Astrochemical relevance of VUV ionization of large PAH cations. Astron Astrophys 2020;641:A98. [PMID: 33154599 PMCID: PMC7116310 DOI: 10.1051/0004-6361/202038139]

CONTEXT

As a part of interstellar dust, polycyclic aromatic hydrocarbons (PAHs) are processed by the interaction with vacuum ultra-violet (VUV) photons that are emitted by hot young stars. This interaction leads to the emission of the well-known aromatic infrared bands but also of electrons, which can significantly contribute to the heating of the interstellar gas.

AIMS

Our aim is to investigate the impact of molecular size on the photoionization properties of cationic PAHs.

METHODS

Trapped PAH cations of sizes between 30 and 48 carbon atoms were submitted to VUV photons in the range of 9 to 20 eV from the DESIRS beamline at the synchrotron SOLEIL. All resulting photoproducts including dications and fragment cations were mass-analyzed and recorded as a function of photon energy.

RESULTS

Photoionization is found to be predominant over dissociation at all energies, which differs from an earlier study on smaller PAHs. The photoionization branching ratio reaches 0.98 at 20 eV for the largest studied PAH. The photoionization threshold is observed to be between 9.1 and 10.2 eV, in agreement with the evolution of the ionization potential with size. Ionization cross sections were indirectly obtained and photoionization yields extracted from their ratio with theoretical photoabsorption cross sections, which were calculated using time-dependent density functional theory. An analytical function was derived to calculate this yield for a given molecular size.

CONCLUSIONS

Large PAH cations could be efficiently ionized in H i regions and provide a contribution to the heating of the gas by photoelectric effect. Also, at the border of or in H ii regions, PAHs could be exposed to photons of energy higher than 13.6 eV. Our work provides recipes to be used in astronomical models to quantify these points.

Control of the mobilization of arsenic and other natural pollutants in groundwater by calcium carbonate concretions in the Pampean Aquifer, southeast of the Buenos Aires province, Argentina

The water supply for human consumption in the Chaco-Pampean region in Argentina is restricted by the low quality of groundwater due to elevated concentrations of arsenic and other trace elements. Previous studies indicated a complex concurrence of factors and processes that are believed responsible to control the distribution of arsenic in groundwater. For a better understanding of the origin of trace elements in the Pampean aquifer, flow-through experiments with loess and calcrete samples representative of the sediments that constitute the aquifer were carried out in continuous flow reactors. The aqueous solutions were collected and the concentrations of SiO₂(aq), Ca²⁺, SO₄^2-, Na⁺, Cl^-, F^- and trace elements (Ba, Sr, V, and As) were measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), high performance liquid chromatography (HPLC) and capillary electrophoresis. The experiments showed differences in the release rate of elements to the solution according to the type of sediment. The highest concentrations of V, Ba, and As were measured in experiments conducted with loess, and these elements were released quickly to the solution in the first minute of the test. In the case of loess, V and As are suggested to be adsorbed on the solid particles surface. Conversely, the experiments conducted with calcrete showed a lower but continuous release of those elements. This last result may indicate that the trace elements were coprecipitated in the calcite. In addition, it was demonstrated that F did not come from the dissolution of minerals such as fluorapatite, but both desorption from solid surface and dissolution from calcite minerals account for the release of F. This study support that both dissolution and adsorption-desorption processes can control the mobility of trace elements, with an emphasis on the role of calcrete in the retention and the mobilization of trace elements in the Pampean aquifer.

Microwave-induced covalent functionalization of few-layer graphene with arynes under solvent-free conditions

A non-conventional modification of exfoliated few-layer graphene (FLG) with different arynes under microwave (MW) irradiation and solvent-free conditions is reported. The described approach allows reaching fast, efficient and mild covalent functionalization of FLG.

Invasive rainbow trout Oncorhynchus mykiss preying on the endangered naked characin Gymnocharacinus bergii at its thermal limits

The expansion of the invasive rainbow trout Oncorhynchus mykiss into the thermal headwaters of Valcheta Stream (Patagonia, Argentina) and new predation records on the endangered endemic naked characin Gymnocharacinus bergii are presented here. These findings are discussed in relation to the contemporary evolution and thermal refuges hypothesis. This study has immediate implications for the conservation of G. bergii.

Colonic content in health and its relation to functional gut symptoms

BACKGROUND

Gut content may be determinant in the generation of digestive symptoms, particularly in patients with impaired gut function and hypersensitivity. Since the relation of intraluminal gas to symptoms is only partial, we hypothesized that non-gaseous component may play a decisive role.

METHODS

Abdominal computed tomography scans were evaluated in healthy subjects during fasting and after a meal (n = 15) and in patients with functional gut disorders during basal conditions (when they were feeling well) and during an episode of abdominal distension (n = 15). Colonic content and distribution were measured by an original analysis program.

KEY RESULTS

In healthy subjects both gaseous (87 ± 24 mL) and non-gaseous colonic content (714 ± 34 mL) were uniformly distributed along the colon. In the early postprandial period gas volume increased (by 46 ± 23 mL), but non-gaseous content did not, although a partial caudad displacement from the descending to the pelvic colon was observed. No differences in colonic content were detected between patients and healthy subjects. Symptoms were associated with discrete increments in gas volume. However, no consistent differences in non-gaseous content were detected in patients between asymptomatic periods and during episodes of abdominal distension.

CONCLUSIONS & INFERENCES

In patients with functional gut disorders, abdominal distension is not related to changes in non-gaseous colonic content. Hence, other factors, such as intestinal hypersensitivity and poor tolerance of small increases in luminal gas may be involved.

Intestinal gas content and distribution in health and in patients with functional gut symptoms

BACKGROUND

The precise relation of intestinal gas to symptoms, particularly abdominal bloating and distension remains incompletely elucidated. Our aim was to define the normal values of intestinal gas volume and distribution and to identify abnormalities in relation to functional-type symptoms.

METHODS

Abdominal computed tomography scans were evaluated in healthy subjects (n = 37) and in patients in three conditions: basal (when they were feeling well; n = 88), during an episode of abdominal distension (n = 82) and after a challenge diet (n = 24). Intestinal gas content and distribution were measured by an original analysis program. Identification of patients outside the normal range was performed by machine learning techniques (one-class classifier). Results are expressed as median (IQR) or mean ± SE, as appropriate.

KEY RESULTS

In healthy subjects the gut contained 95 (71, 141) mL gas distributed along the entire lumen. No differences were detected between patients studied under asymptomatic basal conditions and healthy subjects. However, either during a spontaneous bloating episode or once challenged with a flatulogenic diet, luminal gas was found to be increased and/or abnormally distributed in about one-fourth of the patients. These patients detected outside the normal range by the classifier exhibited a significantly greater number of abnormal features than those within the normal range (3.7 ± 0.4 vs 0.4 ± 0.1; p < 0.001).

CONCLUSIONS & INFERENCES

The analysis of a large cohort of subjects using original techniques provides unique and heretofore unavailable information on the volume and distribution of intestinal gas in normal conditions and in relation to functional gastrointestinal symptoms.

Mechanisms of abdominal distension in severe intestinal dysmotility: abdomino-thoracic response to gut retention

BACKGROUND

We previously showed that abdominal distension in patients with functional gut disorders is due to a paradoxical diaphragmatic contraction without major increment in intraabdominal volume. Our aim was to characterize the pattern of gas retention and the abdomino-thoracic mechanics associated with abdominal distension in patients with intestinal dysmotility.

METHODS

In 15 patients with manometrically proven intestinal dysmotility, two abdominal CT scans were performed: one during basal conditions and other during an episode of severe abdominal distension. In 15 gender- and age-matched healthy controls, a basal scan was performed.

KEY RESULTS

In basal conditions, patients exhibited more abdominal gas than healthy subjects, particularly in the small bowel, and the volume significantly increased during an episode of distension. During episodes of abdominal distension, the increase in abdominal content was associated with increased girth and antero-posterior abdominal diameter, as well as a cephalic displacement of the diaphragm, which reduced the height of the lung. The consequent reduction in the air volume of the lung was attenuated by an increase in the antero-posterior diameter of the chest.

CONCLUSIONS & INFERENCES

Abdominal distension in patients with severe intestinal dysfunction is related to marked pooling of gut contents, particularly in the small bowel. This increase in content is accommodated within the abdominal cavity by a global and coordinated abdomino-phreno-thoracic response, involving an accommodative ascent of the diaphragm and a compensatory expansion of the chest wall.

Use of a prosthetic mesh to prevent parastomal hernia during laparoscopic abdominoperineal resection: a randomized controlled trial

PURPOSE

Prevention of parastomal hernia represents an important aim when a permanent stoma is necessary. The objective of this work is to assess whether implantation of a prophylactic prosthetic mesh during laparoscopic abdominoperineal resection contributed to reduce the incidence of parastomal hernia.

METHODS

Rectal cancer patients undergoing elective laparoscopic abdominoperineal resection with permanent colostomy were randomized to placement of a large-pore lightweight mesh in the intraperitoneal/onlay position by the laparoscopic approach (study group) or to the control group (no mesh). Parastomal hernia was defined radiologically by a CT scan performed after 12 months of surgery. The usefulness of subcutaneous fat thickness measured by CT to discriminate patients at risk of parastomal hernia was assessed by ROC curve analysis.

RESULTS

Thirty-six patients were randomized, 19 to the mesh group and 17 to the control group. Parastomal hernia was detected in 50 % of patients in the mesh group and in 93.8 % of patients in the control group (P = 0.008). The AUC for thickness of the subcutaneous abdominal was 0.819 (P = 0.004) and the optimal threshold 23 mm. Subcutaneous fat thickness ≥23 mm was a significant predictor of parastomal hernia (odds ratio 15.7, P = 0.010), whereas insertion of a mesh was a protective factor (odds ratio 0.06, P = 0.031).

CONCLUSIONS

Use of prophylactic large-pore lightweight mesh in the intraperitoneal/onlay position by a purely laparoscopic approach reduced the incidence of parastomal hernia formation. Subcutaneous fat thickness ≥23 mm measured by CT was an independent predictor of parastomal hernia.

Systematic review: the use of ultrasonography, computed tomography and magnetic resonance imaging for the diagnosis, assessment of activity and abdominal complications of Crohn's disease

BACKGROUND

Cross-sectional imaging techniques, including ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI), are increasingly used for evaluation of Crohn's disease (CD). Aim  To perform an assessment of the diagnostic accuracy of cross-sectional imaging techniques for diagnosis of CD, evaluation of disease extension and activity and diagnosis of complications, and to provide recommendations for their optimal use.

METHODS

Relevant publications were identified by literature search and selected based on predefined quality parameters, including a prospective design, sample size and reference standard. A total of 68 publications were chosen.

RESULTS

Ultrasonography is an accurate technique for diagnosis of suspected CD and for evaluation of disease activity (sensitivity 0.84, specificity 0.92), is widely available and non-invasive, but its accuracy is lower for disease proximal to the terminal ileum. MRI has a high diagnostic accuracy for the diagnosis of suspected CD and for evaluation of disease extension and activity (sensitivity 0.93, specificity 0.90), and is less dependent on the examiner and disease location compared with US. CT has a similar accuracy to MRI for assessment of disease extension and activity. The three techniques have a high accuracy for identification of fistulas, abscesses and stenosis (sensitivities and specificities >0.80), although US has false positive results for abscesses. As a result of the lack of radiation, US or MRI should be preferred over CT, particularly in young patients.

CONCLUSIONS

Cross-sectional imaging techniques have a high accuracy for evaluation of suspected and established CD, reliably measure disease severity and complications; they may offer the possibility to monitor disease progression.

The Cdk5-p35 kinase associates with the Golgi apparatus and regulates membrane traffic

We show here that an active Cdk5-p35 kinase is present in Golgi membranes, where it associates with a detergent-insoluble fraction containing actin. In addition, Cdk5-p35-dependent phosphorylation of alpha-PAK immunoreactive protein species was detected in Golgi membranes, as well as an interaction with the small GTPase, Cdc42. Moreover, antisense oligonucleotide suppression of Cdk5 or p35 in young cultured neurons, as well as inhibition of Cdk5 activity with olomoucine, blocks the formation of membrane vesicles from the Golgi apparatus. Taken together, these results show a novel subcellular localization of this kinase and suggest a role for Cdk5-p35 in membrane traffic during neuronal process outgrowth.

Usefulness of magnetic resonance spectroscopy for diagnosis of hepatic encephalopathy in a patient with relapsing confusional syndrome

Magnetic resonance spectroscopy allows the assessment of several metabolites in brain tissue. In patients with hepatic encephalopathy, this technique shows a rise in glutamine and a decrease in myoinositol in brain tissue. However, the role of magnetic resonance spectroscopy in the diagnosis of hepatic encephalopathy is not known. We report the case of a patient with a relapsing confusional syndrome who underwent magnetic resonance spectroscopy. Previously, hepatic encephalopathy was ruled out because of the negative results of a transjugular liver biopsy and normal hepatic venous pressure gradient. The results of magnetic resonance were characteristic of hepatic encephalopathy. Abdominal computed tomography demonstrated large portosystemic shunts associated with cirrhosis of the liver. This case shows that magnetic resonance spectroscopy is an useful technique for the diagnosis of hepatic encephalopathy in selected cases, such as those without clinical signs of cirrhosis and/or large portosystemic shunts.

Helical CT in renal transplantation: normal findings and early and late complications

Over a 5-year period, 346 helical computed tomographic (CT) studies were performed in renal transplant recipients. Helical CT proved useful in this context by depicting parenchymal, perirenal, renal sinus, pyeloureteral, and vascular complications in great detail. CT often delineates fluid collections and their anatomic relationship to adjacent structures better than ultrasonography (US), particularly in obese patients. CT-guided puncture and drainage can be performed in cases in which US is deemed inadequate. CT angiography can depict arterial diseases such as stenosis, thrombosis, arteriovenous fistulas, aneurysms, and pseudoaneurysms in the graft artery and in the recipient iliac arterial system, thereby obviating conventional angiography in some cases. Helical CT with three-dimensional image reformatting allows accurate imaging of the entire course of ureteral and periureteral diseases (eg, hydronephrosis, ureteral leak and stricture, pyeloureteral obstruction). CT can be used in the confirmation and staging of malignancies of the renal parenchyma and urothelium. It is also helpful in evaluating associated disease in the native kidneys, acute and chronic rejection, graft embolization, and end-stage disease. Although US and nuclear medicine examination are the imaging modalities of choice in renal transplantation, helical CT is a valuable alternative when these techniques are inconclusive.

Complications of orthotopic liver transplantation: spectrum of findings with helical CT

Orthotopic liver transplantation has become the treatment of choice for patients with end-stage nonmalignant liver disease. The surgical techniques and immunosuppressive therapy for this procedure have improved considerably. Nevertheless, there are still significant complications, particularly those of vascular origin, which can lead to graft failure and require retransplantation unless prompt treatment is instituted. These complications include arterial and venous thrombosis and stenosis; arterial pseudoaneurysm; biliary leakage, stricture, and obstruction; liver ischemia, infarction, and abscess; fluid collections and hematomas; lymphoproliferative disorders; recurrent tumors; hepatitis C virus infection; and splenic infarction. Since the clinical presentation of posttransplantation complications is frequently nonspecific and varies widely, imaging studies are critical for early diagnosis. Helical computed tomography (CT) is a valuable complement to ultrasonography (US) in the postoperative period and is a safe, accurate, and noninvasive method of demonstrating hepatic vessels (hepatic artery, portal vein, hepatic veins, and inferior vena cava) and evaluating nonvascular complications (in the hepatic parenchyma and bile duct abnormalities) and extrahepatic tissues. Knowledge and early recognition of these complications is essential for graft salvage, and CT can provide valuable information, particularly for patients with indeterminate US results or in whom US examination is difficult.

Evidence for the involvement of Tiam1 in axon formation

In cultured neurons, axon formation is preceded by the appearance in one of the multiple neurites of a large growth cone containing a labile actin network and abundant dynamic microtubules. The invasion-inducing T-lymphoma and metastasis 1 (Tiam1) protein that functions as a guanosine nucleotide exchange factor for Rac1 localizes to this neurite and its growth cone, where it associates with microtubules. Neurons overexpressing Tiam1 extend several axon-like neurites, whereas suppression of Tiam1 prevents axon formation, with most of the cells failing to undergo changes in growth cone size and in cytoskeletal organization typical of prospective axons. Cytochalasin D reverts this effect leading to multiple axon formation and penetration of microtubules within neuritic tips devoid of actin filaments. Taken together, these results suggest that by regulating growth cone actin organization and allowing microtubule invasion within selected growth cones, Tiam1 promotes axon formation and hence participates in neuronal polarization.

Hemoperitoneum as a first manifestation of hepatocellular carcinoma in western patients with liver cirrhosis: effectiveness of emergency treatment with transcatheter arterial embolization

Hemoperitoneum is a well-known form of hepatocellular carcinoma presentation and represents a frequent complication in countries with a high incidence of hepatocellular carcinoma, but it is rarely seen in Western countries. Our aim was to report the results and describe the arteriographic and CT-scan characteristics in a series of seven consecutive patients. They were admitted to our hospital because of hemoperitoneum due to ruptured tumor as a first manifestation of hepatocellular carcinoma, and the rupture was effectively controlled by transcatheter arterial embolization. From April 1989 to April 1998, 440 consecutive patients were admitted to our liver unit with the diagnosis of hepatocellular carcinoma and liver cirrhosis. Fourteen patients (3%) presented with acute hemoperitoneum due to tumor rupture as a first manifestation of hepatocellular carcinoma. We here report our experience in the group of patients treated by transcatheter arterial embolization. Mean age was 67.1+/-5 years (range, 61-73). All patients presented with sudden abdominal pain, abdominal distension, and four patients had symptoms of acute anemia. In all cases the ruptured tumor was subcapsular. The procedure was effective in the control of bleeding in all cases, without significant impairment in liver function or treatment-related deaths. In six of the seven patients, a self-limited postembolization syndrome was observed. Mean survival time was 273+/-488.7 days (range: 15-1290). Three patients survived more than six months but at the time of evaluation, only one patient was alive. In conclusion, the present results confirm that transcatheter arterial embolization is an effective and well-tolerated treatment in the management of hemoperitoneum due to ruptured hepatocellular carcinoma in patients with liver cirrhosis.

Improved diagnosis of hepatic perfusion disorders: value of hepatic arterial phase imaging during helical CT

The liver has a unique dual blood supply, which makes helical computed tomography (CT) a highly suitable technique for hepatic imaging. Helical CT allows single breath-hold scanning without motion artifacts. Because of rapid image acquisition, two-phase (hepatic arterial phase and portal venous phase) evaluation of the hepatic parenchyma is possible, improving tumor detection and tumor characterization in a single CT study. The arterial and portal venous supplies to the liver are not independent systems. There are several communications between the vessels, including transsinusoidal, transvasal, and transplexal routes. When vascular compromise occurs, there are often changes in the volume of blood flow in individual vessels and even in the direction of blood flow. These perfusion disorders can be detected with helical CT and are generally seen as an area of high attenuation on hepatic arterial phase images that returns to normal on portal venous phase images; this finding reflects increased arterial blood flow and arterioportal shunting in most cases. Familiarity with the helical CT appearances of these perfusion disorders will result in more accurate diagnosis. By recognizing these perfusion disorders, false-positive diagnosis (hypervascular tumors) or overestimation of the size of liver tumors (eg, hepatocellular carcinoma) can be avoided.

Flunitrazepam partitioning into natural membranes increases surface curvature and alters cellular morphology

In recent studies, we showed that flunitrazepam (FNTZ) and other benzodiazepines interact with artificial phospholipid membranes locating at the polar head group region, inducing a membrane expansion, reducing the molecular packing and reorganising molecular dipoles. In the present paper we investigated the possibility that those phenomena could be transduced into changes in the curvature of membranes from natural origin. Hence we studied the effect of FNTZ on cellular morphology using human erythrocyte as a natural assay system. Shape changes of erythrocytes were evaluated by light microscopy and expressed as a morphological index (MI). FNTZ induced echinocytosis in a time-dependent manner with MI values significantly higher than those of control (without drug) or DMSO (vehicle) samples. Lidocaine, a local anesthetic known to induce stomatocytosis by incorporating in the inner monolayer, counterbalanced the concentration-dependent FNTZ crenating effects. FNTZ induced protective effects, compared with control and DMSO, against time-dependent hemolysis. Hypotonic-induced hemolysis, was also lowered by FNTZ in a concentration-dependent manner. Both antihemolytic effects suggested a drug-induced membrane expansion allowing a greater increase in cell volume before lysis. In such a complex system like a cell, curvature changes triggered by drug partitioning towards the plasma membrane, might be an indirect effect exerted through modifications of ionic-gradients or by affecting cytoskeleton-membrane linkage. In spite of that, the curvature changes can be interpreted as a mechanism suitable to relieve the tension generated initially by drug incorporation into the bilayer and may be the resultant of the dynamic interactions of many molecular fluxes leading to satisfy the spontaneous membrane curvature.

Portomesenteric vein gas: pathologic mechanisms, CT findings, and prognosis

Portomesenteric vein gas is a rare condition whose pathogenesis is not fully understood. Portomesenteric vein gas is most commonly caused by mesenteric ischemia but may have a variety of other causes. The primary factors that favor the development of this pathologic entity are intestinal wall alterations, bowel distention, and sepsis. Portomesenteric vein gas is idiopathic in approximately 15% of cases. Advanced imaging techniques such as computed tomography (CT) have increased the sensitivity for detection of portomesenteric vein gas. At CT, portal vein gas appears as tubular areas of decreased attenuation in the liver, predominantly in the left lobe. Gas in the great mesenteric veins can easily be demonstrated with contrast material-enhanced CT, whereas gas in the small mesenteric veins appears as tubular or branched areas of decreased attenuation in the mesenteric border of the bowel. Findings of portomesenteric vein gas at CT should be carefully evaluated in the context of clinical findings. In the majority of cases, the prognosis is favorable and surgery is not required. However, when CT demonstrates portomesenteric vein gas and clinical findings suggest the presence of mesenteric ischemia, surgery is mandatory.

Accuracy of helical computed tomographic angiography for the diagnosis of colonic angiodysplasia

BACKGROUND & AIMS

The diagnosis of colonic angiodysplasia is often challenging and relies on endoscopy or catheter angiography. We investigated whether computed tomographic angiography (CTA) contributes to the diagnosis of colonic angiodysplasia.

METHODS

Twenty-eight patients with suspected bleeding from colonic angiodysplasia were prospectively evaluated. Gastrointestinal bleeding was investigated by colonoscopy plus visceral angiography and by CTA. The level of agreement between CTA and the former procedures was determined.

RESULTS

CTA images of diagnostic quality were obtained in 26 patients. Eighteen patients were diagnosed with colonic angiodysplasia by colonoscopy plus visceral angiography, and 14 by CTA (kappa = 0.68; P < 0.001). Sensitivity, specificity, and positive predictive values of CTA for detection of colonic angiodysplasia were 70%, 100%, and 100%, respectively. CTA signs including accumulation of vessels in the colonic wall, early filling vein, and supplying enlarged artery were present in 55%, 50%, and 22% of cases, respectively. None of these signs were present in the 8 patients with obscure gastrointestinal bleeding and negative diagnostic investigation of the digestive tract.

CONCLUSIONS

CTA is a sensitive, specific, well-tolerated, and minimally invasive tool for the diagnosis of colonic angiodysplasia.

2,4-Dichlorophenoxyacetic acid disrupts the cytoskeleton and disorganizes the Golgi apparatus of cultured neurons

2,4-Dichlorophenoxyacetic acid (2,4-D) is a potent neurotoxic herbicide widely used in agriculture. The basic mechanisms by which 2,4-D produces cell damage have not yet been determined. In this study we have examined the effects of 2,4-D in primary cultures of cerebellar granule cells in order to obtain insights into the possible mechanisms underlying the toxic effects of this herbicide. The results obtained indicate that a 24-hour exposure to 2,4-D produces a striking and dose-dependent inhibition of neurite extension. This phenomenon is paralleled by a significant reduction in the cellular content of both dynamic and stable microtubules, a disorganization of the Golgi apparatus, and an inhibition in the synthesis of complex gangliosides. Interestingly, 2,4-D inhibits the in vitro polymerization of purified tubulin. Taken together, the present observations raise the possibility that at least one basic mechanism underlying 2,4-D neurotoxicity involves an inhibition of microtubule assembly. That event may cause a decreased neurite outgrowth response, and could also explain the observed differences in the pattern of ganglioside biosynthesis and/or the disorganization of the Golgi apparatus.

Arteriovenous fistula secondary to iliac mycotic aneurysm: helical CT findings

We describe the case of a 59-year-old man who presented a mycotic aneurysm of the common right iliac artery due to Streptococcus agalactiae and developed an arteriovenous fistula within the inferior vena cava secondary to spontaneous rupture of the aneurysm. The clinical syndrome, helical computed tomographic, and angiographic findings are described and discussed.

Tau protein function in axonal formation

Tau protein is a predominantly neuronal microtubule-associated protein that is enriched in axons and is capable of promoting microtubule assembly and stabilization. In the present article we review some of the key experiments directed to obtain insights about tau protein function in developing neurons. Aspects related to whether or not tau has essential, unique, or complementary functions during axonal formation are discussed.

Intrahepatic arterioportal shunt: helical CT findings

The purpose of this study was to characterize the appearance of intrahepatic arterioportal shunts (APS) on two-phase helical CT, with emphasis on the importance of the hepatic arterial-dominant phase (HAP) to demonstrate perfusion disorders. We review eight cases of APS diagnosed by helical CT in our institution from January 1996 to March 1997 and describe the CT findings that established diagnosis. Five of them were confirmed by angiography. In seven (87. 5 %) cases of APS we found early enhancement of the peripheral portal branches during the HAP of helical CT, whereas the superior mesenteric and splenic veins remained unenhanced. In five (62.5 %) cases of APS, transient, peripheral, triangular parenchymal enhancement was depicted during the HAP of helical CT; in four of these cases there was associated early enhancement of the portal branches. Helical CT can show perfusion alterations that might remain undiagnosed with conventional CT. An understanding of the hemodynamic changes that occur in APS can help in the interpretation of focal transient hepatic parenchymal enhancement and to differentiate APS from hypervascular tumors. We believe that the helical CT findings described herein are characteristic enough to suggest the diagnosis of APS.

Renal trauma in occult ureteropelvic junction obstruction: CT findings

The aim of this study was to present CT findings of occult ureteropelvic junction obstruction in patients with renal trauma and to describe the clinical signs and singular CT features that are characteristically observed with trauma and are relevant to management of these patients. We retrospectively reviewed 82 helical CT studies in patients with renal trauma referred to our institution. We found 13 cases of occult preexisting renal pathology, six of which were occult ureteropelvic junction obstructions. The clinical presentation, radiologic findings of trauma according to the Federle classification, and CT findings of obstructed ureteropelvic junction are presented. We found three category-I lesions (one in horseshoe kidney), two of them treated with nephrostomy because of increased ureteropelvic junction obstruction due to pelvic clots; two category-II lesions (parenchymal and renal pelvis lacerations) that had presented only with microhematuria; and one category-IV lesion (pelvic laceration alone). Pelvic extension was demonstrated in all the cases with perirenal collections. The CT studies in all the cases with suspected ureteropelvic junction obstruction showed decreased parenchymal thickness and enhancement, and dilatation of the renal pelvis and calyx, with a normal ureter. Computed tomography can provide information to confidently diagnose underlying ureteropelvic junction obstruction in renal trauma, categorize the traumatic injury (at times clinically silent) and facilitate proper management according to the singularities observed, such us rupture of the renal pelvis alone (Federle category IV) and increasing ureteropelvic obstruction due to clots which can be decompressed by nephrostomy.

Aortic dissection: diagnosis and follow-up with helical CT

Acute aortic dissection is a cardiovascular emergency that requires prompt diagnosis and treatment. Helical computed tomography (CT) allows diagnosis of acute aortic dissection with a sensitivity and specificity of nearly 100%. With helical CT, a dissection involving the ascending aorta (type A in the Stanford classification) can be differentiated from one distal to the left subclavian artery (type B). Helical CT can also be used to identify atypical forms of aortic dissection such as intramural hematoma, penetrating atherosclerotic ulcer, ruptured type B dissection, and atypical configurations of the intimal flap. Helical CT is useful in follow-up of aortic dissection by allowing assessment of early and late changes after surgery or medical treatment. Such changes include postoperative complications of type A dissection, healing of intramural hematoma, progression of intramural hematoma, and aneurysms of the true or false lumen. Helical CT can also be used to monitor potentially life-threatening ischemic complications of abdominal branch vessels.

Evidence for the participation of the neuron-specific CDK5 activator P35 during laminin-enhanced axonal growth

Cultures of cerebellar macroneurons were used to study the pattern of expression, subcellular localization, and function of the neuronal cdk5 activator p35 during laminin-enhanced axonal growth. The results obtained indicate that laminin, an extracellular matrix molecule capable of selectively stimulating axonal extension and promoting MAP1B phosphorylation at a proline-directed protein kinase epitope, selectively stimulates p35 expression, increases its association with the subcortical cytoskeleton, and accelerates its redistribution to the axonal growth cones. Besides, suppression of p35, but not of a highly related isoform designated as p39, by antisense oligonucleotide treatment selectively reduces cdk5 activity, laminin-enhanced axonal elongation, and MAP1b phosphorylation. Taken collectively, the present results suggest that cdk5/p35 may serve as an important regulatory linker between environmental signals (e.g., laminin) and constituents of the intracellular machinery (e.g., MAP1B) involved in axonal elongation.

Suppression of radixin and moesin alters growth cone morphology, motility, and process formation in primary cultured neurons

In this study we have examined the cellular functions of ERM proteins in developing neurons. The results obtained indicate that there is a high degree of spatial and temporal correlation between the expression and subcellular localization of radixin and moesin with the morphological development of neuritic growth cones. More importantly, we show that double suppression of radixin and moesin, but not of ezrin-radixin or ezrin-moesin, results in reduction of growth cone size, disappearance of radial striations, retraction of the growth cone lamellipodial veil, and disorganization of actin filaments that invade the central region of growth cones where they colocalize with microtubules. Neuritic tips from radixin-moesin suppressed neurons displayed high filopodial protrusive activity; however, its rate of advance is 8-10 times slower than the one of growth cones from control neurons. Radixin-moesin suppressed neurons have short neurites and failed to develop an axon-like neurite, a phenomenon that appears to be directly linked with the alterations in growth cone structure and motility. Taken collectively, our data suggest that by regulating key aspects of growth cone development and maintenance, radixin and moesin modulate neurite formation and the development of neuronal polarity.

High-density lipoprotein aggregated by oxidation induces degeneration of neuronal cells

We have previously reported that high-density lipoprotein (HDL) exhibits antineuritogenic effects on chicken cerebral cells in culture. In the present study, we show the effects of HDLs, oxidized by UV irradiation or heating, on chicken cerebral neurons in culture. Both treatments produced several physical and chemical changes in the HDLs, i.e., formation of lipid peroxides, enlargement of HDL diameters, an increased exposure of the tryptophan groups of the apolipoprotein A-I to a more hydrophilic environment, formation of bityrosines, and cross-linking of apolipoprotein A-I. When these treatments were performed in the absence of EDTA, most of the modifications described above were more intense and HDLs formed a macroaggregate that displays a rosette-like structure. The aggregated HDLs produced neurodegeneration and death when added to both undifferentiated and differentiated cerebral neurons in culture. This process was accompanied by the disorganization of the cellular microtubular cytoskeleton and hyperphosphorylation of the microtubule-associated protein tau. Native HDL or HDLs treated in the presence of EDTA inhibited the neuritogenesis of undifferentiated neurons but did not show any significant effect on the differentiated neurons in culture. The effects on the cellular cytoskeleton and morphology of aggregated HDLs recall those of the fibrillar beta-amyloid peptide. The present results suggest that aggregated HDLs could participate in neurodegeneration associated with oxidative stress in the CNS.

Suppression of KIF2 in PC12 cells alters the distribution of a growth cone nonsynaptic membrane receptor and inhibits neurite extension

In the present study, we present evidence about the cellular functions of KIF2, a kinesin-like superfamily member having a unique structure in that its motor domain is localized at the center of the molecule (Noda Y., Y. Sato-Yoshitake, S. Kondo, M. Nangaku, and N. Hirokawa. 1995. J. Cell Biol. 129:157-167.). Using subcellular fractionation techniques, isopicnic sucrose density centrifugation of microsomal fractions from developing rat cerebral cortex, and immunoisolation with KIF2 antibodies, we have now identified a type of nonsynaptic vesicle that associates with KIF2. This type of organelle lacks synaptic vesicle markers (synapsin, synaptophysin), amyloid precursor protein, GAP-43, or N-cadherin. On the other hand, it contains betagc, which is a novel variant of the beta subunit of the IGF-1 receptor, which is highly enriched in growth cone membranes. Both betagc and KIF2 are upregulated by NGF in PC12 cells and highly concentrated in growth cones of developing neurons. We have also analyzed the consequences of KIF2 suppression by antisense oligonucleotide treatment on nerve cell morphogenesis and the distribution of synaptic and nonsynaptic vesicle markers. KIF2 suppression results in a dramatic accumulation of betagc within the cell body and in its complete disappearance from growth cones; no alterations in the distribution of synapsin, synaptophysin, GAP-43, or amyloid percursor protein are detected in KIF2-suppressed neurons. Instead, all of them remained highly enriched at nerve terminals. KIF2 suppression also produces a dramatic inhibition of neurite outgrowth; this phenomenon occurs after betagc has disappeared from growth cones. Taken collectively, our results suggest an important role for KIF2 in neurite extension, a phenomenon that may be related with the anterograde transport of a type of nonsynaptic vesicle that contains as one of its components a growth cone membrane receptor for IGF-1, a growth factor implicated in nerve cell development.

Small bowel obstruction secondary to bezoar: CT diagnosis

Two cases of small bowel obstruction secondary to phytobezoar diagnosed by computed tomography (CT) and confirmed at surgery are presented. CT findings were dilated intestinal loops and an intraluminal mass with air bubbles retained in its interstices, resulting in a mottled appearance. We propose that definite diagnosis of small bowel bezoar can be made on the basis of these CT findings.

Duodenal schwannoma causing gastrointestinal bleeding: helical CT findings

Neurogenic tumors of the small intestine are extremely rare and represent an unusual cause of gastrointestinal hemorrhage. We present a case of schwannoma of the fourth portion of the duodenum demonstrated by helical computed tomography. Multiplanar reconstructions showed a hypervascular tumor arising from the inferior wall of the duodenum. The use of water as oral contrast agent instead of iodinated contrast permitted a better visualization of the intact mucosa and differentiated a hypervascular tumor from hypodense gastrointestinal content.

Expression and distribution of IGF-1 receptors containing a beta-subunit variant (betagc) in developing neurons

Betagc is a beta-subunit variant of the insulin-like growth factor-1 (IGF-1) receptor highly enriched in growth cone membranes prepared by subcellular fractionation of fetal rat brain (). The present study is focused on the expression and on the cellular and subcellular distribution of betagc in developing neurons and differentiating PC12 cells. In the developing cerebral cortex and, at least at early stages, in cultured primary neurons, betagc expression was found to be correlated with neurite outgrowth. In PC12 cells betagc expression was nerve growth factor (NGF)-dependent and also paralleled neurite outgrowth. In contrast, beta-subunits of the insulin receptor and/or of other IGF-1 receptors ("betaP5"; detected with antibody AbP5) were downregulated as betagc expression increased. Immunofluorescence studies confirmed the enrichment of betagc at growth cones and demonstrated morphologically its spatial separation from betaP5, which is confined to the perikaryon. At the growth cone, betagc colocalizes and associates in a proximal region with microtubules, but it seems independent of the more peripheral microfilaments. Some betagc immunoreactivity is detected in the perinuclear region of PC12 cells, most likely the Golgi complex and its vicinity. betagc seems to emerge from the periphery of this structure in an apparently vesicular compartment distinct from that carrying synaptophysin to the growth cones. The facts that (1) betagc expression is correlated closely with neurite outgrowth, that (2) it is regulated in PC12 cells by a neurotrophin, NGF, and that (3) betagc is concentrated in the proximal growth cone region raise new questions regarding a possible role of IGF-1 receptors containing betagc in the regulation of neurite growth.

CT evaluation of underlying cause in spontaneous subcapsular and perirenal hemorrhage

We evaluated the CT scans of 13 patients with spontaneous subcapsular or perinephric hemorrhage (SPH) associated with these underlying causes: 4 angiomyolipomas, 2 renal cell carcinomas, 1 renal metastatic malignant melanoma, 1 ruptured renal artery aneurysm, 1 adrenal myelolipoma, 1 ruptured renal abscess, 2 ruptured hemorrhagic cysts, and 1 patient with undiagnosed coagulation disorder. Our objective was to ascertain whether an underlying cause of SPH was identifiable by CT, and to determine the extension of the hematomas. Computed tomography identified the hematoma in all 13 cases (sensitivity 100 %). In all 12 cases in which there was a renal or adrenal anatomic lesion, the underlying cause was identified with CT (100 %), with correct diagnosis in 11 cases (91.6 %). The case in which no lesion was identified was the undiagnosed coagulation disorder. We conclude that CT is a useful technique for the initial evaluation of SPH, permitting diagnosis of hemorrhage and identification of the underlying cause.

Axonal origin and purity of growth cones isolated from fetal rat brain

The investigation of the molecular properties of nerve growth cones depends to a significant degree on their isolation from fetal brain in the form of 'growth cone particles' (GCPs). The availability of markers for developing axons and dendrites, as well as glial cells, has made it possible to characterize the GCP fraction in much greater detail than before and to optimize its yield. Marker analyses show that a member of the N-CAM family (5B4-CAM), synaptophysin, and especially GAP-43 and non-phosphorylated tau, are enriched in the GCP fraction. In contrast, MAP2 and, particularly, glial fibrillary acidic protein and vimentin are fractionated away from GCPs. Furthermore, GCP yield can be doubled relative to the original procedure, without compromising purity, by raising the sucrose concentration of the fractionation gradient's uppermost layer. The results indicate that GCPs are highly purified growth cone fragments with very little glial contamination, and that they are primarily of axonal origin.

Spontaneous aortocaval fistula: CT findings with pathologic correlation

We present a case of aortocaval fistula (ACF) secondary to spontaneous rupture of an atherosclerotic infrarenal aortic aneurysm into the inferior vena cava that was initially diagnosed with computed tomography (CT). This is believed to be the first report of this condition with CT demonstration of the exact site of fistula and CT-pathologic correlation. We retrospectively reviewed the CT findings of another two cases of ACF and the previous literature.

High-density lipoprotein inhibits UDP-N-acetylgalactosamine:GM3, N-acetylgalactosaminyltransferase and differentiation of cultured cerebral cells: comparison with a formerly described inhibitor of this enzyme

We have previously described a thermostable inhibitor of the UDP-N-acetylgalactosamine:GM3,N-acetylgalactosaminyltransferase (GM2 synthase) purified from chicken blood serum. Some properties of the GM2 synthase inhibitory preparation (IP) resemble those of high-density lipoprotein (HDL), i.e., both have a MW of 200,000 in native conditions and are resistant to denaturation by heat. These and other facts prompted us to test the possibility that lipoproteins regulate ganglioside biosynthesis in the CNS. For this purpose, serum lipoprotein fractions were isolated from chicken serum by flotation and were assayed as inhibitors of GM2 synthase activity and of neuron differentiation in culture. HDL (in contrast to fractions containing very low-density or low-density lipoprotein) inhibited GM2 synthase with the same specific activity as IP and inhibited neuron cell differentiation in culture in a similar way. Furthermore, these two preparations also share several other characteristics; i.e., both have the same cholesterol content, the same floating behavior on KBr gradients, and the same polypeptide pattern as detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and staining with Coomassie Blue, or after western blot and revealing with an antibody prepared against IP, which is able to diminish the inhibitory effect of this preparation. The results described indicate identity between HDL and IP and suggest that HDL (particularly apolipoprotein A) could play an important role on ganglioside biosynthesis modulation during CNS development. The antineuritogenic effect of HDL described in this study could be of physiological relevance during CNS development and response to injury.

Insulin-like growth factor I receptors of fetal brain are enriched in nerve growth cones and contain a beta-subunit variant

Nerve growth cones isolated from fetal rat brain are highly enriched in a 97-kDa glycoprotein, termed beta gc, that comigrates with the beta subunit of the IGF-I receptor upon two-dimensional PAGE and is disulfide-linked to this receptor's alpha subunit. Antibodies prepared to a conserved domain shared by the insulin and IGF-I receptor beta subunits (AbP2) or to beta gc were used to study receptor distribution further. Subcellular fractionation of the fetal brain segregated most AbP2 immunoreactivity away from growth cones, whereas most beta gc immunoreactivity copurified with growth cones. Experiments involving ligand-activated receptor autophosphorylation confirmed the concentration of IGF-I but not of insulin receptors in growth cone fractions. These results indicate the enrichment of IGF-I receptors in (presumably axonal) growth cones of the differentiating neuron. Furthermore, the segregation of beta gc from AbP2 immunoreactivity suggests that such neurons express an immunochemically distinct variant of the IGF-I receptor beta subunit at the growth cone.

A direct non-competitive idiometric enzyme immunoassay for serum oestradiol

We report a novel non-competitive enzyme immunoassay for oestradiol based on the use of two types of anti-idiotypic antibody that recognize different epitopes within the hypervariable region of the primary anti-oestradiol idiotypic antibody (Ab1). The first anti-idiotype, the betatype, competes with the analyte for an epitope of the primary antibody at the binding site. On the other hand, the second anti-idiotype, the alphatype, binds to the Ab1 in the presence of analyte but does not bind to the betatype/Ab1 complex because of steric hindrance. In the present format the biotinylated alphatype was captured onto anti-biotin IgG which was adsorbed on the surface of microtitre wells. Reaction mixtures containing the Ab1 complexed sequentially with an enzyme labelled second antibody reagent, with oestradiol standards or serum samples and with the betatype anti-idiotypic antibody were then allowed to react with the immobilized alphatype anti-idiotypic antibody. The enzyme activity of the bound fraction measured at 405 nm increased with increasing oestradiol concentrations over the range 0.06-2.5 ng/ml. The detection limit of the assay was 28 pg/ml. The intra-assay variation ranged from 3.5 to 12.4%, and inter-assay variation from 6 to 13.4%. The results obtained by the colorimetric idiometric immunoassay correlated well with those obtained by a direct radioimmunoassay (n = 85, r = 0.97). This non-competitive immunoassay, termed idiometric assay, for haptens permits the development of sensitive immunoassays with a wide working range, and a variety of end-point determinations depending on the label used (e.g., enzyme, chemiluminescent or fluorogenic compound).

Characterization of gp93, a novel, highly heterogeneous glycoprotein present in growth cone membranes

gp93 was first described in growth cones from fetal rat brain as a 90-97-kDa glycoprotein family that binds wheat-germ agglutinin and consists of at least 12 different isoelectric variants (pl range approximately 4.9-6.4). Of particular interest is that different sets of gp93 variants are expressed in growth cones isolated from different brain regions. The preparation of a polyclonal antibody to gp93 allowed further characterization of this glycoprotein. The carbohydrate groups of gp93 were partially characterized by digestion with different glycosidases. The results indicate that most or all oligosaccharide units are N-linked (asparagine-linked) and contain sialic acid. Two-dimensional polyacrylamide gel electrophoresis and western blot with anti-gp93 show that deglycosylated gp93 is an only slightly heterogeneous polypeptide of 66 kDa, indicating that gp93 heterogeneity is due, primarily or exclusively, to differential glycosylation. Analysis of the tissue distribution in fetal rat showed gp93 to be highly enriched in the brain. Immunoblots and immunostaining of cross sections of developing cerebellum revealed that gp93 is developmentally regulated in this tissue, associated primarily with growing parallel fibers and Purkinje dendrites. Immunostaining of neurons in culture shows significant amounts of gp93 in elongating neurites and growth cones. Our results indicate that gp93 is a developmentally regulated glycoprotein of the brain that is most prominent in growth cones and growing neurites and that appears to be glycosylated differentially by different neurons.

Juvenile rheumatoid arthritis of the knee: evaluation with US

PURPOSE

To evaluate the value of ultrasound (US) in assessing joint inflammation in patients with juvenile rheumatoid arthritis (JRA) of the knee.

MATERIALS AND METHODS

US scans obtained in 36 children (mean age, 8 years) with JRA of the knee were compared with those obtained in 30 healthy children.

RESULTS

Changes in synovial membrane (synovial thickness), presence of fluid in the suprapatellar bursa, and alterations in the contour (blurring) of the articular cartilage showed statistically significant differences between JRA patients and control subjects. US was more sensitive than physical examination for detecting a minimal amount of intra-articular fluid in 21% of JRA-affected knees with no clinical evidence of active disease.

CONCLUSION

US is a simple, rapid, inexpensive, and accurate method for assessing joint inflammation in patients with JRA of the knee.

Spontaneous duodenal fistula due to hepatic hydatid cyst

Communication of a hepatic hydatid cyst to the duodenum appears to be extremely rare. This is the first case described in the imaging literature of hepatic echinococcosis fistulized to the duodenum studied by computed tomography.

Variable membrane glycoproteins in different growth cone populations

The question of whether growth cones generated by different neurons contain distinctive membrane glycoproteins was examined. Growth cone particles (GCPs) were isolated from specific regions of fetal or early postnatal brain, and their membrane proteins were analyzed by 2D gel electrophoresis and Western blotting, using WGA as a probe. These blots were compared to those generated by synaptosomes from adult brain. The patterns reveal a number of WGA-binding glycoproteins that are uniformly present in these subcellular fractions and others that are found in GCPs from selected brain regions only. The results indicate, therefore, substantial pattern diversity for the different, restricted growth cone populations. Some of the WGA-binding glycoproteins seen in GCPs disappear with increasing age and are absent from synaptosomes, while others seem to become more prominent. One of the glycoprotein complexes present in all GCP and synaptosome fractions analyzed is gp93. It has an apparent molecular weight of 90-97 kDa and exhibits unusually high heterogeneity in GCPs from whole fetal brain. The gp93 complex covers a pI range from about 4.9 to about 6.4 and consists of at least 12 different species, probably isoelectric variants. In GCPs from different brain regions, the sets of gp93 species observed are different and characteristic. Neuraminidase digestion shifts the gp93 pattern to a more neutral pI but simplifies it only partially, indicating that variable sialic acid content explains the molecular diversity to some extent. Thus, gp93 is a glycoprotein complex whose members are expressed and/or posttranslationally processed differentially in different growth cone populations. Such a glycoprotein family may be involved in selective cell-cell recognition.

Internalization of the inhibitor of the N-acetylgalactosaminyltransferase by chicken embryonic retina cells: reversibility of the inhibitor effects

Retina cells from 6-day-old chicken embryos were cultured in the presence of an 125I-labeled protein inhibitor of the UDP-N-acetylgalactosamine:GM3,N-acetylgalactosaminyltransferase. The cells were labeled and did not lose the incorporated radioactivity when treated with 0.125% trypsin or 1 M NaCl at 37 degrees C for 1 hr, indicating that the iodinated inhibitor was inside the cells. Immunostaining procedures using an anti-inhibitor antibody were applied to the cells cultured in the presence of the inhibitor after permeabilization of the cells. The inhibitor was found inside the round cells virtually devoid of neurites, but not in flat glial-like cells or in process-bearing neural cells. Also found was an apparent self-recovery effect of the cells for both the anti-neuritogenic effect and the modification of the pattern of labeled gangliosides produced by the inhibitor when the agent was withdrawn from the culture medium after the initial period of 20 hr. This recovery was clearly observed 72 hr after the removal of the inhibitor.

Growth-regulated proteins and neuronal plasticity. A commentary

Growth-regulated proteins (GRPs) of the neuron are synthesized during outgrowth and regeneration at an increased rate and enriched in nerve growth cones. Therefore, they can be used to some degree as markers of neurite growth. However, these proteins are not unique to the growing neuron, and their properties are not known sufficiently to assign them a functional and/or causal role in the mechanisms of outgrowth. During synaptogenesis, GRPs decrease in abundance, and growth cone functions of motility and organelle assembly are being replaced by junctional contact and transmitter release. However, there is a stage during which growth cone and synaptic properties overlap to some degree. We propose that it is this overlap and its continuation that allow for synaptic plasticity in developing and adult nervous systems. We also propose a hypothesis involving (a) trophic factor(s) that might explain the regulation of synaptic sizes and collateral sprouting. Some GRPs, especially GAP43/B50/pp46/F1, are more prominent in adult brain regions of high plasticity, and they undergo change, such as phosphorylation, during long-term potentiation (LTP). Without precise functional knowledge of GRPs, it is impossible to use changes in such proteins to explain the plasticity mechanism. However, changes in these "growth markers" are likely to be an indication of sprouting activity, which would explain well the various phenomena associated with plasticity and learning in the adult. Thus, plasticity and memory may be viewed as a continuation of the developmental process into adulthood.

[Maternal perception of the quality of care given to their children during hospitalization]

In order to evaluate the perception of mothers on the care given to their hospitalized children, a survey was specially designed and carried out with 100 mothers on the day of their child's discharge. Hospital care was rated excellent or good by a 96%, regular or bad by 4% of surveyed mothers. Most (74%) mothers saw at least one member of the caring team acting affectionately with their children; only 2% complained that her child was reprimanded or punished. Lack of equipment or human resources and comfort facilities were frequently perceived by mothers but quality of care was generally considered to be satisfactory. This kind of studies is probably useful to improve community's health services.

An endogenous inhibitor of N-acetylgalactosaminyltransferase inhibits retina neuron differentiation in culture

An inhibitor of N-acetylgalactosamine:GM3, N-acetylgalactosaminyltransferase (EC 2.4.1.92) from chicken blood serum, was tested for its activity on embryonic chicken neural retina in culture. The inhibitor did not change the cellular protein content of the cultures but produced a significant reduction of the labeling of gangliosides. The ratio of labeling of GD3 to GD1a increased from about 0.1 to about 0.8 in the cells cultured without or with the inhibitor, respectively. A striking effect of the inhibitor was seen on the morphology of the neurons, those cultured in its presence being practically devoid of neurites. Glial flat cells were apparently not affected.

Interovarian relationship in the secretion of progesterone during the luteal phase of the capuchin monkey (Cebus apella)

In basal conditions, progesterone concentrations were similar in the ovarian veins of the ovary +CL (3211 +/- 526 ng/ml) and the ovary -CL (3165 +/- 554 ng/ml), but after blocking the blood flow between the ovary +CL and the uterus, the progesterone values in the vein draining the ovary -CL decreased to 1218 +/- 394 ng/ml (P less than 0.01). When [3H]progesterone was injected in the ovary +CL, the radioactivity appeared earlier and more concentrated in the vein draining the ovary -CL (30 sec, 0.53% of injected dose) than in the femoral vein (150 sec, 0.08% of injected dose). Removal of the ovary +CL was followed by a brief maintenance of peripheral progesterone within luteal-phase levels. The in-vitro progesterone production by a suspension of cells isolated from the corpus luteum was 47.5 +/- 12.8 ng/ml/2 h, whereas luteal-like cells isolated from the ovary -CL secreted 14.3 +/- 6.0 ng/ml/2 h (P less than 0.01) into the medium. We therefore suggest that the symmetrical and high secretion rate of progesterone by the ovaries of the capuchin monkey indicates a between-ovary communication system, and that the luteal-like tissue of the ovary -CL can produce relatively large amounts of progesterone.