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Biomedical subjects

H John

Publications and source records attributed to H John.

At least 55 records · Page 3Linked to original sources
PubMed1999

Urodynamic features of the gastric pouch after radical cystectomy and the relationship to oral intake.

PURPOSE: We studied the motility of orthotopic bladder substitution with stomach (gastric pouch) in adults with bladder cancer and the effect of oral intake as measured on urodynamics. We also investigated the probable relationship between continence and sensitivity of the proximal urethra. Anticholinergic medication effects on pouch motility were tested. MATERIALS AND METHODS: Six patients with a gastric pouch were questioned about quality of life 6 to 43 months after surgery, and examined urodynamically before and after oral intake. During the examination the proximal urethra (directly under the anastomosis between the pouch and urethra) was electrically stimulated to determine sensitivity. We tried to inhibit the peristaltic contractions with 20 mg. butylscopolamine intravenously. RESULTS: The main difference before and after oral intake was the onset time of peristaltic contractions. After eating the contractions began at a lower filling volume, which was statistically significant. There were no or insignificant differences in capacity and urodynamic parameters. We were successful in inhibiting the peristaltic contractions with anticholinergic medication. CONCLUSIONS: The gastric pouch is a valuable bladder substitute with sufficient volume, antireflux characteristics, satisfactory continence rate and adequate voiding behavior. Oral intake causes motor activity of the gastric pouch at a lower fill volume than fasting during urodynamic investigation. Anticholinergic medication may be useful for inhibiting peristalsis in the gastric pouch.

Administration, Oral↗
PubMed1998

Thermodynamic and structural characterization of cis-trans isomerization of 12-(S)-hydroxy-(5Z, 8E, 10E)-heptadecatrienoic acid by high-performance liquid chromatography and gaschromatography-mass spectrometry.

It is shown that 12-(S)-hydroxy-(5Z, 8E, 10E)-heptadecatrienoic acid (5-cis-HHT)--a physiological metabolite of arachidonic acid--is acid-catalyzed converted into a less polar substance with its maximum UV-absorption at (1)max=232 nm and a molar absorptivity of about epsilon=26600 +/- 200 M(-1)cm(-1). Using a reversed-phase high-performance liquid chromatographic (HPLC) method this equilibrium reaction (K(c) = 1.78 +/- 0.05 at pH 1.10 and 298 K) could be thermodynamicly characterized as a pH dependent, exergonic and exothermic reaction according to kinetics of a first order reaction (at pH 1.10 and 298 K: delta(R)G(o) = -1.42 +/- 0.07 kJ mol(-1), delta(R)H(o) = -3.50 +/- 0.9 kJ mol(-1), delta(R)S(o) = 7.0 +/- 3.0 J mol(-1)*K, delta(R)H*f = 100.0 +/- 4.0 kJ mol(-1)). Kinetic data for several pH-values and temperatures are presented. These data and structural characterization by gaschromatography-mass spectrometry (GC/MS) lead to the conclusion that 5-cis-HHT is isomerized to 12-(S)-hydroxy-(5E, 8E, 10E)-heptadecatrienoic acid (5-trans-HHT).

Chromatography, High Pressure Liquid↗
PubMed1998

Development and review of radioimmunoassay of 12-S-hydroxyheptadecatrienoic acid.

For more than 25 years 12-S-hydroxyheptadecatrienoic acid (HHT) has been known to be a product of thromboxanesynthase (TX-Syn) when synthesized with thromboxane A2 (TXA2). Although there are some hints that HHT has anti-aggregatory effects, to date, it has neither been shown to have any specific pathological relevance nor is there much information about its physiological role. This review presents a summary of the physicochemical properties of HHT, its chemical synthesis, the impact of various biological systems on its enzymatic and non-enzymatic production and its physiological function and metabolization, as well as a survey of the most important methods for analyzing this unsaturated hydroxy-fatty acid. Due to the low antibody-raising potency expected in HHT, no immunological system for HHT quantification has been developed so far. In our report we present the development and validation of a sensitive and reliable, competitive radioimmunoassay (RIA) suitable for the quantitative determination of HHT. HHT was produced by an enhanced enzymatic method using platelet-rich plasma (PRP). With an effective and modified liquid-liquid and solid-phase extraction method we were able to produce highly purified HHT (97% purity by GC/MS) in sub-milligram ranges. These fractions were used for the synthesis of BSA-antigen-conjugates and for immunization of rabbits. The tritiated tracer was synthesized using prostaglandin H synthase for the production of prostaglandin H2 (PGH2) followed by an aqueous reaction with Fe(2+)-solution to rear-range PGH2 to HHT. The dynamic range of the assay was from 30-400 pg/tube, with a sensitivity of approximately 40 pg/tube. The evaluation of the assay was performed by a HPLC-RIA method as well as by correlation with a quantitative HPLC method and correlation with TXB2 concentrations in a blood coagulation study. The assay may be useful for the quantification of HHT in several tissues and body fluids under various physiological conditions and may also help to understand the possible physiological role of HHT in biological processes.

Animals↗
PubMed1998

A new operative method to treat high teat stenoses in dairy cows.

OBJECTIVE: To evaluate in a pilot study an alternative technique using theloscopic surgery in the management of proximal teat stenoses of dairy cows. MATERIALS AND METHODS: The study included three lactating dairy cows (mean age 3.5 years) with a stenotic fibrous lesion in the proximal region of a teat. The lesions were suspected to be of traumatic origin and the diagnoses were confirmed by ultrasonography. For surgery, the cows were sedated and the base of the teat anaesthetized. The resectoscope was introduced through an incision in the teat cistern. The surgical area was continuously irrigated with saline solution and the stenotic lesions electroresected. Haemorrhage was controlled whenever possible by electrocoagulation. RESULTS: In two cows, the procedure was successful and resulted in normal milk flow. One of the two cows was slaughtered soon after the operation for reasons unrelated to udder health. The other cow could be milked normally at a follow-up examination 4 months later and on ultrasonography, there was no recurrence of the stenotic lesions. In both cows, there was no evidence of concurrent intramammary infection. In the third cow, the procedure had to be discontinued because of severe intraoperative haemorrhage. CONCLUSIONS: Video-assisted theloscopic electroresection of fibrotic teats is a promising, novel and minimally invasive technique for the surgical correction of the glandular part of the cistern. It should be considered as an alternative to conventional surgical methods in valuable dairy cows.

Animals↗
PubMed1998

[Measuring nocturnal tumescence--value in diagnosis of impotence].

Nocturnal penile tumescence monitoring (NPT) is a non-invasive method to differentiate between organic and psychogenic impotence. The routine use of NPT monitoring in the evaluation of impotence is not effective due to its moderate sensitivity and specificity with small therapeutic benefit and relatively high costs. Patient's selection by intracavernous pharmacotest can improve the efficiency of the investigation, so the method can help to secure the diagnosis of a psychogenic impotence and then take effect on adequate therapy.

Diagnosis, Differential↗
PubMed1998

[Testosterone and impotence--when is androgen substitution advisable?].

Testosterone and dihydrotestosterone play a critical role during embryogenesis of the male genitalia. The development of secondary sex characteristics depends on normal circulating androgen levels. They maintain libido and sexual potency. Before testosterone supplementation men with erectile failure should receive through hormonal investigation. Testosterone is useless in the treatment of erectile problems in men with normal androgen levels. Testosterone can be administered by intramuscular, oral or transdermal routes. Transdermal systems produce serum testosterone levels closely mimicking the diurnal pattern described in healthy young men. In elderly men during long term therapy, prostate specific antigen should be measured regularly to anticipate malignant growth in the prostate.

Adult↗
PubMed1998

[Video-assisted theloscopic electroincision of a high teat stenosis].

Results of surgery of high teat stenosis remained disappointing until nowadays. The aim of this pilot study was to elaborate a new theloscopic surgical resection. A 5.5 year old swiss milk cow was suspected to have posttraumatic high teat stenosis. Diagnosed was ascertained by teat sonography. Animal was sedated and local anesthesia was performed at the base of the teat. After a teat side incision, resectoscope was introduced. Stenosis was electro-divided under continuity saline-solution irrigation and coagulation of bleeding vessels. After a follow-up period of 4 months, the cow was milked without residual. No intercurrent infections occurred. There were no signs of recurrence in the control teat sonography. Theloscopic electroresection of teat stenosis is a possible new, surgical, minimal invasive, option, to treat high teat stenosis.

Animals↗
PubMed1997

Reversed-phase high-performance liquid chromatographic method for the determination of the 11-hydroxythromboxane B2 anomers equilibrium.

An improved reversed-phase HPLC method for the separation and detection of both hemiacetalic 11-hydroxy anomers of thromboxane B2 (TXB2) is described. Water-acetonitrile mixtures have served as mobile phases. By diminishing stepwise the temperature of the chromatographic system from 40 to 0 degrees C, the UV-absorbance profile of TXB2 changed from one broad peak to two clearly separated narrow peaks corresponding to the two anomers existing in equilibrium. Modification of the mobile phase pH from 1.6 to 6.9 (0 degrees C) resulted in different concentration ratios of the anomers. The equilibrium constant and the Gibbs free energy were calculated. The intermediate open aldehyde form of TXB2 is unstable and, therefore, cannot be observed either by HPLC or by 1H NMR measurements.

Chromatography, High Pressure Liquid↗
PubMed1997

Prostaglandin- and thromboxane-producing activity of isolated luteal cells from pseudopregnant rabbits.

The pseudopregnant rabbit is proposed as a suitable model for studies on physiology and endocrinology of the luteal phase. Pseudopregnancy is defined by corpus luteum function from day 1 to day 12 post hCG, as demonstrated by peripheral progesterone concentrations. The corpus luteum is highly vascularized which is extremely important to ensure progesterone secretion. Prostaglandins are potent vasoactive compounds and may be involved in controlling the ovarian/luteal blood flow. The present studies were designed to investigate the capacity of luteal cells for their intracellular production rates of prostaglandins in the early luteal phase. Pseudopregnancy was induced with a subcutaneous injection of FSH/LH, followed two days later by an intravenous injection of hCG, on days 0, 1 to 4 of pseudopregnancy luteal cells were isolated and incubated for 4 days. Media were collected every 24 h and analyzed for prostaglandins. The luteal cells were characterized by immunocytochemistry and progesterone measurements. Cultured luteal cells were able to convert exogenously applied arachidonic acid into PGI2, PGE2, PGF2alpha, and TXA2. The major compound that could be detected in the culture medium and in the cells was PGI2. The absolute values of the production pattern varied in all experiments in the ranges PGI2 > PGE2 > PGF2alpha > TXA2 with the greatest difference on day 3. In view of this fact the corpus luteum may contribute locally synthesized prostaglandins to regulate its own function. The physiological meaning of these findings should now be studied in a more optimal environment such as organ culture.

Animals↗
PubMed1997

Indinavir urinary stones as origin of upper urinary tract obstruction.

The development of HIV protease inhibitors has dramatically improved the treatment prognosis of HIV-infected patients. The treatment, however, is associated with the potential for adverse events that are unique to protease inhibitors. One of them, Indinavir, can lead to the development of urinary stones. Three weeks after starting treatment with Indinavir, Zidovudine and Lamivudine, a 66-year-old patient developed symptomatic hydronephrosis on the right side due to multiple Indinavir stones blocking the ureter. Microhematuria and characteristic crystals were found in the urine. After interruption of treatment and increased fluid intake, the crystallurea was not longer detectable and the patient became asymptomatic within 3 days. Nephrostomy and ureteral stent placement were not necessary. Patients on treatment with Indinavir are required to maintain a fluid intake of at least 1.5-2 l/day to reduce the risk of crystallization and urinary stones. Pharmacologic metaphylaxis to prevent crystallization is not recommended.

Aged↗
PubMed1996

[Bronchus carcinoid tumor in the Tessin canton, retrospective analysis of 13 years and literature review].

Between 1981 and 1993, 27 bronchial carcinoids were diagnosed in patients living in the Swiss Canton of Ticino, with a mean age of 55 (24-78) years. The incidence was 0.79/100,000 inhabitants. Main symptoms were cough (41%), hemoptysis (30%) and bronchial obstruction such as pneumonia or atelectasis (26%). There were no cases with carcinoid crisis. Preoperative evaluation included chest X-ray (100%), bronchoscopic biopsy (84%), computed tomography (44%) and mediastinoscopy (15%). Some 69% of the patients underwent lobectomy and 15% segmental resection. Pneumonectomy was required for curative surgery in 2 patients. One patient underwent bronchoscopic resection. Surgery is generally indicated. The 5-year survival rate for typical carcinoid was 94% and was significantly reduced to 42% in atypical carcinoid cases (p = 0.02). Prognosis after radical surgery is favorable and depends mainly on lymph node involvement and the histological type of carcinoid.

Adult↗
PubMed1996

Intraurethral prostaglandin improves quality of vacuum erection therapy.

OBJECTIVE: The aim of this study was to investigate whether intraurethral prostaglandin E1 (PGE1) improves vacuum-induced penile rigidity. METHODS: Nineteen patients with a mean age of 55 years (range 30-66 years) complaining of erectile dysfunction for 24 months (range 3-156 months) were investigated. The penile diameter was measured and a mark was made 50 mm proximal of the coronary sulcus on the flaccid penis. Twenty micrograms of liquid PGE1 (pH 4.5; 308 mosm/l) were instilled intraurethrally; thereafter the meatus was occluded for 10 min. Penile diameter and increase in length of the initially 50-mm line were measured with both pure vacuum-induced erection as well as combined with PGE1. RESULTS: The vacuum erection device alone lengthened the distance by 26 mm (range 18-64 mm) and the diameter by 4 mm (range 2-10 mm). Combined with PGE1, 36 mm (range 27-70 mm; p = 0.016) and 7 mm (range 2-11 mm; p = 0.04) were found, respectively. CONCLUSION: We conclude that PGE1 significantly increases vacuum-induced tumescence. Optimized pharmacological preparations for intraurethral application are a new way to further improve vacuum-assisted erection.

Adult↗
PubMed1996

[Kaposi sarcoma of the glans penis with meatal obstruction. Case report and literature review].

Kaposi sarcoma was first described by Moritz Kaposi 1872. It is a disease of the reticuloendothelial system. Preferred manifestations are mainly skin, mucosa and gastrointestinal tract. Location of penile glans with meatal obstruction has been mentioned to date in 4 cases. We report a patient with acquired immune deficiency syndrome who presented a meatal obstruction caused by Kaposi-sarcoma. In this patient with a survival time of 8 months meatotomy and locoregional radiotherapy was an adequate therapy.

Acquired Immunodeficiency Syndrome↗