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Biomedical subjects

J W Mackenzie

Publications and source records attributed to J W Mackenzie.

At least 19 recordsLinked to original sources
PubMed1992

One hundred consecutive patients undergoing video-assisted thoracic operations.

Video-assisted thoracic surgery is a new modality that allows visualization of and access to the intrathoracic organs without making a thoracotomy incision. One hundred consecutive patients underwent 113 thoracic procedures using this technique. Eight wedge resections for metastatic lesions, 6 pericardial windows, 1 bronchogenic cystectomy, 4 explorations of the aortopulmonary window, 1 decortication, 5 pleural scleroses, 8 bullous ablations, 25 lung biopsies, 19 wedge resections for carcinoma, 9 explorations of the thorax, 3 lobectomies, 1 esophageal cystectomy, 14 wedge resections for benign lesions, 4 pleurectomies, 1 excision of a neurogenic tumor, 3 mediastinal explorations, and 1 imaged axillary dissection were performed. There was no mortality. Ten patients had complications from which they recovered completely. Patients undergoing video-assisted thoracic operations seem to have reduced postoperative pain, shorter hospitalization, and quicker recovery times. Currently, this new modality appears to have beneficial value for patients; however, only further experience will determine its true merits.

Adolescent↗
PubMed1992

Factors affecting mitral valve reoperation in 317 survivors after mitral valve reconstruction.

From a very heterogeneous group of 340 patients undergoing mitral valve reconstruction from 1969 through 1988, 313 hospital survivors were analyzed for factors affecting the occurrence of reoperative mitral valve procedures related to native mitral valve dysfunction. Follow-up was 100% and extended from 1 year to 20 years (mean follow-up, 7.2 years). Sixty-three patients (18.5% of the 340) required mitral valve reoperation at a mean postoperative interval of 6 years (range, 1 to 15 years). Incremental risk factors analyzed for the event late mitral valve failure included age, sex, preoperative New York Heart Association class, cause of valvular disease, pathophysiology of the mitral valve, previous mitral valve operation, mitral valve pathology, and estimation of mitral valve function at operation after repair. Mitral valve pathophysiology affected the actuarial freedom from mitral valve replacement (p = 0.023 [log-rank]). Actuarial freedom from mitral valve reoperation was 90% at 5 years and 80% at 8 years in patients who had either pure mitral regurgitation or isolated mitral stenosis compared with 80% and 72% at 5 and 10 years, respectively, in patients who had mixed mitral stenosis and regurgitation (p = 0.023). Patients undergoing late reoperation were younger (51.7 +/- 1.56 years [+/- the standard error of the mean]) than those not having reoperation (p less than 0.0003). Durability of the repair was less in patients with rheumatic heart disease (p less than 0.025) and greater in patients with ischemic heart disease (p less than 0.004). Seventy-three percent of patients undergoing reoperation had concomitant operations compared with 68% of those not having reoperation (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Abnormalities in the biosynthesis of type III procollagen in cultured skin fibroblasts from two patients with multiple aneurysms.

We examined the synthesis of collagenous proteins by cultured skin fibroblasts taken from 14 patients with an abdominal aortic aneurysm and either an aneurysm at a second site (8 patients) or a first order relative with an abdominal aortic aneurysm (6 patients). Fibroblasts were labeled with [3H] proline and, following pepsin digestion of media proteins, the ratio of type I/III collagen was examined by denaturing polyacrylamide gel electrophoresis (SDS-PAGE). With the exception of two patients, the ratio of type I/III collagen in the media of fibroblasts from aneurysm patients was similar to control values (6 controls). In two of the patients, the type I/III collagen ratio was greater than 3 standard deviations from the mean of both control ratios and those of other aneurysm patients. mRNA levels coding for type III procollagen, however, were normal in both patients. Patient #1 (ME) showed reduced type III procollagen on SDS-PAGE analysis of intracellular proteins. Intracellular and media type III procollagen levels were normal in patient #2 (HR), but media type III collagen was reduced by over 50% after digestion with a combination of trypsin and alpha-chymotrypsin for 5 minutes at 36 degrees C. Control type III collagen was only reduced after digestion at 39 degrees C. These data suggest an altered thermal stability of the type III collagen trimer synthesized by this patient, probably due to a mutation in the amino acid sequence. The data presented in this paper suggest that some forms of common abdominal aortic aneurysms may be caused by mutations in the gene coding for type III procollagen.

Aged↗
PubMed1992

Video-assisted thoracic surgical resection of malignant lung tumors.

Forty patients with malignant pulmonary disease underwent evaluation, staging, and a biopsy or resection by means of video-assisted thoracic surgery. There were 20 men and 20 women whose ages ranged from 27 to 82 years. Eight patients had a wedge resection for metastatic carcinoma, three a lobectomy for primary carcinoma, six exploration of the thorax, five biopsy of the aortopulmonary window, and eighteen a sublobar resection for primary carcinoma of the lung. There was no mortality. Three patients had air leaks that lasted an average of 8 days. Video-assisted thoracic surgery seems to be useful for more precise staging of carcinoma of the lung, and, in some patients, resectional operations can be performed.

Adult↗
PubMed1991

The substitution of arginine for glycine 85 of the alpha 1(I) procollagen chain results in mild osteogenesis imperfecta. The mutation provides direct evidence for three discrete domains of cooperative melting of intact type I collagen.

We report a case of mild osteogenesis imperfecta in a 56-year-old male undergoing aortic valve replacement surgery. The primary defect in this patient was the substitution of arginine for glycine 85 in one of the two chains of alpha 1(I) procollagen. The thermal stability of the type I collagen synthesized by the patient's cultured skin fibroblasts was examined by enzymatic digestion. Digestion of the mutant type I collagen with trypsin and chymotrypsin at increasing temperatures sequentially generated three discrete collagenous fragments, approximately 90, 170, and 230 amino acids shorter than normal type I collagen. This incremental thermal denaturation is indicative of cooperative melting blocks within the type I collagen. This is the first demonstration of such cooperative blocks of melting in intact, essentially normal post-translationally modified type I collagen. This direct evidence for cooperative melting domains of uncut type I collagen suggests that discrete blocks of amino acids function as core sites stabilizing the collagen helix. The location of mutations of the alpha chains of type I collagen relative to these discrete blocks of amino acids may influence the severity of the disease phenotype.

Amino Acid Sequence↗
PubMed1991

Relationship between adenylate cyclase activity and regional myocardial energetics in experimental left ventricular hypertrophy.

The aim of this study was to examine the responsiveness of the hypertrophied left ventricle to beta-adrenergic stimulation in a pressure overload model produced by valvular aortic stenosis and characterized by reduced beta-adrenoceptor number. The study was designed to correlate changes in global and regional cardiac work and energetics in response to isoproterenol with adenylate cyclase activity. Eleven anesthetized dogs with left ventricular hypertrophy and 11 controls were studied at rest and during 0.5 and 1.0 micrograms/kg/min isoproterenol infusion. We measured regional work from segment length and force changes with ultrasonic dimension crystals and miniature force gauges in addition to arterial and left ventricular blood pressure and cardiac output. Regional myocardial oxygen consumption was calculated from O2 extraction using microspectrophotometry and blood flow using radioactively labeled microspheres. Adenylate cyclase activity was assayed at baseline and after stimulation with forskolin. Isoproterenol significantly increased heart rate, dP/dtmax, cardiac output, and external work to similar levels in control and hypertrophied animals. Similarly, regional work increased from 463 +/- 115 to 995 +/- 584 g x mm/min for controls and from 392 +/- 156 to 1175 +/- 577 for hypertrophied dogs with high dose isoproterenol. Regional O2 consumption also increased to similar levels (20.3 +/- 14.7 vs 16.2 +/- 6.3 ml O2/min/100 g) in both groups. Adenylate cyclase activity was lower in hypertrophy at baseline (23.9 +/- 7.3 vs 62.9 +/- 14.2 pM/min/mg protein for controls), but was the same as for controls with forskolin stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1991

Changes in aortic levels of tropoelastin mRNA following treatment of rats with the antihypertensive drugs captopril and hydralazine.

This manuscript describes changes in the steady state levels of aortic tropoelastin mRNA in spontaneously hypertensive rats (SHR) and normotensive controls (WKY) following treatment with two antihypertensive drugs. Three-week-old WKY and SHR rats were treated with hydralazine (15 mg/kg/day) or captopril (25 mg/kg/day). Tail artery blood pressure was monitored twice weekly. Both drugs prevented the development of hypertension in the SHR rat. At 6 weeks of age, total aortic RNA was extracted and the steady state levels of mRNAs coding for tropoelastin and pro alpha 1 (III) collagen were determined by slot blot hybridization analysis using radiolabeled tropoelastin and pro alpha 1 (III) collagen cDNA clones. Hydralazine treatment resulted in a threefold increase in tropoelastin mRNA levels in both the SHR and the WKY animals (P less than 0.01). Captopril-treated SHR animals demonstrated a similar significant increase. In contrast, no differences in pro alpha 1 (III) collagen mRNA levels were observed in the aorta of SHR or WKY rats following treatment with either captopril or hydralazine. These data suggest that antihypertensive agents can act specifically to directly induce tropoelastin mRNA levels in large arteries and thus may induce vascular remodeling independent of an increase in blood pressure.

Aging↗
PubMed1991

Desmoplasia in benign and malignant breast disease is characterized by alterations in level of mRNAs coding for types I and III procollagen.

Desmoplasia, the formation of excessive connective tissue surrounding some neoplasms, is a well documented, but incompletely understood phenomenon. To characterize the fibrotic response in benign breast conditions and malignancy, we examined the steady state levels of mRNA coding for types I and III procollagen in mild fibrocystic changes, in fibroadenoma, and in infiltrating ductal carcinoma. The results indicate that in mild fibrocystic change there is a relative increase in type III procollagen mRNA. In contrast, fibroadenoma and carcinoma are characterized by increased levels of type I procollagen mRNA.

Adult↗
PubMed1991

A novel approach to anxiolytic premedication for day-case patients.

The usefulness of 10 mg timolol orally as a non-sedative anxiolytic premedicant for day-case patients was examined in a double-blind placebo-controlled study. Patients were invited to take part by letter sent the week before gynaecological (n = 40) or oral (n = 60) surgery was scheduled. Indices of anxiety and alertness were obtained prior to administration of the tablet; quality of previous anaesthetic experience was also recorded. In those patients with no previous or unpleasant previous anaesthetic experience a significant reduction in anxiety amongst those given timolol was identified. Haemodynamic differences between the groups were not clinically significant, and return of psychomotor function was not delayed by timolol. Timolol effectively reduces situational anxiety, is non-sedative, and is advocated as a premedicant for anxious day-case patients and others in whom rapid return of psychomotor function is desirable.

Adolescent↗
PubMed1990

Homograft valve durability: host or donor influence?

Antibiotic sterilized valves have been shown to function longer than those chemically sterilized; however, the reason remains obscure. Current hypotheses cite either retention of donor fibroblasts capable of repairing the grafted valve, or host fibroblast ingrowth into and onto the leaflet ground substance. A cryopreserved aortic homograft from a male donor was explanted from a female recipient after 10 months, and subjected to immunocytochemistry, tissue culture, and karyotyping. The leaflet bases exhibited normal morphology with an intact endothelium. The distal one-third of the leaflets was devoid of fibroblasts from the leaflet bases showed them to be of host origin. This homograft seems to have been implanted with an intact ground substance which allowed for host cell repopulation of the inner one-third of the leaflets. Perhaps donor cell viability in itself is not as important to durability as is preservation of the leaflet ground substance, but rather the presence of viable cells may be an index of the structural integrity of the collagen and elastic matrix.

Adult↗
PubMed1990

The effect of interleukin-2 administration on wound healing in adriamycin-treated rats.

Adriamycin (doxorubicin hydrochloride), an effective chemotherapeutic drug, is also a potent inhibitor of wound healing. Conversely, certain polypeptide growth factors are capable of stimulating fibroblasts to secrete collagen, thus enhancing wound healing. The purpose of this study was to determine if interleukin-2 (IL-2), a T-cell growth factor, could reverse the wound healing deficit caused by Adriamycin. Adriamycin treatment caused a significant decrease in wound-breaking strength (P less than 0.005). IL-2 administration increased wound-breaking strength in Adriamycin-treated animals (2126 g vs 1549 g, P less than 0.005). In control animals, IL-2 did not increase wound-breaking strength significantly (2708 g vs 2608 g, P greater than 0.1). Histologically, wounds from Adriamycin-treated animals were less cellular, demonstrated less collagen in the dermis, and a lesser degree of capillary ingrowth. The number of fibroblasts in the dermal layer was increased in animals receiving IL-2. Control rats gained an average of 1.4% of their original body weight, while Adriamycin-treated rats lost an average of 19% of their original body weight (P less than 0.0005). IL-2 administration did not influence weight loss or gain. Hematologically, animals receiving Adriamycin had lower hemoglobin and hematocrit values and higher platelet counts. There were no differences in total white blood cell counts; however, animals receiving Adriamycin showed a predominance of polymorphonuclear leukocytes and a relative decrease in lymphocytes. Animals receiving IL-2 demonstrated a significant eosinophilia. (1) Adriamycin impairs normal wound healing. (2) Interleukin-2 administration improves the wound healing impairment caused by Adriamycin. (3) Interleukin-2 appears to increase infiltration of inflammatory cells, fibroblasts, and capillaries into the wound, which may account for the observed increase in wound breaking strength.

Animals↗
PubMed1990

Changes in vascular extracellular matrix accumulation reflect phenotypic differences between the arterial wall of pigeons resistant and susceptible to the development of spontaneous atherosclerosis.

White Carneau pigeons have previously been shown to be genetically susceptible to the development of spontaneous atherogenesis. The severity of development of atheromatous lesions is considerably greater than a more resistant breed of Show Racer pigeons. Analysis of levels of total hydroxyproline and isodesmosine in the thoracic aorta and celiac bifurcation of prelesion, six-week-old White Carneau and Show Racer pigeons, revealed an increased accumulation of total collagen and cross-linked elastin in the White Carneau arterial tissue. Using dot blot hybridization, measurements of steady state levels of several mRNAs in total RNA extracted from pigeon aortic tissue were also determined. While the increased deposition of extracellular matrix proteins was paralleled by a significantly greater recovery of mRNAs coding for pro alpha 1(1) collagen and elastin, in RNA extracted from White Carneau aortal tissue, increased recovery of mRNAs coding for an intracellular protein, gamma-actin were also observed in White Carneau aortal tissue. No differences in steady state levels of mRNAs coding for pro alpha 1(1) collagen and elastin were observed in RNA extracted from pigeon liver, suggesting a tissue specific increase in the mRNAs coding for these connective tissue proteins in aorta. A markedly reduced cell population however, was responsible for this overall increase in biosynthetic activity in White Carneau pigeon aortic tissue. This was demonstrated by a reduced cell count and by the recovery of reduced levels of total DNA in the thoracic aorta and celiac bifurcation of the White Carneau pigeon. The cell population in White Carneau aortic tissue exhibits therefore a markedly different phenotype with respect to a capacity for the biosynthesis of extracellular and intracellular proteins.

Actins↗
PubMed1990

Changes in steady-state levels of mRNAs coding for type IV collagen, laminin and fibronectin following capillary basement membrane thickening in human adult onset diabetes.

The development of capillary basement membrane thickening has been linked to microvascular changes known to occur in tissues of patients with type II diabetes. Previous evidence has suggested that capillary basement membrane thickening is due to increased basement membrane synthesis. In this study, skin samples from 8 diabetic patients with confirmed capillary basement membrane thickening and 7 non-diabetic controls were used to assess steady state levels of mRNAs coding for several basement components including pro alpha 1(IV) collagen, laminin and fibronectin. Total RNA was extracted from abdominal skin samples and levels of mRNAs coding for the basement membrane components laminin, fibronectin and pro alpha 1(IV) collagen, a fibrillar collagenous protein, pro alpha 1(I) collagen and an intracellular polypeptide, gamma-actin, were determined by dot blot hybridization analysis. While there were no changes of steady state levels of pro alpha 1(I) collagen mRNA and laminin mRNA, a significant reduction was noted in the quantitative recovery of mRNA levels for pro alpha 1(IV) collagen, gamma-actin and fibronectin in total RNA isolated from the skin of diabetic patients. This reduction in levels of mRNAs coding for basement membrane components contrasts with pathological confirmation of an accumulation of endothelial capillary basement membrane in skin from diabetic patients and suggests that basement membrane thickening arises more as a consequence of reduced basement membrane degradation than elevated synthesis of basement membrane components.

Aged↗