The SPASIBA force field for chondroitin sulfate: vibrational analysis of D-glucuronic and N-acetyl-D-galactosamine 4-sulfate sodium salts

Normal-mode analyses were carried out on the two components of the chondroitin 4-sulfate linear glycosaminoglycan, a copolymer implying alternate D-glucuronate beta-(1-->3) and N-acetyl-D-galactosamine 4-sulfate beta-(1-->4) (hereafter named D-galactosamine 4-sulfate) residues. Scaled quantum mechanical calculations (SQM) using the density functional theory approach at different levels of theory (B3LYP/6-31G** and B3LYP/6-31++G**) were performed to obtain correct vibrational assignments. The SPASIBA empirical force field parameters were then obtained from both theoretical predictions and observed IR and Raman data. It is shown that calculations including diffuse functions at the B3LP/6-31++G** level and the introduction of the Na+ counterion are necessary to give correct assignments of the CO2- symmetric (nu(s)) and antisymmetric (nu(a)) stretching modes for the glucuronic carboxylate residue.

Study of spontaneous crystalluria on a series of patients in the Tadla Azilal Moroccan area

OBJECTIVES

There are few studies on crystalluria in the developing countries. The aim of the present study was carrying out a first study in Morocco on the frequency and the chemical nature of the crystalluria according to the sex and the age of human individuals living in the Tadla Azilal moroccan area.

METHOD

200 samples resulting from the morning urines of morning fasting individuals of the two sexes and different ages were collected. The pH was measured by a portable pH-meter "Pocket pH-meter ad 170 pH". The identification of the chemical nature of the crystalluria was carried out using a polarized light microscope "Olympus BX41". Such identification was based on morphology, polarization, and the pH of the urinary crystals.

RESULTS

In this series the positive frequency of crystalluria was 25.4% and was distributed on 3 age groups so that 27.9% in the youngest group, 32.6% in the middle aged group and 39.5% in the oldest one. The distribution on the sex is such as 53.4% in the man and 46.5% in the woman. A large majority (83.7%) of the crystalluria consists of homogeneous crystalluria. In the man, the Weddellite is dominant (69.6%) in the crystalluria while in the woman the Weddellite yields the place to the two phases of the uric acid (60%).

CONCLUSIONS

The studied series presents a non high frequency of crystalluria, which increases with the age. The factor sex has weakly increased the frequency of crystalluria in the man compared to the woman. The oxalocalcic nature is dominant in the crystalluria resulting from the man while it is the uric nature that is so in the woman. Other studies are necessary to be able to understand the etiology of a such difference, in the chemical nature of the crystalluria, between the two sexes.

Density functional theory and empirical derived force fields for the delocalized polaron form of polyaniline. Application to properties determination of an isolated oligomer using molecular dynamics simulations

Normal mode analyses obtained from quantum chemical calculations at the DFT level of theory have been performed for the repetitive unit of the delocalized bipolaron form of polyaniline (PANI). Empirical molecular mechanics force field parameters were consecutively refined using the SPASIBA software and applied to the molecular dynamics properties of an isolated dodeca oligomer model of the leucoemeraldine form of PANI. It is shown that effects of protonation of the emeraldine base spread over the four rings constituting the repeating unit. Molecular dynamics simulations reveal alternative bendings of the whole chain with a time period of 18-20 ps for the model of PANI under study.

[Analysis of calculi by infrared spectroscopy in children from the Moroccan mid-Atlas region]

Calculi from 45 Moroccan children aged between 2 and 15 years underwent morphological and infrared spectrometric analysis. The stones were three times more frequent in males than females (M/F = 3.09). Whewellite was the main component in 51.1% of cases and in 44.4% of stone nuclei, wheddellite in 8.9% of stones and nuclei, carbapatite in 6.7% of stones and 8.9% of nuclei, struvite in 15.6% of stones and 11.1% of nuclei. Ammonium hydrogen urate and uric acid were predominant respectively in 8.9% and 6.7% of stones and in 15.6% and 11.1% of nuclei. In addition to whewellite, struvite and ammonium hydrogen urate were the main components of bladder stones from both sexes. With respect to their calculi, whewellite was present in 84.4% of cases and wheddellite in 26.7%. Purines were present in 46% of calculi, especially as ammonium urate (28.9%) and uric acid (15.6%). Calcium phosphates as the main components were infrequent. In contrast, they were frequently identified in urinary calculi from children, respectively 64.4% and 40% for carbapatite and amorphous carbonated calcium phosphate.

[Analysis of urinary calculi in adults from the Moroccan Medium Atlas by Fourier transform infrared spectrophotometry]

OBJECTIVE

To determine the stone composition in adult patients from the medium Atlas of Morocco.

MATERIAL AND METHODS

A series of 183 calculi from adult patients (males: 123, females: 60) collected in medium Atlas of Morocco was analysed by Fourier Transform infrared spectroscopy. The stones were surgically removed (n = 168) or spontaneously passed (n = 15).

RESULTS

Kidney stones are encountered in 70.5% of calculi. The stones were twice frequent in males than in females (M/F = 2.10). Whewellite was the main component in 51.4% of the stones and 49.7% of the stone core, weddellite in only 7.1% of stones and 6.4% of the nuclei. Uric acid was predominant in 18% of stones and also 19.7% of nuclei, and carbapatite in 12.6% of stones and nuclei. All in all, whewellite was present in 77.6% of calculi and weddellite in 25.1%, carbapatite in 68.3% and PACC in 23.5%, struvite in 15.3%, uric acid in 20.8% and ammonium hydrogen urate in 14.2% of cases. Struvite stones were more frequent in females and uric acid calculi in males, in particular in patients aged more than 60 years old.

CONCLUSION

As observed in most countries, calcium oxalate was the most frequent major component of the stones (58.5%). Uric acid stones were more frequent (18%) than reported in Western countries, thus suggesting that particular dietary habits are involved in stone formation. The relatively high occurrence of struvite stones (8%) could be a marker of an insufficient early detection and treatment of chronic urinary tract infection.

[Correlations between crystalluria and composition of calculi]

The successful fragmentation of kidney stones by means of extracorporeal shock wave lithotripsy partly depends on stone composition. In case of incomplete or coarse fragmentation, multiple urological procedures following ESWL may be necessary for removal of obstructive fragments. It is difficult to be sure that a given stone will be successfully destroyed. X-ray examinations before treatment are useful to classify calculi as calcium stones or not. Nevertheless, such investigations are often not sufficient to identify the main crystalline phases which form the stone and that can make it either resistant or friable to ESWL.

OBJECTIVE

The aim of this study was to compare crystalluria and stone composition in patients with kidney calculi.

MATERIAL AND METHODS

Seventy-five untreated patients (54 males, 21 females) were included. Their first morning urine was collected three days before surgical removal of the stone. Urine samples were kept at 4 degrees C during 48 hours before examination.

RESULTS

Crystalluria occurred in 97.3% of urine specimens. Weddellite was the most frequent crystalline species found in urine (66.2%), followed by carbapatite (33.1%) and whewellite (23.1%). When compared to stone composition, crystalluria was mainly made of weddellite in urines from 68% of patients with weddellite-rich calculi. Stones from patients presenting with whewellite crystals in urine were mainly composed of whewellite in 88.9% of cases. Struvite stones were associated with struvite and carbapatite crystalluria in 85.7% of cases.

CONCLUSION

Crystalluria studies could be of clinical interest to predict the main crystalline phase of calcium-containing stones in order to define the best procedures for stone removal.

[Urolithiasis in children in West Algeria]

We analyzed a series of 61 stones from children aged 3 to 14 years old using Fourier transform infrared spectroscopy. The calculi were collected from urology departments of the University Hospitals of Oran, Sidi-Bel-Abbès and Mostaganem in West Algeria. This series is the first investigation concerning the composition of stones in children based on infrared analysis. Calculi were more frequent in males (75.4%) and mainly localized in the bladder (55.8%). Upper urinary tract calculi were more frequent in children over the age of 10 years, and the sex ratio was about 1. Calcium oxalate monohydrate was present in 70.5% of stones and was the main component in 50.8% of cases both in whole stones and nuclei. In contrast, calcium oxalate dihydrate was the main component in only 9.8% of calculi although it was present in 75.4% of stones. Ammonium urate was detected in 29.5% of stones and was always the main component of nuclei. Uric acid, observed in 31.1% of calculi, was the major constituent in 14.7% of stones and 19.7% of nuclei. Magnesium ammonium phosphate was observed in 24.6% of stones as a consequence of urinary tract infection by urea-splitting bacteria. Our observations emphasized that the anatomical location of stone and their composition were in accordance with those previously reported in other countries.