Nerve growth factor: biosynthetic products of the mouse salivary glands. Characterization of stable high molecular weight and 32,000-dalton nerve growth factors

Nerve growth factor (NGF) is a protein required for the growth and development of sensory and sympathetic neurons. The NGF is present in high concentrations in male mouse salivary glands, bovine seminal plasma, and snake venom. The physiological significance of NGF in these sources is not known: it might be a part of a high molecular weight (HMW) protein with possibly different biological function and be cleaved to the functional size by proteases. In an attempt to isolate a HMW protein containing as part of its structure the low molecular weight (LMW) NGF (2.5S), mouse salivary glands were homogenized in the presence of either 8 M urea or 6 M guanidine hydrochloride (Gdn X HCl) in order to denature proteases. This procedure revealed that the LMW NGF is a part of two HMW proteins that are biologically and immunologically homologous to the mouse 2.5S NGF. One of these HMW proteins (Mr 32,000 NGF) was purified and shown to be biologically active in the NGF bioassay. Furthermore, this Mr 32,000 NGF was cleaved by the gamma subunit of mouse HMW NGF to the 2.5S NGF. Evidence is also presented that there may be a HMW protein(s) with apparent molecular weights ranging from 94,000 to 200,000 and immunologically homologous to the three subunits (alpha, beta, gamma) of 7S NGF. This HMW NGF is biologically active in the NGF bioassay, and its activity is inhibited by antibody to the beta subunit. Furthermore, in contrast to mouse 7S NGF, this HMW NGF does not dissociate in either 8 M urea or 6 M Gdn X HCl.(ABSTRACT TRUNCATED AT 250 WORDS)     

The origin of indoleacetic acid and indolepropionic acid in rat and human cerebrospinal fluid

Abstract: Using a new high performance liquid chromatographic method we have measured tryptophan, 5-hydroxyindoleacetic acid (5HIAA), indoleacetic acid (IAA), and indolepropionic acid (IPA) in rat and human CSF. Experiments on rats indicate that IPA in CSF is not derived from the CNS but from bacterial metabolism in the intestine. However, IAA in CSF is derived from CNS tryptamine metabolism. Some tryptamine that is formed peripherally diffuses across the blood-brain barrier and augments the tryptamine formed within the CNS. We have concluded from our data that (i) measurements on CSF are a useful way of studying trace amine metabolism in human CNS, but it is essential to establish the anatomical and metabolic origin of any metabolite found in the CSF; and (ii) tryptamine metabolism is more important in man than in the rat.     

The effects of natural substrate discontinuities on the quadrupedal gait kinematics of free‐ranging Saimiri sciureus

Wild primates encounter complex matrices of substrates that differ in size, orientation, height, and compliance, and often move on multiple, discontinuous substrates within a single bout of locomotion. Our current understanding of primate gait is limited by artificial laboratory settings in which primate quadrupedal gait has primarily been studied. This study analyzes wild Saimiri sciureus (common squirrel monkey) gait on discontinuous substrates to capture the realistic effects of the complex arboreal habitat on walking kinematics. We collected high‐speed video footage at Tiputini Biodiversity Station, Ecuador between August and October 2017. Overall, the squirrel monkeys used more asymmetrical walking gaits than symmetrical gaits, and specifically asymmetrical lateral sequence walking gaits when moving across discontinuous substrates. When individuals used symmetrical gaits, they used diagonal sequence gaits more than lateral sequence gaits. In addition, individuals were more likely to change their footfall sequence during strides on discontinuous substrates. Squirrel monkeys increased the time lag between touchdowns both of ipsilaterally paired limbs (pair lag) and of the paired forelimbs (forelimb lag) when walking across discontinuous substrates compared to continuous substrates. Results indicate that gait flexibility and the ability to alter footfall patterns during quadrupedal walking may be critical for primates to safely move in their complex arboreal habitats. Notably, wild squirrel monkey quadrupedalism is diverse and flexible with high proportions of asymmetrical walking. Studying kinematics in the wild is critical for understanding the complexity of primate quadrupedalism.     

Pharmacological dissection of a neural pattern generator

Summary Injection of picrotoxin solutions into the pericardium of lobsters,Homarus americanus, to produce final, estimated blood concentrations of between 8×10^–8M and 4.5×10^–6M led to disruption of the normal motor output to the scaphognathite. The phase separation of the starts of the bursts in the D1 and D2 muscles (Young, 1975) was reduced on the average by 49%; that of L1 and L2 muscles by 16%. The durations of the D1 and L1 bursts increased by 94% and 48% respectively. The phase separation between the starts of the levator and depressor portions of the cycle was not altered. Whilst rhythmic activity persisted ventilatory rates were depressed, and reversals and ventilatory pauses continued to occur. The rate of reversals and their pattern were not greatly altered. Inexplicably, tonic, synchronous spikes occurred in all four groups of muscles, levator and depressor, during periods of severe disruption. It was concluded that in spite of this, the observations supported the proposals of Young (1975) that (a) recruitment of the D2 and L2 bursts normally is delayed partly by inhibition from D1 and L1 units respectively, and (b) termination of D1 and L1 bursts results normally from inhibition due to activity in D2 and L2 units respectively. The findings also indicated that the synaptic mechanism determining timing within the depressor and levator sessions differs fundamentally from that operating between sessions. One mechanism may be based on picrotoxin-sensitive, and the other on picrotoxin-insensitive inhibition.Abbreviations GABA gamma-aminobutyric acid - SG scaphognathite     

Thallium-205 NMR determination of the thermodynamics of the interaction between the thallous ion and gramicidin dimers incorporated into micelles

A study has been made of the thermodynamics of the interaction between the thallous ion and gramicidin dimers incorporated into micelles using thallium-205 NMR spectroscopy. The chemical shift data obtained are interpreted interms of a model in which the dimer has only one tight binding site. The variation of the binding constant over the temperature range 303-323 K is used to determine the changes in enthalpy and entropy of binding giving values of -11.3 kcal/mole and -16 e.u. at 303 K, respectively.     

Enhanced product formation in continuous fermentations with microbial cell recycle*

The effect of partial recycle of microbial cells on the operation of a chemostat has been investigated for two fermentations. Stable steady states without partial cell recycle were obtained for the conversion of D -sorbitol to L -sorbose by Gluconobacter oxydans subsp. suboxydans 1916B and for the conversion of glucose to 2-ketogluconic acid by Serratia marcescens NRRL B-486. The employment of partial cell recycle dramatically increased product formation rates for both fermentations.     

Validity of the work productivity and activity impairment questionnaire - general health version in patients with rheumatoid arthritis

Introduction  

The Work Productivity and Activity Impairment (WPAI) questionnaire is a well validated instrument to measure impairments in work and activities. However, its validation among patients with rheumatoid arthritis (RA) has not been well established. The present study's purpose is to evaluate the construct validity of the WPAI-general health version among RA patients and its ability to differentiate between RA patients with varying health status.