Biomedical subjects

V H Gattone

Publications and source records attributed to V H Gattone.

At least 73 records · Page 4Linked to original sources

PubMed1986

The effect of angiotensin II on glomerular function and morphology in the rat.

We have observed alterations of glomerular and afferent arteriolar structure in nephrotoxic and ischemic models of acute renal failure. These alterations may have been caused by angiotensin II. To test this notion, we infused the peptide directly into the left renal artery of anesthetized rats. At sub-pressor doses of 1.9 and 6.5 ng/100g body weight/min, the peptide caused dose-related decreases in glomerular filtration rate similar to those that occur in models of acute renal failure. In some animals, methacrylate casts of the infused and contralateral kidneys were made for later examination by scanning electron microscopy. In other animals, the kidneys were fixed with glutaraldehyde for examination of the glomerular epithelium and endothelium by scanning electron microscopy. Cast analysis showed no detectable alteration of afferent arteriolar diameter, and only moderate bilateral changes in the tapering of the arterioles. In contrast, the diameter of the casted glomerular tuft was significantly reduced by the highest dose of angiotensin II. No alterations of the glomerular epithelium or endothelial fenestrae were observed. We conclude that angiotensin II probably did not mediate the changes in glomerular structure in our earlier studies of acute renal failure, even though similar reductions of glomerular filtration rate occurred. Reduced diameter of the glomerular tuft is consistent with a possible role for angiotensin II as a modulator of intrinsic contractile elements in glomeruli.

Acute Kidney Injury↗

PubMed1985

[Na-K]ATPase activity in proximal and distal tubules of the rat kidney: modification and application of a quantitative cytochemical technique.

A modified cytochemical assay for [Na-K]ATPase in cryostat sections of kidney was further characterized and used to quantify activity in seven functionally distinct sites along the rat nephron. The activity of [Na-K]ATPase was defined as the difference in ATPase activity in specifically identified tubules contained in serial sections incubated with and without ouabain. Preincubation of sections with ouabain was required for maximal inhibition of [Na-K]ATPase activity in several distal sites. The concentration of ouabain necessary for maximal inhibition of activity was 3.0 mM and half-maximal inhibition was obtained in all regions with 30-100 microM ouabain. In distal sites, [Na-K]ATPase formed a higher proportion of total ATPase activity (60-80 per cent) than in proximal sites (20-40 per cent). Enzyme activity was quantified using two different methods. The first measured activity over the basal region of tubules and gave an index of the concentration of [Na-K]ATPase over the basal lateral infoldings of cells composing the tubule. The second read activity over the entire cross section of tubules and provided an estimate of [Na-K]ATPase per length of tubule. The highest activities over the basal basal region were obtained from tubules of the distal nephron including the inner (MALin) and outer (MALout) medullary ascending limb, distal convoluted tubule (DCT) and connecting segment (CS). Lower activities were obtained in proximal convoluted (PCT) tubules, proximal straight (PS) tubules and the papillary collecting duct (PD). Distal convoluted tubules contained the highest activity per length of tubule. Other sites contained lower levels of activity in the following order: MALin greater than MALout greater than PCT greater than PD greater than PS. The modifications introduced increase the sensitivity and precision of this assay and permit the application of this technique to studies of [Na-K]ATPase activity in the major functional regions of the rat nephron.

Animals↗

PubMed1985

Time course of glomerular endothelial injury related to pulsatile perfusion preservation.

To elucidate the time course of glomerular and arterial endothelial injury resulting from pulsatile perfusion preservation of human kidneys, we examined two kidneys, one at 16 and the other at 42 hr, for which no suitable recipient could be found. The scanning electron microscope revealed subtle changes at 16 hr in the filtration barrier. These included mild endothelial swelling with an increase in the appearance of bulbous processes, and elongated fenestrae. The visceral epithelial surface was normal as was the arterial endothelial surface. By 42 hr the glomerular endothelial surface displayed very prominent cytoplasmic ridges and clearly distorted fenestrae. The arterial endothelium exhibited a tendency to separate from the vessel wall. The proximal tubular epithelium revealed scattered loss of microvilli. These changes are similar in kind to, albeit less severe than, those described after 60 hr of perfusion. They may represent cell swelling following ischemia, or be the result of altered cell permeability engendered by low temperature. The possibility remains that such changes could be minimized by modifying the perfusate. Scanning electron microscopy provides a versatile tool in the study of vascular and other surfaces of tissues stored with perfusion preservation.

Endothelium↗

PubMed1985

Glomerular endothelial injury related to simple hypothermic storage: an electron microscopic study in the rat.

The present study examined alterations in the glomerular endothelium associated with simple hypothermic storage. Adult rat kidneys were flushed with cold Collins (C2) solution and stored at 8 degrees C for 0, 24, 48, 72 and 96 h after which the kidneys were perfusion-fixed and processed for light and electron (scanning and transmission) microscopy. Glomerular endothelium exhibits a time-related increase in endothelial process swelling and fenestral distortion. From 48 to 96 h of preservation, progressive cellular swelling was accompanied by focal elongation and disruption of the fenestral patterns. These changes contrast the maintenance of a normal glomerular epithelial pattern. All of the tubular elements, however, exhibited progressive changes through this time course including cellular necrosis. The glomerular changes associated with simple hypothermic storage are mild, being limited to the endothelium. These changes are probably of little functional significance when compared to the more marked tubular changes.

Animals↗

PubMed1985

A proposed technique for the morphometric analysis of arteriolar smooth muscle cells from scanning electron microscopic preparations.

Morphometric methods are developed which allow the determination of smooth muscle cell (SMC) features from microvasculature prepared for scanning electron microscopy (SEM). In vessels so prepared, the SMCs are visible as either tapered ends (T) or complete wraps (CW) around the visible vessel. Formulas were developed so that these features could be used to determine the number of cells (C) in a vessel segment and the number of times the smooth muscle cells wrap around the vessel (W/C). Models were constructed to simulate such vessel preparations to test these formulas. From the two pieces of data (C and W/C) so determined, other SMC parameters could be calculated such as: SMC density along the vessel, SMC length and vessel surface area covered by a SMC. Therefore, it is evident that SMC data can be determined from microvessels prepared for SEM. This data would allow a more complete understanding of SMCs and their changes in normal and diseased states.

Animals↗

PubMed1984

Pleuroperitoneal canal closure in the rat.

Pleuroperitoneal canal development and closure were studied with light microscopy and transmission and scanning electron microscopy in 12.75- to 16-day fetuses. The major chronological events described in this paper are 1) the caudal tips of the lung buds projecting to the pleuroperitoneal canal (12.75 through 13.50 days); 2) the caudal tips of the lungs becoming situated medial to the canal areas at 14 days; and 3) both canals becoming crescent shaped with a uniform diameter until closure. Concurrently, the developing diaphragm and associated pleuroperitoneal folds assume more caudal positions. Both canal regions are bordered by the liver, lung, gonadal ridge, and suprarenal glands. In addition, on the left side, the stomach and mesogastrium also border the early canal. The right canal closes before the left (right, 14.75-15 days; left, 15-15.25 days). The results suggest that the pleuroperitoneal folds are pushed together, thereby closing the canals. This may be accomplished by one or a combination of the following: 1) enlargement of the liver pushing the ventral fold dorsad and a molding of the liver to the dorsal body wall caudal to the canal; 2) liver and thorax enlargement which appears to pull the dorsal fold taut against the central fold; and 3) a change in the orientation of the canal near the time of closure. Each canal is fully closed by the mergence of the dorsal and ventral fold mesothelia and mesenchyme. This study provides a basis for relating pleuroperitoneal canal development and closure to the surrounding organs and tissues.

Animals↗

PubMed1984

Renal afferent and efferent arterioles of the rabbit.

The present study employed our microdissection-digestion technique to determine the three dimensional organization of the walls of the afferent and efferent arterioles of the adult rabbit kidney. Each smooth muscle cell of an afferent arteriole is characterized by a somal enlargement and two lateral processes. The cells of the distal segment of the afferent arterioles are modified into myoepithelioid cells, which are closely apposed to one another. The cells of the proximal efferent arteriole are irregularly shaped and regions of adjacent cells may be separated from one another so that gaps exist and areas of the underlying endothelium are not covered by smooth muscle cells. The cells of the distal segments of efferent arterioles are multipolar pericytes, of which the processes branch. Thus the afferent arteriole possesses a complete muscular wall while only the proximal efferent possesses smooth muscle cells with a sphincteric orientation. The distal efferent arteriole possesses pericytes that appear to have a limited capability to modulate renal hemodynamics.

Animals↗

PubMed1984

The effect of streptozotocin and streptozotocin-induced diabetes on the kidney.

The study of diabetic nephropathy in experimental animals generally relies on the chemical induction of the diabetic state. Streptozotocin is commonly employed to that end; however, streptozotocin has an inherent nephrotoxic potential. We studied the effects of both streptozotocin, and diabetes on the kidneys of rats given streptozotocin 60 mg/kg, which was sufficient to induce severe diabetes. Our studies, which utilized both transmission and scanning electron microscopy, considered the pharmacokinetics of streptozotocin in renal tissue, as well as the effect of insulin treatment. Renal tissue kinetics were altered by occluding the renal hilum of one kidney during, and for 5 min after, the administration of streptozotocin. We found that, in contrast to alloxan, streptozotocin caused no detectable renal injury at the dose employed. Previously described renal epithelial papillomas were identified, and were not influenced by altering the renal tissue kinetics of the drug. We conclude that no 'protection' procedure is necessary for the kidney when the streptozotocin model of diabetes is employed. In this regard streptozotocin may have greater utility than alloxan.

Animals↗

PubMed1984

Effect of denervation on the afferent arteriole in the SHR.

To study the role the renal nerves may play in the hypertension of the SHR, we conducted a morphometric study of the afferent arteriole of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) which were subjected to renal denervation (or sham-operation). Methacrylate casts were made of the renal vasculature after perfusion fixation with glutaraldehyde. These vascular casts were then examined and measurements made with the scanning electron microscope (SEM). Afferent arterioles of the denervated SHR were dilated in comparison to the sham-operated SHR, but there was no difference between the afferent arteriolar diameters of the 2 groups of WKYs. However, the afferent arteriolar diameters of the SHR (either group) were smaller than those of the WKY. Renal denervation caused a reduction in systolic blood pressure compared to sham-operated in both strains of rat. We concluded that the dilation changes of afferent arterioles of denervated SHRs may be related to renal autoregulation resulting from the decreased blood pressure. However, the effect of the loss of sympathetic innervation of the arterioles cannot be ruled out.

Animals↗

PubMed1984

Application of scanning electron microscopy to kidney development and nephron maturation.

The present study uses scanning electron microscopy to review mammalian kidney development using the dog model. Canine mesonephros and metanephros are examined, focusing on the structure of the nephron from each and the maturation of the different cell types found in the metanephric nephron. The mesonephros possesses numerous nephrons each with a glomerulus, proximal, distal, and collecting tubule which empty into the mesonephric (Wolffian) duct. The mesonephros does not have cortical and medullary regions. The metanephric nephron not only possesses a glomerulus and the same tubular segments as described for the mesonephric nephron (proximal, distal, and collecting tubules), but also has tubular segments that are found in the medulla, namely the loop of Henle and thick ascending limb. Mammalian metanephric glomerulogenesis and tubulogenesis follows an orderly centrifugal pattern (from inner to outer cortex). The glomerular visceral epithelium initially has a columnar shape which is modified into a cuboidal sheet possessing numerous slender foot processes. The endothelium begins as a double layer with minimal fenestrae. With maturation, a single cell layer is formed possessing many large fenestrae. The maturation of the proximal tubule is documented by changes in the apical microvilli, and the foldings of the lateral and basal cell surfaces. Initially, the collecting tubule is lined by a primordial cell which differentiates into both the principal and intercalated cells.

Aging↗

PubMed1983

Structural changes of isolated hepatocytes during treatment with digitonin.

The structural changes accompanying digitonin-induced release of enzymes and metabolites from isolated hepatocytes have been studied by scanning and transmission electron microscopy. In the initial phase, characterized by total release of the cytosolic marker enzyme, lactate dehydrogenase, the plasma membrane was immediately damaged, rapidly followed by extensive damage to the endoplasmic reticulum. The shape of the cell, however, was maintained, and the mitochondria and nucleus remained tightly held together by the cytoskeleton. Mitochondria remained intact initially, whereas the cytosol became less electron dense and the nuclear chromatin was more dispersed. An intermediate phase was characterized by total release of adenylate kinase and most of the glucose-6-phosphatase, marker enzymes for the mitochondrial intermembrane space and the endoplasmic reticulum, respectively. The outer mitochondrial membrane was ruptured, but mitochondria maintained their normal matrix electron density. In the final phase, characterized by the beginning of citrate synthase release from the mitochondrial matrix space, the mitochondria became swollen, and only the nucleus, inner and outer mitochondrial membranes, and the cytoskeleton could be clearly distinguished. Although the plasma membrane could not be readily discerned in electron micrographs after the initial phase, the plasma membrane marker enzyme 5'-nucleotidase remained associated with digitonin-treated hepatocytes. Acetyl-CoA carboxylase was released much more slowly than lactate dehydrogenase, indicating some severe restriction on its release. The release of acetyl-CoA carboxylase closely paralleled the release of glucose-6-phosphatase. The controlled exposure of hepatocytes to digitonin, therefore, leads to the sequential release of soluble, compartmentalized cellular components and some membrane-bound components, but the mitochondrial membrane, cytoskeleton and the nucleoskeleton survive even long-term digitonin treatment.

Acetyl-CoA Carboxylase↗

PubMed1983

Morphometric comparison of rabbit cortical connecting tubules and collecting ducts.

Connecting tubule (CNT) segments of the rabbit distal nephron were examined by scanning electron microscopy and computer-assisted morphometric analysis of transmission electron micrographs. CNT were very similar to the cortical collecting ducts (CCD) described previously. The epithelium of both segments contains two cell types, both of which can be modeled as simple cuboidal cells, and two distinct systems of extracellular channels. The lateral intercellular channels are comparable to the spaces between simple cuboidal cells but are modified by short projecting microvilli which produce a modest increase in lateral cell surface area. The basal infolded channels are best developed in the connecting tubule cells of CNT and contribute 63% of all channel-associated membranes in CNT. Total membrane areas are similar in CNT and CCD. The two segments differ only in the degree of extracellular channel dilation and the distribution of infolded membrane relative to cell height in the connecting tubule and principal cells. The relatively minor morphometric differences between CNT and CCD do not correlate well with the marked difference in transtubular volume flow induced in the two segments by ADH and an osmotic gradient.

Animals↗

PubMed1983

Glomerular endothelial injury related to renal perfusion. A scanning electron microscopic study.

To elucidate abnormalities in renal morphology related to perfusion preservation, we examined kidneys perfused for 60 hr with a scanning electron microscope. In addition to tubular necrosis and fused glomerular visceral epithelial foot processes, we identified changes in the glomerular endothelial and arterial endothelial surfaces. The glomerular endothelium revealed fenestrae that were smaller and more irregular than normal, as well as abnormal bulbous projections. The arterial endothelium displayed striking degenerative changes. These abnormalities may account for the altered glomerular function and intravascular coagulation that occur in some kidneys preserved by lengthy perfusion.

Adult↗

PubMed1983

Development of solute transport in rabbit proximal tubule. II. Morphologic segmentation.

We examined the segmental morphologic maturation of the proximal tubule in order to identify some of the factors influencing the development of solute transport. Proximal tubules from the outer, middle, and inner kidney cortex were obtained from rabbits during the entire period of development and studied using transmission and scanning electron microscopy, microdissection, and semiquantitative morphometric analysis. The location of the tubule in the cortex was established by identifying its own glomerulus. The 1-wk-old rabbit showed the most immature proximal tubules in the outer cortex and a gradation of more mature tubules toward the inner zone. Only the inner cortical tubules were segmented at this time. The outer cortical tubules showed limited development for the 1st 2-3 wk after birth, while the inner cortical tubules were morphologically mature by 3-4 postnatal wk. Morphometric analysis revealed that the areas of apical, basolateral, and mitochondrial membranes developed at similar rates. Clearly, morphologic maturation of proximal tubules was reached at different times depending on the cortical origin. We conclude that a serial developmental examination of transport in proximal tubules should require the careful identification of the origin of each tubule in the cortex; otherwise, time-dependent comparisons will be complicated by the inclusion of nephrons of diverse postnatal ages. In practice, at this time, the use of proximal tubules from the inner cortex throughout development, or from the outer cortex beyond 2-3 wk of age, permits such serial measurements and comparisons in the rabbit.

Absorption↗

PubMed1983

The morphology of the renal microvasculature in glycerol- and gentamicin-induced acute renal failure.

To elucidate abnormalities in the renal microvasculature that could account for the functional disturbances occurring in two well-established models of acute renal failure, we gave rats a single intramuscular injection of glycerol (50%, 10 ml/kg) or daily subcutaneous doses of gentamicin (100 mg/kg/day). Afferent arteriolar diameters were determined by measuring methacrylate vascular casts with SEM. The filtration barrier was examined by both SEM and TEM. The EF area was quantitated. By 3 hr, the glycerol treatment markedly decreased PADs and DADs (PAD 19.1 to 12.0 micrometers, DAD 13.8 to 7.4 micrometers, p less than 0.05). The changes were similar for both inner and outer cortical regions. By 3 days the vasoconstriction was alleviated; however, renal failure persisted. At that time, however, EF area was decreased to 43% of normal. After 10 days of gentamicin treatment, only minimal vasoconstriction occurred in the outer cortex; however, EF area was decreased to a similar degree as observed with the 3-day glycerol-treated animals. There are two phases to glycerol-induced acute renal failure. The first phase (described as readily reversible) is characterized by intense vasoconstriction. The second phase, which is not immediately reversible, is associated with a decreased EF area. Smaller outer cortical afferent arterioles and a decreased fenestral diameter and density of the glomerular endothelium are seen only after gentamicin-induced renal failure is well established (after 10 days of treatment).

Acute Kidney Injury↗

PubMed1982

Effects of moxalactam and cefotaxime on rabbit renal tissue.

To determine and compare the effects of moxalactam and cefotaxime on kidneys, we gave these drugs in doses of 750 and 1,500 mg/kg to rabbits for 7 days. Cephaloridine was included as a positive control. Neither moxalactam nor cefotaxime at either dose caused lysosomal enzymuria, changes visible by light microscopy or increased plasma creatine. Both drugs caused minor alterations in glomerular ultrastructure at the higher dose. Cephaloridine, on the other hand, caused widespread renal functional and morphological damage. We conclude that in rabbits, both moxalactam and cefotaxime are remarkably nonnephrotoxic.

Acetylglucosaminidase↗

PubMed1982

Scanning electron microscopic study of age-related surface changes in rat femoral head articular cartilage.

The articular surface of the femoral heads of young (5 month-old) and old (21 month-old) female rats were examined with the use of the scanning electron microscope using an especially sensitive preparative technique in which the femoral heads were fixed in a glutaraldehyde-paraformaldehyde fixative, post-fixed in OsO4, dehydrated in ethanol and critical point dried. The articular surfaces of the young group were relatively smooth with only small ridges, which may represent superficial collagen fibrils embedded in a proteoglycan matrix. The old group's articular surfaces differed in 2 ways from the surfaces obtained from the young group. First, circumscribed depressions (roughly 20-25 micrometers in diameter) were found, which may represent the empty lacunae of superficial-layer chondrocytes. Secondly, the articular surface was 'roughened', apparently by numerous exposed collagen fibrils that may have been exposed as a result of a loss of superficial proteoglycans. It is concluded that our methodology of tissue preparations for observation with the scanning electron microscope is a sensitive and practical technique that could be useful for characterizing early morphological manifestations of articular cartilage degenerative changes.

Aging↗

PubMed1982

A scanning electron microscopic study on the pathogenesis of the posterolateral diaphragmatic hernia.

A scanning electron microscopic and light microscopic examination of a left posterolateral diaphragmatic hernia in a 14.7 day rat fetus gives new insight for the pathogenesis of this anomaly. Compared to control specimens of the same age, the pleuroperitoneal canal is larger and round rather than crescent-shaped. Evidence is presented which indicates that the caudal pole of the left lung protruded into the canal region during the 14th day, it appears that the lung interferes with the apposition and fusion of the dorsal and ventral pleuroperitoneal folds. The presence of the lung within the pleuroperitoneal canal prevents canal closure and results in the formation of a posterolateral diaphragmatic hernia.

Animals↗