PubMed Health⌕ Search

Biomedical subjects

M Melekos

Publications and source records attributed to M Melekos.

18 recordsLinked to original sources
PubMed2005

Efforts to create an artificial testis: culture systems of male germ cells under biochemical conditions resembling the seminiferous tubular biochemical environment.

Induction of meiotic and post-meiotic alterations of male germ cells in vitro has been the target of several research efforts since 1960. However, to date, the establishment of an ideal culture system in which spermatogonial stem cells can be maintained and directed to proliferate and undergo meiosis and complete spermiogenesis does not exist. This is attributed to the difficulties concerning the isolation and purification of defined subpopulations of germ cells and the establishment of male germ cell lines. In addition, there is no adequate knowledge regarding the optimal biochemical conditions that promote the survival and differentiation of germ cells in long-term cultures. This review focuses on the methodologies that have been proved sufficient to achieve differentiation of cultured male germ cells. Furthermore, the factors regulating spermatogenesis and the technical prerequisites to achieve differentiation of cultured male germ cells are described. Finally, the role of in vitro cultures of immature diploid germ cells in the therapeutic management of men negative for haploid cells in their testes and the subsequent potential genetic and epigenetic risks are discussed.

Animals↗
PubMed2004

Retrograde acucise endopyelotomy: is it worth its cost?

PURPOSE: To identify patients with ureteropelvic junction (UPJ) obstruction who will benefit from endoscopic Acucise incision of the stenosis and to compare the open Hynes-Anderson pyeloplasty with this minimally invasive technique. PATIENTS AND METHODS: In a prospective trial, 22 patients with primary and secondary UPJ obstruction were treated by Acucise endopyelotomy, and 18 patients were treated by Hynes-Anderson pyeloplasty. Preoperative and postoperative renal scans were used to determine the degree of obstruction and intravenous urography, ultrasound scanning, or both to assess the degree of dilation. RESULTS: There was a vast difference in the cure rate of the two groups: Hynes-Anderson pyeloplasty cured 94.5% of the patients, while in the Acucise group, the cure rate was only 32%. There was some improvement in another 22% of the patients, but the renal scan curve remained obstructed. The remaining 45% of patients failed to show any improvement. CONCLUSION: Acucise endopyelotomy will improve or cure only patients with good renal function and mild dilation of the pelvicaliceal system. Patients with severe dilation should be treated by Hynes-Anderson pyeloplasty.

Adolescent↗
PubMed1999

Changes of urodynamic findings after radical retropubic prostatectomy.

OBJECTIVES: We wanted to evaluate the urodynamic changes of radical retropubic prostatectomy in patients with localized prostate cancer and identify specific factors that could influence the postoperative continence status. METHODS: Sixty-six consecutive patients (mean age 68 years) were studied urodynamically within 1 week before surgery, and 44 of them at a mean 7.6 months after radical intervention. RESULTS: Complete urinary continence was achieved in 37/44 men (84. 1%) after 6 months and in 43/44 patients (97.7%) 1 year after surgery. Stress incontinence of varying degree improved with time. Seven patients demonstrated a moderate incontinence 4 months after radical prostatectomy and 1/7 was still incontinent after 1 year. Mean flow rate, maximum detrusor pressure, maximum urethral closure pressure (at rest and voluntary contraction of the sphincter) and functional urethral length showed significant changes after surgery. Detrusor instability, which was present in 31.8% of the 66 patients preoperatively, was not responsible for any case of postoperative incontinence. The urethral pressure profile was significantly reduced in all patients after surgery. CONCLUSIONS: The present study indicates that there are no preoperative alterations in bladder function such as detrusor instability to identify patients at risk for postoperative incontinence. Postoperative incontinence seems to depend upon sphincteric deficiency as expressed by the reduced pressures in the sphincteric mechanism.

Aged↗
PubMed1998

The inhibition of calcium oxalate monohydrate crystal growth by maleic acid copolymers.

The crystallization of calcium oxalate monohydrate (COM) was investigated at conditions of constant supersaturation both in the absence and in the presence of synthetic maleic acid copolymers at 37C, 0.15 M NaCl. The dependence of the rates of COM crystallization in the absence of inhibitors was found to be second order at low and first order at higher supersaturations suggesting a surface diffusion controlled mechanism. The presence of all copolymers tested at concentration levels up to 5 ppm retarded the rates of COM crystal growth up to 90%. The decrease of the COM crystal growth rates by the polymers depended on the nature of the comonomer polymerized with maleic acid and the order of inhibition was found to be vinyl acetate > N-vinylpyrrolidone > styrene. Taking into consideration kinetics data published in the literature concerning the inhibition of COM crystal growth, it is suggested that molecular weight also plays a role, with more inhibition at higher molecular weights. The morphology of the COM crystals grown was unaffected yet the crystals growing at lower rates in the presence of the copolymers were larger and their size more uniform. It is concluded that maleic acid copolymers are strong inhibitors of the crystallization of COM, the inhibitory activity being more pronounced in the case of the linear copolymers.

Adsorption↗
PubMed1996

A model system for the investigation of urinary stone formation.

OBJECTIVE: To develop an in vitro model system for the investigation of calcium oxalate urinary stones under conditions of spontaneous precipitation. MATERIALS AND METHODS: Using a calcium-ion selective electrode and automatic titrator, a test solution was kept supersaturated with calcium oxalate and the rate of crystallization measured. RESULTS: During the spontaneous precipitation at constant supersaturation at 37 degrees C, the induction times required for the precipitation of calcium oxalate monohydrate were inversely proportional to the supersaturation of the solution. No transient phases were identified and the interfacial energy determined from kinetic analysis was 28.4 mJ/m2. The rates of precipitation showed a first-order dependence on the degree of supersaturation and were in good agreement with those reported for the in vivo formation of calcium oxalate monohydrate stones. CONCLUSION: This experimental model system allows precise measurements of the kinetics of calcium oxalate monohydrate. From the dependence of the rates of precipitation on supersaturation, a mechanism controlled by surface diffusion is suggested.

Calcium Oxalate↗
PubMed1995

Prognostic factors for the operative correction of stress urinary incontinence.

Investigating the reliability of using some clinical and laboratory parameters as long-term prognostic factors in properly selected patients for stress urinary surgery could help in the prediction of the long-term result in each case. Toward this goal 51 women were examined prospectively, after they were assessed by clinical and laboratory exams with particular emphasis on urodynamic studies. Out of this group, 41 patients had genuine stress incontinence, and 10 had mixed stress incontinence. Twenty-seven women underwent Burch colposuspension while 24 had Stamey endoscopic bladder neck suspension. In all patients clinical and urodynamic evaluation was done with the same methodology before the operation, and after one month and six months, respectively. The study indicated that 73% of the incontinent women were cured. According to the "analysis of variance" and "correlation analysis" methods the factors which were found to influence the operative result were as follows: (1) Clinical factors including preoperative urgency, U.T.I. and previous gynaecological operations. These factors had negative prognostic value, while the grade of incontinence did not influence at all the outcome of surgery. (2) Urodynamic factors including preoperative residual urine, immediate operative first sensation of micturition, maximum urine flow rate, pre- and immediate postoperative bladder capacity and functional length. These factors influence the operative result negatively or positively according to the deviation from the normal values. Furthermore, the important immediate postoperative change of the urodynamic values was found to determine the result of the operation.

Female↗
PubMed1994

Evaluation of urodynamic parameters following Burch colposuspension.

Burch colposuspension is a very popular operation for the correction of genuine stress incontinence, due to its very good long-term results. The effect of the operation on the urodynamic parameters at the level of the bladder neck evaluated in this study, and correlated with clinical outcome. A total of 29 female patients with urinary stress incontinence who underwent a Burch colposuspension were clinically and urodynamically studied pre- and postoperatively. The urodynamic parameters chosen pre- and post-operatively were: maximum flow rate, residual urine, first sensation, bladder capacity, maximum detrusor pressure, detrusor pressure at maximum flow, functional urethral length and maximum closure pressure. Complete cure was obtained in 76% of the patients and improvement in 14%, the overall success rate being 90% for a mean follow-up of 18.4 months (range 8-27). Comparison of the pre- and postoperative urodynamic data revealed that the maximum urine flow rate, functional urethral length, maximum urethral closure pressure and residual urine were changed significantly after the operation. There were no statistical differences in the other parameters. All the urodynamic results that improved, however, only arrived at the lower limits of the values accepted as standard for normal individuals. This fact, however, did not prevent a good clinical result.

Female↗
PubMed1993

Myelolipoma of the adrenal gland.

We report 2 cases of large adrenal myelolipoma. Although their fatty nature was found by a CT scan and there was no endocrine activity, surgery was done because of their size and the caused discomfort.

Adrenal Gland Neoplasms↗
PubMed1992

Prostatectomy in the very aged.

The number of very aged men who demand prostatectomy for benign disease is increasing. We have assessed surgery results in 79 patients operated during the last four years. Sixty-two underwent endoscopic and 17 open procedure. Mortality rate was 3.7%. Two patients died in the first week and one patient three weeks after surgery. Morbidity rate was 61% but did not significantly affect the final operative outcome. Operative success rate six weeks postoperatively was 87%, satisfactory for this age group. After detailed preoperative evaluation and postoperative care by specialized age care team, prostatectomy is safe, effective and involves low-cost treatment.

Age Factors↗
PubMed1987

Rubinstein-Taybi syndrome.

Rubinstein-Taybi (broad thumb and big toe) syndrome, is characterized by mental and motor retardation and skeletal deformities of which broad thumb and large first toe are the most obvious. In addition, defects of the cardiovascular system and the urinary tract may be present. A case of Rubinstein-Taybi syndrome in a boy is presented.

Abnormalities, Multiple↗
PubMed1983

Idiopathic gangrene (Fournier) of the male external genitalia, with report of a case and review of the literature.

Fournier's gangrene, originally described by Fournier in 1883, is a rare and unusual ischaemic necrosis of the male external genitalia. Reports on the idiopathic penile and/or scrotal gangrene are relatively rare in newer publications. The aetiology of the disease which is characterized by a sudden onset, most commonly without prodromal symptoms, is still not fully understood. There is strong evidence, however, that Fournier's gangrene is a specific infection due to Streptococcus haemolyticus, group A, and/or anaerobic Streptococci. Presenting a case of our own, we take the opportunity to discuss the pathogenesis, pathomorphology, bacteriology and treatment of the disease.

Adult↗
PubMed1981

[Fever in urology].

Explore the source record for details and available documents.

Diagnosis, Differential↗
PubMed1981

[Priapism in childhood (author's transl)].

Priapism is a very rare problem in childhood. Although sickle cell disease and leukemia may produce persistent erection, juvenile priapism is most commonly idiopathic. The physiology and pathology of erection are reviewed, and the pathomechanisms of diseases which may produce priapism are described. If red cell sickling and leukemia are excluded, immediate surgical intervention by either corporosaphenous or corporospongiosum shunts is recommended for resolution of priapism and preservation of potency. A case of juvenile priapism is presented in which HCG medication as underlying factor is discussed.

Age Factors↗