Clostridium perfringens in Meat and Meat Products

A total of 262 specimens of meat and meat dishes were examined for the presence of Clostridium perfringens. Of this total, 161 were raw, unprocessed beef, veal, lamb, pork, or chicken; 101 were processed meats and meat dishes. C. perfringens was isolated from 113 (43.1%) of these specimens. The highest percentage of contamination (82%) was found in veal cuts, and the lowest (4.7%) in sliced sandwich meats and spreads. Only 2 of the 113 isolates were shown to produce heat-resistant spores, which indicates a very low incidence (0.8%) of contamination. These findings indicate that outbreaks of C. perfringens food-borne disease in the Cincinnati area are caused principally by the contamination of the food with vegetative cells or spores of the organism after cooking. Studies of the effects of various holding temperatures on the growth of C. perfringens indicated that, in the range of 5 to 15 C, no multiplication would occur, but that viable cells would still be present at the end of a 5-day holding period. Extremely rapid growth occurred at temperatures around 45 C, and complete inhibition of growth was accomplished between 49 and 52 C.     

Changes in the Activities of Aldolase and of D-Glyceraldehyde-3-Phosphate Dehydrogenase during the Mitotic Cycle in Microspores of Lilium longiflorum

Microspores of Lilium longiflorum were isolated at various stages of development surrounding the mitotic interval and were analyzed for changes in the activities of D-glyceraldehyde-3-phosphate dehydrogenase and aldolase. Fructose 1,6 diphosphate was used as substrate. Activities were measured by the increase in optical density due to the reduction of diphosphopyridine nucleotide. It was found that mitosis occurs during the minimal activity of both aldolase and D-glyceraldehyde-3-phosphate, thus indicating that heightened glycolytic capacity is not necessarily related to mitosis. It was also found that soluble-SH levels were highest when the enzymes were least active. It appeared, therefore, that the "—SH enzymes" are not necessarily activated intracellularly by high concentrations of soluble thiol. These results are discussed in connection with the theory that soluble-SH compounds stimulate glycolysis and in this way initiate mitosis.     

Quantitative Beziehungen zwischen Temperaturreiz und Aktionspotentialen der Lorenzinischen Ampullen

Zusammenfassung Es wurden die Aktionspotentiale der afferenten Nervenfasern aus den Lorenzinischen Ampullen des Katzenhaies (Scylliam) untersucht, während an den Ampullen definierte und thermoelektrisch registrierte Temperaturreize gesetzt wurden. Versuche in situ und an isolierten Präparationen ergaben keinen Unterschied. Die Entladung der Ampullen erwies sich als unempfindlich gegen mechanische Reize, dagegen äußerst empfindlich gegen thermische Einwirkung. Temperaturregistrierungen in den Ampullen zeigten, daß bei thermischen Reizen an der unverletzten Haut starke Temperaturänderungen il den Ampullen ablaufen.Bei konstanter Temperatur zeigt die Einzelfaser eine Dauerentladung, deren Frequenz zwischen 15 und 23° ein Maximum bis zu 65 Impulsen · sec^–1 hat und nach den wärmeren und kälteren Temperaturen stetig bis zum Nullwert abfällt; die äußersten Grenzen sind 2 und 34°. Das Frequenzmaximum des Gesamtnerven liegt bei etwa 20°. Die höchste statische Unterschiedsempfindlichkeit der Einzelfaser erreicht im Bereich des positiven Temperaturkoeffizienten +7 Imp · s^–1 · grad^–1, im Bereich des negativen — 20 Imp · s^–1 · grad^–1. Kältesprünge führen im gesamten Aktionsbereich der Einzelfaser zu einer vorübergehenden Frequenzerhöhung bis 180 sec^–1 mit anschließender Adaptation auf einen niedrigeren Dauerwert; die überschießende Frequenzerhöhung hängt dabei neben der Temperatur vor allem auch von deren Änderungsgesehwindigkeit d/dt ab. Die dynamische Unterschiedsempfindlichkeit erreicht dabei bis—90 Imp·s^–1 · grad^–1, wobei der Receptor auch außerhalb des statischen Aktionsbereiches noch dynamisch erregbar ist. — Bei Wärmesprüngen verhält sich die Entladung genau spiegelbildlich zur Abkühlung; nach vorübergehender partieller oder völliger Hemmung der Entladung stellt sie sich wieder auf einen Dauerwert ein.Isolierte Einzelampullen zeigen dieselben Erregungsgesetze, nur gehen hier die Spikes bei Abkühlung in regelmäßige Wellen über, die schwebungsartig moduliert sind und vermutlich durch Synchronisation von Fasern innerhalb der Ampulle zustande kommen.Das Verhalten der Lorenzinischen Ampullen entspricht qualitativ in allen Punkten dem der Kältereceptoren der Warmblüter; quantitativ sind die Ampullen noch etwas empfindlicher.Die Versuche wurden mit Unterstützung der Deutschen Forschungsgemeinschaft ausgeführt. Den Kollegen an der Zoologischen Station Neapel, insbesondere Herrn Prof. Dr. Reinhard Dohrn, möchte ich an dieser Stelle meinen aufrichtigen Dank für ihre freundliche Hilfe zum Ausdruck bringen.     

Biotransformation of organic sulfides. Part 9. Formation of (S) para-substituted phenyl methyl sulfoxides by biotransformation usingHelminthosporium species NRRL 4671

Phenyl methyl sulfides substituted in thepara position with methyl, fluoro, chloro, bromo, cyano, nitro, amino, acyl, methoxy, thiomethyl and methylsulfinyl groups have been converted to (S) sulfoxides by biotransformation usingHelminthosporium species NRRL 4671. The highest yields and enantiomeric excesses were obtained with bromo, cyano, methoxy, thiomethyl and methylsulfinyl substituents and in two cases (para-Br and -CN) the products could be crystallized to give (S) sulfoxide of ≥ 96% ee.     

ATP and the processivity of Xenopus laevis DNA polymerase α

We use specific restriction fragments as defined primers for DNA synthesis on single-stranded circular phage fd DNA. These structures are relatively poor templates for a highly purified DNA polymerase α from Xenopus laevis eggs. However, DNA synthesis is stimulated about 5-fold by addition of ATP to the reaction mixture. We show that the deoxynucleotide polymers, synthesized in the presence of ATP, are significantly longer than those produced in the absence of ATP. We also show that this effect is due to a more tenacious binding of DNA polymerase α to DNA and conclude that ATP increases the processivity of the enzyme.     

A followup study of the academic attainment and classroom behavior of children with elevated dentine lead levels

To investigate the impact of low-level lead exposure on children's behavior within a natural setting, we assessed the school performance of a sample of 141 elementary school children classified according to dentine lead level. Twenty-two children had “elevated” levels (≥20 parts per million), 71 had “midrange” levels (10.0–19.9 parts per million), and 48 had “low” levels (<10 parts per million). Four types of outcome data were collected: (1) scores on a standardized group intelligence test, (2) teachers' ratings, (3) incidence of academic failure (assignment to remedial aid, grade retention), and (4) observations of classroom behavior. In general, higher dentine lead levels were associated with less favorable school performance, with most covariance-adjustedp-values in the range of 0.05–0.15. The incidence of grade retention was the outcome most strongly related to lead level. The pattern of results suggests a consistent, though weak relationship between children's dentine lead levels and elementary school performance.