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Biomedical subjects

R Gutierrez

Publications and source records attributed to R Gutierrez.

At least 55 records · Page 3Linked to original sources
PubMed1992

Neochondrogenesis in the septal area after submucous cartilaginous resection.

The present work was carried out to study cartilaginous repair after subperichondrial resection of the septal cartilage, the fibrous layer of the perichondrium remaining "in situ". In these conditions, after granulation tissue formation, both neochondrogenesis and connective tissue differentiation were observed. Neochondrogenesis was found in defect areas next to the resection borders, and connective tissue formation in those further away. The transition zone between both types of newly-formed tissues showed cells with intermediate characteristics of chondrocytes and myofibroblasts. The findings provide safer proof that new chondrocytes and fibroblasts growing after septal cartilage removal originate largely from a common precursor cell either in the fibrous perichondrial layer or in the connective tissue surrounding it. The peculiar topographic distribution of the newly-formed tissues may be explained by the different effects during respiration of mechanical forces on the septal space, which lacks its cartilaginous support, and on the adjacent remaining cartilage, as well as on the borders of both.

Animals↗
PubMed1992

[Kidney retransplantation: prognostic factors in a series of 84 cases].

Results are presented of a series of 84 patients receiving renal retransplants over the last 12 years. One year survival rate of patients and transplants was 87.6% and 79.1% respectively, compared with 92.5% and 81.2% for the 783 first grafts performed during the same period. Positive prognostic features were the absence of sensitization, survival of the first transplant for more than 6 months, and the inclusion of cyclosporin in the immunodepressive treatment.

Actuarial Analysis↗
PubMed1992

Pericytes as a supplementary source of osteoblasts in periosteal osteogenesis.

In the adult rat femur, lifting a periosteum strip with microscopic bone flakes on its deep surface, if performed without damaging the surrounding microcirculation, rapidly leads to new bone formation and angiogenesis. Using vascular labeling, the pericytes and endothelial cells (ECs) were labeled with monastral blue (MB) in the preformed, preexisting postcapillary venules of the periosteal microcirculation. MB was detectable by light and electron microscopy and it persisted in some of the daughter cells. Between one and 21 hours, the MB labeling was restricted to the pericytes and ECs of postcapillary venules. Immediately afterward, both pericytes and ECs of these vessels were activated and continued to show MB. The phenomenon of pericyte activation includes enlargement, disruption of their basal lamina, separation from the walls of the preformed vessels, and the presence of mitotic figures. At this stage, activated pericytes with MB in their cytoplasm, fibroblast-like cells, and transitional cell forms between them were seen in interstitial areas. After 27 hours, vascular buds appeared and MB was detected in some ECs and pericytes. Between three and six days, when bone-tissue development was observed, some osteoblasts were MB labeled. Previous findings support the hypothesis that when the periosteum is activated, the process of bone formation from cells already present in the periosteum is augmented by proliferation and differentiation of pericytes, which contribute a supplementary population of osteoprogenitor cells.

Animals↗
PubMed1991

Inducible perivascular cells contribute to the neochondrogenesis in grafted perichondrium.

Autogeneic perichondrium was implanted above the cremaster muscle of the rat, and the new formation of two types of cartilage (types I and and II) was confirmed. Also, granulation tissue was observed before the type II cartilage formation. Under these conditions, the contribution to the neocartilage of graft bed derived cells, mainly of the venule pericytes, was studied. To follow the pericyte lineage, we used a marker--Monastral Blue B--the administration of which was based on the principle of vascular labeling. While the perichondrium was kept free, before its implantation, the preformed (preexisting) venules in the cremaster muscle were exclusively labeled with Monastral Blue B, which was incorporated into the cytoplasm of pericytes and endothelial cells. After perichondrium implantation, the following sequence in tracer distribution was demonstrated. During the earlier stages, labeling was restricted to the pericytes and endothelial cells of venules in the graft bed. Later the tracer was observed in some endothelial cells and pericytes of the growing vessels and in fibroblast-like cells of the granulation tissue. Finally, some type II neochondrocytes appeared labeled. Tracer was not found in type I neochondrocytes. The presence of label in type II neochondrocytes demonstrates that they arise from progenitor cells present in the graft bed, principally from small venule pericytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Naloxone effects on the visual evoked potentials recorded from the main and accessory visual pathways of the cat.

1. The effects produced by repetitive i.v. administration of naloxone (1, 2 or 4 mg/kg) on the visual evoked potentials (VEPs) recorded along the main and accessory visual pathways were investigated in a modified "encéphale isolé" cat preparation. 2. Naloxone provoked a progressive amplitude enhancement and latency reduction of some components, depending on the structure analyzed, the dose used and the number of administrations applied. Electroretinogram (ERG) and N1-P1 VEP components of optic chiasm (OCh), lateral geniculate body (LGB) and visual cortex (VC) did not present significant changes. 3. Late-latency components (more than 200 msec) appeared in the VEPs of LGB and VC, mainly when 4 mg/kg were used. 4. Our results suggest that endogenous opioids have a modulatory role in the processing of sensory information at different levels of the visual system.

Animals↗
PubMed1991

Urinary schistosomiasis with cutaneous lesions.

We report a case of urinary schistosomiasis with simultaneous presence of cutaneous lesions in a white male. The literature is reviewed, and the frequency, characteristics and physiopathology are discussed.

Adult↗
PubMed1991

Effect of hypertonic versus isotonic sodium bicarbonate on plasma potassium concentration in patients with end-stage renal disease.

The purpose of the study was to evaluate the potassium-lowering effect of hypertonic versus isotonic sodium bicarbonate (NaHCO3) in patients with end-stage renal disease (ESRD) receiving chronic maintenance hemodialysis. Immediately prior to dialysis, we infused isotonic (1.4%, 150 mEq/l) NaHCO3 in H2O (1 mEq/kg body weight over 2 h) to 10 patients with ESRD. Blood was drawn in heparinized tubes, without the use of a tourniquet, from the angioaccess for Na, K, pH, PCO2, HCO3, and osmolality at baseline (x 3) and after 10, 20, 40, 60, 90, 120, and 180 min of infusion. All patients were acidotic (HCO3 13-21 mEq/l, pH 7.25-7.38) prior to the study. In these patients, plasma HCO3 increased by an average of 3 mEq/l, and plasma K decreased by 0.35 mEq/l at 180 min. Plasma osmolality did not change. In 8 patients, a bolus of hypertonic (8.4%, 1,000 mEq/l) NaHCO3 (1 mEq/kg body weight over 5 min) tended to cause a transient increase in plasma HCO3, an increase in plasma osmolality, and minor changes in the K levels (an initial small and transient albeit significant decrease, followed by a tendency to increase). Finally, plasma K tended to increase in patients receiving infusions of either isotonic (n = 6) or hypertonic (n = 6) sodium chloride. Our data do not support the efficacy of the common practice of administering NaHCO3 for the emergency treatment of hyperkalemia in patients with ESRD receiving maintenance dialysis.

Bicarbonates↗
PubMed1991

Peritonitis after cecal perforation. An experimental model to study the therapeutic role of antibiotics associated with allopurinol and catalase.

This work uses cecal perforation on the rat as a model of intra-abdominal sepsis. Under these conditions, various antibiotics were tested alone or in association with free radical scavengers, such as allopurinol and catalase. It can be concluded that the scavengers were not effective alone, but when combined with antibiotics they rendered good results in the majority of the groups when given postsepsis. Further studies are needed to determine the real role of agents like the free radical scavengers in infectious situations such as the one discussed here.

Allopurinol↗
PubMed1990

Discrimination between HIV-1 and HIV-2-seropositive individuals using mouse monoclonal antibodies directed to HIV transmembrane proteins.

Mouse monoclonal antibodies directed against the transmembrane proteins of HIV-1 or HIV-2 provided site-directed, unambiguous discrimination between HIV-1 and HIV-2 antibody-positive sera, when employed in immunoassays as competitive probes against serum antibodies. These monoclonal antibodies mapped to epitopes outside of the well-characterized immunodominant regions (IDR) of the transmembrane proteins. The monoclonal competitive immunoassay was a superior method for discrimination compared with immunoprecipitation of metabolically radiolabeled HIV envelope glycoproteins, Western blot against viral envelope glycoproteins, or noncompetitive enzyme immunoassays employing HIV recombinant transmembrane proteins or synthetic IDR peptides as serological targets. The monoclonal competitive assay was not affected by antigenic cross reactivity or nonspecific reactivity exhibited by selected serum samples toward envelope proteins or peptides, respectively. Results of the monoclonal competitive immunoassay were supported by results of a peptide inhibition assay employing free IDR peptides in competition with IDR peptides on a solid support for binding of serum antibody. IDR peptide inhibition clearly demonstrated non-cross-reactive antigenic specificity of sera toward either the HIV-1 IDR or the HIV-2 IDR. The monoclonal competitive assay also identified samples containing antibody to both HIV-1 and HIV-2 transmembrane proteins. Analysis of these samples by IDR peptide inhibition indicated they contained two distinct, non-cross-reactive populations of antibodies, one directed to the HIV-1 IDR and the other directed to the HIV-2 IDR.

AIDS Serodiagnosis↗
PubMed1990

Influence of magnesium sulfate-induced hypermagnesemia on the anion gap: role of hypersulfatemia.

Although hypermagnesemia purportedly lowers the anion gap (AG), we have shown previously that increases in the serum concentration of the unmeasured cation (UC) Mg due to therapeutic infusion of MgSO4 are not associated with AG reduction. To assess our hypothesis that increases in serum SO4 (unmeasured anion, UA) offset the effect of elevated serum Mg on the AG, we prospectively studied 11 patients receiving MgSO4 intravenously for toxemia of pregnancy. After 6 h of MgSO4 infusion, serum Mg increased by 2.1 +/- 0.2 (SE) mEq/l (p less than 0.001) without a significant decrease in the AG. Concomitantly, serum SO4 increased by 1.4 +/- 0.2 mEq/l. Comparison of the renal handling of SO4 versus Mg showed a higher fractional excretion of the former, probably accounting in part for the smaller increment of serum SO4 than of Mg. Comparison of the change in serum SO4 minus that of Mg indicated that, on the average, 70% of the observed 1.0 +/- 0.7 mEq/l reduction in AG was accounted for by the observed changes in the two pertinent unmeasured ions. A small decrement in serum Ca probably was a quantitatively minor factor tending to obviate a greater decrease in AG. We conclude that hypersulfatemia attenuates the reduction in AG that would otherwise accompany MgSO4-induced hypermagnesemia.

Acid-Base Equilibrium↗
PubMed1990

Effect of hypercalcemia on the anion gap.

It has been assumed, but not documented, that hypercalcemia induces an appreciable reduction in the serum anion gap (AG) because it represents an increase in the level of unmeasured cations. To test this question, we retrospectively compared the data of 59 hypercalcemic patients with malignancy [group 1, serum Ca 13.3 +/- SE 0.3 mg/dl] with those of 108 patients whose hypercalcemia was of parathyroid origin (group 2, serum Ca 12.1 +/- 0.1 mg/dl), and those of 51 control subjects (group 3, serum Ca 9.5 +/- 0.1 mg/dl). The AG of group 2 subjects (8.7 +/- 0.3 mEq/l) was significantly lower than that of the other two groups (p less than 0.001 for both) despite their higher serum albumin and lower serum Ca in comparison to group 1. The AGs of group 1 (11.1 +/- 0.4 mEq/l) and group 3 (11.1 +/- 0.3 mEq/l) were identical. There was no statistically significant correlation between the AG and serum Ca in the hypercalcemic patients. The major finding that the association of hypercalcemia with reduced AG is seen in hyperparathyroidism, but not in malignancy-related hypercalcemia, is not explained by differences in serum albumin, renal function, or acid-base status. Overlap of values between groups limits the diagnostic usefulness of the AG in an individual patient. Nevertheless, in the absence of multiple myeloma, the finding of an AG of 5 mEq/l or less in a hypercalcemic patient may be a helpful clue suggesting that malignancy is not the etiology.

Acid-Base Equilibrium↗
PubMed1990

The role of the pericytes of the adventitial microcirculation in the arterial intimal thickening.

Segments of rat femoral arteries, with one collateral each, occluded between ligatures and dissected from surrounding tissue, developed intimal thickening, with or without ligation of their collaterals. Numerous newly-formed capillaries from the surrounding arterial microcirculation growing into the adventitia, tunica media and intimal thickening were demonstrated by means of serial longitudinal sections, predominantly in the ostium of the collateral. When the ligatures were applied without damaging the microcirculation surrounding the artery and the normal continuity of the adventitial vessels was unchanged, earlier presence of intimal thickening was observed. When the fibrous layers of the adventitia were removed at the moment of the arterial ligation, the continuity between newly-formed vessels of the neoadventitia and those growing into the media and neointima was much more evident. It was then noted that the pericytes constituted a major component of the intimal thickening. The introduction of contrast material in microcirculation confirmed the connections between newly-formed adventitial and intimal vessels. At the beginning of the experiment, autoradiographic studies showed an increased DNA synthesis in the cells of preformed postcapillary venules and capillaries of surrounding arterial microcirculation and later in those of the newly-formed vessels growing into the arterial wall. These results indicate that newly-formed capillaries derived from surrounding arterial microcirculation penetrate the wall of the occluded arterial segments and contribute to the intimal thickening formation. It is likely that the pericytes and endothelial cells (EC) of these ingrowing vessels are sources of myointimal cells at the intimal thickening and of endothelium at the luminal surface, respectively.

Animals↗
PubMed1989

The effects of administration of lithium salts and magnesium sulfate on the serum anion gap.

Whether or not an increased serum level of an unmeasured cation will reduce the anion gap (AG) depends on concomitant changes (or lack thereof) in serum unmeasured anions. In the present retrospective study, we sought to determine the effect of lithium carbonate or citrate and magnesium sulfate on the AG. Two groups of psychiatric patients whose average serum lithium levels were 0.6 and 1.0 mEq/L were studied. The AG in each group (10.2 +/- 0.3 [SE] and 9.0 +/- 0.4 mEq/L, respectively) was significantly (P less than 0.05) lower than that of a control group (11.1 +/- 0.3 mEq/L). Separately, we collected 87 pairs of AG and serum magnesium data of patients with toxemia of pregnancy. These included those of 15 patients evaluated both before and during magnesium sulfate infusion. Despite an average serum magnesium level of 4.1 +/- 0.2 mEq/L, the AG of the latter subjects tended to increase slightly from 10.8 +/- 0.5 to 11.7 +/- 0.7 mEq/L during magnesium infusion, instead of decreasing. The other data (72 determinations in the 55 patients without preinfusion values) revealed a mean AG of 11.0 +/- 0.3 mEq/L, coexisting with an elevated serum magnesium of 4.1 +/- 0.1 mEq/L. None of the above-mentioned three mean AG values differed significantly from that of the control group. We conclude that hypermagnesemia resulting from the administration of magnesium sulfate does not reduce the AG, probably because of a concomitant and proportional increase in serum sulfate. The present data reemphasize the need to assess the anion gap as the result of concomitant changes in both unmeasured anions and cations.

Acid-Base Equilibrium↗
PubMed1989

The secretory activity of the seminal vesicles and its relationship to sperm motility: effects of infection in the male reproductive tract.

In 146 males aged between 20 years and 40 years attending an infertility service, the secretory activity of the seminal vesicles was assessed by measurement of corrected seminal fructose concentration. This value was related to the presence of a positive semen culture, other evidence of inflammatory processes in the reproductive tract and sperm motility. Only 48% of subjects with a positive semen culture showed evidence of inflammation in the reproductive tract, as assessed by the presence of more than 20 white blood cells per high power field, and greater than 10% spermagglutination in the ejaculate. There was a relationship between the inflammatory process, hypofunction of the seminal vesicles and poor sperm motility. When the semen culture was positive but there was no evidence of inflammation neither seminal vesicle function nor sperm motility was affected. When the semen culture was negative, i.e. no evidence of inflammation and the subjects were asthenozoospermic, the corrected fructose levels were normal. It is proposed that in these conditions the cause of asthenozoospermia may be factors other than accessory sex organ dysfunction. In conclusion, there was no close relationship between the bacteriological results and evidence of inflammation of the accessory glands. A positive semen culture was related to lower levels of corrected fructose (hypofunction of the seminal vesicles) when the positive sperm culture was associated with inflammation of the reproductive tract and asthenozoospermia.

Adult↗
PubMed1988

Growth of two types of cartilage after implantation of free autogeneic perichondrial grafts.

The perichondrium of adult rats was dissected from the posterior side of the ear where a plane of separation can be easily found between the superficial chondrocytes and the rest of the cartilage. When pulled off, the perichondrium brings with it a cartilaginous strip adhered to its inner layer, with the detachment surface showing projections of broken capsular matrix (PBCM). The perichondrium and subperichondrial cartilage were then transferred as autogeneic grafts to preformed muscle pockets of the abdominal wall and to everted vein chambers placed free in the iliac blood flow. During a period of one to 12 days, chondrogenesis was studied in the grafts and in the graft bed areas next to subperichondrial cartilage. When the perichondrium was placed into a muscular pouch, wherein perichondrocytes survived and a prominent vascular ingrowth in the graft bed was observed, the presence of two types of newly formed cartilage was demonstrated (Types I and II). These types showed differences in their location, time of appearance, and microscopic characteristics. Type I neocartilage appeared in the inner layer of the perichondrium on the third or fourth day after grafting; at this time the cells, surrounded by a well-defined capsular matrix, were large, darkly stained, and highly electron dense. Type II neocartilage, separated from Type I by the PBCM, appeared in the graft bed area located within perichondrial folds on the sixth or seventh day after implantation. Their cells showed a poorly defined capsular matrix and were smaller, lighter stained, and less electron dense than those of Type I. When the perichondrium was transplanted to everted vein chambers placed in the iliac blood flow, wherein perichondrocytes survived and vascular ingrowth from the graft bed was not present, Type I neocartilage was formed but Type II was not. The morphologic and histoautoradiographic findings in these studies suggest that Type I cells come from perichondrocytes of the inner perichondrial layer, whereas Type II cells originate from the undifferentiated perivascular mesenchymal cells of the graft bed.

Animals↗
PubMed1987

Investigation of HTLV-3 serology in a renal transplant population.

From June 1977 to March 1985, 572 renal transplants were performed at The University of Texas Medical School at Houston. This represented 220 patients (151 cadaveric [CAD] and 69 living-related donor [LRD] recipients) treated with azathioprine and prednisone (Aza-Pred) and 352 patients (250 CAD and 102 LRD) treated with cyclosporine (CsA) and Pred. Sera from each recipient before and after transplant (Tx) as well as from each of their 436 donors (265 CAD and 171 LRD) were retrospectively tested for the presence of antibody to the human T cell lymphotrophic virus type III (HTLV-3) by enzyme immunoassay (EIA) and Western Blot analysis. Of the 436 donors tested, only 1/265 (0.38%) CAD donors were both EIA repeatedly reactive and Western Blot positive, whereas none of the 171 LRD were reactive. Pre-Tx, 4/401 (1.0%) CAD and 1/171 (0.6%) LRD recipient sera were EIA repeatedly reactive, however, all 5 were to be Western Blot negative. Post-Tx, 4.2% of the sera (24/572, 4 LRD and 20 CAD recipients) were EIA-reactive. All 20 CAD recipient sera were subsequently found to be negative with Western Blot testing. However, 2 LRD sera (2/572, 0.35%) displayed EIA reactivity as well as Western Blot positivity. One LRD, Western-Blot-positive recipient is alive and well with a functioning allograft 39 months post-Tx, whereas the second LRD, Western Blot positive recipient died of septic complications 16 months post-Tx. Finally, the recipient of the Western-Blot-positive CAD allograft is alive with a well-functioning graft and remains EIA and Western-Blot-negative 36 months post-Tx.

Antibodies, Viral↗
PubMed1986

Performance evaluation of the Abbott HTLV III EIA, a test for antibody to HTLV III in donor blood.

An enzyme immunoassay (EIA), designed to detect antibodies to human T-cell lymphotropic virus type III (HTLV III), was evaluated. The antibody test was found to be highly sensitive; serum from 221 of 223 (99.1%) patients with acquired immune deficiency syndrome (AIDS) was positive for antibodies to HTLV III. In addition, the antibody test was found to be highly specific; approximately 99.75% of 20,720 serum or plasma samples from blood donors were negative for antibody to HTLV III. In most cases, the Western Blot analysis agreed well with the EIA. Eighty-one of 82 (98.8%) EIA-positive samples from patients with AIDS were Western Blot positive. Of the EIA-positive blood donors, 21 of 36 (58%) were detected and confirmed by Western Blot analysis. A solid-phase competitive EIA also was evaluated as an alternate procedure. The preliminary results indicate that this immunoassay has a high degree of sensitivity and specificity and could serve as an alternate procedure to detect antibody to HTLV III.

Acquired Immunodeficiency Syndrome↗