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F J Leu

Publications and source records attributed to F J Leu.

10 recordsLinked to original sources
PubMed1992

Microencapsulated pancreatic islets: a pathologic study.

Dog pancreatic islets isolated by an enzymatic digestion method were encapsulated in an alginate-poly L-lysine-alginate membrane. These microencapsulated pancreatic islets were cultured in vitro to study their ability of insulin secretion. Portions of these in vitro-cultured microencapsulated pancreatic islets were taken out for a viability dye exclusion study as well as for pathologic studies to correlate them with insulin secretion ability. We found that there was a strong correlation between them. Good insulin-secreting microcapsules showed well-preserved cell membranes and beta-cell granules. An in vitro culture for one to two days in RPMI-1640 made the islets more stable, the cellular surface became smoother and the beta-granules were in better shape. The microencapsulated pancreatic islets were also injected into the peritoneum of streptozotocin-induced diabetic CDF1 mice. Blood glucose levels dropped and stayed low for up to 60 days. But, when non-encapsulated dog pancreatic islets were used, the blood glucose levels remained low for only about 14 days. A small portion of the injected microcapsules were washed out at specific times for pathologic study. Up to 28 days after injection, only a few of the injected microcapsules showed pericapsular cellular infiltrate. However, after 56 days, most of the microcapsules showed dense pericapsular cellular infiltrate. Immunohistochemical analysis of these infiltrates showed that the majority of cells were fibroblasts and macrophages. Most of the cells located in the inner portion of the infiltrate were fibroblasts, while the macrophages were located mainly on the outer portion. Both scanning and transmission electron microscopy showed that the surface of the microcapsule outer wall was much smoother than the inner wall. The size of the microcapsules was approximately 0.6-0.8 mm and the thickness of the wall measured around 10 nm. The smaller the microcapsule is, the less chance there is of rupture with release of the xenographic islets. Once the wall of the transplanted microcapsules was ruptured, the inner surface showed more increased inflammatory cell and fibroblast infiltration than the outer surface.

Animals↗
PubMed1991

Detection of acute myocardial infarction by evaluation of ultrasonic gray levels in dogs.

The study tested whether an experimental myocardial infarction can be detected from two-dimensional echocardiograms (2DE) by analysis of regional gray levels. The mid-left anterior descending coronary artery was ligated for 3 hours in 14 dogs (group 1) and for 5 hours in 6 dogs (group 2). 2DE were performed before, and after 3 and 5 hours of coronary artery ligation. The ultrasonic amplitude of the control and infarcted regions were obtained from digitized 2DE in the short axis view, at the mid-papillary muscle level. The mean gray levels (+/- SD) of the control and infarcted regions were compared during end-diastolic stop frames. After sacrifice, the hearts were cut into 1 cm thick slices and stained with 1% triphenyl tetrazolium chloride (TTC) solution. The myocardium was then studied by light microscopy. Computerized tomographic scans were also obtained in vitro from 3 hearts of both groups. There was no difference in mean gray levels of the control region during the experiments. However, in the region of wall motion abnormality (area of infarction), the mean gray levels increased from 49.9 +/- 3.5 (before ligation) to 62.0 +/- 7.4 (after 3 hours of ligation, p less than 0.005) in 10 group 1 dogs, but no differences were seen in mean gray levels (49.6 +/- 3.8 vs 50.4 +/- 4.0) in those without a myocardial infarction in 4 group 1 dogs; gray levels also increased from 50.4 +/- 2.9 (before ligation) to 58.6 +/- 6.1 (after 3 hours of ligation, p less than 0.05) and to 65.0 +/- 4.2 (after 5 hours of ligation, p less than 0.005) in group 2 dogs. The area of left ventricular asynergy corresponded precisely to the area of myocardial infarction, determined by both TTC staining and the computerized tomographic scans. The light microscopy of the infarcted area also demonstrated interstitial edema and polymorphonuclear cell infiltration.

Animals↗
PubMed1991

Extracellular matrix alteration in chronic hepatitis.

We used immunofluorescence and immunohistochemical PAP methods on 22 paraffin-embedded liver tissue specimens for observation and analysis of the distribution of extracellular matrix (ECM) elements in chronic hepatitis and cirrhosis. Our study revealed that in CLH there was only mild increases of types III, V collagen and fibronectin in spotty necrosis areas. In CPH, types III, V collagen and fibronectin revealed mild to moderate increase in portal area and lobular sinusoid. In CAH, moderate to marked increases of types III, V collagen and fibronectin and mild increase of type IV collagen in portal area, sinusoid lining, piecemeal necrosis and fibroseptum were found. Types I, IV collagen in fibroseptum were also noted. Some periportal hepatocytes showed abundant intracellular fibronectin. In cirrhosis, cases expressed similar finding to CAH except much more type IV collagen deposition. In addition, the basement membrane components including type IV collagen and laminin were found in the "capillarization" of periportal sinusoids in fibrotic liver tissue. In areas of piecemeal necrosis, the hepatocytes, single or assembled in "rosettes", were underlined by linear deposits of laminin and type IV collagen. Our study revealed that, histologically, the ECMs distribution of CAH is similar to that of cirrhosis but could be clearly distinguished from CPH and CLH. The prominent changes of ECMs, especially the basement membrane components, in case of CAH and cirrhosis are consistent with the fact that ECM may play a central role in liver function impairment and fibrogenesis.

Adult↗
PubMed1990

Detection of human papillomavirus DNA in human cervical lesions by tissue in situ nucleic acid hybridization.

Cervical cancer is one of the most common female cancers in Taiwan. Certain types of human papillomavirus (HPV) are frequently detected in the epithelial precancerous and cancerous lesions of the cervix. By the use of tissue in situ hybridization, we investigated the relationship of various types of HPV (group I, HPV-6 & 11, group II, HPV-16 & 18, group III, HPV-31, 33 & 35) with cervical condyloma, carcinoma as well as precancerous lesions. Group I HPV DNAs were mainly found in cervical condylomatous lesions (2/2) of the cervix and cervical intraepithelial neoplasia I (CIN I) (2/4), but were only occasionally found in CIN II (1/4), CIN III (1/9) or non-keratinized squamous cell carcinoma (1/15). HPV DNAs of groups II and III were mainly detected in lesions of CIN III (5/9) and invasive squamous cell carcinoma (large cell, keratinized type: 4/7; large cell, non-keratinized type: 11/15). HPV DNA sequences were invariably detectable only in the cell nuclei of condyloma or dysplastic epithelium or invasive carcinoma. However, they could not only be detected in the upper layer dysplastic cells and koilocytes but also in the well and poorly differentiated cervical cancer cells. The distribution of HPV DNA positive cells in the carcinomas fell into four different patterns: (1) upper zone and non-invasive regions of the carcinoma (11/22, 50%), (2) basal zone and invasive regions (2/22, 9%), (3) randomly scattered (7/22, 32%), and (4) extensively distributed over the whole tumor lesions (2/22, 9%). Thus, our results are consistent with a strong correlation between the presence of HPV-16, 18, 31, 33 and 35 and malignant conversion of cervical epithelial cells.

Condylomata Acuminata↗
PubMed1988

Protease treatment combined with immunohistochemistry reveals heterogeneity of normal and neoplastic basement membranes.

Heterogeneity of normal tissue and neoplastic basement membranes was investigated immunohistochemically with monoclonal antibodies and polyclonal antisera to laminin and collagen type IV. Cryostat sections of normal and neoplastic human tissues were digested with bacterial protease or trypsin. The duration of digestion and the concentration of enzyme were varied to determine whether laminin and collagen type IV could be removed differentially from basement membranes from distinct anatomic sites. After digestion, the residual antigenicity of glycoprotein was assessed immunohistochemically. Laminin could be removed more easily from all tissues than could collagen IV, and also much more easily from malignant tumors than from benign tumors or normal tissues. On the basis of susceptibility to proteolytic digestion, basement membranes from normal human tissues were classified as susceptible (e.g., heart and smooth muscle of gastrointestinal tract and uterus), moderately resistant (e.g., nerve, skeletal muscle, epithelial basement membrane of skin, smooth muscle of arteries), and very resistant (e.g., glomerulus). Differential susceptibility to proteolytic digestion most likely reflects quantitative and possibly also qualitative differences in the composition of basement membranes.

Basement Membrane↗
PubMed1988

Microencapsulation [corrected] of tumor cells and assay for selecting anticancer drugs.

A microencapsulation of living tumor cells by an improved membrane and droplet forming technique was established in our laboratory. This semipermeable microencapsulating membrane was impermeable to serum albumins (M.W. 66,000 or 45,000) and human hemoglobin (M.W. 64,000), but permitted passage of low molecular weight substances (alpha-Lactalbumin, or Trypsinogen; M.W. 14,200 or 24,000). The in vivo results showed that microencapsulated tumor cell lines (KB, human oral epidermoid cell; P-388 lymphocytic leukemia; GBM 8401/TSGH, glioma) and human colorectal carcinoma cells grew and proliferated exponentially within twenty days. The in vivo growth exhibited better than that in vitro. Histological and morphological findings of these four different kinds of tumor cells are similar to those of original tumor cells. Treatment of the microencapsulated tumor cells (MTC) with cytotoxic drugs (adriamycin, 5-fluorouracil and cyclophosphamide) in vitro showed no significant difference in percent inhibition (p greater than 0.05) between the encapsulated and non-encapsulated cells. The in vivo data indicated that different anti-cancer drugs had different inhibition effects. The results showed that the MTC model was useful for screening an appropriate cytotoxic drug and could be applied to clinical medicine in the near future.

Animals↗
PubMed1987

Immunohistochemical heterogeneity of alpha-tubulin in human epithelia revealed with monoclonal antibodies.

Four monoclonal antibodies raised to alpha subunit of pig brain tubulin (TU-01, TU-02, TU-03, TU-04) were used to study immunohistochemical heterogeneity of alpha tubulin in human epithelia. Selective reactivity was detected in the skin and trachea/bronchi, whereas all other epithelia investigated reacted uniformly with all four monoclonal antibodies. In the skin TU-01 reacted very strongly with all layers except the basal layer; TU-02 reacted strongly with granular layer and was unreactive or only weakly reactive with others; TU-03 reacted very strongly with basal layer and weakly to moderately with superficial layers; TU-04 reacted strongly with the granular layer of epidermis and was unreactive with other layers. In the trachea and major bronchi TU-01 reacted with the entire epithelial layer; TU-02 reacted only with superficial layer; TU-03 reacted with superficial and basal layer; TU-04 reacted only with superficial layer. Different staining patterns obtained with these four monoclonal antibodies indicate that there is immunohistochemical heterogeneity of alpha tubulin in some but not all normal human epithelia.

Antibodies, Monoclonal↗
PubMed1986

Heterogeneity of basement membranes of the human genitourinary tract revealed by sequential immunofluorescence staining with monoclonal antibodies to laminin.

We used monoclonal antibodies specific for human laminin to analyze immunohistochemically the heterogeneity of the basement membranes in various parts of the genitourinary tract. By indirect immunofluorescence microscopy we show that antibody 3H11 reacts with all epithelial basement membranes in the kidneys, testes, epididymis, prostate, uterus, oviduct, and ovary, as well as the smooth muscle cells, blood vessels, and nerves. Antibody 4E10 reacted with most epithelial basement membranes in these organs but was unreactive with the basement membranes of peripheral glomerular capillary loops and the basement membranes of the oviductal mucosa, seminiferous tubules, straight tubules, and rete testis. Hilar seminiferous tubules were reactive with 4E10. In contrast to 3H11, which reacted with all vascular, subendothelial, and muscular basement membranes, 4E10 reacted only with the subendothelial basement membrane of capillaries and veins. The difference in the distribution of epitopes could be demonstrated in tissue sections sequentially reacted with two monoclonal antibodies, but only if the antibody of restricted reactivity (4E10) was used first. These data show that the heterogeneous expression of distinct epitopes of laminin in basement membranes can be demonstrated in the same tissue section by sequential staining. This heterogeneity of basement membranes most likely reflects conformational differences in the expression of epitopes on the laminin molecule in various anatomic structures.

Adult↗