G.A and U.U mismatches can stabilize RNA internal loops of three nucleotides

Optical melting experiments on oligoribonucleotides containing internal loops of three nucleotides (two nucleotides opposing one nucleotide) flanked by CG pairs show that the free energy of internal loop formation depends on the sequence of nucleotides within the loop. Internal loops with the potential for A.G and U.U mismatch pairing generally have more favorable free energies of formation than internal loops with potential AA, CC, AC, or UC pairings. In most cases, potential A.G and U.U pairings leaving a single unpaired nucleotide 5' to a flanking CG pair are most stable; those leaving a single nucleotide 3' to a flanking CG pair have intermediate stability. Internal loops of three nucleotides without potential A.G or U.U pairs are the least stable. The results provide an improved model for predicting the folding stabilities of internal loops of three nucleotides.

Cellular localization of glutathione S-transferases in retinas of control and lead-treated rats

PURPOSE

The glutathione S-transferases (GSTs) constitute a family of cytosolic isoenzymes that are involved in the detoxication of electrophilic xenobiotics. The purpose of this investigation was to determine the concentration and cellular distribution of the various classes of cytosolic GSTs in the retina of control and triethyl lead-treated rats and thereby reveal mechanisms by which the cells are protected from damage by lead and other toxicants.

METHODS

The regional and cellular distribution of cytosolic GSTs in rat retina of control and lead-treated animals was studied by immunohistochemistry. Enzyme activity was determined by a spectrophotometric assay. The GST subunit distribution of the entire retina of control and lead-treated animals was determined and quantified by reverse-phase high-performance liquid chromatography (HPLC).

RESULTS

Polyclonal antibodies against mu-class Yb1 and Yb2 GSTs were primarily and strongly reactive with Müller cells and their processes. Anti-Yb1 also reacted with photoreceptor outer segments. Antibodies against two alpha-class GSTs (Ya and Yk) were strongly reactive with Müller cells and their cell processes. Antibodies against Yp and Yc GSTs were reactive with amacrine cells and their processes, and anti-Yp antibodies were reactive against retinal ganglion cells. Treatment of rats with triethyl lead caused diminished reactions of the antibodies against Yb1 and Yp GSTs and increased reactions of anti-Ya with its retinal targets, whereas the total GST activity did not change significantly.

CONCLUSIONS

The positive reaction between the amacrine neuronal cells of retina and the anti-Yp and anti-Yc class antisera broadens the class of neurons that contains GST enzymes protective against toxicant insult. It also has been shown that Müller cells are strongly immuno-positive for Yb1 and Yb2 GST. Because these phagocytic cells are in contact with the vitreous fluid and proximate to pigmented epithelial layer of the eye, these GSTs may protect the cells from toxicants accumulated from this fluid.

Cytochromes CYP1A1 and CYP1B1 in the rat mammary gland: cell-specific expression and regulation by polycyclic aromatic hydrocarbons and hormones

Cultured rat mammary cells express both CYP1A1 and CYP1B1 in response to polycyclic aromatic hydrocarbons (PAH) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in a cell type-specific manner. The expression of each P450 was determined functionally (regioselective PAH metabolism), as apoprotein (immunoblots) and as mRNA (Northern hybridization). The epithelial rat mammary cells (RMEC) expressed CYP1A1, however only after PAH or TCDD treatment. CYP1B1 protein was scarcely detected in these induced RMEC but was surprisingly active as a participant in 7,12-dimethylbenz[a]anthracene (DMBA) metabolism shown through selective antibody inhibition (40% of total activity). CYP1B1 was selectively expressed in the stromal fibroblast population of rat mammary cells to the exclusion of CYP1A1. In the rat mammary fibroblasts (RMF), CYP1B1 protein and associated activity were each present at low levels constitutively and were highly induced by benz[a]anthracene (BA) to a greater extent than by TCDD (12- versus 6-fold). However, BA (10 microM) and TCDD (10 nM) stimulated the 5.2-kb CYP1B1-specific mRNA equally. These increases are consistent with the involvement of the aryl hydrocarbon (Ah) receptor in the transcription of the CYP1B1 gene and with the additional stabilization of CYP1B1 protein by BA, previously observed in embryo fibroblasts. Exactly this regulation of CYP1B1-dependent activity was seen in RMEC suggesting that this arises from exceptionally active CYP1B1 in a small proportion (5%) of residual RMF. The constitutive expression and PAH inducibility of CYP1B1 and CYP1A1 proteins in RMF and RMEC, respectively, were each substantially decreased (approximately 75%) by a hormonal mixture (17 beta-estradiol (0.2 microM) progesterone (1.5 microM) cortisol (1.5 microM) and prolactin (5 micrograms/ml)). Progesterone and cortisol, added singly to RMF suppressed CYP1B1 protein expression (approximately 80%) in both untreated and BA-induced cells, while cortisol also suppressed the 5.2-kb CYP1B1 mRNA. In contrast, 17 beta-estradiol stimulated constitutive expression of CYP1B1 protein (50-75%) and mRNA level (2- to 3-fold), but did not affect CYP1B1 expression in BA-treated RMF. The expression of CYP1A1 and CYP1B1 is therefore highly cell specific even though each is regulated through the Ah receptor. Each P450 exhibits a surprisingly similar pattern of hormonal regulation even though expressed in different cell types.

Alternative nursing environments: do they affect hospital outcomes?

1. A dayroom program focused intensively on functional needs and was implemented for confused geriatric inpatients who otherwise might have been restrained or required sitters. 2. There were fewer complications from hospitalization documented for dayroom patients. 3. There was an increase in family satisfaction regarding the nursing care provided for patients in the alternative environment.

Microglandular hyperplasia of the cervix: a true "pill" lesion?

For many years, it has been assumed that microglandular hyperplasia (MGH) of the cervix occurs almost exclusively in women with endogenous (pregnancy) or exogenous (oral contraceptives) progestational stimulation, but this relationship has never been subjected to rigorous epidemiologic study. All available cases of MGH in our 1990 surgical pathology files were reviewed and clinical histories obtained. For each case of MGH, a control was chosen, consisting of a case in the same time frame of a woman of similar age who had undergone the same procedure (biopsy, conization, hysterectomy) for the same indication. A documented history of current oral contraception or pregnancy within the past 6 months was obtained in 57.9% (22 of 38) of the MGH cases and 47.4% (18 of 38) of the controls. This difference was not statistically significant by McNemar's test for paired data. The histologic features of the MGH lesions (lesion size, cytologic atypia, prominence of inflammation, and presence of solid component and of squamous metaplasia) were evaluated blindly without knowledge of the hormonal history. There were no statistically significant differences by the chi 2 test of association between cases with and without hormonal histories. This study provides no support for considering MGH or any of its constituent features. This study provides no support for considering MGH or any of its constituent features as causally related to oral contraception or other known hormonal perturbations.

Post-irradiation soft tissue sarcoma

From 1975 to 1993, 11 of 375 patients treated for soft tissue sarcoma presented with post-irradiation sarcoma. The mean time interval between irradiation therapy and onset of the second neoplasm was 15.8 years (4-31 years). The total radiation dosage ranged from 12 to 60 Gy with a mean of 40 Gy. All patients had complete staging including CT or MRI of the tumour site, and CT of the lung. Surgical resection was the treatment of choice. Wide margins could be achieved in 10 patients. One had a marginal resection. Tumours included malignant fibrous histiocytoma, haemangiosarcoma, rhabdomyosarcoma, malignant schwannoma, fibrosarcoma and undifferentiated sarcoma. All patients were reassessed in our outpatient clinic. After a mean follow-up of 4.7 years (1.0-11.5 years), only 1 patient had died because of the tumour. Although post-irradiation sarcomas are rather infrequently observed, these tumours must be suspected when alterations or symptoms occur in a previously irradiated region. Early detection provides the chance of curative, wide margin resection.

Binding of TFIID and MEF2 to the TATA element activates transcription of the Xenopus MyoDa promoter

Members of the MyoD family of helix-loop-helix proteins control expression of the muscle phenotype by regulating the activity of subordinate genes. To investigate processes that control the expression of myogenic factors and regulate the establishment and maintenance of the skeletal muscle phenotype, we have analyzed sequences necessary for transcription of the maternally expressed Xenopus MyoD (XMyoD) gene. A 3.5-kb DNA fragment containing the XMyoDa promoter was expressed in a somite-specific manner in injected frog embryos. The XMyoDa promoter was active in oocytes and cultured muscle cells but not in fibroblasts or nonmuscle cell lines. A 58-bp fragment containing the transcription initiation site, a GC-rich region, and overlapping binding sites for the general transcription factor TFIID and the muscle-specific factor MEF2 was sufficient for muscle-specific transcription. Transcription of the minimal XMyoDa promoter in nonmuscle cells was activated by expression of Xenopus MEF2 (XMEF2) and required binding of both MEF2 and TFIID to the TATA motif. These results demonstrate that the XMyoDa TATA motif is a target for a cell-type-specific regulatory factor and suggests that MEF2 stabilizes and amplifies XMyoDa transcription in mesodermal cells committed to the muscle phenotype.

Health of the public. The academic response. Health of the Public Mission Statement Working Group

Aging of the population, increasing prevalence of chronic and disabling illnesses with multiple social and behavioral risk factors, concern about quality of care, and escalating costs of medical care require fundamental changes in the way that academic health centers discharge their mission. This article describes a newly developed "Mission Statement" for academic health centers that wish to contribute positively to the health of the populations that they serve. A shift toward addressing the needs of the public may produce increasing institutional strength, long-run stability, and enhanced productivity, as well as higher quality, more cost-effective care for patients. Seventeen centers in the Health of the Public Program are currently conducting activities that implement the described mission elements. The goals and objectives described herein create a foundation for change, with more balanced institutional goals, and could turn an emerging confrontation between academe and its public into an opportunity for both.

The conserved carboxy-terminal domain of Saccharomyces cerevisiae TFIID is sufficient to support normal cell growth

We have examined the structure-function relationships of TFIID through in vivo complementation tests. A yeast strain was constructed which lacked the chromosomal copy of SPT15, the gene encoding TFIID, and was therefore dependent on a functional plasmid-borne wild-type copy of this gene for viability. By using the plasmid shuffle technique, the plasmid-borne wild-type TFIID gene was replaced with a family of plasmids containing a series of systematically mutated TFIID genes. These various forms of TFIID were expressed from three different promoter contexts of different strengths, and the ability of each mutant form of TFIID to complement our chromosomal TFIID null allele was assessed. We found that the first 61 amino acid residues of TFIID are totally dispensable for vegetative cell growth, since yeast strains containing this deleted form of TFIID grow at wild-type rates. Amino-terminally deleted TFIID was further shown to be able to function normally in vivo by virtue of its ability both to promote accurate transcription initiation from a large number of different genes and to interact efficiently with the Gal4 protein to activate transcription of GAL1 with essentially wild-type kinetics. Any deletion removing sequences from within the conserved carboxy-terminal region of S. cerevisiae TFIID was lethal. Further, the exact sequence of the conserved carboxy-terminal portion of the molecule is critical for function, since of several heterologous TFIID homologs tested, only the highly related Schizosaccharomyces pombe gene could complement our S. cerevisiae TFIID null mutant. Taken together, these data indicate that all important functional domains of TFIID appear to lie in its carboxy-terminal 179 amino acid residues. The significance of these findings regarding TFIID function are discussed.

Platelet-activating factor induces intestinal necrosis, but not septic shock, in germ-free and specific-pathogen-free rodents

Platelet-activating factor (PAF) was injected into conventional mice, endotoxin-resistant mice (C3H/HEJ), conventional rats, germ-free rats and specific-pathogen-free (SPF) mice. The PAF resulted in significant necrosis and damage to the small intestines of all the animals tested. In general, the frequency and severity of the lesions were similar in all groups. All the conventional rats and mice, as well as the endotoxin-resistant HEJ mice, were dead 18 h after the injection of the PAF, while all the germ-free rats and the SPF mice survived. These data demonstrate that development of massive intestinal lesions, in the absence of aerobic bacteria, is not sufficient to cause the death of the host from septic shock and endotoxaemia.

31P NMR spectra of an oligodeoxyribonucleotide duplex lac operator-repressor headpiece complex

The interaction of a symmetric lac operator duplex, d(TGTGAGCGCTCACA)2, with the N-terminal 56-residue headpiece fragment of the lac repressor protein was monitored by 31P NMR spectroscopy. The changes in the 31P chemical shifts upon addition of the headpiece demonstrated an end point of two headpiece fragments per symmetric 14-mer duplex with each headpiece binding to the T1pG2pT3pG4pA5 ends of the duplex. The specific phosphate 31P perturbations observed are consistent with those residues implicated in protein binding by previous NMR, molecular biological, and biochemical techniques. Upon complexation, the 31P signals of phosphates G2-A5 showed upfield or downfield shifts (less than 0.2 ppm) while most other residues were unperturbed. The interactions were dependent on ionic strength. The 31P NMR data provide direct evidence for predominant recognition of the 5' strand of the 5'-TGTGA/3'-ACACT binding site.

Cloning of the Schizosaccharomyces pombe TFIID gene reveals a strong conservation of functional domains present in Saccharomyces cerevisiae TFIID

The gene encoding the Schizosaccharomyces pombe TATA box-binding factor (TFIID) was cloned and sequenced. The gene contains three introns and codes for a polypeptide of 231 amino acids. The cDNA-expressed protein showed both TATA box-binding and basal transcription activities. The carboxy-terminal three-quarters of S. pombe TFIID shares an extraordinary degree of amino acid sequence homology with a corresponding region of Saccharomyces cerevisiae TFIID that has been shown to be necessary and sufficient for TATA box-binding and basal transcription activities. In contrast, the amino-terminal regions of the S. pombe and S. cerevisiae TFIIDs differ markedly in amino acid sequence and composition. Structure and function relationships of TFIID are discussed in light of these data.

Bedside chest radiography: diagnostic efficacy

In order to evaluate the efficacy of bedside chest radiography, a prospective study was completed of 140 patients admitted to the surgical and medical intensive care units over a two-month period. A total of 1132 consecutive bedside radiographs was analyzed for malposition of tubes and lines and interval changes in the cardiopulmonary findings. The median number of bedside radiographs per patient was 0.7 per day. Endotracheal or tracheostomy tubes were present in 54% of all examinations; among these 12% were malpositioned. Central venous catheters were present in 47%; among these 9% were malpositioned. Interval changes regarding cardiopulmonary findings (pneumothorax, collapse, diffuse or focal infiltrate, effusion, and congestive heart failure) were present in 44% of the radiographs after the admission one. Overall there were new findings or changes affecting the patient's management present in 65% of the radiographs. The use of bedside radiography appeared to be appropriate.

Imaging of lymphoid structures with indium-111-labeled lymphocytes

The ability of indium-111 (111In)-oxine-labeled syngeneic lymphocytes to migrate normally and their suitability for imaging both normal lymphoid structures and those with metastatic disease were assessed. Sixty-two ACI rats were studied, 34 of which received injections in the left foot pad with 1 X 10(6) syngeneic H-4-II-E hepatoma cells nine to 44 days before imaging. Most animals were bearing palpable tumors when imaged. In 53 experiments, 1-6 X 10(8) 111In-oxine-labeled lymphocytes with a labeling concentration of 5-80 microCi/10(8) cells were injected intravenously. Gamma camera images were obtained 22 hours later. After the last image, the animals were killed. The lymph nodes, liver, spleen, lungs, and left femur were dissected, and the recovered radioactivity was determined in a gamma well counter. Lymph nodes could be partially or completely visualized in 70% of the animals (15 tumor-bearing and 16 normal out of 44 technically satisfactory experiments). Large metastatic nodes were seen clearly. Lymphocytes labeled with 111In-oxine exhibited a normal migration from blood to lymph nodes.

Bracing and supporting of the lumbar spine

The orthopaedic surgeon should be familiar with various supports and braces for the treatment of low back pain. Severe cases of spinal instability always need a Hohmann overbridging brace, whereas the milder form of motion-segment instability is treated with one of the elastic supports. In cases of osteoporosis of the spine and insufficiency of the lumbosacral junction the Lindemann 2/3 semi-elastic brace is prescribed.

Effects of low to moderate lead exposure on slow cortical potentials in young children: two year follow-up study

A follow-up study of slow cortical potentials in children with elevated blood lead (PbB) histories was conducted two years after initial evaluation. An age x PbB interaction was again observed wherein slow wave (SW) voltage varied as a linear function of PbB with the slope of the function dependent on age. The linear relationship of SW voltage and PbB was significant using either original PbB values, (14-55 micrograms/dl), follow-up values (11-39 micrograms/dl), or the mean of the two PbB values. No evidence of a threshold for this effect was observed. The similarity of results obtained at initial and follow-up assessments suggests that the observed alterations in CNS function are persistent, despite a significant decrease in mean PbB across time. The observed change in SW voltage at PbB levels previously considered to be harmless suggests the need to reconsider the currently accepted 30 micrograms/dl threshold for undue lead absorption in children.

[Quantitative evaluation, indications and value of computer tomography of the lumbar spine]

Beside demonstrating morphological changes, CT enables one to make quantitative measurements of the spinal canal (sagittal diameter, transverse diameter, area of the spinal canal, width of the lateral recess and symmetry of the articular joints). A reduction of the transverse diameter of the spinal canal or asymmetry of the articular joints is associated with an increased and earlier incidence of back pain. In addition, patients with asymmetrical vertebral joints showed more frequent and earlier development of disc prolapse.

[Stenosis of the lumber spine. Clinical picture, diagnosis, treatment (author's transl)]

Disc herniation is the most common reason for sciatica followed by osseous entrapment syndromes of the cauda equina. The osseous entrapment of nervous structures is possible within 3 segments of the spinal canal, the center, the recess and the intervertebral foramen. In all cases there is a disproportion of the size of the nervous structures and osseous gliding space. Central lumbar spinal stenosis is associated in 70% with limping (neurogenic claudication) which is often misinterpreted as vascular claudication. Clinic, diagnosis, therapy of lumbar spinal stenosis is described.

[CT image of a free fat graft (FFG) within hemilaminectomy space (author's transl)]

To prevent scarformation after hemilaminectomy many authors (1, 2, 6, 8) use free autologous fat grafts. CT scanning reveals vitality or death if the transplant. CT enables to control intra vitam whether FFG diminishes postnucleotomy syndrome caused by scar formation.