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S M Yu

Publications and source records attributed to S M Yu.

34 records · Page 2Linked to original sources
PubMed1989

T helper and T suppressor cell reversal during the development of induced rat periapical lesions.

T helper (TH) and T suppressor (TS) cells were enumerated in developing rat periapical lesions in order to identify the cell type associated with the active phase of lesion formation. Experimental pulp exposures were made in all molar teeth of 29 Sprague-Dawley rats, and teeth were left open to the oral environment. On days 15, 20, 30, and 90 after induction, inflammatory cells were isolated from periapical lesions, and T helper (W3/25+), T suppressor (OX8+), and total T cells (W3/13+) were enumerated by reactivity with monoclonal antibodies. During the early, most active phase of lesion development (day 15), TH cells outnumbered TS cells (TH/TS = 1.7). However, by day 20, when lesion expansion had slowed, the TH/TS ratio was reversed (0.9) and remained so for up to 90 days after induction (TH/TS = 0.7). Total T cell numbers did not change over the period of observation. TH cells thus predominated during the active phase of lesion development, whereas TS cells were associated with the chronic phase. This dynamic TH/TS reversal indicates that immune responses which occur within periapical lesions are highly regulated. In addition, the predominance of TH during the active phase of lesion development suggests that TH-mediated activities may be involved in the bone destruction and immune cell activation within periapical lesions.

Animals↗
PubMed1989

An improved flat embedding technique for immunoelectron microscopy.

Immunocytochemical staining has been widely used for localizing various hormonal antigens, protein markers and putative neurotransmitters in tissues. Immunostained sections can be examined light microscopically and specific areas selected for electron microscopic study.

Histological Techniques↗
PubMed1989

An improved micro-incubation well for immunocytochemical staining procedures.

A shallow "micro-incubation well" was made with a piece of the square plastic slide and a glass slide. A circular hole (10-12 mm in diameter) was cut out of the center of the square plastic slide. This plastic slide was then attached to the glass slide with a drop of Epon-Araldite and cured in the 60 degrees C oven for 2 days. One to three small sections of tissue mounted within corresponding circles on an ordinary microscopic slide could be stained when placed upside-down on the well in a moisture chamber. The moisture chamber was modified by a disposable square Petri dish (100 x 15 mm) containing a small amount of water and a shallow slide stage which was made by cutting a half inch rim from the bottom of a round disposable Petri dish (100 x 15 mm). This method provided the following advantages in immunocytochemical staining: (1) an even distribution of micro-amounts of antibody solution for long periods of time, and (2) greatly reduced the cost of the immunostaining technique by using micro-amounts of antibody solution.

Animals↗
PubMed1989

Use of an improved liquid drop retainer for combining immunofluorescence and peroxidase-antiperoxidase techniques.

An improved "liquid drop retainer" was made by gluing a circular cover glass within a selected ceramic ring of a serological ring slide. One to three small sections of tissue mounted within corresponding circles on an ordinary microscopic slide could be immunostained with primary antisera when placed upside-down on the liquid drop retainer. After rinsing in the buffer, the sections were placed upside-down over the liquid drop retainer containing fluorescein isothiocyanate-conjugated immunoglobulin and photomicrographs were taken by placing the inverted sections over the liquid drop retainer. After taking the photomicrographs, the sections were incubated in peroxidase-antiperoxidase complex and placed upside-down over the liquid drop retainer. These liquid drop retainers provided the following advantages in immunocytochemical staining: (1) greatly reduced volumes of antibody solutions to micro-amounts (0.08-0.12 ml); (2) allowed simultaneous localization of different antibodies in adjacent serial sections on the same slide; and (3) allowed immunofluorescence and peroxidase-antiperoxidase techniques to be done on the same section without any damage by immunofluorescence photography before using the peroxidase-antiperoxidase technique.

Animals↗
PubMed1989

[Simultaneous determination of aspirin and phenobarbital in infantile co-phenobarbital powder by dual wavelength K-ratio spectrophotometry].

Aspirin (I) and phenobarbital (II) in infantile co-phenobarbital powder were determined simultaneously using dual wavelength K-ratio spectrophotometry. I and II were analyzed with dual wavelength K-ratio spectrophotometry at 255, 244 and 236 nm. This method showed a mean recovery of 101.3% and a coefficient of variation of 1.6% for (I). The mean recovery and CV of II were 99.21% and 1.90% (n = 6) respectively. The method is simple, rapid and accurate.

Aspirin↗
PubMed1988

Early treatment of young female rats with progesterone delays the aging-associated reproductive decline: a counteraction by estradiol.

We have recently reported that successive treatments of young virgin rats with progesterone (P) implants produce elevated circulating P and consistently low estradiol (E2) concentrations, and subsequently delay the aging-associated reproductive decline. Inasmuch as E2 has been implicated in causing the loss of regular estrous cyclicity in aging rats, the present study examined if the concomitant presence of moderately increased circulating E2 levels could counteract the effects of P implants on reproductive aging. Starting at 3 1/2 mo and continuing to 8 mo of age, regularly cyclic, virgin rats received either s.c. Silastic implants of P (P-implanted), blank Silastic implants (virgin controls), or P + E2 implants (P + E2-implanted) for 3 wk, followed by implant removal for 1 wk. Each of these implant treatments was repeated in the same female rats 5 times. Blood samples were obtained on different days of the estrous cycle from the control group and on Day 11 of successive treatments with P or P + E2 implants for measurements of serum P and E2 values. At 8 1/2 and 10 mo of age, estrous cyclicity of these same virgin rats was again monitored, and 10-mo-old regularly cyclic females from each treatment group were mated with young fertile males to complete term pregnancies. While virgin controls showed cyclic increases in E2 and P secretion during the estrous cycle, P-implanted virgins exhibited consistently low serum E2 and moderately increased P levels during 5 successive treatments. The latter indicates a potent inhibition of ovarian E2 secretion by P implants.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1986

In situ dot blots: quantitation of mRNA in intact cells.

A rapid, simple and reproducible dot blot method is described for quantitating the amounts of specific messages in small numbers of intact cells. The method has been used to accurately determine the number of histone H4 mRNA molecules in growing (approximately 40,000) and in starved (approximately 1600) Tetrahymena thermophila, and to measure the amount of message contributed by an E. coli plasmid containing part of the S10 ribosomal operon. Use of the method is illustrated to optimize in situ hybridization protocols and to measure mRNA amounts in cell lysates. Preliminary studies also indicate that the method can be used to detect mRNA in intact yeast cells.

Endopeptidase K↗
PubMed1986

Use of a monoclonal antibody to classify neurons isolated from the head region of Hydra.

A mouse monoclonal antibody (JD1) to Hydra attenuata using the peroxidase-antiperoxidase (PAP) method revealed unipolar, bipolar, and multipolar sensory and ganglion cells in the head region of H. littoralis. Neurons isolated from macerated hypostomes and tentacles were classified according to the number of their cytoplasmic processes and the position of the cilium, when present, relative to the perikaryon. PAP-stained sensory cells had an apical ciliary cone, whereas ganglion cells did not. Neurons with cytoplasmic processes longer than 50 microns stained faintly, whereas those with processes shorter than 50 microns in length stained mainly dense brown. Unipolar neurons had an oval, crescent, round, or elliptic perikaryon with a single short axon. The perikaryal shape of bipolar neurons varied from round to tall triangular, short triangular, crescent, oval, or elliptic with two oppositely directed symmetric or asymmetric processes. Asymmetric processes were present in a bipolar sensory cell with a long apical cilium typical of gastrodermal sensory cells. One type of bipolar ganglion cell had a short perikaryal cilium. Another type had neurites longer than 50 microns. We found seven morphological variations of multipolar neurons, including one with an apical knob, two with a short perikaryal cilium, two with cytoplasmic loops near the perikaryon, one with perpendicular processes projecting from the major neurites, and one with a branched process longer than 50 microns opposite a tangled mass of neurites.

Animals↗
PubMed1985

Light and electron microscopic localization of a monoclonal antibody in neurons in situ in the head region of Hydra.

A mouse monoclonal antibody to Hydra attenuata was used to demonstrate immunoreactive product in neurons in situ, in both whole mount and sectioned hypostomes and tentacles of H. oligactis and H. littoralis. Immunoreactive cells were concentrated around the mouth and scattered along the length of the tentacles. In the hypostome, nerve cells sent one or more processes orally and the others aborally but the processes were more distinctly stained in H. oligactis. A thin strand of five to six perihypostomal neurons was present close to the hypostome-tentacle junction. In the tentacles, neurons with long processes contacted up to five different batteries of nematocysts. Neural processes were associated with nematocyst batteries in three ways: 1) forming a perikaryal loop to encircle a centrally located stenotele, 2) branching at a distance from the perikaryon to contact a variety of nematocysts, and 3) terminal branching by one or more neurons with contacts on one to several nematocysts within a battery. Immunocytochemical localization of neurons in Hydra by light microscopy was correlated for the first time with electron microscopy. Peroxidase-antiperoxidase (PAP)-positive sensory cells were concentrated around the mouth opening. PAP-positive ganglion cells were predominant in the tentacles. Sensory cells were elongate or spindle-shaped (unipolar), triangular with two oppositely directed processes (bipolar), and multipolar (tripolar or tetrapolar) with one of the processes extending to the epidermal surface. Ganglion cells were either unipolar or bipolar or multipolar, with neurites paralleling the mesoglea and occasionally having processes abut on it.

Animals↗
PubMedDate not supplied

Use of immunoperoxidase and immunogold methods in studying prolactin secretion and application of immunogold labelling for pituitary hormones and neuropeptides.

Two immunocytochemical methods, immunoperoxidase and immunogold (IG), were used in an attempt to study the dynamic process of prolactin release from stimulated rat pituitary mammotrophs. The immunogold method was also used to localize other pituitary hormones including growth hormone, follicle-stimulating hormone, luteinizing hormone, and the neuropeptides substance P, neuropeptide tyrosine, leu-enkephalin, and atrial natriuretic factor in peripheral nerves. Light-microscopic immunoperoxidase staining of prolactin revealed a unique distribution of immunoreactive mammotrophs. Two groups of cells were seen, one centrally located and one forming a narrow peripheral rim on the gland. The two groups were separated by a zone of nonimmunoreactive cells. In addition, the distribution of immunoperoxidase-stained material was not uniform in all mammotrophs. In some, prolactin immunoreactive material was clumped near the nucleus (in the Golgi cisternae); in others it was more diffused within the cytoplasm (but immediately surrounding the cisternae of rough endoplasmic reticulum). After stimulation of mammotrophs, via suckling, prolactin-immunoreactive material was visualized in extracellular spaces. With immunogold methods, prolactin labelling was seen mainly in secretory granules; but some labelling of Golgi cisternae and rough endoplasmic reticulum also occurred. Immunogold labelling revealed that material immunoreactive for leu-enkephalin and atrial natriuretic factor was present in nerve terminals in the rat paracervical ganglion. Material immunoreactive for substance P and neuropeptide tyrosine was present in nerve terminals in the guinea pig heart. Thus, in some situations the immunoperoxidase technique was useful and helped to visualize "grossly" the presence of specific antigens, but it was inadequate for fine ultrastructural localization of these antigens. The immunogold technique was excellent for precise localization of antigens and especially for the detection of colocalization of different antigens. This method can be used in very different structures, such as the adenohypophysis and peripheral nervous tissue, without any modification except for the nature of the antibodies.

Animals↗