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Biomedical subjects

E R Hall

Publications and source records attributed to E R Hall.

65 records · Page 4Linked to original sources
PubMed1977

Acute copper poisoning of cultured marine teleosts.

Copper was accidentally introduced into seawater entering a circular outdoor tank used to culture 610 pinfish (Lagodon rhomboides) and other marine teleosts. Fish were exposed for 23 hours to copper concentrations between 0.2 parts per million (ppm) and 7.2 ppm with an average concentration of 3.3 ppm. The pinfish were lethergic by 6 hours after copper was introduced into the tank. Deaths began within 10 hours with a total of 575 (94%) deaths. Deaths stopped 11 hours after copper concentrations decreased below 0.2 ppm and signs of distress stopped in surviving pinfish by approximately 6 hours after the last death. Serum urea nitrogen, alkaline phosphatase, sodium (Na+), and potassium (K+) concentrations were increased and represent those constitutents which differ from mean control values by more than 2 standard deviations. Electrolyte imbalance, apparently resulting from impaired osmoregulation and hemolysis, was a serious terminal condition in copper-poisoned pinfish.

Animals↗
PubMed1975

Experiments in marine biochemistry. Homarine metabolism in Penaeus duorarum.

A fractionation procedure has been developed which permits the isolation of 1 to 2 mg of homarine from a single shrimp. This procedure was used to show that homarine is endogenously synthesized by Penaeus duorarum in the free unbound form, and to study the metabolic precursors involved. Injected DL-[14C]tryptophan was not converted to [14C]homarine. However, [6-14C]quinolinic acid, a known catabolite of tryptophan, is an effective precursor. [2-14C]Acetate and [U-14C]glycerol are effectively converted to [14C]homarine while [14C]bicarbonate is poorly utilized. The injection of L-[U-14C]aspartate resulted in labeled homarine, but the quantity converted was less than expected. Since [14C]glycerol is an effective precursor there is a possibility that quinolinic acid may be formed in P. duorarum by a condensation similar to that of glyceraldehyde 3-phosphate with aspartic acid or a closely related metabolite. It is suggested that decarboxylation of quinolinic acid gives rise to picolinic acid which is methylated to yield homarine. L-[methyl-14C]Methionine efficiently provides the N-methyl carbon presumably via S-adenosylmethionine.

Acetates↗
PubMed1971

Survival of Listeria monocytogenes in experimentally infected mice.

Physiological saline was found to be very detrimental to the viability of Listeria monocytogenes. The LD(50) value was substantially reduced when peptone was used as the suspending fluid rather than saline. Normal splenic tissue was not inhibitory to the survival of Listeria. In experimentally infected mice, L. monocytogenes survived for 8 days in the peritoneal cavity and for at least 11 days in the spleen.

Animals↗
PubMed1971

Rapid method for the isolation of Listeria monocytogenes from experimentally infected mice.

Listeria monocytogenes was successfully isolated from experimentally infected mice by placing homogenized tissues in phosphate-buffered saline (PBS), trypsin, peptone, or pepsin followed by incubation at 37 C for 24 hr. A larger number of Listeria isolates were recovered from the trypsin or PBS splenic homogenate suspensions incubated at 37 C for 2 hr than from the other diluent suspensions. Holding infected tissues at 4 C for at least 3 months did not increase the efficiency of Listeria isolation. Listeria L-forms were not isolated from mice injected with the bacterial form. The in vitro viability of Listeria L-forms suspended in PBS or PBS splenic homogenate was greatly reduced when held at 4 C.

Agar↗
PubMed1968

Listeria monocytogenes L forms. I. Induction maintenance, and biological characteristics.

L forms were induced from 15 of 16 strains of Listeria monocytogenes on penicillin gradient plates incubated under aerobic conditions. The culture medium for maintenance of these L forms must contain an electrolyte in a concentration of 1% or sucrose in a concentration of 10%. The electrolytes NaCl, KCl, or MgSO(4) were used in both induction and maintenance media. Induction of L forms occurred more rapidly on media containing KCl. Listeria L forms had the same fermentation reactions as the parent bacterium. The L-form growth in liquid medium was slow, not extensive, and appeared as clumps on the bottom of culture tubes. The morphology of Listeria L forms was similar to that reported for other bacterial L forms. The L forms derived from strain 10403, serotype 1, were stable after two or more passages on penicillin media. They did not revert to the bacterial form after 40 subcultures on penicillin-free media. Some L-form colonies derived from strain 10403 did revert to the bacterial form when transferred directly from induction plates to penicillin-free media. Studies of the growth characteristics for L forms derived from strain 10403 gave the following results: an optimal temperature of 30 C, high electrolyte or sucrose concentration necessary for induction and maintenance, and no requirement for serum.

Calcium Chloride↗