A spectroscopic study of the hydrogen bonding and pi-pi stacking interactions of harmane with quinoline

A spectroscopic (UV-vis, Fourier transform IR, steady state, and time-resolved fluorescence) study of the interactions of the ground and excited singlet states of harmane (1-methyl-9H-pyrido/3,4-b/indole) with quinoline has been carried out in cyclohexane, toluene, and buffered pH=8.7 aqueous solutions. To analyze how the number of rings in the substrate influences these interactions, pyridine and phenanthridine have also been included in this study. In cyclohexane and toluene 1:1 stoichiometric hydrogen-bonded complexes are formed in both the ground and the excited singlet states. As the number of rings of the benzopyridines and the solvent polarity increase hydrogen-bonding interactions weaken and pi-pi van der Waals interactions become apparent.

Membranous glomerulonephritis associated with hepatitis C virus infection in renal transplant patients

BACKGROUND

Hepatitis C virus (HCV) infection has been described in association with various types of glomerular diseases, usually type I membranoproliferative glomerulonephritis and rarely membranous glomerulonephritis (MGN). In this article, we describe the first series of MGN exhibited in renal transplant patients and associated with HCV infection.

METHODS

From January 1980 to December 1994, 2045 kidney transplantations were performed in our renal transplant units. A retrospective analysis demonstrated an overall 20% prevalence of HCV virus-positive patients; 409 transplanted patients were HCV positive (ELISA and RIBA).

RESULTS

Fifteen patients developed an allograft MGN (3.66%) 24 months after renal transplantation. MGN appeared in the form of significant proteinuria (>1.5 g/24 h) with stable renal function. In all cases, graft biopsy demonstrated a thickening of the capillary wall, subepithelial electron-dense deposits, and IgG and C3 diffuse granular deposits along the basal membrane. Ten cases were considered de novo, two cases were considered recurrent MGN, and three cases were considered undetermined because the primary renal disease was chronic glomerulonephritis. All patients showed negative antinuclear antibodies and cryoglobulins, normal complement, and negative rheumatoid factors. During follow-up (an average of 2 years), 12 patients developed a progressive worsening of renal function, with increased serum creatinine and persistent proteinuria; 8 of the 12 patients returned to dialysis. Of the remaining three cases, two patients showed partial remission of nephrotic syndrome after high doses of steroids, and one patient persisted with stable renal function and proteinuria (<2 g/24 h.).

CONCLUSIONS

In summary, HCV is preferentially associated with MGN in renal transplant patients, rather than with membranoproliferative glomerulonephritis as in the normal adult population. MGN associated with HCV infection has a similar clinical picture and outcome to posttransplant idiopathic de novo MGN, with persistent massive proteinuria and progressive deterioration of renal function.

Recurrent type III membranoproliferative glomerulonephritis after kidney transplantation

The first well-documented case of recurrent type III membranoproliferative glomerulonephritis after kidney transplantation is reported in this article. A 48-year-old man was admitted to the hospital because of nephrotic syndrome and moderate renal failure. The renal biopsy showed double-contour images at light microscopy. Electron microscopy revealed electron-dense deposits in the mesangium and in both the subepithelial and subendothelial sides of the basement membrane. Subepithelial deposits were sometimes hump-like and produced an irregular disruption of the lamina densa. A diagnosis of type III membranoproliferative glomerulonephritis was suggested. The patient had a rapid decrease in renal function and received dialysis in 3 months. Three years later, he received a cadaveric kidney transplant, and subsequently recovered normal renal function. Proteinuria appeared after 13 months, and a biopsy of the graft demonstrated recurrence of the original disease. Seven years after transplantation, he returned to hemodialysis.

Partition coefficients of indoles and betacarbolines

Partition coefficients for substituted indoles and betacarbolines were determined in octan-1-ol/water and cyclohexane/water. A comparative study of the results in both systems allows us to discuss the effects played by the different molecular structures, substituents, and aromaticity on the distribution properties of these compounds. In particular, the hydrogen-bond donor (HBD) and hydrogen-bond acceptor (HBA) properties of these solutes were characterized and compared with those of structurally related compounds. The Abraham solute descriptors were estimated and partition coefficients (log P) calculated and compared with the experimental values. The results show that the HBD properties are similar for indoles and betacarbolines, and the HBA capacity, as expected, is significantly enhanced by the contribution of the extra pyridinic or piperidinic ring in betacarbolines. The effects of the substituent groups are presented in relation to their contribution to the distribution properties of the compounds studied.

Development of methanogenic consortia in fluidized-bed batches using sepiolite of different particle size

The addition of support materials, such as sepiolite, to fluidized-bed anaerobic digesters enhances the methane production by increasing the colonization by syntrophic microbiota. However, the efficiency in the methanogenesis depends on the particle size of the support material, the highest level of methane production being obtained by the smaller particle size sepiolite. Because of the porosity and physico-chemical characteristics of these support materials, the anaerobic microbial consortia formed quickly (after one week of incubation). The predominant methanogenic bacteria present in the active granules, detected both by immunofluorescence using specific antibodies and by scanning electron microscopy, were acetoclastic methanogens, mainly Methanosarcina and Methanosaeta.

[Immunologic aspects related to hemoglobinopathic diseases]

The records of 96 patients with sickle cell disease were studied in relation to various immunological parameters. Age, sex, levels of total and fractionated serum protein and immunoglobulins, serum complements, antierythrocytic antibodies, circulating immune complexes, antiviral antibodies and lymphoid populations were taken into account. No major alterations in humoral immunity were found in this group of panamanian sickle cell patient.

The attentional system in brain injury survivors

The present study was designed to check the model of attention proposed by Posner and Petersen (1990), in patients with traumatic brain injury. We analyzed a series of neuropsychological tests administered to these patients after they were discharged from the hospital. Scores obtained from this group were subjected to factor analysis. The results of this analysis could be characterized by four factors which accounted for 85.4% of the variance. According to our data, factor 1 (perceptual and motor speed) and factor 2 (vigilance and alertness) represent Posner's posterior attention system. Factor 3 (encoding) and factor 4 (shifting) represent Posner's anterior attention system (AAS), but we have to consider that the AAS is not only attention but is shared by other cognitive processes. The results also suggest that the attention system could be stable and could be defined independently from the type of patient and type of illness.

Lichenoid drug eruption following the Blaschko lines

Eruptions similar to those of lichen planus (LP) are associated with systemic diseases or have been induced by many drugs. Linear lesions as a Koebner effect are frequently found in LP but isolated long, narrow, linear lesions, which may extend the whole length of the limb, are rare though rather more common in childhood. Some cases of zonal or zosteriform LP have been described in the literature. We describe a case of LP with a linear distribution following the Blaschko embryologic lines induced by nicergoline in a 65-year-old woman with a 6-month history of a pruritic eruption of erythematoviolaceous papules on the left breast, trunk and upper limb, with histological features of LP It would be the first case of linear LP associated with drugs.

Molecular associations of flavins with betacarbolines and related indoles

The interactions of a set of structurally selected betacarbolines (BC), (9H-pyrido[3,4-b]indoles) and indoles (IND) with two representative flavins (FN): riboflavin (RFN) and flavin mononucleotide (FMN) have been investigated by absorption and fluorescence spectroscopies. Spectral results provided evidence on the formation of 1:1 non-fluorescent molecular complexes, whose stability constants and other related thermodynamic parameters have been estimated from Stern-Volmer quenching analysis. The FMN complexes are somewhat more stable than the RFN complexes. The stabilities of the IND and BC complexes for a given FN follow approximately the order IND approximately tetrahydro BC < dehydro BC < fully aromatic BC. Protonation of the pyridinic nitrogen atom of BCs has a destabilizing effect, which is more pronounced for fully aromatic than for tetrahydro derivatives. The influence of structural factors on the stability of the complexes has been discussed and, aided by theoretical AM1 calculations, a qualitative model for the structure (stacking) and binding forces (cooperative localized charge transfer and dispersion forces) of the complexes has been proposed.

[Effect of cholelithiasis and cholecystectomy on duodenogastric biliary reflux]

The aim of this work was to study the influence of cholelithiasis and cholecystectomy on duodenogastric biliary reflux. Total bile acid concentration (TBAC) in fasting gastric juice was measured in 23 consecutive patients with cholelithiasis and functioning gallbladder before and at least 3 months after cholecystectomy (group 1) and in 14 healthy volunteers (group II). In group two, TBAC was 8.5 +/- 2.8 uMol/l (mean +/- sem), the preoperative value in group I was 32.8 +/- 8.9 uMol/l and the postoperative value 69.9 +/- 14 uMol/l (p < 0.002 compared with group II and < 0.035 compared with preoperative values). These results suggest that cholelithiasis, even with a functioning gallbladder is associated with a significant increase in bile reflux to the stomach, with raises further after cholecystectomy.