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Biomedical subjects

C Jimenez

Publications and source records attributed to C Jimenez.

At least 55 records · Page 3Linked to original sources
PubMed1997

Birth after combination of cryopreservation of sperm recovered from urine and intracytoplasmic sperm injection in a case of complete retrograde ejaculation.

OBJECTIVE: To assess whether sperm recovered from postejaculatory urine and cryopreserved can be used successfully for intracytoplasmic sperm injection (ICSI). DESIGN: Case report. SETTING: Laboratory of Developmental and Reproductive Biology, University Hospital. PATIENT(S): A couple with male infertility resulting from complete retrograde ejaculation. INTERVENTION(S): Freezing of sperm recovered from urine and subsequent use for ICSI. MAIN OUTCOME MEASURE(S): Survival, maintenance of fertilization, and pregnancy potential of sperm recovered from urine and cryopreserved. RESULT(S): On thawing, the sperm were still alive (32% viability) and very slightly motile (2% sluggish motility). Of 16 oocytes injected, 10 (62.5%) produced normal, cleaving embryos. A twin pregnancy with the birth of two healthy infant girls was achieved after the transfer of three embryos. CONCLUSION(S): The birth of normal, healthy female infants after ICSI with sperm recovered from postejaculatory urine and then cryopreserved demonstrates the usefulness of freezing such sperm even if motility is very low, to avoid surgery in the patient.

Adult↗
PubMed1997

Photosensitive polyurethanes applied to the development of CHEMFET and ENFET devices for biomedical sensing.

Chemical microsensors based on ion-selective field effect transistor (ISFET) transducers with ion-selective and enzymatic membranes have been fabricated. In this case, photolithographically patterned membranes based on acrylated urethanes have been developed and applied onto the gate area of ISFET chips. Aliphatic urethane diacrylate has been used for K+ and NH+4 membranes, while a photocurable hydrogel formulation based on other type of acrylated urethane has been optimized for urea-FET sensors. Resulting potassium and ammonium sensors show similar performances to those found when PVC membranes are employed. An integrated packaging process for ISFET-based sensors has been developed giving the possibility of carrying out most of the encapsulation on wafer level. For this purpose, a photocurable polyurethane encapsulant formulation has been optimized to be microstructured by photolithography. Finally, a preliminary study of biocompatibility of photosensitive formulations containing urethane oligomers has been performed in order to examine future applications in biomedical and clinical analysis.

Biosensing Techniques↗
PubMed1997

Plasma myosin and creatine kinase time-course after a concentric-eccentric field exercise.

The effect of a concentric (uphill run)-eccentric (downhill run) field exercise of 22.3 km long was examined in five healthy male volunteers to compare the time course of changes in plasma creatine kinase (CK) activity and beta myosin heavy chain (beta MHC) concentration observed during the recovery. CK and beta MHC were examined in blood sampled before exercise, immediately and 5 hours after exercise ceased. Screenings were conducted 1, 2, 3, 4, 5 and 7 days later. For every subject, the peak of plasma CK was transient and observed within the first 24 hours of recovery. In contrast to CK changes, plasma beta-MHC elevation was delayed and the peak, also transient, was observed the second or the third day after the exercise. The highly significant relationship between individual values of CK and beta MHC (P < 0.001) demonstrates that beta MHC could be used as a marker of skeletal muscle damage after acute exercise.

Adult↗
PubMed1997

[The examination of sperm in the study of male fertility].

The laboratory investigation of male fertility is based on semen examinations and allows assessment of all events occurring between the onset of spermatogenesis and ejaculation. The sperm count and semen cytology remain the first-line examinations, but can be completed by more specific examinations allowing assessment of spermatozoan functions involved in passage along the female genital tract and penetration of the oocyte. However, apart from azoospermia, there is no absolute criterion beyond which semen can be considered to be infertile. The results must be interpreted by taking into account all these examinations which can provide element concerning the aetiology of infertility, helping to guide subsequent treatment. When the use of various in vivo treatments has failed, patients may require medically-assisted procreation (MAP) techniques. The type of MAP chosen will depend on the characteristics of the semen and the functional capacities of the spermatozoa.

Ejaculation↗
PubMed1996

Peritoneal dialysis in liver disorders.

The purposes of this paper is to review the specific role of peritoneal dialysis (PD) in patients with liver disorders. We will pay attention to the confluence of liver diseases and situations for which chronic dialysis treatment is required. Hemodialysis (HD) and peritoneal membranes are safe barriers against the passage of the hepatitis C virus; consequently, while peritoneal effluent or HD ultrafiltrate drained from hepatitis B patients/carriers is infective, that from hepatitis C patients does not appear to present this risk. An important issue is horizontal transmission, which appears to occur with both viruses in HD units, and which is absent in peritoneal dialysis units. The incidence of hepatitis C among continuous ambulatory peritoneal dialysis (CAPD) patients is quite low, while it may reach almost 50%-60% of HD patients in some units. While hepatitis C transmission mechanisms are not completely understood and a vaccine is not available, PD provides some degree of protection when compared with HD, for and-stage renal disease patients. In summary, our experience and that of others, with a total of 19 PD-treated chronic liver disease patients, supports CAPD as the treatment of choice for cirrhotic patients with ascites who require chronic dialysis. Data on peritoneal diffusion of low molecular weight substances revealed a marked increase in most patients. The ultrafiltration capacity was clearly augmented with respect to noncirrhotic patients, making the use of hypertonic bags unnecessary. Hemodynamic tolerance was excellent. Complications and death were mainly related to liver disease complications. Spontaneous bacterial peritonitis (SBP), caused by gram-negative germs, is the most important complication directly related to ascites and may have some points in common with PD-related peritonitis. However, and in contrast to most PD peritonitis, two pathogenetic mechanisms have been suggested for SBP: (1) translocation of bacteria from the gut to the mesenteric lymph nodes, and (2) bacteremia in these patients is secondary to the general abnormal host defense mechanisms. Local factors such as intrahepatic shunting and the impairment of bactericidal activity in ascitic fluid favor the bacteria ascites. The hypothesis of a direct transmural contamination from bowel to ascitic fluid has been relegated to secondary bacterial peritonitis. Would cirrhotic patients with temporal or permanent renal function compromise benefit from peritoneal catheter placement and other PD practices to perform repetitive small ascitic drainages at home? Perhaps the time has arrived when hepatologists and PD nephrologists begin to work shoulder to shoulder in this particular field, as we have a common problem, the peritoneal cavity filled with fluid.

Ascitic Fluid↗
PubMed1996

Peritoneal functional changes induced by dialysate containing bicarbonate instead of lactate.

Lactate (L)-containing dialysate has a low pH, responsible for its poor biocompatibility. Dial-ysate-containing bicarbonate (B) with a physiological pH is available. We compare the peritoneal functional effects of these two solutions. Eight patients were studied two weeks apart using two consecutive peritoneal kinetic tests to determine convective and diffusive mass transfer coefficient (MTC) capacities for different solutes. Both L and B solutions were identical, except for pH and buffer content. Peritoneal equilibration values at four-hour dwell time were similar for all solutes, except for urea (B: 0.91 +/- 0.05 vs L: 0.87 +/- 0.06, p < 0.05). Peritoneal MTC (B vs L) values for urea (19.6 +/- 6.6 vs 18.2 +/- 4.5), creatinine (8.8 +/- 4.8 vs 7.8 +/- 3.5), phosphate (7.7 +/- 4.6 vs 6.0 +/- 2.2), and potassium (13.3 +/- 5.6 vs 11.7 +/- 5.0) were slightly higher for B (NS). Glucose-MTC was slightly lower for B (6.2 +/- 3.3 vs 7.5 +/- 3.2, NS). Ultrafiltration (UF) was lower for B (drained volume: 2120 +/- 204 vs 2443 +/- 285 mL after 4 hr, p < 0.05). Higher transperitoneal calcium [11 +/- 22 L vs -3.1 +/- 11.0 (positive balance) mg, p < 0.05] and sodium (48 +/- 30 L vs 13 +/- 20 mEq) removal were evident. With L, the loss of 43.0 +/- 6.3 mEq of bicarbonate appeared. The linear regression analysis of MTC values showed higher r coefficients for the bicarbonate solution. These results suggest that bicarbonate dial-ysate improves the diffusion capacity of the peritoneum with respect to lactate.

Adult↗
PubMed1996

Circulating burst-forming unit-erythroid (BFU-E) colonies as an early marker to measure the recombinant human erythropoietin response in peritoneal dialysis patients.

To evaluate circulating burst-forming unit-erythroid (BFU-E) cells after erythropoietin (EPO) treatment, 7 female continuous ambulatory peritoneal dialysis patients were studied [baseline hemoglobin (HB): 7-10.5 g/dL)]. EPO (4000 U subcutaneously) was administered twice weekly for two months. The control group consisted of 7 healthy women with similar demographic characteristics. Mononuclear cells (MC) (5 x 10(5)) were added to 1 mL of culture medium, supplemented with 30% fetal bovine serum, 2 U/mL of EPO, 1% bovine serum albumin, and 0.3% agar. To enumerate colonies derived from each circulating BFU-E, plates were examined by inverse light microscopy, identifying BFU-E as large aggregates with more than 100 hemoglobinized cells (HC). A remarkable individual response was observed, with Hb values ranging 8.4-13.6 g/dL at week 4 and 8.8-16.5 g/dL at week 8. Baseline levels of BFU-E in patients ranged 0-100/5 x 10(5) MC (0-358 mL of whole blood), and in controls they ranged 6-24/5 x 10(5) MC (29.6-101.3/mL) (NS). Hemoglobin levels after four and eight weeks of EPO showed a significant relationship with circulating BFU-E at baseline (r = -0.873, r = -0.928, respectively). The increment in Hb after eight weeks showed a significant relationship with baseline BFU-E (r = 0.812). Hemoglobin levels at the fourth to eighth week, and the increment in Hb after eight weeks, showed a significant, direct relationship with the increments in circulating BFU-E registered after one to two weeks of treatment. We conclude that, after the first week of EPO treatment, its effect on hemoglobin may be predieted by the increment in circulating BFU-E. Thus; a new tool to measure the earliest EPO effects has become available.

Adult↗
PubMed1995

Mitral annular calcification in CAPD patients with a low degree of hyperparathyroidism. An analysis of other possible risk factors.

Chronic renal failure has been suggested as a risk factor for mitral annular calcification (MAC), a degenerative process of the mitral annulus. The objective of the present study was to define MAC risk factors at the start of dialysis and 'de-novo' appearance after medium- or long-term CAPD, in a non-selected population (135 patients) with a low degree of secondary hyperparathyroidism. Echocardiographic studies were performed at the beginning of CAPD and every 1-1.5 years thereafter. Diagnosis of MAC was established by M mode and 2-D study. Seventeen of 135 patients studied at the start of dialysis showed MAC. Patients who showed MAC were older and presented a higher mean systolic blood pressure. The other anthropometric/demographic parameters did not show statistically significant differences. MAC thickness: mean 6.21 +/- 3.65 mm (range 3-17.2 mm). The posterior annulus was universally affected and in four patients the anterior annulus was involved. Seventeen of 76 patients included in the follow-up study developed MAC. No significant differences for demography, except age, with MAC patients being older, were found. Mean time on CAPD until de-novo MAC diagnosis was 49.7 +/- 26.9 months. MAC thickness: mean 4.97 +/- 1.6 mm (range 3-8.42 mm). The posterior annulus was affected in all patients except for one and in four patients the anterior annulus was involved. The most remarkable echocardiographic feature is the almost constant association of MAC with left atrial dilatation (LAD). The last one does not seem a consequence of mitral insufficiency, or systolic dysfunction. Left ventricular hypertrophy was universally found, with no different intensities for patients with or without MAC. In conclusion, a high incidence of mitral annular calcification has been found in CAPD patients. Our data do not confirm the role of classical invoked risk factors. Blood CaP product under 75, a moderate to mild degree of hyperparathyroidism and/or hypertension with left ventricular hypertrophy do not seem to be isolated risk factors during the CAPD period. Length of time on CAPD, for unknown reasons, seems to favour the appearance of MAC. At starting dialysis, high systolic blood pressure and left ventricular hypertrophy seem to be related to MAC. Diabetes appears to represent an additional risk factor. Further research on mitral annular calcification pathogenesis and its consequences is urgently required.

Calcinosis↗
PubMed1994

Effect of ingestion pattern on rehydration and exercise performance subsequent to passive dehydration.

Six male volunteers performed three tests, each comprising a passive heating session to obtain dehydration (loss of 2.6% body mass), followed by exercise on a treadmill until exhaustion (50% of maximal oxygen consumption) in a warm environment (dry bulb temperature 35 degrees C, relative humidity 20%-30%). In one test, the subjects exercised without rehydration (Dh). In the two other tests, 50% of the fluid lost in the dehydration session was replaced by drinking mineral water given either in one amount [913 (SEM 23) ml] before the exercise (Rh1) or divided into four equal portions [228 (SEM 5) ml] before the exercise and on three occasions at 15-min intervals during exercise (Rh4). Rehydration increased exercise duration in Rh1 compared to Dh [112 (SEM 7) min and 82 (SEM 3) min, respectively; P < 0.05]. The difference was not significant with Rh4 [103 (SEM 9) min]. A restoration of the time course of changes in plasma volume, plasma osmolality, heart rate and rectal temperature occurred immediately in Rh1 and as delayed in Rh4 until after 60 min of exercise. Our results demonstrated that the swift replacement of the fluid loss in the dehydrated subjects was beneficial to exercise performance by rapidly correcting the disturbances in body fluid balance.

Adult↗
PubMed1994

Treatment of autoimmune disease by immunomodulation through extracorporeal elimination and intravenous immunoglobulin.

If customary drug mediated immunosuppressive therapy leads to intolerable side effects or is inefficient, extracorporeal elimination and untargeted or targeted immunoglobin therapy modulating the immune response are taken into consideration for the treatment of patients with autoimmune diseases. Both elimination and immunoglobulin therapy, are not alternatives but appear to act complementary, if sequentially applied. Selective immunoadsorption is increasingly applied for extracorporeal elimination and is able to replace plasma exchange therapy. Both, hydrophobic interaction chromatography and affinity chromatography are effective in given clinical conditions. Therapeutic affinity chromatography appears to be superior to hydrophobic interaction chromatography, if an effective, rapid elimination of the disease promoting agent is desired. Experience with therapeutic chromatography collected in the past, indicates that a rapid elimination of immunoglobulins and the subsequent intravenous infusion of 7S immunoglobulin is superior to elimination or untargeted immunomodulation alone. These experimental approaches lead to an extension of the available treatment modalities. However, controlled trials rather than anecdotal reports are needed, to provide substantial information.

Adsorption↗
PubMed1994

Technical and clinical experience with protein A immunoadsorption columns.

Protein A adsorption (Immunosorba, Excorim, Sweden) is a potent tool for the rapid removal of antibodies from the circulation. In comparison to conventional plasma exchange therapy, Protein A adsorption offers the advantage of processing large amounts of plasma, removing up to 87% of the initial level of IgG in one session without a clinically significant loss of fibrinogen. So far 61 treatments have been carried out in our department without serious side effects.

Blood Component Removal↗
PubMed1994

Functional longevity of the human peritoneum: how long is continuous peritoneal dialysis possible? Results of a prospective medium long-term study.

Long-term peritoneal dialysis requires the maintenance of the transport function of the peritoneal membrane, and appropriate studies of possible changes are necessary. The quantification of peritoneal mass transfer coefficients (MTCs) has been judged to be the ideal method for the evaluation of peritoneal diffusion. The aim of the present study was to show the results of the prospective evaluations in long-term continuous ambulatory peritoneal dialysis patients. We have studied the clinical incidents and peritoneal function of 56 patients who started continuous ambulatory peritoneal dialysis between 1980 and 1988, and have completed at least 3 years of follow-up. Ultrafiltration capacity was calculated with a standardized formula. All patients were studied for peritoneal diffusion of urea and creatinine at least once a year. The evaluation consisted of a kinetic study done by means of a peritoneal equilibration curve for urea and creatinine, applying a bicompartmental mathematical model to calculate the MTCs. The sequential mean values for urea-MTC did not show significant changes over the observation period (20.7 +/- 5.9 mL/min for the first year v 19.8 +/- 6 mL/min for the fifth year). Creatinine-MTC values showed a significant increase over this period in the paired data analysis. The decrease of the urea-MTC to creatinine-MTC ratio may be an early and appropriate index for measuring these changes when the individual values are in the normal range. On the other hand, peritoneal ultrafiltration capacity significantly decreased over this period (1,800 +/- 530 mL/d v 1,400 +/- 600 mL/d, P < 0.01). The high rate of accumulated days of peritoneal inflammation was related to these significant changes, and thus may be proposed to be a good prognostic index of long-term peritoneal survival. These long-term functional changes might be related to the effect of injuries on the preservation of the normal peritoneal structure. We conclude that after 5 to 11 years, the human peritoneum shows functional stability (diffusion and water transport) in patients with low rates of peritoneal inflammation. With a few exceptions, represented by patients with a high rate of peritoneal inflammation, long-term peritoneal dialysis accomplished its newly entrusted task.

Adolescent↗
PubMed1994

Characterization of a monoclonal antibody to a human intra-acrosomal antigen that inhibits fertilization.

Among monoclonal antibodies (mAb) selected after the immunization of mice with human ejaculated spermatozoa, mAb I9G9 (IgG1 kappa) was found by immunoperoxidase staining to label most of the acrosome of human spermatozoa permeabilized with methanol-acetone. The antigen was poorly expressed on the surface of fresh ejaculated sperm, but was detectable on most viable sperm after 5-h incubation in medium containing human serum albumin (HSA) followed by 30-min incubation with the calcium ionophore A23187. This treatment resulted in acrosomal loss. Immunoelectron microscopy labeling with I9G9 mAb localized the antigen within the acrosome. Immunocytochemistry on testis sections showed that antigen was located in the round spermatids within the adluminal compartment of the seminiferous epithelium. Western blotting of sperm extract proteins showed that sperm intra-acrosomal (SIAA) recognized by I9G9 mAb had a polymorphism of immunogenic peptides from 16 to 35 kDa. Most of the antigenic peptides possessed an isoelectric point of approximately 5. When spermatozoa were treated with a series of protease inhibitors, the polymorphism of immunogenic peptides was reduced, suggesting that the multiple form of the antigen was due, at least in part, to proteolytic processing. In the testis, only a single peptide band of 35 kDa was detected with mAb I9G9. Studies of human tissue specificity by Western blotting showed that the epitope recognized by I9G9 mAb was present solely in ejaculated spermatozoa and the testis. I9G9 mAb did not agglutinate or immobilize sperm but inhibited the penetration of zona-free hamster ova by human sperm.

Acrosome↗
PubMed1994

Fluid-regulating and sympathoadrenal hormonal responses to peak exercise following cardiac transplantation.

Orthotopic heart transplantation results in cardiac denervation that can disrupt the normal regulation of hydromineral balance. This study compared the exercise-induced variations in plasma osmolality; atrial natriuretic peptide (ANP), arginine vasopressin (AVP), norepinephrine (NE), epinephrine (E), and dopamine (DA) concentrations; and plasma renin activity (PRA) of six cardiac transplant recipients (HTX) and six healthy age-matched controls (C) submitted to graded upright maximal cycling. Venous blood samples were obtained at rest, at submaximal (70% O2 uptake) and peak exercise, and after 10 and 30 min of sitting recovery. Peak O2 uptake was not different between groups despite lower maximal heart rate in HTX (136 +/- 6 vs. 183 +/- 9 beats/min). Baseline plasma ANP and PRA were higher in HTX (203 +/- 55 pg/ml and 29.9 +/- 7.4 ng.ml-1 x h-1) than in C (71 +/- 17 pg/ml and 5.4 +/- 0.96 ng.ml-1 x h-1); AVP was lower in HTX than in C (1.1 +/- 0.3 vs. 3.2 +/- 0.8 pg/ml; P < 0.05); and circulating E, NE, and DA were not different between groups. Exercise resulted in more marked increases in HTX than in C for ANP (300 vs. 100%), AVP (2,000 vs. 300%), NE (860 vs. 500%), and DA (611 vs. 187%) but not for PRA and a higher E response in C than in HTX (455 vs. 1,258%). These observations confirm that the potential for ANP release to central volume loading is independent of intact cardiac innervation. The exaggerated AVP response in HTX could, however, reflect the absence of inhibitory influences consecutive to denervation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex Hormones↗
PubMed1994

Cardiac and central nervous system vasculitis in a child with dermatomyositis.

Cerebral vasculitis and clinically important myocardial inflammation are rare in juvenile dermatomyositis. We report a previously healthy 6-year-old girl with dermatomyositis who died after a fulminating clinical deterioration. Postmortem examination of the heart revealed characteristic endothelial tubuloreticular aggregates and evidence of capillary necrosis and secondary thrombosis, associated with extensive hemorrhagic myocardial necrosis. Endothelial necrosis was also evident in the cerebrocortical capillaries.

Autopsy↗
PubMed1994

Sources of lead exposure in Mexico City.

Many countries, including Mexico, are facing a largely unrecognized epidemic of low-level lead poisoning. Mexico is the sixth largest lead-producing country in the world, and 40% of its production is used locally in different industrial processes that cause lead contamination of the environment. The major sources and pathways of lead exposure among the Mexican population are gasoline emissions, lead-glazed ceramics, leaded paint, and lead in canned foods and beverages. In this paper we present evidence for the presence of lead in different environmental media and its impact on blood lead levels of the Mexican population. Although during the last few years important measures have been implemented to decrease lead exposure, our findings suggest that lead poisoning is still an important problem in Mexico. There is an urgent need for regulatory policies that implement stricter control to protect the Mexican population. There is also a need to develop adequate programs to reduce the lead burden and the associated health effects in the population that has been chronically exposed.

Ceramics↗