Basal and growth hormone-induced hepatic messenger ribonucleic acid expression of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 is independent of hyperinsulinemia and increased energy status in the genetically obese Zucker rat

Genetically obese Zucker rats, like obese humans, have normal or elevated circulating insulin-like growth factor-I (IGF-I) levels in the presence of low GH secretion. Hyperinsulinemia, increased energy status, or other nutritional factors associated with obesity could be responsible for these findings directly by increasing hepatic IGF-I production at the transcriptional or posttranscriptional level. Alternatively, circulating IGF-I could be modulated indirectly by affecting its binding proteins. To further elucidate this point, we quantitated hepatic IGF-I, IGF-binding protein-3 (IGFBP-3), and GH receptor messenger RNAs (mRNAs) expression in obese Zucker rats under different serum GH and insulin conditions using lean rats as controls. Eleven-week-old male rats were studied basally (intact) or after hypophysectomy (hx) at 9 weeks. In each condition, animals were killed before or 6 h after one dose of recombinant human GH (1.5 micrograms/g body weight ip). At this time, in addition to the mRNA expression of the above-mentioned genes, body weight, glycemia, insulinemia, serum GH (rat and human), and serum IGF-I levels were determined. Obese Zucker rats were significantly heavier than controls in all the conditions studied and did not show differences in glycemia. Severely hyperinsulinemic intact obese rats (146.9 +/- 14 vs. 46.3 +/- 3 microU/ml, P < 0.001) showed compared with intact lean rats significantly lower serum GH (2.39 +/- 0.9 vs. 4.98 +/- 0.68 ng/ml, P < 0.01), decreased hepatic IGF-I mRNA and IGFBP-3 mRNA accumulation (IGF-Ia: 79 +/- 5.9% vs. 100 +/- 0.9%, P < 0.05; IGF-Ib: 67 +/- 5.5% vs. 100.1 +/- 1.9%, P < 0.001; IGFBP-3: 54.7 +/- 2.75% vs. 100.5 +/- 1.55%, P < 0.001), and similar circulating IGF-I levels (1439 +/- 182 vs. 1516 +/- 121 ng/ml). Under comparable serum GH levels in GH-treated intact, hx, and GH-treated hx animals, hyperinsulinemia and/or increased body weight present in obese rats were not associated with increased hepatic IGF-I and IGFBP-3 mRNA amount. No differences in GH receptor/GH-binding protein mRNAs were found in any experimental condition. These results suggest that in vivo the imbalance of the serum GH/IGF-I axis present in obesity is primarily due to events distal to the hepatic IGF-I and IGFBP-3 mRNAs expression, which is tightly correlated to GH levels.

Tobacco smoke-induced lung emphysema in guinea pigs is associated with increased interstitial collagenase

We examined the expression of interstitial collagenase and its enzymatic activity in lung damage induced by tobacco smoke. Guinea pigs were exposed to the smoke of 20 cigarettes per day from 1-8 wk. Age-matched guinea pigs were used as controls. At 6 and 8 wk of smoke exposure, lungs exhibited interstitial and peribronchiolar inflammation and moderate emphysematous changes. In situ hybridization of injured lungs revealed patchy expression of collagenase mRNA mainly in macrophages but also in alveolar epithelial and interstitial cells. Immunoreactive protein was detected in alveolar macrophages and in the alveolar walls and interstitium. Collagenolytic activity increased beginning in the 4th wk of exposure (0.7 +/- 0.43 micrograms collagen degraded/mg collagen incubated relative to 0.23 +/- 0.14 in controls; P < 0.05). At 6 and 8 wk, values were 0.85 +/- 0.34 and 0.98 +/- 0.33 compared with 0.25 +/- 0.11 and 0.26 +/- 13 in controls (P < 0.005 and 0.001). Collagen concentration decreased from 50.7 +/- 8.5 mg/g dry wt in control lungs to 40.2 +/- 5.0 and 42.9 +/- 6.0 at 6 and 8 wk of exposure, respectively (P < 0.05). These results strongly suggest that increased interstitial collagen degradation plays a role in the development of lung emphysema.

Increased expression of gelatinases and collagenase in rat lungs exposed to 100% oxygen

Exposure of adult rats to 100% O2 produces a lethal injury by 72 h. We reasoned that matrix metalloproteinases participate in the pathogenesis of hyperoxic lung injury. To that end we studied the expression and activity of gelatinases A and B and interstitial collagenase in lung tissues and bronchoalveolar lavage fluids (BALF) of rats exposed to 100% oxygen for 60 h. Gelatin zymography of BALF samples revealed a 472 kDa molecular species both in controls and oxygen-exposed animals. In addition, BALF from hyperoxic rats exhibited a 95-kDa gelatinase. Likewise, BALF total gelatinolytic and collagenolytic activities were significantly increased in oxygen-exposed rats. In situ hybridization revealed an increase in type IV collagenases as well as interstitial collagenase mRNAs in the oxygen-exposed lungs. The three enzymes were expressed by alveolar macrophages, and in variable degrees by interstitial and alveolar epithelial cells. Immunoreactive gelatinase B and collagenase paralleled the cell localization of the mRNAs but were also detected in the alveolar walls and interstitium. In situ zymography showed gelatinolytic activity in frozen sections of oxygen-exposed lungs but not in normal lungs. The upregulation of these metalloproteinases during acute exposure to 100% O2 suggests that they might contribute to hyperoxic lung damage through the degradation of extracellular matrix components.

Growth retardation and cysteine deficiency in gamma-glutamyl transpeptidase-deficient mice

gamma-Glutamyl transpeptidase (GGT) is an ectoenzyme that catalyzes the first step in the cleavage of glutathione (GSH) and plays an essential role in the metabolism of GSH and GSH conjugates of carcinogens, toxins, and eicosanoids. To learn more about the role of GGT in metabolism in vivo, we used embryonic stem cell technology to generate GGT-deficient (GGTm1/GGTm1) mice. GGT-deficient mice appear normal at birth but grow slowly and by 6 weeks are about half the weight of wild-type mice. They are sexually immature, develop cataracts, and have coats with a gray cast. Most die between 10 and 18 weeks. Plasma and urine GSH levels in the GGTm1/GGTm1 mice are elevated 6-fold and 2500-fold, respectively, compared with wild-type mice. Tissue GSH levels are markedly reduced in eye, liver, and pancreas. Plasma cyst(e)ine levels in GGTm1/GGTm1 mice are reduced to approximately 20% of wild-type mice. Oral administration of N-acetylcysteine to GGTm1/GGTm1 mice results in normal growth rates and partially restores the normal agouti coat color. These findings demonstrate the importance of GGT and the gamma-glutamyl cycle in cysteine and GSH homeostasis.

Four distinct membrane-bound dipeptidase RNAs are differentially expressed and show discordant regulation with gamma-glutamyl transpeptidase

Membrane-bound dipeptidase (MBD) participates in the degradation of glutathione by cleaving the cysteinyl-glycine bond of cystinyl bisglycine (oxidized cysteinyl-glycine) following removal of a gamma-glutamyl group by gamma-glutamyl transpeptidase (GGT). In the mouse, MBD RNA is most abundant in small intestine, kidney, and lung and is represented by four distinct RNA species. These are generated by transcription from two promoters located 6 kilobases apart in the 5' flanking region of the gene and by the use of two different poly(A) addition sites. Promoter I is used primarily in small intestine and kidney, whereas promoter II is most active in lung and kidney. We found a discordance in the expected co-expression of MBD and GGT; as expected, MBD and GGT are both expressed at high levels in the kidney and small intestine. However, in the lung, MBD is expressed at high levels, whereas GGT is almost undetectable. The reverse is true in the seminal vesicles and fetal liver. Thus, although both enzymes may function in concert to metabolize glutathione in kidney and small intestine, in other tissues they appear to act independently, suggesting that they have independent roles in other biological processes.

Retention of p53val135 wild-type function in transgenic mice

We targeted a mutant p53 gene (val135), previously shown to cause tumors in transgenic mice, to the kidney and eye using a gamma-glutamyltranspeptidase promoter. Although transgene RNA was expressed in both tissues, and mutant protein could be detected at high levels in the kidney and was appropriately localized to the nuclei of proximal tubules, no gross or microscopic lesions developed, even when mice were held as long as 75 weeks. When these mice were crossed with transgenic mice carrying HrasT24 (containing a codon 12 mutation) driven by the same promoter, the p53val135 transgene partially suppressed the mutant ras phenotype (proximal tubular hyperplasia and adenomas and carcinomas of the ciliary body and retinal pigment epithelium). The kidneys of double transgenic mice younger than 25 weeks showed less tubular hyperplasia and cystic change than littermates carrying gamma-glutamyltranspeptidase(I)rasT24 alone. By 33 weeks, there was no difference in the severity of the kidney lesions. The eye lesions were less aggressive, and no malignant lesions were identified. Our findings are consistent with the work of others, indicating that p53val135 is not tumorigenic under all conditions; in fact, in some circumstances, it retains some of the suppressing activity of wild-type p53.

Renal abnormality of calcium handling in spontaneously hypertensive rats

Hypercalciuria has been observed in human and experimental hypertension. The distal convoluted tubule (DCT) is the site of fine regulation for Ca2+ excretion. We assessed the cellular factors responsible for Ca2+ reabsorption in the DCT of spontaneously hypertensive rats (SHR). Vitamin D3 dependent Ca-binding protein 28k (CaBP28k), a factor involved in Ca2+ influx, and plasma membrane Ca ATPases (PMCA), a factor involved in Ca2+ efflux, were studied in hypertensive 16-week-old SHR and normotensive Wistar-Kyoto rats (WKY). mRNA levels for CaBP28k, PMCA 2 and PMCA 4 were not different in the two strains. However, CaBP28k protein was more abundant, and PMCA protein was less abundant in SHR than in WKY. PMCA antibody recognized only DCT in the two strains. In conclusion, decreased PMCA in DCT may be responsible for the hypercalciuria in SHR.

Tenascin is an ubiquitous extracellular matrix protein of human renal interstitium in normal and pathologic conditions

Tenascin, a large oligomeric glycoprotein, is a recent addition to a list of increasing extracellular matrix proteins. Previous studies have documented the strong expression of tenascin in embryonic kidney and in both normal and abnormal mature glomeruli implicating an important role of this extracellular matrix protein in nephrogenesis and glomerular scarring. Whether tenascin plays any role in interstitial fibrosis, a common final pathway of tubulointerstitial nephritis, is no known; on the other hand, a detailed knowledge of the structural components of interstitial fibrosis is essential for further studies on other fundamental aspects of this biologically and clinically important process. In this study, the expression of tenascin in the renal interstitium was immunohistochemically evaluated in 208 renal specimens during normal kidney (23 cases), acute tubular necrosis (8), acute tubulointerstitial nephritis (8), chronic primary tubulointerstitial nephritis (30), tubulointerstitial nephritis secondary to glomerular diseases of mild (46) and severe (55) degree, ischemic damage (24), and rejection (14). It was found that in normal kidney tenascin expression was limited to the medullary interstitium. In kidney with tubulointerstitial nephritis, tenascin was ubiquitously and constantly expressed in any areas with tubulointerstitial damage regardless of diagnosis, etiology, the cortical vs. medullary location of the lesions, stage of the fibrogenetic process, density of fibroblasts, or severity of interstitial inflammation in the affected areas. Indeed, strong tenascin expression was seen in areas where there was only interstitial edema or inflammation as judged by routine light microscopic preparations. In summary, this study systematically documents tenascin as a novel extracellular matrix protein selectively expressed in the medullary interstitium in normal kidney, and ubiquitously present in areas with interstitial fibrosis.

gamma-Glutamyl transpeptidase. What does the organization and expression of a multipromoter gene tell us about its functions?

gamma-Glutamyl transpeptidase is a key enzyme in glutathione (GSH) salvage, metabolism of endogenous mediators such as leukotrienes and prostaglandins, detoxification of xenobiotics including environmentally important compounds and carcinogens, and cellular processes dependent on the oxidation/reduction of glutathione. The enzyme is widely distributed, and these functions often occur in separate tissues and in response to different stimuli. Evidence indicates that gamma-glutamyl transpeptidase plays a direct role in some hepatic and renal responses to injury. In the mouse gamma-glutamyl transpeptidase is a single copy gene expressed from at least seven promoters, and many of the transcribed gamma-glutamyl transpeptidase RNAs are restricted in their expression. Studies that combine analyses of cellular processes with a knowledge of gene structure and expression hold promise for unravelling how these two different levels of function are integrated.

Renal neoplasm in acquired cystic kidney disease

The development of renal cell neoplasms ranging from adenoma to metastatic carcinoma is the most serious complication of acquired cystic kidney disease (ACKD). A comprehensive review of the pertinent literature shows that there is up to 50-fold increased risk of renal cell carcinoma in ACKD compared to the general population. The ACKD-associated renal cell carcinoma is seen predominantly in males, occurs approximately 20 years earlier than in the general population, and is frequently bilateral (9%) and multicentric (50%). Acquired cystic kidney disease-associated renal cell carcinoma is frequently asymptomatic (86%), but may be associated with bleeding, abrupt changes in hematocrit, fever, and flank pain or rarely with hypoglycemia, hypercalcemia, or metastases at presentation. Computed tomography seems to provide a better diagnostic yield than sonography or magnetic resonance imaging; nevertheless, large (up to 8 cm) tumors not visualized by any imaging techniques have been reported. It is generally agreed that there is a need for regular screening of symptomatic ACKD patients for early detection of renal cell carcinoma; however, whether screening is needed for asymptomatic patients remains controversial. Nephrectomy is indicated for tumors larger than 3 cm. Management for tumors smaller than 3 cm with persistent symptoms, such as back pain or hematuria, remains controversial, but nephrectomy may be recommended since many of these tumors turn out to be unequivocal renal cell carcinoma. Asymptomatic tumors smaller than 3 cm should be serially screened, and tumor enlargement may be an indication for nephrectomy. Acquired cystic kidney disease-associated renal cell carcinoma accounts for approximately 2% of deaths in renal transplant patients. A median length of survival of approximately 14 months and a 5-year survival rate of 35% are comparable to the same data for renal cell carcinoma in the general population. Successful renal transplant probably decreases the risk of renal cell carcinoma in ACKD patients, but this preliminary observation needs confirmation. The development of ACKD-associated renal carcinoma is a continuous process with evolving phenotypic expression, including damaged renal tubule, simple cyst, cyst with atypical lining, adenoma, and, finally, carcinoma. The pathogenesis of this continuous process is not entirely known, but growth factor-induced compensatory growth of tubular epithelium initiated by the changes of end-stage kidney disease, and probably perpetuated by activation of proto-oncogenes, seems to be the most significant factor.

Transgenic mice carrying a PSArasT24 hybrid gene develop salivary gland and gastrointestinal tract neoplasms

BACKGROUND

Although prostate cancer is one of the most prevalent tumors in men, knowledge of its biology has been hindered by lack of animal models. We have attempted to develop a prostate cancer model utilizing transgenic mouse technology.

EXPERIMENTAL DESIGN

Two lines of transgenic mice were derived from one cell stage embryos injected with a fusion gene consisting of a mutated (codon 12) ras gene driven by the human prostate specific antigen (PSA) promoter in an attempt to target the oncogene specifically to the mouse prostate gland. Nontransgenic FVB/N mice were used as controls. The animals were sacrificed for study between 4 and 55 weeks of age.

RESULTS

All organs were normal except the salivary glands and gastrointestinal tracts, both of which developed carcinomas in animals older than 44 weeks. The salivary gland tumors were of ductal origin, exhibited a variable degree of differentiation, and were shown to contain abundant PSAras mRNA by in situ hybridization. The gastrointestinal tract tumors were undifferentiated but appeared to be of stromal origin. Both salivary gland and gastrointestinal tumors occasionally metastasized. No transgene expression could be demonstrated in the prostate gland by either reverse transcription-polymerase chain reaction or in situ hybridization.

CONCLUSIONS

Lack of transgene expression by the prostate can be explained on the basis of the apparent species specificity previously observed for PSA. Expression in salivary gland is best attributed to identity between the nucleotide sequences of the PSA promoter and of a mouse glandular kallikrein normally secreted by the salivary gland.

Cardiac sympathetic-parasympathetic balance in rats with experimentally-induced acute chagasic myocarditis

To clarify the mechanism responsible for the transient sinus tachycardia in rats with acute chagasic myocarditis, we have examined the cardiac sympathetic-parasympathetic balance of 29 rats inoculated with 200,000 parasites (Trypanosoma cruzi). Sixteen infected animals and 8 controls were studied between days 18 and 21 after inoculation (acute stage). The remaining 13 infected animals and 9 controls were studied between days 60 and 70 after inoculation (sub-acute stage). Under anesthesia (urethane 1.25 g/kg), all animals received intravenous atenolol (5 mg/kg) and atropine (10 mg/kg). Acute stage: The baseline heart rate of the infected animals was significantly higher than that of the controls (P < 0.0001). The magnitude of the negative chronotropic response to atenolol was 4 times that of the controls (P < 0.00001). This response correlated with the baseline heart rate (r = -0.72, P < 0.001). The heart rate responses to the beta-blocker and to atropine, of the infected animals studied during the sub-acute stage, were not different from controls. These findings suggest that cardiac sympathetic activity is transiently enhanced and cardiac parasympathetic activity is not impaired, in rats with acute chagasic myocarditis. The transient predominance of cardiac sympathetic activity could explain, in part, the sinus tachycardia observed in the acute stage of experimentally-induced chagasic myocarditis.

Type VI RNA is the major gamma-glutamyl transpeptidase RNA in the mouse small intestine

Mouse gamma-glutamyl transpeptidase (gamma GT) is encoded by a single copy gene with at least five and probably six different promoters directing the transcription of six types of gamma GT RNAs. In mouse small intestine, only Type I, V, and VI gamma GT RNAs are detected, and ribonuclease protection assays reveal that Type VI represents more than 90% of gamma GT RNA. To investigate the structure of intestinal gamma GT RNA in greater detail, we cloned and sequenced mouse intestinal gamma GT cDNAs. Seven of eight informative clones were Type VI and consisted of Type VI unique exons, VIa and VIb (as described previously by us) (Rajagopalan, S., Wan, D.-F., Habib, G. M., Sepulveda, A. R., McLeod, M. R., Lebovitz, R. M., and Lieberman, M. W. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 6179-6183) as well as common 3' sequences. Exon VIb contains two alternative splice acceptors, one previously identified by us and the other 17 bases 5' of this site. Another clone contained a previously unidentified gamma GT mRNA designated as Type VII. Type VII consists of a unique 5' exon which is 315 base pairs upstream of the exon VIa splice donor site and is spliced to exon VIb. Regulation of gamma GT expression in the small intestine is complex and involves at least three previously described promoters, alternative splicing, and a previously undescribed exonic sequence (Type VII RNA) 5' of promoter VI.

The rat probasin gene promoter directs hormonally and developmentally regulated expression of a heterologous gene specifically to the prostate in transgenic mice

An expression cassette carrying 426 basepairs of the rat probasin (PB) gene promoter and 28 basepairs of 5'-untranslated region is sufficient to target the expression of the bacterial chloramphenicol acetyltransferase (CAT) gene specifically to the prostate in transgenic mice. The PB-CAT transgene was expressed in three of five (60%) independent lines of mice, and this expression, as reported previously for the endogenous rat gene, was male specific, restricted primarily to the lateral, dorsal, and ventral lobes of the prostate, with only very low levels of CAT activity detected in the anterior prostate and seminal vesicles. The developmental and hormonal regulation of the transgene also paralleled that reported for the rat gene, with a 70-fold increase in CAT activity in the mouse prostate observed between 2-7 weeks of age, a time corresponding to sexual maturation. PB-CAT activity in the prostate declined after castration to 3.5% of the precastration level, and the CAT activity in castrated males approached precastration levels when mice were supplemented with testosterone. Transgene expression in castrated males was not induced by dexamethasone. Coinjection of PB-CAT with a chicken lysozyme gene matrix attachment region resulted in their cointegration and further restricted the pattern of PB-CAT to the dorsolateral prostate, with suppressed expression observed in the ventral prostate. These studies demonstrate that a minimal rat probasin promoter can target heterologous gene expression specifically to the prostate in a developmentally and hormonally regulated fashion.

Apical left ventricular aneurysms and cardiac parasympathetic innervation in Chagas' heart disease

Left ventricular apical aneurysms are present in Chagasic patients who have normal cardiac parasympathetic innervation. Cardiac parasympathetic abnormalities are found, in later stages of the disease, when diffuse myocardial damage and ventricular dilatation are already present. The apical region of the left ventricle is also affected in several acute and chronic non-Chagasic cardiac diseases. Therefore, thinning of the left ventricular apex, with aneurysm formation, may be a non-specific myocardial sequelae, secondary to myocardial damage.

Tenascin is an important component of the glomerular extracellular matrix in normal and pathologic conditions

Tenascin (TN), a large oligomeric glycoprotein, is a recently described component of the extracellular matrix (ECM). Previous reports focusing largely on the role of TN in nephrogenesis have documented the strong expression of TN in embryonic kidney tissue and implied an important role for TN in nephrogenesis. However, the expression of TN in normal and pathologic kidneys in adults has not been systematically evaluated. In this study immunohistochemical staining for TN was applied to 184 renal specimens diagnosed as: normal kidney (23 cases); minimal change disease and its variants (8); mesangial proliferative glomerulonephritis (GN) including IgA nephropathy and mesangial proliferative lupus nephritis (9); endocapillary proliferative GN including membranoproliferative GN, lupus nephritis, and post-infectious GN (25); crescentic GN (11); membranous GN (19); focal segmental sclerosis (15); thrombotic microangiopathy (8); amyloidosis (5); diabetic nephropathy (9); primary tubulointerstitial nephritis (14); transplant rejection (14); and ischemia (24). It was found that: (a) there was unequivocal global diffuse staining limited to the mesangium in normal kidney; (b) regardless of the etiologies and the morphologic types of glomerular disease, whenever there was expansion of the ECM, whether in the mesangial, endocapillary, or extracapillary spaces, there was a concomitant and proportional in situ increase in the TN staining; (c) globally sclerotic glomeruli, regardless of causes, showed diffuse, strong staining, especially in the subcapsular fibrous deposition seen in ischemic sclerosis; (d) non-sclerotic glomeruli showing early ischemic change uniformly displayed a marked decrease or complete loss of staining; (e) in cases of thrombotic microangiopathy, there was segmental or global staining of the capillary wall, probably corresponding to the enlarged lamina rara interna; (f) all nodular lesions in diabetic glomerulosclerosis showed strong staining, but in several of them this staining was much more pronounced in the periphery than in the center of the lesion. Our study proves that TN is probably a component of the normal mesangial matrix, that TN is an ubiquitous component of the expanded glomerular ECM in pathologic conditions regardless of morphologic subtypes, and that further studies on the cell types and mechanisms responsible for TN synthesis may provide a new venue for the understanding of the process of glomerular sclerosis.

Expression of the rasT24 oncogene in the ciliary body pigment epithelium and retinal pigment epithelium results in hyperplasia, adenoma, and adenocarcinoma

We examined eye lesions in five lines of transgenic mice carrying the human rasT24 oncogene driven by the type I gamma glutamyl transferase (gamma GT) promoter. In three lines, hyperplasia developed as early as 11.5 days postconception in the outer neuroectodermal layer, which gives rise to ciliary body and retinal pigment epithelium. At birth, the eyes from many animals contained adenomas, and by day 27, mice developed invasive adenocarcinomas originating in the region of the ciliary body. Microphthalmia, cataracts, and chronic nongranulomatous inflammation involving the anterior and/or posterior segments of the eye were also found. gamma GT is detectable histochemically as early as 11.5 gestational days in the outer neuroectodermal layer and after birth is more abundant in the ciliary body than in the retinal pigment epithelium. Using a reverse transcriptase-polymerase chain reaction, we found that type I (but not types II or III) gamma GT RNA is made by the mouse eye; the gamma GT(I)rasT24 transgene transcription product was detected in the eyes of all five transgenic lines. The sequential progression of hyperplasia to invasive neoplasms in the ciliary body in response to gamma GT(I)rasT24 expression differs from the process in the kidney of these animals in which tubular hyperplasia and microadenomas with little evidence of progression are the major lesions.

Targeting of the rasT24 oncogene to the proximal convoluted tubules in transgenic mice results in hyperplasia and polycystic kidneys

Five families of transgenic mice were derived from one-cell-stage embryos injected with gamma GT-rasT24, a fusion gene consisting of the gamma-glutamyl transpeptidase (gamma GT) 5' flanking region containing promoter I linked to a mutated (codon 12) human H-ras oncogene. The transgene was expressed selectively in the kidneys, eyes, and brains of all families as determined by reverse transcription-polymerase chain reaction, nuclease protection assays, and in situ hybridization. In two of five families, kidney lesions consisting of proximal tubular hyperplasia, renal cysts, and microadenomas developed in male animals; males also expressed higher levels of gamma GT/rasT24 RNA. Early lesions consisted of proximal tubular hyperplasia as defined by alkaline phosphatase histochemistry, gamma GT immunohistochemistry, and electron microscopy and could be correlated with the presence of rasT24 RNA within the cystic proximal tubular epithelium by in situ hybridization. Advanced lesions also involved other segments of the nephron and consisted of cysts lined by a flattened unicellular layer of attenuated epithelium. No rasT24 could be identified within cystic lesions of the distal nephron and collecting tubules by in situ hybridization, and they most likely arise by external compression. Animals from the two transgenic strains exhibiting cystic lesions die of renal failure beginning at 8 months of age. No difference in cell-cycle parameters or DNA ploidy between transgenic and control kidneys was identified by flow cytometric analysis. No renal carcinomas developed. The primary renal effects of the H-rasT24 oncogene in this model system consist of proximal tubular hyperplasia and polycystic kidneys. This model appears to provide a useful in vivo system for the study of ras oncogene function and control of renal cell proliferation.

Pulmonary arterial hypertension and cor pulmonale associated with chronic domestic woodsmoke inhalation

We describe the clinical, radiologic, functional, and pulmonary hemodynamic characteristics of a group of 30 nonsmoking patients with a lung disease that may be related to intense, long-standing indoor wood-smoke exposure. The endoscopic and some of the pathologic findings are also presented. Intense and prolonged wood-smoke inhalation may produce a chronic pulmonary disease that is similar in many aspects to other forms of inorganic dust-exposure interstitial lung disease. It affects mostly country women in their 60s, and severe dyspnea and cough are the outstanding complaints. The chest roentgenograms show a diffuse, bilateral, reticulonodular pattern, combined with normalized or hyperinflated lungs, as well as indirect signs of pulmonary arterial hypertension (PAH). On the pulmonary function test the patients show a mixed restrictive-obstructive pattern with severe hypoxemia and variable degrees of hypercapnia. Endoscopic findings are those of acute and chronic bronchitis and intense anthracotic staining of the airways appears to be quite characteristic. Fibrous and inflammatory focal thickening of the alveolar septa as well as diffuse parenchymal anthracotic deposits are the most prominent pathologic findings, although inflammatory changes of the bronchial epithelium are also present. The patients had severe PAH in which, as in other chronic lung diseases, chronic alveolar hypoxia may play the main pathogenetic role. However, PAH in wood-smoke inhalation-associated lung disease (WSIALD) appears to be more severe than in other forms of interstitial lung disease and tobacco-related COPD. The patients we studied are a selected group and they may represent one end of the spectrum of the WSIALD.

[Analysis of rheumatic valvulopathy with scanning electron microscopy]

There is a high incidence of rheumatic endocarditis in our environment. Therefore it is important to know the structural characteristics of the valvular lesions in order to better understand the physiopathologic pathways of tissue injury. We have chosen a non-conventional method, the scanning electron microscopy. There were very few such reports in the current literature. We analyzed ten mitral valve with rheumatic scarring lesion and five normal, as a control group. We were able to establish three structural patterns. 1) Stone pavement like (endocardium with nuclear bulge cells and marginal folds at the cell boundaries, abundant number of microvillous projections and few areas of endothelial loosening). 2) Cerebroid (subendothelium with wrinkles caused by deformity of the valve with or without endothelial loosening) and 3) Smooth pattern (flattened endothelium with scanty microvillous projections and abundant areas of endothelial denundation and exposition of subendothelium). More damage was noted in the auricular surface of the rheumatic group, characterized by a predominance of the smooth pattern. We found Lambl's excrecences in two mitral leaflets, they were formed by collagen break fascicles of the subendothelium. This technique allowed us to analyze integrity of the endocardial selective barrier and the interactions between the damaged surface of the valve and elements of the peripheral blood and showed more endocardial injury in the rheumatic group. These alterations could play an important role in the pathogenesis of this disease.

[Colonic polyps: an analysis of the endoscopic and histopathological aspects]

The present study is a retrospective analysis of the endoscopic and histologic features of 728 polyps resected from 422 patients during the years 1980 to 1991. Mean age of the patients was 52 years (5 to 87), 63% male and 37% female. The histology of the lesions showed: adenoma: 60.3%, hyperplastic: 31.7; juvenile: 2.3% and miscellaneous: 5.7%. The 439 adenomas where found in 270 patients of which 151 (55.9%) were male and 119 (44.1%) female. The 231 hyperplastic polyps where found in 113 patients: 66 (58.4) male and 47 (41.6) female. All the hyperplastic polyps where less than 20 mm in diameter. Of the adenomas, 385 (87.7%) where less than 20 mm in diameter and had macroscopic appearance similar to the hyperplastic polyps. Of the 439 adenomas, 218 (49.6) where pediculated and 221 (50.4%) sessile. Of the hyperplastic polyps 53 (22.9%) where pediculated and 178 (77%) sessile. Of the adenomas, 351 (80%) where tubular and 88 (22%) had a villous component, most of the tubular adenomas where less than 15 mm in diameter and the villous component was more frequent as the polyps increased in size. Of the adenomas, 139 (30%) had dysplasia and of these 10% had cancer which represents a total of 3% of all the adenomas in this series. The grade of dysplasia was more severe as the adenomas was larger in size or had villous component. The polyps were located: 69.6 in the distal colon at the reach of the flexible sigmoidoscope and 30.4% in the proximal colon.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of hydralazine on vascular mechanics in a canine lobar preparation of pulmonary embolism

We studied the effect of hydralazine (H) on pulmonary vascular mechanics in an isolated, in situ, canine lobe model of normal and increased pulmonary vascular resistance (Rp) produced by Gelfoam embolization (GE). Pulmonary pressure-flow (P-Q) curves from 24 lobes were obtained at baseline and after each intervention. Hemodynamic parameters for analysis included: the mean critical closing pressure (Ppai), vascular conductance (1/Rp), lobar flow (QL), and the pulmonary inflow pressure (Ppa) at different levels (50, 100, 200, 400, and 600 ml/min) of a fixed flow. After the preparation was stabilized, the 24 lobes were classified into 2 groups. For group 1 (n = 8) we studied the effect of H on the normal pulmonary vasculature. In group 2 (n = 16) we studied the effect of GE. Following GE, this group was further divided in half. For group 2A (n = 8) we followed the natural history of GE with measurements at 15 and 60 min. For group 2B (n = 8) measurements were done 15 min after GE and repeated again 15 min after the infusion of H. For group 1 lobes, H promoted a significant decrease (p less than 0.001) in Ppa at fixed flows of 200, 400, and 600 ml/min compared to baseline, with no change in Ppa for flows below 100 ml/min. QL and 1/Rp increased (p less than 0.01), and there was not any significant change in Ppai. In group 2A lobes, GE produced an increase in Ppa at all levels of flow (p less than 0.01), QL and 1/Rp decreased (p less than 0.05), and there was an increase in Ppai (p less than 0.05). These changes remained stable over the 60 min of observation. For group 2B lobes, GE produced the same hemodynamic changes as in group 2A, and the infusion of H caused a decrease in Ppa at flows between 100 and 300 ml/min. (p less than 0.01) with no change in Ppa at flows below 100 ml/min. QL and 1/Rp increased (p less than 0.01) and Ppai did not change compared to 15 min after GE. We conclude that in the normal canine pulmonary vasculature as well as in the model of GE, H decreased Rp and did not affect mean critical closing pressure, all of which may be explained by an increase in vascular conductance due to an increase in vascular distensibility.

Entamoeba histolytica: microtubule movement during mitosis

The movement of microtubules (MTs) during nuclear division of Entamoeba histolytica was ultrastructurally studied. Regarding this MT movement, five stages of mitosis could be defined: prophase, metaphase, anaphase A, anaphase B, and telophase. In early stages of mitosis, chromatinic material appeared condensed, and MTs were detected in the center of the nucleus. Later, MTs seemed to grow from an electron-dense body located in the center of the nucleus. This body might be the microtubule organizing center, which organized the MTs, first in a lateral way, and later to form the mitotic spindle, which was made of a bundle of MTs joined by their ends. This junction of MTs to themselves could also be observed in cross-sections. The last stage of mitosis was the nuclear separation. Two different morphological types of intranuclear vesicles were also observed, which seemed to have different types of membrane. Both intranuclear vesicles were present during nuclear division, generally in clusters, and located close to the nuclear periphery.

[Multi-technical management of biliary fistula]

Biliary fistula is an occasional complication of cholecystectomy and are usually associated to retained biliary stones, surgical trauma of the biliary ducts and local infection. They were mainly treated by surgical methods up to the acquisition of the new endoscopic and percutaneous techniques used together with parenteral and enteral nutrition and new antibiotics. A total of seven patients with diagnosis of biliary fistula were seen between 1984 and 1990 at the "Unidad de Gastroenterología y Cirugía Digestiva" of the Clínica Sanatrix en Caracas. Average age was 50 with ranged between 31 and 76, 4 were male and 3 female. The fistulas were in 1 due to necrotizing pancreatitis, in 3 to lost of the ligation of the cystic duct, 2 were due to accidental injury of the common duct and the last case was a partial dehiscence of a choledoco-jejunostomy after the resection of a common duct cyst. Four of the cases were choledoco-cutaneous fistula, one hepatocutaneous, two hepatoduodenal. All the seven patients had subhepatic collections, one had a retroperitoneal collection, two had subdiaphragmatic collections and one had multiple hepatic abscesses. The abdominal collections were treated by percutaneous drainage using mainly the Ring-McLean and Van Sonnenberg tubes. The fistula was occluded with biliary prosthesis in four cases, using either endoscopic, percutaneous or mixed technique to place the stent. Patency of the stents ranged between 2 weeks and 24 months. Control time was from 2 to 40 months.(ABSTRACT TRUNCATED AT 250 WORDS)