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Biomedical subjects

D Lorenzo

Publications and source records attributed to D Lorenzo.

23 records · Page 2Linked to original sources
PubMed1981

Hyperoxaluria associated with intestinal bypass surgery for morbid obesity: occurrence, pathogenesis and approaches to treatment.

Hyperoxaluria occurs in most patients after the conventional jejunoileal bypass procedure for obesity. The mechanism of hyperoxaluria is complex, involving persistence of dietary oxalate in solution as well as increased colonic permeability to oxalate. Endogenous oxalate formation also contributes to hyperoxaluria. Treatment is unsatisfactory and involves a low-oxalate diet and simultaneous administration of agents which bind oxalate and bile acids, such as aluminum hydroxide. Hyperoxaluria was not present in 21 of 22 patients who had undergone the pancreato-biliary bypass procedure.

Biliary Tract Surgical Procedures↗
PubMed1979

The Rosenblueth phenomenon.

Rosenblueth and Luco demonstrated in 1939 that, during prolonged stimulation of a motor nerve, neuromuscular fatigue is followed by a rise of tension that has been called the Rosenblueth Phenomenon. The purpose of this work was to investigate the Rosenblueth Phenomenon in a cat neuromuscular preparation in which the nerves were severed at different levels and stimulated at 60 Hz for several hours. It was demonstrated that in the longer nerve preparation the Rosenblueth Phenomenon starts earlier and its maximal tension is higher. Acetylcholine sensitivity was studied in the superior cervical ganglion preparation and no change was observed when tested before stimulation, during fatigue, and during the Rosenblueth Phenomenon. It is concluded that the onset and amplitude of the Rosenblueth Phenomenon depend on the length of the peripheral nerve stump: the longer the stump, the earlier and higher the response. It is suggested that the Rosenblueth Phenomenon is produced by an increase in the transmitter release which would be due to axonal progression of molecules along the nerve.

Acetylcholine↗
PubMedDate not supplied

Some aspects of the structural organization of the spinal cord of Gymnotus carapo (Teleostei, Gymnotiformes). I. The electromotor neurons.

The spinal electromotor neurons (EMNs) of Gymnotus carapo from a distinct column dorsal to the central canal. When massively retrograde-labeled with horseradish peroxidase, these neurons show a well-developed dendritic arborization. Dendrites run along the longitudinal axis of the cord and also project toward the dorsal gray and dorsolateral funiculi. Input to the EMNs is mediated by scarce synaptic contacts which show the fine structural characteristics of the so-called "morphologically mixed" junctions. Serial section reconstructions of the junctional areas revealed the occurrence of "gap junctions," dense membranes facing cumuli of microvesicles, and relatively large zones of undifferentiated membranes. Comparative electrophysiological and morphological data suggest that EMN activity may be mediated by electrical transmission. Since neither dendro-dendritic nor dendro-somatic junctions have been observed, other circuitry alternatives are proposed to account for the expected synchronized firing of the EMNs.

Animals↗
PubMedDate not supplied

Application of two-dimensional nmr spectroscopy in the structural determination of marine natural products. Isolation and total structural assignment of 4-deoxyasbestinin diterpenes from the Caribbean gorgonian Briareum asbestinum.

The structures of four novel asbestinin diterpenes isolated in the toxic extracts of the Caribbean gorgonian Briareum asbestinum are discussed. The major metabolite 11-acetoxy-4-deoxyasbestinin B was subjected to a total structural assignment through the concerted application of several 2D nmr techniques that included 1H-1H COSY, RCT-COSY, RCT2 COSY, HC COSY (HMQC), NOESY, proton-detected long range heteronuclear chemical shift correlation (HMBC) and 13C-13C chemical shift correlation spectroscopy (INADEQUATE).

Animals↗