Improved brain metabolism with fructose 1-6 diphosphate during insulin-induced hypoglycemic coma

The effect of fructose 1-6 diphosphate (FDP) on brain metabolism and brain function was investigated in hypoglycemic rabbits. The electroencephalogram and differences in oxygen content of arterial and cerebral venous blood were used as indicators for brain metabolic activity. Hypoglycemic coma was induced and maintained for 1 hour by insulin administration. At the onset of isoelectric EEG, six rabbits were treated with FDP and five rabbits received 0.9% saline. The animals were killed by an overdose of barbiturate 60 minutes after hypoglycemic recovery with glucose. FDP-treated rabbits had lower arterial glucose concentration after 40 minutes of treatment (p less than .05) and a significantly greater difference between the oxygen content of arterial and venous blood after 40 minutes (p less than .01), and after 60 minutes (p less than .025) of FDP infusion than saline-treated rabbits. FDP-treated rabbits also had a lower cerebral glucose-oxygen index than did saline-treated rabbits (p less than .005, after 20 and 40 minutes of FDP infusion). FDP administration was followed by a return of EEG activity during hypoglycemia, whereas saline produced no such effect. After glucose infusion, EEG activity was improved in FDP-treated rabbits; in saline-treated rabbits, minimal or no EEG activity was observed. The data suggest the possibility that, at the doses given in this study, FDP is taken up and used as a metabolic substrate by the brain.

On the coordination of La3+ by phosphatidylserine

In a recent study by Bentz, J., D. Alford, J. Cohen, and N. Düzgünes (1988. Biophys. J. 53:593-607), La3+ was found to be more effective than Ca2+ in causing nonleaky fusion of phosphatidylserine vesicles. It was proposed that this difference in fusion efficiency may be due, in part, to a difference in coordination of the two cations. That is, Ca2+ was presumed to bind to the lipid phosphate, whereas La3+ was proposed to be coordinated by the serine carboxylate and amine. 31P and 13C NMR results presented here demonstrate that the lanthanides, Tb3+ and La3+, are coordinated by the phosphodiester and carboxylate moieties of phosphatidylserine. Tb3+-Phosphatidylserine optical experiments suggest that the serine amine does not coordinate the lanthanide below pH 10, at least not while the membrane has a net negative surface charge. Although these observations disagree with the structural details proposed by Bentz et al. (1988), they are not in conflict with their general fusion mechanism. The work presented here also demonstrates that La3+ affects the inner surface phosphodiesters differently than those on the outer surface of phosphatidylserine vesicles. The vesicles studied are of an intermediate size, having diameters on the order of 150-200 nm. The cation appears to have a more immediate effect on the packing of the crowded headgroups on the inner surface. Higher levels of bound La3+ on the outer surface may be required to induce the same changes in headgroup conformation.

Reverse transcriptase in a clinical strain of Escherichia coli: production of branched RNA-linked msDNA

Branched RNA-linked multicopy single-stranded DNA (msDNA) originally detected in myxobacteria has now been found in a clinical isolate of Escherichia coli. Although lacking homology in the primary structure, the E. coli msDNA is similar in secondary structure to the myxobacterial msDNA's, including the 2',5'-phosphodiester linkage between RNA and DNA. A chromosomal DNA fragment responsible for the production of msDNA was cloned in an E. coli K12 strain; its DNA sequence revealed an open reading frame (ORF) of 586 amino acid residues. The ORF shows sequence similarity with retroviral reverse transcriptases and ribonuclease H. Disruption of the ORF blocked msDNA production, indicating that this gene is essential for msDNA synthesis.

Clinical manifestations and diagnosis of acute pyrethroid poisoning

This article reviews 573 cases of acute pyrethroid poisoning reported in the Chinese medical literatures during 1983-1988. There were 325 cases of acute deltamethrin poisoning (occupational 158, accidental 167), 196 patients of acute fenvalerate poisoning (occupational 63, accidental 133, including 2 cases of ingestive fenvalerate-organophosphate mixture poisoning), 45 cases of acute cypermethrin poisoning (occupational 6, accidental 39) and 7 cases of other pyrethroid poisoning (occupational 2, accidental 5). The clinical manifestations have been reviewed and analysed. The diagnosis, gradation and differential diagnosis of occupational acute pyrethroid poisoning have been discussed.

Effects of pyrethroid insecticides on subjects engaged in packaging pyrethroids

A health survey was conducted on 199 workers engaged in dividing and packaging pyrethroids. The subjects were exposed to fenvalerate at 0.012-0.055 mg/m3 and deltamethrin at 0.005-0.012 mg/m3 in the air with simultaneous skin contact for 0.5-4.5 months. Burning sensations and tightness or numbness on the face appeared in two thirds of the subjects and one third had sniffs and sneezes. Abnormal facial sensations, dizziness, fatigue, and miliary red papules on the skin were more evident in summer than in winter. Neither abnormalities in other organs or systems nor symptoms or signs of acute pyrethroid poisoning were found by interviews, examinations, and laboratory tests. There was no significant difference in plasma levels of NA, cAMP, and cGMP between the examined subjects and the control group. The urine concentration of fenvalerate in the study group ranged from 1.02 to 18.6 micrograms/l; deltamethrin in the urine was present in trace amounts.

[In vivo metastasis of human tumor transplant in T and NK cell immune-deficient mice]

Beige-nude mice with combined T and NK cell deficiency were produced by introducing "nu" gene into the beige mice of C57BL/6 background. The beige-nude mice were characterized by morphological features, level and activity of the NK cell in spleen and peripheral blood. NK cell level of the beige-nude mice was higher than the beige mice and similar to the ordinary nude mice though its NK cell activity was markedly lower than the nude mice. Human lung adenocarcinoma (PAa) was transplanted subcutaneously to the beige-nude mice and nude mice of BALB/cA background. No metastasis was found in BALB/cA nude mice (0/7), while in beige-nude mice, spontaneous lymph node metastasis rate was 36.3% (4/11). It should be noted that the transplanted PAa metastasized to lungs, which had never been seen in BALB/cA nude mice in previous experiments. The increase of metastatic rate is correlated with the relative low NK cell activity of the beige-nude mice. Our observation is that the beige-nude mice could be a suitable experimental model for in vivo study on metastatic behavior of the human tumors.

[Different effects of selenium on proliferation of human lung adenocarcinoma cells and human embryonic lung diploid cells in vitro]

After treating human lung adenocarcinoma cells by Na2SeO3 (1 microgram/ml) for 24 hours, its mitotic index decreased by 50%. The reduction rate was directly proportional to selenite concentration (1-5 micrograms/ml). In the meantime, the labelling index, growth rate and progression of the cell cycle were also inhibited. In contrast to the above observation, there was no marked change in the cell count, mitotic index, labelling index and the average silver granule number in the human embryonic lung diploid cells treated by Na2SeO3 (1-5 micrograms/ml) for 1-3 days. When human embryonic lung diploid cells were mix-cultured with human lung adenocarcinoma cells in the presence of 5 micrograms/ml Na2SeO3 for 24 hours, the former maintained a normal morphology, while the lung cancer cells showed heavily vacuolated cytoplasms and distorted nuclei.

Chymopapain-induced hypersensitivity following chemonucleolysis

This study describes the changes in chymopapain-specific IgE antibody levels in patients following chemonucleolysis with Chymodiactin. Using the ChymoFAST method, chymopapain-specific IgE values were studied in 91 patients prior to and for 2 months post-Chymodiactin chemonucleolysis. A total of 8.8% (17/91) developed IgE levels greater than or equal to 0.06 IU/ml. Those patients with detectable IgE levels prior to chemonucleolysis were more likely than those with nondetectable preinjection levels (36.4% versus 4%) to develop chymopapain-specific IgE levels greater than or equal to 0.06 IU/ml.

A preoperative chymopapain sensitivity test for chemonucleolysis candidates

A fluorescence enzyme immunoassay (ChymoFAST test) for the quantitation of chymopapain-specific IgE antibody concentration in human serum is described. The IgE antibody is recognized as the major immunologic mediator for anaphylactic reactions. Serum chymopapain-specific IgE levels serve as an objective screening method for identifying patients most likely to tolerate chymopapain, thereby minimizing associated risks. Preoperative sera obtained from 11,658 chemonucleolysis candidates were tested, of which 0.94% (110/11,658) were found to be positive. Good predictive values for both positive and negative findings are evident based on 4776 postmarketing surveillances obtained from the surgeons.