Light microscopic radioautographic study on DNA synthesis in aging mice corneas

The morphological change and DNA synthesis of the aging mice corneal cells were investigated by light microscopic radioautography after injection of tritiated thymidine. The result showed that the incorporation of tritiated thymidine in corneal cells changed with aging. The sites of tritiated thymidine incorporation were located in the epithelium from postnatal day 19 to 1 year after birth, in the stroma and endothelium from prenatal day 19 to postnatal day 8 only. The labeling index in the epithelial cells reached its highest value at 1 month after birth. Labelled stromal and endothelial cells reached their peaks simultaneously on the third day after birth and disappeared completely from postnatal 1 month onwards. The thickness of the cornea increased obviously at one month and there were no notable morphological change thereafter. Our investigation provides for the first time a systematic study on the age-related changes of DNA synthesis and construction in the aging mice corneas.

Hel-N1: an autoimmune RNA-binding protein with specificity for 3' uridylate-rich untranslated regions of growth factor mRNAs

We have investigated the RNA binding specificity of Hel-N1, a human neuron-specific RNA-binding protein, which contains three RNA recognition motifs. Hel-N1 is a human homolog of Drosophila melanogaster elav, which plays a vital role in the development of neurons. A random RNA selection procedure revealed that Hel-N1 prefers to bind RNAs containing short stretches of uridylates similar to those found in the 3' untranslated regions (3' UTRs) of oncoprotein and cytokine mRNAs such as c-myc, c-fos, and granulocyte macrophage colony-stimulating factor. Direct binding studies demonstrated that Hel-N1 bound and formed multimers with c-myc 3' UTR mRNA and required, as a minimum, a specific 29-nucleotide stretch containing AUUUG, AUUUA, and GUUUUU. Deletion analysis demonstrated that a fragment of Hel-N1 containing 87 amino acids, encompassing the third RNA recognition motif, forms an RNA binding domain for the c-myc 3' UTR. In addition, Hel-N1 was shown to be reactive with autoantibodies from patients with paraneoplastic encephalomyelitis both before and after binding to c-myc mRNA.

Enhancement in the safety of immune globulins prepared from high-risk plasma

Hyperimmune gamma-globulins have proven efficacious in the prevention and treatment of viral infections, including those caused by hepatitis A and B viruses, cytomegalovirus, parvovirus. Interest in the prevention and/or treatment of infections caused by human immunodeficiency virus (HIV) has led to clinical trials with anti-HIV immune plasma and purified immune globulin prepared from donors who are actively infected with HIV. The handling and fractionation of this or other infectious plasma requires the construction and operation of virus containment facilities designed to protect fractionation employees and the immediate environment. This requirement would be reduced substantially by applying virucidal procedures prior to or during plasma pooling. We have shown that heating plasma at 56 degrees C for 1 h followed by treatment with 1% tri(n-butyl) phosphate (TNBP) and 1% Triton X-100 for 4 h at 30 degrees C resulted in the inactivation of > or = 10(12.1) tissue culture infectious doses (TCID50) of HIV. With this treatment, the recovery of IgG was 87 +/- 3%. Fractionation of treated plasma by cold ethanol precipitation proceeded normally, and overall recovery, purity, and potency against selected viral markers were unaffected. The additional treatment of plasma with 15 g/l Aerosil for 4 h at 45 degrees C removed 10(4.5) TCID50 of HIV but resulted in substantial IgG losses both prior to and following fractionation. We conclude that potentially infectious plasma can be treated at 56 degrees C for 1 h and by TNBP/Triton X-100 at 30 degrees C for 4 h prior to fractionation. These steps appear sufficient to assure safety and to permit routine fractionation of plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Postnatal development and aging of esophageal epithelium in mouse: a light and electron microscopic radioautographic study

DNA synthesis and fine structure of the esophageal epithelium of ddY mouse in different age groups, from neonatal to senescent, were investigated by light and electron microscopic radioautography after 3H-thymidine labeling in vitro. At 1-3 days after birth, the esophagus was lined with two cell types, ciliated and nonciliated cells. From 1 week on, ciliated cells could not be found. At 2 weeks, the superficial cells still possessed nuclei and short microvilli on the apical plasma membranes. From 1 month, the superficial cells became keratinized and the microvilli on the apical plasma membrane disappeared. With aging of the mice, the epithelia became markedly thick. These results show that disappearance of ciliated cells, keratinization of superficial cells and increase of the thickness are the main changes in structure of mouse esophageal epithelium from neonatal to senescent ages. By light microscopic radioautography, labelled cells were almost confined in the basal layer, regardless of the aging stages. The highest labeling index was recorded at 1 day after birth, then decreased with age. By electron microscopic radioautography, silver grains indicating DNA synthesis were observed in nuclei. As compared with those of unlabelled cells in the basal layer, the nuclei and nucleoli of labelled cells were larger, with fewer cell organelles. The present study provides, for the first time, the basic quantitative data regarding cell proliferation of mouse esophageal epithelium from neonatal to senescent stage.

Temporal lobe atrophy on magnetic resonance imaging in the diagnosis of early Alzheimer's disease

OBJECTIVE

To evaluate the use of simple ratings and linear measures of atrophy in the temporal lobe structures obtained with magnetic resonance imaging coronal scans in the diagnosis of early Alzheimer's disease.

DESIGN

Prospective series. The National Institute for Neurological Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease. Blinded assessment.

SETTING

Dementia study in a university hospital.

SUBJECTS

Patients with Alzheimer's disease (n = 34), scoring 150 or more on the Extended Scale for Dementia, and age-matched healthy community volunteers (n = 39) who had both magnetic resonance imaging coronal scans and a psychometric assessment using the Extended Scale for Dementia within 6 months were included.

MEASURES

MAIN MEASURES

T1-weighted magnetic resonance imaging coronal scans, a 1.5-T system. The degree of atrophy rated (0 to 4) in both sides of the temporal neocortex, entorhinal cortex, hippocampal formation, temporal horns, third ventricle, lateral ventricles, and frontal and parietal cortex. Linear measures: the area of hippocampus and the maximal transverse width of temporal horns.

RESULTS

Differentiation between patients with Alzheimer's disease and controls was limited by considerable variations in sensitivity and specificity. Receiver operating characteristics analysis revealed a clear order of discrimination, the entorhinal cortex and the temporal neocortex being the two best, followed by the temporal horns and hippocampal formation. For a given specificity of 90%, the corresponding sensitivity for the entorhinal cortex, temporal neocortex, temporal horns, and hippocampal formation was 95%, 63%, 56%, and 41%, respectively. Linear measures differed significantly but showed considerable overlap.

CONCLUSION

The presence of rated atrophy in selected temporal structures makes the diagnosis of Alzheimer's disease more likely, but the absence does not rule out the possibility of early Alzheimer's disease.

[Study on casting precision of plat castable ceramic crowns]

The plat castable ceramic crown was made with investment material prepared in our college with our own casting technique by a Chinese-made casting machine. The accuracy and fitness of the crown were studied and appraised. Results show that the margin of fitness is 46 microns and that the cement film thickness of the dies in the spacer material group is 65.13 microns. Hence the results are satisfactory. The Plat castable ceramic crown might be used in clinical dentistry.

Human infection by genetically diverse SIVSM-related HIV-2 in west Africa

Our understanding of the biology and origins of human immunodeficiency virus type 2 (HIV-2) derives from studies of cultured isolates from urban populations experiencing epidemic infection and disease. To test the hypothesis that such isolates might represent only a subset of a larger, genetically more diverse group of viruses, we used nested polymerase chain reactions to characterize HIV-2 sequences in uncultured mononuclear blood cells of two healthy Liberian agricultural workers, from whom virus isolation was repeatedly unsuccessful, and from a culture-positive symptomatic urban dweller. Analysis of pol, env and long terminal repeat regions revealed the presence of three highly divergent HIV-2 strains, one of which (from one of the healthy subjects) was significantly more closely related to simian immunodeficiency viruses infecting sooty mangabeys and rhesus macaques (SIVSM/SIVMAC) than to any virus of human derivation. This subject also harboured multiply defective viral genotypes that resulted from hypermutation of G to A bases. Our results indicate that HIV-2, SIVSM and SIVMAC comprise a single, highly diverse group of lentiviruses which cannot be separated into distinct phylogenetic lineages according to species of origin.

Light microscopic radioautographic study on the DNA synthesis of prenatal and postnatal aging mouse retina after labelled thymidine injection

The DNA synthesis of mouse retina from the 19th prenatal day through 12 months postnatal has been studied by light microscopic radioautography after the injection of tritiated thymidine. A peak of the labeling index after incorporation of tritiated thymidine was found at fetal day 19. The labelled cells decreased gradually with the developing of the eye from the first postnatal day and were completely disappeared in two weeks after birth. The data also indicated obvious regional differences of the incorporation of tritiated thymidine during the periods of the retina development. The labeling index was the greatest in the anterior region compared to the equator region and the posterior region in the same group of age. The average number of the silver grains in labelled nucleus lead to a decrease with the development of the retina after birth, but there was no significant regional differences found in the same group of age. The data shown from this study suggest that the cell differentiation in mouse retina proceed from posterior to anterior region.

Cytoplasmic domain truncation enhances fusion activity by the exterior glycoprotein complex of human immunodeficiency virus type 2 in selected cell types

To investigate the glycoprotein determinants of viral cytopathology, we constructed chimeric env genes between a noncytopathic strain of human immunodeficiency virus type 2 (HIV-2), designated HIV-2/ST, and a highly fusogenic and cytopathic variant derived from this virus. Expression of the resulting chimeric glycoproteins indicated that efficient syncytium formation in the human T-cell line Sup T1 mapped to the C-terminal region of the transmembrane (TM) glycoprotein subunit. In this region, the wild-type and cytopathic ST glycoproteins differed by only four amino acids and by the presence of a premature termination codon in the cytopathic variant. Subsequent site-directed mutagenesis indicated that the cytoplasmic domain truncation was responsible for the enhanced fusion activity. This modification, however, increased the fusion activity of the glycoprotein only in Sup T1 cells (in which the ST variant arose) but not in Molt 4 clone 8 or peripheral blood mononuclear cells. These observations indicate that the length of the cytoplasmic domain of the HIV-2 glycoprotein modulates the fusion activity of the exterior glycoprotein complex in a cell-specific manner. Such adaptability appears to permit the emergence of fusogenic variants during HIV-2 passage in vitro and may also regulate viral growth or cytopathic effects in selected cell types during natural infection in vivo.

Model adducts of benzo[a]pyrene and nucleosides formed from its radical cation and diol epoxide

Reference adducts formed by reaction of deoxyribonucleosides with the ultimate carcinogenic forms of benzo[a]pyrene (BP), BP radical cation and BP diol epoxide, are essential for identifying the structures of adducts formed in biological systems. Electrochemical oxidation of BP in the presence of dG or dA produces adducts from BP radical cation. When 8 equiv of charge are consumed, four adducts are formed with dG: 7-(BP-6-yl)Gua, 8-(BP-6-yl)Gua, N2-(BP-6-yl)dG and 3-(BP-6-yl)dG. With 2 equiv of charge, however, only 7-(BP-6-yl)Gua and 8-(BP-6-yl)dG (BP-6-C8dG) are formed. Anodic oxidation of BP-6-C8dG affords 8-(BP-6-yl)Gua. Anodic oxidation of BP in the presence of dA produces 7-(BP-6-yl)Ade. Reaction of BP diol epoxide with dG yields 10-(guanin-7-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydroBP, whereas reaction with dA affords three adducts, 10-(adenin-7-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydroBP and two isomers of 10-(deoxyadenosin-N6-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydroBP . On the basis of comparative kinetic studies among adducts of aromatic hydrocarbons and dG or G, only BP-6-C8dG easily loses the sugar moiety, providing a basis for a mechanism of hydrolysis of the glycosidic bond.

Effect of sub-anaesthetic infusions of propofol on peak velocity of saccadic eye movements

Peak velocity of saccadic eye movements was studied in six healthy volunteers who received either 0.9% sodium chloride (as a control) or a stepwise rising propofol infusion regime of 0.24, 0.6 and 1.5 mg kg-1 h-1, which produced arterialized venous concentrations equivalent to 1%, 6% and 13% of the estimated EC50 for propofol. The infusion lasted for 75 min (25 min at each infusion rate) and was followed by a 2-h post-infusion recovery period. Peak saccadic velocity was highly significantly depressed during the 15-25-min period after the start of the second and third propofol infusions compared with saline. The relationship between arterialized venous blood concentration and peak saccadic velocity was similar during recovery when concentrations were falling to that during increasing blood propofol concentrations. Peak saccadic velocity decreased linearly with increasing log10 propofol concentration in the range of 25-800 ng ml-1 (14% of control per decade). Measured arterialized venous-blood propofol concentrations were variable, and systematically greater than computer predictions at the two higher infusion rates. In only half the subjects were the subjective assessments significantly correlated with log10 propofol concentrations or with percentage reduction in peak saccadic velocity.

Structure of the flavone hymenoxin

2-(3,4-Dimethoxyphenyl)-5,7-dihydroxy-6,8-dimethoxy-4H-chromen-4-o ne, C19H18O8, Mr = 374.38, monoclinic, P2(1)/n, a = 9.026(4), b = 15.054(6), c = 12.829(6) A, beta = 100.98(4) degrees, V = 1711(1) A3, Z = 4, Dx = 1.450 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.07 cm-1, F(000) = 784, T = 295 K, R = 0.0778 for 2280 independent reflections. The nearly planar AB ring system (0.04 A r.m.s.d.), O(1) to C(10), and the planar C ring (0.001 A r.m.s.d.) are almost coplanar with an interplanar angle of only 4.4(4) degrees. The methyl groups at C(6) and C(8) are rotated out of the molecular plane on opposite sides with torsion angles C(5)C(6)O(6)C(11) = -94.5(4) and C(7)C(8)O(8)C(12) = 109.0(4) degrees. The methyl groups of ring C are coplanar with the ring, C(3')C(4')O(4')"(13) = 0.2(5) and C(6')C(5')O(5')C(14) = 1.3(5) degrees. The carbonyl group forms an intramolecular hydrogen bond with O(5), O(5)...O(4) = 2.612(5), H(5O)...O(4) = 1.85(4) A, O(5)-H(5O)...O(4) = 151.9(8) degrees, and an intermolecular hydrogen bond with O(7) of an adjacent molecule, O(7)...O(4) (-0.5 + x, -0.5 - y, 0.5 + z) = 2.689(5), H(7O)...O(4) = 1.92(4) A, and O(7)-H(7O)...O(4) = 163.2(8) degrees.

Effect of low concentrations of nitrous oxide and isoflurane on peak velocity of saccadic eye movements

Peak velocity of saccadic eye movements was studied in six healthy volunteers who were each given, on separate days, 5% and 10% MAC of nitrous oxide (5% and 10% end-tidal) or of isoflurane (0.06% and 0.12% end-tidal) or air, each gas for 25 min. Subjective assessment following each treatment was also undertaken. No significant difference was found between air and either 5% or 10% nitrous oxide. However, significant differences occurred at 15 and 25 min after 0.06% isoflurane compared with air (P less than 0.05) and highly significant differences were present 5, 15 and 25 min after 0.12% isoflurane when compared with air and nitrous oxide (P less than 0.01). In contrast, there was little difference between the three gases by subjective assessment.

Efficient Multistep Photoinitiated Electron Transfer in a Molecular Pentad

A synthetic five-part molecular device has been prepared that uses a multistep electron transfer strategy similar to that of photosynthetic organisms to capture light energy and convert it to chemical potential in the form of long-lived charge separation. It consists of two covalently linked porphyrin moieties, one containing a zinc ion (P(Zn)) and the other present as the free base (P). The metailated porphyrin bears a carotenoid polyene (C) and the other a diquinone species (Q(A)-Q(B)). Excitation of the free-base porphyrin in a chloroform solution of the pentad yields an initial charge-separated state, C-P(Zn)-P(.+).-Q(A)(-)-Q(B), with a quantum yield of 0.85. Subsequent electron transfer steps lead to a final charge-separated state, C(.+)-P(Zn)-P-Q(A)-Q(B)(.-), which is formed with an overall quantum yield of 0.83 and has a lifetime of 55 microseconds. Irradiation of the free-base form of the pentad, C-P-P-Q(A)-Q(B), gives a similar charge-separated state with a lower quantum yield (0.15 in dichloromethane), although the lifetime is increased to approximately 340 microseconds. The artificial photosynthetic system preserves a significant fraction ( approximately 1.0 electron volt) of the initial excitation energy (1.9 electron volts) in the long-lived, charge-separated state.

[Clinical classification of altitude sickness: analysis of 13,403 cases]

The clinical classification and characteristics of various types of plateau sickness were reported after analysing 13,403 such cases in Tibet region. The conception of plateau sickness and the opinion of its classification in China and abroad were discussed and the names suggested for various types of the disease were also given. However, the rationality of different classifications of the sickness was questioned according to the present understanding of its pathology and clinical manifestations. It is the opinion of the authors to divide this sickness, first of all, into two categories of acute and chronic and then to subdivide each of them into several types according to clinical symptoms and the pathological changes of principally encroached organs. The acute category was subdivided into 4 types as follows: 1. high altitude acute response (HAAR); 2. high altitude pulmonary edema (HAPE); 3. high altitude cerebral edema (HACE); 4. high altitude children cardiopathy (HACC). The chronic category was subdivided into 5 types as follows: 1. high altitude chronic response (HACR); 2. high altitude erythoblastosis (HAEb); 3. high altitude adult cardiopathy (HAAC); 4. high altitude hypertension (HAHyper); 5. high altitude hypotension (HAHypo). This classification is useful in clinical practice and research.

A LINE 1 sequence interrupts the rat alpha 2u globulin gene

The rat alpha 2u globulin gene family is composed of about 25 members with closely related structure. Several of these genes are transcriptionally active in the liver of adult males. We isolated about 50 independent genomic clones from the library and determined complete nucleotide sequences of two. Although they were alike and revealed structural features prerequisite for active genes, one cloned gene was interrupted in the 6th intron with about 900 bp 5' truncated and 3'-terminal triplicated form of LINE 1 sequence flanked by 16 bp complete direct repeat originating from the 6th intron. Within the inserted LINE 1 an excellent splicing acceptor homologue with a precedent lariat junction motif and multiple polyadenylation signals was identified. Thus, the possible production of a chimeric RNA, the last exon of which would be replaced by a part of LINE 1, has to be considered.

Bond strength of Panavia EX to dental amalgam

The tensile bond strengths of Comspan (a conventional resin used with composite-bonded prostheses) and Panavia EX (a newer adhesive bonding material) to different types of amalgam were determined. The results were compared with the tensile bond strengths of these resins to etched bovine enamel and properly prepared Rexillium III. The results showed that all of the resin-amalgam bond strengths were statistically less than those of bonding resin to etched bovine enamel or Rexillium III. Coverage of existing amalgam restorations by the metal framework with etched-metal resin-bonded retainers is contraindicated when using either the conventional bonding agent or the new adhesive bonding material, Panavia EX.

Length heterogeneity in rat salivary gland alpha 2 mu globulin mRNAs: multiple splice-acceptors and polyadenylation sites

Rat alpha 2 mu globulins are coded for by a family of about 25 structurally related genes, some of which are expressed in the male adult liver while the other subset seems to be active in several excretory organs, including salivary and lacrymal glands. To estimate the number and specificity of genes expressed in the salivary glands, we determined nucleotide sequences of 30 cDNA clones. At least two alpha 2 mu globulin genes are active and two thirds of mRNAs were shown to code for the peptide two amino acids shorter than the others. Unexpected observation was the intense length polymorphism in the 3' non-coding 6th intron-7th exon regions presumably caused by alternative splice-acceptor selection. At least six acceptor sites were utilized and the longest type retained the entire 6th intronic sequence resulting in a formation of unusually longer product. A stable mRNA molecule of this type was demonstrated in salivary glands by Northern blotting probed with the 6th intron-specific fragment. Together with three independent polyadenylation sites, the rat salivary glands generate a diverse set of alpha 2 mu globulin mRNAs.

[Multifactorial analysis of survival in breast cancer]

Eleven clinical and pathological factors were eligible for study in relation to the survival of 617 female patients with breast cancer treated by radical mastectomy. All the patients have been followed for more than five years. The data were analyzed by the Cox's proportional hazards regression model. A final set of five independent significant prognostic factors was obtained. In order of importance, they were clinical stage, age at diagnosis, axillary lymph node status, histologic type and size of the primary. To test the time-dependency of these factors using Cox's model, all except age reduced their prognostic impact significantly after five years, however, age was a powerful prognostic factor for long-term survival. A prognostic index based on the regression coefficients was constructed. This index can give a better prediction for our patients' survival and be taken as reference when formulating treatment protocols for breast cancer.