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Biomedical subjects

M C Poole

Publications and source records attributed to M C Poole.

9 recordsLinked to original sources
PubMed1992

An image processing/stereological analysis system for transmission electron microscopy.

This study examines the feasibility of combining computer image digitization, image enhancement, and point counting stereological techniques to quantify video images from transmission electron microscopes (TEM). The essential hardware consists of an IBM PC/AT, a Matrox imaging board, a digitizing tablet, a high resolution black and white monitor, and a portable mass storage device. In addition a video camera must be mounted to the TEM. The software is written in three modules which have numerous routines for image acquisition, enhancement, and quantification. Quantification is achieved by selecting an electronic lattice and superimposing it on the cell image. A cursor is moved on the lattice (via the digitizing tablet) and the points are entered into a spreadsheet. One of the major limitations of the system was the reduced resolution inherent in the current hardware. However, sampling experiments showed that one could compensate for the reduced resolution by increasing the magnification of the digitized images, and the stereological values from digitized images compared favorably to those from electron micrographs. Furthermore, the system proved advantageous by eliminating the usual darkroom work, and in enhancing low contrast tissue. In spite of several hardware limitations, the concept of quantifying computer digitized TEM images appears promising.

Animals↗
PubMed1991

Alteration of the mammotroph Golgi complex by the dopamine agonist 2 Br-alpha-ergocryptine (CB-154) in ovariectomized estrogen primed rats.

The present study examined the acute effects of 2 Br-alpha-ergocryptine (CB-154, a dopamine agonist) on mammotroph organelles during prolactin (PRL) suppression. Ovariectomized estrogen-primed rats received a single injection (sc) of 0.5 mg CB-154 and the animals were killed at intervals following injection. The anterior pituitary glands were fixed for electron microscopy and immunocytochemistry was used to confirm mammotroph identification. Serum PRL levels were determined by RIA. Following CB-154 administration, serum PRL was significantly (P less than 0.05) reduced within 15 minutes and was suppressed (P less than 0.01) to ovariectomized levels at 2 and 6 hours. A stereological analysis of mammotrophs in the central regions of the anterior pituitary showed that the Golgi complex volume was significantly (P less than 0.05) reduced at 2 hours after CB-154 treatment. However, the Golgi complex volume had recovered by 6 hours post CB-154 injection. In addition, the volumes of the mammotroph cells, the mature secretory granules, and the secondary lysosomes had significantly increased by 6 hours. There were no significant changes in any of the organelles following CB-154 in the mammotrophs from the peripheral regions of the gland. These studies show that the Golgi complex is especially susceptible to acute morphological changes induced by bromocryptine and that the mammotrophs in the central regions are more responsive to CB-154 than those in the peripheral regions.

Animals↗
PubMed1984

Glucose affects in vitro maturation of fetal rat islets.

Fetal pancreatic islets (21.5 days old) were cultured in RPMI 1640 containing either 2.8 or 11.1 mM glucose for 7 days. After the 7-day culture period, islets cultured in 2.8 mM glucose demonstrated a minimal first phase of insulin secretion in response to acute glucose stimulation, whereas islets cultured in 11.1 mM glucose demonstrated a biphasic insulin secretory pattern. Islets cultured in 11.1 mM glucose initiated insulin secretion at 4.4 +/- 0.1 mM glucose and plateaued at 11.6 mM glucose when exposed to a linear gradient. In addition, culture in 11.1 mM glucose increased DNA content (P less than 0.01) and [3H]thymidine incorporation (P less than 0.05) in fetal islets. However, ultrastructural morphometric analysis indicated that the actual number of beta-cells within islets cultured in either 2.8 or 11.1 mM glucose did not increase. The insulin contents of islets cultured in 2.8 and 11.1 mM glucose were 0.46 +/- 0.06 and 1.14 +/- 0.10 mU/islet, respectively. During subsequent glucose stimulation, islets cultured in 2.8 and 11.1 mM glucose released 3% and 5.6% of their total insulin content, respectively. Ultrastructural morphometric analysis indicated that 11.1 mM glucose stimulated an increase in the volume of individual beta-cells, i.e. hypertrophy. The hypertrophy of beta-cells within islets cultured in 11.1 mM glucose resulted in a concomitant increase in islet volume. Finally, the hypertrophy of beta-cells within islets cultured in 11.1 mM glucose was a result of increased volumes of mitochondria, secretory granules, and, to the greatest extent, endoplasmic reticulum. These findings indicate that glucose is a potent factor in the maturation of cultured fetal rat islets.

Animals↗
PubMed1984

Effects of growth hormone on the in vitro maturation of fetal islets.

To study the effects of growth hormone (GH) on the in vitro maturation of fetal islets, the fetal islets were cultured for 7 days in RPMI 1640 containing 10% fetal bovine serum and 11.1 mM glucose with or without GH. Culture with 1 microgram/ml of bovine GH increased the DNA content of the islets and [3H]thymidine incorporation into DNA confirming results of other investigators. In addition, however, the insulin secretory dynamics and ultrastructural morphometrics were investigated. It was found that GH-treated islets demonstrated increased insulin release during acute glucose stimulation when expressed as microunits per islet per minute. However, when insulin release during acute glucose stimulation was expressed as microunits per microgram of DNA per minute to compensate for the increased DNA content of GH-treated islets, no change in insulin release was observed compared to control islets. When GH-treated islets were perifused with a linear glucose gradient, the insulin secretory response was suppressed as indicated by changes in the threshold level, plateau level, and half-maximal response. Ultrastructural morphometric data showed that the average beta-cell volume in control and GH-treated islets was the same, eliminating the possibility that beta-cell hypertrophy occurred. Similarly, the nuclear volumes of the beta cells in control and GH-treated islets remained unchanged. This finding coupled with the observed increased DNA content and [3H]thymidine incorporation suggests that GH functions by increasing cell multiplication within the islets and not by inducing polyploidy. Finally, the volumes of cytoplasmic organelles in control and GH-treated islets were the same indicating that cytodifferentiation did not occur.

Animals↗
PubMed1983

A computer program using a nested analysis of variance in morphometric sampling.

The quality of the sample set is absolutely essential in a morphometric analysis. In this paper a computer program is described which uses a nested analysis of variance in defining the sample. The program denotes those levels of the sampling protocol at which additional sampling should be performed to reduce the variance within the sample set. Furthermore, the program is written for use on a microcomputer which allows it to be used routinely in monitoring a sample set.

Analysis of Variance↗
PubMed1982

Cellular distribution within the rat adenohypophysis: a morphometric study.

A morphometric analysis of the cell types within the adenohypophysis of the female rat was conducted with an emphasis on regional variations. Type I and type II gonadotropes and corticotropes had the largest volumes, mammotropes and somatotropes were of medium size, and thyrotropes and chromophobes were the smallest cells. There was no regional variation in the volumes of the respective cell types. Somatotropes and mammotropes were most numerous, followed by the gonadotropes, chromophobes, corticotropes, and thyrotropes. There was no significant regional localization of the somatotropes, mammotropes, corticotropes, and thyrotropes. Gonadotropes were best defined as two populations with type I cells being localized in the central regions and type II cells being distributed throughout the gland. Chromophobes were the only cells with a significant distribution in the anterior regions and were most numerous in the anterior peripheral regions. These fine-structural morphometric findings are discussed in relation to other studies of the adenohypophysis that utilize immunocytochemistry.

Animals↗
PubMed1979

A computer program for the morphometric analysis of cell profiles.

A computer program which yields values for the volumes, surface areas, and volume/surface area ratios of cell profiles is described for use on a desktop calculator (minicomputer). This program uses standard morphometric procedures, and incorporates data obtained from electron micrographs at two levels of sampling. The main program yields values for the 'average cell volume' at the tissue level of sampling. Two options at the cellular level of sampling are also included which yield values for the volumes, surface areas and volume/surface area ratios for the organelles. The first option allows an analysis of 'whole cells' containing equatorial profiles through the nucleus, while the second option permits a 'fractional' approach using segments of the cells. Finally, some of the advantages of the two options are discussed.

Cell Count↗