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Biomedical subjects

H Hamza

Publications and source records attributed to H Hamza.

At least 19 recordsLinked to original sources
PubMed2006

Demonstration of a nanoparticle-based optical diode.

We present the operation of an optical device that exhibits diodelike properties based on two adjacent layers of quantum dots (QDs) encased in a fiber-optic jacket. The possibility of a multilayered device is also discussed. A significant change in the emission spectrum of CdSe/ZnS core-shell QDs was observed when excited by the input laser and the fluorescence of other CdSe/ZnS core-shell QDs. The output of the diode can be taken to be either the incoming laser wavelength of light similar to a conventional diode, or the output may be considered to be one of the QD fluorescence wavelengths. Current work has applications in biological fluorescence monitors and sensors as well as in telecommunications applications.

Journal Article↗
PubMed2003

[Werner's syndrome and endocrine disorders].

Werner's syndrome is a rare autosomal recessive disease caused by the mutation of DNA helicase gene (WRN), characterized by the premature onset of multiple age-related disorders and skin changes similar to those observed in scleroderma. Some endocrinologic and metabolic disorders have been described in patients with Werner's syndrome. We report one case in a 41-year-old man issuing from consanguineous parents, who presented for exploration of hypoglycemic episodes and sexual impotence. Werner's syndrome was diagnosed on the basis of his characteristic clinical appearance. Metabolic disorders were insulin-requiring diabetes and hypertriglyceridemia. Endocrinologic investigation revealed nodular goiter, sub clinical primary hypothyroidism, hypergonadotrophic hypogonadism,adrenal cortical hypofunction and GH deficiency. Pathology examination of the skin biopsy showed a scleroderma-like aspect. Finally, osteoporosis, atherosclerosis and sub-capsular cataract were associated. Thus, in Werner's syndrome metabolic and endocrinologic investigation is necessary in order to treat these disorders and improve the patient's prognosis and life.

Adrenal Insufficiency↗
PubMed2002

Stability of the new antileukemic 4-pyranone derivative, BTMP, using HPLC and LC-MS analyses.

The stability of the new antileukemic kojic acid derivative, 5-benzyloxy-2-thiocyanatomethyl-4-pyranone (BTMP) was investigated. The degradation of BTMP was studied using specific and reproducible HPLC and LC-MS methods. Accelerated stability studies of BTMP were conducted in 0.1 M hydrochloric acid solution, physiological phosphate buffer solution (pH 7.5) and basic phosphate buffer solution (pH 9.0) at 30, 40 and 60 degrees C, respectively. The degradation of BTMP was found to follow pseudo-first order kinetics. In basic solution (pH 9.0) BTMP underwent rapid hydrolysis at a degradation rate constant (0.183-0.638 h-1) and degradation half-life (3.67-1.06 h) depending on the temperature setting. On the other hand, BTMP was significantly stable in 0.1 M hydrochloric acid solution (kdeg: 0.0017-0.0052 h-1; degradation half-life t1/2: 408.6-135.7 h), whereas in physiological phosphate buffer solution (pH 7.5), BTMP was only moderately stable (kdeg: 0.006-0.231 h-1; degradation half-life: 117.7-3.0 h). Arrhenius plots were constructed to predict the degradation kinetic parameters of BTMP at 25 degrees C and 4 degrees C. LC-MS analyses confirmed the degradation of BTMP in basic solutions and indicated at least two degradation products; namely 5-benzyloxypyran-2-ol-4-one (m/z 217.8) and 2-thiocyanatomethylpyran-5-ol-4-one (m/z 181.6).

Antineoplastic Agents↗
PubMed2001

Liquid chromatographic-mass spectrometric determination of celecoxib in plasma using single-ion monitoring and its use in clinical pharmacokinetics.

Celecoxib is a cyclooxygenase-2 specific inhibitor, that has been recently and intensively prescribed as an anti-inflammatory drug in rheumatic osteoarthritis. A robust, highly reliable and reproducible liquid chromatographic-mass spectrometric assay is developed for the determination of celecoxib in human plasma using sulindac as an internal standard. The run cycle-time is <4 min. The assay method involved extraction of the analytes from plasma samples at pH 5 with ethyl acetate and evaporation of the organic layer. The reconstituted solution of the residue was injected onto a Shim Pack GLC-CN, C18 column and chromatographed with a mobile phase comprised of acetonitrile-1% acetic acid solution (4:1) at a flow-rate of 1 ml/min. The mass spectrometer (LCQ Finnigan Mat) was programmed in the positive single-ion monitoring mode to permit the detection and quantitation of the molecular ions of celecoxib and sulindac at m/z 382 and 357, respectively. The peak area ratio of celecoxib/sulindac and concentration are linear (r2>0.994) over the concentration range 50-1000 ng/ml with a lowest detection limit of 20 ng/ml of celecoxib. Within- and between-day precision are within 1.58-4.0% relative standard deviation and the accuracy is 99.4-107.3% deviation of the nominal concentrations. The relative recoveries of celecoxib from human plasma ranged from 102.4 to 103.3% indicating the suitability of the method for the extraction of celecoxib and I.S. from plasma samples. The validated LC-MS method has been utilized to establish various pharmacokinetic parameters of celecoxib following a single oral dose administration of celecoxib capsules in two selected volunteers.

Celecoxib↗
PubMed2001

Synthesis, spectroscopic characterization, stability assessment and DNA-binding of new 2,6-piperidinedione derivatives.

This work reports on structural characterization of new antineoplaston (ANP) representatives, namely 3-(benzoylamino)-2,6-piperidinedione (BPD), 3-(4-methoxybenzoylamino)-2,6-piperidinedione (MPD) and 3-(p-nitrobenzoylamino)-2,6-piperidinedione (NPD). These compounds were prepared by reacting N-(4-substituted benzoyl)-glutamines with N-hydroxysuccinimide to afford the corresponding esters, which were heated to produce the corresponding 2,6-piperidinedione (PD) compounds. Non-destructive analytical procedures such as 1H NMR and NIR analyses confirmed the postulated chemical structures of these PD compounds. HPLC chromatograms at an ambient temperature or from solutions preheated at 30, 40 or 60 degrees C displayed only a single peak for each compound. Combination of heat with pH modification had virtually no effect on the obtained peaks, thus attesting to the stability and purity of these compounds. MS analysis displayed molecular mass ions indicative of BPD, MPD and NPD at m/z 233.4, 263.2 and 278.3, respectively. The fragmentation patterns using MS/MS analyses conformed to the structural and molecular formulae of the prepared compounds. Furthermore, preliminary biological assessments showed the capacity of these compounds to bind to the DNA. NPD, but not BMP or MPD, had a superior affinity to the DNA than the prototype ANP-A10.

Chromatography, High Pressure Liquid↗
PubMed2001

Determination of diclofenac sodium, flufenamic acid, indomethacin and ketoprofen by LC-APCI-MS.

A sensitive, selective and accurate high-performance liquid chromatography-mass spectrometry (LC-MS) assay for the determination of selected non-steroidal anti-inflammatory drugs (NSAIDs), namely diclofenac sodium (DIC), flufenamic acid (FLU), indomethacin (IND) and ketoprofen (KET), either individually or in mixtures, was developed. The examined drugs were injected onto Shim-pack GLC-CN column and were eluted with a mobile phase consisting of acetonitrile and 20 mM ammonium acetate solution (5:1 v/v)/pH 7.4 at a flow rate l ml min(-1). The mass spectrometer, operated in the single ion monitoring mode, was programmed to admit the negative ions [M-H] at m/z 295.9 (DIC), 280.1 (FLU), 355.8 (IND) and 252.9 (KET), respectively. The calibration curves were linear (r > or = 0.9993) over the concentration range 50-300 ng ml(-1) (FLU, DIC) and 100-500 ng ml(-1) (KET, IND) with detection limits of 0.5-4.0 ng. The mean predicted concentrations for the analytes were in the range -5.9 and 5.2% of the nominal concentrations. Within-day and between-day precision were in the range of 0.8-9.1% of the R.S.D. Mean recovery percentages of the individual compounds from laboratory-made mixtures and pharmaceutical formulations were (99.5-101.5%) and (100.6-102.2%), respectively.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Association of severe autosomal recessive osteopetrosis and Dandy-Walker syndrome with agenesis of the corpus callosum.

A severe form of autosomal recessive osteopetrosis associated with Dandy-Walker syndrome and agenesis of the corpus callosum is reported in a full-term boy born to consanguineous parents. The diagnosis was made shortly after birth. Clinical features were cranio-facial dysmorphy, macrocephaly, hepatosplenomegaly, severe anemia and thrombocytopenia. Skeletal radiographs revealed generalized increase in bone density and abnormal metaphyseal remodeling. Cranial ultrasonogram and computed tomography scan showed Dandy-Walker syndrome, agenesis of corpus callosum and hydrocephalus. The patient rapidly developed severe medullary deficiency and a severe pulmonary infection. He died at the age of 2 months. This association seems extremely rare and was not previously reported in the literature.

Abnormalities, Multiple↗
PubMed2000

Inosine and 2'-deoxyinosine and their synthetic analogues: lipophilicity in the relation to their retention in reversed-phase liquid chromatography and the stability characteristics.

The purines and among them inosine synthetic nucleoside derivatives and analogues belong to a group of compounds to which the attention is being paid because of their biological activities. Relationships of their various parameters are being investigated because of their effect on biological (antineoplastic, virostatic, immunosuppressive) properties. Hydrophobicity parameters expressed as the logarithm of the partition coefficient (log P) and the capacity factor k' for naturally occurring inosine, 2'-deoxyinosine, 2'-deoxyadenosine and 2'-deoxyguanosine and for inosine synthetic analogues 5'-deoxyinosine, 5'-chloro-5'-deoxyinosine and 2',3'-dideoxyinosine were measured. The effect of methanol percentage in the mobile phase and its pH on the retention of the studied compounds in a reversed-phase system was also examined. There was a good correlation between the lipophilicity expressed as log P and capacity factor k'. It was also determined that dissociation has a marginal effect on capacity factor k' in this group of nucleoside derivatives as the k' values were almost unchanged at various pH of the mobile phase used. The stability of the all investigated compounds was investigated in basic, neutral and acidic conditions. The values of the reaction constant k1 were calculated and effects of nucleoside structural characteristic on stability are discussed.

Chromatography, High Pressure Liquid↗
PubMed2000

Stability study of selected adenosine nucleosides using LC and LC/MS analyses.

The stability of the naturally occurring nucleoside, adenosine, and two synthetic chlorine-containing analogues, 2-chloroadenosine and 5'-chloro-5'-deoxyadenosine was studied using high performance liquid chromatography (LC) and liquid chromatography in combination with mass spectrometry (LC/MS). The stability of the examined nucleosides over pH range of 2-10 and at temperatures 40, 60 and 80 degrees C was measured using an LC method, whereas the products of hydrolysis were identified using LC/MS. The LC data indicated that the hydrolysis of the nucleosides followed pseudo-first order kinetics. The MS data proved that the fragment ions at m/z 136.3 and 170.3 referred to the hydrolytic products, adenine and 2-chloroadenine, respectively. The calculated values of the hydrolysis rate constant and half-life indicated that the presence of chlorine atom in the nucleoside base moiety increases apparently the stability of 2-chloroadenosine against acid hydrolysis compared to 5'-chloro-5'-deoxyadenosine and adenosine.

2-Chloroadenosine↗
PubMed2000

[Primary vesicoureteral reflux: report of 100 pediatric observations].

In this study, the authors have reported 100 cases of primary vesico-ureteral reflux (VUR) which occurred over a 7-year period. Patient age at presentation ranged from 1 month to 13 years, with a mean age of 3 years and 5 months. Overall, a higher rate of reflux was observed in the female population (63%) which was particularly evident after the age of 3 years, but with a male predominance during the first 12 months of life. In the majority of cases, the diagnosis of VUR was made following diagnosis and investigation of urinary infection (UI). A high level of UI was the most frequent sign of VUR (87% of cases), while in 6% of cases this disorder was diagnosed during the investigation of an uropathy which was found to be complex in all subjects. An analysis of 143 ureteral reflux units (URU) showed that VUR was pathological only in 17% of cases, and that the reflux grade was I, II, III and IV in 47.4, 28.14, 11.11 and 2.34% of cases respectively. DMSA scintigraphy in 38 patients showed signs of nephropathy in 24 cases, i.e., 14 scars and a decrease in kidney size in 9 cases, and an absence of fixation for one grade IV reflux. Forty subjects with 56 reflux units (34 grade I, II and 22 grade III, IV) were treated by antibiotic prophylaxis, with a positive outcome in 85% of cases in children under 2 years of age, compared to 40% for children aged over 2 years. Only 7 patients were treated by teflon endoscopic injection, and in one case a further injection was required; 21 patients with 30 reflux units were treated by surgery at a mean age of 4 years. In conclusion, VUR is a fairly common disorder, which is frequently detected via an IU; its potential gravity is associated with the risk of subsequent nephropathy.

Adolescent↗
PubMed1999

Fasting hyperglycaemia with oral glucose tolerance in acute Trypanosoma congolense infection of rats.

Intraperitoneal inoculation of rats with Trypanosoma congolense (Federe strain) produced a sustained parasitaemia from days 7 to 23 post-infection (pi). The fasting tail-blood glucose (FBG) concentrations in the infected animals increased (p<0.05) from 3.8+/-0.2 mmol/l on day 0 pi to 4.6+/-0.2, 4.9+/-0.2 and 5.8+/-0.3 mmol/l on days 7, 10 and 17 pi and decreased (p<0.05) to 3.1+/-0.8 and 2.9+/-0.7 mmol/l on days 20 and 23 pi, but the values in the uninfected controls varied between 3.8+/-0.3 mmol/l on day 0 pi and 3.9+/-0.2 mmol/l on day 23 pi. After oral glucose intake (1.0 g/kg) and determination of tail-blood glucose (BG) concentrations after 2 h, the percentage increase in BG from FBG was either comparable in infected and uninfected groups (days 7, 20, 23 pi) or lower (p<0.05) in the infected group (days 10, 17), suggesting the same rate of tissue glucose delivery in both groups or a faster rate in the infected group. Therefore, oral glucose tolerance in the infected rat was not impaired, but there was initial fasting hyperglycaemia followed by fasting hypoglycaemia in the later stage.

Animals↗
PubMed1999

Racecadotril versus placebo in the treatment of acute diarrhoea in adults.

METHODS: A two-centre, double-blind, parallel-group, randomized study was carried out to compare the efficacy and tolerability of racecadotril (100 mg three times daily) and placebo in 70 adult patients with acute diarrhoea. An objective criterion of antisecretory activity, stool weight, was used. RESULTS: Racecadotril produced a significant (P = 0.025) decrease in stool weight during the first day of treatment compared with placebo, and was also associated with significantly fewer diarrhoeic stools than placebo after 1 day of treatment (p = 0.027). Racecadotril and placebo were equally well tolerated, and the frequency of symptoms and signs was similar in both groups after 4 days of treatment. Fewer patients on racecadotril suffered from abdominal distension following treatment (5.6% vs. 18.2% on placebo). CONCLUSIONS: Racecadotril acts rapidly to resolve acute diarrhoea and has an incidence of adverse events similar to that of placebo.

Acute Disease↗
PubMed1994

[Brachyolmia at autosomal recessive transmission].

BACKGROUND: Brachyolmia is a form of spondylodysplasia; sufferers have a short stature limited to the trunk that is recessively inherited. There may be other minor abnormalities in some cases. CASE REPORTs. Four brothers, born to consanguineous normal parents, developed short stature and scoliosis that were only identified after the age of 5 years (from 8 to 14 years). The three oldest patients had facial anomalies with flattened mid-face and enlarged lips. X-rays showed scoliosis, universal platyspondyly, irregular iliac crests and short, enlarged femoral necks. CONCLUSION: Evidence of abnormalities in other areas than the spine confirms the heterogeneity for the disease.

Adolescent↗
PubMed1993

[Osteogenesis imperfecta with hypertrophic callus. Apropos of 2 cases with early onset].

BACKGROUND: The callus that forms at the site of recent fractures in patients with osteogenesis imperfecta is usually normal, but hyperplastic callus may develop. CASE REPORTS: Case 1. A hyperplastic callus with local inflammation developed at the site of a fracture of the left thigh of a boy, aged 11 months suffering from osteogenesis imperfecta. This disease was characterized by the progressive development of broad limbs, bone islands on skull x-rays and blue sclerae. He had also had fractures at the ages of 4 and 7 months. Follow-up showed that this boy, now aged 15 years, had several fractures with the development of similar hyperplastic calluses. These limitated joint motility, causing him to remain confined to his bed. Case 2. This girl of consanguineous parents had a fracture of the femora at the age of 1 month; she had blue sclerae and developed a hyperplastic callus. The roentgenographic studies showed generalized osteopenia and deformities indicating osteogenesis imperfecta. CONCLUSION: Hyperplastic callus may develop in osteogenesis imperfecta. Its diagnosis may be difficult with neoplasms of bone, such as osteosarcoma, and its treatment is difficult.

Bony Callus↗