Evidence from X-ray absorption fine structure spectroscopy for significant differences in the structure of concanavalin A in solution and in the crystal

We have used X-ray absorption fine structure spectroscopy (XAFS) to study and compare the structure of concanavalin A in crystals and in aqueous solution. Significant differences were found between crystal and solution in the configuration of the transition-metal site of the protein. The metal has six ligands in solution but only five in the crystal. The ligand bond lengths are shorter in the crystal than in solution. The vibrational disorder in the crystal and possibly the corresponding bond length show a negative temperature dependence whereas in solution they vary normally with temperature. The anomalous temperature dependence in the crystal suggests that as the temperature decreases the protein molecules are subject to additional stresses, which are transmitted as a tensile stress at the metal site leading to distorted geometry and lengthening and weakening of metal-ligand bonds.

Transfer of adriamycin resistance by fusion of Mr 170,000 P-glycoprotein to the plasma membrane of sensitive cells

One of the characteristics of multidrug-resistant mammalian cells is the presence of a glycoprotein of approximately Mr 170,000 in their cell membrane. Termed P-glycoprotein, this glycoprotein is thought to be the gene product of an amplified gene cloned and sequenced from a cell line (LZ) which is highly resistant to Adriamycin and cross-resistant to actinomycin D, colchicine, and vincristine. Resistance to Adriamycin has been induced in sensitive cells by chromosome or gene transfer. We now show that P-glycoprotein isolated from LZ cells and fused to sensitive V79 Chinese hamster cells renders the latter transiently resistant to Adriamycin. Incorporation of P-glycoprotein was confirmed by immunoperoxidase staining of fusion products following treatment with antibody to P-glycoprotein and by Western blots of membrane preparations from fusion products. These results suggest that P-glycoprotein is one of the important factors in the expression of Adriamycin resistance and provide added confirmation that it may be the important product of gene amplification in multidrug-resistant cells. The results also suggest that the cell membrane may be one of several targets for Adriamycin cytotoxicity and that P-glycoprotein may be a binding site for Adriamycin, rendering the latter ineffective in registering sufficient membrane damage for cell killing.

Determination of nornicotine in smokers' urine by gas chromatography following reductive alkylation to N'-propylnornicotine

A sensitive gas chromatographic assay has been developed to measure concentrations of nornicotine in human urine. A structural analogue, 5-methylnornicotine, is used as an internal standard. Both nornicotine and the internal standard were converted to the corresponding N'-propyl derivatives using a novel reductive alkylation procedure. The N'-propyl derivatives have good chromatographic properties, which allows quantitative measurement in the low nanograms per milliliter range. Concentrations of nornicotine in smokers' urine were quantitated and compared with the concentrations of nicotine and its metabolites, cotinine, nicotine-N-oxide and cotinine-N-oxide.

[A preliminary report on the investigation of medicinal plant resources in the Liupan Mountains of Ningxia Hui Autonomous Region]

In this paper, 423 species of medicinal plants belonging to 94 families in Liupan Mountains of Ningzia Hui Autonomous Region have been reported, of which 403 species belonging to 79 families are medicinal spermatophytes. The paper may serve as a reference for medical authorities in developing and utilizing plant resources.

[Studies on ultraweak luminescence of bacteria]

Ultraweak luminescence of Escherichia coli, Bacillus subtilis and Brevibacterium ammoniagenes was measured with high sensitive single photon counting equipment (Made in China). The results obtained from ultraweak luminescence of as above three bacterial strains were as follows: spectral distribution curves, photon emission kinetic curves or emission intensity and its qualitative relationship between intensity and bacterial counts.

[Analysis of causes of malaria outbreaks in Yunnan Province, 1981-1985]

The incidence of malaria in Yunnan province has decreased year by year in recent years. However, focal outbreaks in small scale still occurred every year. The average morbidity in villages with outbreaks was 15.22-70.82%, and the plasmodium positive rate 6.36-34.69%, in which the percentage of Plasmodium falciparum 34.55-63.63%. The main cause of outbreaks was the existence of residual source of malaria infection and the concomitance of high density of Anopheles. Eradication of the vector and eradication of the course of infection were taken as the composite preventive and control measures which gave a satisfactory effect.

Demonstration of lipid A-binding proteins on murine lymphoma cells using R-mutant gram-negative bacteria as a detector

Some R-mutant Escherichia coli and Salmonella heavily adhered to murine lymphoma cells of B cell and T cell lineages. This adhesion was primarily mediated by membrane-localized proteins on tumor cells, which bind the polymyxin B-reactive hydrophilic structure of lipis A on bacteria. SDS-PAGE analysis of tumor cell membranes showed that proteins or glycoproteins of MW = around 45Kd, 25-35Kd and around 15Kd preferentially bind lipid A. Various lymphoma cell lines binding the bacteria at different levels possessed lipid A-binding proteins of slightly different compositions. We conclude that lymphoma cells carry not a single but a group of lipid A-binding proteins in their membranes.

A method to evaluate the antioxidant system for radicals in erythrocyte membranes

The erythrocyte defense system against cellular oxidants is complex and efficient. Free radicals generated in cell membranes, however, are relatively sequestered from the cell's antioxidant mechanisms. When an oxidant challenge exceeds the capacity of the erythrocyte's antioxidant system, membrane damage may occur, causing red cell destruction and hemolytic anemia. In this study, we present a method for monitoring radical reduction in erythrocyte membranes, using fatty acid spin labels with nitroxide radicals on the hydrocarbon chains. About 50 microL of packed (about 5-6 x 10(8)), carbon monoxide (CO)-gassed red blood cells are used. The electron paramagnetic resonance signals of the 5-doxylstearic acid spin labels in the intact cells are obtained as a function of time, at 37 degrees C over a period of 2 h. The pseudo first-order rate constant for reduction of the spin label in normal adult intact cells under our experimental conditions is 4.3 +/- 1.8 x 10(-3)/min. The reproducibility and variability of the measurements are discussed. Since the measurements we describe reflect the extent of radical reductions occurring in cell membranes, we suggest that this method can be used to measure the ability to defend oxidants in membranes of erythrocytes with defective antioxidant systems. This method is particularly useful for measuring the modification of the antioxidant system toward radicals in membranes by drugs, chemicals, or environmental toxins.

Evacuation of hypertensive intracerebral hematoma by a stereotactic technique

30 patients with a hypertensive intracerebral hematoma were treated by stereotactic evacuation between 1986 and 1988. There were 20 males and 10 females; their ages ranged from 37 to 78 years. The time interval from onset to operation was in 16 patients 24 days and in 14 patients 2-7 days. In 19 patients the hematoma was found in the internal capsule, in 5 in the cerebellum, in 4 in the subcortex, and in 2 in the brain stem. The operation was performed with a Leksell computed tomography guided stereotactic apparatus and a Backlund hematoma evacuator. More than 80% of the hematoma could be aspirated in 20 patients and 60-80% in 10. 29 patients are alive, and 1 patient died.

Centrifugal counter-current partition chromatography with helical coil rotor. Simplified counter-current chromatography with a rotating face-seal

A centrifugal counter-current partition chromatograph has been developed and tested in order to simplify earlier counter-current chromatographic (CCC) procedures. It includes a helical coil rotor and a rotating face-seal. The rotor is designed to be adapted in an ordinary laboratory centrifuge for toroidal coil CCC. Twisting between the inlet and outlet tubing is avoided by using the rotating seal in the rotor. The seal is placed between the rotor, on which helical coils are mounted, and a newly designed centrifuge lid. This chromatographic rotor, rotating simply around its own axis, has simplified a previous CCC device in which a coil planet mechanism is used to avoid tube twisting whilst retaining the capability for chromatographic separations. Results for separations of nystatin, dinitrophenylamino acids and Poly I:C were comparable to those obtained by liquid chromatography and the previous CCC procedure.

Studies on monoclonal anti-idiotypic antibodies to human B cell leukemia

Murine immunocytoma cell line, NS-1, was fused with spleen cells of Balb/C mice which had been stimulated by tolerogenic disaggregated human gamma globulin and immunized by purified serum IgM from the patient with chronic B cell leukemia (B-CLL). 10 hybridoma cell lines secreting monoclonal anti-idiotype (anti-Id) antibodies to human CLL were obtained. The McAbs were subclasses belonging to IgM and of IgG mouse. Specificity and biologic characters of the monoclonal anti-Id antibodies from culture fluid or ascites were assayed by ELISA, indirect mixed ELISA sandwich, ELISA inhibition, immunofluorescence (IF) and IF inhibition. The study also proved that monoclonal anti-Id antibodies could react with homologous IgM, but not with Ig from normal donors or a panel of patients with myeloma. The results of IF and IF inhibition assay showed that monoclonal anti-Id antibodies were bound to lymphocytes of patient with B-CLL. Their reactivity was inhibited by homologous IgM, but not by lymphocytes of patients with ALL or lymphoma. Monoclonal anti-Id antibodies were heterogenous reactive patterns with cell lines in vitro.

[Pathologic studies of pituitary changes with hypertensive hemorrhage]

The pituitarism of 20 deaths from hypertensive cerebral hemorrhage at different periods were studied pathologically. No matter where the location of intracerebral hemorrhage may be, and how much the content of hemorrhage may involve, usually there are some changes in pituitary could be observed. Early period of the cerebral hemorrhage show the expansion, congestion and edema interstitial venous sinus of anterior pituitary; after then empty bulb degeneration of anterior spongy degeneration and necrosis etc may be taken place. The pathologic changes of pituitary is induced by the following three factors: 1. Blood penetrates into cerebral ventricle and pituitary. 2. Blood mass was formed after hemorrhage--increment in intracerebral pressure pressed by cerebral herniation. 3. The disturbance caused by cerebral blood circulation after cerebral hemorrhage makes the pituitary primary plexus obstructed and pituitary destroyed.

Organization of Genes Required for the Oxidation of Methanol to Formaldehyde in Three Type II Methylotrophs

Restriction maps of genes required for the synthesis of active methanol dehydrogenase in Methylobacterium organophilum XX and Methylobacterium sp. strain AM1 have been completed and compared. In these two species of pink-pigmented, type II methylotrophs, 15 genes were identified that were required for the expression of methanol dehydrogenase activity. None of these genes were required for the synthesis of the prosthetic group of methanol dehydrogenase, pyrroloquinoline quinone. The structural gene required for the synthesis of cytochrome c L , an electron acceptor uniquely required for methanol dehydrogenase, and the genes encoding small basic peptides that copurified with methanol dehydrogenases were closely linked to the methanol dehydrogenase structural genes. A cloned 22-kilobase DNA insert from Methylsporovibrio methanica 81Z, an obligate type II methanotroph, complemented mutants that contained lesions in four genes closely linked to the methanol dehydrogenase structural genes. The methanol dehydrogenase and cytochrome c L structural genes were found to be transcribed independently in M. organophilum XX. Only two of the genes required for methanol dehydrogenase synthesis in this bacterium were found to be cotranscribed.

Identification of amino acid sequences that can function as translocators of beta-lactamase in Escherichia coli

A plasmid vector, pYZ1, was constructed which lacks most of the beta-lactamase signal-peptide coding region, but has a unique EcoRI site spanning codons 2 and 3 of the resultant cytoplasmic beta-lactamase derivative. Short quasi-random DNA sequences were cloned into the EcoRI site and Escherichia coli transformants in which some translocation of beta-lactamase across the cytoplasmic membrane was restored were selected by their ability to survive and form colonies on plates containing a low level of ampicillin. About 15-20% of all in-frame inserts restored some beta-lactamase translocation and the salient feature of these sequences was their marked hydrophobicity. These results are discussed in the light of a similar study in which sequences able to function as translocators of invertase in yeast were cloned and analysed (Kaiser et al., 1987).

Lysine-60 in the regulatory chain of Escherichia coli aspartate transcarbamoylase is important for the discrimination between CTP and ATP

Lysine-60 in the regulatory chain of aspartate transcarbamoylase has been changed to an alanine by site-specific mutagenesis. The resulting enzyme exhibits activity and homotropic cooperativity identical with those of the wild-type enzyme. The substrate concentration at half the maximal observed specific activity decreases from 13.3 mM for the wild-type enzyme to 9.6 mM for the mutant enzyme. ATP activates the mutant enzyme to the same extent that it does the wild-type enzyme, but the concentration of ATP required to reach half of the maximal activation is reduced approximately 5-fold for the mutant enzyme. CTP at a concentration of 10 mM does not inhibit the mutant enzyme, while under the same conditions CTP at concentrations less than 1 mM will inhibit the wild-type enzyme to the maximal extent. Higher concentrations of CTP result in some inhibition of the mutant enzyme that may be due either to hetertropic effects at the regulatory site or to competitive binding at the active site. UTP alone or in the presence of CTP has no effect on the mutant enzyme. Kinetic competition experiments indicate that CTP is still able to displace ATP from the regulatory sites of the mutant enzyme. Binding measurements by equilibrium dialysis were used to estimate a lower limit on the dissociation constant for CTP binding to the mutant enzyme (greater than 1 x 10(-3) M). Equilibrium competition binding experiments between ATP and CTP verified that CTP still can bind to the regulatory site of the enzyme. For the mutant enzyme, CTP affinity is reduced approximately 100-fold, while ATP affinity is increased by 5-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrolyte, urea, and water transport in a two-nephron central core model of the renal medulla

A one-nephron model has been extended to include both short-looped and long-looped nephrons. Variables are volume flow, Na+, K+, Cl-, urea, hydrostatic pressure, and electric potential. The ratio of short-to-long-looped nephrons, one of the parameters of the model, is 5 to 1. With either rabbit or hamster permeability data from perfusion experiments, the model develops an osmolality of approximately 600 mosmol/l at the junction of inner and outer medulla but no osmolality gradient in the inner medulla. With the rabbit data, osmolalities in excess of 1,000 mosmol/l can be generated in the papilla with no active transport if urea permeabilities are less than 10(-5) cm/s; with the hamster data, electrolyte permeabilities must also be reduced. With these modified parameters, urea concentrations are less in the long loops than has been found on micropuncture. These can be increased to experimental levels by increasing the urea permeability and decreasing the hydraulic permeability of thin descending limbs in the inner half of the inner medulla, but to maintain loop osmolality at 1,000 mosmol/l it is necessary to postulate active NaCl transport in thin ascending limbs in the outer half of the inner medulla. This gives an alternative mode of concentration without active transport in the inner half of the inner medulla, in which electrolytes diffuse out of and urea diffuses into both limbs of Henle's loop and mix in the core with urea and water entering from the collecting duct. Concentration in either mode requires significant modification of perfusion data.

Studies on biological characteristics and modulating factors of long-term cultured bone marrow cells of a myeloma patient in vitro

In the present study we cultured in vitro bone marrow cells from a patient with multiple myeloma (IgD) and researched into the modulation of supernatant media of various leukemic lines on the growth of culture cells. Cells in the cultures were studied for their morphological, biochemical, immunological and ultrastructural features. Drug sensitivity assay was also performed. The results showed that supernatant media of 6 cell lines promoted cell growth, but most remarkable stimulating activity was displayed by supernatant media from U937 and CEM. Cell cloning effect attained to more than 90%. Cultured cells possessing biological characteristics of malignant cells were probably malignant cells from B cell lineage. This study indicated that long-term cultures of marrow cells might provide a tool useful for clinical and laboratory purpose and a method for studies on pathogenesis, regulation of hematopoiesis, cell differentiation and guide-way drugs.

Lunar phases, myocardial infarction and hemorrheological character. A Western medical study combined with appraisal of the related traditional Chinese medical theory

Lunar phases and their connections with acute myocardial infarction (AMI) and hemorrheological character (HCh) are studied with the lunar calendar (LC) instead of the solar calendar. AMI onset is maximal on the 1st day of the LC month, decreasing with an obvious trough around the 15th day. After the 15th day, occurrence increases gradually. The end and beginning of the lunar months show sharp peaks of AMI incidence. This study shows also that HCh variations have similar LC monthly rhythms. Our investigation demonstrates the correctness of traditional Chinese medical theory. This monthly rhythm forecasts the onset of AMI peaks and contributes to the secondary prevention of coronary heart disease (CHD).

Electrode system for determination of microbial cell populations in polluted water

Microbial cell populations in polluted water were determined by using a fuel cell-type electrode. The electrode was composed of a Pt anode, a Pt-K3Fe(CN)6-K4Fe(CN)6 cathode, and a cation-exchange membrane for separating two electrode compartments. The principle of microbial cell number determination is based on sensing a redox dye reduced by microorganisms with the electrode. Sample solutions containing microorganisms, a redox dye (thionine), and peptone were purged with oxygen-free nitrogen during the determination. A linear relationship was obtained between the increasing rate of current and the number of microbial cells measured by the colony count method above 10(4) cells per ml. The determination time varied with the number of microbial cells determined from 20 to 60 min for 3.6 x 10(6) and 3.6 x 10(4) cells per ml, respectively.