Age-related changes in angiotensin II-stimulated vascular contraction and inositol phosphate accumulation in Fischer 344 rats

This study examined the influence of age on angiotensin II (AII)-stimulated vascular contractile responses and inositol phosphate (IP) accumulation in Fischer 344 rats. In the aorta, AII-stimulated contraction and IP accumulation were markedly reduced in 6- and 24-month-old rats compared to 1-month-old rats. There was not a significant difference in the contractile response to AII between 6- and 24-month-old rats, although IP hydrolysis showed a further decrease between 6 and 24 months. In tail artery, there were no differences in contraction and phosphoinositol metabolism in response to AII in the different ages. Losartan blocked AII-stimulated vascular contraction and IP hydrolysis in both aorta and tail artery while PD123319 did not inhibit either response. These data indicate that during maturation, there is a decline in AII-stimulated aortic contraction and IP accumulation in aorta but not in tail artery and these changes are due to altered AT1 receptor function.

Targeted disruption of the Hexa gene results in mice with biochemical and pathologic features of Tay-Sachs disease

Tay-Sachs disease, the prototype of the GM2 gangliosidoses, is a catastrophic neurodegenerative disorder of infancy. The disease is caused by mutations in the HEXA gene resulting in an absence of the lysosomal enzyme, beta-hexosaminidase A. As a consequence of the enzyme deficiency, GM2 ganglioside accumulates progressively, beginning early in fetal life, to excessive amounts in the central nervous system. Rapid mental and motor deterioration starting in the first year of life leads to death by 2-4 years of age. Through the targeted disruption of the mouse Hexa gene in embryonic stem cells, we have produced mice with biochemical and neuropathologic features of Tay-Sachs disease. The mutant mice displayed < 1% of normal beta-hexosaminidase A activity and accumulated GM2 ganglioside in their central nervous system in an age-dependent manner. The accumulated ganglioside was stored in neurons as membranous cytoplasmic bodies characteristically found in the neurons of Tay-Sachs disease patients. At 3-5 months of age, the mutant mice showed no apparent defects in motor or memory function. These beta-hexosaminidase A-deficient mice should be useful for devising strategies to introduce functional enzyme and genes into the central nervous system. This model may also be valuable for studying the biochemical and pathologic changes occurring during the course of the disease.

Murine model of otitis media with effusion: immunohistochemical demonstration of IL-1 alpha antigen expression

Recent studies have suggested that cytokines likely play a central role in the formation and maintenance of otitis media with effusion (OME). Currently, there is no immunologically defined animal model for the study of cytokines as they contribute to the formation of OME. In the present study, a murine model of OME, using eustachian tube blockage via an external surgical approach, was developed. The murine model temporal bone histology appears to mimic the histology found in chronic otitis media with effusion in humans. Additionally, using this murine model, interleukin-1 alpha (IL-1 alpha) expression was detected in the middle ear using standard immunohistochemical techniques. IL-1 alpha seemed localized to the epithelial lining of the middle ear as well as 5% to 10% of inflammatory cells. This model should provide the necessary tool to further study the immunologic aspects of OME.

Indolent granulomatous angiitis. Case report

Granulomatous angiitis is a rare, treatable central nervous system vasculitis. Prompt diagnosis may be thwarted by protean presenting symptoms, an indolent clinical course, and atypical neurological findings. The authors describe a case of indolent granulomatous angiitis in which the patient presented with cerebellar signs and tissue changes suggestive of an atypical cerebellar infarction. After several years of remissions and relapses, repeat evaluation and biopsy disclosed granulomatous angiitis both in remote infarctions and in new cortical lesions. The clinical course and neuroradiological and pathological findings are compared with previous reports of fulminant and indolent granulomatous angiitis.

Solubilization of a tripeptide HIV protease inhibitor using a combination of ionization and complexation with chemically modified cyclodextrins

Kynostatin (KNI-272), an experimental HIV protease inhibitor, is currently undergoing preclinical testing for the treatment of AIDS. This transition state mimetic tripeptide exhibits extremely low aqueous solubility (4 micrograms/mL) making target concentrations (5-50 mg/mL) for parenteral solution formulations difficult to achieve. The presence of an ionizable (5-isoquinolinyloxy)acetyl moiety makes solubilization via pH adjustment possible, but a solubility > 5 mg/mL requires an adjustment in pH below 2.0, which would be physiologically unacceptable. This study examines and compares two approaches for solubilizing kynostatin: (1) inclusion complex formation at chemically distinct hydrophobic binding sites using (2-hydroxypropyl)-beta-cyclodextrin (HPCD) and a sulfobutyl ether derivative of beta-cyclodextrin (beta-CD-SBE) and (2) a combined strategy utilizing ionization of the isoquinoline moiety coupled with inclusion complex formation at the remaining binding site(s). Macroscopic binding constants determined from solubility profiles as a function of pH and HPCD concentration have been compared with the microscopic binding constant for formation of the isoquinoline-HPCD inclusion complex determined by UV difference spectroscopy to examine the independence of binding domains within KNI-272. As demonstrated in this report, combination strategies tailored to the properties of different domains within the molecule may be highly effective in solubilizing compounds such as poorly soluble peptides.

Isoform specific interactions of troponin I and troponin C determine pH sensitivity of myofibrillar Ca2+ activation

We investigated whether differences in isoforms of troponin I (TnI) and troponin C (TnC) can account for the greater inhibition of Ca(2+)-dependent MgATPase activity by acidic pH in cardiac (c) than in fast skeletal (fs) myofilaments. We studied fast skeletal myofibrils from which whole Tn was extracted by displacement with excess fsTnT (the tropomyosin binding subunit of Tn) followed by reconstitution with TnC-TnI. Exchange of fsTnI with cTnI did not alter the effect of a drop in pH from 7.0 to 6.5 on the relation between pCa (-log[Ca2+]) and MgATPase activity of fast skeletal myofibrils. Exchange of fsTnC with cTnC did, however, induce an increase in the effect of this same pH change on Ca2+ activation. Yet, the pH sensitivity of Ca2+ activation of fast skeletal myofibrils containing cTnC was not as great as that of native cardiac myofibrils. However, when both fsTnC and fsTnI of fast skeletal myofibrils were replaced by cTnC-cTnI, there was a pH-induced shift in Ca2+ sensitivity similar to that of cardiac myofibrils. In studies using fluorescent probes, both pure fsTnC and pure cTnC showed decreased Ca2+ binding as pH was lowered. This decrease was potentiated in the fsTnC-fsTnI and cTnC-cTnI complexes. However, the effect of acidic pH was the same in fsTnC and the hybrid complex, fsTnC-cTnI, and in cTnC and the hybrid complex, cTnC-fsTnI. Thus, isoform specific interactions between TnI and TnC appear important in the differential response of skeletal and cardiac myofilaments to acidosis.

Plasmid-directed assembly of the lipid-containing membrane of bacteriophage phi 6

The nucleocapsid of bacteriophage phi 6 is enveloped within a lipid-containing membrane. The membrane is composed of proteins P3, P6, P9, P10, and P13 and phospholipids. The relationship between membrane protein P9 and morphogenetic protein P12 was studied in the absence of phage infection. cDNA copies of genes 9 and 12 were expressed on plasmids in Pseudomonas syringae pv. phaseolicola. Immunoblotting demonstrated the presence of protein P9 in strains carrying both gene 9 and gene 12 but not in strains with gene 9 alone. In the absence of P12, P9 was found to be unstable. Simultaneous synthesis of proteins P9 and P12 led to the formation of a low-density P9 particle having a buoyant density similar to that of precursor structures composed of phospholipid and proteins isolated from phi 6-infected cells. These results are consistent with results of previous genetic experiments suggesting that P9 and P12 are necessary and sufficient for the formation of the phi 6 envelope. Extensions of P9 at the C terminus do not impair particle formation; however, N-terminal extensions or C-terminal deletions that extend into the hydrophobic region of P9 do impair particle formation.

Inhibition of angiogenesis by tissue inhibitor of metalloproteinase

Matrix proteases play a critical role in cell invasion and migration, including the process of angiogenesis. The ability of specific factors to induce angiogenic responses correlates with their stimulation of matrix protease synthesis and release. Using an in vivo angiogenesis assay, the endothelial cell response to known angiogenic factors, basic fibroblast growth factor (bFGF) and adipocyte conditioned medium, was blocked by an inhibitor of matrix metalloproteinase activity, TIMP-1. The TIMP effect was mediated, at least in part, through the inhibition of endothelial cell migration, as determined by the ability of TIMP to block chemotaxis in a Boyden chamber assay. These results indicate that the inhibition of migration is a direct effect on the endothelial cells and does not require accessory cells. An additional observation was that the RNA levels for TIMP were significantly reduced in differentiated adipocytes, compared to undifferentiated F442A controls. Therefore, the acquisition of an angiogenic phenotype may involve not only the induction of positive factors, but also the suppression of angiogenesis inhibitors.

Disordered eating in active and athletic women

In an attempt to improve athletic performance, some female athletes develop patterns of disordered eating. The spectrum of disordered eating ranges from mild to severe, with the severe form resulting in anorexia nervosa or bulimia nervosa. Disordered eating can result in decreased athletic performance, increased morbidity, and occasional mortality.

Isolation and characterization of nonsense mutations in gene 10 of bacteriophage phi 6

Nonsense mutants of bacteriophage phi 6 were isolated by a procedure that involved directed mutagenesis of a cDNA copy of genomic segment M, transcription of this segment, in vitro packaging into procapsids, and transfection of spheroplasts to form viable mutant phage. Recombinant phi 6 viruses that contained amber mutations in two open reading frames, ORF 10 and ORF D, of genomic segment M were isolated. We show that phi 6 protein P10 is the gene product of ORF 10. Further characterization of the phi 6 ORF 10(Am) mutant revealed that phi 6 membrane-associated protein P10 is not required to make enveloped phage particles in infected cells. Enveloped phage particles isolated from a phi 6 ORF 10(Am) infection contained extremely low levels of phi 6 membrane-associated proteins P6 and P3. The low abundance is due to the very low level of P6 synthesis in phi 6 ORF 10(Am)-infected cells. The results suggest that P10 might play a role in regulating the translation of gene 6. Protein P10 was found to be required for host lysis.

Cytokines in experimental otitis media with effusion

Studies in the authors' laboratory have recently demonstrated the presence of potent inflammatory cytokines such as interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF alpha) in human middle ear effusions. The clinical significance of this finding has not been fully elucidated because of the limitations of human studies. We hypothesized that the chinchilla model of otitis media may be an appropriate system with which to study the role of cytokines in otitis media with effusion. To begin to investigate this possibility, 30 chinchillas underwent surgical blockage of the eustachian tube (ET) to promote effusion development. After 2 weeks, examination by otoscopy demonstrated 27 ears to have developed an effusion. Next, all middle ear clefts, in random manner, were either injected with heat-killed Streptococcus pneumoniae 1 x 10(6) in 0.1 mL normal saline, injected with 0.1 mL normal saline alone, or received no injection at all. Middle ear effusions were obtained and analyzed for IL-1 beta and TNF alpha by enzyme-linked immunosorbent assay (ELISA). This study demonstrated a significant correlation between IL-1 beta and the presence of an effusion (P < .001). Additionally, increased TNF alpha levels correlated with bacterial component presence (P < .001), i.e., mean TNF alpha level was 108, 10.8, and 0 pg/mL in bacteria, normal saline, and noninjected ears, respectively. These findings would suggest that cytokine expression may relate to specific pathological conditions and that the chinchilla model for otitis media with effusion (OME) could be used to further explore the role of cytokines in OME.

The epidermal growth factor receptor is associated with phospholipase C-gamma 1 in meningiomas

In this study we evaluated phospholipase C-gamma 1 (PLC-gamma 1) expression, activity, and association with the epidermal growth factor (EGF) receptor in a series of human meningiomas as well as cultured meningioma cells. Phospholipase C-gamma 1 was detectable by immunoblot and immunohistochemistry in 13 of 13 meningioma specimens. Epidermal growth factor receptors were detected by immunoblot in six of nine meningiomas (67%) and by immunohistochemistry in 13 of 19 meningiomas (68%) but not in normal leptomeningeal cells. In two of three meningiomas EGF receptors and/or a 170-kd phosphotyrosine band precipitated with a PLC-gamma 1 antiserum. Both PLC-gamma 1 and EGF receptors also exhibited the same pattern of immunostaining on meningioma tissue sections. Phospholipase C-gamma 1 catalytic activity, measured in a PIP2 hydrolysis assay, was higher in nine EGF receptor-positive meningiomas than in six EGF receptor-negative meningiomas (P = .05; t test). Finally, treatment of cultured meningioma cells with transforming growth factor-alpha induced a 78% increase in PLC-gamma 1 catalytic activity. Thus, these data are consistent with the possibility that the EGF receptor tyrosine kinase regulates PLC-gamma 1 activity in native meningioma tissue.

Synaptic glutamate release by postnatal rat serotonergic neurons in microculture

Serotonergic neurons are thought to play a role in depression and obsessive compulsive disorder. However, their functional transmitter repertoire is incompletely known. To investigate this repertoire, intracellular recordings were obtained from 132 cytochemically identified rat mesopontine serotonergic neurons that had re-established synapses in microcultures. Approximately 60% of the neurons evoked excitatory glutamatergic potentials in themselves or in target neurons. Glutamatergic transmission was frequently observed in microcultures containing a solitary serotonergic neuron. Evidence for co-release of serotonin and glutamate from single raphe neurons was also obtained. However, evidence for gamma-aminobutyric acid release by serotonergic neurons was observed in only two cases. These findings indicate that many cultured serotonergic neurons form glutamatergic synapses and may explain several observations in slices and in vivo.

Matrix-degrading proteases in hormone-dependent breast cancer

Proteases have emerged as important modulators of the metastatic capacity of cancer. However, metastasis is regulated by multiple other characteristics of the tumor cell and evidence suggests the participation of multiple classes of proteases. In the present article we review the literature concerning the potential biological roles of multiple proteases in breast cancer. In particular, we focus on the gelatin-degrading metallo proteinase and on a novel 80 KDa matrix-degrading protease that appears to be commonly expressed in hormone dependent breast cancer cell lines.

Binding of Nitrogen Heterocyclic Ligands and Tetraphenyl-Substituted Ions by β-Cyclodextrins

Binding constants obtained spectrofluorometrically are reported for β- cyclodextrin (substituted and unsubstituted ) inclusion of several commonly used nitrogen heterocyclic ligands and tetraphenyl-substituted ions.

Prenatal cocaine exposure affects the development of aortic adrenergic innervation and contractile responses

This study examines the effects of prenatal cocaine administration on the development of vascular sympathetic innervation and contractile responsiveness. Rabbits received cocaine (4 mg/kg, iv, bid) or saline during gestational days 8 to 29. Aortas were obtained on postnatal days 10, 20, 30 and 50. Vascular smooth muscle responsiveness was assessed by measuring aortic contractile responses to norepinephrine (NE) and to other vasoconstrictors. Vascular adrenergic innervation was evaluated by measuring desipramine sensitive [3H]-NE uptake into aortic ring segments and aortic NE content. [3H]-NE uptake and NE content were reduced at postnatal days 10 and 20 in the rabbits exposed prenatally to cocaine. Differences were not observed at postnatal days 30 or 50. The contractile response to NE was reduced in rabbits exposed to cocaine prenatally. Maximal response and potency were decreased at postnatal day 10 and potency was still decreased at day 20, but not at the older ages. Contractile responses to serotonin (5-HT) and angiotensin II (AII) were not affected by prenatal cocaine exposure. These results suggest that prenatal cocaine exposure delays the development of aortic adrenergic innervation and alpha adrenoceptor responsiveness.

Maintenance of training effects on the Wisconsin Card Sorting Test by patients with schizophrenia or affective disorders

The authors used the Wisconsin Card Sorting Test to study 50 hospitalized psychiatric patients: 28 with schizophrenia, 17 with affective disorders, and five with schizoaffective disorder. The schizophrenic patients performed significantly more poorly than the patients with affective disorders. Both groups of patients improved when given additional instructions. The schizophrenic patients maintained their improvement when retested approximately 6 weeks later. The results suggest that factors other than frontal cortex dysfunction are involved in schizophrenic patients' performance on the Wisconsin Card Sorting Test.

Inhibition of mammary duct development but not alveolar outgrowth during pregnancy in transgenic mice expressing active TGF-beta 1

The transforming growth factors beta (TGFs-beta) are potent inhibitors of cell proliferation and are usually secreted in a latent form. TGF-beta 1, TGF-beta 2, and TGF-beta 3 are expressed in distinct but overlapping patterns in the developing mouse mammary gland. To study the role of transforming growth factor-beta 1 (TGF-beta 1) in normal mammary development and in mammary neoplasia, we have constructed three transgenic mouse lines that express a simian TGF-beta 1 s223/225 mutated to produce a constitutively active product under the control of the MMTV enhancer/promoter. Expression of the transgene, as confirmed by in situ hybridization, immunohistochemistry, and Northern blot analysis, was associated with marked suppression of the normal pattern of mammary ductal tree development in female transgenics. Reduction in total ductal tree volume was observed at 7 weeks, soon after estrous begins, and was most apparent at 13 weeks, as ductal growth in the normal mammary gland declines. This effect was seen in all three lines. However, during pregnancy, alveolar outgrowths developed from the hypoplastic ductal tree, and lactation occurred, therefore, all transgenic females could feed full litters. Unlike many other transgenic mouse models in which expression of growth factors or oncogenes under control of the MMTV promoter leads to mammary epithelial hyperplasia and increased tumor formation, the MMTV-TGF-beta 1S223/225 transgene causes conditional hypoplasia of the mammary ductal tree and no spontaneous tumors have been detected in the MMTV-TGF-beta 1S223/225 transgenic animals.

Anti-transforming growth factor (TGF)-beta antibodies inhibit breast cancer cell tumorigenicity and increase mouse spleen natural killer cell activity. Implications for a possible role of tumor cell/host TGF-beta interactions in human breast cancer progression

TGF-beta effects on angiogenesis, stroma formation, and immune function suggest its possible involvement in tumor progression. This hypothesis was tested using the 2G7 IgG2b, which neutralizes TGF-beta 1, -beta 2, and -beta 3, and the MDA-231 human breast cancer cell line. Inoculation of these cells in athymic mice decreases mouse spleen natural killer (NK) cell activity. Intraperitoneal injections of 2G7 starting 1 d after intraperitoneal inoculation of tumor cells suppressed intraabdominal tumor and lung metastases, whereas the nonneutralizing anti-TGF-beta 12H5 IgG2a had no effect. 2G7 transiently inhibited growth of established MDA-231 subcutaneous tumors. Histologically, both 2G7-treated and control tumors were identical. Intraperitoneal administration of 2G7 resulted in a marked increase in mouse spleen NK cell activity. 2G7 did not inhibit MDA-231 primary tumor or metastases formation, nor did it stimulate NK cell-mediated cytotoxicity in beige NK-deficient nude mice. Finally, serum-free conditioned medium from MDA-231 cells inhibited the NK cell activity of human blood lymphocytes. This inhibition was blocked by the neutralizing anti-TGF-beta 2G7 antibody but not by a nonspecific IgG2. These data support a possible role for tumor cell TGF-beta in the progression of mammary carcinomas by suppressing host immune surveillance.

Neoplastic meningitis as the presentation of occult primitive neuroectodermal tumors

Seven children and young adults initially presented with subacute meningitis and/or increased intracranial pressure. The diagnosis of neoplastic meningitis secondary to a primitive neuroectodermal neoplasm was delayed by the absence of an obvious primary tumor. The neuroradiologic appearance was that of a basimeningeal infiltrative process, complicated by communicating hydrocephalus or "pseudotumor cerebri." Myelography was important in the diagnosis of disseminated meningeal malignancy in four cases. Cerebrospinal fluid cytologic diagnosis was insensitive but ultimately confirmed in five cases. All seven patients experienced progressive disease despite neuraxis radiotherapy and intensive chemotherapy; six have died. Systemic dissemination to bone and/or peritoneum occurred in three patients while on therapy. In two, a primary parenchymal brain or spinal cord tumor could not be identified at postmortem examination. The presentation of a primitive neuroectodermal tumor as subacute meningitis without an evident primary tumor heralds an aggressive and refractory neoplasm.

Keys to Successful Preparticipation Exams

Timing, frequency, and types of screening tests can be hot topics of debate among physicians trying to determine how best to evaluate patients for athletic participation. Because of the wide range of opinions concerning many elements of preparticipation physical exams, we brought together three medical experts to discuss a few important aspects of these screenings.

Detection of genes that are differentially expressed during mouse embryogenesis by genetic trapping strategies

OBJECTIVE

Our objective was to identify novel genes that are expressed in temporally and spatially restricted patterns during mouse embryonic development and organogenesis.

STUDY DESIGN

Two genetic trapping reporter constructs that lack transcriptional regulatory sequences were introduced independently into transcriptionally active gene loci by electroporation into mouse embryonic stem cells. Patterns of host gene-reporter construct expression were investigated in differentiated embryonic stem cells, embryoid bodies, and chimeric embryos at various stages of development.

RESULTS

Three patterns of host gene-reporter construct expression were observed from the developmental analysis of four vector-integrated cell lines. Reporter expression patterns reflecting developmental regulation, constitutive activity, and developmental inactivation of the host genes were observed.

CONCLUSIONS

Two vector-integrated gene loci from cell lines CCE-1C1 and D3-B44 have expression patterns not previously described by genetic trapping. Molecular characterization of these interrupted genes will shed light on their developmental function.

T cell development in mice that lack the zeta chain of the T cell antigen receptor complex

The zeta subunit of the T cell antigen receptor complex is required for targeting nascent receptor complexes to the cell surface and for receptor-mediated signal transduction. To examine the significance of the zeta subunit in T cell development, mice deficient for zeta expression were generated by gene targeting. These zeta-/- mice had few CD4+CD8+ thymocytes, and the generation of CD4+ and CD8+ single positive T cells was impaired but not completely abrogated. Peripheral T cells were present but were unusual in that they expressed small amounts of CD5 and few T cell receptors. Thus, zeta chain expression influences thymocyte differentiation but is not absolutely required for the generation of single positive T cells.

General anesthesia for cesarean section in a parturient with a single ventricle and pulmonary atresia

The successful management of a cesarean section in a parturient with a single ventricle and pulmonary atresia using general anesthesia is discussed. After cyanosis at birth, the patient underwent cardiac catheterization, which showed an apparent severe tetralogy of Fallot, atresia of the main pulmonary artery (PA), and a large patent ductus arteriosus. When she was 7 months of age, a Blalock-Taussig shunt (right subclavian artery to right PA) was done. She remained stable until age 11, when cyanosis increased and exercise tolerance decreased. Recatheterization more clearly defined the lesion: closed shunt, pulmonary valvular atresia, severe ductal stenosis, reduced pulmonary flow, double-outlet right ventricle, and severe hypoplasia of the left atrium, mitral valve, and left ventricle. A Potts shunt (left descending aorta to left PA) was done. Compliance with therapy was poor and follow-up difficult. Exercise tolerance was poor, but the patient remained otherwise stable. At 28 weeks' gestation, this 23-year-old parturient presented with severe congestive heart failure (CHF). After initial therapy with oxygen, bed rest, digoxin, and diuretics, she improved and remained stable for a month. At that time (32 weeks' gestation), CHF worsened. Because the cervix was unfavorable for a vaginal delivery, a cesarean section was planned. The patient was then taken to the operating room electively, and an opioid-based general anesthetic was administered. Both mother and infant did well. This case is presented because the physiology of the patient's lesion and her unusual social history presented challenges for her anesthetic management.

Localization of NADPH diaphorase activity in monoaminergic neurons of the rat brain

Nitric oxide has recently been implicated as a neurotransmitter, and may modulate synaptic transmission, cerebral blood flow, and neurotoxicity. NADPH diaphorase histochemistry has been shown to be a reliable marker for nitric oxide synthase, the enzyme that synthesizes nitric oxide, in the nervous system. Because monoaminergic neurons frequently contain co-transmitters, we examined whether these cells also exhibit NADPH diaphorase activity. Frozen sections from postnatal and adult rat brains were stained for NADPH diaphorase activity and either serotonin-like immunoreactivity or tyrosine hydroxylase-like immunoreactivity. Numerous neurons in the mesopontine serotoninergic cell groups (including the caudal linear, dorsal, median, supralemniscal, and pontine raphe nuclei) contained both serotonin-like immunoreactivity and NADPH diaphorase activity. Within the dorsal raphe nucleus, approximately 70% of the serotoninergic neurons in the medial subnuclei displayed NADPH diaphorase activity, while less than 10% of the serotoninergic neurons in the lateral subnuclei were doubly labeled. Retrograde labeling with fluorescent microspheres indicated that many raphe-cortical neurons contained NADPH diaphorase activity. No NADPH diaphorase activity was detected in serotoninergic neurons in the medullary nuclei (including the raphe magnus, raphe pallidum, and raphe obscurus). Only a small proportion of tyrosine hydroxylase-like immunoreactive neurons in the periaqueductal gray, rostral linear nucleus, and rostrodorsal ventral tegmental area contained NADPH diaphorase activity. Tyrosine hydroxylase-like immunoreactive neurons in the substantia nigra, locus coeruleus, hypothalamus, olfactory bulb, and dorsal raphe nucleus did not contain detectable NADPH diaphorase activity. The observation that many mesopontine (but not medullary) serotoninergic neurons contain NADPH diaphorase activity suggests that these neurons may release both serotonin and nitric oxide.

Sucrose does not raise blood pressure in rats maintained on a low salt intake

Diets high in sucrose or fructose have been shown by others to induce a modest elevation of blood pressure in rats. The present experiments were conducted to determine whether the sucrose-induced increase of blood pressure is dependent on the intake of sodium chloride. Four groups of Sprague-Dawley rats were studied: 1) a group maintained on a low salt diet and distilled water (0.45% sodium chloride, no added sucrose), 2) a low salt-high sucrose group (0.45% sodium chloride diet and 7% sucrose in distilled water), 3) a high salt group (4% sodium chloride diet and distilled water), and 4) a high salt-high sucrose group on a diet adjusted daily to maintain the same high intakes of sodium chloride and sucrose as those of groups 2 and 3. Systolic blood pressures were measured by tail-cuff plethysmography during weeks 1-3 of treatment, and direct mean arterial blood pressures were recorded in conscious animals during week 4. Animals on the high salt diet gained weight more slowly than those on the low salt intake. On the low sodium chloride intake, blood pressures were not affected by high dietary sucrose (group 1 versus 2). In contrast, on the high sodium chloride intake, blood pressures were 10-14 mm Hg higher in sucrose-drinking animals than in water-drinking animals (group 3 versus 4). The increments in blood pressures of the high sodium chloride-high sucrose group were not accompanied by greater increments in body weight compared with the animals on the high sodium chloride intake alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Transforming growth factor-beta in neural embryogenesis and neoplasia

The transforming growth factor-beta (TGF-beta) family of polypeptides includes three structurally and functionally related mammalian isoforms that influence cell proliferation, differentiation, and extracellular matrix production. Recent identification of these isoforms in the embryonic murine central nervous system suggests that these factors may regulate proliferation and differentiation of meningeal and neuroepithelial cells during development. Predominant expression of TGF-beta 1 in the leptomeninges compared with the brain of the murine and human central nervous system implicates this isoform in regulation of that mesodermal tissue. Thus, defective TGF-beta regulation may contribute to neoplastic transformation. Failure to activate latent TGF-beta s may contribute to the loss of autocrine regulation seen in meningiomas. Expression of TGF-beta 2 and TGF-beta 3 primarily in embryonic murine radial glia and adult human astrocytes suggests other roles for these isoforms, including glioblast differentiation and guidance of neuroblast migration. Although inhibitory to "normal" astrocyte proliferation, TGF-beta s demonstrate autocrine growth stimulation in vitro among hyperdiploid malignant gliomas, medulloblastomas, primitive neuroectodermal tumors, and anaplastic ependymomas. Hence, synthesis and release of active TGF-beta s by malignant brain tumors may create aberrant stimulatory autocrine loops. The mechanism of TGF-beta-induced growth stimulation is poorly understood. Future studies will likely clarify and identify additional roles for the TGF-beta isoforms in neuro-embryogenesis and neoplasia.

Anesthetic management of the pregnant patient with Marfan syndrome

Two patients with Marfan syndrome who presented for labor and delivery are reviewed. The characteristics of Marfan syndrome and their significance in relation to the physiologic changes due to pregnancy and the implications for anesthetic management are discussed. Marfan syndrome can present with musculoskeletal, cardiovascular, ocular, and pulmonary complications believed to be secondary to an inheritable disorder of connective tissue metabolism. These patients must be carefully evaluated, monitored, and managed during the prepartum and peripartum period. The physiology of pregnancy, particularly the hemodynamic changes, can have catastrophic consequences for the parturient with Marfan syndrome. Serial echocardiographic studies evaluating aortic root size and aortic and mitral valve function are essential during pregnancy. Anesthetic management focuses on minimizing aortic root shear forces and wall stress through invasive monitoring, pharmacologic intervention, and pain treatment.

Quantitative demonstration of spontaneous metastasis by MCF-7 human breast cancer cells cotransfected with fibroblast growth factor 4 and LacZ

We recently established transfectants of MCF-7 human breast cancer cells with fibroblast growth factor 4 (fgf-4) that showed rapid growth and spontaneous metastasis in ovariectomized and tamoxifen-treated nude mice. To establish a spontaneous metastatic model of human breast cancer cells in nude mice with a sensitive marker for detection of micrometastasis, the transfection of fgf-4 was combined with transfection of the bacterial lacZ gene encoding beta-galactosidase. MKL-4 cells, a lacZ transfectant of an fgf-4-transfected cell line, showed the same level of fgf-4 expression as parental cells and expressed a high level of beta-galactosidase activity. When MKL-4 cells were injected s.c. into female nude mice, rapidly growing tumors developed. Whole organ staining for beta-galactosidase activity was able to detect even small numbers of metastatic tumor cells. Micrometastases in lymph nodes, lung, and brain were detected 3 weeks after the tumor cell injections, the first time point tested. Within 12 weeks, metastases were observed in lymph nodes, lung, brain, kidney, perirenal fatty tissues, liver, spleen, retroperitoneum, heart, and gallbladder. The frequency of metastasis and number of foci were correlated with the volume of the primary tumors. The distribution of metastatic sites was similar to that in breast cancer patients. MKL-4 cells may be a useful model for studying the malignant progression of hormone-dependent breast cancer, antimetastatic drugs, or early events in metastasis.

The role of cathepsin D in the invasiveness of human breast cancer cells

The aspartyl protease cathepsin D has been shown to be a marker of poor prognosis when found at high levels in primary breast tumors. It has been suggested that this is because the production of cathepsin D increases the invasive potential of the tumor cells, thus increasing the probability of metastasis. We have therefore conducted experiments to determine if secreted cathepsin D makes a significant contribution to the invasive phenotype of breast cancer cells in the Boyden chamber assay of invasion, which measures the ability of a cell to invade through an artificial basement membrane. Cathepsin D secretion and Boyden chamber invasiveness were measured in nine clones of the breast cancer cell line MCF-7, and no correlation was found between cathepsin secretion and invasive behavior. Invasion assays were also conducted in the presence of the aspartyl protease inhibitor pepstatin A, and no inhibition of the invasive behavior of cells was seen. Since low-pH environments are required for both the activation of pro-cathepsin D and the activity of the mature enzyme, assays were also conducted in the presence of chloroquine to neutralize the pH in the acidic compartments of the cells. This treatment did not inhibit invasiveness. Cathepsin D secretion by the breast cancer cell lines MDA-MB-231, MDA-MB-435, MDA-MB-435s, MDA-MB-468, SK-Br-3, and MCF-7-ADRr was also measured. Again, there was no correlation with invasion. In fact, cathepsin D levels were inversely correlated with aggressive behavior in vivo and in vitro in previously reported studies. These data suggest that cathepsin D secretion by tumor cells is not an important determinant of the invasiveness of the tumor cells per se. These data also reinforce the view that the poor prognosis in clinical breast cancer linked to high tumor levels of cathepsin D is probably due to high levels of cathepsin D in the stromal components of the tumor such as infiltrating inflammatory cells.

Type I IGF receptor and acquired tamoxifen resistance in oestrogen-responsive human breast cancer cells

Tamoxifen inhibited the oestrogen-stimulated proliferation of MCF-7 cells but had little effect on the oestrogen-stimulated proliferation of two tamoxifen-resistant variants (RL-3 and AL-1). The lack of oestrogen antagonist activity in the resistant cells was largely a result of an increased oestrogen agonist activity of tamoxifen on cell proliferation. Proliferation of the tamoxifen-resistant cells was also stimulated by 4-hydroxytamoxifen but not by ICI 164,384, a structurally distinct pure anti-oestrogen. Tamoxifen does not have increased oestrogen agonist activity for the induction of a series of oestrogen-regulated RNAs, and this suggests that the increased agonist activity may be restricted to key components involved in the proliferative response. Tamoxifen-stimulated cell proliferation was dependent on insulin-like growth factor I (IGF-1) in the resistant cells, suggesting that tamoxifen stimulates cell proliferation by sensitising cells to the proliferative effects of IGF-1. This may involve induction of the type-I IGF receptor.

Quantum Dots in Strong Magnetic Fields: Stability Criteria for the Maximum Density Droplet

In this article we discuss the ground state of a parabolically confined quantum dot in the limit of very strong magnetic fields where the electron system is completely spin-polarised and all electrons are in the lowest Landau level. Without electron-electron interactions the ground state is a single Slater determinant corresponding to a droplet centred on the minimum of the confinement potential and occupying the minimum area allowed by the Pauli exclusion principle. Electron-electron interactions favour droplets of larger area. We derive exact criteria for the stability of the maximum density droplet against edge excitations and against the introduction of holes in the interior of the droplet. The possibility of obtaining exact results in the strong magnetic field case is related to important simplifications associated with broken time-reversal symmetry in a strong magnetic field.

Do anti-smoking media campaigns help smokers quit?

As part of an evaluation of the 1990-91 anti-tobacco media campaign carried out by the California Department of Health Services, a study was conducted among 417 regular smokers who had quit during the period of the media campaign. In brief telephone interviews, all respondents identified up to three events or experiences that had influenced them to quit. In response to uncued questions, 6.7 percent of those interviewed indicated that they had been influenced to quit by an advertisement they had seen or heard on radio, television, or billboards. In response to direct questions about the media campaign, 34.3 percent of the respondents indicated that the media campaign's advertisement had played a part in their decision to quit. Applying the 6.7 percentage to the number of Californians who quit smoking in 1990-91, it can be estimated that for 33,000 former smokers, the anti-tobacco media advertisements were an important stimulus in their quit decision. Multiplying the 34.3 percent by the number of former California smokers who quit in 1990-91, the estimate of former smokers for whom the media campaign's advertisements played at least some part in their decision to quit rises to 173,000 persons. While causal attributions from such investigations should be made with caution, the evidence suggests that the 1990-91 campaign did influence substantial number of smokers in California to quit.

The invasive and metastatic properties of hormone-independent but hormone-responsive variants of MCF-7 human breast cancer cells

We have previously isolated a series of MCF-7 human breast cancer cell variants which no longer require estrogen-supplementation for tumor growth in nude mice (Clarke et al. Proc Natl Acad Sci USA 86: 3649-3653, 1989). We now report that these hormone-independent and hormone-responsive variants (MIII, MCF7/LCC1) can invade locally from solid mammary fat pad tumors, and produce primary extensions on the surface of intraperitoneal structures including liver, pancreas, and diaphragm. Both lymphatic and hematogenous dissemination are observed, resulting in the establishing of pulmonary, bone, and renal metastases. The pattern of metastasis by MIII and MCF7/LCC1 cells closely resembles that frequently observed in breast cancer patients, and provides the first evidence of metastasis from MCF-7 cells growing in vivo without supplementary estrogen. The interexperimental incidence of metastases, and the time from cell inoculation to the appearance of metastatic disease are variable. The increased metastatic potential is not associated with an increase in either the level of laminin attachment, laminin receptor mRNA expression, or secreted type IV collagenolytic activity. We also did not detect a significant decrease in the steady-state mRNA levels of the metastasis inhibitor nm23 gene. However, when growing without estrogen in vitro, MCF7/LCC1 cells produce elevated levels of the estrogen-inducible cathepsin D enzyme.

Effect of age on potassium- and tyramine-induced release of norepinephrine from cardiac synaptosomes in male F344 rats

Potassium (K+)-induced norepinephrine (NE) release was examined in preparations of cardiac synaptosomes and sliced atria from 6-, 24-, and 26-mo-old male F344 rats. Cardiac synaptosomes were prepared from rat hearts by collagenase digestion followed by homogenization in 0.32 M sucrose and centrifugation. The synaptosome preparations and the sliced atria were labeled with 3H-NE and then placed in a superfusion system. K(+)-induced net fractional release of NE from synaptosomes prepared from 24- and 26-mo-old rats (4.3% and 3.0%, respectively) was significantly reduced when compared to NE release from synaptosomes from 6-mo-old rats (5.2%). K(+)-induced NE release from sliced atria from 24-mo-old rats (4.7%) was also significantly reduced when compared to NE release from atria from 6-mo-old rats (6.3%). Perfusion of cardiac synaptosomes with buffer prepared without calcium (CA++free, < 5 microM) reduced K(+)-induced release by 50% in all age groups studied. Perfusion with tyramine induced identical rates of NE release from cardiac synaptosomes prepared from 6- and 24-mo-old rats. These results confirm that depolarization-induced NE release from cardiac sympathetic nerves is reduced in the old male F344 rat.

A PrP gene codon 178 base substitution and a 24-bp interstitial deletion in familial Creutzfeldt-Jakob disease

Several mutations in the prion protein (PrP) gene are associated with familial Creutzfeldt-Jakob disease (FCJD). We describe a family in which five members in three generations have had FCJD. The proband and some descendants of the affected members carried an abnormal PrP gene allele. This allele contained a 24-bp deletion from the tandem repeat region of the open reading frame and a codon 178 missense substitution. Observations suggest that the codon 178 mutation is involved in the pathogenesis of FCJD in the family described here. The 24-bp deletion may be an uncommon polymorphism.