[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.