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Biomedical subjects

R Gonzalez

Publications and source records attributed to R Gonzalez.

At least 145 records · Page 8Linked to original sources
PubMed1994

Increased affinity of histamine H1 binding to membranes of human myometrium at the end of pregnancy.

1. The characterization of H1 binding sites in membrane preparations of human myometrium obtained from pregnant and non-pregnant women was performed by using 3H-mepyramine as the radioactive ligand. 2. Saturation curve analysis revealed that 3H-mepyramine is bound to a single class of binding sites. Changes in the H1 site binding parameters were observed at the end of pregnancy, resulting in an increased affinity relative to non-pregnant tissue (Kd: 131.0 +/- 8.8 (non-pregnant) and 72.5 +/- 7.5 (pregnant) nM, n = 6, P < 0.01). 3. A reduction in receptor concentration at the end of pregnancy was also observed, [Bmax: 565.2 +/- 43.7 (non-pregnant) and 309.6 +/- 25.9 (pregnant) fmol/mg prot, n = 6, P < 0.01]. It is possible that this reduction in Bmax could be attributed to a dilution factor due to the increase in membraneous proteins that occurs during gestation.

Female↗
PubMed1994

Scavenging action of propolis extract against oxygen radicals.

The ethanolic extracts of two types of cuban propolis (R and P) showed a similar manner of scavenging action against different species of oxygen radicals which were generated by specific chemical reactions. Chemiluminescence produced by superoxide generated from the xanthine-xanthine oxidase reaction was 50% inhibited by approximately 5 micrograms/ml of propolis R and 9.5 micrograms/ml of propolis P and by catechin (0.15 micrograms/ml) and superoxide dismutase (72 ng/ml). Alkoxy radical scavenging effect was similar to that produced by 0.11 micrograms/ml of alpha-tocopherol: inhibition of chemiluminescence by 50% was caused by approximately 0.6 micrograms/ml of both propolis preparations. The results indicate that the antioxidative properties of both propolis could be attributed to their free radical scavenging activity against alkoxy radicals and to a lesser degree against superoxide.

Catechin↗
PubMed1994

Radiofrequency catheter ablation as a cure for idiopathic tachycardia of both left and right ventricular origin.

OBJECTIVES: The purpose of this study was 1) to investigate the efficacy and safety of radiofrequency energy catheter ablation as curative treatment for idiopathic tachycardia of both left and right ventricular origin, and 2) to compare the usefulness of different methods used to map the site of origin of idiopathic ventricular tachycardia. BACKGROUND: Percutaneous radiofrequency catheter ablation has been used with dramatic success in the treatment of patients with Wolff-Parkinson-White syndrome, atrioventricular node reentrant tachycardia and bundle branch reentrant tachycardia. Limited data are available on the use of radiofrequency energy catheter ablation as curative treatment for idiopathic tachycardia of both left and right ventricular origin. METHODS: Twenty-eight consecutive patients (13 to 71 years old) presenting with idiopathic ventricular tachycardia were enrolled in the study. The site of origin of both left and right ventricular tachycardia was mapped using earliest endocardial activation times during tachycardia and by pace mapping. These mapping techniques were compared. RESULTS: Radiofrequency ablation was successful in all eight patients (100%) with left ventricular tachycardia. Tachycardia recurred in one patient. The ablation procedure was complicated by mild aortic insufficiency in one patient. Right ventricular outflow tract tachycardia was successfully ablated in 17 (85%) of 20 patients. The success rate at follow-up was 85%. In one patient, the ablation procedure was complicated by acute ventricular perforation and death. Pace maps from successful ablation sites were better than pace maps from unsuccessful sites (p < 0.004). Endocardial activation times at successful ablation sites were not different from unsuccessful sites (p < 0.13). CONCLUSIONS: Radiofrequency catheter ablation is an effective treatment for idiopathic ventricular tachycardia. The site of origin of tachycardia is best identified using pace mapping. Significant complications can occur and should be considered in the risk/benefit analysis for each patient.

Adolescent↗
PubMed1994

Topographic differences in amniotic fluid concentrations of prostanoids in women in spontaneous labor at term.

These studies were designated to determine if there are differences in prostanoid concentrations between amniotic fluid (AF) retrieved transvaginally from the membrane forebag (lower or forebag compartment) and fluid retrieved by transabdominal amniocentesis from the 'upper compartment' in women in labor. Fluid was retrieved from 53 women in active labor who underwent transabdominal and transvaginal amniocentesis. Fluid was assayed for prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha), 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM), thromboxane B2 (TXB2), and 6-keto-prostaglandin F1 alpha (6-k-PGF1 alpha) using sensitive and specific radioimmunoassays. Concentrations of all prostanoids measured were significantly higher in fluid retrieved by transvaginal than transabdominal amniocentesis; the magnitude of the increase (measured as the ratio of concentrations in the lower/upper compartment) was higher for PGF2 alpha and TXB2 than for the other prostanoids measured; for each prostanoid measured, there was a significant correlation between the concentration in the upper and lower compartment.

Amniocentesis↗
PubMed1994

Renal rupture after the Credé maneuver.

We report a case of renal rupture with development of a large perinephric urinoma and deterioration of renal function after the Credé maneuver in a girl with neurogenic bladder and detrusor sphincter dyssynergia without vesicoureteral reflux. After percutaneous drainage of the urinoma, management was changed to clean intermittent catheterization, and renal function returned to normal. We recommend that the Credé maneuver not be used in children with neurogenic bladder and nondenervated urethral sphincter.

Cysts↗
PubMed1994

Renal transplantation into the dysfunctional bladder: the role of adjunctive bladder reconstruction.

A retrospective review of pediatric renal transplantation at 3 centers identified 9 patients who had undergone major bladder reconstruction. Seven patients underwent bladder augmentation (5 gastric, 1 colonic, 1 ureteral) and 2 received gastric neobladders. Six patients required Mitrofanoff neourethras. Patient survival was 100% with initial graft survival of 56% during a mean followup of 29.4 months. Eight patients (89%) are presently dialysis-free with functioning allografts and all 9 (100%) are continent of urine. We conclude that renal transplantation and reconstruction to ensure continence are justifiable in even the most anatomically compromised children with end stage renal disease. It is essential that the pediatric urologist should have an integral role in the management of such cases.

Adult↗
PubMed1994

Scrotal ultrasound for evaluation of subacute testicular torsion: sonographic findings and adverse clinical implications.

There is an increased use of scrotal ultrasound in the clinician's office and emergency room for the investigation of scrotal pain. The use of real-time scrotal ultrasound for the diagnosis of testicular torsion has been described in the literature. A false-negative ultrasound examination can postpone the diagnosis of torsion and result in testicular loss. We examined 6 patients 1 day to 18 years old who had subacute testicular torsion with scrotal symptomatology (pain and/or swelling) for longer than 8 hours (range 12 hours to 6 days). Scrotal ultrasound was performed as 1 of the initial tests. A common sonographic pattern was an inhomogeneous testicle with hypoechoic areas alternating with hyperechoic areas and thickening of adjacent scrotal tissue. Another common finding was an edematous hyperechoic epididymis and a small hydrocele. In 4 of the 6 cases these nonspecific findings suggested a misleading diagnosis of tumor or epididymitis and resulted in delay of surgery and testicular loss. Treatment was not delayed in only 2 patients in whom the diagnosis of torsion was made initially by history and physical examination, and ultrasound was done for interest only. Misdiagnosis of intratesticular blood flow and some potential pitfalls of scrotal imaging by color Doppler ultrasound are discussed. We conclude that real-time scrotal sonography can be misleading in cases of subacute testicular torsion and, therefore, it should not be used in this clinical setting.

Acute Disease↗
PubMed1994

Distal hypospadias repair without stents: is it better?

We previously reported the results of the meatal based flap urethroplasty (Mathieu) for distal hypospadias repair. Of 49 patients in whom stents were left indwelling for 2 to 5 days meatal stenosis developed in 1 and there were no fistulas. In view of these good results and to decrease postoperative discomfort from bladder spasms, we performed 37 consecutive meatal based flap repairs without stents. Seven patients (19%) had urinary retention requiring catheterization several hours after surgery, of whom 3 had had a caudal block and 4 a penile block with 0.25% bupivacaine for postoperative pain control. In 5 patients (14%) a urethrocutaneous fistula developed, which required surgical repair. Of the patients with a fistula 2 were also among those who presented with urinary retention and 1 had concomitant meatal stenosis. One child had meatal stenosis only, requiring a meatoplasty after failed dilations. Subsequently, of another 16 children who underwent the Mathieu repair with stents a urethrocutaneous fistula and meatal stenosis developed in 1 (6.2%) and 15 patients had no complications. Overall of 65 patients in whom a stent was used 3 (4.6%) had complications, in contrast with a complication rate of 18.9% in the unstented group, representing a statistically significant difference (p < 0.05). The stent obviates urinary retention, which was unrelated to the type of anesthetic block used, and minimizes the incidence of fistula and stenosis. We conclude that the use of a multiperforated silicone urethral stent is advantageous for the outcome of this operation.

Adolescent↗
PubMed1994

Intraureteral metallic self-expanding endoprosthesis (Wallstent) in the treatment of difficult ureteral strictures.

Intractable and recurrent ureteral stricture presents a continuous challenge to the urologist. We report on 5 patients with severe ureteral stricture who were successfully treated with self-expanding metallic stents. Ureteral stricture occurred at ureteroileal anastomotic sites after neoplasm resection in 2 cases, multiple upper ureteral strictures were related to multiple surgical procedures for correction of bladder exstrophy in 1 and a ureteral kink developed in 1. Treatment with transluminal balloon dilation provided poor results but self-expanding metallic stents were used successfully with no major complications. In the last patient the stent and the overlying ureter were removed due to recurrent reflux; the gross and histological ureteral changes are discussed in detail. The technical approach is described, alternative therapeutic options are considered and pertinent literature is reviewed.

Adult↗
PubMed1994

Seromuscular colocystoplasty lined with urothelium: experimental study.

OBJECTIVES: Enterocystoplasty without bowel mucosa would be useful to prevent most complications related to the presence of bowel in the urinary tract. However, past attempts to remove the mucosa from intestinal segments have resulted in fibrosis and contraction of the patch. We designed this study to test the hypothesis that such contraction can be prevented by combining the principle of detrusorectomy and seromuscular colocystoplasty, covering the denuded urothelium with a de-epithelialized colonic segment, a procedure we named seromuscular colocystoplasty lined with urothelium (SCLU). METHODS: SCLU was performed in 14 female mongrel dogs weighing 20 to 25 kg. We performed the procedure with and without preservation of the intestinal submucosa and in animals with intact and previously reduced bladders. We describe a new animal model of reduced bladder capacity. Bladder capacity and histology were evaluated 1 to 6 months after the procedure. RESULTS: Twelve bladder specimens were available for analysis. In all cases, the seromuscular patches remained viable and well vascularized. When the intestinal submucosa was not preserved in the patch, there was moderate contraction of the patch with subepithelial fibrosis and the bladder capacity was not preserved. In contrast, when the submucosa was preserved, there was no fibrosis and the capacity was preserved. In animals with previously reduced bladder capacity by either subtotal cystectomy or talc-induced fibrosis, SCLU effectively augmented bladder capacity. CONCLUSIONS: The results suggest that the contraction of the intestinal patch in seromuscular enterocystoplasty can be avoided by the preservation of both the bladder urothelium and lamina propria, together with the submucosa and muscularis mucosa of the intestinal patch.

Animals↗
PubMed1994

THE RELATIONSHIP BETWEEN OXYGEN UPTAKE AND ION LOSS IN FISH FROM DIVERSE HABITATS

A recent examination of the relationship between O2 uptake (M(dot)O2) and diffusive sodium loss (JNaout) in a freshwater fish showed that Na+ losses after exhaustive exercise exceeded those expected on the basis of M(dot)O2, probably due to distortion of the paracellular tight junctions (the primary site of diffusive ion loss) and/or glomerular-type filtration caused by increased lamellar pressure. In the present study, an examination of this relationship in nine species of fish from diverse habitats supports this model. Under routine conditions, the rate of Na+ loss per unit of O2 consumed (termed the ion/gas ratio or IGR) was similar in all the species tested, averaging 61.6 pmol Na+ nmol-1 O2. After exhaustive exercise, the degree to which the IGR of each species increased relative to its routine levels (post-exercise IGR/routine IGR) was exponentially related to the relative rise in M(dot)O2, i.e. greater rates of O2 uptake led to even greater ion losses. Further analysis revealed that, although naturally active species had the lowest proportionate increase in M(dot)O2, by virtue of their high routine rates, they had the highest post-exercise rates of O2 uptake. In fact, there was an inverse correlation between post-exercise IGR and M(dot)O2, i.e. species with low M(dot)O2 values lost more Na+ per mole of O2 taken up than did species with high ones. Thus, naturally active species, such as the common and golden shiner, were able to achieve higher rates of O2 uptake while avoiding high rates of ion loss. Surprisingly, species such as banded sunfish, yellow perch and smallmouth bass did not limit ion loss associated with exercise despite their apparent ability to do so. They demonstrated a strong ability to limit ion losses caused by a brief osmotic shock and by exposure to soft water (both of which distort tight junctions).

Journal Article↗
PubMed1994

Physiological studies on gentamicin: phosphate repression of antibiotic formation.

The effect of inorganic phosphate on the fermentative production of gentamicin by Micromonospora purpurea has been studied using a chemically defined medium. Phosphate concentrations higher than 5.75 mM (1 g/liter-1) did not inhibit growth but specifically prevented antibiotic formation. Changes in the pH medium and carbon or nitrogen depletion were excluded as the cause of antibiotic underproduction. The use of a phosphate analogue, a protein synthesis inhibitor and the profiles of differential rate of antibiotic production suggested that phosphate itself transiently repressed gentamicin formation. Phosphate affected the formation of 2-deoxystreptamine from 2-deoxyinosose, a none phosphorylated substrate.

Arsenates↗
PubMed1994

Enumeration of selected leukocytes in the small intestine of BALB/c mice infected with Cryptosporidium parvum.

Neonatal, suckling BALB/c mice inoculated with Cryptosporidium parvum produce an infection characterized by continuous shedding of oocysts that spontaneously clears by the time the animals are three weeks of age. Neonatal mice were used to characterize the leukocyte subgroups present in Peyer's patches from the ileum and jejunum of Cryptosporidium-infected and healthy mice. After infection, ileal Peyer's patches showed a predominant CD8+ response, with abundant monocytes-macrophages (MOMA-2+) and nonlymphoid dendritic cells (NLDC-145+ cells). In contrast, jejunal Peyer's patches showed more T lymphocytes than ileal patches, with a predominance of CD4+ cells and many dendritic NLDC-145+ cells and MOMA-2+ cells. The present results showed that ileal and jejunal Peyer's patches are functionally different in response to Cryptosporidium parasites. These findings suggest a preferential involvement of jejunal Peyer's patches in T cell-dependent immunity against the parasite, whereas ileal patches may be associated with B cell expansion and maturation.

Animals↗
PubMed1993

A phase II study of dacarbazine and cisplatin in combination with outpatient administered interleukin-2 in metastatic malignant melanoma.

BACKGROUND: Based on prior experience with dacarbazine (DTIC) and an outpatient interleukin-2 (IL-2) regimen, the current study was conducted to improve the antitumor efficacy and assess the immunologic interactions between chemotherapy and IL-2. METHODS: Thirty-two patients were registered onto a treatment program, which included DTIC 750 mg/m2 with cisplatin 100 mg/m2, each by intravenous bolus on day 1. Recombinant IL-2 was administered on an outpatient basis intravenously by 15-30-minute infusion (24.0 x 10(6) IU/m2) daily on days 12-16 and 19-23 of a 28-day cycle for three cycles and then every 42 days for responding patients. RESULTS: There were responses in 13 of the 32 registered patients (41% response rate), including five complete and eight partial remissions. Responses in the liver, lung, spleen, lymph nodes, and soft tissue sites were noted. The median duration of response was 8.0 months (range, 3.0-20.0+ months), and the overall median survival duration was 10.2 months. Three patients (9%) are alive, free of disease, without any treatment at 32.0+, 36.0+, and 42.0+ months after initiation of treatment. Only minor nephrotoxicity was observed, and treatment delays were rare. CONCLUSIONS: Additional chemotherapeutic, hormonal, or biologic agents may be added to enhance efficacy further if they have toxicities that do not overlap.

Adolescent↗