[Inhibition of PKC and ERK1/2 in cultured rat vascular smooth muscle cells by angiotensin-(1-7)]

The present study was undertaken to investigate the effects of angiotensin-(1-7)[Ang-(1-7)] on the proliferation and expression of protein kinase C (PKC) and extracellular regulated protein kinases (ERK1/2) of vascular smooth muscle cells (VSMCs) by techniques of Western blot, 3H-thymidine (3H-TdR) and 3H-leucine (3H-Leu) incorporation. Ang II increased VSMC DNA and protein synthesis, and promoted protein expression of PKC-zeta and ERK1/2. In contrast, Ang-(1-7) not only inhibited PKC-zeta and ERK1/2 protein content, but also decreased Ang II mediated VSMC hyperplasia, as compared with the controls (P < 0.01 or P < 0.05). These results suggest that Ang-(1-7) may inhibit VSMC proliferation by influencing protein expression of PKC-zeta and ERK1/2.

[Effects of ischemia/reperfusion on the phosphotyrosine proteins contents in hippocampus]

AIM AND METHODS

The effects of three drugs including ketamine(KT), a noncompetitive antagonist of NMDA receptor (NR), nifedipine(ND), a voltage gated calcium channel (VGCC) antagonist and 6, 7dinitroquinoxaline -2, 3-dione(DNQX), a non-NMDA receptor antagonist on the contents of phospho-tyrosine proteins (p-tyr-pr) in the synaptosomal(P2), the crude membrane (P3), and the cytosolic (S3) fractions of hippocampus in forebrain ischemia of mongolian gerbils were studied.

RESULTS

(1) the contents of p-tyr-pr in all three fractions (P2, P3, S3) decreased 15 min after ischemia, but the contents of p-tyr-pr in S3 fraction decreased more obviously than the others did, With the increase of reperfusion time, the contents of p-tyr-pr in all of these fractions recovered gradually, but the p-tyr-pr in S3 fraction increased more rapidly among them, in the P2 fraction, the contents of p-tyr-pr increased slowly, but significantly and sustained longer during reperfusion when compared with that of P3 did. (2) The increase in p-tyr-pr contents induced by cerebral ischemia/reperfusion was partially antagonisted by KT and ND administration prior to cerebral ischemia, under these conditions, DNQX has no effect on it.

CONCLUSION

the increase of p-tyr-Pr contents induced by cerebral ischemia/reperfusion is related to NR channel and L-type VGCC, but not to non-NR channel.

Changes and mechanisms of protein-tyrosine kinase and protein-tyrosine phosphatase activities after brain ischemia/reperfusion

AIM

To study the changes and mechanisms of protein-tyrosine kinase (PTK) and protein-tyrosine phosphatase (PTP) activities in the hippocamal synaptosome following cerebral ischemia/reperfusion (I/R) in gerbil.

METHODS

Transient (15 min) global ischemia was produced by bilateral carotid artery occlusion. Total PTK and PTP activities were measured by [r-32P] incorporation and colorimetric analysis, respectively. Src and proline-rich tyrosine kinase2 (PYK2) activities were measured by immunoprecipitation and [r-32P] incorporation.

RESULTS

Total PTK activity increased significantly after I/R, but the PTP activity did not change. The Src activity was much higher than PYK2 activity in sham-operated controls. I/R mainly caused a pronounced increase in Src activity, but not PYK2 activity. The increase in Src activity had no relation to the expression of Src protein. Administration of ketamine (KT) or nifedipine (ND) 20 min before ischemia caused a decrease in total PTK and Src activities, and no change in the PYK2 and PTP activities.

CONCLUSION

The increase in PTK activity caused by I/R may be mainly due to the increase in Src activity. This increase in Src activity has no relation to the expression of Src protein. But it is related to the activation of NMDA (N-methyl-D-aspartate) receptor (NR) and L-type voltage-gated calcium channel (L-type VGCC). In other words, the increase in total PTK and Src activities induced by I/R may be mediated via NR and L-type VGCC. The PTP activity did not change during I/R.

Mechanisms of regulation of tyrosine phosphorylation of NMDA receptor subunit 2B after cerebral ischemia/reperfusion

AIM

To study the mechanisms of the regulation of the tyrosine phosphorylation of N-methyl-D-aspartate (NMDA) receptor subunit 2B(NR2B) in the gerbil hippocampal synaptosomes following ischemia/reperfusion (I/R).

METHODS

Transient (15 min) cerebral ischemia was produced by bilateral carotid artery occlusion procedure. The tyrosine phosphorylation of NR2B was analyzed by immunoprecipitation and immunoblot assay.

RESULTS

Transient forebrain ischemia for 15 min caused a marked decrease in the levels of tyrosine phosphorylation of many protein bands including 180 kDa protein. Transient ischemia followed by reperfusion induced rapid (within 15 min of reperfusion), and sustained (for at least 48 h) increase in the tyrosine phosphorylation of many protein bands including 180 kDa protein. Immunoprecipitation and immunoblot confirmed that NR2B is among the phosphorylated 180 kDa protein. Maximal phosphorylation of 180 kDa band corresponding to NR2B (1.8 fold relative to sham-operated controls) was reached at 6 h of reperfusion following 15 min of cerebral ischemia. But the level of protein expression of NR2B did not change. Administration of ketamine (KT), a non-competitive NMDA receptor antagonist, or nifedipine (ND), an L-type voltage gated calcium channel (L-type VGCC) blocker, 20 min before ischemia attenuated stimulation of the tyrosine phosphorylation of NR2B without affecting the level of protein expression of NR2B. Under these conditions, non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) had no effect on the level of tyrosine phosphorylation. Protein tyrosine phosphatase (PTP) inhibitor vanadate and protein tyrosine kinase (PTK) inhibitor genestein resulted in the increase and the decrease of the tyrosine phosphorylation of NR2B, respectively. Src coprecipitated with NR2B protein.

CONCLUSION

The increase of the tyrosine phosphorylation of NR2B induced by I/R has relation to NR and L-type VGCC; PTK and PTP participate in the regulation of the tyrosine phosphorylation of NR2B during I/R. Src that associates with NR2B may play an important role in the regulation of the tyrosine phosphorylation of NR2B during I/R.

Stage-specific expression of alpha1,2-fucosyltransferase and alpha1, 3-fucosyltransferase (FT) during mouse embryogenesis

Lex [Galbeta1-4(Fucalpha1-3)GlcNAc] and Ley [Fucalpha1-2Galbeta1-4(Fucalpha1-3)GlcNAc] are both stage-specific embryonic antigens. Lex is first detected on the blastomeres of the 8-cell stage embryo, which correlates with the onset of blastomere compaction. Ley is highly expressed on the surface of the blastocyst, which has been shown to be involved in blastocyst attachment in the mouse. In the present study, mouse alpha1,2-FT (also known as FUT1) and alpha1,3-FT (also known as Fuc-TIV), which were responsible for Lex and Ley formation, were examined in preimplantation stage embryos by reverse transcription-PCR and in situ hybridization. alpha1,3-FT mRNA was detected in all embryos of preimplantation stage, while alpha1,2-FT mRNA emerged in the later stage embryos from 8-cell to 16-cell to the blastocyst. These results indicated the expression of Ley was regulated by alpha1,2-FT. In situ hybridization showed that these two enzyme mRNAs were detected only in morula and blastocyst stage embryos. The alpha1,2-FT and alpha1, 3-FT mRNAs were located in both the inner cell mass and the trophoblast cells. 2-Cell and 4-cell embryos were isolated from the oviduct and cultured in vitro to the 8-cell, morula and blastocyst stage. The expression of alpha1,2-FT and alpha1,3-FT were observed in these embryos developed in vitro; immunohistochemical analysis also showed that Ley expression was positive. These results suggested the stage-specific expression of Ley on the embryos was synthesized by endogenous alpha1,2-FT and alpha1,3-FT rather than transfer from other sources. In addition, the expression of alpha1, 2-FT was differentially regulated and the uterine factor was not prerequisite of the expression of Ley.

[Effect of PIC-BE on the expression of MDR-1 and bcl-2 genes in a multidrug resistance cell variant K562/ADM]

The effect of PIC-BE on the expression of mdr-1, bcl-2 and bax genes and their protein products (P-gp, Bcl-2 and Bax) was observed respectively in a multidrug resistance (MDR) cell variant K562/ADM. The results showed that PIC-BE could significantly inhibit the expression of mdr-1 and bcl-2 genes at both mRNA and protein levels in K562/ADM cell line, and the effect was dose- and time-dependent within limited range. Under same condition, although PIC-BE could increase the expression of Bax slightly, there was no statistically significant difference. These results suggest that the reversal of the MDR of K562/ADM cell line by PIC-BE may result from its effect on the expression of mdr-1, bcl-2 genes and their protein products.

Immunolocalization of Le(y) oligosaccharide in endometrium during menstrual cycle and effect of early luteal phase mifepristone administration on its expression in implantation stage endometrium of the rhesus monkey

Changes in carbohydrate expression on endometrial and blastocyst cell surfaces may play a critical role in the process of implantation. Le(y) is an oligosaccharide antigen which has been shown to be involved in blastocyst attachment in the mouse. In the present study, immunohistochemical distribution of Le(y) in endometrium during proliferative and secretory phases of normal menstrual cycles in the rhesus monkey was examined. Endometrial samples were collected on cycle days 7 (n=4), 13 (n= 4), 16 (n=4), 20 (n=4) and 25 (n=3). There was a gradual increase of Le(y) in luminal surface from proliferative to periovulatory (P < 0.001), and from periovulatory to postovulatory (P < 0.05), phases. Le(y) then remained constant in the midsecretory phase and decreased (P < 0.01) during the premenstrual phase. Le(y) score in glands did not change between the phases, except in midsecretory phase when it was higher than that in other phases (P < 0.05). The stromal compartment showed no statistically significant changes. The profiles of endometrial Le(y) on day 6 after ovulation in mated fecund cycles with or without early luteal phase mifepristone treatment were also examined. Females were allowed to cohabit with males during days 8-16 of their ovulatory cycles and were injected s.c. with vehicle (n=7) only, or with a single dose of mifepristone (2 mg/kg body weight; n=8) on day 2 after ovulation. Significant decreases in the area and optical absorption of immunoprecipitate were observed in the epithelial compartment (P < 0.01) following mifepristone treatment. There was no change in the stromal compartment either in area or in optical absorption of immunoprecipitate for Le(y) with or without mifepristone treatment. The expression of Le(y) in the endometrial epithelial compartment appears to be influenced by progesterone and may be associated with endometrial receptivity prior to implantation in the rhesus monkey.

Effects of monoclonal antibody directed to LeY on implantation in the mouse

The role of carbohydrates in embryo implantation in the mouse was investigated using an embryo transfer model and a blastocyst-uterine epithelial cell co-culture system. The monoclonal antibody (mAb) AH6 directed to LeY oligosaccharide (Fuc alpha1-2 Gal beta 1-4 [Fuc alpha1-3] GlcNAc) and other three mAbs directed to carbohydrates whose structures are closely related to LeY were used to show the effect of carbohydrate specificity on implantation. In the embryo transfer model, donor blastocysts (4 days post-coitus) were pretreated with mAb AH6 (experimental) or other mAbs (control) and transferred into one uterine horn of a recipient. The implantation rate was checked after 5 days. Implantation was significantly inhibited by mAb AH6 pretreatment, and inhibition was not observed in control groups. In the co-culture system, the attachment and outgrowth rate of blastocysts on the surface of uterine epithelial cells was significantly inhibited when monolayer epithelial cells or blastocysts were pretreated with mAb AH6. The most obvious effect of mAb AH6 was obtained during 2-4 h co-incubation. No inhibition was observed in the control groups. It was, therefore, concluded that oligosaccharide LeY recognized by mAb AH6 plays an essential role at the initial stage of implantation. It may act as a mediator molecule for adhesion between the surface of blastocyst and epithelial cell, and its function is carbohydrate-specific.

[Distribution of obese protein in the mouse tissue]

In the present study, the contents of obese protein of tissue from liver, brain, abdominal wall fat, skeletal muscle and the contents of plasma OP of mice were measured with radio immunoassay. The results showed that the contents of OP were much higher in the brain than that in the abdominal wall fat tissue (P < 0.01). The liver and the skeletal muscle tissue did not show the presence of OP. The contents of OP of abdominal wall fat tissue were lower in the female than that in the male mice (P < 0.05).

Monoclonal antibody directed to Le(y) oligosaccharide inhibits implantation in the mouse

We investigated the role of carbohydrates in blastocyst attachment to the uterine epithelium. Le(y) (Fuc alpha 1-->2Gal beta 1-->4[Fuc alpha 1-->3] GlcNAc) was localized by indirect immunofluorescence to the surface of the mouse blastocyst and uterine epithelium. Western blot analysis showed that Le(y) is carried on many uterine glycoproteins in both pregnant and nonpregnant females; however, new species were detected on Day 4 postcoitum (p.c.) coincident with the onset of uterine receptivity. The function of Le(y) in implantation was tested by injecting monoclonal antibody (mAb) directly into the uterine lumen on Days 3-5 p.c. The effects of intrauterine injections on implantation were scored by comparing the number of viable embryos to the number of CL on Day 10 p.c. Injection of purified anti-Le(y) IgM into the uterine lumen on the afternoon of Day 4 significantly inhibited implantation. This effect was dose-dependent and was obtained during a narrow time window, from 87 to 93 h p.c. Inhibition of implantation was not observed in contralateral uterine horns injected with saline, nor was it observed in uterine horns injected with other anti-carbohydrate mAbs. We conclude that binding of anti-Le(y) to the blastocyst or luminal epithelium masks a ligand involved in implantation. Although the mechanism of inhibition is unknown, we show that Le(y) can interact with another oligosaccharide (H) that has been described as a possible uterine ligand for blastocyst attachment. We hypothesize that Le(y) and H form carbohydrate-carbohydrate interactions that promote close apposition of cell surface membranes during an early step in implantation.

Globo-series carbohydrate antigens are expressed in different forms on human and murine teratocarcinoma-derived cells

The glycolipids of human teratocarcinoma-derived cell line NCCIT were compared with those of 5 murine teratocarcinoma-derived cell lines. Glycolipid antigens were identified by cell surface immunofluorescence and high-performance thin-layer chromatography (HPTLC) immunostaining with a panel of monoclonal anti-carbohydrate antibodies. Human NCCIT embryonal carcinoma (EC) cells contained extended globo-series glycolipids Gb5 (galactosyl globoside) and GL7 (sialyl galactosyl globoside) recognized by antibodies to stage-specific embryonic antigens 3 and 4 (SSEA-3 and -4). SSEA-4 was not detected by immunofluorescence on the surface of any of the 5 murine teratocarcinoma-derived cell lines examined; however, SSEA-3 was detected on the surface of murine cell lines resembling primitive endoderm (JC44, NF-PE) and trophectoderm (E6496D). HPTLC analysis revealed a large amount of globoside (Gb4) in these differentiated cells, which may account for their labeling with anti-SSEA-3 antibody. Globo-series glycolipids were also detected in murine EC cells; however, differences were noted between the 2 cell lines examined. F9 cells contained primarily Gb4 and Forssman glycolipid, whereas NF-1 cells contained only minor amounts of Gb4 and lacked Forssman glycolipid entirely. Our results, coupled with the known distribution of Forssman antigen in the egg cylinder-stage mouse embryo, suggest that F9 and NF-1 murine EC cells are replicas of cells at different stages of development of the embryonic ectoderm. Glycolipids of normal mouse embryos were examined for comparison. Gb4 and Forssman glycolipid were presents in both embryonic and extra-embryonic tissues, whereas Gb5 and GL7 were restricted to visceral yolk sac and placenta. Our results demonstrate that human and murine teratocarcinoma-derived cells both synthesize extended globo-series glycolipids; however, oligosaccharide chain elongation takes different pathways in the 2 species. These differences reflect species-related and cell type-specific patterns of glycosylation.

Embryonal carcinoma cells differentiate into parietal endoderm via an intermediate stage corresponding to primitive endoderm

F9 embryonal carcinoma (EC) cells were used as a model system to study endoderm formation during mammalian embryogenesis. F9 cells treated with retinoic acid (RA) or RA plus dibutyryl cyclic AMP (cAMP) were examined for the expression of stage-specific embryonic antigen-3 (SSEA-3), a cell surface marker of primitive and visceral endoderm. SSEA-3 was not detected by indirect immunofluorescence on the surface of undifferentiated stem cells; however, a subset of SSEA-3-positive cells appeared with time in culture, amounting to 20% of cells 10 days after plating. When cultured in the presence of RA, the percentage of SSEA-3-positive cells increased to 70% of cells 10 days after plating. In contrast, treatment of cells with RA plus cAMP yielded differentiated cells that were SSEA-3-negative. These SSEA-3-negative cells exhibited ultrastructural features of parietal yolk sac endoderm. In contrast, SSEA-3-positive cells appearing in cultures treated with RA alone exhibited ultrastructural features of primitive endoderm on day 3, switching to ultrastructural features of parietal endoderm on day 10. Cells with hybrid features, resembling both visceral and parietal yolk sac, were also seen. We suggest that differentiation of F9 EC cells into parietal yolk sac-like cells can occur along two distinct pathways: 1) direct under the combined influence of RA and cAMP; and 2) indirect, under the influence of RA alone, in which cells first differentiate into primitive endoderm. Parietal yolk sac-like cells induced through the latter pathway continue to express SSEA-3, a cell surface marker of primitive endoderm that is not normally found on parietal endodermal cells in vivo.

Clinical use of homograft stored by vitrification

Using 20% DMSO and 6% propylene glycol in Kreb' Ringer phosphate solution as cryopotective agent for homograft vitrification storage, the viability of stored homograft (79.2%) was higher than that of slow cooling storage (59.7%). About 540000 cm2 of vitrified homograft were used to cover the wounds after excision of burn eschar in 135 patients with major burns. The take-rate was over 94%. The cryopreservation of skin by vitrification can improve the viability and quality of skin and save time and cost.

[Effects of different cooling rate on the viability of cryopreservation of skin]

The three methods of stored skin by vitrification and slow cooling and vitrification+slow cooling were studied in order to improve the viability of stored skin. The results showed that the viability (oxygen consumptions and succinate dehydrogenase) of skin cryopreserved by vitrification was superior than by slow cooling and vitrification+slow cooling. The viability of homograft stored by vitrification was 61% compared with that for other two groups of 51.7% and 49.2% (P < 0.05). So the skin stored by this vitrification may be suitable for clinical use.

Influence of low density lipoproteins on cytosolic free Ca2+ concentration and dense tubular system in human platelets

The cytosolic free Ca2+ concentration [Ca2+]i and dense tubular system (DTS) of washed human platelets were affected by low density lipoproteins (LDL) of 25 micrograms/ml at 37 degrees C for 10 minutes. After the incubation with LDL, the [Ca2+]i increased from 115 +/- 29 nM to 141 +/- 24 nM. LDL promoted the increase of [Ca2+]i (471 +/- 31 nM) induced by thrombin (0.03 U/ml) as compared to that which thrombin did alone (240 +/- 11 nM) (p < 0.05). The increased Ca2+ influx from the extracellular space is thought to be the reason of the increase in [Ca2+]i, since the effect of LDL was abolished by removal of external Ca2+ by EGTA. The DTS changed primarily from thin elongated forms to rounded vesicles. No evidence was noticed that LDL caused a mobilization of Ca2+ from the DTS.

[Experimental and clinical study of skin stored by vitrification]

To improve the quality of stored skin, vitrification storage method (rapid cooling) was introduced. G group cryoprotective solution (20% DMSO and 6% propylene glycol in kreb's Ringer phosphate solution) was selected from 7 different kinds of solution with low toxicity and high cryoprotective activity. G group solution was proved very effective in cryopreservation of small and large pieces of guinea pig skin. Fresh cadaveric skin, 0.3-0.4 mm in thickness, with an area of 500-1,000 sq.cm was soaked in G group solution for 30 min. After being sealed in plastic bags, the skin was put directly into liquid nitrogen. The skin was thawed in 40 degrees C water bath before use. The cooling rate was about 2160 degrees C/min (by fine transient thermometer). The viabilities of stored skin measured by oxygen consumption (microelectrolyte method) and succinic dehydrogenase (by modified Hershey's method) were about 70% as prestored value, and were 20% higher than those stored by slow cooling method. 250000 sq.cm of vitrified skin stored for one to two years were used in 135 operations for major full thickness burns after tangential excision or excision of eschar. The taken-rate was over 94%. The color of skin turned to red within 3-4 days after grafting. There was no blister formation on the surface of grafted skin. If autologous micro-skin were put underneath the stored skin or small pieces of autologous skin were inserted into the small holes of the stored skin, the wounds healed smoothly within six weeks after operation and no further grafting was needed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a cell differentiation inducer, ganglioside GM3, on the neutral glycosphingolipid composition and cell membrane fluidity of a human promyelocytic leukemia cell line HL-60

In this paper the authors confirmed the finding reported by Nojiri et al that exogenous ganglioside GM3 could induce HL-60 cells to differentiate along the monocytic-macrophage route with significant inhibition of proliferation. It was found that after differentiation the neutral GSL content of CDH and CMH increased, while that of CXH, a polyhexosyl ceramide with a TLC mobility slower than CQH, decreased significantly. The membrane fluidity of HL-60 cells decreased after GM3 treatment.

Molecular biology of carbon-phosphorus bond cleavage. Cloning and sequencing of the phn (psiD) genes involved in alkylphosphonate uptake and C-P lyase activity in Escherichia coli B

Whereas bacteria such as Escherichia coli have been known for some time to cleave carbon-phosphorus (C-P) bonds in unactivated alkylphosphonates, the enzymes responsible for C-P lyase activity have resisted detection or purification. Genes from E. coli B that support growth on alkylphosphonates as the sole phosphorus source have now been cloned (B. L. Wanner and J. A. Boline, unpublished data). Deletion analysis demonstrated that at least 13 kilobases of DNA information is required for E. coli to express the phosphonate utilization phenotype (Phn+). The complete nucleotide sequence of 15,611 bases has been determined, and the gene structures were examined. Seventeen open reading frames (phnA to phnQ) were identified in one transcriptional direction and five open reading frames in the divergent direction. Sequence homology searches identify PhnC, PhnK, PhnL, and, possibly, PhnN proteins as members of nucleotide-binding proteins of the binding protein-dependent transport systems. Candidates for other membrane components and regulatory proteins are also identified. A Pho box-like promoter sequence is also found upstream of the gene cluster starting at phnA, which is consistent with the observation of phosphate regulation of the Phn+ response. Fourteen repetitive extragenic palindromic sequences are found in the phn DNA: 10 exist in the extragenic region between phnA and phnB, two between phnD and phnE, and two between phnK and phnL. An unusual finding is that one of the repetitive extragenic palindromic sequences actually overlaps with the reading frame of the phnE gene.

Transporting of sodium and calcium cation in erythrocyte in patients with essential hypertension

The sodium and calcium cation transport in erythrocyte and their influencing factors were studied in essential hypertensive (EH) patients. The result showed that plasma sodium pump inhibitor, endogenous digitalis-like compound (EDLC), rose in some patients and sodium pump was depressed in the others, but there were no parallel links between EDLC and sodium pump. The patients with normal sodium pump have mainly shown a decrease of their maximal CA++ pump activity and calmodulin (CaM) content in erythrocyte. It indicated that there might be different types of ion transporting defect in EH, and the abnormalities of these cation transports might be an important pathogenesis in EH.

Homology of a yeast actin-binding protein to signal transduction proteins and myosin-I

In yeast, the cortical actin cytoskeleton seems to specify sites of growth of the cell surface. Because the actin-binding protein ABP1p is associated with the cortical cytoskeleton of Saccharomyces cerevisiae, it might be involved in the spatial organization of cell surface growth. ABP1p is localized to the cortical cytoskeleton and its overproduction causes assembly of the cortical actin cytoskeleton at inappropriate sites on the cell surface, resulting in delocalized surface growth. We have now cloned and sequenced the gene encoding ABP1p. ABP1p is a novel protein with a 50 amino-acid C-terminal domain that is very similar to the SH3 domain in the non-catalytic region of nonreceptor tyrosine kinases (including those encoded by the proto-oncogenes c-src and c-abl), in phospholipase C gamma and in alpha-spectrin. We also identified an SH3-related motif in the actin-binding tail domain of myosin-I. The identification of SH3 domains in a family of otherwise unrelated proteins that associate with the membrane cytoskeleton indicates that this domain might serve to bring together signal transduction proteins and their targets or regulators, or both, in the membrane cytoskeleton.

Isolation and characterization of mutations in the HXK2 gene of Saccharomyces cerevisiae

Several hundred new mutations in the gene (HXK2) encoding hexokinase II of Saccharomyces cerevisiae were isolated, and a subset of them was mapped, resulting in a fine-structure genetic map. Among the mutations that were sequenced, 35 were independent missense mutations. The mutations were obtained by mutagenesis of cloned HXK2 DNA carried on a low-copy-number plasmid vector and screened for a number of different phenotypes in yeast strains bearing chromosomal hxk1 and hxk2 null mutations. Some of these mutants were characterized both in vivo and in vitro; they displayed a wide spectrum of residual hexokinase activities, as indicated by three assays: in vitro enzyme activity, ability to grow on glucose and fructose, and ability to repress invertase production when growing on glucose. Of those that failed to support growth on fructose, only a small minority made normal-size, stable, and inactive protein. Analysis of the amino acid changes in these mutants in light of the crystallographically determined three-dimensional structure of hexokinase II suggests important roles in structure or catalysis for six amino acid residues, only two of which are near the active site.

[Sodium and calcium cation transport of erythrocytes in essential hypertension]

The sodium and calcium transport of erythrocyte and the influencing factors were studied in essential hypertensive (EH) subjects. The result showed that plasma endogenous digitalis-like compound (EDLC) increased and sodium pump depressed in some EH patients, but there were no parallel correlation between EDLC and sodium pump. The patients with normal sodium pump mainly showed their maximal Ca2+ pump activity and decreased calmodulin (CaM) content of erythrocyte. Thus there may be different types of ion transport defect in EH, and the abnormalities of these cation transports have an important role in the pathogenesis of EH.

The use of blood in burn shock. Clinical and experimental study

We have given whole blood as one of the main constituents of burn shock resuscitation for the past 28 years. To appraise the value of using whole blood, we have summarized the clinical experience of 2630 burn patients. Overall mortality was 4.18%. The lethal area of the burn were 50% of the population is expected to die was 82.8% total body surface area and 57.4% third-degree burns. The incidence of renal failure, pulmonary edema, and gastrointestinal bleeding was 0.9%, 0.4%, and 0.6% respectively. To confirm the advantage of transfusion of whole blood, we have carried out a series of experimental studies. Two groups of 25 dogs with 25% total body surface area full-thickness burns were treated with two resuscitation regimens. Group I was treated with whole blood, and group II with no blood, during the shock phase. After 48 hours, the infusions were stopped. Measurements were made before the burn and 2, 24, 48, 72, and 144 hours after the burn injury. The animals were then killed for histologic studies. From our data, we concluded that whole blood used in burn shock did not increase hemoconcentration or viscosity; it improved anemia, oncotic pressure, hypoproteinemia, acid-base balance, oxygenation, hemodynamics, and myocardial contractility, promoted cardionatrin secretion, reduced edema of tissue, and protected viscera from degenerative changes and bacterial colonization.

[Optimal conditions for the storage of split-thickness skin at 4C]

Split-thickness human skin must, out of necessity, be stored for days to years prior to usage as a burn wound covering. This study was designed to utilized three different parameters of tissue viability in order to determine optimum conditions for skin survival at 4 degrees C for various periods of time in RPMI-1640 media. Viability was determined by 1) trypan blue dye exclusion of trypsinized basal cells (TBC), 2) 14C-leucine incorporation into TBC, and 3) in vitro skin explant growth. Electron microscopy was also done on selected samples.

METHODS

Split-thickness (0.2-0.3 mm) cadaveric skin (obtained within 24 hours of death) was divided into 6 tubes containing RPMI-1640 (pH 7.3) supplemented with 10% Nu-serum and 25 mM Hepes. The ratio of skin to media varied from 0.2 to 8.0 cm2/ml. The samples were then stored at 4 degrees C for up to 4 weeks with weekly changes of media.

RESULTS

Following 7 days storage, optimal viability (as determined by averaging the viabilities obtained from the above assays) was found for samples stored at a ratio of 2 cm2/ml (90.3 +/- 4.2%). Samples stored at ratios between 1.0 and 6.0 cm2/ml all maintained acceptable viabilities (i.e., greater than 78%), while samples at either 0.2 or 8.0 cm2/ml were both about 57% viable. EM demonstrated edema in all samples. The viability of skin stored for 4 weeks at 2-4 cm2/ml decreased dramatically after 2 weeks.

CONCLUSION

RPMI-1640 is an excellent medium for the storage of split-thickness skin at 4 degrees C, 2-4 cm2/ml, for up to 7 days. Because of the high viability retained in skin stored under these conditions, further long term storage in liquid nitrogen should provide good quality tissue for transplantation.

Compositional analysis of the three main gangliosides from adult human myometrium by a rapid capillary gas chromatographic method

A new capillary GC method is described for the compositional analysis of the three main gangliosides isolated from adult human myometrium. The sample was subjected to methanolysis, acetylation and trimethylsilylation which allows all the constituents to be analyzed simultaneously. The predominant ganglioside was found to be GD3, with GM3 and GT1b the next most abundant.