If the gut works use it

Using education and increased monitoring, a nutritional support team lowered parenteral nutrition days from 84 to 5 per quarter, increased the proportion of patients meeting their nutritional requirements from 75% to 97%, and saved money.

Nonallelism for the audiogenic seizure prone (Asp1) and the aryl hydrocarbon receptor (Ahr) loci in mice

Previous studies showed an association between the Ahr locus on Chr 12 and a major gene, Asp1, that influences susceptibility to audiogenic seizures (AGS) in mice. Although the association was thought to involve close linkage, a pleiotropic effect of the Ahr locus on AGS susceptibility was not excluded. Two congenic strains, D2.B6N-Asp1b and the D2N.B6N-Ahrb1, were used to evaluate further the association between the Ahr and Asp1 loci. Both strains are genetically identical to the AGS susceptible DBA/2 (D2) strain except for a small amount of C57BL/6N (B6N) genome surrounding the Ahr locus and encompassing the Asp1 locus. The AGS susceptibility of both congenic strains is similar and significantly lower than that of the D2 strain. We found that the Ahr/Asp1 critical region encompasses 5.5-7.0 cM from the proximal microsatellite marker D12Mit153 to the distal marker D12Mitl12. The D2N.B6N-Ahrb1 expresses B6 alleles for all markers within the critical region, whereas the D2.B6N-Asp1b expresses the B6 allele only at the Asp1 locus. Furthermore, we determined that the D2.B6N-Asp1b mouse expresses both the D2 phenotype and genotype at the Ahr locus, i.e., zoxazolamine paralysis and T to C and G to A transition mutations in the Ahr cDNA at bp sites 3330 and 3336, respectively. We therefore conclude that the Ahr and Asp1 loci are nonallelic and that the Ahr gene is excluded as a candidate for Asp1.

The DNA binding activity of metal response element-binding transcription factor-1 is activated in vivo and in vitro by zinc, but not by other transition metals

We examined the DNA binding activity of mouse and human MTF-1 in whole cell extracts from cells cultured in medium containing zinc or cadmium and from untreated cells after the in vitro addition of zinc or cadmium, as well as using recombinant MTF-1 transcribed and translated in vitro and treated with various transition metals. Incubation of human (HeLa) or mouse (Hepa) cells in medium containing cadmium (5-15 microM) did not lead to a significant increase (<2-fold) in the amount of MTF-1 DNA binding activity, whereas zinc (100 microM) led to a 6-15-fold increase within 1 h. MTF-1 binding activity was low, but detectable, in control whole cell extracts and was increased (>10-fold) after the in vitro addition of zinc (30 microM) and incubation at 37 degrees C for 15 min. In contrast, addition of cadmium (6 or 60 microM) did not activate MTF-1 binding activity. Recombinant mouse and human MTF-1 were also dependent on exogenous zinc for DNA binding activity. Cadmium did not facilitate activation of recombinant MTF-1, but instead inhibited the activation of the recombinant protein by zinc. Interestingly, glutathione (1 mM) protected recombinant MTF-1 from inactivation by cadmium, and allowed for activation by zinc. It was also noted that zinc-activated recombinant MTF-1 was protected from cadmium only when bound to DNA. These results suggest that cadmium interacts with the zinc fingers of MTF-1 and forms an inactive complex. Of the several transition metals (zinc, cadmium, nickel, silver, copper, and cobalt) examined, only zinc facilitated activation of the DNA binding activity of recombinant MTF-1. These data suggest that transition metals, other than zinc, that activate MT gene expression may do so by mechanisms independent of an increase in the DNA binding activity of MTF-1.

Uroporphyria produced in mice by iron and 5-aminolaevulinic acid does not occur in Cyp1a2(-/-) null mutant mice

In the present study we have investigated the putative requirement for the cytochrome P-450 isoform CYP1A2 in murine uroporphyria, by comparing Cyp1a2(-/-) knockout mice with Cyp1a2(+/+) wild-type mice. Uroporphyria was produced by injecting animals with iron-dextran and giving the porphyrin precursor 5-aminolaevulinic acid in the drinking water. Some animals also received 3-methylcholanthrene (MC) to induce hepatic CYP1A2. In both protocols, uroporphyria was elicited by these treatments in the Cyp1a2(+/+) wild-type mice, but not in the null mutant mice. Uroporphyrinogen oxidation activity in hepatic microsomes from untreated Cyp1a2(+/+) mice was 2.5-fold higher than in Cyp1a2(-/-) mice. Treatment with MC increased hepatic CYP1A1 in both mouse lines and hepatic CYP1A2 only in the Cyp1a2(+/+) line, as determined by Western immunoblotting. MC increased hepatic ethoxy- and methoxy-resorufin O-dealkylase activities in both mouse lines, but increased uroporphyrinogen oxidation activity in the Cyp1a2(+/+) wild-type mice only. These results indicate the absolute requirement for hepatic CYP1A2 in causing experimental uroporphyria under the conditions used.

Activation of the chicken metallothionein promoter by metals and oxidative stress in cultured cells and transgenic mice

Cis-acting elements in the chicken metallothionein promoter were tested for their ability to direct responses of reporter genes to metal ions and oxidative stress in transfected mouse cells and in transgenic mice. In addition, protein interactions with the promoter were analyzed by the electrophoretic mobility shift assay. In transient transfection assays and in transgenic mice, 107-bp of the chicken MT promoter was sufficient to direct responses to Zn. This promoter region also directed response to oxidative stress in transfected cells and transgenic mice, but in transgenic mice, maximal responsiveness to oxidative stress apparently involved other elements in the proximal promoter region (307-bp). The proximal 200-bp of the promoter contains sequences homologous to a metal response element (-47-bp), Sp1 binding sites (-70-bp and -161-bp), and an antioxidant response element (-189-bp). Electrophoretic mobility shift assay demonstrated that metal response element binding activity was low in control Hepa cell nuclear extracts, but was induced 6-fold after 45 min of H2O2 treatment. In contrast, Sp1 binding remained unchanged, and no evidence for specific binding to the core antioxidant response element consensus sequence was obtained. These studies demonstrate that cis-acting elements mediating induction of metallothionein gene expression by metals and oxidative stress are present in the chicken metallothionein promoter and suggest a role for increased binding of the transcription factor MTF-1 to the metal response element(s).

Transgenic mice that overexpress metallothionein-I resist dietary zinc deficiency

Transgenic mice that overexpress metallothionein-I (MT-I) accumulate mo re MT-I and zinc in major organs than do control mice. The effects of overexpression of MT-I on resistance to dietary zinc deficiency were examined by feeding transgenic and control mice a zinc-deficient (0.5-1.5 micron/gram) or a zinc adequate (50 micron/g) diet and by measuring effects on pregnancy. When pregnant mice were maintained under conditions of dietary zinc deficiency, the number of resorptions and teratogenic defects of fetuses was greatly reduced in transgenic compared with control mice. Differences between transgenic and controls were not apparent at d 8 of pregnancy (d 1 = vaginal plug) but were apparent by d 14. This result suggests that the larger maternal zinc pool in the transgenic females allows fetal development to progress normally for a longer period of time. However, neither transgenic nor control zinc-deficient mice could complete pregnancy. Pancreatic MT concentrations were the greatest in zinc adequate transgenic mice. Moreover, there was >10-fold more MT per gram wet weight in the pancreas of transgenic mice than in any other organ examined. Pancreatic MT concentrations were an exceptionally sensitive indicator of zinc deficiency. Pancreatic MT declined 99.8% and zinc declined to basal levels by d 14 of pregnancy when transgenic and control mice were fed a zinc-deficient diet, whereas MT concentrations in other organs decreased only modestly. We suggest that the larger pool of zinc MT in the transgenic mice provides a biologically important labile pool of zinc during periods of zinc deficiency.

Transgenic mouse blastocysts that overexpress metallothionein-I resist cadmium toxicity in vitro

The role of metallothionein with regard to cadmium toxicity in vitro was investigated using preimplantation mouse blastocysts derived from a transgenic strain that constitutively overexpresses metallothionein-I transgenes (MT-I*). Northern blot and in situ hybridization revealed high levels of MT-I mRNA in transgenic blastocysts when compared with control blastocysts, and reverse transcriptase-polymerase chain reaction-amplified MT-I mRNA was almost exclusively MT-I*. Moreover, pulse-labeling experiments showed that the relative rate of synthesis of MT was 9-fold higher in transgenic blastocysts. Cadmium (Cd2+) toxicity was assessed after incubating blastocysts for 4 hr in Whitten's medium containing 50 microM Cd2+. Embryos that displayed abnormal morphology were judged "sensitive". Transgenic blastocysts were more resistant to cadmium-induced morphological changes than were control blastocysts. "Sensitive" and "resistant" blastocysts were individually genotyped by polymerase chain reaction, or they were transferred to foster mothers, and embryonic development to midterm was monitored. Of the blastocysts derived from mating heterozygous transgenic males with control females, 56% were transgenic before incubation with Cd2+, whereas 95% of the blastocysts that retained normal morphology after incubation were transgenic. Moreover, after Cd2+ exposure, transgenic blastocysts with normal morphology were nine times more likely to develop to midterm than were control blastocysts with normal morphology. Blastocysts with abnormal morphology failed to develop to midterm. These studies indicate that MT plays a central role in protection from Cd2+ toxicity within the physiological context of the developing mouse embryo.

Analysis of the effects of overexpression of metallothionein-I in transgenic mice on the reproductive toxicology of cadmium

Exposure to low levels of cadmium reduces fertility. In male mice spermatogenesis is highly sensitive to cadmium, whereas in females the peri-implantation period of pregnancy is sensitive. To examine the potential roles of the cadmium-binding protein, metallothionein (MT), in the reproductive toxicology of cadmium, we examined a transgenic mouse strain that overexpresses metallothionein-I (MT-I). These mice had dramatically increased steady-state levels of MT-I mRNA and MT in the testes and in the female reproductive tract during the peri-implantation period of pregnancy, and this overexpression occurred in a cell-specific and temporally regulated manner similar to that of the endogenous MT-I gene. Transgenic and control males were injected with cadmium, and the histology of the testes was examined. An injection of 7.5 mumol Cd/kg had no effect on histology of the testes in either transgenic or control mice. In contrast, an injection of 10 mumol Cd/kg caused rapid changes in the histology of the testes and resulted in pronounced testicular necrosis in both control and transgenic mice. Female transgenic and control mice were mated and then injected with cadmium (30-45 mumol Cd/kg) on the day of blastocyst implantation (day 4). In both of these groups, injection of cadmium reduced pregnancy rate, and no dramatic protection was afforded by maternal and/or embryonic overexpression of MT. Thus, overexpression of MT-I does not significantly protect against either of these cadmium-induced effects on fertility.

Activation of the complete mouse metallothionein gene locus in the maternal deciduum

The mouse metallothionein (MT) gene family consists of four known members (MT-I through IV) clustered on chromosome 8. Studies reported herein examine the expression and regulation of the MT-III and MT-IV genes in specific cell types in the maternal reproductive tract, developing embryo, and fetus known to express the MT-I and -II genes. MT-III and MT-IV mRNAs were absent from the visceral yolk sac, placenta, and fetal liver, tissues with high levels of MT-I and MT-II mRNAs. In contrast, MT-III and MT-IV mRNAs were both abundant in the maternal deciduum, and in experimentally induced deciduoma on 7 and 8 days postcoitum (1 dpc = vaginal plug), as are MT-I and -II mRNAs. The abundance of each of these MT mRNAs increased coordinately during development of the deciduum (6-8 dpc), and in situ hybridization localized MT-I, MT-III, and MT-IV mRNAs to the secondary decidual zone of the antimesometrial region on 8 dpc, where in some regions all of the cells were apparently positive. Thus, all of the known mouse MT genes are co-expressed in at least some of the cells in the secondary decidual zone. Electrophoretic analysis of decidual MT suggested that the MT-I, -II, and -III isoforms are abundant proteins in the secondary deciduum. Bacterial endotoxin-lipopolysaccharide (LPS) and Zn are powerful inducers of MT-I and MT-II gene expression in many adult organs, whereas these agents apparently have little effect on MT-III and MT-IV gene expression. Neither of these agents significantly effected levels of decidual MT-III or MT-IV mRNAs in vivo or in primary cultures of decidual cells in vitro, and only modest effects of Zn on MT-I mRNA levels were noted. During 2 days of in vitro culture, decidual cell MT-I and MT-III mRNA levels remained elevated while MT-IV mRNA levels decreased. Thus, expression of the mouse MT gene locus in the deciduum appears to be developmentally regulated, and in this tissue, the MT genes are refractory to induction by Zn or inflammation.

Characterization of metallothionein-I-transgenic mice

A metallothionein-I-transgenic mouse strain (MT-TG) was characterized to determine whether they would be suitable to study the functions of this protein. MT-TG mice were visually indistinguishable from nontransgenic littermate controls, but had 10- to 20-fold higher basal levels of MT protein in pancreas, liver, and stomach, as well as 2- to 6-fold higher MT protein levels in other organs (kidney, intestine, uterus, testes, spleen, heart, and lung) than control mice, as determined by the Cd/hemoglobin assay. The MT-TG mice had 50% more Zn in liver and 300% more Zn in pancreas than control mice. Interestingly, female MT-TG mice have 4- to 5-fold higher MT levels in liver than those of males. To determine whether MT can be further increased by well-known MT inducers, control and MT-TG mice were given Zn (200 mumol/kg), Cd (20 mumol/kg), or diethyl maleate (DEM, 5 mmol/kg), and tissue MT concentrations were measured 24 hr later. MT-TG mice responded to MT inducers in a manner similar to control mice. The hepatic antioxidant components (glutathione (GSH), GSH-peroxidase, GSH-reductase, GSH S-transferase, superoxide dismutase, DT-diaphorase, and catalase) of MT-TG mice were not different from those of controls. The cytochrome P450 enzymes (total P450, b5, NADPH cytochrome c reductase) were normal in these MT-TG mice. The activities of CYP1A, CYP2B, and CYP2E enzymes in MT-TG mice were also similar to those of controls, as determined by ethoxy- and pentoxyresorufin O-dealkylation and chlorzoxazone 6-hydroxylation. Thus, MT-TG mice appear to be a good model for studying functions of MT.

Temporalspatial patterns of expression of metallothionein-I and -III and other stress related genes in rat brain after kainic acid-induced seizures

Kainic acid-induced seizures in the rat brain cause severe brain damage that is thought to result, in part, from oxidative stress. In this study, we examine the consequences of systemic administration of kainic acid on expression of several genes that encode proteins thought to play roles in protection from oxidative stress, including metallothionein-I, and -III. Kainic acid causes an increase in metallothionein-I and heme oxygenase-I mRNAs, as well as an increase in c-fos, heat shock protein-70, and interleukin-1 beta mRNAs. The induction of these mRNAs is seizure dependent, and is greater in brain areas with extensive damage (e.g. piriform cortex) than in areas with minimal damage (e.g. frontal cortex and cerebellum). In contrast, little or no change in mRNA for metallothionein-III, manganese superoxide dismutase, copper-zinc superoxide dismutase, glutathione-s-transferase ya subunit or glutathione peroxidase occur. The prolonged and robust concordant induction of the metallothionein-I and heme oxygenase-I genes may reflect the oxidative stress produced by kainic acid-induced seizures. In addition, the induction of interleukin-1 beta gene expression suggests an inflammatory response in brain regions damaged by kainic acid-induced seizures. Delineating the regulation of genes associated with oxidative and inflammatory responses can contribute to a fuller understanding of seizures and associated brain damage.

Transcriptional induction of the mouse metallothionein-I gene in hydrogen peroxide-treated Hepa cells involves a composite major late transcription factor/antioxidant response element and metal response promoter elements

Synthesis of metallothionein-I (MT-I) and heme oxygenase mRNAs is rapidly and transiently induced by H2O2 in mouse hepatoma cells (Hepa) and this effect is blocked by catalase. Menadione, which generates free radicals, also induces these mRNAs. Deletion mutagenesis revealed that a region between -42 and -153 in the mouse MT-I promoter was essential for induction of a CAT reporter gene. A multimer of a 16 bp sequence (-101 to -86) that includes an antioxidant response element and overlapping adenovirus major late transcription factor binding site elevated basal expression and allowed induction by H2O2 when inserted upstream of a minimal promoter. However, deletion of this region (-100 to -89) from the intact MT-I promoter (-153) did not completely eliminate response. Multiple copies of a metal response element also permitted response to H2O2. These results suggest that induction of MT-I gene transcription by H2O2 is mediated by at least two different elements within the proximal MT-I gene promoter and suggest a previously undescribed function of the MRE. Induction of MT gene transcription by ROS and the subsequent scavenging of ROS by the MT peptide is reminiscent of the metal regulatory loop and is consistent with the hypothesized protective functions of MT.

Analysis of the expression of growth factor, interleukin-1, and lactoferrin genes and the distribution of inflammatory leukocytes in the preimplantation mouse oviduct

The oviduct provides the environment in which fertilization of the egg and subsequent development of the preimplantation mouse embryo occurs, but little is known about the oviduct's capacity to produce growth factors or cytokines that may influence these preimplantation events. Northern blot analysis and/or immunohistochemistry were employed to examine the expression or cellular distribution, respectively, of the growth factors heparin-binding epidermal-like growth factor (HB-EGF), transforming growth factor (TGF) alpha, epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), TGF beta 1, TGF beta 2, and TGF beta 3; of estrogen-regulated lactoferrin (LF); and of the cytokines interleukin (IL)-1 alpha and IL-1 beta in the mouse oviduct during the preimplantation period (Days 1-4 [Day 1 = vaginal plug]) and 7 days after ovariectomy. The results demonstrated that, except for EGF, each of the growth factors and the LF genes are expressed in the ampulla and isthmus regions of the oviduct throughout the preimplantation period. Prominent immunostaining in secretory epithelial cells was noted for HB-EGF, TGF alpha, IGF-I, TGF beta 1, and TGF beta 2, and LF. Less intense immunostaining in the serosa and/or smooth muscle was also noted for TGF alpha, IGF-I, and TGF beta 1. In contrast, intense immunostaining in smooth muscle was noted for TGF beta 2, and TGF beta 3 was detected exclusively in smooth muscle cells. The abundance of these mRNAs was relatively constant during the preimplantation period, and ovariectomy did not reduce the levels of these mRNAs. In contrast to these growth factors, the cytokine mRNAs examined (IL-1 alpha and IL-1 beta) were at or below the limits of detection under these experimental conditions, and inflammatory leukocytes (LF-immunopositive neutrophils, IL-1 beta-immunopositive monocytes/macrophages, or peroxidase-positive eosinophils) were not detected in the oviduct, but were abundant in the adjacent uterine stroma on Day 1. These studies show that several growth factors are synthesized by the mouse oviduct and suggest that ovarian steroids do not play a major role in modulating expression of these genes in the oviduct during the preimplantation period. Furthermore, unlike the uterus on Day 1, the oviduct does not exhibit an inflammatory response to mating.

Profile of prostatic-specific antigen in prostatic carcinomas

Prostatic carcinomas (PCs) may be divided into two distinct categories: latent PCs, found mostly at autopsy, and clinical cases, which present with signs and symptoms. These two categories correspond fairly well to histologic grading of PCs and immunoperoxidase staining for prostatic specific antigen (PSA). The objective of this study was to find quantitative and qualitative differences if any, of PSA in PCs, corresponding to Gleason's histologic grade. By radiometric assay of PSA in tissue cytosol, PCs especially those of high histologic grade, were found to have lower PSA concentrations than normal and glandular hyperplastic prostatic tissue. Western blotting of cytosol was performed to detect differences between immunoreactive PSA of PCs compared with noncancerous tissue using both polyclonal and monoclonal antibodies against PSA. Western blotting with anti-PSA revealed some different bands between cancerous and noncancerous cytosols. Western blotting of cancerous and noncancerous cytosols was also performed using anti-prostatic acid phosphatase and anti-beta micro-seminoprotein. Reduced PSA concentration and different immunoblotting pattern of PSA were found to be characteristic for PCs, especially in carcinomas with grades higher than 7, which usually present with more aggressive invasion and metastases.

Improved patient selection for angioplasty utilizing color Doppler imaging

The accepted approach to patients with intermittent calf claudication is nonoperative unless the symptoms are truly incapacitating, in which case arteriography and either percutaneous angioplasty or operation is indicated. Arteriography is considered a preoperative procedure. However, with improvements in percutaneous angioplasty, we have altered our approach to those patients with limiting, but not incapacitating, claudication. These patients are given the choice of conservative treatment or percutaneous angioplasty, but not operation. In an attempt to limit arteriography to only those patients who would benefit from angioplasty, we have employed color Doppler imaging as a screening technique. Over a 2-year period, 62 patients with limiting claudication were evaluated with color Doppler imaging. Thirty-six patients had long occlusions and did not undergo arteriography since they were not believed to be candidates for percutaneous angioplasty. Three short (less than 5 cm) occlusions and 23 localized stenoses were identified in the superficial femoral and popliteal arteries. Angiography confirmed the Doppler findings in all 26 cases. In 24 patients, dilatation was successful, whereas 2 patients' arteries could not be dilated. Two stenoses recurred early and were redilated. There were no complications from the angioplasties. We conclude that in the subset of patients with limiting, but not incapacitating, claudication, color Doppler imaging can accurately select those patients who will benefit from angioplasty. In this way, patients can be spared unnecessary angiograms.

Receptor turnover and the action of 5-hydroxytryptamine on the salivary glands of the blowfly Calliphora erythrocephala, the housefly Musca domestica and frog skin epithelium

1. Continual stimulation of frog skin epithelium and the salivary glands of the insects Calliphora and Musca with 5-hydroxytryptamine (5-HT) leads to desensitisation, i.e. the tissue fails to respond to the application of further 5-HT. 2. Incubation of desensitised frog skin and Musca salivary glands with either N-acetyl neuraminic acid or inositol partially restored the 5-HT responses whilst incubation with a combination of N-acetyl neuraminic acid and inositol gave additive effects on the recovery of the 5-HT responses. 3. Incubation of desensitised salivary glands of Calliphora with inositol totally restored the 5-HT response whilst incubation with N-acetyl neuraminic acid had no effect. 4. It is concluded that desensitisation involves depletion of secondary messenger from the tissues coupled with receptor degradation and that considerable differences exist in the turnover of 5-HT receptors, the receptors in Musca salivary glands being highly labile, those in Calliphora salivary glands highly stable and those of frog skin epithelium being intermediate in their stability.

Cell-mediated inhibition of tumor colony formation in agarose by resting and interleukin 2-stimulated human lymphocytes

Human nonadherent peripheral blood mononuclear cells (PBMC) isolated from nonimmunized donors were preincubated for 18 h in medium alone or medium containing the lymphokine interleukin 2 and subsequently cocultured with tumor cells derived from malignant tumor cell lines or from fresh human tumors. The cell suspensions were subsequently inoculated into agarose; 14 days later, new tumor colony formation was determined. Although the different tumor cells displayed a wide range of sensitivity to the PBMC, in each instance, the number of colonies formed by the tumor cells exposed to the PBMC was consistently reduced relative to that of control cells. The inhibitory effect on the colony-forming cells was especially pronounced with PBMC preincubated with interleukin-2 and was dependent on the ratio of tumor cells to PBMC in the culture. This assay system provides an alternative to the standard 51Cr release assays in assessing the immunomodulatory effects of lymphokines and in quantitating the cytolytic or cytostatic activity of various effector cells against neoplastic stem cells from established cell lines and from heterogeneous cell preparations derived from fresh human tumors.

Estrogen and progesterone receptors in meningiomas

Two-thirds of all meningiomas and four-fifths of intraspinal and sphenoidal meningiomas occur in women. Meningiomas frequently enlarge or become symptomatic during pregnancy or during the luteal phase of the menstrual cycle. There is an increased incidence of meningiomas in women with breast carcinoma. In a series of 23 patients with meningiomas, the authors assayed biopsy specimens of the tumor for the presence of estrogen (ER) and progesterone (PR) receptors, using glycerol density gradient centrifugation and dextran-coated charcoal techniques. Significant levels of ER were found in only 17% of the patients, while significant PR levels were detected in 39%. Only one of the 16 tumors from female patients had significant ER levels, whereas three of the seven tumors from men had significant ER levels. Eight of the 16 tumors in women had significant PR levels, whereas only one of the seven tumors in men had a significant PR level. Thus, three out of four tumors with definite ER were from men, whereas eight of nine tumors with definite PR were from women. Of the eight women whose tumors contained PR, three were premenopausal and five postmenopausal. The single tumor with high levels of PR in the male patient was histologically atypical. The results of this series were compared with six published series of sex steroid assays in meningiomas. These seven series were divided into two groups: one group included two reports from the same laboratories in France, and the other the remaining five reports. Much higher percentages of both ER- and PR-positive tumors were reported from the French group. The authors suggest that this discrepancy may be due to the use of preoperative glucocorticoid therapy in the series from the United States. Since meningiomas are known to enlarge during periods when levels of circulating progestins are high, the presence of significant quantities of PR in a high percentage of tumors may have therapeutic implications for recurrent, malignant, or incompletely excised tumors, or for medically fragile patients. Conversely, since meningiomas are not known to enlarge during the proliferative phase of the menstrual cycle or with exogenous estrogen therapy, the small number of tumors positive for ER may indicate that ER lacks clinical significance. High levels of PR found in a small group of histologically aggressive tumors in several series may indicate that hormonal therapy may be especially useful in this difficult subset of patients.

Selective destruction of 5-hydroxytryptamine receptors by neuraminidase

The responses of isolated frog skin to 5-hydroxytryptamine (increased active sodium transport and decreased passive chloride permeability) are diminished by incubation with the enzymes neuraminidase and N-acetylneuraminic acid aldolase but only in the absence of Ca2+ and presence of EDTA. The responses induced by oxytocin, adrenalin and aldosterone are unaffected by enzyme treatment.

Pharmacology of 5-hydroxytryptamine receptors in frog skin epithelium

1. 5-Hydroxytryptamine (5-HT) stimulates active sodium transport and decreases the passive mucosal to serosal chloride permeability across frog skin. The relative importance of the different regions of the 5-HT molecule in the mediation of these responses has been studied using a range of structurally related compounds. 2. Substitution in the ethyl amine side chain of 5-HT (5-hydroxytryptophan) results in decreased receptor affinity and intrinsic activity; removal of the side chain (5-hydroxyindole) abolishes activity. Methoxy substitution of the 5-OH moiety of 5-HT has no effect on intrinsic activity but reduces affinity; displacement of the hydroxyl group to position 6 diminishes intrinsic activity and affinity. 3. It is concluded that both of the 5-HT-induced physiological effects are mediated via a single receptor which is distinct from alpha- and beta-adrenoceptors.

The loss of biological activity of 5-hydroxytryptamine creatinine sulphate

5-Hydroxytryptamine creatinine sulphate loses its biological activity when maintained at room temperature. The loss of 5-HT activity (in stimulating sodium transport across frog skin) is greater than the loss of creatinine sulphate activity (inhibition of sodium transport).

Respiratory and enzymic changes in response to steroid hormones

Changes in respiration and enzymic activity were measured in toad bladder tissue and homogenates in response to aldosterone and in rat liver tissue and homogenates in response to corticosterone. The results showed that the stimulation of target tissue may be associated with the saturation of two types of receptor sites for these hormones. The mechanism of action of both hormones is discussed in terms of a common effect on the control of respiration of the target tissue, and a second effect on the control of cellular processes such as the entry of sodium into the epithelial cells of toad bladder or increased transaminase activity in rat liver.