RAPID DETERMINATION OF CELL NUMBERS IN THE HUMAN TESTIS BY PHASE-CONTRAST CYTOMETRY: A NEW TECHNIQUE FOR ESTIMATING RATES OF SPERM PRODUCTION AND GERMINAL CELL ATTRITION AND FOR ASSESSING ABSOLUTE ABUNDANCE OF SERTOLI CELLS

1982 ◽  
Vol 383 (1 The Cell Biol) ◽  
pp. 464-465
Author(s):  
Larry Johnson ◽  
William B. Neaves
Keyword(s):  
Sertoli Cells ◽  
Phase Contrast ◽  
Rapid Determination ◽  
Human Testis ◽  
Germinal Cell ◽  
Sperm Production ◽  
Absolute Abundance ◽  
Cell Numbers ◽  
A New Technique

The “calcium clamp”: effect of constant hypocalcemia on parathyroid hormone secretion

1981 ◽  
Vol 240 (6) ◽  
pp. E649-E655
Author(s):  
J. Fox ◽  
H. Heath
Keyword(s):  
Parathyroid Hormone ◽  
Feedback Control ◽  
Rapid Determination ◽  
Hormone Secretion ◽  
Conscious Dogs ◽  
Half Time ◽  
Experimental Animals ◽  
A New Technique ◽  
Ipth Concentration

This report describes acute studies of parathyroid hormone (PTH) secretion and metabolism in conscious dogs, performed with a new technique, the “calcium clamp.” Bolus injections and graded infusions of either calcium (Ca) or EGTA, respectively, increase or decrease plasma Ca to desired levels in 1–2 min; rapid determination of plasma Ca permits feedback control of the infusion rates to maintain the desired Ca concentration for prolonged periods. Using this technique, we have examined the effect in five dogs of a sustained (1 h) decrease in plasma Ca from 9.6 to 7.6 mg/dl on the secretion of PTH. Plasma immunoreactive PTH (IPTH) concentration in precaval blood increased within 1 min, peaked at 4–10 min (greater than 5 times control), but thereafter declined gradually to 57% of the maximum at 60 min, despite ongoing and constant hypocalcemia. Abrupt restoration of normocalcemia caused IPTH levels to decrease with an apparent half-time of 3.0 +/- 0.3 min (mean +/- SE). Thus, external feedback-regulated control of plasma Ca is possible in experimental animals. IPTH concentrations decline from the maximum during constant hypocalcemia, a new observation that suggests that PTH secretion and/or metabolism are altered progressively by the hypocalcemia.

scholarly journals Immunolocalization of Sperm Protein 17 in Human Testis and Ejaculated Spermatozoa

2003 ◽  
Vol 51 (9) ◽  
pp. 1245-1248 ◽  
Author(s):  
Fabio Grizzi ◽  
Maurizio Chiriva–Internati, ◽  
Barbara Franceschini ◽  
Paul L. Hermonat ◽  
Giuseppe Soda ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Sertoli Cells ◽  
Leydig Cells ◽  
Interstitial Cells ◽  
Human Testis ◽  
Germinal Cell ◽  
Sperm Protein ◽  
Primary Function ◽  
Mammalian Protein ◽  
Sperm Protein 17

Sperm protein 17 (Sp17) is a highly conserved mammalian protein whose primary function is still poorly understood. Immunohistochemistry (IHC) in the human testis reveals the presence of Sp17 in some spermatocytes and abundantly in spermatids. All spermatogonia, Sertoli cells, and Leydig cells appear to be immunonegative for Sp17, whereas some interstitial cells are immunopositive. IHC recognized two distinct populations (immunopositive or not for Sp17) in the ejaculated spermatozoa. Although it will be necessary to clarify why some ejaculated spermatozoa do not contain Sp17, its distribution suggests that this protein may be associated with some phases of germinal cell differentiation.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Weak Beam Imaging and Diffraction Studies of Stacking Faults in Silicon

1976 ◽  
Vol 34 ◽  
pp. 590-591
Author(s):  
T. Y. Tan ◽  
W. K. Tice
Keyword(s):  
Fast Neutron ◽  
Rapid Determination ◽  
Stacking Faults ◽  
Imaging Method ◽  
Large Reduction ◽  
Dislocation Loops ◽  
Fringe Spacing ◽  
Weak Beam ◽  
Kinematical Theory

In studying ion implanted semiconductors and fast neutron irradiated metals, the need for characterizing small dislocation loops having diameters of a few hundred angstrom units usually arises. The weak beam imaging method is a powerful technique for analyzing these loops. Because of the large reduction in stacking fault (SF) fringe spacing at large sg, this method allows for a rapid determination of whether the loop is faulted, and, hence, whether it is a perfect or a Frank partial loop. This method was first used by Bicknell to image small faulted loops in boron implanted silicon. He explained the fringe spacing by kinematical theory, i.e., ≃l/(Sg) in the fault fringe in depth oscillation. The fault image contrast formation mechanism is, however, really more complicated.

Methods for rapid determination of pecan (Carya illinoensis) seed viability

2017 ◽  
Vol 45 (2) ◽  
pp. 455-464
Author(s):  
T.T. Xue ◽  
J. Liu ◽  
Y.B. Shen ◽  
G.Q. Liu
Keyword(s):  
Rapid Determination ◽  
Seed Viability ◽  
Carya Illinoensis
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