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Biomedical subjects

H S Lin

Publications and source records attributed to H S Lin.

At least 145 records · Page 8Linked to original sources
PubMed1979

Reactions of 1,3-bis(2-chloroethyl)-1-nitrosourea and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea in aqueous solution.

Products formed from the reaction of two chloroethylnitrosoureas in neutral aqueous solution have been identified and quantified. Mixture components recovered after a 1-h incubation period accounted for 75--85% of the starting nitrosourea. Approximately 65--85% of the reaction products were formed by an initial cleavage of the nitrosourea to the proposed intermediates 2-chloroethyl azohydroxide and an isocyanate and by subsequent hydrolytic reactions. A minor pathway, 5--10% of products, involves denitrosation of the nitrosourea with oxazoline formation. Stable isotope labeling and mass spectrometry have been used to determine the reaction sequence and product origins. Reaction product identification has been made using high-performance LC isolation and comparison with synthetic material.

Carmustine↗
PubMed1979

The standardization of experimental impact injury to the spinal cord.

The biomechanical criteria for standardization of experimental impact injury to the spinal cord are derived. The theory is verified experimentally using cats. The undesirable effect due to heavy impounders is discussed. A falling mass of 20 gm and a small impounder 5 mm in diameter with a mass of 0.1 gm are recommended, leaving the momentum of the falling body to be controlled for different degrees of trauma.

Animals↗
PubMed1978

The influence of activation, removal or denervation of the pineal on the fine structure of the Leydig cell and seminal vesicle epithelium in golden hamsters.

Fine structural changes of testicular interstitial cells of Leydig and secretory cells of seminal vesicles were studied in golden hamsters under different functional states of the pineal gland. Experiments were performed in the reproductive season (summer months). In the hamsters blinded for 8 weeks the testes and the seminal vesicles were markedly atrophic, and the Leydig cells and the secretory cells of seminal vesicles were extremely involuted. By contrast, both types of cells in the pinealectomized or superior cervical ganglionectomized hamsters exhibited cytological features suggestive of an enhanced secretory activity. This study shows that functional activity of Leydig cells as well as secretory cells of seminal vesicles in the hamster may be depressed or augmented by stimulating of inhibiting the pineal antigonadal function, respectively, without performing hypophysectomy or hormonal administration.

Animals↗
PubMed1978

Peritoneal exudate cells. V. Influence of age, sex, strain and species on the induction and the growth of macrophage colony forming cells.

We investigated the effects of age, sex and strain in the induction of peritoneal exudate colony-forming cells (PE-CFC) in mice. Sex and age (ranging from 3 weeks to 12 months) had no significant effect on the induction of PE-CFC. However, we found significant difference between strains in terms of the number of nucleated cells and the proportion of PE-CFC in exudate cells. When we investigated the mechanisms behind this strain difference, we found that it was due to neither the type of colony-stimulating factor employed in culture, nor the type of stimulants used to induce the exudate, nor the difference in the kinetics of appearance of PE-CFC in the peritoneal cavity. We also studied the induction of PE-CFC in rats and hamsters and the growth of these cells in vitro. Unlike mouse cells, PE-CFC from rats and hamsters could also use media conditioned by cells from other species as a source of colony-stimulating factor.

Age Factors↗
PubMed1978

Mechanical response of the lumbar intervertebral joint under physiological (complex) loading.

Nineteen fresh, intact lumbar intervertebral joints (two vertebrae and the intervening joint) from twelve spines were loaded in a materials testing machine to determine their mechanical behavior. The loads applied were pure axial compression and complex loading conditions simulating physiological states. The measurements made included vertical load deflection, disc bulge, and strains in both the anterior and the lateral aspects of the vertebral body and in one lamina. The results showed that the posterior elements transmit considerable force during quasistatic complex loading, particularly in extension and frontal shear. When a healthy specimen is subjected to complex loading, "yielding or failure" occurs in the vertebral body and not in the annulus fibrosus of the disc.

Aged↗
PubMed1978

Trends in fertility, family size preferences, and family planning practice: Taiwan, 1961-76.

A series of six sample surveys and vital statistics are used to analyze major reproductive trends for 1961-76 in Taiwan. Fertility fell rapidly during 1961-70 as a result of adoption of contraception and rising age at marriage, while there was little change in preferred family size. Between 1970 and 1976 the practice of contraception reached high levels in all social strata, and preferred family size and fertility both declined rapidly. Practice of contraception for spacing births increased considerably after 1970. These changes occurred while many traditional familial values, including strong son preference, persisted. A continuation of the decline in fertility is predicted.

Adolescent↗
PubMed1977

The fine structure of testicular interstitial cells in the adult golden hamster with special reference to seasonal changes.

The fine structure of the testicular interstitium was studied in normal adult golden hamsters sacrificed in the reproductive season (spring and summer) and in the winter. The Leydig cells in the reproductively active testes contain abundant endoplasmic reticulum (ER) and numerous mitochondria. The ER occurs in the form of flattened cisternae and tubules, the former prevailing. The cisternae are extremely extensive and are partly granular and partly agranular, their ends being continuous with the tubluar reticulum. Mitochondria intervening between the cisternae are closely associated with the agranular portions of the latter. Adjacent to the Golgi complex and continuous with the centrosome a unique filamentous body with a dense laminar core is often observed. In the regressive testes, the Leydig cells show a great reduction of cytoplasmic volume and a remarkable decline of the organelles, especially agranular tubules. The possible functional significance of the tubular and cisternal ER with the associated mitochondria is discussed in relation to the biosynthesis of androgens. Macrophages appear to constitute another important population of the interstitial cell clusters.

Androgens↗
PubMed1977

Elastase secretion by peritoneal exudative and alveolar macrophages.

Mouse alveolar macrophages (AM) cultured in the absence of serum secrete an elastolytic enzyme. The elastase from AM resembles the previously described elastase from peritoneal macrophages (PM) in pH optimum and inhibition profile. The macrophage enzymes do not appear to be stored, and with periodic changes in the culture medium, accumulate extracellularly for up to 10 days. Resident PM produce barely detectable levels of extracellular elastase unless given a phagocytic load. Thioglycollate-stimulated peritoneal exudative macrophages (PEM), however, secret easily detectable levels of elastase, which can be further increased with a phagocytic load. Without any additional stimulation, AM secret an elastolytic activity comparable to that of the PEM receiving a phagocytic load, but unlike PM they do not increase elastase secretion after phagocytosis.

Animals↗
PubMed1977

Peritoneal exudate cells. IV. Characterization of colony forming cells.

The adherence, phagocytic activity and buoyant density of mouse peritoneal exudate colony forming units (CFU-PE) were investigated. There was a significant enrichment in the proportion of CFU-PE in the adherent cells population, defined as cells adhering to a plastic surface within 30 minutes of incubation. The phagocytic activity of CFU-PE was studied by incubating exudate cells with iron particles for 45 minutes. The cells were then separated into phagocytic and non-phagocytic cell fractions by passing the incubation mixture through a magnetic field. A significant enrichment of CFU-PE was seen in the phagocytic cell fraction. When exudate cells were fractionated in a Ficoll discontinuous density gradient, more than 88% of CFU-PE were recovered at the 16/18% and 18/20% interfaces. It is concluded that CFU-PE are adherent cells, have strong phagocytic activity and have a buouant density between 1.0562 and 1.0703. When bone marrow cells were studied by these techniques, the committed stem cells for both granulocytes and marcophages (CFU-C) were enriched in both non-adherent cell and non-phagocytic cells populations. In the Ficoll density gradient, CFU-C banded at a heavier density region than CFU-PE.

Animals↗
PubMed1975

Clonal growth of hamster free alveolar cells in soft agar.

Free alveolar cells obtained from healthy unstimulated hamsters were tested for their ability to form colonies in soft agar. Every bronchial washing so far tested contained colon-forming cells. The average plating efficiency was 8.1% (2.4-18.3%). Alveolar colony-forming cells were characterized by having a long initial lag period (4-8 days) and only mononuclear phagocytes were found in the colony. Medium conditioned by baby hamster kidney cells or other cells was required for the initiation and maintenance of their growth. Alveolar cells from normal mice and rats also formed colonies under appropriate culture conditions.

Agar↗
PubMed1975

Proliferation and colony-forming ability of peritoneal exudate cells in liquid culture.

Peritoneal exudate cells, obtained from mice injected with thioglycollate medium and cultured in medium containing L-cell-conditioned medium, will proliferate in an exponential fashion for 18 days with a doubling time of 68 h. After a 2 h pulse of tritiated thymidine, labeled adherent cells increased to a maximum of 22-34% during the 1st and 2nd wk of culture. Increasing the cell concentration from 2 times 10-3 to 2 times 10-5 cells/culture reduced exponential growth to 10 days and the doubling time was increased to 81.6 h. Under these culture conditions, peritoneal exudate cells were shown to form colonies on the surface of culture dishes when plated at low density. The cells within the colony were shown to be macrophages using yeast and antibody-coated sheep erythrocytes as a test for phagocytic function. The plating efficiolonies arose from a single precursor cell. The adherent cell population contains the colony-forming precursors. These precursors can be stimulated to form colonies for at least 2 wk by the addition of conditioned medium to cultures at various times after plating. While very few colony-forming cells could be demonstrated in the unstimulated peritoneal lavage, their numbers begin to increase in the exudate 4 h after injection of thioglycollate medium and reach a maximum by day 3 and then decrease. Isolated colonies may be useful in studying the function of macrophages.

Animals↗
PubMed1975

Fine structural changes in the hamster pineal gland after blinding and superior cervical ganglionectomy.

Pineal glands of male hamsters 8 weeks after removal of both eyes or both superior cervical ganglia and those of untreated animals were studied by electron microscopy. In the blinded hamsters the reproductive organs were remarkably involuted, whereas the pinealocytes enlarged and were characterized by a tremendous hypertrophy of the smooth-surfaced endoplasmic reticulum, in the mesh of which some dense cored vesicles were distributed. In constrast the pinealocytes of ganglionectomized hamsters atrophied and were noted by a large number of lysosomes and sparsity of the agranular reticulum, the testes being significantly larger than the controls. The findings were interpreted to be compatible with the view that the pineal capability of producing antigonadal substance is augmented by blinding and is suppressed by cervical ganglionectomy due to the impairment of normal functioning of the pineal by denervation. It is assumed that the degree of development of the smooth endoplasmic reticulum in the pinealocyte is parallel to, and reflects that of the pineal activity. Probably the membranous organelle is involved in the elaboration of the pineal antigonadal substance.

Animals↗