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Biomedical subjects

T F Beals

Publications and source records attributed to T F Beals.

At least 37 records · Page 2Linked to original sources
PubMed1991

Effects of transforming growth factor-beta, transforming growth factor-alpha, and other growth factors on renal proximal tubule cells.

Transforming growth factor (TGF)-alpha, epidermal growth factor (EGF), and insulin-like growth factor-1 (IGF-1) addition to quiescent, confluent monolayers of rabbit renal proximal tubule cells in primary culture stimulated [3H]thymidine incorporation. TGF-alpha and EGF promoted a 14-fold rise in thymidine incorporation over control levels with half-maximal responses at 2 x 10(-9) M. IGF-1 only promoted a 4-fold rise in thymidine incorporation compared with control values with a half-maximal response of 10(-8) M. Platelet-derived growth factor alone did not stimulate [3H]thymidine incorporation and did not potentiate the effects of EGF or IGF-1 on DNA synthesis, suggesting that platelet-derived growth factor is neither a competence nor a progression growth factor for renal proximal tubule cells. TGF-beta inhibited both baseline and EGF-stimulated [3H]thymidine incorporation after 48 hours of exposure but enhanced EGF-stimulated DNA synthesis at 24 hours. Morphologic evaluation with phase contrast microscopy, scanning, and transmission electron microscopy demonstrated that TGF-beta promoted a dramatic phenotypic transformation of the epithelial monolayer with migration and adhesion of the cells to form solid clusters of adherent cells. Quantitative morphometry demonstrated that this transformation developed 24 hours after TGF-beta exposure, was nearing completion after 48 hours of TGF-beta treatment, and correlated to TGF-beta related inhibition of EGF-induced DNA synthesis (r = -0.82, p less than 0.01). These results demonstrate that EGF and TGF-alpha are the most potent growth promoters for renal proximal tubule cells. IGF-1 is only a modest growth promoter, whereas platelet-derived growth factor has no effect either as a competence or progressive growth factor. TGF-beta inhibited EGF-induced DNA synthesis but only after observable phenotypic transformation of the cells. The degree of TGF-beta promoted transformation on renal tubule cells was highly correlative to th e antiproliferative effect of TGF-beta, suggesting that similar molecular components which promote this phenotypic transformation may also be critical in the antiproliferative effect of TGF-beta.

Animals↗
PubMed1989

Malignant dermal cylindroma in a patient with multiple dermal cylindromas, trichoepitheliomas, and bilateral dermal analogue tumors of the parotid gland.

A malignant dermal cylindroma of the scalp arose from one of multiple long-standing dermal cylindromas in a 76-year-old man with coexisting trichoepitheliomas and bilateral dermal analogue tumors of the parotid gland. The histologic transition from a benign dermal cylindroma to an anaplastic keratinocytic neoplasm was readily apparent. The malignant dermal cylindroma is a rare neoplasm. To our knowledge, the constellation of benign and malignant dermal cylindromas, multiple trichoepitheliomas, and salivary gland neoplasms has not been previously reported.

Adenoma↗
PubMed1989

Ultrastructural localization of herpes simplex virus RNA by in situ hybridization.

We studied the subcellular localization of virally encoded RNA by pre-embedding in situ hybridization, using colloidal gold as an electron-dense marker. Fibroblasts infected with Herpes simplex virus (HSV) were fixed, permeabilized, then hybridized with a biotinylated HSV DNA probe under conditions favoring DNA-RNA hybrid formation. HSV probe was localized with 5-nm streptavidin-gold conjugates. Transmission electron microscopy revealed 5-nm gold in clusters and singlets within HSV-infected cells. Formalin-fixed cells contained a mean of 4.6 clusters per cytoplasmic profile and 13.2 clusters per nuclear profile. Combined formalin-glutaraldehyde fixation increased the mean number of clusters per cytoplasmic and nuclear profile to 7.2 (57% increase) and 17.5 (33% increase), respectively. Gold clusters were frequently located in regions adjacent to the nuclear envelope but were not bound to viral nucleocapsids or endoplasmic reticulum. Labeling was unaffected by pre-hybridization DNAse treatment of cells. RNAse eliminated 87% of cytoplasmic and 97% of nuclear clusters. These findings indicate that clustered gold particles labeled viral RNA, with probable binding of multiple DNA probe molecules and/or gold particles to RNA strands. This novel pre-embedding technique may be a useful tool for ultrastructural evaluation of virus-host cell interactions.

Cell Nucleus↗
PubMed1989

Bacterial colonization of intravenous catheter materials in vitro and in vivo.

Four different intravenous catheter materials, brands Teflon, Silastic, Vialon, and Tecoflex, were evaluated in vitro for bacterial adherence after 2 and 24 hours' incubation in trypticase soy broth and after 2 hours' incubation in nutrient-free phosphate buffer (pH 7.2). The organisms used were Pseudomonas aeruginosa, Enterobacter aerogenes, Escherichia coli, and Staphylococcus epidermidis. The significant differences in in vitro adherence of the different bacterial species to the various catheters were then evaluated in vivo by intravenous injection of a single bolus of 1 X 10(5) organisms via tail vein of rats with previously placed catheters in their superior venae cavae. There was no association between the in vitro bacterial adherence and the tendency of the in vivo catheters to become colonized. Results of scanning electron microscopy of clean catheters and those removed from the rats showed obvious differences in surface characteristics and in clot adhesion between the catheters. These characteristics did not correlate with bacterial adherence in vitro or colonization in vivo. It is concluded that laboratory studies of bacterial adherence to, physical characteristics of, and thrombogenicity of intravenous catheters do not necessarily translate into resistance to clinical catheter sepsis.

Animals↗
PubMed1988

A cellular model of endothelial cell ischemia.

Endothelial cell dysfunction in ischemia may cause increased capillary permeability. We examined the effect of failing ATP synthesis, a major consequence of ischemia, on microfilaments--important structural determinants of the endothelial cell. Glycolytic and mitochondrial ATP synthesis in bovine pulmonary artery endothelial cells was inhibited by glucose depletion and 650 picomole (pmole) oligomycin/micrograms DNA, respectively. ATP levels were monitored with the luciferase-luciferin assay over a 2-hr time course followed by recovery for 1 hr after removal of the oligomycin and addition of 5.5 mM glucose. ATP levels fell to 83.6 +/- 63.8 pmole/micrograms DNA (n = 11) by 30 min, 26.9 +/- 13.8 pmole/micrograms DNA (n = 11) by 60 min, and 17.2 +/- 3.8 pmole/micrograms DNA (n = 6) by 120 min, whereas control uninjured cells had 541.3 +/- 196.8 pmole/micrograms DNA (n = 6) at 120 min. Fluorescence microscopy of microfilaments stained with rhodamine-phalloidin revealed progressive disassembly and shortening of the microfilaments in greater than 90% of cells over 60 min which correlated with the fall in ATP. Ultrastructural examination revealed that side to side aggregation of microfilaments had occurred over the 120-min time course. Two hours of glucose depletion (305.5 +/- 130.8 pmole ATP/micrograms DNA, n = 6) or oligomycin alone (480.0 +/- 90.1 pmole ATP/micrograms DNA, n = 6) failed to produce the dramatic fall in ATP or the microfilament changes. During cell recovery, there was a rapid reassembly of microfilaments, detected by fluorescence microscopy, which was nearly complete in 85-90% of cells by 45-60 min. ATP levels increased significantly (P = 0.002) to 96.1 +/- 36.8 pmole/micrograms DNA (n = 6) by 30 min. This model should provide insight into the pathogenesis and treatment of the capillary leak seen with ischemia.

Actin Cytoskeleton↗
PubMed1988

Ultrastructural localization of viral nucleic acid by in situ hybridization.

In situ hybridization has become a standard technique in the localization of viral nucleic acids in tissue sections and cytologic preparations at the light microscopic level. We have extended this technique to the electron microscopic level using human cytomegalovirus (CMV) infection in cultured human foreskin fibroblasts, and have shown for the first time that colloidal gold can be used to study intranuclear localization of viral replication. CMV-infected fibroblasts exhibiting early (4-day) and late (18-day) cytopathic effect were fixed in formalin, gently permeabilized with detergent and protease, and hybridized with a biotinylated CMV DNA probe. Hybridized sequences were localized by a pre-embedding technique using streptavidin-conjugated 15 to 20 nm colloidal gold particles. Ultrastructural nuclear and cytoplasmic architecture were well preserved through permeabilization and hybridization steps. Viral DNA was clearly detected in fibroblast nuclei containing nascent and well-formed electron-dense viral inclusions. Gold particles were localized to the periphery of electron-dense nuclear inclusions, occasionally in association with 70 nm nuclear dense bodies, but not with complete viral nucleocapsids. DNA hybridization was abolished by pretreatment of infected cells with DNase. Cross-hybridization of CMV DNA sequences with human DNA or with herpes simplex virus genome was not observed. The ultrastructural findings suggest that CMV DNA replication may occur at the margins of electron-dense regions in maturing viral inclusions, and that viral DNA associated with core dense bodies is available for hybridization with complementary nucleic acid sequences. This technique can be useful in studies of viral pathogenesis.

Cells, Cultured↗
PubMed1988

Immunohistochemical demonstration of cytoplasmic and membrane-associated tumor necrosis factor in murine macrophages.

Using a highly specific rabbit antisera directed against murine tumor necrosis factor (TNF), immunohistochemical localization of this monokine was performed in cultured mouse peritoneal macrophages. Resident macrophages did not express TNF even after stimulus with lipopolysaccharide (LPS). In contrast, 12% of macrophages elicited with Freund's adjuvant stained positively and up to 60% were positive after LPS stimulation. Analysis of the kinetics of expression revealed that maximal staining occurred from 1-3 hours after stimulus with disappearance of staining by 12 hours. Both a membrane and cytoplasmic pattern of staining could be demonstrated. The presence of plasma membrane TNF was confirmed by scanning electron microscopy. Northern blot analysis and bioassay revealed that the kinetics of TNF mRNA synthesis corresponded to the appearance of the protein while its disappearance corresponded to the appearance of TNF in the supernate. Thus, TNF synthesis and secretion could be histochemically demonstrated. These findings support the notion that TNF production is a characteristic of activated macrophages and that such cells display membrane-associated TNF at least transiently after stimulation.

Animals↗
PubMed1988

ATP and microfilaments in cellular oxidant injury.

Oxidant injury produces dramatic changes in cytoskeletal organization and cell shape. ATP synthetic pathways are major targets of oxidant injury resulting in rapid depletion of cellular ATP following oxidant exposure. The relation of ATP depletion to the changes in microfilament organization seen following H2O2 exposure were examined in the P388D1 cell line. Three hours of glucose depletion alone resulted in a decline in cellular ATP levels to less than 10% of controls, which was comparable to ATP levels in cells 30 to 60 minutes after exposure to 5 mM H2O2 in the presence of glucose. Adherent cells stained with rhodamine phalloidin, a probe specific for polymerized (F) actin, revealed a progressive shortening of microfilaments into globular aggregates within cells depleted of glucose over 3 hours, a pattern similar to earlier observations of H2O2-injured cells after 1 hour. The changes in cellular ATP associated with glucose depletion or H2O2 exposure were then correlated with G actin content measured by the DNAse 1 inhibition assay. No real differences in G actin content as a percentage of total actin were seen in P388D1 cells following 3 hours of glucose depletion or 30 to 60 minutes after exposure to 5 mM H2O2. But 2 to 3 hours after exposure to H2O2 there was a progressive decrease in G actin as a percentage of total actin within the cells. Transmission electron microscopy of cells depleted of glucose for 3 h or 1 hour after exposure to H2O2 revealed the presence of side-to-side aggregates or bundles of microfilaments within the cells. These observations suggest that declining levels of ATP either from metabolic inhibition or H2O2 injury are correlated with the fragmentation and shortening of microfilaments into aggregates. No net change in monomeric or polymeric actin was necessary for this to occur. However, at later time points after H2O2 exposure some actin assembly did occur.

Actin Cytoskeleton↗
PubMed1987

Effect of angioplasty-induced endothelial denudation compared with medial injury on regional coronary blood flow.

To determine the effect of angioplasty-induced arterial injury on regional coronary blood flow, resting and postocclusion reactive hyperemic flows were measured in the left anterior descending (LAD) and circumflex (LCx) coronary arteries of 32 dogs after one of four interventions in the LAD with a balloon angioplasty catheter: group A, no injury; group B, endothelial denudation; group C, medial injury; group D, pretreatment with 325 mg of aspirin 2 hr before medial injury. Resting flows did not change in any group. In group C, hyperemic flow decreased in both the LAD and LCx by 15% to 20% (p less than .001) over 30 to 90 min, suggesting that a circulating substance changed coronary resistance. Histologic and ultrastructural studies of the LADs demonstrated an intact endothelial cell layer in group A, endothelial disruption with a few adherent platelets in group B, medial injury with a dense layer of adherent platelets in group C, and medial injury with a few adherent platelets in group D. Thus endothelial denudation results in relatively mild platelet deposition and no change in resting or hyperemic coronary blood flow. In contrast, medial injury results in relatively marked platelet deposition and a significant decrease in hyperemic flow, both of which are prevented by platelet inhibition with aspirin.

Angioplasty, Balloon↗
PubMed1986

Small cell carcinoma of the larynx: results of therapy.

Primary small cell carcinoma of the larynx is a rare malignancy with a dismal prognosis. A survey of the long-term follow-up from reported cases of small cell carcinoma of the larynx and a review of the recent experience with this tumor at the University of Michigan Hospitals was undertaken to determine if newer treatment approaches incorporating adjuvant chemotherapy were associated with prolonged survival. Median survival for those patients receiving adjuvant chemotherapy was 19 months compared to 11 months for patients treated with surgery and/or radiation therapy alone. Among patients treated initially with primary radiation therapy and adjuvant chemotherapy median survival was 55 months, which was significantly longer than any other treatment regimen (P = 0.02). Systemic chemotherapy and therapeutic irradiation appears to offer the least disabling and most efficacious form of current therapy.

Aged↗
PubMed1986

The scintigraphic localization of mineralocorticoid-producing adrenocortical carcinoma.

I-131-6 beta-iodomethylnorcholesterol (NP-59) was used to localize mineralocorticoid-secreting adrenocortical carcinomas in two patients and functioning metastases in a third patient studied after the removal of the primary tumor. The presence of sufficient NP-59 activity within these lesions for discernable imaging is unusual and would not have been expected based on previous experience with other functioning and nonfunctioning carcinomas of the adrenal cortex. These cases serve to illustrate the variable spectrum of iodocholesterol uptake into adrenocortical malignancies and suggest that scintigraphic studies, preoperatively for localization and postoperatively to confirm the presence of recurrence or metastases, might be useful to identify and characterize these rare neoplasms.

19-Iodocholesterol↗
PubMed1986

Leu-M1-positive small cell carcinoma.

A case of metastatic small cell carcinoma of the lung is reported; initially, on the basis of morphology, phenotyping with monoclonal antibodies, and cytochemistry, the carcinoma was interpreted as a hematopoietic neoplasm. Noncohesive blast-like cells observed in bone marrow and lymph node biopsy specimens stained with the monoclonal antibodies Leu-M1 and OKIa1 and were also positive for nonspecific esterase and acid phosphatase. Although these findings suggested a monocytic origin for the neoplastic cells, further analysis, including ultrastructural examination, disclosed metastatic small cell carcinoma. This case illustrates the need for caution in the interpretation of staining with monoclonal antibodies because of the potentially wide range of normal and abnormal cells and tissues that may react with monoclonal reagents.

Adult↗
PubMed1986

Acromegaly due to ectopic growth hormone (GH)-releasing hormone (GHRH) production: dynamic studies of GH and ectopic GHRH secretion.

Dynamic studies of GH and GH-releasing hormone (GHRH) secretion were performed in a man with a GHRH-producing carcinoid tumor and acromegaly. Insulin hypoglycemia stimulated and metoclopramide inhibited both GH and GHRH acutely. Bromocriptine suppressed GH both acutely and chronically without altering circulating GHRH levels and also blunted the GH response to exogenous GHRH. TRH acutely stimulated GH, but not GHRH, secretion, and iv bolus doses of synthetic GHRH-(1-40) stimulated GH release acutely. Somatostatin infusion decreased both GH and GHRH concentrations and blunted the GH responses to TRH and GHRH-(1-40). We conclude that prolonged exposure of the pituitary gland to high concentrations of GHRH is associated with chronic GH hypersecretion and may be accompanied by a preserved acute GH response to exogenous GHRH; a paradoxical response of GH to TRH may be mediated at the pituitary level, consequent to prolonged pituitary exposure to GHRH; bromocriptine suppression of GH in acromegaly is due to a direct pituitary effect of the drug; and somatostatin inhibits both ectopic GHRH secretion as well as GH responsiveness to GHRH in vivo. Since GH secretory responses in patients with somatotroph adenomas are similar to those in this patient, augmented GHRH secretion may play a role in development of the "classic" form of acromegaly.

Acromegaly↗
PubMed1986

Continual skin peeling syndrome. An electron microscopic study.

We encountered a patient with continual skin peeling syndrome, a rare disorder in which generalized, noninflammatory exfoliation of the stratum corneum occurs. Although scaling occurred spontaneously in our patient, he was also able to manually peel sheets of skin without bleeding or pain. Histologically, there was separation of corneocytes above the granular cell layer. Ultrastructural examination revealed an unusual type of intracellular cleavage, in which the plasma membrane of the "peeling" cell remained firmly adherent to the underlying cell while the upper part of the cell exfoliated. Unique intercellular electron-dense globular deposits were localized to the stratum corneum.

Biopsy↗
PubMed1985

Substrate-dependent differences in growth and biological properties of fibroblasts and epithelial cells grown in microcarrier culture.

Normal diploid human fibroblasts and first passage monkey kidney epithelial cells were examined for growth and metabolic activity on microcarriers made from glass and on microcarriers made from DEAE-dextran. The cells grew to a higher density (cells cm2 of surface area) on the glass microcarriers made from glass and on microcarriers made from DEAE-dextran. The cells grew to a higher density (cells/cm2 of surface area) on the glass microcarriers than they did on the DEAE-dextran microcarriers and morphological differences were observed between the cells growing on the two substrates. On the DEAE-dextran microcarriers, the cells were much more resistant to protease-mediated detachment than were the cells on the glass microcarriers. In these respects, the cells grown on the glass microcarriers were similar to cells grown in conventional monolayer culture. Interestingly, the cells grown on the DEAE-dextran microcarriers expressed higher levels of proteolytic enzyme activity than the cells grown on the glass microcarriers. Substrate-dependent differences in prostaglandin production also occurred--both in unstimulated cells and in cells stimulated with 12-0-tetradecanoyl phorbol acetate. The unstimulated cells on the glass microcarriers produced slightly higher levels of three different prostaglandins than did the cells on the DEAE-dextran microcarriers. However, after stimulation the levels were much higher in the DEAE-dextran microcarrier cultures than in the glass microcarrier cultures. In contrast to these results, there was no significant, substrate-dependent difference in the production of infectious herpes simplex virus. Taken together, these findings suggest that when commercially-useful cells such as normal fibroblasts and epithelial cells are grown in large quantities on microcarriers, the nature of the substrate may have a profound effect on the growth and physiology of the cells. They also suggest that when microcarriers are used, unexpected results based on preliminary work in conventional monolayer culture may be obtained.

Animals↗
PubMed1985

Transbronchial fine needle aspiration of bronchogenic cysts.

Transbronchial fine needle aspiration (TBFNA) was used to confirm the diagnosis of bronchogenic cyst in two asymptomatic patients with mediastinal masses who declined surgical exploration. Both masses were located subcarinally but differed in computed tomographic density (7 and 59 Hounsfield units). Aspirate cytology demonstrated predominately bronchial columnar epithelial cells in mucus, without the lymphocytes and polymorphonuclear leukocytes normally seen in intrabronchial secretions. The denser cyst additionally contained some alveolar macrophages with ingested surfactant. While benignity cannot be absolutely assured, it is corroborated by serial evaluation of these patients, which has revealed no interval change in symptoms or roentgenographic size for two and three years, respectively. Under selected circumstances, it appears that TBFNA can be used to extend bronchoscopic diagnosis to benign mediastinal masses if the cytologic features of such aspirates are unique.

Biopsy, Needle↗