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Biomedical subjects

L Barajas

Publications and source records attributed to L Barajas.

At least 73 records · Page 4Linked to original sources
PubMed1977

Unilateral renal hypoplasia with associated venous anomaly and hypertension. A study of the juxtaglomerular cells.

A child with unilateral renal hypoplasia, high plasma renin levels and hypertension was found to have large numbers of juxtaglomerular granular cells in the affected kidney. They were seen adjacent to and sometimes in the interior of hyalinized glomeruli or, in loose nests scattered in the interstitium. Ultrastructurally they contained large numbers of crystalline protogranules in the Golgi region and also displayed other features suggestive of hyperactivity. Atrophic tubules, smooth muscle and mast cells were present in considerable numbers. Well-preserved renal cortex remained in the affected kidney with no demonstrable juxtaglomerular granularity. After unilateral nephrectomy the patient became normotensive and plasma renin levels became normal. Thus it appears that the juxtaglomerular cells are able to produce and release renin independent of the structural integrity of the juxtaglomerular apparatus and renal glomerulus.

Child↗
PubMed1977

Post-transplant hypertension. Normoreninemic severe hypertension treated by bilateral nephrectomies.

In a nineteen-year-old male in whom severe and protracted hypertension developed after a successful renal transplantation, the removal of the diseased kidneys resulted in restoration of normal blood pressure. Prenephrectomy blood samples obtained from the venous drainage of all three renal veins demonstrated no evidence for excessive renin secretion, nor was a significant difference in renin activity found between any two kidneys. It is postulated that the patient may be a clinical variant of the experimental form of renal hypertension with normoreninemia. Alternatively, the remnant kidneys may be implicated to produce a nonrenin pressor substance.

Adolescent↗
PubMed1977

Segmental intrarenal catheterization in renin-mediated hypertension.

Segmental renal vein blood was collected in 9 hypertensive patients who had a focal renal lesion on excretory urography and/or a high peripheral plasma renin activity. The main renal vein catheterization was normal in all patients. Segmental renal vein catheterization demonstrated a renin-producing lesion in 3 patients, all of whom were cured of the hypertension postoperatively. Segmental renal vein catheterization is safe and allows the recognition of increased renin production from focal lesions of the kidney that may not be demonstrated radiographically or by main vein catheterization.

Adolescent↗
PubMed1977

Structure of a juxtaglomerular cell tumor: the presence of a neural component: a light and electron microscopic study.

A 15-year-old girl with hypertension, markedly elevated plasma renin activity, and normal aortogram had a well encapsulated tumor nodule removed from the right kidney. Following surgery, the plasma renin activity and blood pressure became normal and have remained so for the past 12 months. The tumor consisted of juxtaglomerular cells filling the interstitium between endothelium-lined vascular spaces. Electron microscopy disclosed the presence in the interior of the tumor, of unmyelinated nerve bundles with varicosities containing the small, densely cored vesicles characteristic of adrenergic nerves. Nerve terminals were in contact with the juxtaglomerular tumor cells. No basement membrane material was interposed between the nerve endings and the tumor cell; the width of the gap between the two plasma membranes was approximately 150 A. The presence of sympathetic fibers in the juxtaglomerular cell tumor underscores the close biologic relationship between the sympathetic and renin systems.

Adolescent↗
PubMed1976

Cholinergic innervation of the simian oxyntic gastric mucosa.

The innervation of the oxyntic gastric mucosa was studied by light and electron microscopy in the rhesus monkey. An abundant net of acetylcholinesterase-positive nerves was seen in the lamina propria, with many slender fibers noted close to the basal lamina of the glands. Electron microscopic observation disclosed the presence of nerve fibers containing axons and varicosities in the lamina propria, often in very close proximity to the epithelial glandular cells. Nerve endings partly enveloped by a Schwann cell were occasionally seen in direct contact with a parietal cell.

Animals↗
PubMed1976

Light and electron microscopic localization of acetylcholinesterase activity in the rat renal nerves.

Acetylcholinesterase activity is shown in the renal nerves of the rat with the technique of Karnovsky and Roots. By light microscopy, the acetylcholinesterase-positive nerves are seen in association with blood vessels, including the glomerular arterioles, and occasionally with renal tubules. By electron microscopy the precipitate appears extracellularly around axons and varicosities. DFP inhibits the deposition of precipitate. Previous demonstration by serial section electron microscopy in the rat revealed that all nerves around the glomerular arterioles contain small dense-cored vesicles characteristic of adrenergic nerves, indicating that the acetylcholinesterase-positive nerves demonstrated here are likely to be adrenergic nerves containing acetylcholinesterase.

Acetylcholinesterase↗
PubMed1976

The renal sympathetic system and juxtaglomerular cells in experimental renovascular hypertension.

Marked reduction of the monoaminergic nerve fluorescence and catecholamine tissue content were demonstrated in the ischemic kidney of rats made hypertensive by unilateral renal artery stenosis (two-kidney Goldblatt hypertension). The nonischemic kidney showed a normal degree of fluorescence and catecholamine content. The electron microscope failed to demonstrate recognizable nerves around most of the glomerular arterioles of the ischemic kidney, whereas a normal rich innervation was observed in the nonischemic side. The juxtaglomerular index and renal renin content were elevated in the ischemic kidney and markedly reduced in the nonischemic kidney. Juxtaglomerular cells were present in the glomerular mesangium and ultrastructurally showed changes consistent with increased renin synthesis. The extent of disruption of the sympathetic system in renal hypertension might play a role in the degree of hypersecretory response of the juxtaglomerular cells to renal artery constriction.

Animals↗
PubMed1975

The large-scale isolation of renin-containing granules from rabbit renal cortex by zonal centrifugation.

A new method for the isolation of renin-containing granules from rabbit renal cortex by sequential two-dimensional centrifugation is presented. A mitochondrial fraction produced by preparative differential centrifugation was subjected to isopycnic centrifugation on combined discontinuous and linear density gradients in the same SZ-14 reorienting gradient zonal centrifuge rotor. Renin activity, as assayed by radioimmunoassay for angiotensin I, was localized in a region of the density gradient with a corresponding density of 1.196 Gm. per cubic centimeter or 1.53 M sucrose. The renin-containing granules were enriched 5.0-fold over whole homogenate levels, while peroxisomes were enriched 17.4-fold, lysosomes 23.4-fold, and mitochondria 4.3-fold. Electron microscopic examination of the fraction with highest renin activity showed a granular fraction almost free of contamination from other subcellular material. The data supports the view that renin-containing granules are a distinct subcellular particle. This new method for the large-scale isolation of renin-containing granules makes it possible to obtain the quantity of material necessary to study the release renin at the subcellular level and permit the further biochemical purification and characterization of the enzyme.

Acid Phosphatase↗
PubMed1972

Phagocytosis of microbial L-forms.

Little data are available regarding L-form phagocyte interactions. Due to difficulty with more conventional methods, a serum-free technique of surface phagocytosis employing cellulose ester micropore filters, fluorochrome staining, and reflecting fluorescence microscopy was developed. Intracellular localization of L-frms was confirmed by electron microscopy. In timed experiments, phagocytosis of a group D Streptococcus (ATCC 23241) and its L-form (T53I) were maximal at 30 min, although the bacteria were consistently better phagocyted. Phagocytosis of an Escherichia coli (strain Yale) and its L-form was also demonstrated with the same technique. The lesser phagocytosis of L-forms may be related to their lower chemotactic activity.

Enterococcus faecalis↗