Peter A. Nickerson

Ligating the ductus arteriosus before birth remodels the pulmonary vasculature of the lamb.

ABSTRACT: The clinical syndrome of persistent pulmonary hypertension of the newborn includes a developmentally abnormal pulmonary microvasculature which contains excessive amounts of muscle and which cannot adapt to air breathing in the perinatal period. Surgical ligation of the ductus arteriosus of the fetal lamb has produced a physiologic model of pulmonary hypertension of the newborn. The aim of the present investigation is to determine whether surgical ligation of the ductus arteriosus in fetal sheep produces anatomic changes in the pulmonary blood vessels. The pulmonary vasculature of seven neonatal lambs that underwent surgical ligation of the ductus arteriosus from 6 to 17 d before birth was compared to that of five control lambs with a patent ductus arteriosus without fetal surgery and three control lambs with a patent ductus arteriosus that underwent sham surgery. Quantitative microscopic analysis of the barium gelatin-filled peripheral pulmonary vascular bed revealed an increase in the proportion of partially and fully muscularized pulmonary arteries at the level of the terminal bronchiole and within the acinus (p<0.0001). This finding demonstrates that medial muscle develops in areas of the distal pulmonary vascular bed where it is normally absent. Periadventitial fibrosis surrounding intraacinar pulmonary arteries was also present. No change in the number of small intraacinar arteries was detected. This structural remodeling of the peripheral pulmonary vascular bed was initiated in utero by ductus arteriosus occlusion. Prenatal closure of the ductus arteriosus for 6 to 17 d in fetal lambs produces anatomic changes in small pulmonary arteries of the newborn lamb. These anatomic changes are similar to pathologic alterations reported in human neonates dying with idiopathic persistent pulmonary hypertension of the newborn.

Pulmonary hypertension alters soluble guanylate cyclase activity and expression in pulmonary arteries isolated from fetal lambs

The nitric oxide (NO)‐guanosine 3′,5′‐cyclic monophosphate (cGMP) signaling pathway plays an important role in the pulmonary vascular transition at birth. We studied pulmonary arteries and veins isolated from normal late‐gestation fetal lambs and from fetal lambs with persistent pulmonary hypertension (PPHN) following prenatal ligation of the ductus arteriosus. We additionally used double immunolabeling and immunoblot analysis to determine relative vascular contents of endothelial nitric oxide synthase (NOS‐III) and soluble guanylate cyclase (sGC).

Mechanisms of adjuvancy: I—metal oxides as adjuvants

The exact mechanism of how immune adjuvants function still remains largely unknown, despite their long history of use. This work reports the properties of alum and the related compounds Al(OH)3 or Al2O3. Experiments were performed in rats to determine the relative adjuvancy of silica, talc, ground glass, Al2O3, SnO2, ZrO2, hematite and magnetite. Antibody response and cell-mediated immunity (CMI) to ovalbumin (OVA) were determined and were found to be significantly enhanced by silica and talc. Antibody response to OVA was moderately enhanced by Al2O3, hematite, and magnetite, while CMI to OVA was not affected, SnO2, ZrO2, and ground glass only gave a slight adjuvant effect. The magnitude of adjuvancy appeared to correlate with the magnitude of the inflammatory response produced by each metal oxide and also correlated with their surface area. No correlation could be drawn between the hydrophilicity or hydrophobicity of the metal oxides and the magnitude of their adjuvancy.

Primary cultures of rabbit renal proximal tubule cells: I. Growth and biochemical characteristics

SummayBefore the usefulness of a new in vitro model can be ascertained, the model must be properly defined and characterized. This study presents the growth rate and biochemical characteristics of rabbit renal proximal tubule cells in primary culture over a 2-wk culture period. When grown in a hormonally defined, antibiotic-free medium these cells form confluent monolayer cultures within 7 d after plating. Multicellular done formation, an indicator of transepithelial solute transport, was expressed after confluent cultures were formed. The activity of the cytosolic enzyme, lactate dehydrogenase, and the lysosomal enzyme,N-acetyl-glucosaminidase, increased 14- and 2-fold during the first 8 d of culture. respectively. In contrast, the activity of a brush border enzyme, alkaline phosphatase, decreased 85% within the first 8 d of culture. Release of these enzyme markers into the culture medium, which are routinely used to measure cytoxicity, stabilized after 8 d in culture. The ratio of cellular protein to DNA changed according to the state of cellular growth. Values rose from 0.035 mg protein/μg DNA in preconfluent cultures to 0.059 mg protein/μg DNA in confluent cultures. These results document the characteristics of a primary proximal tubule cell culture system for future studies in in vitro toxicology.

Both mitogen activated protein kinase and the mammalian target of rapamycin modulate the development of functional renal proximal tubules in matrigel

Tubules may arise during branching morphogenesis through several mechanisms including wrapping, budding, cavitation and cord hollowing. In this report we present evidence that is consistent with renal proximal tubule formation through a process of cord hollowing (a process that requires the concomitant establishment of apicobasal polarity and lumen formation). Pockets of lumen filled with Lucifer Yellow were observed within developing cords of rabbit renal proximal tubule cells in matrigel. The observation of Lucifer Yellow accumulation suggests functional polarization. In the renal proximal tubule Lucifer Yellow is initially transported intracellularly by means of a basolaterally oriented p-aminohippurate transport system, followed by apical secretion into the lumen of the nephron. Consistent with such polarization in developing tubules, Triticum vulgare was observed to bind to the lumenal membranes within pockets of Lucifer Yellow-filled lumens. As this lectin binds apically in the rabbit renal proximal tubule, T. vulgare binding is indicative of the emergence of an apical domain before the formation of a contiguous lumen. Both epidermal growth factor and hepatocyte growth factor stimulated the formation of transporting tubules. The stimulatory effect of both epidermal growth factor and hepatocyte growth factor on tubulogenesis was inhibited by PD98059, a mitogen activated protein kinase kinase inhibitor, rather than by wortmannin, an inhibitor of phosphoinositide 3-kinase. Nevertheless, Lucifer Yellow-filled lumens were observed in tubules that formed in the presence of PD98059 as well as with wortmannin, indicating that these drugs did not prevent the process of cavitation. By contrast, rapamycin, an inhibitor of the mammalian target of rapamycin, prevented the process of cavitation without affecting the frequency of formation of developing cords. Multicellular cysts were observed to form in 8-bromocyclic AMP-treated cultures. As these cysts did not similarly accumulate Lucifer Yellow lumenally, it is very likely that processes other than organic anion accumulation are involved in the process of cystogenesis, including the Na,K-ATPase.

HETEROGENEOUS DISTRIBUTION OF SOLUBLE GUANYLATE CYCLASE IN THE PULMONARY VASCULATURE OF THE FETAL LAMB

Vascular segments in the fetal lung differ anatomically and functionally from one another. At birth, the nitric oxide (NO) pathway plays an integral role in reducing pulmonary vascular resistance through a marked vasodilation. However, the contributions of each vascular segment to this dilation are unclear. We sought to determine the distribution of soluble guanylate cyclase (sGC), the enzyme NO activates to induce vasodilation across the pulmonary vasculature.

Light and ultrastructural studies of renal oncocytic adenoma

An asymptomatic renal oncocytoma was found in the upper left quadrant of an eighty-five-year-old woman during a routine physical examination. Ultrastructurally, the tumor was composed entirely of epithelial cells filled with normal and abnormal mitochondria. Selective renal angiography showed two renal arteries supplying a lobulated, highly vascular mass. The mass contained irregular and tortuous vessels without any arteriovenous shunting.

Malakoplakia of the large intestine found incidentally at necropsy: light and electron microscopic features.

Malakoplakia of the large intestine found incidentally at necropsy: Light and electron microscopic features Annand Chaudhry;Krishna Saigal;Marilyn Intengan;Peter Nickerson; Diseases of the Colon & Rectum

Induction of intranuclear inclusions by estrogen in mammotrophs of the mongolian gerbil

Inclusions have been induced in the nucleus of mammotrophs in male and female Mongolian gerbils by injection of estradiol. No inclusions could be observed within nuclei of the anterior pituitary gland of control-injected male gerbils, although a small number were normally present within mammotrophs of female gerbils receiving control injections (0.44 ± 0.07 inclusions per field). Estradiol induced 3.30 ± 0.10 inclusions per field in males and 3.90 ± 0.09 for females. Inclusions were of two types: membranous and vesicular. Membranous inclusions were smooth surfaced and consisted of many cisternae containing a slightly electron opaque matrix. Vacuolar inclusions were large, often filling the entire cross sectional area of the nucleus. The protein synthetic apparatus of mammotrophs was stimulated by the estrogen inasmuch as rough endoplasmic reticulum became hypertropic. Inclusions may well reflect the hyperactivity of the mammotrophs after stimulation by estrogen.

Magnetic resonance imaging (MRI) and pathophysiology of the rat kidney in streptozotocin-induced diabetes.

Proton magnetic resonance imaging was performed on rats before induction of diabetes with streptozotocin (STZ) and at 2 and 12 days postinduction. Images revealed an increase in maximal longitudinal and axial dimensions of the kidneys at 2 days and a further increase at 12 days. Similarly, an increase in the size of the remaining kidney was seen in a rat which underwent uninephrectomy as a positive control. Two major differences were observed between the kidney undergoing compensatory hypertrophy and those developing diabetic nephropathy: (i) Expansion of the renal vasculature was seen only in images of the diabetic rat; (ii) A loss in conspicuity of the normal corticomedullary junction was seen in the T2-weighted images of the diabetic rat but not in the uninephrectomized rat. Histologic examination revealed that the medulla increased to a size greater than the cortex during diabetic nephropathy whereas the medullary volume was less than that of the cortex during compensatory hypertrophy. In vitro T1 relaxation times in cortex, outer medulla and inner medulla of kidneys from control rats were measured and compared with the same respective regions in diabetic rats. When these values were correlated with tissue water content, a linear increase in relaxation rate versus percent water content from cortex to inner medulla was found in the control kidneys, but this correlation was absent in diabetic nephropathy. These studies demonstrate that MRI is an effective noninvasive tool for studying the course of renal hypertrophy and hydration changes in the development of renal disease in STZ-induced diabetes in the rat.