Mycoplasma pneumoniae Pneumonia—Experience at a Referral Center

Mycoplasma pneumoniae pneumonia is usually a benign illness, and respiratory complications and extrapulmonary manifestations occur rarely. In this series, patients admitted to a referral hospital with this disorder had unusual symptoms, signs and findings on chest roentgenograms and laboratory studies. Pneumonia was often severe and extrapulmonary manifestations were frequent, resulting in prolonged hospital stays and illnesses. Although this extreme end of the spectrum of disease caused by M pneumoniae is not representative of this type of pneumonia as seen in outpatients, it is important to realize that patients admitted to hospital with severe, complicated pneumonia frequently have unusual manifestations of a common disease.     

Analysis of food stimulation of gastrin release in dogs by a panel of inhibitors

The release of gastrin into the serum of five conscious gastric fistula dogs after a meat meal was monitored for 2 hours. Neither the rate of increase in serum gastrin nor the 2 hour cumulative integrated gastrin response was changed by administration of small doses of somatostatin tetradecapeptide (0.5 microgram/kg.hr IV for 2 hr), 16-16 dimethyl prostaglandin E2 (0.25 microgram/kg.hr IV for 2 hr or 1 microgram/kg intragastrically), or bethanechol (20 micrograms/kg.hr IV for 2 hr). Acidification of the food in the antrum to pH 1.2 to 1.4 eliminated serum gastrin release in response to food. In control studies, serum gastrin levels were not altered by IV administration of saline for 2 hr with no food or when a plate of food was held just out of the dogs' reach (teasing). Food-stimulated gastrin release was contrasted with that stimulated by bombesin under identical laboratory conditions [17]. In each case, antral acidification, somatostatin, prostaglandin E2 and bethanechol affected bombesin-stimulated gastrin release differently from that stimulated by food. We conclude that food and bombesin release gastrin by different pathways.     

An analysis of repeated sequence heterogeneity

High-resolution thermal denaturation was used to measure the heterogeneity within repeated DNA sequences. An analysis of combined denaturation/redenaturation experiments on mouse satellite DNA suggests the existence of two minor components, one of which does not appear in the prepared EcoRII monomer. The resolving power of the denaturation/redenaturation experiment is estimated and contrasted with that of the reassociation experiment, often used to estimate repeated sequence heterogeneity. A mathematical model of the redenaturation experiment was developed and applied to mouse satellite data; the results suggest that only one-fourth of the mismatched base pairs are energetically significant in the reduction of heteroduplex stability.     

Solubilization and characterization of the leukotriene C4 synthetase of rat basophil leukemia cells: A novel,participate glutathione S-transferase

Rat basophil leukemia cell homogenates effectively catalyze the conversion of leukotriene A₄ to a mixture of leukotrienes C₄ and D₄ in the presence of glutathione. These homogenates also catalyze the formation of adducts of halogenated nitrobenzene with glutathione, as determined spectrophotometrically. While all the classical glutathione S-transferase activity resides in the soluble fraction of the homogenates, the thiol ether leukotriene-generating activity is found in the particulate fraction. This “leukotriene C synthetase” activity has been solubilized from a crude high-speed particulate fraction by means of the nonionic detergent, Triton X-100. The solubilized enzyme is incapable of converting 2,4-dinitrochlorobenzene to a colored product in the presence of glutathione. Nor will it react with 3,4-dichloronitrobenzene. On the other hand, under optimal conditions, this enzyme preparation is capable of generating about 0.1 nmol leukotriene C mg protein^?1 min^?1 in a reaction which continues in linear fashion for at least 10 min. This dissociation in substrate specificity, as well as differences in the inhibition profile, distinguish the enzyme activity in the particulate fraction from rat basophil leukemia cell homogenates from the microsomal glutathione S-transferase which has been described in rat liver homogenates, suggesting that this “leukotriene C synthetase” is a new and unique enzyme.     

Fast-Growing Rhizobium japonicum That Effectively Nodulates Several Commercial Glycine max L. Merrill Cultivars

Several isolates of fast-growing Rhizobium japonicum that nodulate the wild soybean Glycine soja have been recently described (Keyser et al., Science 215:1631-1632, 1982). We demonstrate that one of these isolates, designated PRC 440 or USDA 191, has a wider host range than that previously reported and is able to nodulate several commercial Glycine max cultivars as effectively as does slow-growing R. japonicum 61A76. Electron microscopic examination revealed no obvious differences between strain 61A76- and strain USDA 191-induced nodules.     

Phosphate Nutrition of Rhizobium spp

This study was conducted to determine the behavior of 40 strains from six species of Rhizobium in liquid defined media containing orthophosphate at levels likely to be encountered naturally, ranging from the high concentrations expected in nodules and artificial media to the low concentrations of soil solutions. Storage capacity in strains with high levels (2 mM) of P and ability to utilize this stored P for growth after transfer to low levels (0.06 μM) of P varied with each strain. Storage varied from about 1 to 2% P (dry weight) for all strains, with the number of generations supported dependent on the quantity of P stored and on the utilization efficiency. The ability to store P at high levels is probably less important than the uptake and utilization efficiency of P supplied at low levels. Strains varied greatly in tolerance to low levels of P maintained in solution by an iron oxide buffering system. Differences in growth rate at low levels of P were large enough to be agronomically important.     

Hyperpolarizing potentials in guinea pig hippocampal CA3 neurons

There is a bewildering variety of hyperpolarizing potentials which control activity in hippocampal pyramidal cells. These include an inhibitory postsynaptic potential (IPSP) with early and late components, voltage- and calcium-dependent potassium conductances, a voltage-dependent potassium conductance modulated by muscarinic agents (the M-current), and a complex and poorly understood afterhyperpolarization following epileptiform bursts. In hippocampal CA3 pyramidal cells, mossy fiber stimulation elicits an IPSP which is made up of two readily separable components. Using the in vitro slice preparation, we investigated the underlying ionic basis of these IPSP components and compared them to other hyperpolarizing potentials characteristic of the CA3 neurons. Intracellular recordings were obtained and then tissue was exposed to bathing medium low in chloride concentration or high in potassium concentration; the ion "blockers" EGTA (intracellular); tetraethylammonium (TEA) (intra- and extracellular), and barium and cobalt (extracellular); and the gamma-aminobutyric acid (GABA)/chloride antagonists penicillin, bicuculline and picrotoxin.     

Sexual dimorphism in weight among the primates: The relative impact of allometry and sexual selection

In this paper, we examine allometric and sexual-selection explanations for interspecific differences in the amount of sexual dimorphism among 60 primate species. Based on evidence provided by statistical analyses, we reject Leutenegger and Cheverud’s [(1982). Int. J. Primatol.3:387-402] claim that body size alone is the major factor in the evolution of sexual dimorphism. The alternative proposed here is that sexual selection due to differences in the reproductive potential of males and females is the primary cause of sexual dimorphism. In addition, we propose that the overall size of a species determines whether the dimorphism will be expressed as size dimorphism,rather than in some other form.     

Nile water as a cause of Eastern Mediterranean sapropel formation: Evidence for and against

During the late Pleistocene, sapropels (layers of organic-carbon rich sediment) formed throughout the entire Eastern Mediterranean Basin in close association with glacial/interglacial transitions. The current theory for the mechanism of sapropel formation involves a density stratification of the water column, due to the invasion of a large quantity of low-saline water, which resulted in oxygen depletion of the bottom waters. Most workers believe that this low-salinity water was glacial meltwater that entered the Mediterranean via the Black Sea and a series of interconnected glacial lakes, but the suggestion also has been made that the freshwater originated from the Nile River. In this study the oxygen isotope values of planktonic foraminifera,Globigerinoides ruber, have been examined in six gravity cores and one piston core from the southern Levantine Basin, and compared with the oxygen isotope records ofG. ruber from other areas of the Eastern Mediterranean. This study deals mainly with the latest sapropel which was deposited approximately 7000 to 9000 years ago. Results indicate that Nile discharge probably does reduce salinities somewhat in the immediate area surrounding the mouth of the Nile, but this water is rapidly mixed with the highly saline waters of the easternmost Mediterranean.Using a mixing equation and surface water salinity limitations, an approximate oxygen isotope balance of surface waters was calculated for the time of latest sapropel deposition. This calculation shows that neither Nile River discharge nor Black Sea input (nor both together) are large enough to account for the large-scale oxygen isotope depletion associated with latest sapropel deposition in the Eastern Mediterranean. This suggests that part of the isotopic change at Termination I is probably due to increased surface water salinities during the last glacial maximum. In addition, evidence from the timing of sapropel 1 deposition and the dissolved oxygen balance indicates that deposition of the latest sapropel is associated with increased surface water production of biogenic material, as much as three times higher than that of present day.