Molecular cloning of a rhodopsin gene from salamander rods

PURPOSE

Salamander photoreceptor cells have been used widely as models in vision research. However, the salamander opsin genes had not been cloned. The purpose of this study was to clone a salamander rhodopsin and to determine its primary structure and cell type-specific expression.

METHODS

Using salamander retina RNA as a template and Xenopus rhodopsin-specific oligonucleotides as primers, reverse transcription and polymerase chain reaction (RT-PCR) were used to amplify and clone a rhodopsin cDNA fragment. This fragment was used as a probe to isolate a full-length cDNA of the rhodopsin from a cDNA library of salamander retina. The dideoxynucleotide chain termination method was used to determine the nucleotide sequence. Single rod and cone cells were isolated by micromanipulation, and the absorbance spectra of the rod outer segments were measured with a photon-counting microspectrophotometer. Individual rod and cone cells were lysed for RT-PCR and Southern blot analysis to detect cell-specific expression of this gene.

RESULTS

A 1.2 kb rhodopsin cDNA containing the full-length coding region of rhodopsin has been cloned and sequenced from the larval tiger salamander, Ambystoma tigrinum. This cDNA encodes 354 amino acids that, by hydropathy profile, could form seven transmembrane domains characteristic of other rhodopsins. Sequence identity was found with other amphibian rhodopsins at the nucleic acid (82% to 83%) and the amino acid (88% to 89%) levels. Key amino acids critical for structure and function of rhodopsin have been retained. The mRNA of this rhodopsin was identified in red rod cells (lambda max 506 nm). No expression of the gene was detected in cone cells.

CONCLUSIONS

The cloned rhodopsin is a newly isolated member of the G protein-coupled receptor superfamily. This protein is expressed in rods but not in cones.

[Specific binding of human bone morphogenetic protein (2A) with mouse osteoblastic cells]

Human bone morphogenetic protein 2A (hBMP2A) cDNA terminal S67 nucleotides were cloned and expressed in a phage display vector pCSM21. Human BMP2A C-terminal peptide displayed on the surface of the phage can bind specifically to the surface of mouse osteoblastic cell (MC3T3) membrane. ELISA assay showed a positive signal of the binding by using antibody against M13 phage gene 8 protein. After labeling with 3HTdR, the counts of the binding groups were 3 to 10 times higher than the control groups. It suggests that the surface of MC3T3 cells exist the receptor for hBMP2A.

Voltage- and Ca(2+)-gated currents in zebrafish olfactory receptor neurons

Voltage- and Ca(2+)-gated currents were recorded from isolated olfactory receptor neurons (ORNs) of the zebrafish Danio rerio using the whole-cell voltage-clamp technique. Zebrafish ORNs had an average capacitance of 0.66 pF and an average apparent input resistance of 8.0 G omega. Depolarizing steps elicited transient inward currents followed by outward currents with transient and sustained components. The transient inward current (INa) was sensitive to 1 mumol l-1 tetrodotoxin, activated between -74mV and -64mV, and reached half-maximal conductance at -28 mV. Its peak amplitude averaged -101pA. Steady-state inactivation of INa was half-maximal at an average test potential of -78mV and recovery from inactivation proceeded with two time constants averaging 23 ms and 532 ms. A sustained, Co(2+)-sensitive current (ICa) activated between -44mV and -34mV and reached a peak amplitude averaging -9pA at -14mV. Outward currents were carried by K+, based on the reversal potentials of tail currents, and consisted of a Ca(2+)-dependent K+ current, a delayed rectifier current (IDR) and a transient K+ current (IA). The Ca(2+)-dependent K+ current (IK(Ca)) activated between -44mV and -34mV, whereas IDR and IA activated between -34mV and -24mV. In summary, zebrafish ORNs possess a complement of gated currents similar but not identical to that of ORNs from other vertebrates and which appears well suited for encoding a graded receptor potential into a train of action potentials.

[High homology between antigen of HFRSV with anti-idiotype antibody against HFRSY]

OBJECTIVE

To detect the structural characterization of genes of the anti-idiotype antibody and the antigen.

METHODS

The hybridoma (C8) secreted the anti-idiotype human McAb against hemorrhagic fever virus (HFRSV). The variable region genes of heavy and light chain of the anti-Id huMcAb were cloned. The homology was analysed between the variable region genes and the genes of HFRSV.

RESULTS

The 45-55 amino acids of VH and 58-68 amino acids of VL were highly homologic to the 447-457 amino acids of G2 protein in Hantaan virus. And the homologeneous regions were similar in secondary structure of the three proteins.

CONCLUSION

There is a molecular basis in the anti-idiotype antibody imaging antigen.

Prevention of Th1 response is critical for tolerance

We investigated the role of Th1 ad Th2 cytokines in rejection and tolerance using the neonatal tolerance model. We reported previously that lymph nodes that drained immunogen-bearing tolerant grafts produced a 10- to 100-fold higher ratio of interleukin (IL)-4 to interferon (IFN)-gamma compared with lymph node cells from rejected grafts. Moreover, because neonatal antigen exposure triggers allospecific Th2 CD4 memory cells, whereas antigen exposure during adulthood triggers Th1 CD4 memory cells, we speculated that immunoredirection toward Th2 and away from Th1 functions as another mechanism of tolerance. To test the immunoredirection hypothesis, we examined whether recovery of Th1 cytokine responses abrogates tolerance. We now show that treatment with exogenous IFN-gamma at the time of neonatal priming recovered mixed lymphocyte reaction hypoproliferation and restored the ability of mice to reject skin grafts. Mice that received IFN-gamma at the time of neonatal priming produced more IFN-gamma and contained more A/J-reactive IFN-gamma producing CD4 cells compared with untreated neonatal primed mice, but failed to recover A/J-specific INF-gamma-producing CD8 cells or CTL responses, which suggests that graft rejection occurred via Th1 CD4 cells. Interestingly, draining lymph node cells from rejected grafts in IFN-gamma-treated neonatal primed mice also produced more IL-4, compared with cells from healthy grafts on untreated neonatal primed mice. Nonetheless, lower IL-4 to IFN-gamma ratio predicted graft rejection and higher ratios predicted acceptance. We conclude that neonatal tolerance depends on the ability to block generation of allospecific Th1 responses that lead to rejection. Thus, immunoredirection involves both the inhibition of Th1 and expansion of Th2 immune responses.

Enhanced field strength and resolution in gel electrophoresis upon substitution of buffer by histidine at its isoelectric point

Gel electrophoresis in isoelectric buffers, recently introduced by R. Westermeier and H. Schickle (Electrophoresis '95, Paris, Abstract No.3, 1995), was applied to the automated HPGE-1000 apparatus in the expectation to be able to increase the field strength under the limiting conditions of heat dissipation capacity and voltage of that apparatus. A previous attempt to achieve that aim by reduction of gel thickness had not yielded more than a twofold increment in resolving power. Replacing 0.2 X Tris-boric acid-EDTA (TBE) buffer, conventionally applied in the apparatus at 15 V/cm, by 0.05 M histidine, pH 7.6 (close to the pI of 7.47), allows one to increase the field strength to 60 V/cm, thus providing a nearly fivefold increment in resolution under otherwise identical conditions (fluorescein carboxylate-labeled conalbumin-sodium dodecyl sulfate (SDS) and soybean trypsin inhibitor-SDS samples, 10 degrees C, 4% MetaPhor agarose). An additional decrease in band dispersion can be obtained by decreasing the starting zone width through buffer dilution in the sample phase.

[An experimental study on corneal collagen shield vehicle for delivery of pilocarpine]

OBJECTIVE

The study was designed to clarify the role of corneal collagen shield made in China as a drug vehicle for the delivery of pilocarpine in different ways.

METHODS

80 eyes of New Zealand white rabbits were randomly divided into three groups, corneal collagen shield immersed with pilocarpine, corneal collagen shield with topical application of pilocarpine and synthetic collagen pilocarpine shield. At 0.5, 1, 3 and 6 hours after the delivery, the aqueous concentrations of pilocarpine and the pupillary sizes of all the eyes were measured.

RESULTS

This study showed that shortly after the delivery of pilocarpine in the 3 groups, in spite of difference in ways of its delivery, its aqueous concentrations reached a relatively high level and maintained for more than six hours, the shield acting as a temporary "drug source". The aqueous pharmacokinetics of corneal collagen shield for pilocarpine delivery was consistent with the first-order kinetics and it was confirmed by the observations of miotic response.

CONCLUSIONS

The corneal collagen shield made in China is a fine vehicle for drug delivery.

A new cysteine-rich protein-encoding gene family in Giardia duodenalis

We have cloned a gene, CRP65, from genomic DNA of Giardia duodenalis (Gd) which contains four 228-bp tandem repeat units between a short (48bp) 5' and long (942 bp) 3' non-repeat region. CRP65 encodes a Cys-rich protein (CRP) with the typical transmembrane domain and CXXC amino acid (aa) motif of Gd CRP. Comparison of the nucleotide (nt) and deduced aa sequences of CRP65 and a gene we cloned previously. CRP136, indicates that the genes are highly homologous in the entire non-repeat regions, but not in the repeat regions. The repeat unit of CRP65 was found to be homologous to epidermal growth factor (EGF)-like domains from different proteins. Analysis of Gd genomic DNA showed that there are multiple copies of CRP65 and each copy varies in the number of repeat units, as well as in certain restriction sites in the units. In Gd strain WB-1B, a 2.0-kb transcript encoded by the gene was expressed, while in a metronidazole-resistant line (WB1B-M3) induced from WB-1B, two longer transcripts (5.5 and 7 kb) were expressed. Based on our results, we suggest that there is a unique CRP family in the Gd genome, whose members, including CRP65 and CRP136, carry various repeat units within a highly conserved 'cassette'. CRP65 may be involved in EGF-like interactions with the host proteins.

Mapping variation in chromosome homologues of different Giardia strains

A landmark physical map of the 2-Mb chromosome of the Giardia duodenalis cloned line WB-1B, constructed using randomly cloned, chromosome specific markers, was used to compare the organisation and map order of the equivalent chromosome in other strains. A representative marker from each of the 13 NotI segments of the 2-Mb chromosome was hybridized to NotI cleavages of whole chromosomes of the other strains. Two strains, one isolated from a human, and one from a cat, had the same chromosome hybridization patterns as WB-1B. A strain isolated from a sheep, had one NotI chromosome 5 segment larger than WB-1B. Two additional strains isolated from a calf and a human had significantly different NotI cleavage patterns from the previous strains and shared no similar-sized chromosome NotI segment from their 2Mb chromosome homologues and only one in common with WB-1B. In one strain, two markers from the same WB-1B NotI segment did not hybridize suggesting deletion events have occurred. The order of some NotI segments within the 2Mb chromosome homologue was maintained, as determined from partial NotI chromosome cleavages, while in the most divergent of strains internal chromosome rearrangements and deletions were evident. All but one of the 2Mb WB-1B chromosome markers examined hybridized to a single chromosome band in all strains. Thus, while Giardia chromosomes vary in size, copy number and organisation, some linkage of markers is apparently maintained in isolates from disparate hosts and localities. We have therefore generated a genetic analysis system for Giardia with landmark maps using representative markers to replace the paucity of classical genetic markers and mutants. This approach is being extended to the complete genome.

[Intracavitary microwave hyperthermia combined with external irradiation in the treatment of esophageal cancer]

A randomized trial of intracavitary microwave hyperthermia combined with external irradiation (R + H) versus radiation (R) alone in the treatment of esophageal cancer was performed from Feb. 1986 to Feb. 1988. In the R group, radiation was given by 8 MV X-ray with 2 Gy/fraction, 5 fractions per week with a total dose of 60 Gy/6 weeks. In the R + H group, the radiation was given as R group but with a total dose of 40 Gy/4 weeks. Intracavitary 915 MHz microwave hyperthermia was given with a nominal temperature of 43.5 degrees C at the margin of the tumor surface, 45 minutes/session, 1-2 sessions/week for 4-8 sessions. The 1-, 3-, and 5-year survival rates in R + H group were 81.2% (48/59 cases), 42.4% (25/59) and 23.7% (14/59), while in the R group 59.0% (39/66 cases), 24.2% (16/66) and 16.7% (11/66) respectively. The differences in 1- and 3-year survival rates were statistically significant (P < 0.05) between the 2 groups. Using the thermal dose T90 analysis, after the cases with T90 < 43 degrees C (insufficient thermal dose) were eliminated, 52 cases with T90 equal to or higher than 43 degrees C had 1, 3, and 5 year survival rates of 84.6%, 44.2% and 26.9%, respectively. Statistically significant differences in the 2 groups were also limited only to 1- and 3-year survivals. Higher 5-year survivals is anticipated if more cases are studied.

Expansion of memory Th2 cells over Th1 cells in neonatal primed mice

BALB/c mice primed with CAF1 splenocytes during the neonatal stage developed A/J-specific tolerance with prolonged survival (> 60 days) of A/J skin grafts. Mice failed to develop A/J-specific cytotoxicity, but rejected third-party skin grafts and generated appropriate third-party cytotoxic T cell responses. We demonstrated previously that graft acceptance was associated with enhanced interleukin (IL)-4 and diminished interferon [IFN]-gamma tolerogen-specific cytokine production, whereas third-party graft rejection was associated with the opposite pattern of cytokine production. We now report that neonatal mice do not mount mixed lymphocyte reaction responses against A/J, but the mice contain a higher percentage of IL-4-producing cells that were characterized as CD4+Mel-14lo cells. Although alloantigen priming of both neonatal and adult control mice expands the CD4+Mel-14lo subset, CD4+Mel-14lo cells from neonatal primed mice produce significantly higher levels of IL-4 and IL-10 and lower IFN-gamma, whereas CD4+Mel-14lo cells from adult primed mice produce mainly IFN-gamma. Moreover, enzyme-linked spot immunosorption analysis demonstrates that, compared with adult primed mice, neonatal primed mice contain more IL-4-producing CD4 cells and less IFN-gamma-producing cells, which indicates that neonatal antigen exposure induces and expands alloreactive Th2 memory CD4 cells. The addition of neutralizing antibodies against IL-4 and IL-10 to primary MLR failed to recover IFN-gamma by CD4+Mel-14lo cells, but cells secreted IFN-gamma after a second in vitro restimulation with tolerogen, which indicates that CD4 cells from neonatal tolerant mice have the capacity to differentiate into Th1 cells. In summary, neonatal tolerant mice contain higher ratios of Th2/Th1 CD4 cells, and the Th2 cytokines function to maintain the ratio by inhibiting Th1 differentiation.

CD4 Th2 cells do not functionally suppress CTL generation in neonatal tolerant mice

Injecting semiallogeneic CAF1 spleen into BALB/c newborn mice renders mice tolerant, and the majority of mice show prolonged survival of tolerogen-bearing A/J skin grafts. Moreover, graft survival is associated with enhanced Th2 cytokine responses and graft rejection with Th1 cytokine responses. To further delineate the mechanisms of tolerance, we evaluated CTL responses and found that 74% of neonatal primed mice failed to generate A/J-specific CTL responses, as determined by standard CTL assays and pTc3 frequency analyses. CTL unresponsiveness coexisted with an enhanced tolerogen-specific Th2 memory cytokine profile; spleen cells from neonatal primed mice secreted more interleukin (IL)-4 and less IL-2 and interferon (IFN)-gamma in MLR cultures compared with either adult primed or naive controls. We therefore examined the hypothesis that enhanced Th2 cytokine levels prevent the generation of tolerogen-specific CTL. Adding neutralizing antibodies to IL-4 and IL-10 recovered IFN-gamma production in vitro but not A/J-specific CTL response. In addition, CD4 cells from neonatal primed mice provided help for primary or secondary CD8 CTL generation, which suggests that the enhanced Th2 cytokine profile does not actively suppress CTL generation. Furthermore, CD4 cells from adult primed mice failed to restore the A/J-specific CD8 CTL generation of neonatal primed mice. The results show that failure to develop A/J-specific CTL reaction occurs without suppression by the enhanced Th2-type responses and imply that either deletion or anergy mechanisms block CTL generation. Therefore, neonatal alloantigen exposure not only shifts the development of alloreactive CD4 cells toward Th2, but also blocks development of alloreactive CD8 CTL in this strain combination.

A quantitative study on the effect of organic modifiers in micellar electrokinetic chromatography

A quantitative study was made on the effect of organic modifiers in micellar electrokinetic chromatography (MEKC). A linear relationship between 1/k' and organic modifier concentration ([L]) at lower concentration range was derived and experimentally verified. This linearity was also examined at higher concentrations of organic modifier. The results showed that the linear relationship between 1/k' and [L] can only be observed under the situation that no significant change on micellar structure occurs upon the addition of organic modifiers. The mobility ratio of the solute which characterizes the properties of the solute was found to be mainly independent of [L]. A resolution equation for the neutral solutes was also derived in term of mobility ratio.

Effects of long-term acclimatization in lowlanders migrating to high altitude: comparison with high altitude residents

The physiological response to submaximal and maximal exercise was assessed in lowlanders and Tibetans at low (500 m above sea level) and high altitude (HA, 3,680 m). The times spent at HA by the lowland migrators was 8 days (n = 60), 7 months (n = 60, same group), 15 months (n = 29) and 27 months (n = 29). After the 15-month stay at HA, the maximal oxygen uptake (VO2max) and maximal heart rate of the lowland migrators almost reached those of the HA native residents (Tibetans, n = 57), but their total work capacity and the gross efficiency (eta) of mechanical work remained lower than those of the Tibetans. The rate of VO2max achieved at 90 W by the Tibetans was lower than that of the lowland migrators. It was concluded that, at HA, the lowlanders regained much of the aerobic capacity which they had lost initially. However, they did not attain the same gross mechanical efficiency as the Tibetans, who seemed to be at an advantage in respect of work at HA.

A Giardia duodenalis gene encoding a protein with multiple repeats of a toxin homologue

A gene, CRP136, from the intestinal protozoan parasite Giardia duodenalis, expressed at a high level in a metronidazole-resistant line, encodes a 136 kDa protein with 23 copies of a 40 amino acid repeat. The protein is cysteine-rich and has the typical membrane-spanning region and CXXC amino acid motifs of a family of Giardia cysteine-rich surface proteins (CRSPs). The repeat unit in CRP136, shares 57% homology with the gene encoding the precursor of the sarafotoxins, a group of snake toxins from the burrowing adder known to cause symptoms similar to those of humans acutely infected with Giardia. The sarafotoxins are low molecular weight sulphydryl cross-linked peptides which are proteolytically cleaved from a precursor polyprotein. CRP136 has homology over the entire length of the sarafotoxin precursor, and the repeats are of the same length. Thus CRP136 represents the first evidence for a potential Giardia toxin. The genomic copy number of CRP136 appears to be the same in both the parent and drug-resistant lines and expression of this gene, and at least one other, is associated with a conserved partial duplication, but not amplification, of one chromosome.

Peroxisomal membrane protein PMP68 of mouse liver: cloning of a cDNA encompassing the nucleotide binding fold and epitope mapping of monoclonal antibodies to the expressed protein

We have isolated and sequenced a cDNA which encodes 376 amino acids toward the carboxy-terminus, and encompassing the putative nucleotide binding fold, of PMP68 (mouse liver peroxisomal integral membrane protein of 68 kDa) the major integral membrane protein of mouse liver peroxisomes. The protein sequence predicted from this cDNA shows 97.9% amino acid identity to this same region of rat liver PMP70, a member of the ATP-binding cassette protein superfamily (K. Kamijo, S. Taketani, S. Yokota, T. Osumi, and T. Hashimoto, 1990, J. Biol. Chem. 265, 4534-4540). The section of the cDNA encoding the hydrophilic and putative cytoplasmic domain of PMP68 was expressed as a recombinant fusion protein in bacteria. Two monoclonal antibodies raised against this protein have been epitope-mapped to peptides generated by cyanogen bromide cleavage of the fusion protein. Antibody 1A4 recognizes a peptide whose sequence contains the first motif of the putative nucleotide binding fold of PMP68, and antibody 8F11 recognizes a carboxy-terminal peptide which includes the second motif of this nucleotide binding fold. These antibodies are expected to be useful in the elucidation of the biological function of this putative membrane transporter.

Echographic evaluation of primary cysts of the iris pigment epithelium

PURPOSE

Primary cysts of the iris pigment epithelium frequently appear to be focal elevations of the peripheral iris. To differentiate them from other anterior segment tumors requires the ability to assess the distribution, tissue characteristics, and progression of such lesions, which we accomplished by using anterior segment echography.

METHODS

We reviewed the medical records of 49 consecutive patients referred to the Doheny Eye Institute for echographic evaluation of focal bulging of the peripheral iris. Echography of the anterior segment was performed on each patient by using an immersion technique. Clinical examination was also performed on 20 (41%) patients at the time of initial examination.

RESULTS

We identified 52 iris pigment epithelial cysts in 52 eyes of the 49 patients studied. All lesions were single, localized to the posterior iris surface, and demonstrated a well-circumscribed, echolucent structure on B-scan echography. Average maximal sagittal thickness was 1.6 +/- 0.4 mm. Cysts were most frequently located in the inferotemporal quadrant (31%). Minimal increase in size or regression of lesions was noted in the nine patients (ten eyes) for whom follow-up echographic examinations were available.

CONCLUSIONS

Primary iris pigment epithelial cysts possess characteristic features with regard to location, size, and internal structure, which can be accurately documented with echography. Clinically evident lesions tend to be between 1 and 4 mm in maximum sagittal thickness, conform to the contour of posterior chamber structures without distortion, produce anterior bulging of the peripheral iris, are preferentially located in the inferotemporal quadrant, and demonstrate limited potential for growth.

Effect of organic modifier concentrations on electrokinetic migrations in micellar electrokinetic chromatography

The effect of low concentrations of organic modifiers on the electroosmotic mobility, mueo, and electrophoretic mobility of the micelle, muep, mc, in micellar electrokinetic chromatography (MEKC) with sodium dodecyl sulfate (SDS) solutions was investigated. The results showed that mueo was mainly influenced by the viscosity of the running solution. A linear relationship between mueo and the concentration of the organic modifier was found in MEKC. A newly defined parameter, the mobility ratio, Rm, mc, which is the ratio of the electrophoretic mobility of the micelle to the electroosmotic mobility, and which characterizes the surface charge density of the micelle in MEKC system with organic modifiers, was introduced. A linear relationship between Rm, mc and the organic modifier concentration was observed. The parameter Rm, mc was found to be useful to investigate the changes in the micellar phase with the addition of organic modifier. The measured muep, mc values showed different and interesting characteristics among different organic modifiers.

[Inclusion compounds of jiuxin oil with beta-cyclodextrin]

The inclusion compounds of Jiuxin Oil with beta-cyclodextrin were prepared. The influence of temperature, ratio of host and guest molecules, stirring time on inclusion were observed. The quantitative determination was performed by gas chromatography. Inclusion compounds of Jiuxin Oil were confirmed by differential scanning calorimetry and powder X-ray diffractometry.

Enhanced type 2 and diminished type 1 cytokines in neonatal tolerance

We examined the cytokine profiles associated with tolerance and rejection using the mouse model of neonatal tolerance. BALB/c mice primed with CAF1 splenocytes during the neonatal stage showed increased A/J skin graft survival of > 60 days and failed to develop anti-A/J cytotoxic responses, but rejected third-party C57BL/6 grafts. Lymph node cells that drained A/J grafts on neonatal-primed mice produced allospecific immune cytokine responses characterized by high IL-4 and low IFN-gamma levels. In contrast, lymph node cells that drained either rejected third-party grafts or rejected A/J grafts placed on adult controls produced less IL-4 and more IFN-gamma. Tolerogen-specific immune responses from neonatal-primed mice made up to 100 times higher IL-4 to IFN-gamma ratios than did controls. Alloantigen priming during the immediate neonatal stage induced constitutive expression of IL-4 mRNA in the spleen without IFN-gamma mRNA, whereas alloantigen stimulation during adulthood induced the opposite pattern. IL-4 production from neonatal primed mice was confined to the CD4 population. The altered cytokine profile of enhanced IL-4/IFN-gamma in neonatal primed mice persisted for up to 12 weeks after priming in in vitro secondary MLR assays, which suggests that the initial timing of antigen stimulation critically influenced CD4 maturation. The results support a model of immunoredirection as a mechanism of tolerance and provide rationale for examining the therapeutic use of cytokines in transplantation.

Experimental topical tetracycline-induced neuritis in the rat

PURPOSE

Recent studies have reported that tetracycline may induce chronic inflammatory responses in the adjacent soft tissues. The purpose of the present study was to determine if dry, powdered tetracycline evoked an inflammatory response in nerve tissue.

MATERIALS AND METHODS

Twenty male Sprague-Dawley rats were anesthetized and bilateral mental nerves were exposed. Half of the 40 nerves were intentionally injured by removing the epineurium, and the remaining nerves were uninjured. In a prospective, randomized, double-blind manner, equal volumes of color-matched, precoded tetracycline powder or Gelfoam (Upjohn, Kalamazoo, MI) powder control was placed in intimate contact with the nerves and sealed in polyethylene tubes. Forty-five days later the animals were killed and 5-micron sections of the nerves were prepared for histologic examination. The presence of epineurium, fascicular number, and fascicular area were measured. An inflammatory response in nerve tissue and the intrafascicular and epifascicular inflammatory index was measured by counting darkly stained nuclei with a Jandel Video Analysis System (Jandel Scientific, Corte Madera, CA).

RESULTS

Experimental injury (ie, epineurectomy) of nerves resulted in a statistically significant increase in fascicular number (P = .034), but not in fascicular area. For the intrafascicular inflammatory index, there was a significant main effect for drug (P = .002) and injury (P = .002). Experimental injury in both Gelfoam control and tetracycline grouped nerves resulted in an increase in intrafascicular inflammation. There was no significant increase in intrafascicular inflammation in either Gelfoam control or tetracycline grouped nerves when the epineurium was intact. The combination of both tetracycline and epineurectomy resulted in the largest increase in intrafascicular inflammation found among the groups studied. For epifascicular inflammatory index, there was a significant main effect for drug (P = .003) and injury (P = .001) that mirrored the intrafascicular inflammatory pattern.

CONCLUSION

The results of the present study suggest that dry, powdered tetracycline accentuates the inflammatory response in intrafascicular and epifascicular nerve tissue following epineurectomy. The maintenance of epineurium inhibited the inflammatory response in intrafascicular and epifascicular nerve tissues. Gel-foam was an inert material when placed against exposed nerve tissue. These findings suggest that tetracycline should not be placed in extraction sockets when injury of the inferior alveolar and/or lingual nerves are present.

Orthogonal array design as a chemometric method for the optimization of analytical procedures. Part 5. Three-level design and its application in microwave dissolution of biological samples

The theory and methodology of a three-level orthogonal array design as a chemometric method for the optimization of analytical procedures were developed. In the theoretical section, firstly, the matrix of a three-level orthogonal array design is described and orthogonality is proved by a quadratic regression model. Next, the assignment of experiments in a three-level orthogonal array design and the use of the triangular table associated with the corresponding orthogonal array matrix are illustrated, followed by the data analysis strategy, in which significance of the different factor effects is quantitatively evaluated by the analysis of variance (ANOVA) technique and the percentage contribution method. Then, a quadratic regression equation representing the response surface is established to estimate each factor that has a significant influence. Finally, on the basis of the quadratic regression equation established, the derivative algorithm is used to find the optimum value for each variable considered. In the application section, microwave dissolution for the determination of selenium in biological samples by hydride generation atomic absorption spectrometry is employed, as a practical example, to demonstrate the application of the proposed three-level orthogonal array design in analytical chemistry.

Effects of chorda-lingual nerve injury and repair on human taste

Citric acid detection threshold and magnitude response were measured on the anterior tongue in 10 patients with unilateral chorda-lingual nerve transections before and after repair. Fungiform taste buds were analysed by videomicroscopy. Preliminary data suggests that humans can regenerate fungiform taste buds and recover some taste sensitivity after repair.

Effects of linear polyacrylamide concentrations and applied voltages on the separation of oligonucleotides and DNA sequencing fragments by capillary electrophoresis

Oligonucleotides and DNA sequencing fragments have been separated by capillary electrophoresis employing linear polyacrylamide (LPA) as a sieving matrix. A commercially available apparatus equipped with a laser-induced fluorescence (LIF) detection system has been utilized, but the capillary cartridge has been modified to position the capillaries without coiling. The performance of the separation, the relationship between resolution and analysis time, has been examined using poly(dT)16-500 by changing LPA concentration, capillary length, and electric field strength. It was found that, for large DNA fragments, the migration time interval between bands decreases linearly as DNA fragment size increases. This implies that there exists a maximum base number to be resolved, irrespective of the band width (we named the maximum base number Nmax). The higher value of Nmax is obtained when the applied field strength is lower, but this accompanies longer analysis time with a concomitant increase in band width. Simple experimental equations have been proposed to calculate resolution and migration times of DNA fragments separated in our system at given electrophoretic conditions. Using 9% T LPA and an electric field strength of 100 V/cm, single-base resolution of M13mp10 DNA fragments up to 520 nucleotides has been obtained.

Transcription of a human neurotropic virus promoter in glial cells: effect of YB-1 on expression of the JC virus late gene

We have isolated a partial recombinant cDNA clone from a HeLa expression library which encodes a protein capable of binding to the central region of the human neurotropic JC virus (JCV) enhancer/promoter, termed the B region. Sequence analysis revealed a complete homology of the partial cDNA clone to the N-terminal region, of a previously described DNA-binding protein, termed YB-1. Band shift analyses have indicated that the bacterially produced YB-1 interacts specifically with the double-stranded B oligonucleotide as well as the corresponding single-stranded DNA fragment representing the early promoter sequence. Further analysis indicated that the YB-1 protein binds specifically to the C/T-rich sequence of the B domain, which is located in close proximity to the TATA box within the virus enhancer/promoter. Results from cotransfection experiments demonstrated that the full-length (YB-1) but not the partial cDNA enhances expression of the JCV late (JCVL) promoter in glial cells. Cointroduction into glial cells of a recombinant expressing the YB-1 and JCVL deletion mutants indicated that removal of the C/T-rich sequence of the B domain reduces the level of activation of the virus promoter by YB-1. Further cotransfection experiments revealed that the virus transactivating protein T antigen appears to diminish the ability of YB-1 to activate JCVL gene expression. RNA studies indicated that YB-1 is expressed in several cell types and tissues. Examination of YB-1 RNA from mouse brain at various stages of development revealed high levels of YB-1 RNA at early stages of development and lower levels at all subsequent developmental stages.

[Changes in serum lipoprotein cholesterol in rabbit model of calcium bilirubinate cholangiolithiasis]

The lithogenic process of cholangiolithasis is still not understood clearly. In this study, several serum lipoprotein cholesterol, the bile BA level, etc. in the rabbit model of calcium bilirubinate cholangiolithiasis was examined. The main results included: (1) The concentrations of HDL-ch and HDL2-ch in the serum decreased in all the experimental groups (P < 0.01; P < 0.05), except HDL-ch in the BO 1W group (P > 0.05) compared with the control group. The concentrations of HDL2-ch in the BOI 1W and the BOI 6W groups were lower than those in the BO 1W and the BO 6W groups respectively (P < 0.05); the both concentrations of Fch and HDL3-ch in the BOI and the BO groups were much higher than those in the control group (P < 0.01). (2) The bile T-BA level was lower in the both BOI groups than that in the control group (P < 0.05). It began to decrease in the BO group during the first week, but it was not significant in statistical difference (P > 0.05). During the 6th week the level of the bile acid (BA) was much lower than that in the control group (P < 0.05). According to the above results, it may be concluded that in the formation of calcium bilirubinate gallstones, caused by the biliary obstruction and infection, there is a disorder in the lipoprotein metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of paraquat toxicity in suspensions of alveolar type II cells by paraquat-specific antibodies

1. The herbicide, paraquat, is accumulated by the energy-dependent polyamine uptake pathway of alveolar type II cells. There it undergoes redox cycling that results in an amplified production of toxic reactive oxygen species and depletion of NADPH and other reducing equivalents. These processes account for the lung being the major target organ for paraquat toxicity. 2. We postulated that paraquat-specific antibodies would inhibit the uptake of the herbicide by type II cells and prevent its toxicity. Accordingly, we examined the effects of paraquat-specific monoclonal antibodies and Fab fragments on the uptake, efflux and cytotoxicity of 50 microM paraquat in suspensions of alveolar type II cells isolated from the rat. 3. The uptake of paraquat was linear over 40 min. Over this time, the uptake rate was inhibited significantly (% inhibition, 73-89) by IgG (25 or 50 microM) or Fab fragments (50 or 100 microM). 4. The apparent efflux rate of paraquat, studied over 16 h, was increased significantly from 0.12 h-1 for the control cells in medium to 0.17 h-1 by paraquat-specific Fab fragments but was unaffected by the specific IgG. 5. Cytotoxicity was determined by measuring the release of 51Cr from the cells. The cytotoxicity of 50 microM paraquat was decreased significantly (percent decrease, 56-80%) in the presence of specific antibodies. 6. These studies in vitro suggest some potential for immunotherapy in selected cases of paraquat poisoning.

Physical map of a 2 Mb chromosome of the intestinal protozoan parasite Giardia duodenalis

The protozoan parasite, Giardia duodenalis, is regarded as the most primitive eukaryote. The two apparently identical nuclei presumably carry the same chromosomes but the number of different chromosomes in the organism is unknown. A genome map of G. duodenalis is required to resolve this issue and mapping studies were initiated using chromosome 5. This chromosome was estimated to be approximately 2 Mb when Giardia chromosomes were separated by contour-clamped homogeneous electric field gel electrophoresis. A plasmid library of chromosome 5-specific DNA sequences was constructed from gel-extracted chromosome 5 and selected probes were used as markers to identify NotI DNA segments derived from chromosome 5. Fifty-nine unique copy markers were used to identify thirteen NotI segments which ranged in size from 47 kb to 400 kb. The sum of the NotI segments was 1.78 Mb which indicated that most, if not all, of the chromosome was accounted for and that chromosome band 5 of the cloned line WB-1B, used in this study comprised only one chromosome type. The NotI segments were ordered on the map by comparison of hybridization patterns of the markers with partial NotI cleavages of whole chromosomes. Chromosome rearrangements occur readily in Giardia, and in two drug-resistant lines selected for resistance to different drugs, partial conservative duplications of chromosome 5 were observed in addition to the original, full length chromosome 5. Both duplications retained the central region of chromosome 5 but were deleted at different termini resulting in one duplication of 1.5 Mb and the other of 1.3 Mb.(ABSTRACT TRUNCATED AT 250 WORDS)

Separation and identification of proteins obtained from Agkistrodon acutus snake venom by capillary zone electrophoresis and laser desorption/ionization mass monitoring

Fractions of seven protein principles with fibrinolytic or thrombin-like activities obtained from Agkistrodon acutus snake venom purified by two steps of normal pressure chromatography were separated further by capillary zone electrophoresis (CZE). Mass determination for these fractions were achieved by performing laser desorption/ionization mass monitoring (LDIM). The comparative study between CZE and LDIM on the separation of these fractions was made.

Retinoblastoma protein expression is frequently altered in chronic lymphocytic leukemia

The detection of abnormalities at the retinoblastoma (RB) locus by cytogenetics, Southern blot, and fluorescence in situ hybridization studies suggests that the RB gene has a role in chronic lymphocytic leukemia (CLL). To further study this role, we determined the level of RB protein present in the mononuclear cell fraction derived from peripheral blood or bone marrow samples from 74 patients with CLL, by Western blotting. Compared to similarly prepared samples from the peripheral blood of normal individuals, the level of RB in CLL cells was less than normal in 42% of patients, equal to normal in 22% of patients, and in excess of normal in 36% of patients. Regardless of whether the source of the sample was blood or marrow or if the patients were untreated or previously treated, similar rates of low, normal, and elevated RB levels were observed. RB protein in the CLL patient samples was never phosphorylated. RB levels showed no correlation with the lymphocyte doubling time or with proliferating cell nuclear antigen levels. Low RB levels could arise from genetic alterations of the RB gene or altered regulation of expression. To determine which was occurring, we stimulated the cells from 27 CLL patients in culture with either phytohemagglutinin or pokeweed mitogen in an attempt to induce RB expression and phosphorylation. Among patients with low levels of RB, expression was induced in 46% (6 of 13), and phosphorylation of RB was seen in 31% (4 of 13). Increased expression of phosphorylated RB was induced in 80% (4 of 5) of patients with normal levels of RB and in 78% (7 of 9) of patients with high levels of RB. This study demonstrates that absent RB expression occurs commonly in patients with CLL. Intrinsic abnormalities of the RB gene may be present in those patients with low levels of RB that could not be stimulated by mitogens, while regulatory abnormalities located in trans to the RB gene may occur in the other half. Given the importance that RB levels play in other cancers, the prognostic implication of low RB levels should be studied in CLL.

Phototoxicity of lumidoxycycline

Doxycycline (DOTC) is a photosensitizing drug whose mechanism of phototoxicity is complicated by the large variety of stable photoproducts formed. To assess the role of a DOTC photoproduct, lumidoxycycline (LuDOTC), in the photosensitization mechanism of DOTC, MGH-U1 human bladder carcinoma cells were treated in vitro with either DOTC or LuDOTC, and irradiated with the 351-nm emission of an argon-ion laser. Both DOTC and LuDOTC were phototoxic and caused radiant-exposure-dependent inhibition of cellular incorporation of tritiated thymidine. On an absorbed-photon basis, DOTC was about five times as phototoxic as LuDOTC. Cellular uptake of DOTC was about five times as great as that of LuDOTC. Epifluorescence microscopy showed localization of LuDOTC predominantly within cellular membranes, particularly of mitochondria, as well as a low level of LuDOTC fluorescence diffusely within the cytoplasm. Epifluorescence microscopy of cells labeled with the mitochondrial probe, rhodamine 123, showed mitochondrial fragmentation and altered mitochondrial membrane integrity after LuDOTC photosensitization; these effects depended on radiant exposure and were partially reversible by 24 h after irradiation. For both DOTC and LuDOTC, phototoxicity was increased by irradiation in the presence of deuterium oxide and decreased in the presence of sodium azide, effects consistent with an important mechanistic role for singlet oxygen, O2(1 delta g), in the injury. In solution, LuDOTC and DOTC had similar quantum yields for generation of O2(1 delta g) as measured by time-resolved spectroscopy and by O2(1 delta g) trapping. LuDOTC was photostable in solution, but DOTC underwent significant photodegradation. These data demonstrate that DOTC photo-products such as LuDOTC have significant photobiologic activity and may play an important role in the phototoxicity mechanism of DOTC.

Polyclonal amanitin-specific antibodies: production and cytoprotective properties in vitro

The amanitins found in several mushroom species are responsible for many deaths every year. Based on its successful application to cardiac glycoside overdose, immunotherapy could be applicable to amanitin toxicity. Therefore, we produced polyclonal amanitin antibodies by immunizing rabbits with a novel conjugate of alpha-amanitin. Purified antibodies had an average association constant for alpha-amanitin of 1.3 x 10(9) M-1. A partially protective effect of the antibodies against amanitin toxicity in vitro in Chang cells was evident at a molar ratio of antibody binding sites to alpha-amanitin of 4:1. Together with reported studies in vivo, these investigations indicate the potential of immunotherapy for amanitin poisoning.

High performance liquid chromatographic determination of individual bile acids in serum for automatic diagnosis of various liver and biliary diseases

A reversed phase high performance liquid chromatographic method for the high sensitivity determination of individual bile acids in serum using a C18 column with a ternary solvent system combined with fluorometric techniques using immobilized enzymes is described. A computer-assisted diagnosis system using pattern recognition was developed to assist the clinical diagnosis of various liver and biliary diseases. A total consistency rate of 95% can be reached using this system.

Free-solution capillary electrophoretic separation of small hydrophilic peptides

Small hydrophilic peptides differing in only one glycine amino acid group have been successfully separated by free-solution capillary electrophoresis (FSCE) using phosphate buffer at acid pH. The effects of column temperature and operating current on the migration times of these small peptides have been investigated. The results from FSCE have been compared with those from reversed phase high performance liquid chromatography.

How frequent are hepatitis B virus markers in adult patients with glomerular diseases in a low endemic country? A French study from Paris and Saint-Brieuc

In order to appreciate the frequency of hepatitis B virus (HBV) infection in patients with glomerular diseases in France, a low endemic country, we reviewed the series of patients biopsied in the years 1983-1989 in 2 departments of nephrology differing by the characteristics of the population. In Saint-Brieuc, where the population is almost exclusively Caucasian, with nearly no immigrant, HBsAg was not detected in any of the 86 patients. In Paris, a large number of patients come from highly or intermediately endemic regions. HBsAg was detected in 3 of 209 patients, 2 of the 75 patients with membranous nephropathy and 1 of the 32 patients with minimal-change nephrotic syndrome. These patients came from Africa and Asia. Therefore, in low endemic countries, the role of HBV infection in the etiology of glomerulonephritis is minimal. But, because of the late severity of the disease, screening remains essential in patients belonging to the high-risk groups.

Competition between paraquat and putrescine for uptake by suspensions of rat alveolar type II cells

Paraquat and the structurally similar polyamines, such as putrescine and spermidine, are accumulated actively and selectively by the alveolar type II cells via the polyamine uptake system. We report the uptake kinetics of paraquat and putrescine and their mutual inhibition in freshly isolated rat type II cell suspensions. The uptake of paraquat by type II cells exhibited saturation kinetics and could be inhibited in a concentration-dependent manner by putrescine. By applying enzyme kinetic analysis to our experimental data it was demonstrated that the uptake of paraquat or putrescine is inhibited in a partially competitive manner by the respective inhibitor. Thus, we postulate that the polyamine uptake pathway in type II cells for paraquat and putrescine has two separate sites, one for each substrate, and that binding of one leads to a conformational change in the other.

The retention behaviour of conjugated bile acids in reversed phase high performance liquid chromatography

The retention behaviour of conjugated bile acids has been studied in a reversed phase high performance liquid chromatographic (RP-HPLC) system by using the mixture of methanol and aqueous phosphate buffer as the mobile phase. The retentions of the conjugates in RP-HPLC have been found to be mainly controlled by the glycine and taurine groups. The selectivity between five different glycine and taurine conjugated bile acids is a constant in RP-HPLC. This selectivity has been used for peak identification in the practical separation of conjugated bile acids.

Induction of the major integral membrane protein of mouse liver peroxisomes by peroxisome proliferators

Peroxisome proliferators are known to increase the volume of the peroxisomal compartment in rodent liver. We have examined the induction of the major integral membrane protein of mouse liver peroxisomes (PMP68) by a number of these agents, and compared this with their effect on the peroxisomal bifunctional protein (PBP), an enzyme of the beta-oxidation pathway which is located in the peroxisome matrix. Dietary clofibrate, di-2-(ethylhexyl)phthalate and Wy-14,643, three structurally unrelated proliferators, all increased the mRNA and protein content of PMP68 approx. 2-fold, whereas PBP was induced 8-13-fold. The kinetics and sequence of induction of PMP68 and PBP following a single dose of Wy-14,643 were compared and shown to be similar, and the effects were reversible. Another proliferator, BM 15766, caused maximal induction of PMP68 but only a low induction of PBP; further PBP induction was achieved by the administration of BM 15766 in combination with Wy-14,643. Similarly, BM 15766 and Wy-14,643 increased transcription of the PMP68 gene in vitro, whereas PBP gene transcription was increased by Wy-14,643 but not by BM 15766. Thus peroxisome proliferators enhance the expression of the genes for both the membrane protein PMP68 and the matrix protein PBP, but the regulation of this expression appears to be mediated by different mechanisms.

Azidowarfarin photoaffinity probes of purified rat liver cytochrome P4501A1

Substrate specificity differences between various forms of cytochrome P450 (P450) are governed by substrate binding site amino acid residue differences. To determine the identities of these residues, four analogs of warfarin, a thoroughly investigated anticoagulant drug which is regio- and stereoselectively metabolized by many P450s, have been synthesized as photoaffinity probes. The probes 4'-, 6-, 7-, and 8-azidowarfarin were readily photolyzed in neutral solution by 254-nm light, with half-lives of less than 15 s. When the azidowarfarins were photolyzed in the presence of beta-naphthoflavone-inducible P4501A1 (2.5 microM) at -196 degrees C and the P450 was subsequently reconstituted for warfarin metabolism, 50% inactivation was achieved with 160 microM 4'-azidowarfarin, 64 microM 6-azidowarfarin, 127 microM 7-azidowarfarin, and 29 microM 8-azidowarfarin. This inactivation is irreversible. When these concentrations of the azidowarfarins were photolyzed prior to addition to P4501A1, less inhibition of P450 activity was detected and the inhibition was reversible. The CO-ferrous P450 spectrum of P4501A1 at 448 nm was diminished when photoactivated azidowarfarins bound to and inactivated the enzyme, with essentially no formation of P420 except in the case of 4'-azidowarfarin. The inactivation of P4501A1 by photoactivated 4'-azidowarfarin was prevented by 50% by 1.2 mM R-warfarin or 0.3 mM 4'-nitrowarfarin, consistent with the latter being a better P4501A1 substrate than R-warfarin. The photoinactivation of P4501A1 by each of the azidowarfarins was prevented to variable extents by R-warfarin or by 4'-, 6-, 7-, or 8-nitrowarfarin. Taken together these results demonstrate that all four azidowarfarins are potentially useful photoaffinity probes of the substrate binding site amino acid residues of P450s.

Worldwide perspective of hepatitis B-associated glomerulonephritis in the 80s

Chronic HBsAg carriers may develop glomerulonephritis (GN). Besides membranous GN (MGN), which seems a well established association, membranoproliferative GN (MPGN) or proliferative GN are also encountered in these patients. It is clear that the variations in the incidence of hepatitis B virus (HBV) GN may be real or related to a more or less vigorous search for HBV in the different nephrologic centers. However, the frequency of HBV GN in a country correlates with the underlying prevalence of HBV infection in the general population. Geographic patterns of HBV prevalence vary greatly from areas of low endemicity where less than 1% of adults are chronic carriers to areas of intermediate and high endemicity where between 2 and 15% of adults are chronic carriers. The most important factor affecting prevalence is age of HBV infection. The probability of becoming a chronic carrier is greater following infection during infancy and early childhood. The rarity of HBV GN in the U.S. and in western Europe probably reflects the rarity of HBV infection, especially in children. The frequency of HBV GN is high in Asian or Black children. It is possible to hope that, with the extensive immunization in countries of high endemicity, the frequency of HBV GN will diminish. In the U.S. and in Europe, patients with HBV GN frequently belong to high risk groups for HBV infection. In these countries, the increase in the percentage of HBV infection due to sexual transmission or linked with drug abuse may lead to an increase in the percentage of adult patients with HBV GN.

Light-chain composition of serum IgA1 and in vitro IgA1 production in IgA nephropathy

A predominant expression of IgA1 in mesangial deposits, serum, and bone marrow culture supernatants has been shown in IgA nephropathy (IgAN). Furthermore an excess of lambda light chains in both mesangial deposits and serum IgA has been observed. However, the origin of mesangial IgA remains controversial. In the present study, we have examined the IgA1 light chain type in IgAN. Total IgA1, IgA1 kappa and IgA1 lambda were measured by ELISA in serum and culture supernatants from spontaneous and pokeweed-mitogen (PWM)-stimulated peripheral blood mononuclear cells (PBMC). We observed an increase in IgA and IgA1 serum concentrations in IgA nephropathy patients, with a ratio of serum IgA1 to total serum IgA identical between patients and controls. The concentration of serum IgA kappa did not differ between patients and controls but patients had a significantly higher concentration of serum IgA lambda. The IgA1 kappa to IgA1 lambda ratio was 1.06 +/- 0.42 in IgAN patients versus 1.55 +/- 0.36 in controls (P less than 0.01). By contrast, the concentrations of IgA1 kappa and IgA1 lambda in PBMC culture supernatants, both spontaneous and PWM-stimulated, were identical in patients and controls. Therefore, there is a specific increase in IgA1 lambda in patients' sera. This contrasts with the normal IgA1 production by PBMC, which are derived from mucosal-associated lymphoid tissues. This suggests that IgA isotypic deregulation is confined to the bone marrow compartment and is not a generalised defect of the IgA system.

Effect of central obesity on regulation of carbohydrate metabolism in obese patients with varying degrees of glucose tolerance

It has been proposed that central obesity, by virtue of the enhanced lipolytic activity of abdominal adipose tissue, leads to higher plasma FFA concentrations, which, in turn, decrease both hepatic removal of insulin and insulin-stimulated glucose uptake by peripheral tissues. In short, the predicted consequences of abdominal obesity are elevations in circulating FFA and insulin levels as well as insulin resistance. The goal of this study was to evaluate the relationships predicted by the overall hypothesis; this study was carried out in 31 obese females, defined as having normal glucose tolerance (n = 12), impaired glucose tolerance (n = 8), or noninsulin-dependent diabetes mellitus (n = 11). Abdominal obesity was estimated by determining the ratio of waist to hip girth, fasting and postprandial plasma FFA and insulin concentrations were measured at hourly intervals from 0800-1600 h, and insulin-stimulated glucose disposal was quantified by the euglycemic hyperinsulinemic clamp technique. The first step in the postulated sequence of events to be tested was that the greater the WHR, the higher the total integrated plasma FFA response. The correlation coefficient between these two variables was 0.29, indicating that the results did not support the prediction. Furthermore, we could not demonstrate any relationship between the magnitude of the plasma FFA and insulin responses (r = 0.20; P = NS). However, there was a modest inverse relationship between height of circulating plasma insulin concentration and a decrease in insulin-stimulated glucose uptake (r = -0.43; P less than 0.03) in the group as a whole. On the other hand, when the three groups were analyzed individually, a significant inverse relationship was only seen in the control group (r = -0.67), and a direct relationship was actually seen in patients with impaired glucose tolerance (r = 0.88). Furthermore, when the mean responses for the variables in each of the three groups were compared, it was apparent that the postulated relationships between abdominal obesity, plasma FFA concentration, and insulin secretion and action were not present. Thus, the data presented do not support the hypothesis that differences in the degree of central obesity play an important role in regulation of plasma concentrations of either FFA or insulin or in modulation of insulin-stimulated glucose uptake in the patients we studied.

[Effect of phospholipase A2 on pancreatic parenchymal necrosis in acute pancreatitis in rats]

The effect and mechanism of phospholipase A2 (PLA2) on pancreatic parenchymal necrosis in acute pancreatitis (AP) in rats were studied. Normal saline (NS), PLA2, phosphatidylcholine (PC), and PLA2 mixed PC were respectively injected into the biliopancreatic duct of the rat. The mixture of PLA2 and PC was found to result in necrotizing AP in the rat in 12 hours after injection of the reagent. The lysophosphatidylcholine (LPC) percentage in the amount of PC and LPC and the extent of pancreatic necrosis in this group increased much more significantly than those in other three groups (over about 4 and 15 times). There is evidently positive correlation (r = 0.9001, P less than 0.01) between LPC percentage and necrosis extent. The intraductal injection of PLA2, as well as NS or PC, failed to induce severe morphological changes in the pancreases. These results suggest that PC in bile is necessary in the pathogenesis of biliary pancreatitis and that LPC originated from bile PC by PLA2 may be the initiator in pancreatic parenchymal necrosis in AP.

Rhodamine 123 phototoxicity in laser-irradiated MGH-U1 human carcinoma cells studied in vitro by electron microscopy and confocal laser scanning microscopy

Rhodamine 123 (R123) is a permeant, cationic, fluorescent dye that localizes preferentially within mitochondria of living carcinoma cells. MGH-U1 human bladder carcinoma cells incubated in vitro with 10 microM R123 for 30 min and then irradiated at 514.5 nm with an argon ion laser underwent selective, phototoxic injury to mitochondria. Ultrastructurally, treatment with R123 plus irradiation with 10 J/cm2 caused selective, progressive mitochondrial alterations consisting of disruption of cristae, vacuolization, swelling, increasing numbers of ring-shaped and angulated mitochondria at 4 to 8 h after irradiation, and obliteration of many mitochondria at 24 to 48 h. Confocal laser scanning microscopy after treatment with R123 plus irradiation with 10 to 30 J/cm2 demonstrated altered uptake and localization of subsequently administered R123, accompanied by striking mitochondrial fragmentation. Irradiation caused a dose-dependent depletion of extractable R123, due to a photosensitized efflux that began immediately and progressed by 4 h after irradiation with 10 to 30 J/cm2; further uptake after reincubation in the presence of R123 was also quantitatively impaired in cells previously irradiated with 30 J/cm2.