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Biomedical subjects

M Towers

Publications and source records attributed to M Towers.

At least 19 recordsLinked to original sources
PubMed2000

The expression of D-cyclin genes defines distinct developmental zones in snapdragon apical meristems and is locally regulated by the Cycloidea gene.

Three D-cyclin genes are expressed in the apical meristems of snapdragon (Antirrhinum majus). The cyclin D1 and D3b genes are expressed throughout meristems, whereas cyclin D3a is restricted to the peripheral region of the meristem, especially the organ primordia. During floral development, cyclin D3b expression is: (a) locally modulated in the cells immediately surrounding the base of organ primordia, defining a zone between lateral organs that may act as a developmental boundary; (b) locally modulated in the ventral petals during petal folding; and (c) is specifically repressed in the dorsal stamen by the cycloidea gene. Expression of both cyclin D3 genes is reduced prior to the cessation of cell cycle activity, as judged by histone H4 expression. Expression of all three D-cyclin genes is modulated by factors that regulate plant growth, particularly sucrose and cytokinin. These observations may provide a molecular basis for understanding the local regulation of cell proliferation during plant growth and development.

Amino Acid Sequence↗
PubMed1996

Computed tomography appearance of idiopathic aneurysm of the azygos vein.

True idiopathic aneurysm of the azygos vein is a rarely described abnormality. The authors present a case of this anomaly in a 70-year-old woman with a history of rectal carcinoma. The aneurysm was found incidentally on computed tomography, performed to characterize the appearance of a lung nodule. The aneurysm decompressed when the patient was upright. The effects of respiratory and postural manoeuvres on the lesion are discussed and the computed tomography appearance is described.

Adenocarcinoma↗
PubMed1995

Steroid-responsive interstitial lung disease in patients receiving 2'-deoxy-5-fluorouridine-infusion chemotherapy. A report of three cases.

BACKGROUND: Continuous infusion of 2'-deoxy-5-fluorouridine (FUdR) has shown promise in its activity against metastatic renal cell carcinoma. Its side-effect profile is dominated by gastrointestinal toxicity; there are no known adverse pulmonary reactions. To the authors' knowledge, this is the first report on the development of lung toxicity in three patients receiving FUdR-infusion chemotherapy for metastatic renal cell carcinoma. METHODS: The hospital charts of three patients presenting with pulmonary symptoms during FUdR chemotherapy were reviewed. A literature search was performed regarding FUdR-related pulmonary toxicity. RESULTS: Nonproductive cough, dyspnea, and fever appeared within the 10th chemotherapy cycle. Chest radiographs showed interstitial disease in each case, accompanied by a restrictive pattern by pulmonary-function testing. Lung biopsies were performed on two patients showing a pattern of interstitial inflammation. Discontinuing FUdR and instituting steroidal therapy invariably improved symptoms, as was evident by chest radiographs and pulmonary function tests. In one patient, resuming FUdR treatment resulted in a recurrence of the respiratory symptoms, which was controlled with an increased steroidal dose. All three patients required low dose steroids to maintain their baseline respiratory functions. CONCLUSIONS: 2'-deoxy-5-fluorouridine-related lung toxicity is an uncommon event and occurs late in the treatment course. It is rapidly symptomatic and responds readily to steroidal therapy.

Aged↗
PubMed1995

Traumatic aortic disruption: false positive diagnosis on transesophageal echocardiography.

A case is described in which there was a high index of suspicion for traumatic aortic disruption. Because angiography was equivocal, transesophageal echocardiography was performed, and interpreted as showing a noncircumferential aortic tear. At thoracotomy, however, no tear was seen. The false positive interpretation was caused by a crescent-shaped atherosclerotic plaque.

Aorta, Thoracic↗
PubMed1992

Role of intraoperative ultrasonography in hepatic surgery: a preliminary report.

Twenty-four patients who underwent ultrasonography during hepatic surgery in the 22 months from October 1989 to July 1991 were studied prospectively to determine the value, if any, of intraoperative ultrasonography. For 6 (25%) of the 24 patients the operative plan was altered because of the ultrasonographic findings. In one of them resection was extended from a left lateral segmentectomy or sectorectomy to a left hemihepatectomy. In the other five patients the planned liver procedure was abandoned. Two of these five patients were cirrhotic--in one of them an additional metastasis was seen, and in the other there was tumour invasion of the portal vein. Of the three noncirrhotic patients, one had tumour invasion of the right hepatic vein, and the other two patients had additional metastases in the caudate lobe (Couinaud segment 1). Ultrasonography was found to be useful in 25% of patients who underwent this investigation during hepatic surgery--it avoided liver resections that would have failed because of advanced malignant disease.

Humans↗
PubMed1986

Prospective randomized double-blind trial of nabilone versus domperidone in the treatment of cytotoxic-induced emesis.

A prospective randomized double-blind trial comparing the butyrophenone analogue domperidone (D) and the synthetic cannabinoid nabilone (N) in the treatment of cytotoxic-induced emesis was conducted in 38 patients receiving highly emetogenic chemotherapy regimens (70% containing cisplatin). Patients received 20 mg D or 1 mg N the night before chemotherapy and 8-hourly on each chemotherapy day for two consecutive cycles of treatment. Three of 19 patients randomized to N completed only one cycle because of disease progression or subjectively adverse effects. Four of 19 patients completed only one cycle of D because of lack of efficacy or chemotherapy toxicity. In all, 32 cycles of N and 33 cycles of D were evaluable for efficacy. The mean number of vomiting episodes in cycle 1 was 4.76 for N and 12.95 for D (P less than 0.02). The corresponding values for cycle 2 were 4.27 and 7.69 (P greater than 0.10), and for cycles 1 and 2 combined, 4.53 for N and 10.81 for D (P less than 0.01). Nausea and food intake scores did not differ significantly, although there was a trend towards less nausea and an increased food intake with N. Subjectively adverse effects were more frequent with N and included drowsiness, dizziness, dry mouth, and postural hypotension. N is superior to D for the control of cytotoxic-induced emesis.

Adult↗
PubMed1983

Visual versus computerised assessment of left ventricular function from cinéangiography.

Visual assessment of left ventricular function from cinéangiography was compared with computerised assessment in 48 randomly selected cinéangiograms. The parameters compared included end-diastolic volume, end-systolic volume, stroke volume, ejection fraction and left ventricular output. There was poor agreement between visual and calculated values for end-diastolic volume, stroke volume and left ventricular output, but good agreement for ejection fraction and moderately good agreement for end-systolic volumes. Absolute values are particularly difficult to assess.

Cardiac Output↗
PubMed1981

Surgical treatment of mitral regurgitation caused by floppy valves: repair versus replacement.

Between October 1969 and April 1980, 132 patients underwent operation for floppy mitral valve. The 46 patients in group A underwent valve replacement using an inverted, fresh, unstented, antibiotic-sterilized aortic homograft and the 86 patients in group B underwent valve repair. The onset of symptoms was sudden. More than 80% of the patients in both groups were in New York Association functional class III or IV. The dominant lesion in both groups was ruptured chordae to the posterior cusp (72% in group A and 58% in group B). There were five early deaths (11%) and 15 late deaths (32%) in group A and four early deaths (5%) and five late deaths (7%) in group B. The actuarial survival rate at 5 years was 62% in group A and 90% in group B. In group A, five patients (11%) had valve failure, which led to late death in two. Four patients (8%) in group A required reoperation. Two patients in group B developed a loud mitral systolic murmur soon after operation and required reoperation. Two patients in group B had thromboembolism before routine anticoagulation. Sixteen patients (61%) in group A and 56 (76%) in group B were functional class I after operation.

Anticoagulants↗
PubMed1980

The use of "fresh" unstented homograft valves for replacement of the aortic valve. Analysis of 8 years' experience.

Between August, 1969 and May 1978, 679 patients underwent homograft replacement of the aortic valve. Isolated elective valve replacement was performed in 411 patients. Thirty-four patients had total aortic root replacement with reimplantation of the coronary arteries. There were 16 early deaths (3.9%) and 43 late deaths (10.5%) during a follow-up between 3 and 102 months (mean 47 months). Actuarial analysis showed 87% survival at 5 years and 81% at 8 years. Valve failure occurred in 24 patients (5.9%) owing to prolapse of one cusp in eight patients (2.0%), infective endocarditis in seven patients (1.7%), and degeneration of the valve in nine patients (2.2%). Degenerative valve failure was encountered after the fourth year with an incidence of 4.8% of patients at risk and occurred only in grafts from donors over the age of 65 years. Diastolic murmurs were present in 28% of patients followed beyond 1 month and increased very slightly with time. Systemic embolism was not recorded in any patient despite the fact that anticoagulants were not used. The clinical results were judged to be good or excellent in 89% of patients. It is concluded that homograft replacement of the aortic valve gives satisfactory results with a low incidence of late valve failure.

Adolescent↗
PubMed1979

Influence of preoperative left ventricular function on results of homograft replacement of the aortic valve for aortic stenosis.

The effect of preoperative left ventricular function on early and late prognosis was assessed in 103 patients with aortic stenosis who underwent left ventricular cineangiography before homograft replacement of the aortic valve. The patients were separated into two groups: Group A (58 patients) with an ejection fraction of 0.46 or more and Group B (45 patients) with an ejection fraction of 0.45 or less. The two groups were compared with respect to clinical and hemodynamic data as well as operative result. There was poor correlation between clinical data and left ventricular function. In Group A there were three early deaths (5.2 percent) and three late deaths (5.2 percent) compared with no early and six late deaths (13.3 percent) in Group B during the follow-up period of 12 to 102 months (mean 43 months). Most patients in Group B showed considerable symptomatic improvement but less than that observed in Group A. Forty-two patients (13 in Group A and 29 in Group B) underwent repeat cardiac catheterization and coronary angiography. Improvement in left ventricular function as assessed by radial analysis of segmental wall motion and ejection fraction was observed in 20 of the 29 patients in Group B. Failure of left ventricular function to improve was associated with additional coronary artery disease in the majority of patients. It is concluded that poor left ventricular function does not increase the risk of aortic valve replacement for aortic stenosis and that improvement in left ventricular function can be expected in the majority of patients.

Adolescent↗
PubMed1979

Influence of preoperative left ventricular function on results of homograft replacement of the aortic valve for aortic regurgitation.

The effect of preoperative left ventricular function on eraly and late prognosis was assessed in 69 patients with aortic regurgitation who underwent homograft replacement of the aortic valve. Patients were divided into two groups: Group A (38 patients) had an ejection fraction of 0.46 or more and Group B (31 patients) had an ejection fraction of 0.45 or less. Clinical data, hemodynamic data, and operative results were compared in the two groups. In Group A there was one early death (2.6%) and there were two late deaths (5.3%) compared to two early deaths (6.5%) and seven late deaths (22.6%) in Group B during a follow-up period of 13 to 98 months (mean, 49 months). Actuarial analysis showed a 94% survival at 6 years in Group A compared to 80% in Group B. Twenty-four patients were reinvestigated by repeat cardiac catheterization and coronary angiography at a mean time of 38 months following valve replacement. Left ventricular function was assessed by computerized quantitative radial analysis of segmental wall motion. Improvement in left ventricular function occurred in eight of the 14 patients reinvestigated in Group B, and appeared to be closely related to the etiology of the initial valve lesion. Despite the higher mortality rate in patients with poor left ventricular function, most derived considerable benefit from operation.

Adolescent↗
PubMed1977

The use of "fresh" unstented homograft valves for replacement of the aortic valve: analysis of 6 1/2 years experience.

Between August 1969 and January 1976, 561 patients underwent homograft replacement of the aortic valve (AVR). Isolated AVR was performed in 339 patients, ranging in age between 18 months and 74 years. The valves were sterilized in antibiotic solution and preserved at 4 degrees C in tissue culture medium. There were 11 early deaths (3.2%) and 23 late deaths (6.8%). Actuarial analysis showed 88% survival at 5 years and 85% at 6 years. Valve failure occurred in 13 patients (3.8%) due to prolapse of one cusp in five patients (1.5%), infective endocarditis in three and degeneration of the graft in five (1.5%). Degenerative valve failure was encountered after the fourth year with an incidence of 3.5% of patients at risk, and occurred only in grafts from donors over the age of 70 years. Diastolic murmurs were present in 22% of patients followed up for more than one month and increased very slightly with time. The clinical result was judged to be good or excellent in approximately 90% of the surviving patients.

Adolescent↗