Licensing health professionals: quality, competitive health care

In licensing health professionals, states need to protect the public from unqualified practitioners without limiting price competition or consumer freedom. Attorneys general play a vital role in regulating professions and in protecting consumer interests in health care.

Nucleotide and deduced amino acid sequence of the hydrophobic surfactant protein SP-C from rat: expression in alveolar type II cells and homology with SP-C from other species

Pulmonary surfactant lowers surface tension in the lung. Its deficiency leads to the severe physiologic abnormalities seen in the respiratory distress syndrome. The hydrophobic surfactant proteins, SP-B and SP-C, appear to be especially important in the surface-spreading characteristics of pulmonary surfactant. We report the nucleotide sequence of cDNA clones for rat SP-C and compare the deduced amino acid sequence for SP-C from several species. A highly conserved domain exists within the confines of mature human SP-C. An Eisenberg plot of this region predicts a membrane-associated helix. We also demonstrate by Northern analysis the tissue-specific expression of SP-C. A comparison of signal strength between total lung RNA and RNA derived from isolated type II cells supports the idea that most SP-C messenger RNA in total lung can be accounted for by that present in alveolar type II cells.

cDNA and deduced amino acid sequence for the rat hydrophobic pulmonary surfactant-associated protein, SP-B

Pulmonary surfactant prevents collapse of lung alveoli by lowering surface tension at the air/liquid interface. The hydrophobic surfactant associated proteins SP-B and SP-C have been shown to be important in surfactant function and metabolism. A cDNA clone for rat SP-B was isolated and sequenced. Northern analysis showed mRNA for SP-B was present in whole lung and was greatly enriched in alveolar type II cells, but was not present in brain, kidney, spleen or liver. A full length transcript of the rat SP-B cDNA clone consists of 1536 bases and encodes an open reading frame of 376 amino acids. The predicted molecular mass of the primary translation product is 42 kDa and the predicted molecular mass of the mature protein is 8 kDa. Extensive homology exists between the rat sequence for SP-B and those reported for human and canine SP-B. The position of 25 cysteine residues has been extremely well preserved across all three species. An N-linked glycosylation site in the COOH region has been conserved across all three species. A search of the NIH database revealed homology between rat SP-B and the active site for the mouse contrapsin serum proteinase inhibitor.

Improved maintenance of adult rat alveolar type II cell differentiation in vitro: effect of hydrocortisone and cyclic AMP

We have examined the effect of hydrocortisone and cyclic AMP on the maintenance of lipid synthesis in primary cultures of adult rat alveolar type II cells. These hormones were tested in the presence of either 1% or 5% charcoal-stripped rat serum (CS-rat serum). The effect of substratum on responsiveness to these hormones was evaluated by comparing cells cultured for 4 days on tissue culture plastic, on floating type I collagen gels, on rat lung fibroblast feeder layers on floating collagen gels (floating feeder layers), and on Engelbreth-Holm-Swarm (EHS) tumor basement membrane gels. Type II cells cultured on floating feeder layers in medium containing 1% CS-rat serum and 10(-5) M hydrocortisone plus 0.5 mM dibutyryl cyclic AMP exhibited significantly increased incorporation of [14C]acetate into total lipids (238% of control). The hormone combination also increased the relative percentage of acetate incorporated into phosphatidylglycerol (PG; 7.3% versus 1.9%) and saturated phosphatidylcholine (PC; 43.6% versus 37.6%). The percentage of acetate incorporated into neutral lipids was significantly decreased by the addition of hormones (28.6% versus 70.0%). The addition of hydrocortisone and cyclic AMP to medium containing 5% CS-rat serum resulted in an increase in the relative incorporation of acetate into saturated PC (51.2% versus 46.4%), but had no effect on the relative incorporation of acetate into PG or on the incorporation of acetate into total lipids. Type II cells cultured on EHS gels in medium containing 1% CS-rat serum plus hydrocortisone and cyclic AMP showed increased acetate incorporation into total lipids (204% of control) and a relative decrease in the percentage of acetate incorporated into neutral lipids (16.9% versus 47.0%). The hormone combination also increased the relative incorporation of acetate into PG (4.4% versus 2.5%) and saturated PC (49.9% versus 42.1%). Hydrocortisone and cyclic AMP added to medium containing 5% CS-rat serum concentration increased the relative incorporation of acetate into saturated PC by type II cells on EHS gels, but these additions had no effect on acetate incorporation into PG. No responses to these soluble factors were seen when type II cells were cultured on floating type I collagen gels without feeder layers or on tissue culture plastic. These data indicate that there are positive interactions between substratum, soluble factors and serum in the maintenance of differentiated function of adult rat alveolar type II cells in vitro.

Alkaline phosphatase: a marker of alveolar type II cell differentiation

In an effort to identify type II cells by a method independent of staining phospholipid inclusions, we evaluated a histochemical technique for alkaline phosphatase activity in normal rat lung, in freshly isolated type II cells, and in primary culture of type II cells. In the adult rat alveolus, alkaline phosphatase staining selectively identified type II cells, although nonciliated bronchiolar (Clara) cells and loose perivascular connective tissue also stained for alkaline phosphatase activity. In cell suspensions of type II cells and other dissociated lung cells, alkaline phosphatase staining correlated closely with the modified Papanicolaou technique and was particularly useful in distinguishing type II cells from alveolar macrophages. To determine if alkaline phosphatase was related to the differentiated phenotype of type II cells, we studied conditions known to affect other type II cell functions. When type II cells were cultured on plastic substrata, the intensity of alkaline phosphatase staining decreased with increasing time in culture. To quantitate the apparent decrease in alkaline phosphatase activity, we used a biochemical assay to study the expression of alkaline phosphatase by type II cells. The specific activity of alkaline phosphatase in type II cells declined with increasing time in tissue culture on plastic substrata. Alkaline phosphatase activity was maintained, however, by culturing cells on Englebreth-Holm-Swarm (EHS) tumor matrix. Cells that had reduced levels of alkaline phosphatase activity following 48 h of culture on plastic substrata could be "rescued" by removing them from the plastic substratum and reculturing them for 48 h on EHS matrix. Alkaline phosphatase activity was also increased by culturing type II cells in the presence of cAMP or sodium butyrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional differentiation of alveolar type II epithelial cells in vitro: effects of cell shape, cell-matrix interactions and cell-cell interactions

Alveolar type II epithelial cells rapidly lose characteristics of differentiated function when cultured on plastic dishes. We have attempted to circumvent this problem by culturing type II cells under conditions that might better reproduce their environment in vivo. Cell-matrix interactions were studied by culturing isolated adult rat type II cells on Engelbreth-Holm-Swarm (EHS) tumor basement membrane. Aggregates of type II cells formed on the surface of the matrix during 4 days in culture. Microscopic examination of these aggregates revealed cuboidal cells that retained more characteristics of differentiated type II cells than did cells cultured on plastic. Type II cells cultured on EHS matrix incorporated a higher percentage of acetate into phosphatidylcholine (PC) than did cells on plastic, and a higher percentage of this PC was saturated. Phosphatidylglycerol (PG) synthesis by these cells was no different from that seen in cells on plastic. The effects of cell-cell interactions and cell shape were evaluated by culturing type II cells on feeder layers that in turn were grown on collagen gels. The feeder layer cells included fetal rat lung fibroblasts, adult rat lung fibroblasts, fetal rat skin fibroblasts, bovine aortic endothelial cells, and rat mammary tumor epithelial cells. One-half of the gels remained attached to the culture dish and one-half of the gels were detached after 24 h and allowed to float free in the medium. Type II cells grown in association with any of the attached feeder layers became flattened and lost their differentiated phenotype. These cells incorporated no greater percentage of acetate into PC than did cells on plastic. Saturated PC synthesis was modestly increased. PG synthesis declined in parallel with that seen in cells cultured on plastic. Type II cells cultured on feeder layers that were detached assumed their native cuboidal shape and also exhibited many morphological characteristics of differentiated function. These cells incorporated a significantly greater percentage of acetate into PC compared to cells on either plastic or attached feeder layers. Saturated PC synthesis also increased markedly. These cells, however, incorporated no greater percentage of acetate into PG than did cells on plastic or attached feeder layers. These data suggest an important role for cell shape and cell-matrix interactions and maintenance of type II cell differentiation. The effects of cell-cell interactions, while beneficial, appear to be non-specific.

Androgen-induced biochemical responses in epithelium lacking androgen receptors: characterization of androgen receptors in the mesenchymal derivative of urogenital sinus

Heterotypic tissue recombinants, composed of adult bladder epithelium obtained from testicular feminization syndrome mice (TfmBLE) and embryonic wild-type rat urogenital sinus mesenchyme (UGM) were grown as subcapsular renal grafts in male athymic nude mice for 30 days. The resultant prostatic tissue that developed was subjected to extensive biochemical analyses for androgen receptors. From previous autoradiographic studies it was shown that UGM possesses androgen receptors and induces the TfmBLE to form prostatic ductal-acinar epithelium that lacks androgen receptors. The purpose of the present study is to biochemically characterize the mesenchymal androgen receptors. According to results obtained by autoradiographic analyses, androgen receptors are expressed in the mesenchyme of tissue recombinants. Cytosolic androgen receptors analyzed by the Scatchard method utilizing R-1881 as a ligand showed that the dissociation constant (Kd) of androgen receptors localized within the mesenchyme of the tissue recombinants differs from that found in the mouse prostate gland, but resembles that found in the rat ventral prostate (VP). Sucrose density gradient analysis of the cytosol androgen receptors showed the presence of 8 S [3H]dihydrotestosterone (DHT) binding component under the low salt condition. The mesenchymal androgen receptors are capable of translocating efficiently from cytosol to nuclear compartment, seemingly unaffected by adjacent TfmBLE. The quantity of both cytosol and nuclear androgen receptors expressed in tissue recombinants is only about 1/3 of that found in the rat VP and is in agreement with the morphometric analysis of tissue recombinants, which indicated that about 1/3 of the cells in the tissue recombinants are stromal cells. These results extend previous autoradiographic results and further suggest that androgen receptors present in the mesenchymal compartment may be necessary for the expression of androgen-elicited responses in the TfmBLE that lacks androgen receptors. In addition, this study confirms a novel model system for the study of mesenchymal androgen receptors in tissues unmolested by mechanical or enzymatic dissociation.

Characterization of androgen binding and deoxyribonucleic acid synthesis in prostate-like structures induced in the urothelium of testicular feminized (Tfm/Y) mice

We have examined tissue recombinants composed of wild-type (rat or mouse) urogenital sinus mesenchyme plus adult testicular feminized (Tfm/y) bladder epithelium for the autoradiographic localization of androgen binding. In the presence of androgens, wild-type mesenchyme reprogrammed the androgen-insensitive bladder epithelium to undergo prostatic morphogenesis. Steroid autoradiography of [3H] dihydrotestosterone or [3H] methyltrienolone binding in these recombinants, however, showed that the ligands were specifically bound only in the nuclei of stromal cells, indicating that the effects of androgens on prostatic morphogenesis are mediated by the mesenchyme. Furthermore, autoradiograms prepared from recombinants that were exposed to [3H] thymidine showed that the generation of prostatic form required a specific, androgen-induced proliferation in the androgen-insensitive bladder epithelium. The significance of these data in relation to epithelial-stromal interactions occurring during prostate development is discussed.

Lack of nuclear estrogen binding in benign mesothelioma of the uterus

Estrogen binding sites in a benign mesothelioma of the uterus was studied by in vitro steroid autoradiography. Unlike normal myometrium, which shows distinct supanuclear localizations of tritiated estradiol, the cellular components of the benign mesothelioma do not appear to have estrogen receptors. Serial sections through the tumor failed to localize sites of estrogen binding. These findings are congruent with an undifferentiated mesothelial organ for the tumor and suggest a lack of response to endogenous sex steroids.

Transplanted mammary epithelium grows in association with host stroma: aging of serially transplanted mammary gland is intrinsic to epithelial cells

Mouse mammary gland displays an irreversible decline in growth rate when propagated by serial transplantation in gland-free mammary fat pads of isogeneic mice. Because transplanted fragments of gland contain both mammary epithelial and stromal elements, the present study was undertaken to distinguish between two possibilities: (1) stromal cells in the implants proliferate in coordination with epithelium as the mammary ductal tree regenerates at each passage, or (2) transplanted epithelial tissue interacts exclusively with host stroma. Mammary xenografts from 18-week-old virgin Sprague-Dawley rats were implanted into gland-free mammary fat pads of athymic Balb/cNu/Nu mice. These rat xenografts regenerated chimeric mammary ductal outgrowths. When sectioned and stained with Hoechst dye 33258, a procedure that provides for unambiguous identification of mouse cell nuclei, rat mammary epithelium was found to be associated with mouse stromal cells; only at the site of transplantation were occasional rat stromal nuclei observed. This indicates that as mouse epithelial tissue becomes progressively aged during serial transfer in young mice, the stromal components are refreshed during each passage. The primary lesion underlying the mammary aging phenomenon must therefore be intrinsic to the epithelial cells.

The autoradiographic demonstration of estrogen binding in normal human cervix and vagina during the menstrual cycle, pregnancy, and the menopause

Using the technique of in vitro steroid autoradiography, the localization and modulation of nuclear estrogen binding sites has been studied in normal human cervix and vagina during the menstrual cycle, pregnancy, and the menopause. Marked differences occur in nuclear estrogen binding between these two organs. Nuclear estrogen binding varies throughout the menstrual cycle in the vaginal epithelium, whereas vaginal stromal cells consistently exhibit nuclear estrogen binding throughout the cycle. In contrast, the cervical squamous and columnar epithelia show much less cyclic variability in nuclear estrogen binding sites. As in the vagina, the cervical stroma consistently binds estrogen. High levels of nuclear estrogen binding sites are found in the vagina of the postmenopausal patient, and lower levels of binding occur postpartum. The implications of these localizations, with special reference to the role of the cervical and vaginal stroma, are discussed.

Autoradiographic demonstration of high affinity nuclear binding and finite binding capacity of [3H]estradiol in mouse vaginal cells

Vaginae from adult C57Bl/6J mice were analyzed for nuclear estrogen-binding sites by biochemical as well as in vitro steroid autoradiographic methods. Finite binding capacity (saturability) and high affinity binding were demonstrated in stromal cell nuclei (Kd = 1.0 nM) by autoradiographic methods and in nuclear extracts of vaginal homogenates (Kd = 1.9 nM) by biochemical techniques. The results of this study demonstrate that all criteria considered definitive for estrogen receptors can be met by autoradiographic analysis, which makes feasible the assessment of estrogen receptor activity in the individual cell types that comprise fetal and neonatal estrogen target organs.

Epithelial-mesenchymal interactions in prostatic development. I. morphological observations of prostatic induction by urogenital sinus mesenchyme in epithelium of the adult rodent urinary bladder

Tissue recombinants of embryonic urogenital sinus mesenchyme (UGM) and epithelium of the urinary bladder (urothelium, BLE) of adult rats and mice were grown for 3-30 d in male syngeneic hosts. Short-term in vivo growth indicated that prostatic morphogenesis is initiated as focal outgrowths from the basal aspect of the adult urothelium. The solid epithelial buds elongate, branch, and subsequently canalize, forming prostatic acini. After 30 d of growth in the male hosts, prostatic acini exhibit secretory activity. The marked changes in urothelial morphology induced by the UGM are accompanied by the expression of fine-structural features indicative of secretory function (rough endoplasmic reticulum, Golgi apparatus, and secretory granules). During this process, urothelial cells express prostatic histochemical markers (alkaline phosphatase, nonspecific esterase, glycosaminoglycans) and prostate-specific antigens. The expression within BLE of prostatic characteristics is associated with the loss of urothelial characteristics. These data indicate that adult urothelial cells retain a responsiveness to embryonic mesenchymal inductors. Furthermore, mesenchyme-induced changes in urothelial cytodifferentiation appear to be coupled to changes in functional activity.

Nuclear estrogen binding sites in human endometriosis

With a technique of in vitro steroid autoradiography, the localization of nuclear estrogen binding sites has been studied in ovarian endometriotic foci from untreated patients in both the follicular and luteal phases of the cycle. Unlike the uterine endometrium, which displays cyclic changes in estrogen binding sites, the endometriotic foci show no such changes in the localization of estrogen binding sites. Throughout the cycle, a marked degree of estrogen binding is present in the stromal cells of the endometriotic foci, while in the uterine endometrium stromal binding sites are seen only during the proliferative phase and not during the secretory phase of the cycle. The glandular epithelium of the endometriotic foci displays a patchy localization of nuclear estrogen binding sites at all stages, while the glandular epithelium of the uterus is strongly positive during the proliferative phase but displays no estrogen binding sites during the secretory phase of the cycle. Thus, the endometriotic foci appear to respond differently to ovarian hormones, both in terms of the modulation of estrogen binding and in terms of glandular histology.

Autoradiographic localization of androgen binding in the developing mouse prostate

The ontogeny of expression of [3H]dihydrotestosterone (3H-DHT) binding in the developing mouse prostate was studied using steroid autoradiography. At all prenatal stages examined, 3H-DHT binding in the urogenital sinus was restricted to the stromal tissue compartment. This pattern of binding continued until approximately day 4 of postnatal life, when some epithelial cells began to exhibit nuclear localization of 3H-DHT. The pattern of binding was asynchronous within the prostate, with the onset of nuclear labeling seemingly correlated with canalization of prostatic ducts. By 3 weeks of age, virtually all prostatic epithelial cells exhibited nuclear labeling with 3H-DHT. The significance of these results, with respect to the role of epithelial-mesenchymal interactions in hormone-induced development, are discussed.

Autoradiographic localization of steroid binding in human tissue labeled in vitro

A procedure for the rapid preparation of autoradiograms from tissues incubated in vitro with 3H-estradiol is described. Slices of tissue were incubated in culture medium containing 17 nM 3H-estradiol, washed to remove unbound steroid, then processed for thaw-mount autoradiography. Exposure times were generally 3 to 4 weeks. Simultaneous in vitro competition with unlabeled progesterone, dihydrotestosterone, or hydrocortisone had no effect on the distribution or intensity of exposed silver grains, while competition with unlabeled estradiol or moxestrol abolished nuclear localization of silver grains. The exchange of labeled estradiol for bound endogenous estradiol during in vitro incubation of the tissues was demonstrated by a comparison of the pattern of incorporation of 3H-estradiol in tissues previously treated in vivo with unlabeled estradiol versus those not primed. A similar distribution and intensity of silver grains was observed in both the treated and untreated tissue groups. The rationale for the advantages of in vitro steroid autoradiography versus the in vivo technique is discussed.

Autoradiographic analysis of nuclear estrogen binding sites during postnatal development of the genital tract of female mice

Autoradiographic analysis of [3H]-estrogen nuclear binding sites was performed on developing genital tracts (uterus, cervix and vagina) of mice 1 to 90 days postpartum. During days 1 to 15 postpartum, nuclear estrogen binding sites were observed exclusively within mesenchymal cells; epithelial cells did not exhibit nuclear labelling. At 18 days postpartum vaginal and cervical epithelial cells exhibited nuclear estrogen binding sites for the first time, whereas the initial appearance of estrogen receptor activity in the epithelium of the uterus was detected at 20 days postpartum. Thereafter, nuclear estrogen binding sites were maintained in both epithelial and stromal cells into adulthood. The acquisition of nuclear binding sites within epithelium of female genital organs at 18 days is discussed in terms of epithelial-mesenchymal interactions and the acquisition of growth responsiveness.

The influence of cell shape on the induction of functional differentiation in mouse mammary cells in vitro

To define more clearly the in vitro conditions permissive for hormonal induction of functional differentiation, we cultured dissociated normal mammary cells from prelactating mice in or on a variety of substrates. Cultivation of an enriched epithelial cell population in association with living adult mammary stroma in the presence of lactogenic hormones resulted in both morphological and biochemical differentiation. This differentiation, however, was not enhanced over that seen when the cells were associated with killed stroma, provided that the killed stroma had a flexibility similar to that of the living stroma. Cells cultured in inflexible killed stroma usually did not differentiate. Cells cultured within the flexible environment of a collagen gel, but removed from the gas-medium interface, differentiated in a manner similar to those cultured in flexible stroma. Cells cultured on the surface of an attached collagen gel were squamous, and their basolateral surfaces were sequestered from the medium; they did not differentiate. Cells cultured on floating collagen gels were cuboidal-columnar, with basolateral surfaces exposed to the medium, and showed good functional differentiation. Cells cultured on inflexible floating collagen gels were extremely flattened and had exposed basolateral surfaces, and showed no evidence of functional differentiation. We infer that assumption of cuboidal to columnar shapes differentiation in vitro. The additional requirement of basolateral cell surface exposure also is important.

Mesenchymal-epithelial interactions in sex differentiation

Development of male and female accessory sexual glands is described in terms of the respective roles of epithelium and mesenchyme. During embryonic and neonatal periods mesenchyme alone exhibits androgen receptor activity (nuclear androgen binding sites) and is the actual target and mediator of the morphogenetic effects of androgens upon the epithelium. Mesenchyme induces specific patterns of epithelial morphogenesis, cytodifferentiation, and probably also specifies the functional (biochemical) activities of the epithelium. Mesenchymal influence upon expression of epithelial characteristics occurs in the perinatal period during morphogenesis, but also plays an important role in adulthood by maintaining favorable conditions for maintenance of epithelial morphology and function. Morphogenetic processes in adult hormone-dependent organs are though to be mediated by stromal cells.

Treatment os severe atrial injuries

Four cases of severe atrial trauma are presented. These cases are unusual because of the magnitude of injury and because of their presentation in hospitals not usually involved in cardiac surgery. Three of the patients had blunt atrial injury. We found only 21 other successfully treated blunt atrial tears in our search of the world's literature. In patients with blunt atrial injuries, the setting of a high speed vehicle accident, significant chest trauma, hypotension, mental confusion and increased venous pressure should alert the emergency physician to the possibility of cardiac rupture. The use of simple operative techniques and the knowledge that most cardiac ruptures repaired successfully involve the atrium may help the surgeon produce a successful outcome.

Long-term organ culture of mouse mammary gland

A method for maintaining mouse mammary gland in organ culture for periods of at least 30 days is described. Strips of the number four mammary glands were cultured in individual tubes while fully submerged in Medium 199 supplemented with insulin, aldosterone, ovine prolactin and bovine growth hormone. Exchange processes were aided by slowly rotating the tubes during culture. Mammary tissue from midpregnant BALB/c and virgin GR/A mice was induced to undergo lobulo-alveolar development, secrete and remain differentiated and metabolically active for the period of culture. Cells of both the ductal and alveolar epithelium continued to synthesize DNA and divide. The submerged roller-tube culture allows the use of larger pieces of tissue than can be accommodated in static culture, and the technique may prove applicable to culture of a variety of tissues.

Factors Involved in Recovery from Experimental Skeletal Muscle Ischemia Produced in Dogs: I. Histologic and Histochemical Pattern of Ischemic Muscle

Images