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Biomedical subjects

H L Lin

Publications and source records attributed to H L Lin.

53 records · Page 3Linked to original sources
PubMed1983

Some of the alpha-NH2-acetylated beta-endorphin-like material in rat and monkey pituitary and brain is acetylated alpha- and beta-endorphin.

There are several studies demonstrating the existence of alpha-NH2-acetylated (N-Ac) forms of beta-endorphin in the intermediate lobe of several species (1,4,6). These include N-Ac-beta-endorphin (1-31), N-Ac-beta-endorphin (1-27) and N-Ac-beta-endorphin (1-26). The existence of N-acetylation of brain beta-endorphin is more controversial (5,6). Using molecular sieving, HPLC, and several radioimmunoassays, either directed at the midportion of beta-endorphin or at only N-acetylated opioids, we have studied brain multiple forms (cf. Akil, 1982). We have noted that little or no acetylation of beta-endorphin-sized material occurs in hypothalamus, and a small amount of N-acetylation appears to take place in the midbrain and the medulla. These results will be described in detail elsewhere (Akil et al., in preparation), but point the fact that processing of beta-endorphin (1-31) in brain is different than either lobe, with the production of beta-endorphin (1-27) and beta-endorphin (1-26) being more predominant in brain terminal areas than in the neuro-intermediate lobe. In the course of these experiments we noted the existence of a smaller-sized material which reacted with our N-acetyl-beta-endorphin antibody. The following study describes the partial characterization of this material as N-Ac-alpha- and N-Ac-beta-endorphin (i.e., the N-acetylated forms of beta-endorphin (1-17) and beta-endorphin (1-16).

Animals↗
PubMed1980

Left ventricular free wall and intraventricular pressure-sarcomere length distributions.

Sarcomere lengths were measured after pentobarbital anesthesia at five sites through the wall of the formaldehyde solution-fixed cadmium-arrested closed-chest rat left ventricle. Sections (250 micron) were cut from endocardium to epicardium with a freezing microtome. Selected sections were sonified, mixed with a gelatin-water solution, and placed on a glass slide. Sarcomere lengths were measured with an optical microscope at five sites through the wall. Sarcomere lengths progressively increased from section I (endocardium site) to section III (middle site) and IV. Sarcomere lengths were again shorter in section V (epicardium site). There was a progressive increase in sarcomere lengths with increasing intraventricular pressures. Sarcomere lengths did not significantly exceed optimum length.

Animals↗
PubMed1977

Functional morphology of the pressure- and the volume-hypertrophied rat heart.

We studied hearts in which hypertrophy was caused by both pressure and volume overload. Pressure hypertrophy was induced by an aortic constriction; volume hypertrophy was induced by an iron-copper deficiency (anemia). The ventricular weight was increased by 34% in the pressure-hypertrophied hearts at the end of 6 weeks. The ventricular weight was increased by 54% in the volume-hypertrophied hearts at the end of 3 months. A potassium arrest-formalin fixation technique was used to produce a "diastole-like" ventricle. In the pressure-hypertrophied ventricle, the ventricular wall thickness and external radii were significantly increased, whereas the valve-to-apex distance and internal radii remained unchanged. We also found that in the volume-hypertrophied ventricle there was an increase in the valve-to-apex distance, external radii, internal radii, and wall thickness. Although external and internal dimensions increased, the ventricular shape did not change significantly in the volume-hypertrophied ventricle.

Animals↗
PubMed1976

Drug inhibition of ecto-ATPase and of phagocytosis in leukocytes.

Substituted phenothiazines and tricyclic antidepressants which inhibited the ecto-ATPase in leukocytes also markedly decreased the phagocytic activity of these cells. In affecting either the enzyme or phagocytosis the order of potency of the drugs was similar. Various other CNS drugs were ineffective. The results suggest possible involvement of ecto-ATPase in the phagocytic process, and indicate adverse effects of the aforelisted drugs on the host defense system against foreign materials, including microbes.

Adenosine Triphosphatases↗
PubMed1975

Papillary muscle shortening in the intact dog; a cinderadiographic study of tranquilized dogs in the upright position.

Shortening of the anterior papillary muscle of the left ventricle was demonstrated in six intact, tranquilized dogs. Two small metal markers that had been surgically implanted 3-50 months earlier were cineradiographically photographed during approximately ten sequential cardiac cycles in each of two orthogonal positions. Distances between markers were plotted for successive frames. The resulting curves were used to obtain maximum velocities of papillary muscle shortening and lengthening: 1.08 plus or minus 0.29 muscle lengths/sec and 1.39 plus or minus 0.48 muscle lengths/sec, respectively. From the two orthogonal planes, the average maximum spatial distance and the average minimum spatial distance between the markers were calculated. The mean percent shortening of 22.8 plus or minus 6.5% was surprisingly large: it approximated the distance from the foot to the peak of the ascending limb of the myocardial length-tension curve derived from isolated muscle studies. Mechanical studies on isolated papillary muscle have consistently shown reduced shortening with increasing loads. Since the in vivo dog papillary muscle has been reported to be under considerable tension during systole, there appears to be some contradiction between the degree of shortening found in the present study and the shortening observed in isolated papillary muscle studies.

Animals↗
PubMedDate not supplied

The pattern of sarcomere lengths through the left ventricular free wall: differences between open and closed-chest rats.

Sarcomere lengths were measured with an optical microscope at five sites through the free wall of the open-chest rat left ventricle. After pentobarbital anesthesia the hearts were arrested with 5 mM cadmium chloride and 0.9% saline and fixed with formaldehyde solution. Serial sections (250 microns thick) were cut from endocardium to epicardium with a freezing microtome. Selected sections were sonified, mixed with a gelatin-water solution, and placed on a glass slide. There was a progressive increase in mean sarcomere lengths with increasing intraventricular pressures though the sarcomeres did not significantly exceed their optimum length. There was a distinct and statistically significant difference in the pattern of sarcomere lengths through the ventricular wall between our previous closed-chest study and the present open-chest study. In this open-chest animals, there was an almost linear pattern of increasing sarcomere lengths from endocardium to epicardium over the range of semiphysiologic diastolic intraventricular pressures (6, 12, and 24 cm H2O -- 0.59, 1.18, 2.35 kPa). These results appear to caution against extrapolations on ventricular function derived from open chest studies to the normal physiologic conditions.

Animals↗
PubMedDate not supplied

Fiber bundle direction in the mammalian heart. An extension of the "nested shells" model.

The orientation of the muscle fiber bundles within the mammalian left ventricle was examined in a variety of mammals. The hearts were arrested in situ in animals with an intact thorax by means of an isotonic K+ solution perfused via the aorta and coronaries. The hearts were then fixed by formalin perfusion through the same vessels and the hearts embedded in gelatin. Serial sections were prepared perpendicular to the Apex-Valve axis. On close examination, the muscle fibers show the change in orientation from endocardium to epicardium previously described by others. In addition, the clefts and voids of the inner one-third to inner one-half of the left ventricular wall add another dimension to the fiber direction: the fiber bundles appear to take a curving course from the middle of the wall to the endocardial surface. This pattern was visible in all studied hearts. Speculations are made on the significance of this anatomic arrangement.

Animals↗
PubMedDate not supplied

Left ventricular shape-luminal pressure relationship. An open-chest study.

Left ventricular dimensions were measured in Cd2+ arrested (presumably diastolic), open-chest rats. Aortic pressure was maintained at 137 cm H2O (100 mm Hg) and left-ventricular (luminal) pressures were established and maintained at their chosen values, each by means of reservoir systems. The selected left-ventricular pressures were chosen to be within or to even broaden the range of conceivable diastolic pressures (-3 to 48 cm H2O). After in situ fixation with 4% formaldehyde and gelatin embedding, the hearts were serially sectioned in the apex base direction to obtain information at 11 levels (10, 20, . . . 90, 100%). Tracings of selected sections were made along the edge of the left ventricular lumen and the pericardial surface. Volumes, surface areas, and mean external and internal radii of the left ventricle were derived. To quantify the circularity of sections a form factor (FF) was introduced (FF = 1 for a circular cross-section and less than one for other shapes). Ventricular lengths, radial dimensions, endocardial and epicardial surface areas, and total and luminal volumes increased with the increasing intraventricular pressures; as expected, the wall simultaneously thinned. Though its appearance was altered by the wall thinning, the curving muscle fascicular pattern was present over the entire pressure range examined. Endocardial surface areas increased more than did the epicardial surface areas. The endocardial FF value increased (more circular) at each section level as the pressure increased. The epicardial FF relationship was apparently constant (0.798 +/- 0.014) for all section levels from 10% through 90%, regardless of luminal pressure. These results, when taken in conjunction with the results of our previous published studies, prompted the following speculation. The wall of the diastolic ventricle is a fluid-filled chamber with intramyocardial pressures that may be higher than ventricular pressures.

Animals↗
PubMedDate not supplied

Diagnosis of congenital hypothyroidism from human anagen scalp hair by infrared microspectroscopy.

A highly efficient Fourier transform infrared (FT-IR) microscopy was used to determine the biophysical structure of anagen scalp hair roots of neonates suffering from congenital hypothyroidism (CH) due to ectopic thyroid. The present results indicate that the lower composition near 1,053 cm(-1) (also assigned to the aromatic iodide stretching band) in the infrared (IR) spectra of the hair roots for CH patients was directly associated with the lower serum level of T4 and fT4, and the elevated TSH levels determined by RIA method. This strongly implies the lower evidence of the aromatic iodide stretching band in the IR spectra of hair roots. These findings suggest that FT-IR microscopy has the potential to become a good diagnostic tool and that hair can be useful as a genetic marker.

Cell Cycle↗
PubMedDate not supplied

Submicromolar paclitaxel induces apoptosis in human gastric cancer cells at early G1 phase.

Paclitaxel induced apoptosis has been reported in many cancer cell lines, but the relationship between G2/M phase arrest and apoptosis is not clear. We have reported that low dose (10 nM) paclitaxel induced apoptosis in gastric cancer cells without G2/M phase arrest. In this study, SC-M1 gastric cancer cells were synchronized at early G1, late G1, S and G2/M phases by staurosporine, mimosine, hydroxyurea and berberine, respectively. We have found that paclitaxel could not induce apoptosis of gastric cancer cells in late G1, S and G2/M phases; however, paclitaxel induced apoptosis in the early G1 phase. Our results suggest that cells arrested at G2/M phase by paclitaxel eventually entered the early G1 phase then proceeded to apoptosis.

Antineoplastic Agents, Phytogenic↗