Actin-binding proteins undergo major alterations during the plasma membrane transformation in uterine epithelial cells

BACKGROUND

The apical surface of uterine epithelial cells undergoes a dramatic transformation during early pregnancy. Previous studies have shown that cytoskeletal actin microfilaments are associated with this transformation, but little is known of the role played by actin-binding proteins or which of the many described in other cell types are present in uterine epithelial cells.

METHODS

Immunohistochemical staining using monoclonal antibodies raised against four different actin-binding proteins (alpha-actinin, tropomyosin, gelsolin, and vinculin) was used to study the changing distribution of these proteins in uterine epithelium during early pregnancy in the rat.

RESULTS

Findings indicated the presence of all four of the actin-binding proteins in the uterine epithelium. The distribution of tropomyosin remained unchanged over the period of early pregnancy. Gelsolin and alpha-actinin displayed similarity in distribution. Day 1 showed an apicobasal localisation of reaction product, which by day 6 of pregnancy had concentrated into a thick band across the luminal surface of the cells. Vinculin staining was a diffuse band at the level of the basal plasma membrane at day 1 and became a diffuse faint band across the apical part of the cells on day 6.

CONCLUSIONS

This study confirms the presence of actin-binding proteins in uterine epithelial cells, and these findings are discussed in light of known ultrastructural alterations in the uterine epithelium during early pregnancy. Elucidation of the role of the actin-based cytoskeleton in the uterine epithelium may further our understanding of the dynamics of this unique environment that allows the implantation of a blastocyst.

Leucocyte involvement in lectin-induced deciduomata formation

Intra-uterine injection of the lectin Concanavalin A (ConA) on day 5 of PSP induced a rapid and persistent infiltration of leucocytes into the rat uterine stroma. Although the infiltration of leucocytes was witnessed along the entire length of the uterine horn, areas of stromal oedema, indicative of decidualisation (as indicated by the positive Pontamine Sky Blue reaction), were only associated with regions in which the movement of leucocytes across the uterine epithelium was evident. Epithelial disruption and trauma was frequently noted within these regions. We believe that ConA may initiate decidualisation through indirectly causing epithelial trauma.

Increased lectin binding capacity of trophoblastic cells of late day 5 rat blastocysts

The binding of lectins to the trophoblast of rat blastocysts has been studied using quantitative ultrastructural cytochemistry. Rat blastocysts from early, mid and late d 5 of gestation were stained using biotinylated lectins (Phytolacca americana [Phy am], fucose binding protein [FBP] and soybean agglutinin [SBA]) and a sensitive avidin-ferritin cytochemical method. Electron micrographs of ferritin particles along the membrane were processed to produce images for which grey scale levels could be established and the ferritin particles automatically counted. The ferritin:membrane ratio was then calculated. Increased binding with Phy am (which detects short chain oligosaccharides) was found after midday of d 5, i.e. after hatching. Binding of FBP and SBA did not alter during the period studied. The increased concentration of oligosaccharides on the blastocyst surface membrane after hatching may have important implications for blastocyst attachment to the endometrium.

Plasma membrane transformation: a common response of uterine epithelial cells during the peri-implantation period

The plasma membrane of uterine epithelial cells and its changes during early pregnancy are reviewed. The review first examines morphological alterations in rats and mice and laboratory rodents and finds that similar changes in membrane organization accompany the peri-implantation period: long, thin, regular microvilli are gradually converted into irregular, flattened projections. It is also found however, that in many other species related plasma membrane alterations are seen during early pregnancy. Molecular alterations in the membrane are also examined and although the evidence is so far limited, striking similarities are noted across species. The review also examines some new morphological studies on the alterations in the plasma membrane of uterine epithelial cells during early pregnancy and concludes that a process of plasma membrane transformation may be a common response across species.

Lectin-induced deciduoma formation in the pseudopregnant rat

Decidual cell induction in the pseudopregnant rat was examined in this study using the lectin concanavalin A (ConA). The histochemical binding of the lectin to the uterine cell surface at the time of deciduomatic induction was also studied. ConA was found to induce significant deciduomata (decidual-like tissue) in the uterine horn when injected intraluminally on day 5 of pseudopregnancy (PSP). ConA-induced deciduomata appeared as a series of discrete nodules in the uterine horn, reminiscent of the anatomical appearance of normal embryo implantation sites. Deciduoma induction by ConA was greatly reduced by pre-absorption of the lectin with its competitive sugar. Lectin histochemistry revealed binding of ConA to the cell surface on day 5 of PSP. Pre-absorption of the lectin with its competitive sugar also significantly reduced surface binding of the lectin, and this finding may be correlated with the greatly reduced ability of the pre-absorbed lectin to induce deciduomata. Possible mechanisms for the induction of deciduomata by lectins are considered.

Colonoscopically assisted intracorporeal laparoscopic wedge resection of a benign right colon lesion

We present a case of colonoscopically assisted intracorporeal laparoscopic wedge resection of a benign right colon lesion. The operative technique is described and the rationale discussed with reference to current literature.

Surgical and prosthetic restoration of binaural hearing in an 88-year-old man

We report the restoration of binaural hearing in an 88-year-old man who was experiencing significant communication difficulties. His preoperative air conduction thresholds had revealed a pure-tone average of 55 dB for the left ear and 107 dB for the right, and he was dissatisfied with the benefits provided by his BICROS hearing aid arrangement that had been fitted to his left ear. The combined effects of surgery and a hearing aid offered a 70 to 80 dB improvement for his right ear and restored the communication advantages of binaural hearing.

(+)-Iforrestine: a Novel Heterocyclic Nephrotoxin From Isotropis forrestii

A compound that reproduces the acute renal proximal tubular necrosis associated with ingestion of Isotropis forrestii, by animals, has been isolated from the plant. The novel heterocyclic structure was determined by a single-crystal X-ray diffraction study. The spectroscopic data are presented and rationalized with respect to the assigned structure.

Chromaffin cell heterogeneity of process formation and neuropeptide content under control and nerve growth factor-altered conditions in cultures of chick embryonic adrenal gland

Adrenal glands from embryonic day 11 (E-11) chicks were cryostat-sectioned, and it was determined that tyrosine hydroxylase-like immunoreactive (TLI) cells, somatostatin-like immunoreactive (SLI) cells, and methionine-enkephalin-like immunoreactive (ELI) cells occupied chromaffin regions of the gland. Similar age adrenals were dissociated, and the cells were cultured under serum-free conditions. Cultured TLI cells, ELI cells, and SLI cells were characterized according to cell size, cell number, and neurite formation. ELI and SLI cells composed two largely separate populations, with SLI cells tending to have larger cell areas, to be more numerous, and to be less likely to form neurites than ELI cells. The population of TLI cells, although unique in itself, was diverse and numerous enough to include all or portions of the neuropeptide-immunoreactive populations. Neurites of some cells from each of the above populations were strongly immunoreactive for alpha neurofilament protein, and for NAPA73 neurofilament-associated protein. However, neurites could also be observed in all populations that showed poor immunoreactivity for these cytoskeletal proteins. Exogenously added NGF significantly increased neurite-like process formation among TLI and ELI cells, but not among SLI cells. Reductions in the number of neurite-like processes following treatment with anti-nerve growth factor (NGF) were not significant for any of the populations. However, if shorter and broader process were included, anti-NGF caused a significant reduction in total cell processes among TLI and ELI cells. Anti-NGF inhibition of process formation among ELI cells could be reversed with exogenous NGF. Neither NGF or anti-NGF treatments showed a significant effect on cell numbers among TLI and ELI populations. The implications are that a compound of antigenic and physiological similarity to mouse salivary NGF is made by embryonic chick adrenal cells in culture, but the effects of NGF do not appear to be the same for all neural-crest-derived cells from the adrenal, and greater heterogeneity of phenotypes may exist among chromaffin cells than has previously been accepted. Some questions are also raised concerning the neurite-like nature of processes formed by some chromaffin cells in vitro.

Recurrent re-expansion pulmonary edema

A unique patient is described who experienced two episodes of pulmonary edema following re-expansion of two left pneumothoraces occurring months apart. Successful surgical treatment was carried out at thoracotomy. Factors regarding pathogenesis are discussed.

Laminar flow enclosure-a possible risk to the patient

A retrospective comparison was made between two groups of 50 adult patients who underwent open-heart surgery in an operating suite with two adjacent rooms, one of which was equipped with a laminar flow enclosure. Core and body surface temperatures were measured at 15-min intervals for the 1st h after commencement of surgery. Patients in a laminar flow enclosure showed a significantly greater decrease in core temperature with time. Possible means of counteracting this are suggested.

The Swan-Ganz pulmonary artery catheter. Incidence of complications, with particular reference to ventricular dysrhythmias, and their prevention

A series of seventy-three adult patients undergoing open-heart surgery was studied, in whom a Swan-Ganz pulmonary artery catheter was inserted. The incidence of complications occurring during insertion and use of the catheter was noted, and a controlled trial carried out to determine the efficacy of lignocaine 1 mg/kg iv in preventing ventricular dysrhythmias during passage of the catheter. A significant decrease in dysrhythmia rate was observed. Ways of minimising or preventing other complications are discussed.