Induction of heat shock protein 72 prevents neutrophil-mediated human endothelial cell necrosis

OBJECTIVE

To examine the hypothesis that induction of heat shock proteins in human endothelial cells (ECs) by either heat shock or sodium arsenite could prevent subsequent EC necrosis induced by activated human polymorphonuclear neutrophil leukocytes (PMNs).

DESIGN

Cultures of ECs were exposed to heat shock (42 degrees C, 30 to 60 minutes) or sodium arsenite (40 to 320 mumol/L) for 6 hours to induce the expression of a heat shock protein of 72-kd molecular weight (HSP-72). Activated PMNs were subsequently added to these ECs for 24 hours to evaluate the ability of HSP-72 to prevent activated PMN-mediated EC necrosis.

RESULTS

Neither EC necrosis nor apoptosis was induced by heat shock. Sodium arsenite (40 to 80 mumol/L) did not induce EC necrosis, although 320-mumol/L sodium arsenite caused a significant increase in EC necrosis. Sodium arsenite (80 to 320 mumol/L) also induced dose-dependent EC apoptosis. Endothelial cells exposed to heat shock and sodium arsenite (40 and 80 mumol/L) significantly attenuated subsequent EC necrosis induced by activated PMNs. However, sodium arsenite at 320 mumol/L aggravated activated PMN-mediated EC necrosis. Expression of HSP-72 was detected after ECs were treated both with heat shock and sodium arsenite (40 to 320 mumol/L) for 6 hours.

CONCLUSION

Induction of HSP-72 in ECs by a thermal or nonthermal mechanism could prevent activated PMN-mediated EC necrosis, which may favor increased vascular permeability during systemic inflammatory response syndrome.

Taurolidine, an antilipopolysaccharide agent, has immunoregulatory properties that are mediated by the amino acid taurine

Taurolidine has bactericidal and antilipopolysaccharide properties. It is broken down into the amino acid taurine, which has been shown to modulate intracellular calcium activity, a critical component in the priming and activation of macrophages and polymorphonuclear leukocytes. We hypothesized that taurolidine may function to enhance immune activity in these cells. The aim of this study was to investigate the immunological effects of taurolidine and correlate findings with survival after a septic challenge in a murine model. Study 1: CD-1 mice underwent cecal ligation and puncture, were randomized to receive taurolidine (200 mg/kg body weight/i.p.) or saline control, and studied for end point survival. Study 2: CD-1 mice were randomized to receive taurolidine (200 mg/kg body weight/i.p.) or saline control. Peritoneal macrophages (PM luminal diameters) were assessed for O2-, NO, tumor necrosis factor-alpha (TNF-alpha), CD11b, phagocytosis, and PMN influx. O2-, TNF-alpha, CD11b expression, and phagocytosis were significantly increased in the taurolidine group. Study 3: PM luminal diameters were cultured in vitro +/- 0.5 mg/ml taurolidine and PM luminal diameter antimicrobial function assessed (O2-, NO, TNF-alpha, and phagocytosis). O2-, TNF-alpha, and phagocytosis were significantly increased, whereas NO was reduced. Study 4: PM luminal diameters were also cultured with taurine (0.5 mg/ml). Similar increase in O2-, TNF-alpha, and phagocytosis were identified. Intracellular PM luminal diameter [Ca2+] was also assessed and increases in free, unbound intracellular [Ca2+] occurred after taurine culture. Thus, in addition to its bactericidal and antilipopolysaccharide activity, taurolidine primes PM luminal diameters for enhanced antimicrobial activity and these effects appear mediated by the amino acid taurine.

Role of lipopolysaccharide and tumor necrosis factor-alpha in induction of hepatocyte necrosis

The occurrence of acute hepatic failure during systemic inflammatory response syndrome (SIRS) is related to the extent of hepatocyte (HC) damage and cell death resulting from necrosis or apoptosis. We hypothesized that proinflammatory mediators such as lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha) can, either directly or indirectly through neutrophil (PMN) and Kupffer cell (KC) activation, induce HC damage and cell death, and that the mechanism is cellular necrosis rather than apoptosis. The results in this study demonstrated that LPS and TNF-alpha alone and in combination are directly cytotoxic to cultured rat HC as indicated by the hepatocellular enzyme release and HC necrosis. However, LPS and TNF-alpha, in the presence of sodium arsenite (a heat shock inducer), were unable to induce HC apoptosis. Both KC and PMN activated by either LPS or TNF-alpha induced significant hepatocellular enzyme release and HC necrosis, which was dependent on the ratio of KC and PMN to HC. It is concluded that LPS and TNF-alpha may play a central role in the development of acute hepatic failure after severe trauma and sepsis by directly or indirectly inducing HC necrosis rather than apoptosis.

Role of nitric oxide in lung injury associated with experimental acute pancreatitis

This study evaluated the effect of varying the synthesis of nitric oxide with sodium nitroprusside or N-nitro-L-arginine methyl ester (L-NAME) in a pancreatitis-lung injury model. Rats (n = 45) were randomized to control or caerulein-induced pancreatitis groups, treated with saline, sodium nitroprusside (0.4 micrograms/kg) or L-NAME (10 mg/kg). Myeloperoxidase activity was used as a measure of neutrophil infiltration. Wet to dry (W:D) lung weight and bronchoalveolar lavage (BAL) protein concentrations were used to assess vascular leakage. Pancreatitis was shown to induce pulmonary neutrophil influx: mean(s.e.m.) myeloperoxidase activity 6.79(0.5) units/g in caerulein-treated animals versus 2.08(0.5) units/g in controls (P < 0.001). Animals with pancreatitis showed increased microvascular leakage compared with controls (mean(s.e.m.) W:D lung weight 7.01(0.5) versus 2.85(0.2), P < 0.001; BAL protein concentration 2539(222) versus 347(32) micrograms/ml, P < 0.001). Compared with the saline-treated pancreatitis group, these changes were reduced by sodium nitroprusside (mean(s.e.m.) myeloperoxidase activity to 2.5(0.4) units/g, P < 0.001; W:D lung weight to 3.8(0.37), P < 0.001; BAL protein concentration 1389(182) micrograms/ml, P < 0.05). L-NAME exacerbated the pancreatitis-induced pulmonary oedema (W:D lung weight increased to 11.96(0.6), P < 0.001), protein leakage (BAL protein concentration rose to 3707(309) micrograms/ml, P < 0.05) and neutrophil infiltration (myeloperoxidase activity increased to 9.01(0.3) units/g, P < 0.05). These data suggest that, in vivo, nitric oxide inhibits pancreatitis-induced lung injury, possibly in part by inhibiting pulmonary neutrophil influx.

Exposure of the peritoneal cavity to air regulates early inflammatory responses to surgery in a murine model

Factors in circulating air may play a role in immune responses after surgery through induction of gut-derived lipopolysaccharide (LPS) translocation across the gut. CD-1 mice were randomized to one of four treatment groups: controls, laparoscopy with carbon dioxide inflation, laparoscopy with air inflation and laparotomy. The peritoneal and systemic immune response was assessed by evaluating peritoneal macrophage, blood monocyte and neutrophil activity. In a second study, the effect of each of the treatments on fluorescein isothiocyanate (FITC)-LPS translocation across the gut was assessed. There were significant (P < 0.05) increases in peritoneal tissue macrophage release of superoxide and tumour necrosis factor after laparoscopy with air and laparotomy compared with control procedures and carbon dioxide laparoscopy. However, peritoneal macrophage FITC-Candida albicans ingestion was significantly decreased after air laparoscopy and laparotomy compared with controls and carbon dioxide laparoscopy (P < 0.05). These findings correlated with a significant (P < 0.05) decrease in CD11b expression. Significant translocation into the peritoneal cavity and systemic circulation occurred after air laparoscopy and laparotomy only. Factors in circulating air can induce LPS translocation and subsequent stimulation of postoperative immune responses. The beneficial effects of laparoscopic surgery may be explained by the minimal air contamination of the peritoneal cavity.

Characterization of the defects in murine peritoneal macrophage function in the early postsplenectomy period

Postsplenectomy bacterial sepsis may be fatal, due to defects in both cellular and humoral immune responses. The objective of this study was to assess the efficacy of peritoneal macrophage antibacterial function in the early postsplenectomy period. Murine models of splenectomy and sham operation were characterized and peritoneal macrophages were harvested 24 h to 1 wk after surgery. Cells from splenectomized animals demonstrated a nonsignificant delay in phagocytosis of Escherichia coli at 24 h with, however, significantly impaired killing of intracellular organisms at 24 h and 1 wk compared to the sham group. Paradoxically, the production of the macrophage antibacterial product superoxide anion was not impaired at either time point in the splenectomy group compared with sham-operated and control mice. Nitric oxide release was significantly lower in the splenectomized group (p = 0.006), a possible explanation for reduced bacterial killing. Mortality from bacterial peritonitis was significantly higher with concomitant splenectomy than in the sham splenectomy group at 24 h (p &lt; 0.02). The production of TNF from macrophages was up-regulated immediately following splenectomy, a cytokine which may contribute to mortality from bacteremic shock. Local defects in macrophage antimicrobial function may contribute significantly to bacteremia and to subsequent mortality in the early postsplenectomy period.

Characterization of the defects in murine peritoneal macrophage function in the early postsplenectomy period

Postsplenectomy bacterial sepsis may be fatal, due to defects in both cellular and humoral immune responses. The objective of this study was to assess the efficacy of peritoneal macrophage antibacterial function in the early postsplenectomy period. Murine models of splenectomy and sham operation were characterized and peritoneal macrophages were harvested 24 h to 1 wk after surgery. Cells from splenectomized animals demonstrated a nonsignificant delay in phagocytosis of Escherichia coli at 24 h with, however, significantly impaired killing of intracellular organisms at 24 h and 1 wk compared to the sham group. Paradoxically, the production of the macrophage antibacterial product superoxide anion was not impaired at either time point in the splenectomy group compared with sham-operated and control mice. Nitric oxide release was significantly lower in the splenectomized group (p = 0.006), a possible explanation for reduced bacterial killing. Mortality from bacterial peritonitis was significantly higher with concomitant splenectomy than in the sham splenectomy group at 24 h (p < 0.02). The production of TNF from macrophages was up-regulated immediately following splenectomy, a cytokine which may contribute to mortality from bacteremic shock. Local defects in macrophage antimicrobial function may contribute significantly to bacteremia and to subsequent mortality in the early postsplenectomy period.

Failure of macrophage activation in experimental obstructive jaundice: association with bacterial translocation

Bacterial translocation from the gastrointestinal tract and macrophage activation are central to current theories of sepsis. The relevance of both in obstructive jaundice is unclear. The effect of bile duct ligation for 7 days on bacterial translocation to mesenteric lymph nodes and on macrophage activation in a rat model was examined. Compared with an incidence of zero in sham-ligated controls, bile-duct ligated rats had a 67 per cent incidence of Gram-negative colonization of mesenteric lymph nodes. This was associated with a significant (P < 0.001) decrease in macrophage tumour necrosis factor, superoxide anion and nitric oxide production compared with that in sham controls. Spontaneous bacterial translocation occurs in experimental obstructive jaundice and is associated with marked suppression of macrophage activation. This suggests a mechanism whereby jaundiced patients may be more susceptible to persistent infection but relatively protected against uncontrolled sepsis.

Immune function in patients undergoing open vs laparoscopic cholecystectomy

BACKGROUND

Abnormal release of inflammatory mediators following surgical injury is associated with immunological alteration, which may predispose to sepsis. Laparoscopic surgery is associated with reduced postoperative complications, but mechanisms are unclear. We hypothesized that early recovery following laparoscopic surgery may relate to minimal impairment of immune function.

DESIGN

Analysis of the temporal immune responses in two similar groups of patients randomized to open (n = 22) vs laparoscopic (n = 22) cholecystectomy. Patients were matched for age, height, weight, and operation time. Immune parameters, including monocyte superoxide anion (O2-) and tumor necrosis factor release, neutrophil O2- levels and chemotaxis, total white blood cell counts, partial arterial oxygen pressure, and serum cortisol and C-reactive protein levels were assessed preoperatively and on postoperative days 1 and 3.

RESULTS

There were significant increases (P < .001) in monocyte release of O2- and tumor necrosis factor, neutrophil release of O2- and chemotaxis, and white blood cell count in the open vs laparoscopic cholecystectomy study groups, with a concommitant decrease in partial arterial oxygen pressure. These findings correlated with significantly higher postoperative septic complications in the open cholecystectomy group (P < .05). There were no significant differences in either plasma cortisol or C-reactive protein levels between groups. All measurements were carried out in a blinded fashion.

CONCLUSIONS

This study demonstrates that laparoscopic surgery appears to be associated with similar metabolic responses compared with open surgery, while immune parameters vary greatly between groups. The beneficial effects of laparoscopic surgery may relate, in part, to preservation of immune function in the postoperative period.

Nitric oxide (endothelium-derived relaxing factor) attenuates revascularization-induced lung injury

Aortic occlusion and revascularization (I-R) may lead to lung injury dependent on activated neutrophil adherence. Nitric oxide (NO) inhibits neutrophil adherence to endothelial cells. We studied the effect of increasing or decreasing NO levels with sodium nitroprusside (SNP) or N-nitro-L-arginine methyl ester (L-NAME) in an I-R lung injury model of 30 min ischemia followed by 120 min reperfusion. Sprague-Dawley rats (10/group) were randomized to controls, I-R, I-R treated with L-NAME (10 mg/ml/hr), and I-R treated with SNP (0.2 mg/ml/hr). Myeloperoxidase activity (MPO) was used as a measure of pulmonary neutrophil influx. Pulmonary endothelial permeability was measured by wet:dry weight ratio and bronchoalveolar lavage protein (BAL prot) and neutrophil counts (BAL PMN). Aortic occlusion and revascularization led to significant increases in pulmonary neutrophil influx (6.1 +/- 0.1 MPO u/g vs 3.05 +/- 0.4 MPO u/g in the control group, P < 0.001) and microvascular leakage; BAL prot (347 +/- 32 mg/ml in controls vs 454 +/- 16 mg/ml in the I-R group, P < 0.05); and BAL PMN (0.7 +/- 0.05 in controls vs 1.8 +/- 0.07 PMN/ml in the I-R group, P < 0.001). These changes were exacerbated further by administration of L-NAME (MPO = 8.9 +/- 0.7; BAL prot = 581 +/- 40 mg/ml; BAL PMN = 2.7 +/- 0.16 PMN/ml). Sodium nitroprusside therapy attenuated the I-R-induced lung injury (3.5 +/- 0.4 MPO u/g, P < 0.05 vs I-R; BAL prot = 330 +/- 61 mg/ml; BAL PMN = 0.9 +/- 0.1 PMN/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of endotoxin in mononuclear phagocyte-mediated inflammatory responses

Lipopolysaccharide (LPS), which is derived from the cell wall of gram-negative and some gram-positive bacteria, plays a major role is the pathogenesis of septic shock. Initiation of these responses depends on LPS interaction with a number of immune cells, not least the mononuclear phagocyte (MP). Mononuclear phagocytes bind the LPS/lipopolysaccharide-binding protein complex through the CD14 receptor and thus mediate the release of a wide range of inflammatory mediators. Release of these mediators is teleologically beneficial but under certain circumstances may be detrimental, resulting in the systemic inflammatory response syndrome. The development of this syndrome is not clearly understood but appears, in part, to be dependent on the ability of the host to respond to these mediators. This review evaluates the mechanisms of LPS-MP interaction and the therapeutic strategies aimed at inhibiting this interaction.

A central executive deficit in patients with Parkinson's disease

Eight patients with Parkinson's disease and eight matched controls were tested for concurrent task performance to examine whether Parkinson's disease produces deficits in the coordinating and integrating function of the central executive component of Baddeley's working memory model. Consistent with this prediction, the patients showed a significant decline in performance on a random pursuit tracking task while recalling digit span forward sequences, whereas the controls showed no such change. Performance on the component pursuit and digit span tasks, which did not differ between groups, was equated across subjects by varying the size of a target square and by using individual subjects' digit spans. The patient group also produced poorer word fluency scores and reported higher levels of depression, but there was no significant impairment on the Wisconsin card sort test. There was no association between dual task performance and any psychometric measure, target size, or disease related variables. Baddeley's working memory model is advantageous in providing a rich conceptual basis to explore and characterise cognitive abilities in patients with Parkinson's disease.

Sulfation of estrone and 17 beta-estradiol in human liver. Catalysis by thermostable phenol sulfotransferase and by dehydroepiandrosterone sulfotransferase

Sulfation is a major pathway in humans for the biotransformation of estrogens. However, the nature of the enzymes that catalyze the sulfation of estrone (E1) and 17 beta-estradiol (E2) in human liver is unclear. Human liver contains at least three well-characterized cytoplasmic sulfotransferases, the thermostable (TS) and thermolabile (TL) forms of phenol sulfotransferase (PST) and dehydroepiandrosterone sulfotransferase (DHEA ST). Therefore, we determined optimal conditions for the assay of E1 and E2 ST activities in human hepatic cytosol to compare their properties and regulation with those of the three well-characterized human liver ST activities. Thermal inactivation studies showed that human liver E2 ST and TS PST had very similar thermal stabilities. The thermal inactivation profile of E1 ST suggested that this activity might be related to both DHEA ST and TS PST. Inhibition studies performed with 2,6-dichloro-4-nitrophenol (DCNP) also showed similar inhibition profiles for E2 ST and TS PST. Neither thermal inactivation nor DCNP inhibition studies indicated a possible relationship between TL PST activity and E1 or E2 sulfation. Experiments performed with 20 individual human liver samples showed highly significant correlations between activity levels of E2 ST and TS PST (rs = 0.944, p less than 0.0001), E1 ST and DHEA ST (rs = 0.845, p less than 0.0001), and, to a lesser degree, E1 ST and TS PST (rs = 0.608, p less than 0.01). Ion exchange chromatography of a human liver preparation, followed by assay of all five ST activities, confirmed the important roles played by TS PST and DHEA ST in the sulfation of E2 and E1. Similar results were found by study of the elution patterns of ST activities after ion exchange chromatography of human jejunal mucosal preparations. Partially purified TL PST, however, was unable to catalyze the sulfate conjugation of either E1 or E2. All of these results were compatible with the conclusion that, in human liver, TS PST is the enzyme predominantly responsible for the sulfate conjugation of E2, DHEA ST is the major enzyme responsible for the sulfation of E1, and TL PST does not appear to catalyze the sulfation of either E1 or E2.

Rapid method for measuring extracellular water in yeast preparations

A rapid procedure for the quantitative determination of extracellular water in bulk bakers' yeast was developed on the basis of the solute dilution principle. A reagent is prepared by synthesizing the diazonium ion of p-aminobenzoic acid and coupling it to peptone. This "azopeptone reagent" permits direct colorimetric measurement, which accounts for the rapidity and simplicity of the test. Potential errors due to osmotic effects are avoided by supplementing the reagent with saline and, more importantly, minimizing the duration of contact between reagent and cells. The new method has acceptable accuracy and precision, and may also be suitable for use with other microorganisms.

PREPARATION AND PROPERTIES OF ISOMERIC 2,4-DINITROPHENYL DERIVATIVES OF ALPHA–EPSILON DIAMINOPIMELIC ACID

not available

ISOLATION AND STRUCTURE OF URIDINE NUCLEOTIDE-PEPTIDES FROM AEROBACTER CLOACAE NRC 492

Four closely related uridine nucleotide-peptides isolated from ethanol extracts of penicillin-treated Aerobacter cloacae NRC 492 have been partially characterized. Fractionation of dialyzed extracts on Dowex-1-Cl columns with aqueous lithium chloride solutions, precipitation of the nucleotide-peptides with methanol–acetone, and further separation by paper chromatography and high voltage electrophoresis yielded (a) UDP-GNAc-lact.L-ala.D-glu.meso-dap.D-ala,* (b) UDP-GNAc-lact.L-ala.D-glu.meso-dap, (c) UDP-GNAc-lact.L-ala.D-glu., and (d) UDP-GNAc-lactic acid. The amino acid isomers were identified by micro-enzymic and chromatographic methods.

ISOLATION AND STRUCTURE OF URIDINE NUCLEOTIDE-PEPTIDES FROM AEROBACTER CLOACAE NRC 492

Four closely related uridine nucleotide-peptides isolated from ethanol extracts of penicillin-treated Aerobacter cloacae NRC 492 have been partially characterized. Fractionation of dialyzed extracts on Dowex-1-Cl columns with aqueous lithium chloride solutions, precipitation of the nucleotide-peptides with methanol–acetone, and further separation by paper chromatography and high voltage electrophoresis yielded (a) UDP-GNAc-lact.L-ala.D-glu.meso-dap.D-ala,* (b) UDP-GNAc-lact.L-ala.D-glu.meso-dap, (c) UDP-GNAc-lact.L-ala.D-glu., and (d) UDP-GNAc-lactic acid. The amino acid isomers were identified by micro-enzymic and chromatographic methods.

CHROMATOGRAPHIC SEPARATION OF ISOMERIC DINITROPHENYL DERIVATIVES OF ALPHA–EPSILON DIAMINOPIMELIC ACID

Null

URIDINE NUCLEOTIDE-PEPTIDES FROM AEROBACTER CLOACAE NRC 492. ENZYMATIC SYNTHESIS OF THE PEPTIDES

Null

PREPARATION OF SPHEROPLASTS OF AEROBACTER CLOACAE

A method for the preparation of spheroplasts from Aerobacter cloacae has been devised. Washed cells are exposed to the combined action of lysozyme and 1.0 M tris buffer at pH 9.0 in 20% sucrose. Such treatment weakens the cell wall structure but most cells retain their rod shape. Subsequent dilution with three volumes of distilled water converts the rods instantaneously into spheres. The time of exposure to lysozyme required for satisfactory production of spheroplasts can be greatly reduced if the cells are preincubated with the tris buffer.

SYNTHESIS AND CHARACTERIZATION OFD-XYLOFURANOSE-5-PHOSPHATE

Phosphorylation of 1,2-O-isopropylidene-D-xylose with diphenylphosphoro-chloridate yielded crystalline 1,2-O-isopropylidene-D-xylofuranose-5-diphenyl-phosphate. Subsequent hydrogenolysis in glacial acetic acid over Adams' catalyst quantitatively removed phenyl groups as shown by infrared analysis. Mild hydrolysis in acetic acid for two hours at 80 °C. removed the isopropylidene grouping, and D-xylose-5-phosphate was isolated as an amorphous barium salt. A yield of 81% of theoretical was obtained from 1,2-O-isopropylidene-D-xylose, or an over-all yield of 72% from xylose. The product was characterized through its amorphous barium, disodium, and dipotassium salts, and its crystalline dibrucine and distrychnine salts.

HYDROLYSIS AND POLYMERIZATION OF CYCLIC DIMETHYLETHYLENE OXALATES

Macrocrystalline cyclic oxalates (2,3-dimethyl-5-6-p-dioxanediones) were prepared by vacuum distillation of the polymeric mixture formed on heating ethyl oxalate, and 1, 2-dimethylethylene glycol with an ester-interchange catalyst. Monomeric dimethylethylene oxalate polymerizes less readily than propylene oxalate, and only at an elevated temperature in the presence of a catalyst. Dimethyl substitution therefore confers marked stability on the six-membered ring. Hydrolysis reaches 50% completion almost instantaneously, followed by a slow first order reaction resulting in complete cleavage of the monobasic acid in about one month at room temperature. Hydrolysis constants for the levo- and meso- oxalates are 0.069 and 0.076 days−1 respectively. The crystalline monomers do not possess sharp melting points and represent stereoisomeric mixtures which display optical activity in solution.

PHYSICAL CONSTANTS AND ESTIMATION OF STEREOISOMERIC 2,3-BUTANEDIOLS

The refractive index – temperature relation for optically active and racemic diols is linear, with [Formula: see text] from 25° to 40°C.: for the meso-isomer [Formula: see text] from 25° to 50°C. The specific rotation [Formula: see text]. Measurements of [Formula: see text] and [Formula: see text] in suitably purified mixtures of stereoisomers allow calculation of the percentage of each isomer present. Tests of the method on known mixtures of all three stereoisomers show an experimental error of ±3%. Analyses of five diol samples from pilot plant fermentations of beet molasses by Aerobacter aerogenes reveal 65–87% meso-, from 2 to 16% dextro-, and from 0 to 33% racemic 2,3-butanediol.

PRODUCTION AND PROPERTIES OF 2,3-BUTANEDIOL XXXVI. LINEAR POLYESTERS OF 2,3-BUTANEDIOL

New polyesters with basic units containing 6, 7, 8, 9, 10, 13, and 14 chain atoms have been prepared from levo-2,3-butanediol and ethyl oxalate, ethyl malonate, dimethyl terephthalate, maleic anhydride, succinic, glutaric, adipic, azelaic, and sebacic acids, and from meso-2,3-butanediol and o-phthalic anhydride. Esterification of 2,3-butanediol with a dibasic acid, or its anhydride, is accompanied by a side reaction, in which butanone-2 and the cyclic methyl ethyl ketal are formed. The purified polyesters, with the exception of the poly-malonate, appear to be composed of regularly recurring acid and diol segments over the molecular weight ranges investigated. Without exception they are amorphous resins or balsams. Polyesters formed from saturated aliphatic dibasic acids become progressively softer as the number of methylene groups in the acid segment increases. The polymeric oxalate, on distillation in vacuo, is converted to a macrocrystalline cyclic monomer.

THE STERILIZATION OF GLASS AND CALOMEL ELECTRODES BY ULTRAVIOLET IRRADIATION

By strictly defining the procedure for handling and storing the electrodes, contamination was limited to microorganisms from the air. For the purpose of this investigation, therefore, sterilization is defined as the complete inactivation or killing of air-borne bacteria, yeasts, and molds. If the organisms are not present in such a way as to offer mutual protection from the radiation, the total energy at 2537 Å necessary to inactivate the most resistant organism may be assumed to ensure sterilization. Aspergillus niger v. Tiegh. was identified as the most resistant contaminant, and electrostatic sampling showed that clumps containing up to about 40 spores of A. niger Strain 6277 became air-borne. These clumps required approximately 60,000 μw. min. per cm.2 at 2537 Å for inactivation. Used with the accessory procedures, exposure to 680 μw. per cm.2 for two hours was found to provide a safe margin and to ensure sterilization of carefully cleaned and specially mounted electrodes. A satisfactory design for a crevice-free glass electrode sterilizable by ultraviolet light is described. E.m.f. changes in glass–calomel cells sterilized by the recommended procedure do not exceed 0.4 mv., corresponding to 0.006 pH units.

PHYSICAL PROPERTIES OF POLY-l,2-DIMETHYLETHYLENE PHTHALATE

The polyester derived from levo-2,3-butanediol and o-phthalic anhydride is moderately hard at a number average molecular weight of 660 (DP = 3), and at an average DP of 4 is a brittle glass. Its hardness on the Brinell scale ranges from about 10 at [Formula: see text], to 22–23 at [Formula: see text], where it equals the hardness of Lucite. Water absorption decreases with increasing molecular weight, and reaches a value of 0.08% in 430 days at 25 °C. for a DP 36 resin. A 50% solution of a solid DP 4 resin [Formula: see text] in acetone has an absolute viscosity at 25 °C. of 1.4 centipoises. Apparently molecular solutions are formed in common aromatic hydrocarbons, ketones, alkyl acetates, alcohols, ethers, and chlorinated solvents.

THE RUBBER HYDROCARBON OF ASCLEPIAS SYRIACA L

Milkweed latex collected in mid-July was coagulated in acetone, the coagulum purified, and the rubber examined by chemical and X-ray diffraction methods. Chromic acid oxidation analyses indicate that the monomer is isoprene. The X-ray evidence verifies these results and, further, fixes the polymer as the cis-configuration (rubber) as opposed to the trans-configuration (gutta-percha) of polyisoprene.The solvent-extracted rubber from the leaves appears from the chromic acid oxidation results to be isoprene, but so far no polyisoprene diffraction diagram has been obtained. It is therefore likely that the solvent-extracted leaf rubber is an isoprene polymer of low molecular weight.