Immunohistochemical analysis on potential new molecular targets for esophageal cancer.

Despite multimodal therapeutic options, esophageal cancer is still among the most deadly malignancies. In the past decade, targeted therapy has shown great potential in other cancers, but data on esophageal carcinoma are still rare. Five potential new molecular targets in esophageal adenocarcinoma (EAC) and esophageal squamous cell carcinoma (ESCC) were investigated for their expression characteristics: vascular endothelial growth factor receptor (VEGFR)-3, human epidermal growth factor receptor-2, stem cell growth factor receptor, tissue inhibitors of metalloproteinase (TIMP)-4 and TIMP-3. One hundred seventy-one EAC and ESCC tissue samples obtained from patients undergoing esophagectomy from 2000 to 2008 were included. Clinical data were evaluated retrospectively. Immunohistochemical staining was performed using tumor tissue with and without neoadjuvant treatment and healthy tissue. For samples without neoadjuvant treatment, expression of all targets was higher in tumor tissue than in healthy tissue except for VEGFR-3 (>98% expression in both tissues). For TIMP-4, TIMP-3 and stem cell growth factor receptor, trends to higher expression in tumor tissue were also found in EAC and ESCC that had received neoadjuvant treatment. Using Matched-pair analysis, we compared target expression in tumor tissue with and without neoadjuvant treatment. Only TIMP-3 had significantly lower expression in neoadjuvant treated tumor tissue (EAC: P = 0.059, ESCC: P = 0.006). TIMP-4, TIMP-3 and VEGFR-3 appear to qualify for targeted therapy in esophageal cancer because of their high expression in neoplastic tissue. TIMP-3 appears to be downregulated in neoadjuvantly treated esophageal cancer, and VEGFR-3 shows high expression in healthy mucosa leading to severe side effects by molecular targeting. Thus, TIMP-4 seems the most promising target.

Tubular signal for the renin activity in the juxtaglomerular apparatus.

To investigate the effect of ionic composition of the tubular fluid in the macula densa segment upon the JGA renin activity, the macula densa segment was perfused with different solutions and the renin activity in the attached juxtaglomerular apparatus was measured. Increasing the sodium chloride concentration at the macula densa by perfusion with Ringer's solution or saline increased the JGA renin activity. An activation of JGA renin activity did not occur when amiloride was added to the saline or when the animals were pretreated by a high-salt diet. Perfusing the macula densa segment with a sodium-chloride-free solution, with sodium- or chloride-substituted solutions, or with mock early distal fluid, did not affect the JGA renin activity. These data are in accord with the proposition that in the tubuloglomerular feedback mechanism the renin-angiotensin salt diet. Perfusing the macula densa segment with a sodium-chloride-free solution, with sodium- or chloride-substituted solutions, or with mock early distal fluid, did not affect the JGA renin activity. These data are in accord with the proposition that in the tubuloglomerular feedback mechanism the renin-angiotensin salt diet. Perfusing the macula densa segment with a sodium-chloride-free solution, with sodium- or chloride-substituted solutions, or with mock early distal fluid, did not affect the JGA renin activity. These data are in accord with the proposition that in the tubuloglomerular feedback mechanism the renin-angiotensin system in the juxtaglomerular apparatus acts as a local, humoral mediator between the signal perceived at the macula densa and the hemodynamic response at the glomerulus. The mediation by the renin-angiotensin system, which is influenced by the sodium chloride balance, allows the sensitivity of this control of GFR to be adjusted in a homeostatically appropriate manner.

Glomerulus number and blood pressure in the Prague hypertensive rat.

The kidney has long been attributed a key role in the pathogenesis of hypertension. Reduction of filtration area by glomerular loss is regarded currently as a major causative mechanism. Here we analyze the relationship between glomerulus number and blood pressure (BP) in a new model of genetic hypertension and the Prague hypertensive rat (PHR) and the Prague normotensive rat (PNR). Glomerular numbers were determined in 7- to 53-week-old PNR and PHR, and the correlation with conscious systolic BP was analyzed. PHR had significantly higher BP but 19% fewer glomeruli than PNR. Glomerular number correlated (partial correlation analysis, controlling for effects of body weight, age, and kidney weight) significantly (P < 0.01, r2 = 0.46) with BP in male PHR but not in female PHR or in PNR. Moreover, subgroups of PHR and PNR selected for the same mean BP showed the same differences in glomerular counts, and subgroups selected for the same mean glomerular count showed the same differences in BP as the whole group. Reduced glomerular numbers and BP seem not to be causally related to BP in PHR older than seven weeks. Other mechanisms, such as genetically determined changes in transporter and receptor proteins, vascular abnormalities, and humoral mechanisms, must be considered.

A transient role of the kidney in the maintenance of hypertension.

Using the Prague hypertensive rat (PHR), a model derived from the Wistar rat, in which a normotensive parallel, the Prague normotensive rat (PNR), was bred from the same parent pair (so that transplantation of organs between both these parallel rat model lines results in no distinct signs of rejection), we were able to show that hypertension travels with the kidney. Transplantation of a kidney from PHR to a bilaterally nephrectomized (BNX) PNR led to an increase in systolic blood pressure (SBP) in the recipient for 10 weeks after grafting. Similarly, a decrease in SBP was seen in BNX PHR for the same period of time after grafting a kidney from PNR. If, however, the SBP was measured over a longer period of time, because the elevated SBP slowly drops after grafting a kidney from PHR to BNX PNR, it is less than 130 mm Hg in the fourth month and thereafter. If BNX PHR receives a kidney from PNR, the decrease in SBP is permanent, amounting to 126.3 +/- 12.7 mm Hg one year after transplantation. The grafting of a heart from PHR to the abdominal aorta of PNR does not influence SBP. In conclusion, the presence of a kidney from PHR is necessary for the development, but is not sufficient for the maintenance of hypertension. The heart of PHR is not "hypertensogenic" as is the kidney.

Ketoconazole inhibits organic osmolyte efflux and induces heat shock proteins in rat renal medulla.

Although ketoconazole (KC) is known to inhibit the cellular efflux of organic osmolytes in vitro, it is not known whether this effect can also be shown in vivo. Inhibition of osmolyte efflux by KC would impair osmotic adaptation and result in stress to the cells of the renal medulla when extracellular osmolality falls. Stress-inducible heat shock proteins (HSPs) may also participate in this response to osmotic stress. The aim of the present study was thus to establish whether KC inhibits organic osmolyte efflux from the cells of the renal medulla in vivo in response to a furosemide diuresis, and to establish whether HSPs are involved. A 20-minute furosemide infusion reduced urine osmolality and medullary urea content in control and KC-treated rats similarly. However, the efflux of methylamines (glycerophosphorylcholine, betaine) and polyols (myo-inositol, sorbitol) was attenuated in KC-treated rats while the efflux of amino acids was not significantly affected. Phosphorylation of HSP25 after the 20-minute furosemide diuresis was increased in KC rats. With continuing diuresis this returned to control levels after three hours. While short-term (up to 3 hr) diuresis did not alter the absolute amounts of HSPs in the renal medulla, long-term (24 or 48 hr) diuresis was associated with significantly increased amounts of HSP25 and HSP72 in KC-treated rats compared with control. These results suggest that KC inhibits the efflux of methylamines and polyols, thus impeding osmoadaptation of renal medullary cells during the onset of diuresis. This situation apparently increases the osmotic stress experienced by the cells of the renal medulla and provokes expression of HSP25 and HSP72.

Electron microprobe analysis of chloride secretion in the frog cornea.

Electron microprobe analysis was employed to measure the intracellular electrolyte concentrations of the bullfrog corneal epithelium. Under control conditions, transepithelial potential short-circuited and both sides of the isolated cornea incubated in Conway's solution, the mean intracellular concentrations were 8.0 for sodium, 18.4 for chloride and 117.3 for potassium (mmole/kg wet weight). These values are in good agreement with previously reported ion activities implying that the intracellular activity co-efficient for small ions is close to that of the extracellular space. No significant differences between the nuclear and cytoplasmic concentrations of small diffusible ions were detectable. Similarly, the chloride concentrations in the different epithelial layers were virtually identical and showed parallel changes at varying states of chloride secretion, suggesting that corneal epithelium represents a functional syncytium. The behavior of the intracellular ion concentrations after removal of sodium, chloride or potassium from the outer or inner bath is consistent with a passive electrodiffusive efflux of chloride across the outer membrane and a sodium coupled chloride uptake across the inner membrane. Furthermore, effects of bicarbonate and CO2 on the rate of chloride secretion and on the intracellular sodium and chloride concentrations were observed, indicating a possible role of pH in regulating chloride secretion.

Tracing the Na/K-ATPase with rubidium.

Rubidium (Rb) was used as a marker ion for K to assess Na/K(Rb)-ATPase activity in single renal tubule cells. Initial Rb uptake rates were measured by electron microprobe analysis in individual tubule cells of the rat kidney during acute stimulation or during inhibition of transepithelial Na absorption. Under these conditions, Rb uptake closely correlates with intracellular Na concentrations, indicating that the intracellular Na concentration is a major determinant in the precise adjustment of basolateral, Na/K(Rb)-ATPase-dependent Na extrusion to Na entry across the apical cell membrane. Chronically increased distal Na delivery induced by loop diuretics triggers adaptive processes which allow increased transcellular Na movement at normal or near-normal intracellular Na concentrations.

Sodium and potassium concentrations of renal cortical cells two animal models of primary arterial hypertension.

Electron microprobe analysis was used to determine cellular concentrations of potassium and sodium in renal cortical cells of hypertensive rats of the Milan strain (MHS) and spontaneously hypertensive rats of the stroke prone strain (SHRSP) and their respective controls. Potassium concentrations in proximal and distal tubular cells were similar in both strains of hypertensive rats compared with their normotensive controls. In MHS rats proximal tubular cell sodium concentration was lower than in controls by 3.1 mmol/kg ww, whereas in both proximal and distal tubular cells of SHRSP sodium concentrations were higher than in controls by 5.3 and 4.3 mmol/kg ww, respectively. These results indicate that changes in the transport characteristics of the renal tubular epithelium are a feature of both models of hypertension.