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Biomedical subjects

L M Smiley

Publications and source records attributed to L M Smiley.

9 recordsLinked to original sources
PubMed2001

Activation of matrix metalloproteinase dilates and decreases cardiac tensile strength.

Previous studies demonstrated that transition from compensatory pressure overload hypertrophy to decompensatory volume overload heart failure is associated with decreased cardiac tensile strength and activation of matrix metalloproteinase (MMP) in spontaneously hypertensive rat (SHR). To test the hypothesis that in the absence of nitric oxide activation of MMP during cardiac failure causes disruption in the organization of extracellular matrix (ECM) and leads to decrease systolic and diastolic cardiac tensile strength, we employed SHR of 24--32 weeks, which demonstrates significant cardiac hypertrophy and fibrosis. The normotensive Wistar rats (NWR) were used as control. To determine whether cardiac hypertrophy is associated with increased elastinolytic matrix metalloproteinase-2 (MMP-2) activity; quantitative elastin-zymography was performed on cardiac tissue homogenates. The MMP-2 activity was normalized by the levels of actin. The MMP-2/actin ratio was 2.0+/-0.5 in left ventricle (LV) and 1.5+/-0.25 in right ventricle (RV) of SHR(32wks); and 0.5+/-0.25 in LV and 0.25+/-0.12 in RV of NWR(32wks) (P<0.02 when SHR compared with NWR). To measure passive diastolic cardiac function, rings from LV as well as RV through transmyocardial wall from male SHR and NWR of 6--8 weeks and 24--36 weeks were prepared. The LV wall thickness from endocardium to epicardium was 3.75+/-0.25 mm in SHR(32wks) as compared to 2.25+/-0.50 mm in NWR(32wks) (P<0.01). The ring was placed in tissue myobath and length--tension relationships were assessed. The pressure--length relationship was shifted to left in SHR as compared to NWR. The amounts of cardiac elastin and collagen were determined spectrophotometrically by measuring desmosine--isodesmosine and hydroxyproline contents, respectively. A negative correlation between elastic tensile strength and elastin/collagen ratio was elucidated. To create situation analogous to heart failure and MMP activation, we treated cardiac rings with active MMP-2 and length--tension relation was measured. The relationship was shifted to right in both SHR and NWR when compared to their respective untreated groups. The results suggested that activation of MMP led to decreased cardiac tissue tensile strength and may cause systolic and diastolic dysfunction.

Analysis of Variance↗
PubMed1999

Homocyst(e)ine impairs endocardial endothelial function.

Homocyst(e)ine injured vascular endothelium and modulated endothelial-dependent vascular function. Endothelium plays an analogous role in both the vessel and the endocardium. Therefore, we hypothesized that homocyst(e)ine modulated endocardial endothelium (EE) dependent cardiac function. The ex vivo cardiac rings from normal male Wistar-Kyoto rats were prepared. The contractile responses of left and right ventricular rings were measured in an isometric myobath, using different concentrations of CaCl2. The response was higher in the left ventricle than right ventricle and was elevated in endocardium without endothelium. The half effective concentration (EC50) and maximum tension generated by homocyst(e)ine were 10(6) and 5-fold lower than endothelin (ET) and angiotensin II (AII), respectively. However, in endothelial-denuded endocardium, homocyst(e)ine response was significantly increased (p<0.005, compared with intact endothelium) and equal to the response to ET and AII. To determine the physiological significance of ET, AII, homocyst(e)ine, and endothelial nitric oxide in EE function, cardiac rings were pretreated with AII (10(-10) M) or ET (10(-13) M) and then treated with homocyst(e)ine (10(-8) M). Results suggested that at these concentrations AII, ET, or homocyst(e)ine alone had no effect on cardiac contraction. However, in the presence of 10(-10) M AII or 10(-13) M ET, the cardiac contraction to homocyst(e)ine (10(-8) M) was significantly enhanced (p<0.01, compared with without pretreatment) and further increased in the endocardium without endothelium. The pretreatment of cardiac ring with the inhibitor of nitric oxide, Nomega-nitro-L-arginine methyl ester (L-NAME), increased contractile response to homocyst(e)ine. These results suggested that homocyst(e)ine impaired EE-dependent cardiac function and acted synergistically with AII and ET in enhancing the cardiac contraction.

Angiotensin II↗
PubMed1998

Stretch-induced membrane type matrix metalloproteinase and tissue plasminogen activator in cardiac fibroblast cells.

In the normal heart, cardiomyocytes are surrounded by extracellular matrix (ECM) and latent matrix metalloproteinases (MMPs), which are produced primarily by cardiac fibroblasts. An activator of latent MMPs might be induced by ischemic conditions or pressure-induced stretching. To test the hypothesis that an activator of latent MMP is induced in the ischemic heart during transformation of a compensatory hypertrophic response to a decompensatory failing response in cardiac fibroblast cells, we stretched the human cardiac fibroblasts at 25 cycles/min in serum-free or 5% serum culture condition. The membrane type (MT)-MMP activity in stretched cells was measured by zymography and immuno-blot analyses using MT-MMP-2 antibody. The MT-MMP activity was further characterized by transverse-urea gradient (TUG)-zymography. The results suggested that stretch induced a membrane MMP in the fibroblasts that was similar to the MT-MMP induced in ischemic heart. Furthermore, we observed that membrane MMP has distinct mobility in TUG-zymography. To localize the MT-MMP and tissue plasminogen activator (tPA) of latent MMPs, the membrane and cytosol were separated by a method employing a detergent and sedimentation. The MT-MMP and tPA activities of cytosol and membrane fractions were measured by gelatin- and plasminogen-zymography, respectively. Differential-display mRNA analysis was performed on control and stretched cells. In situ immuno-labelling was performed to localize the MT-MMP. The results indicate that induction of MT-MMP occurred in the membrane fractions. The secretion of tPA was elevated in the stretched cells. The MT-MMP activity was inhibited by prior incubation with an antibody generated to membrane MMP. The tPA activity was inhibited by using tPA antibody. These results suggest that, under stretched conditions, neutral transmembrane matrix proteinases are induced in the cardiac fibroblasts. This may lead to activation of adverse ECM remodeling, cardiac dilatation, and failure.

Blotting, Northern↗
PubMed1998

Reduction-oxidation (Redox) and vascular tissue level of homocyst(e)ine in human coronary atherosclerotic lesions and role in extracellular matrix remodeling and vascular tone.

Hyperhomocyst(e)inemia in patients with coronary and peripheral arterial occlusion has been demonstrated by others. Redox-state of homocyst(e)ine causes dysfunction of endothelial cells and promote growth of vascular smooth muscle cells. The role of tissue, protein bound and unbound, oxidative mixed disulfides in the development of fibrous plaque in atherosclerotic lesion is not known. Redox-state around the fibroblasts and vascular smooth muscle cells modulates the expression of extracellular matrix (ECM) components (Tyagi et al. 1996, J Cell Biochem, 61: 139-151). To determine the role of tissue homocystine in fibrotic atherosclerotic plaque development, coronary arteries were isolated from ischemic explanted hearts (n = 10). Apparently normal vascular tissue was obtained from idiopathic cardiomyopathic explanted hearts (n = 10). Tissue extract were prepared from atherosclerotic lesions and from normal arteries devoid of adventitia. Interaction of homocystine with Ellman's reagent (5, 5'-dithio-bis-2-nitro benzoic acid) catalyzed by limiting amount of reducing agent (catalyst) generated change in optical density (OD) at 412 nm in dose dependent fashion. We have generated a standard curve between change at 412 nm and amount of homocystine. The change in OD at 412 nm with increasing amount (0-25 microg) of homocystine demonstrated linearity. The protein-bound oxidized disulfides were precipitated by trichloroacetic acid (TCA) and free-oxidative disulfides in the supernatant were collected. The pathophysiological amount of protein-bound disulfide in atherosclerotic tissue (1.0 +/- 0.2 microg/mg total protein) was 10 times that in normal tissue (0.1 +/- 0.01 microg/mg, p < 0.001). The amount of free oxidative disulfide in atherosclerotic tissue (1.5 +/- 0.3 microg/mg) was 15 times that in normal tissue (0.12 +/- 0.02 microg/mg, p < 0.001). To determine the role of homocystine in ECM expression, ECM collagenase activity in the presence and absence of homocystine was measured by zymography. The effect of homocysteine on collagenase activity was biphasic, increased at < [0.01 mM] and inhibited at > [0.1 mM]. To determine whether homocystine regulates vascular tone, isometric measurements were carried out using normal coronary rings. Results suggested that homocystine induced endothelial-modulated vasoconstriction in coronary vessels. Tissue oxidative disulfides and the homocystine may contribute to the development of fibrotic atherosclerotic lesions and vascular dysfunction.

Arteries↗
PubMed1997

An approach to teaching ethical, legal, and psychosocial aspects of gynecologic oncology in a residency program.

An approach to teaching ethical, legal, and psychosocial issues in gynecologic oncology has been integrated into an obstetrics and gynecology residency program. Team-teaching is used, involving gynecologic oncology faculty members and a medical ethicist with experience teaching in the clinical setting of obstetrics and gynecology. The teaching takes place as part of ongoing teaching rounds in the division of gynecologic oncology. Articles from clinical journals are used to inform and stimulate discussion of clinical ethical, legal, and psychosocial issues. Integrating the teaching of ethical and legal aspects of gynecologic oncology into residency education is challenging, given the competing demands on the residents' time and the need for teaching to be clinically relevant. The program described in this article illustrates that such teaching can be carried out in a manner that covers main issues and has practical value for residents.

Curriculum↗
PubMed1992

Endometrial adenocarcinoma: genetic analysis suggesting heritable site-specific uterine cancer.

UNLABELLED: Genetic factors are clearly integral to the etiology of neoplasia. A cancer family syndrome (Lynch syndrome II) consisting of uterine, colon, and ovarian cancer is recognized, but the heritability of isolated endometrial adenocarcinoma has not otherwise been thoroughly investigated. We have performed pedigree studies in index cases with endometrial adenocarcinoma, using spouses as controls. Preliminary results from 64 probands showed four families in which endometrial adenocarcinoma was diagnosed in at least one first-degree relative of the proband (mother, daughter, sister); none showed relatives with colon or ovarian cancer. In none of the 34 control pedigrees did either a mother or sister have endometrial adenocarcinoma. In four other families, multiple first- and second-degree relatives of probands had adenocarcinoma of the uterus, colon, or ovary, presumably representing a cancer family syndrome (Lynch syndrome II). CONCLUSION: Our preliminary data not only show familial and probably heritable tendencies for endometrial adenocarcinoma, but further suggest that there are at least two distinct forms: (1) the previously described Lynch syndrome II (cancer family syndrome), and (2) a heretofore unemphasized entity characterized by a tendency to endometrial adenocarcinoma alone.

Adenocarcinoma↗
PubMed1991

Prognostic factors in stage IB squamous cervical cancer patients with low risk for recurrence.

About one-half of cervical cancer patients whose tumors recur after radical surgery have negative lymph nodes and clear resection margins. We evaluated 95 patients with squamous cell tumors who underwent radical hysterectomy and pelvic lymphadenectomy between January 1975 and December 1985 and who were thought to be at low risk for recurrence to see whether other clinical or histopathologic factors were predictive of tumor recurrence. Detailed retrospective record review and complete pathology review were accomplished for each case. The 5-year actuarial survival rate was 89%. Nine patients developed recurrent disease (9.5%), of whom eight died. Several clinical features were evaluated as possible prognostic factors: patient age (P = .26), patient race (P = .60), cervical diameter (P = .24), extent of gross cervical involvement (P = .36), and presence of contact bleeding (P = .82). Histopathologic features were examined: depth of invasion (P = .31), number of mitoses (P = .42), character of the tumor-stromal border (P = .15), histologic differentiation (P = .02), lymph-vascular space invasion (P = .56), and width of tumor (P = .23). Depth of invasion did correlate with increasing tumor width (P less than .001). Once node- and margin-positive patients are excluded, differentiation may be the only feature useful in identifying patients at risk for recurrence. Because almost one-half of our patients had poorly differentiated tumors, sole use of this feature as a criterion for adjuvant therapy would have resulted in overtreatment of low-risk patients.

Adult↗
PubMedDate not supplied

Effectiveness and cost benefit of a proposed live cytomegalovirus vaccine in the prevention of congenital disease.

Congenital infection by human cytomegalovirus (CMV) is presently the leading infectious cause of mental retardation and congenital deafness in the United States. Live CMV vaccines in healthy adults have been shown to be safe and to induce immune responses similar to those that occur with natural CMV infection. Yet, only recently has a live CMV vaccine been tested for its protective ability. To evaluate the cost benefit and effectiveness of the proposed live CMV vaccine, we compared the following strategies: routine immunization, selective immunization of those women screened and found to be seronegative, and no immunization. Our results show that, when direct costs alone are considered, routine immunization of healthy women aged 15-25 years is cost beneficial even in populations with CMV seroprevalence as high as 87%. In populations with lower seroprevalence (55%-70%), for every 100,000 women immunized, more than 24 cases of symptomatic congenital CMV infection at birth and a similar number of cases with late sequelae (mainly deafness) would be prevented yearly. Such immunization would result in a net annual saving of $2.5 million.

Adolescent↗