphragmatic clinical stage I and II Hodgkin's disease treated with radiation alone.

Patients with clinical Stage I and II Hodgkin's disease have been managed at the Princess Margaret Hospital for over 20 years, without the use of routine staging laparotomy. Our experience identified as adverse prognostic factors presence of a large mediastinal mass, B symptoms, and advanced age in presence of unfavorable histology (20). We had suggested previously that the use of extended field radiation therapy (XRT) was associated with a lower risk of relapse than involved field XRT or mantle XRT. There has been a trend over the past decade to select those patients with favorable prognostic factors for treatment with XRT alone and to use mantle plus upper abdominal XRT (extended field XRT) to treat them. A retrospective study of patients with clinical Stage I and II Hodgkin's disease treated at the Princess Margaret Hospital between 1978 and 1986 was conducted to determine the impact of patient selection and extended field radiation on outcome. The study involved 250 patients with supradiaphragmatic disease selected for treatment with radiation alone on the absence of adverse prognostic factors. Radiation techniques included involved field radiation in selected patients (those with upper neck involvement), mantle radiation in the earlier years, and mantle plus upper abdominal radiation in the later years of the study. Actuarial survival was 83.3% at 8 years; cause-specific survival was 90.1% and the relapse-free rate 71.6%. Local tumor control was 94.6%; only two patients had true infield failure. Multivariate analysis showed that significant prognostic factors included age, histology, and erythrocyte sedimentation rate. Extent of the radiation treatment volume was significant and influenced the risk of relapse, particularly out-of-field relapse, independently of other factors. A dose of 35 Gy was found to be sufficient for control of clinical disease. This study validated a previously developed model for the selection of clinically staged patients with Stage I and II Hodgkin's disease for treatment with radiation alone. Careful selection of these patients can yield excellent results without requiring that staging laparotomy be routinely performed or the use of systemic chemotherapy as the initial treatment.

A review of the oncology curriculum at Dalhousie medical school.

The teaching of oncology at Dalhousie medical school is currently left to the discretion of the 30 university departments. There is no central coordination. This organization leaves no monitoring of curriculum content to see that what should be covered is indeed covered, nor does it provide teaching from the perspective of oncology rather than the perspective of the other individual disciplines. Following an inventory of the oncology curriculum and a survey of interns graduating from Dalhousie in 1991, we recognize deficiencies in the clinical portion of the curriculum that could be rectified with a small number of hours designed to teach the various aspects of the management of cancer patients in case-scenario, student participation sessions.

Outcome analysis of localized gastrointestinal lymphoma treated with surgery and postoperative irradiation.

One hundred thirteen patients with localized gastrointestinal lymphoma treated by surgery and postoperative irradiation between 1967 and 1985 were reviewed. At 15 years, actuarial survival of this group was 40.6%, with a cause-specific survival of 69.2% and a relapse-free rate of 64%. Two-thirds of relapses occurred at distant sites. In Stage IA and IIA patients with no residuum or with positive resection margins, (N = 90) only site of involvement and stage predicted for relapse. Age, histologic subtype group, and depth of bowel wall invasion did not affect relapse risk. In the very favorable group (Stage IA, IIA, no residuum or microscopic residuum), 8.4% of patients with stomach lymphoma relapsed compared to 25% of patients with small bowel lymphoma. The risk of early relapse was higher in those with Stage IIA small bowel lymphoma than those with Stage IA small bowel lymphoma. We continue to recommend adjuvant abdominal irradiation for patients with Stage IA, IIA completely resected stomach lymphoma and Stage IA completely resected small bowel lymphoma. We recommend combined modality therapy for patients with completely resected Stage IIA small bowel lymphoma and all other localized gastrointestinal lymphoma where visible residual disease is present.

Ultrasound determination of the relationship of radioactive plaques to the base of choroidal melanomas.

There is an assumption that radioactive plaques placed at surgery are, and will remain, in proper relationship to the base of the tumor. The plaque dose is calculated based on this assumption. In fact, factors such as loose sutures, improper diameter estimations, pressure from adjacent rectus muscles, and intervening tissue (oblique muscles) can compromise this relationship. Ultrasound provides a practical method of imaging the tumor and plaque simultaneously. The authors have used postoperative ultrasound to monitor the accuracy of iodine-125 plaque placement in nine cases. Detection of eccentrically placed and malpositioned plaques provides valuable insight which can be used to refine surgical technique. Detection of plaque tilting by oblique muscles can serve as a basis for recalculating dosage. The relationship of plaque margins to vital ocular structures such as the optic nerve can also be determined by ultrasound.