Molecular cloning of M6: identification of a PLP/DM20 gene family

M6 is a membrane glycoprotein that is expressed on central neurons and certain polarized epithelia from early developmental stage. Antibodies against M6 interfere with cerebellar neurite outgrowth in vitro. Two closely related cDNAs were obtained by expression cloning, both of which showed high homology with the major CNS myelin protein PLP/DM20. Although M6 and PLP/DM20 share many molecular characteristics, in situ hybridization revealed nonoverlapping distributions of their mRNAs in mouse CNS. The identification of a gene family including neuron-specific M6 and glia-specific PLP/DM20 in CNS suggests a broader functional role for these molecules than myelination.

Free energies for refolding of the common beta turn into the inverse-common beta turn: simulation of the role of D/L chirality

Quantitative estimates of the Gibbs free-energy change (delta G) for refolding of one beta-turn conformation into another would assist rational protein design. For beta-turn models, we studied a chirally representative set of nine peptides of the form CH3CO-L1-L2-NHCH3, where loop residues L1 (i + 1) and L2 (i + 2) are achiral Gly (G), L-Ala (A), or D-Ala (a). The stabilities of their common (type I) and inverse-common (type I') beta-turn conformers (GGI is the type-I GG conformer, etc.) were estimated by free-energy simulations using explicit water molecules. An alpha-hydrogen atom of a Gly residue at L1 or L2 was replaced by a methyl group by slow growth. The resulting conformers were less stable than GGI and GGI' by about 1-3 kcal/mol (delta G = 0.9 kcal/mol for AGI and aGI', 1.0 kcal/mol for GAI and GaI', 2.1 kcal/mol for aGI and AGI', and 2.8 kcal/mol for GaI and GAI'; 1 kcal = 4.18 kJ). The delta G value for simultaneous growth of one methyl group at L1 and another at L2 was the sum of the two component delta G values. The delta G values for I-->I' refolding of the common beta-turn conformer into the inverse-common beta-turn conformer ranged over 6 kcal/mol (-3.0 for aa, -1.8 for Ga, -1.1 for aG, -0.7 for Aa, 0 for GG, 0.7 for aA, 1.1 for AG, 1.8 for GA, and 3.0 for AA). Thus, replacing L-Ala by D-Ala at both L1 and L2 of a common beta turn may contribute as much as 6 kcal/mol toward its refolding as an inverse-common beta turn.

[Effects of "he xiang zhuang gongfu" on respiratory function in healthy adults]

Eleven healthy adults who practised He Xiang Zhuang Gongfu (HGF) were followed for 6 months; 15 pulmonary function tests were determined before HGF practice, 2 months and 6 months after HGF practice. All 11 subjects took the HGF exercise every day for 30 minutes. Samplings were taken before subjects had ever practised HGF as control value, immediately and 30 minutes after HGF exercise. In the 2nd month and 6th month of HGF practice. The results indicated that VO2 decreased after 2 and 6 months HGF practice, and the effect even persisted to 30 minutes after HGF exercise, indicating that HGF may reduce metabolic rate and decrease the oxygen consumption of body. The possible mechanism was discussed. MVV had an up tendency after HGF practice, which suggested the possibility of strengthening respiratory muscle by HGF. HGF may be a good physical exercise and can induce a wakeful hypometabolic physiologic state.

Differentiation of Rickettsia japonica by restriction endonuclease fragment length polymorphism using products of polymerase chain reaction amplification with Rickettsia rickettsii 190-kilodalton surface antigen gene primers

Restriction fragment length polymorphism of polymerase chain reaction (PCR) amplification products differentiated Rickettsia japonica, a causative agent of Oriental spotted fever, from other spotted fever group (SFG) rickettsiae. Primer pair Rr190. 70p and Rr190. 602n of R. rickettsii 190-kDa antigen gene sequence primed genomic DNAs obtained from R. japonica, type strain YH and strains NT, NK, YKI, and TKN. The products were cleaved by PstI but not by AfaI restriction endonuclease. The PstI digestion pattern of PCR-products amplified from all strains of R. japonica was identical and easily differentiated from that of other SFG rickettsiae. The present study demonstrated a genotypic difference between R. japonica and other pathogenic SFG rickettsiae.

[The effect of 764-3 on alveolar macrophage morphologic changes induced by BLM-A6]

The morphologic changes of alveolar macrophages (AM) were observed by electron microscopy, computer controlled image analysis and stereoscopy. The results showed that 764-3 had no effect on normal AM morphology and structure, but inhibited the BLM-A6 induced increase of volume, specific surface, and lysosome volume density of AM. At the same time, the spreading ability of AM on the slide was markedly reduced by 764-3, indicating that 764-3 can partially prevent the AM activation caused by BLM-A6 in vitro.

Generation and purification of recombinant fimbrillin from Porphyromonas (Bacteroides) gingivalis 381

Fimbrillin is the major subunit protein of fimbriae from the human periodontal pathogen Porphyromonas (Bacteroides) gingivalis. We describe here the generation and initial characterization of recombinant fimbrillin (r-fimbrillin) isolated from P. gingivalis 381. A fragment of DNA encoding the gene for fimbrillin was generated by polymerase chain reaction and cloned into the expression vector pET11b. Plasmids containing the recombinant gene were transfected into Escherichia coli. Clones were selected on plates for ampicillin resistance and individually screened by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein production after activation with IPTG (isopropyl-beta-D- thiogalactopyranoside). One clone, OW0.2, produced significant amounts of a 42-kDa protein after induction with IPTG. This clone contained the pET11b plasmid with a 1-kb insert that had sequence homology to the gene encoding fimbrillin. The majority of recombinant protein from clone OW0.2 was found in the cytoplasm within inclusion bodies. Protein aggregates were solubilized in 8 M urea, and SDS-PAGE analysis showed two major protein bands, one at 42 kDa and the other at 17 kDa. These two proteins coeluted from a DEAE-Sepharose column at 0.15 M NaCl and were reactive to rabbit antiserum to fimbrillin in a Western blot (immunoblot). A preparation giving a single protein band at 42 kDa in SDS-PAGE was obtained by size fractionation by using continuous-elution electrophoresis. Lymph node cells from animals immunized with either fimbrillin from P. gingivalis or r-fimbrillin showed antigen-specific proliferation to both P. gingivalis fimbrillin and r-fimbrillin in an in vitro recall assay. Therefore, it appears that r-fimbrillin is chemically, antigenically, and serologically identical to fimbrillin isolated from P. gingivalis 381.

The role of activated neutrophils and free radical in the pathogenesis of pulmonary hypertension

In in situ perfused rat lungs, it was demonstrated that the perfusing pressure and permeability of pulmonary capillaries were obviously increased after activated neutrophils (PMNs) were added to the perfusate. The effect of free radicals generated by the xanthine-xanthine oxidase system on isolated rabbit pulmonary arterial ring tension was also observed, and the contractile response was found to be dose dependent: The smaller the vessel diameter, the higher the contractile response. Superoxide dismutase and catalase were able to obviously attenuate the contractile response. The response was endothelium independent, and was influenced neither by indomethacin (cyclooxygenase inhibitor) nor by nordihydroguaiaretic acid (lipoxygenase inhibitor), while removal of Ca from the bath solution or addition of the protein kinase C (PKC) inhibitor "H7" or an antiinflammatory drug (764-3, the effective component of Radix Salvia miltiorrhizae) could significantly inhibit the contractile response. The results suggest that activated PMNs may play an important role in the pathogenesis of pulmonary hypertension.

[Study on hydrolytic kinetics of metronidazole-phosphate in rabbit plasma by HPLC]

A HPLC method for the simultaneous determination of metronidazole and metronidazole-phosphate in rabbit plasma has been established. This method is simple, sensitive, reproducible and has a good linearity. It has been used to study the hydrolytic kinetics of metronidazole-phosphate in rabbit plasma. The results show that hydrolytic process of metronidazole-phosphate in vitro at 37 degrees C follows a first order kinetics with the rate constant 0.016 min-1 and half-life 43 min.

Cell- and heparin-binding domains of the hexabrachion arm identified by tenascin expression proteins

We have produced a set of bacterial expression proteins corresponding to 10 segments of tenascin and two of fibronectin and tested them for heparin binding and cell adhesion. We used polymerase chain reaction cloning to terminate the segments precisely at domain boundaries. Heparin binding activity was mapped to two different tenascin segments: one comprising the fourth and fifth fibronectin type III domains, and to TNfbg, the fibrinogen-like terminal knob. TNfbg, but none of the other tanascin segments, also supported adhesion of primary rat embryo skin fibroblasts. The fibroblasts did not spread on TNfbg but remained rounded. Cell binding to TNfbg occurred in the presence or absence of divalent cations and was not inhibited by RGD peptides, suggesting that integrins are not involved. Fibroblast binding to TNfbg was strongly inhibited by soluble heparin, by treating the cells with heparitinase, or by culture conditions that cause undersulfation of proteoglycans. These observations suggest that cell attachment to TNfbg is mediated by cell surface proteoglycans. We have also made full-length cDNA constructs for the largest and smallest splice variants of human tenascin, as well as one truncated after the 14th epidermal growth factor-like domain, in the pNUT mammalian cell expression vector. Stably transfected baby hamster kidney cell lines secreted large quantities of tenascin, and this was assembled into normal hexabrachions, the arm length corresponding to the construct.

[Effect of 764-3 on ConA receptors on rat alveolar macrophages]

The changes of concanavalin A (ConA) receptors on alveolar macrophage (AM) surfaces were observed by means of ConA-horseradish peroxidase gold labelling techniques. The results were as follows: 1) The average gold particle number on normal AM surfaces was 1.985 +/- 0.097/microns, distributed uniformly; 2) On AM activated by BLMA6, in vitro, this number had increased to 3.909 +/- 0.314/microns, P < 0.001 compared with the normal group; 3) On AM preincubated with 764-3, the average gold particle number was 1.577 +/- 0.090/microns, significantly lower than that in the BLMA6 group. All results suggest that 764-3 might partially inhibit the expression of ConA-R on AM activated by BL-MA6.

Retrovirus-mediated transfer and expression of marker genes in the BN rat acute myelocytic leukemia model for the study of minimal residual disease (MRD)

To study minimal residual disease (MRD) in leukemia, we transferred the Escherichia coli genes encoding beta-galactosidase (lacZ) and neomycin resistance (neo(r)) into the subline LT12 of the Brown Norway rat acute myelocytic leukemia (BNML), employing the retroviral BAG vector. In this way leukemic cells were genetically marked. Ten independent cell lines were characterized during in vitro growth as well as during two subsequent in vivo passages for expression of neo(r) for which the neomycin analogue G418 was used, and for lacZ expression for which the substrate 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) was used. Out of 10 lines, four revealed permanent high expression of lacZ in all cells. In four other lines greatly varying lacZ expression between the individual cells from these lines was observed. In the remaining two lines lacZ expression was gradually lost. In contrast, neo(r) expression was gradually lost in eight out of the 10 lines, particularly rapidly during in vivo passaging. In the remaining two lines neo(r) expression was retained. The genetic modification did not alter the in vitro leukemogenicity of the cells. Long term in vivo expression of neo(r) and lacZ was followed in two selected lines up to 12 subsequent passages, i.e. one from the group of homogeneous high lacZ expression and one from the group of heterogeneous lacZ expression. In both lines lacZ expression was retained whereas neo(r) expression was rapidly lost after the third passage. The feasibility of using genetically marked leukemic cells for studies of minimal residual disease (MRD) was explored by injecting rats with leukemic cells, treating them with chemotherapy at full blown leukemia development to reduce the tumor load, mimicking the induction of a state of MRD and studying lacZ expression at relapse. LacZ expression was evident in 100% of the cells whereas neo(r) expression was lost in a considerable fraction. These results indicate that the viral vector BAG can be used to mark leukemia cells genetically although a selection of clones with the desired stability of long-term expression is required.

An approximation formula for the variance of PET region-of-interest values

An approximation formula for the variance of positron emission tomography (PET) region-of-interest (ROI) values has been developed, implemented, and evaluated. This formula does not require access to the original projection data and is therefore convenient for routine use. The formula was derived by applying successive approximations to the filtered-backprojection reconstruction algorithm. ROI variance is estimated from the product of mean pixel variance within the region and a term accounting for the intercorrelation of all pixel pairs inside the region. The formula accounts for radioactivity distribution, attenuation, randoms, scatter, deadtime, detector normalization, scan length, decay, and reconstruction filter. The algorithm was tested by comparison to the exact ROI variance as calculated with Huesman's algorithm. Tests with scan data from phantoms, animals, and humans obtained on the Scanditronix PC2048-15B tomograph showed the approximation formula to be accurate to within +/-10%

Shift in infrared interference filters at cryogenic temperature

The temperature dependence of the IR interference filters that use lead telluride as a high-index material is measured at various temperatures. Experimental results show that the wavelength and transmission shifts are dominated by the absorption edge and index of refraction of lead telluride, respectively, depending on where the transmission spectrum of the filter is located.

Looking at proteins: representations, folding, packing, and design. Biophysical Society National Lecture, 1992

Looking at proteins is an active process of interpretation and selection, emphasizing some features and deleting others. Multiple representations are needed, for such purposes as showing motions or conveying both the chain connectivity and the three-dimensional shape simultaneously. In studying and comparing protein structures, ideas are suggested about the determinants of tertiary structure and of folding (e.g., that Greek key beta barrels may fold up two strands at a time). The design and synthesis of new proteins "from scratch" provides a route toward the experimental testing of such ideas. It has also been a fruitful new perspective from which to look at structures, requiring such things as statistics on very narrowly defined structural categories and explicit attention to "negative design" criteria that actively block unwanted alternatives (e.g., reverse topology of a helix bundle, or edge-to-edge aggregation of beta sheets). Recently, the field of protein design has produced a rather unexpected general result: apparently we do indeed know enough to successfully design proteins that fold into approximately correct structures, but not enough to design unique, native-like structures. The degree of order varies considerably, but even the best designed material shows multiple conformations by NMR, more similar to a "molten globule" folding intermediate than to a well ordered native tertiary structure. In response to this conclusion, we are now working on systems that test useful questions with approximate structures (such as determining which factors most influence the choice of helix-bundle topology) and also analyzing how natural proteins achieve unique core conformations (e.g., for side chains on the interior side of a beta sheet, illustrated in the kinemages).

[Minimum residual leukemic cells in genetically marked brown Norway rat myelocytic leukemia model]

Different methods were used to detect minimal residual leukemic cells (LT 12 nl), which had been genetically marked with E. coli 1 acZ and neo-gene by retrovirus vector mediated gene transfer. The detection levels of flow cytometry based FDG staining and fluorophotometric method based MUG staining were 10(-3) to 10(-4) and 10(-2) to 10(-3), respectively. The method of G 418 selective agar culture was demonstrated as a 10(-4) to 10(-5) levels for the detection of LT 12 nl residual leukemic cells in bone marrow. The results indicated that the selective agar culture can be used as a sensitive method for the study of minimum residual disease in the BNML leukemia model. We have used the selective agar culture to study the distribution of clonal LT 12 nl cells in BNML during minimum residual disease (MRD). A heterogenous distribution pattern of the clonal leukemic cells was found in the genetically marked BNML leukemia model during the MRD phase.

Digitaloid pregnanes promote potassium-sparing diuresis in the guinea pig

The synthesis of 17 alpha-acetoxy-3 beta-[(beta-D-glucopyranosyl)oxy]- 6 alpha-methylpregn-4-en-20-one, the glucoside of medroxyprogesterone acetate (MPA-glu), is described. MPA-glu and 14-amino-20 beta-hydroxy-3 beta-[(alpha-L-rhamnopyranosyl)oxy]-5 beta, 14 beta-pregnane (LND 623), pregnane glycosides that bind to the digitalis receptor, and digoxin, a cardiac glycoside, were infused intravenously into the anesthetized guinea pig. Each of the three steroids significantly enhanced urinary volume and sodium excretion without affecting blood pressure and creatinine clearance. Potassium excretion was markedly enhanced by digoxin but unaffected by MPA-glu or LND 623. These observations conform to previous work that demonstrated, in the rat, potassium-sparing diuresis by the glucoside of 14 beta-hydroxyprogesterone, a cardiotonic pregnane. There is a dissociation between potency to inhibit [3H]ouabain binding and the extra ATPase actions of the digitaloid pregnanes.

The protective effect of colchicine on bleomycin-induced pulmonary fibrosis in rats

With the purpose of evaluating the therapeutic effect of colchicine on lung fibrosis in rats, bleomycin A5 (BLM-A5) was injected intratracheally to produce a lung fibrosis model. The animals were then treated with colchicine, 50 micrograms/d i.m. One month later, collagen fiber deposition scores (stained by Masson trichrome) were significantly lower in the treated group than in the untreated group (P less than 0.01). This result was proved further by assaying total lung hydroxyproline content (P less than 0.05). Histopathologic findings showed that the proliferation of fibroblasts dropped slightly in the treated group as compared with the untreated group. From this study, we conclude that colchicine has certain antifibrotic effects and may be used in the treatment of pulmonary fibrosis.

[Risk factor for acute viral hepatitis: a case-control study]

One hundred and sixty-two patients with acute viral hepatitis in two hospitals were studied between January and December, 1988. The risk factors, epidemiologic features and prognosis of those patients were investigated by case-control and follow-up study. Among the 162 patients, 37.0% were hepatitis A, 40.7% were hepatitis B, and 19.8% were non-A, non-B hepatitis; there were 4 cases of mixed infection and 3 cases of fulminant hepatitis not included in the study. By simple case-control and logistic regression analysis, the patients of hepatitis A more often had history of personal contact with hepatitis cases (OR = 10.56) and of ingesting some contaminated foods (OR = 4.25); hepatitis B more often had history of personal contact with hepatitis cases in their families or elsewhere (OR = 5.66; OR = 4.30 respectively); and hepatitis NANB more often had history of previous clinical hepatitis episode (OR = 6.56), of personal contact with cases of hepatitis (OR = 3.82) and of receiving a blood transfusion (OR = 16.67). Among hepatitis A, B and NANB cases, sequelae of chronic hepatitis after acute phase were found in 0%, 12.1% and 16.7% of cases, respectively.

Structure of simian virus 40 at 3.8-A resolution

The crystallographically determined structure of simian virus 40 shows that the 72 pentamers of viral protein VP1, which form the outer shell, have identical conformations except for the C-terminal arms of their subunits. Five arms emerge from each pentamer and insert into neighbouring pentamers. This tying together of standard building blocks allows for the required variability in packing geometry without sacrificing specificity.

Finite-element model of the human head: scalp potentials due to dipole sources

Three-dimensional finite-element models provide a method to study the relationship between human scalp potentials and neural current sources inside the brain. A new formulation of dipole-like current sources is developed here. Finite-element analyses based on this formulation are carried out for both a three-concentric-spheres model and a human-head model. Differences in calculated scalp potentials between these two models are studied in the context of the forward and inverse problems in EEG. The effects of the eye orbit structure on surface potential distribution are also studied.

[A comparison of the microvascular architecture of the knee joints of humans and Macaca mulatta]

The blood supply and the microvascular architecture of the knee joint in Macaca mulatta were investigated. 24 lower limb specimens were injected with a barium sulfate suspension via the common iliac artery. The results were then compared with human knee joint data obtained by other authors. We found no evident difference in knee joint blood supply between the two species, but a few variances did exist. Therefore we considered it correct to use the knee joint of the Macaca mulatta as a model in medical experiments, but in an experiment on the regional area or some structures of the knee joint, several variances must be considered before drawing conclusions.

[Effect of liuwei dihuang decoction and its compatible prescriptions on lipid peroxide and lipofuscin]

Our experiment has shown that liuwei dihuang Decoction can decrease the contents of lipid peroxide in the serum as well as lipofuscin in the liver of the older mice to the level of the younger ones, while the two compatible prescriptions derived from the decoction, "Three invigorators" and "Three purges", cannot produce the same effect. All the three forms of prescription have no action on the lipofuscin in the heart.

[Anticancer element selenium in liuwei dihuang decoction]

The contents of selenium in Liuwei Dihuang decoction (six traditional Chinese drugs and their decoction, five decoctions in different compatible ways, a complex decoction of all crude drugs) have been determined by fluorescence spectrophotometric method. The result shows that element selenium is rich in Dihuang. The dissolution ratio of selenium in decoctions of each single crude drug is about 30-40%.

[Comparative study on the inhibitory elastase capacity of fructus Forsythiae, radix Salviae Miltiorrhizae, radix Angelicae Sinensis and Ligustrazini]

In this paper elastase capacity was measured with agar radial diffusion using elastin-agar plate. There was a linear correlation between elatase capacity and diameter of agar radial diffusion. Significant inhibitory effects of Fructus Forsythiae, Radix Salviae Miltiorrhizae, Radix Angelicae Sinensis and Ligustrazini Hydrochloridum on elastase were observed and Fructus Forsythiae proved the most effective.

[Dissolution of metronidazole stilus]

Metronidazole stilus is a new preparation to be inserted into periodontal pockets for treatment of periodontitis. The certificate and file number of approval given to this new product were issued by the Ministry of Public Health in August, 1989. Its shape looks like a toothpick and the width, thickness and length are 1.5mm, 0.7mm and 3 cm, respectively. The content of metronidazole in each cm of the stilus is 2.2 mg. We have studied the dissolution of the new preparation by rotation basket method. The kinetic process of dissolution approximates first order kinetics. The K, t0.5 and t0.9 are 0.0624 min-1, 12.8 and 38.6 minutes, respectively. The requirement is that the dissolved percentage should not be lower than 60% of the added amount in 30 minutes. In order to have a dissolution test similar to that of the stilus in dental pockets, we examined the dissolution in static condition. The results showed that a very high dissolution rate appeared in the beginning, but it decreased quickly, and 71.76% of metronidazole was not dissolved until 48 hours. So one insertion per two days for clinical use is suggested.

[Study on the risk factors of low birth weight]

To detect the risk factors of low birth weight in the newborns, a case-control study was conducted in 5 Health Stations of Donge-heng District of Beijing from Sept 1985 to June 1986. The subjects of study consisted of 84 infants of low birth weight and their parents with 301 controls. A 2 x 2 table analysis was used in screening important factors and multiple logistic regression was employed to estimate the relative role played by these factors. The results revealed that factors, such as height of parents, maternal nutritional status, prematurity, parents' exposure to the chemicals, fathers' smoking habit were risk factors of importance ranked in order.

[Microvascular injury effects and possibility of early anastomosis in the maxillofacial region following high velocity missile wound: an experimental study in dogs]

In order to provide the basis of microvascular anastomosis for reconstruction of maxillofacial defects from firearm injury by using vascularized free tissue transplantation, we studied the mechanism and pathology of microvascular injuries and the possibility of their early anastomosis. The dogs' face were wounded by 0.7 g or 1.03 g steel spheres whose muzzle velocity were 1300 m/s or 1500 m/s. The injury effects of microvascular angiograms were recorded through high speed X-ray camera at the impacting moment the specimens of small vessel were collected for light and electron microscopy at different times after wound. Some dogs were used for performing microvascular anastomosis in the wound region at different times after wound. We found that there were temporary cavity effects in maxillofacial firearm wounds, in and around which small vessel blunt injuries were found, which spread 3 cm from the wound edge. Microvascular anastomosis 3 days after the wound could get higher shortterm patency rate. These results support the conclusion that if we use microsurgical methods to repair defects in maxillofacial firearm wound region, the pedicles of the flap should be laid beyond 3 cm from the wound edge, and the reconstructive operation should be done 3 days after the wound.

[Age-related microvascular changes in human skin]

Microvascular changes in 32 biopsies of normal human skin were observed using electronic computer image analysis. Statistical analysis showed a decrease in microvasculature with increase of age, with significant decreases appearing at ages greater than or equal to 20, suggesting that the changes are closely related to aging of human skin.

[Clinical, immunophenotypic and cell cyclic analysis in chronic lymphocytic leukemia]

15 cases of chronic lymphocytic leukemia (CLL) were immunophenotyped with a panel of monoclonal antibodies. 13 cases were B-CLL, which was characterized by CD20+, HLA-Dr+, SmIg+ and CD5+/Em+. 2 cases were T-CLL, one with Ts phenotype and HLA-Dr+ T-Cll in the other. The ratio of G0 + G1 cells in bone marrow of CLL was 91.1 +/- 2.3% (76.0 +/- 5.1% in controls), while S + G2M cells was 8.9 +/- 2.3% (23.9 +/- 5.1% in controls). The ratios of various cyclic cells were similar in bone marrow and in peripheral blood. Prolymphocytoid transformation developed in the late stage in 3 CLL patients. The clinical course, cytochemistry and immunologic changes in CLL were also analysed.

[Molecular cloning, gene structure and subcellular distribution of 7s RNA of rat liver cells]

The cDNA copy of in vitro polyadenylated 7s RNA from rat liver cells have been cloned and sequenced. One clone (p 24) contains a 7 s cDNA fragment with 180 bp from 3'end. Sequence analysis indicated that 7s RNA in rat liver cells showed at least one nucleotide substitution compared with that in rat Novikoff hepatoma cells. Southern blot of rat liver and hepatoma genomic DNA shows that 7s RNA gene is a multigene family (10-20 copies per haploid genome) and these loci seems not to be clustered, but have a dispersed array in the genome. We have determined the subcellular distribution of 7 s RNA in rat liver cell by means of RNA-excess hybridization. The result indicated that 42% 7s RNA exists in cell nuclei. Dot hybridization to RNA from liver cells and hepatoma cells proved that the normal liver cells contain relatively more 7 s RNA than that in hepatoma cells.

[Tracheo-bronchoplasty: a report of 99 cases]

This paper reported 99 patients (10 with benign lesions and 89 malignant tumors) treated by tracheo-bronchoplasty. Postoperative complications occurred in 11 patients. Of whom 5 died of bronchovascular fistulas, respiratory failure, empyema, or spontaneous pneumothorax. On follow-up, among 13 patients with tracheal carcinoma treated by tracheal and/or carinal reconstructions, 4 lived for more than 5 years, 2 more than 3 years, 1 less than 1 year, and 6 died within 2 years. The survival rates of patients with bronchoplasty for lung cancer were 64.5% and 42.9% at 3 and 5 years, respectively.

[Experimental study of antigastroesophageal reflux by preservation of the lower esophageal sphincter]

Gastroesophageal reflux and its resultant esophagitis are common complications following removal of the middle and lower part of the esophagus as well as the gastric cardia with reconstruction by simple esophagogastrostomy. Twenty-one dogs were randomly divided into 3 groups: (1) LES preserving group; (2) Nissen's fundoplication group; (3) Sweet's esophagogastrostomy group. Results by esophageal manometry, X-ray video tape recorder, and pathological examination respectively, 3 months postoperatively were compared. Esophageal manometry showed that the pressure of the preserved LES was still present. X-ray video tape recorder revealed that antireflex function was present in the preserved LES. Pathological examination confirmed no signs of reflux esophagitis in the mucosal specimen of the preserved LES group. We concluded that LES is the main barrier of gastroesophageal reflux. The intrathoracic LES could still have the function of anti-reflux.

Bleomycin hypersensitivity in dyskeratosis congenita fibroblasts, lymphocytes, and transformed lymphoblasts

We studied the responses of several dyskeratosis congenita (DC) cell lines to the DNA strand-cleaving and base-damaging agent bleomycin. Fibroblasts, peripheral blood lymphocytes, and transformed lymphoblasts of six DC patients and an obligate DC heterozygote showed more chromatid breaks than did respective controls exposed to various concentrations of bleomycin during the G2 phase of the cell cycle (P less than 0.0001). Unsynchronized DC fibroblasts in culture also showed decreased survival, compared to normals, following bleomycin treatment. DC lymphocytes treated with bleomycin for the final 24 h of culture showed more chromatid- and chromosome-type damage than did normals (P less than 0.0001) or G0-treated DC lymphocytes. Spontaneous chromosome breakage was normal in all six DC cell lines. The ability to distinguish affected and heterozygous DC cells without spontaneous chromosome instability from normals on the basis of their bleomycin hypersensitivity provides a marker for future studies of the pathogenesis of this disorder.