Biomedical subjects

P Kaufmann

Publications and source records attributed to P Kaufmann.

At least 55 records · Page 3Linked to original sources

PubMed2001

A longitudinal study of quantitative uterine blood flow with the use of color power angiography in appropriate for gestational age pregnancies.

OBJECTIVE: The purpose of this study was to examine longitudinally changes in quantified blood volume flow in the uterine arteries during pregnancy with the use of color power angiography. STUDY DESIGN: Color power angiography was used to quantify volume flow in the uterine arteries of 57 women with singleton uncomplicated pregnancies between 20 and 38 weeks' gestation. Comparisons were made between blood flow in the 2 arteries in relation to the location of the placenta. Linear regression models were used to estimate gestational age derived volumetric changes in these vessels. RESULTS: The diameter of the uterine arteries increased from 2.6 mm (SD, 0.2 mm) at 20 weeks to 4.8 mm (SD, 0.7 mm) at 38 weeks of gestation. The total uterine artery blood volume flow increased from 513 mL/min (SD, 127 mL/min) at 20 weeks to 970 mL/min (SD, 193 mL/min) at 38 weeks. The rate of increase was maximum between 20 and 24 weeks (39 mL/min per week). The laterality of the placenta significantly affected the diameter and blood volume flow in each uterine artery. The diameters on the ipsilateral side were significantly greater (by 10.8% +/- 2.4%) than the diameters on the contralateral side at all gestations (P < .05). Similarly, blood volume flow was significantly greater (by 17.8% +/- 2.2%) on the ipsilateral side at all gestations (P < .05). There were, however, no statistically significant differences between the vessel diameters and blood volume flow in those cases in which the placenta was central. Total uterine artery volume flow per kilogram of estimated fetal weight decreased from 1544 mL/kg per minute at 20 weeks to 296 mL/kg per minute at 38 weeks of gestation. CONCLUSION: Total quantified uterine artery blood volume flow increases while blood flow per kilogram of fetal weight decreases with gestation. Blood volume flow in the ipsilateral artery to the placenta was significantly higher than that in the contralateral artery. Calculating total uterine artery volume flow by doubling the blood flow from 1 artery (as was previously done) may therefore either result in an over or underestimation, depending on the relationship between the vessel and the laterality of the placenta. Color power angiography is a simple noninvasive tool for determining uterine artery blood volume flow.

Angiography↗

PubMed2001

Vocal fold paresis of Charcot-Marie-Tooth disease.

No cohesive overview of vocal fold abnormalities associated with Charcot-Marie-Tooth disease (CMT) has been presented in the literature. This study examines a patient in depth and compares the findings with those of published reports to characterize the features of vocal fold paresis in CMT. The affected patient was investigated with nerve conduction testing, laryngeal electromyography, endoscopy, and laryngeal sensory testing. Ten published cases were reviewed for similarities and differences. Vocal fold paresis has been observed in 11 CMT patients ranging in age from 8 to 80 years. Two cases have occurred in the context of CMT type 1, and 9 in CMT type 2. Seven of the 11 cases (64%) were clearly bilateral; only 2 of the 7 cases (29%) required tracheotomy, and both were in children. The electromyographic findings were typical of reinnervation. Sensory findings were present, but did not represent significant disability in the 1 patient so studied. We conclude that CMT does not spare the cranial nerves, as has been previously thought. Furthermore, vocal fold paresis is not restricted to CMT type 2 and should not be considered a hallmark of that category. The available evidence suggests that the neural deficit evolves gradually, may exhibit partial recovery, and often escapes notice for a time. Vocal fold abnormalities are most often bilateral. Because the deficit is generally well tolerated in adults, many cases have probably been overlooked, and no conclusion regarding incidence is possible. Nevertheless, the potential for airway compromise exists, especially in children. Respiratory complaints of CMT patients should be thoroughly investigated.

Adult↗

PubMed2000

Cytogenetic and DNA-fingerprint characterization of choriocarcinoma cell lines and a trophoblast/choriocarcinoma cell hybrid.

We report the successful fusion of human choriocarcinoma cells with normal human trophoblast cells to a choriocarcinoma/trophoblast hybrid. The hybrid cells ACH1P were derived from fusion of primary male trophoblast cells with the HGPRT-defective choriocarcinoma cell line AC1-1. The karyotypes of the parental choriocarcinoma cell line JEG-3, its HGPRT-defective mutant clones AC1-1, AC1-5, and AC1-9, and the choriocarcinoma/trophoblast hybrid ACH1P are presented, together with a detailed characterization of the AC1-specific chromosomal marker add(X)(q26) using conventional cytogenetic banding techniques and multiplex-fluorescence in situ hybridization (M-FISH). To our knowledge, this is the first report of a stably proliferating human cell hybrid of trophoblastic origin, providing a unique cell culture model to study trophoblast-related invasion and its underlying genetic mechanisms.

Cell Fusion↗

PubMed2000

Expression of the imprinted genes MEST/Mest in human and murine placenta suggests a role in angiogenesis.

In the mouse fetus, Mest is widely expressed in mesoderm derived tissues. In separate studies in mice and in humans, it has been shown to be maternally imprinted, that is, only the paternally inherited allele is active. Here, we show that starting with implantation, Mest is also expressed in maternal decidua of the mouse and in placenta of both humans and mice. Expression in murine decidua was restricted to endothelial cells. After Day 7, expression in the decidua gradually decreased. Mest-specific RT-PCR and restriction fragment length variant (RFLV) analysis of decidualized endometrium isolated from (M. musculus x M. spretus)F1 females showed that only the paternally derived Mest allele was activated in the decidual endothelium. In the mouse extraembryonic tissues, Mest transcripts were detected in derivatives of extraembryonic mesoderm only. Here, hemangioblast precursor cells and endothelial cells were positive. At all developmental stages of the mouse, trophoblast-derived cells were clearly devoid of Mest transcripts. In the human placenta MEST transcripts were also detected in hemangioblast precursor cells, however, MEST was also expressed in villous and invasive cytotrophoblast. In a human choriocarcinoma/trophoblastic tumour grown in a nude mouse, human MEST was expressed in the tumour cells, whereas murine Mest was expressed in endothelia of the murine capillaries. The expression pattern exhibited by both Mest and MEST in extraembryonic tissues during development and during formation of choriocarcinoma/trophoblast tumour suggests a functional role of the MEST proteins related to oncofetal angiogenesis. Dev Dyn 2000;217:1-10.

Animals↗

PubMed2000

Development of the placental villous tree and its consequences for fetal growth.

Co-ordinated development of the fetal villous tree of the placenta is necessary for continued fetal growth and well-being. Before fetal viability, blood vessel development within the developing immature intermediate villi (IIV) is characterized by branching angiogenesis, such that the placenta expands to produce 10-16 generations of stem villi. Once fetal viability is attained, a developmental switch occurs to form large numbers of gas-exchanging terminal villi (TV) by non-branching angiogenesis in mature intermediate villi (MIV). Several growth factors, including vascular endothelial growth factor (VEGF), placenta growth factor (PlGF), angiopoietins, and angiostatins are produced within the villi and act locally, via their receptors, to control angiogenesis. Their relative contributions to placental vascular development are not fully understood at the present time. Severe early-onset intrauterine growth restriction (IUGR) is characterized by absent/reversed end-diastolic flow velocity (ARED) in the umbilical arteries, leading to fetal hypoxia, acidosis and a substantial rise in perinatal mortality and morbidity. The placentas from such cases show a deficit in peripheral villous development, which may be perpetuated by the effects of oxygen (delivered by maternal blood into the intervillous space) upon VEGF-directed angiogenesis, the so-called 'placental hyperoxia' theory of villous maldevelopment. Trophoblast apoptosis is a significant feature of early-onset IUGR and may explain poor flow-independent transfer of nutrients to the fetus. Finally, since transgenic mouse studies highlight the importance of trophoblast-derived transcription factors for placental villous (labyrinth) development, it is possible that the villous trophoblast controls the orderly development of the underlying mesoderm and blood vessels into the fetal villi.

Animals↗

PubMed2000

The human placenta is encircled by a ring of smooth muscle cells.

The marginal zone of the human term placenta was studied by transmission electron microscopy and immunohistochemistry using antibodies against cytoskeletal filaments, extracellular matrix molecules and endothelial markers. The marginal sinus of the intervillous space is separated from the chorionic and basal plates by a layer of cells expressing vimentin, desmin, alpha- and gamma-smooth muscle actins, and smooth muscle myosin. Also ultrastructurally, these cells share all features with smooth muscle cells. This muscular ring is continuous with the media of uteroplacental veins entering the marginal sinus. In the basal plate the muscle cells may extend far into the central parts of the placenta. The muscular ring is separated from the intervillous space by a layer of endothelial cells. They are continuous with the maternal endothelium of the marginal uteroplacental veins. Moreover this endothelium covers neighbouring parts of the chorionic and basal plates, locally extending to the surfaces of large stem villi. The data suggest (1) that the marginal zone of the intervillous space ('marginal sinus') represents the dilated and merged parts of uteroplacental veins and (2) that lateral growth of the human placenta partly takes place by expansion into the uteroplacental veins. The functional importance of this muscular ring remains unknown.

Actins↗

PubMed2000

Pregnancy-induced de-differentiation of media smooth muscle cells in uteroplacental arteries of the guinea pig is reversible after delivery.

The majority media of smooth muscle cells of uteroplacental arteries of the guinea pig is not destroyed during trophoblast invasion. Rather, most of these cells de-differentiate during pregnancy-induced arterial dilatation, forming a population of mesenchyme-like myoblasts ready to reconstitute the media after birth. We have studied the re-differentiation of these cells after delivery by means of transmission electron microscopy and immunohistochemistry using antibodies against a panel of cytoskeletal proteins. The data reveal that post partum re-differentiation of the media myoblasts starts immediately after birth where some of the invasive trophoblast cells are still present. The process of re-differentiation is completed at day 8 after parturition. Post partum re-differentiation can be subdivided into two steps: until day 5 after parturition, the central parts of the media are reconstituted out of the reservoir of vimentin-positive myoblasts by stepwise acquisition of desmin, alpha-smooth muscle actin, gamma-smooth muscle actin and smooth muscle myosin. Only thereafter the same re-differentiation takes place in the peripheral parts of the media. On the ultrastructural level immunohistochemical re-expression of cytoskeletal proteins is accompanied by reconstitution of the intracellular contractile apparatus. The data support our earlier notion that the majority of media smooth muscle cells in the guinea pig uterus does not degenerate during trophoblast-invasion but rather de-differentiate temporarily.

Animals↗

PubMed2000

Distensible transtrophoblastic channels in the rat placenta.

Paracellular pathways in the haemotrichorial placenta of the rat were studied by electron microscopy using lanthanum hydroxide as an electron dense marker. Near term placentae were dually perfused in situ, adding lanthanum to the fetal perfusate. In some placentae outflow pressure on the fetal side was elevated (between 10 and 25 cm H(2)O) to promote filtration of fluid in a fetomaternal direction. Under normal pressure conditions lanthanum particles lined the subendothelial spaces and tubular structures in the inner, syncytial layer of trophoblast. Further penetration of lanthanum into the tubules was blocked by coarse lanthanum aggregates. Elevated fetal hydrostatic pressure resulted in a fluid shift across the placenta (filtration rate 50+/-16 per cent of fetal arterial inflow rate), distending the tubules in the inner trophoblast layer. Lanthanum particles gradually appeared in tubular structures in the middle (syncytial) layer and in the lateral intercellular spaces in the outer (cellular) layer. Finally lanthanum reached the maternal surface of the trophoblast. These pressure effects were only partially reversible. When the fetal pressure was returned to control values, some distension of the tubules persisted and the entire length of the paracellular pathways remained accessible to lanthanum. It is concluded that the placental barrier in the rat contains pressure dependent paracellular pathways connecting the maternal and fetal extracellular compartments.

Animals↗

PubMed2000

Cognitive consequences and central nervous system injury following treatment for childhood leukemia.

OBJECTIVES: To determine the relationship between membrane damage and intellectual and academic abilities in children with acute lymphoblastic leukemia (ALL) and pilot test a math intervention for children with ALL who were affected. DATA SOURCES: Research studies and review articles. CONCLUSIONS: Despite the prophylactic central nervous system (CNS) treatment for long-term disease-free survival, many children with ALL subsequently experience declines in intellectual and academic skills. IMPLICATIONS FOR NURSING PRACTICE: Improving academic abilities in children who have received CNS treatment is of high priority and may have longlasting implications on quality of life.

Analysis of Variance↗

PubMed2000

High level of cholesterol increases coronary vasomotor tone during exercise.

BACKGROUND: Coronary vasomotor tone plays an important role in the regulation of myocardial perfusion and influences ischemic threshold significantly. Endothelial dysfunction occurs in the presence of coronary risk factors and is closely linked to the development of atherosclerosis affecting myocardial perfusion and decreasing ischemic threshold. OBJECTIVE: To study the effect of hypercholesterolemia on coronary vasomotor tone in normal and stenotic coronary arteries at rest and during exercise. PATIENTS AND METHODS: In total 48 patients were included in the present analysis. Patients were divided into two groups according to the actual levels of serum cholesterol: 18 patients had normal (mean 181 +/- 28 mg%; group 1) and 30 had elevated (mean 263 +/- 46 mg%; group 2) levels of serum cholesterol according to the 4S criteria with a cutoff level of 213 mg% (5.5 mmol/l). Coronary vasomotor tone at rest and during supine bicycle exercise was calculated by dividing mean aortic pressure by radius of coronary vessel obtained using biplanar quantitative coronary angiography. A normal as well as a stenotic vessel segment in each patient were studied. RESULTS: Normal vessel segments in patients with normal levels of cholesterol (group 1) exhibited no exercise-induced change in coronary vascular tone (+3%, NS), whereas a significant increase in tone (+24%, P < 0.01 versus rest) occurred in those with high levels of cholesterol (group 2). In contrast, stenotic segments in members of both groups exhibited an increase in vascular tone irrespective of the actual level of serum cholesterol. CONCLUSIONS: Hypercholesterolemia causes a pathologic increase in coronary vasomotor tone of angiographically normal vessel segments during exercise. A similar pathologic response occurs in stenotic arteries, but this is independent of the actual level of serum cholesterol. These findings suggest that hypercholesterolemia influences vasomotor tone of the nonstenosed coronary arteries in patients with coronary artery disease probably through the occurrence of endothelial dysfunction.

Cholesterol↗

PubMed1999

[Pseudomonas pneumonia--an important differential pulmonary infiltration diagnosis in AIDS].

Bacterial pneumonias are the most common pulmonary complication in HIV-infected patients. Up to now, H. influenzae and S. pneumoniae have been described as the most important germs. Within a period of 4 years we diagnosed 15 cases of pneumonia caused by P. aeruginosa. All patients were in HIV stage C3; 3F, 12M; median age 34 (24-54) years; median CD4 count 10 (0-130) microliters. Except for 3 nosocomial pneumonias, all others were community-acquired. Only 3 patients had neutropenia < 1000/microliter; 7 were intravenous drug abusers. Morphologically there were 6 cases of abscess pneumonia, in 3 of which pleural drainage was necessary because of pyopneumothorax. 4 patients showed bilateral infiltrates that could not be differentiated from those of P. carinii pneumonia. Our diagnosis was based on quantitative cultures of broncho-alveolar lavage fluid (9 cases, two of them with concurrent positive blood cultures/positive cultures of the pleural fluid), pleural puncture (one case), sputum in pneumonias responding only to antipseudomonas therapy (3 cases), and autopsy (2 cases). 8 patients died of pseudomonas pneumonia within 1-3 months despite therapy. 7 patients received pseudomonas-specific combination therapy, but all died after median 9 (4-15) months of the underlying illness. In 3 cases recurrent pseudomonas pneumonia could be documented bacteriologically. We conclude that in HIV-infected patients pneumonia caused by P. aeruginosa is a significant and severe pulmonary complication.

AIDS-Related Opportunistic Infections↗

PubMed1999

Oxygen and placental vascular development.

Human embryogenesis takes place in a hypoxic environment because the trophoblast shell excludes entry of maternal blood. The first fetal-placental villi develop as trophoblast sprouts. These are invaded by allantoic mesoderm to form secondary villi and are transformed, by vasculogenesis, into tertiary villi. The placental barrier to maternal blood is gradually breached between 8-12 weeks of gestation, due to invasion of placental-bed uteroplacental spiral arteries by the extravillous trophoblast (EVT). Placental oxygen tension thus rises and a phase of branching angiogenesis continues until 24 weeks. Thereafter a gradual shift takes place favoring non-branching angiogenesis. Gas-exchanging terminal villi thus form which are essential for rapid fetal growth and development of a high-flow, low-resistance fetal-placental circulation. Inadequate invasion of the uteroplacental spiral arteries by EVT results in placental ischemia and the development of obstetrical complications--preeclampsia and/or intrauterine growth restriction (IUGR). Placental villi often show evidence of continued branching angiogenesis, as is the case with anemic pregnancy, and pregnancy at high altitude. These structural alterations may reflect continued hypoxia-driven activity of vascular endothelial growth factor (VEGF). By contrast, a minority of severe early-onset IUGR pregnancies exhibit reduced fetal-placental blood flow with elongated maldeveloped villous capillaries. Placenta-like growth factor (PIGF) expression is increased while trophoblast proliferation is reduced, suggesting "hyperoxia" in the placental villous tree. IUGR may thus have two phenotypes--a more common hypoxic and a rarer hyperoxic type. While this concept is gaining acceptance, we have no insight as to the initiating mechanism(s).

Animals↗

PubMed1999

Q.E.D. Alcohol test: a simple and quick method to detect ethanol in saliva of patients in emergency departments. Comparison with the conventional determination in blood.

OBJECTIVE: The aim of this pilot study was to assess whether ethanol concentrations in saliva are comparable to those in blood and to evaluate whether this new non-invasive saliva alcohol test is suitable for use in emergency departments. DESIGN: Prospective, open, non-randomised study. SETTING: University hospital emergency department. PATIENTS AND METHODS: 100 consecutive patients who were admitted to the emergency department whose smell and/or behaviour indicated alcohol abuse. Fifteen patients participated as a control group after they were asked to abstain from alcohol consumption for 24 h before the study. INTERVENTIONS: Blood and saliva samples were obtained at the same time for ethanol measurement. The Q.E.D. Alcohol Test A350 was used in order to measure the concentration of ethanol in saliva. Blood samples were analysed by the alcohol dehydrogenase method. RESULTS: The mean difference between the ethanol levels in blood and saliva was -0.1 mg/dl, whereas the values measured in saliva were on average 0.1 mg/dl higher than those measured in blood (p = 0.002). CONCLUSION: The Q.E.D. Alcohol Test A 350, which uses saliva, is well suited for quantitative determination of alcohol levels. The levels measured in saliva correlate well with those measured in blood at both the lower and the upper end of the scale. Because this test is quick and easy to perform by emergency room personnel and the results are accurate enough for clinical purposes, it should prove valuable to determine whether impaired consciousness is related to alcohol intoxication or to other likely causes.

Adolescent↗

PubMed1999

The apoptosis cascade--morphological and immunohistochemical methods for its visualization.

Apoptosis is involved in morphogenesis of embryonic tissues as well as in homeostasis of adult organs and tissues. It is the main process by which organs maintain cell mass and at the same time eliminate excess and aged cells that have lost their functional importance. The typical morphological signs of apoptosis (cellular shrinkage, membrane blebbing, nuclear condensation and fragmentation) are the final results of a complex biochemical cascade of events, some of which are inextricably linked to the process of differentiation. Studies that analyze all stages of this cascade, rather than the final morphological stages of apoptotic death, are essential in order that specific link(s) between differentiation and apoptosis are appreciated. This review outlines the main stages of the apoptosis cascade together with current methods for their morphological visualization. Starting with (a) receptors and ligands known to induce apoptosis, we continue with (b) early initiator stages of apoptosis, and (c) proteins regulating and potentially inhibiting further progression of the cascade, into (d) irreversible execution stages of the cascade, and finally (d) the morphological events of apoptotic death. For each stage we present those aspects of the biochemical background that are morphologically relevant, together with proven methods for their visualization. We offer technical advice at each stage based upon our experience of studying differentiation and apoptosis in human placental trophoblast.

Animals↗

PubMed1999

Different placentation patterns in viable compared with nonviable tubal pregnancy suggest a divergent clinical management.

OBJECTIVE: In contrast to tubal abortions, viable ectopic pregnancies in color Doppler ultrasonography exhibit a signal-intensive ring around the gestational sac. We investigated the underlying differences in implantation and placentation. STUDY DESIGN: Histologic sections of fallopian tubes carrying viable tubal pregnancies (13 patients) and tubal pregnancies that aborted (8 patients) were immunostained for cytokeratin, MIB-1, CD-34, and CD-68. The data were studied by computer-aided image analysis followed by statistical evaluation (Student t test, P <.05). RESULTS: In contrast to tubal abortions, viable tubal pregnancies are characterized by implantation at the mesosalpingial rather than at the antimesosalpingial side of the organ. They exhibit deeper trophoblast invasion into the thickened tubal wall, more intense trophoblast proliferation (P <.001), and increased villous vascularization (P <.001). CONCLUSION: The morphologic findings correlate with preoperative Doppler ultrasonography. They suggest that trophoblast invasion, placental growth, and the fate of tubal pregnancies depend on the implantation site. They encourage a conservative management of anti-mesosalpingially implanted, nonviable ectopic pregnancies in clinically stable patients.

Antigens, CD↗

PubMed1999

Umbilical Doppler waveforms and placental villous angiogenesis in pregnancies complicated by fetal growth restriction.

OBJECTIVE: To test the hypothesis that the characteristics of umbilical artery Doppler flow velocity waveforms in growth-restricted fetuses indicate angiogenesis within placental stem and gas-exchanging villi. METHODS: We examined 18 placentas from singleton fetuses that were normal structurally and chromosomally but were growth-restricted, preterm, and complicated by preeclampsia. Ten cases with positive end-diastolic flow and eight with absent or reverse end-diastolic flow were compared with six gestational age-matched controls. Sections of villous placenta were examined to determine structural composition (percentage of fibrinoid, intervillous space, and villous tissue), relative proportion of villous types (stem, immature intermediate, and gas-exchanging villi), and the frequency distribution of stem arterial vessel calibers and their branching pattern. RESULTS: Placentas with positive end-diastolic flow had a significantly (P < .05) higher percentage of gas-exchanging villi (median 69.6%, range 62.5-80.8%) than those with absent or reverse end-diastolic flow (58.3%, 29.9-71.9%) or controls (60.8%, 43.1-65.6%). The gas-exchanging villi from placentas with absent or reverse end-diastolic flow were slender, elongated, poorly branched, and poorly capillarized. There was a progressive trend toward reduced branching of the stem arteries from the controls (median 22%, range 2-38%), through the positive end-diastolic group (17%, 11-20%), to the absent or reverse end-diastolic group (13%, 4-23%). CONCLUSION: Compared with absent or reverse end-diastolic flow, the placentas from growth-restricted fetuses with positive end-diastolic flow showed a normal pattern of stem artery development, accompanied by increased capillary angiogenesis and terminal villous development. These features suggest an adaptive pathway for the placenta in the face of uteroplacental ischemia.

Chorionic Villi↗

PubMed1999

Behavioral and pharmacologic interventions: the Raynaud's Treatment Study.

The Raynaud's Treatment Study (RTS) exemplified clinical trials with treatments that differ qualitatively both in their modes and in their methods of delivery. The RTS compared finger-temperature biofeedback to slow-release nifedipine, a calcium channel blocker, in patients with primary Raynaud's disease. Factors influencing the study design were the nature of the interventions and control measures of the protocol, the possibility of perceived differences by the patients between the treatments once the final protocol was developed, and concern on the part of the investigators over the fact that the primary endpoint was self-reported. This paper presents the final statistical model: a double parallel design with both a placebo group and a nonspecific behavioral control group.

Biofeedback, Psychology↗

PubMed1999

Connexin expression patterns in human trophoblast cells during placental development.

This study focuses on the gap junction expression pattern in trophoblast cells during human placental development in vivo and in vitro. Investigations of cell-cell communication properties within the subpopulations of trophoblast responsible for invasion, placental growth and feto-maternal transport seem of special interest because the intercellular channels are believed to coordinate proliferation and differentiation processes. From all gap junction connexins (Cx) investigated (Cx26, Cx31, Cx32, Cx37, Cx40, Cx43), Cx40 was the only connexin clearly detected within the cytotrophoblast of human placenta, and was restricted to the extravillous trophoblast of cell islands and cell columns. Most intense staining was found in the juxtastromal area correlated to the proliferating extravillous trophoblast cells. Connexin protein expression was missing during trophoblast migration into the decidua but was re-expressed in trophoblast aggregates within the decidua. Cx40 expression decreased with progressing pregnancy and no connexins could be detected in villous or extravillous trophoblast of mature placentae. In parallel, isolated trophoblast cells of first and second trimester placentae revealed Cx40 expression and, in contrast to the situation in vivo, Cx43 was also found. In isolated cells of mature placentae, expression of both Cx40 and Cx43 transcripts was decreased to low levels and Cx40 immunoreactivity was absent. Cx43 protein, however, was still detectable in trophoblast cultures of term placentae. Our studies suggest that Cx40 is the characteristic channel for the proliferating cell population of cell islands and cell columns of first and second trimester placentae and isolated trophoblast and is probably involved in regulation and coordination of the invasive pathway.

Cell Division↗