Search PubMed⌕ Search

Biomedical subjects

M Perez

Publications and source records attributed to M Perez.

At least 109 records · Page 6Linked to original sources
PubMed1995

The enhancement of growth of a syngeneic plasmacytoma in BALB/c mice by pristane priming is not due to immunosuppressive effects on antibody-forming cell or mitogen-responsive splenocytes.

The effects of pristane on some immunity parameters in BALB/c mice were studied. The intraperitoneal administration of a single dose of pristane induced a strong inflammatory reaction that lasted longer than 10 days. When mice were immunized with sheep erythrocytes 10 days after pristane administration, the response of hemolytic IgM-forming cells was increased and that of hemolytic IgG-forming cells was decreased; however, the total number of antibody-forming cells did not change. The proliferative response of splenocytes to concanavalin A was increased in mice that received pristane 10 days earlier. Development of the syngeneic NS1 plasmacytoma was enhanced by administration of pristane 2 days or 10 days before tumor transplantation. We concluded that enhancement of plasmacytoma development was not due to immunosuppressive properties of pristane but to other factors such as ascites induction.

Animals↗
PubMed1995

Application of a colorimetric method to the determination of the protein content of commercial foods, mixed human diets and nitrogen losses in infantile diarrhoea.

Recently we reported on the application of a method for protein determination which measures nitrogen in Kjeldahl digests colorimetrically. This procedure has the advantage of eliminating the distillation and titration steps of the Kjeldahl method and it is ideal for nutritional studies, since many samples can be run in a single day. Accordingly, the purpose of the present report was to extend the application of this method to the determination of the protein content of commercially available foods such as dairy products, dry cereals or cereal based products and legumes and also to evaluate this method in the determination of the protein content of the mixtures of cooked foods served during lunch at the cafeteria of the Universidad Simón Bolívar, Caracas. In both cases the results of the colorimetric nitrogen agreed very well with those obtained by the macro Kjeldahl, indicating that the colorimetric method may be used in monitoring the protein content of commercial foods and in evaluating the protein offered in institutional food services. Finally, to further demonstrate the value of this method in clinical trials, we used it to monitor the daily nitrogen intake and nitrogen losses in 43 male young children with acute diarrhoea, and 15 with persistent diarrhoea fed liquid formulae, and showed that protein digestibility and retention were higher in persistent than in acute diarrhoea. The severity of acute diarrhoea affected negatively (r = -0.62) the percentage of protein absorbed, whereas the protein absorbed (r = 0.70) and retained (r = 0.55) correlated positively with protein consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Colorimetry↗
PubMed1995

The product of Zfp59 (Mfg2), a mouse gene expressed at the spermatid stage of spermatogenesis, accumulates in spermatozoa nuclei.

We have described previously three mouse multifinger coding genes (C. Passananti et al., Proc. Natl. Acad. Sci. USA, 86: 9417-9421, 1989). We have analyzed the expression of one of them, termed Mfg2 and renamed Zfp59, and demonstrated that Zfp59 mRNA and its translation product are present in specific stages of mouse spermatogenesis. The predicted amino acid sequence of the Zfp59 protein has been found to consist of 16 zinc-finger motifs clustered at the COOH terminus and subdivided into two groups by a degenerate finger motif. At its NH2 terminus, Zfp59 shares with other members of the zinc finger gene family two additional conserved amino acid modules A and B, described as either FAX, KRAB, or FPB domains. By means of Northern blot, Western blot analysis, and immunohistochemical localization, Zfp59 mRNA and its translation product were shown to be synthesized specifically during the postmeiotic phase of male germ line differentiation. By immunoelectron microscopy, the Zfp59 protein has been shown to accumulate in the nuclei of mature sperms in association with the nuclear matrix.

Amino Acid Sequence↗
PubMed1994

Intense vascular sprouting from rat femoral vein induced by prostaglandins E1 and E2.

The formation of new capillaries from the rat femoral vein was specifically explored to assess whether venous vessels of this caliber may participate in the process of angiogenesis. Prostaglandins of the E series (PGE1 and PGE2) were administered into the soft connective tissue surrounding the rat femoral vessels as angiogenic inducers. In these conditions, between 2 and 7 days, a great number of new capillaries were observed in the media of the femoral vein, arising from the endothelial cells (EC) in the intima. The events of the capillary growth from the femoral vein included EC activation, local degradation of the basal membrane followed by migration and proliferation of EC, solid sprout formation with posterior canalization, development of a new basal membrane, and appearance of pericytes around the new capillary. Although numerous vascular buds were also observed arising from the small venules and capillaries in the periadventitial tissues, they were separated at first from those in the media of the femoral vein by the venous adventitia. Later, connections were observed between both newly formed microcirculations. The present study shows the capacity of PGE1 and PGE2 in the extravascular position of inducing capillary sprouting from veins. Furthermore, the observations provide greater evidence that vessels with characteristics similar to those of the rat femoral vein may contribute to angiogenesis, on occasion with an intense neovascularization. This fact may be of interest for the establishment of a functional circulation after angiogenesis by anastomoses of the new capillaries with those arising from pre-existing vessels of greater caliber than the venules.

Alprostadil↗
PubMed1994

Group psychotherapy with spinal cord injured substance abusers.

Some studies have suggested that nondisabled people follow the dictates of a 'kindness norm' when reacting to those who are disabled. Spinal cord injured substance abusers have sometimes used the kindness of others to help maintain their addictive behavior. A special unit for such substance abusers in a Veterans Affairs hospital has used group psychotherapy as one of the principal methods for moving beyond the kindness norm and challenging its patients to struggle with their substance abuse. Therapists in this group have had to become aware of the special content of denial in this population, of the role of physical problems specific to spinal cord injury, and of the need to set aside clinical issues at times in order to make on the spot responses to practical problems associated with the injury.

Denial, Psychological↗
PubMed1994

Is triple contrast computed tomographic scanning useful in the selective management of stab wounds to the back?

We devised a protocol to prospectively manage stab wounds to the back with the hypothesis that the triple contrast computed tomographic (CT) scan is an effective means of detecting occult injury in these patients. All wounds to the back in hemodynamically stable adults were locally explored. All patients with muscular fascial penetration underwent triple contrast CT scanning utilizing oral, rectal, and IV contrast. Patients did not undergo surgical exploration if their CT scan was interpreted as negative or if the CT scan demonstrated injuries not requiring surgical intervention. Fifty-three patients were entered into the protocol. The time to complete the triple contrast CT scan ranged from 3 to 6 hours at a cost of $1050 for each scan. In 51 patients (96%), the CT scan either had negative findings (n = 31) or showed injuries not requiring exploration (n = 20). These patients did well with nonsurgical management. Two CT scans documented significant injury and led to surgical exploration and therapeutic celiotomies. Although triple contrast CT scanning was able to detect occult injury in patients with stab wounds to the back it did so at considerable cost and the results rarely altered clinical care. Therefore, its routine use in these patients is not recommended.

Back↗
PubMed1994

[Free latissimus dorsi flap revascularized by double venous graft on the femoral trifurcation in the treatment of lumbar radionecrosis. Apropos of 2 cases].

Two patients were operated in 1989 and 1992 for lumbar chronic osteoradionecrosis (toxi-infection collapsus in one of the two cases). Conventional coverage procedures (skin graft, local flaps) or distally based latissimus dorsi musculo-cutaneous flap (second case) were attempted but failed. So we realised in a one stage procedure a free musculo-cutaneous flap in the case no. 1 and a free muscular flap, later skin grafted, in the case no. 2. Venous and arterial bypass were provided by 40 cm long saphenous veins harvested from the thighs, and allowed to reach the lumbar site with proximal anastomosis performed on the femoral artery. The results were considered to be excellent. That short experience shows that long venous bypass with microsurgical free transfer can be safely performed. This results in an extremely high flow shunt.

Adult↗
PubMed1993

Anatomic basis of the physiopathology of the epicondylalgias: a study of the deep branch of the radial nerve.

Compression of the deep branch of the radial n. during its passage through Fröhse's arcade in the supinator m. is one of the classical explanations advanced for epicondylalgia. The object of this study was to define the anatomy of the deep branch of the radial n. from its origin up to the origin of the branches to the lateral epicondylar mm. 34 upper limbs were dissected and three segments of the deep branch of the radial n. were distinguished: segment I, from its origin to its entry into the supinator m.; segment II, corresponding to its passage through the supinator m.; and segment III, extending from its exit from the supinator m. to the origin of the nn. to the lateral epicondylar mm. The lengths of these three segments were defined, as well as the level of division of the radial n. in relation to the joint-line, the thickness of the arcade of the supinator m., and the number of nerve branches to the supinator m. It was found that segment III is closely related to the radial head, around which it winds in supination and extension. The three nerve segments thus defined were studied separately microscopically for evidence of lesions. The results were as follows. Segment I: absence of any marked histologic lesions; segment II: marked fibrous thickening of the perineurium and the interstitial connective tissue, replacing certain nerve fibers; segment III: persistence of moderate interstitial fibrosis. These findings appeared constant in all the specimens examined. These results indicate that the deep branch of the radial n. is most affected during its passage through the supinator m.(ABSTRACT TRUNCATED AT 250 WORDS)

Forearm↗
PubMed1993

Effect of anthelmintic treatment on the allergic reactivity of children in a tropical slum.

It is well known that helminthic infection can cause a polyclonal stimulation of the synthesis of IgE, which is dependent on interleukin-4 (IL-4) production, and it has been suggested that this can modulate the expression of allergic reactivity in tropical populations. We evaluated the effect of regular anthelmintic treatment, for a period of 22 months, on certain aspects of the allergic reactivity of children in a slum area of Caracas, Venezuela, where helminths are endemic. The treatment (Oxantel-Pyrantel; Quantrel) effectively eliminated intestinal helminthic infection and resulted in a significant decrease in the initially elevated total serum IgE levels. IL-4 was detectable in the serum, and a significant reduction in IL-4 was also observed after treatment. In contrast, both the immediate-hypersensitivity skin-test reactivity and serum levels of specific IgE antibody against environmental allergens were markedly increased in the treated children. In a group of children who were also evaluated in the same slum, but who declined treatment, a substantial increase in helminthic infection occurred, which was related to an acute deterioration of the socioeconomic conditions of Venezuela over the course of our study period. This was paralleled by a considerable increase in total IgE levels in these children and a decrease in the skin-test reactivities and specific IgE levels. The application of Prausnitz-Küstner passive transfer tests and analysis of specific IgE antibody levels indicated that the polyclonal stimulation of IgE synthesis by helminthic parasites results in mast cell Fc epsilon receptor saturation and suppression of specific IgE antibody synthesis. This inhibition of allergic reactivity is reversible by anthelmintic treatment.

Adolescent↗
PubMed1993

An outbreak of mupirocin-resistant Staphylococcus aureus on a dermatology ward associated with an environmental reservoir.

OBJECTIVE: To investigate a cluster of mupirocin-resistant Staphylococcus aureus on a dermatology ward. DESIGN: An outbreak of mupirocin-resistant S aureus was noted on the dermatology ward during a prospective epidemiologic study of methicillin-resistant S aureus (MRSA) and borderline methicillin-susceptible S aureus (BMSSA). Pulsed-field gel electrophoresis (PFGE) of whole-cell DNA digested with Sma I was used as a marker of strain identity. SETTING AND PATIENTS: An 850-bed university hospital with a 12-bed inpatient dermatology ward. Most patients have severe, exfoliating dermatologic disorders. RESULTS: MRSA or BMSSA were isolated from 13 patients on the dermatology ward over a 14-month period. Eleven of these isolates (84.6%) were mupirocin-resistant. Nine isolates were present on admission (81.8%); 8 of these patients had been hospitalized on the same ward within the last two months. Nasal and hand cultures from 36 personnel were negative for mupirocin-resistant MRSA or BMSSA. Extensive environmental culturing revealed that a blood pressure cuff and the patients' communal shower were positive for mupirocin-resistant BMSSA. PFGE of all mupirocin-resistant isolates demonstrated that the nine patients and both environmental sources had identical DNA typing patterns. INTERVENTIONS: Changing of blood pressure cuffs between patients and more stringent cleaning of communal areas was initiated. Repeat environmental cultures were negative. CONCLUSIONS: S aureus is not usually associated with an environmental reservoir; however, these patients all had severe desquamation, which may have prolonged environmental contamination.

Blood Pressure Determination↗
PubMed1992

Epidemiology and long-term consequences of hepatitis delta virus infection in the Yucpa Indians of Venezuela.

To define better the epidemiology and clinical impact of hepatitis delta virus (HDV) infection among hepatitis B virus (HBV) carriers in less developed countries, the authors prospectively studied a cohort of 216 Yucpa Indian HBV carriers in Venezuela. HBV carriers were followed regularly between 1983 and 1988 by physical examination, laboratory testing for liver enzymes and HBV and HDV markers, and epidemiologic history. Among the cohort, 74 (34%) were initially positive for HDV infection, and 35 additional persons became infected during the study. Risk factors for new HDV infection included living in southern Yucpa villages; being young adults (15-19 years) or young children (1-9 years), and living in a household with a person with acute HDV infection. Persons with HDV infection were at high risk of developing chronic liver disease; 56% of HDV-infected persons had moderate-to-severe chronic liver disease at the end of the study compared with none of the HBV carriers without HDV infection. Mortality rates were 6.9% and 8.8% per year, respectively, among initially HDV-positive HBV carriers and those with new HDV infection, because of rapidly progressive chronic liver disease and fulminant hepatitis; mortality was significantly lower in HBV carriers without HDV infection and in non-HBV carriers. HDV superinfection is a devastating disease in HBV carriers in tropical South America. Prevention of HBV infection with hepatitis B vaccine is the best available tool to reduce the impact of this problem.

Acute Disease↗
PubMed1992

Development and hormonal regulation of mast cells in the Harderian gland of Syrian hamsters.

The morphological features and relative number of mast cells per mm2 were studied in the Harderian glands of male and female Syrian hamsters (Mesocricetus auratus) under different experimental conditions. The structural and ultrastructural characteristics of Harderian mast cells corresponded to those of connective tissue mast cells. The Harderian glands from female hamsters contained more mast cells than those of male hamsters. A subcutaneous implant of testosterone (2 mg/24 mg beeswax) resulted in a rapid decrease in the number of recognizable mast cells 6 h after the implantation. Neither orchidectomy nor ovariectomy significantly altered the relative number of mast cells. However, the daily subcutaneous injection of 20 IU of human chorionic gonadotropin during 20 days resulted in a significant decrease of identifiable mast cells. The administration of another steroid such as progesterone or the induction of states of hypo- and hyperthyroidism did not alter the distribution of mast cells in the Harderian glands of female Syrian hamsters.

Age Factors↗
PubMed1992

Correlations of unique clinical, immunotypic, and histologic findings in cutaneous gamma/delta T-cell lymphoma.

Cutaneous T-cell lymphoma is a malignancy of T cells that express a clone-specific heterodimer T-cell receptor for antigen. The second recognized case of an epidermotropic malignancy of T-cells expressing gamma/delta T-cell receptor-expressing cells is reported. The immunophenotype of the malignant T-cells was CD3+, CD2+, CD7+, gamma/delta T-cell receptor+, CD4-, CD8-, and alpha/beta T-cell receptor-. The clinical features were remarkable for extreme epidermotropism with a scant dermal lymphomatous infiltrate. Profound keratinocyte necrosis occurred in areas of malignant skin infiltrates. Despite cutaneous lesions covering more than 50% of the skin surface of the patient, no adenopathy or splenomegaly was detected. The intense epidermotropism of this patient's gamma/delta T-cell receptor-expressing cells and the putative cytolytic properties of CD4- CD8- gamma/delta contributed to the destruction of epidermis. Remission was induced with a combination of electron beam and extracorporeal photochemotherapy.

Antigens, CD↗
PubMed1992

Treatment of erythrodermic cutaneous T-cell lymphoma with extracorporeal photochemotherapy.

BACKGROUND: This original cohort of patients with erythrodermic cutaneous T-cell lymphoma (CTCL) was reported to have clinical improvement with photopheresis during the 12 months of the original study. No long-term follow-up data have been available to examine the impact of this therapy on the disease. OBJECTIVE: Our purpose was to provide long-term follow-up on the original 29 erythrodermic CTCL patients treated with photopheresis and to compare these results with historical controls. METHODS: Files of patients from the original photopheresis study centers were reviewed and their current status was documented. RESULTS: The median survival of the treated patients was 60.33 months from the date of diagnosis and 47.9 months from the date of the start of photopheresis therapy. A complete remission has been maintained in four of the six patients who achieved complete responses in the original study. The best responses were seen in patients with a lower CD4/CD8 ratio in the peripheral blood at the start of therapy. CONCLUSION: Photopheresis can influence the natural history of erythrodermic CTCL by inducing remissions and prolonging survival with minimal toxicity.

CD4-CD8 Ratio↗
PubMed1992

Effects of a single oral dose of desipramine on postoperative morphine analgesia.

Drugs that block norepinephrine reuptake offer promise as opioid potentiators, because norepinephrine mediates opioid analgesia but not side effects such as sedation or nausea. In a two-by-two factorial design, we randomized 62 inpatients with pain following major surgery to receive either desipramine, 50 mg by mouth, or placebo at 6 a.m. on the first day after surgery. At their first request of pain medication after 8 a.m., they were given intravenous morphine, either 0.033 mg/kg or 0.10 mg/kg. Pain relief and side effects were assessed for 4 hr; peak relief on the visual analog scale (VAS) was the primary outcome variable. Pain relief, side effect scores, and time to remedication were significantly greater with the higher dose than with the lower dose of morphine, verifying assay sensitivity, but desipramine pretreatment did not significantly enhance morphine analgesia. The mean increase in peak VAS relief score after desipramine pretreatment, relative to placebo, was 6%; the 95% confidence interval for this estimate ranged from a 21% reduction to a 34% increase in pain relief. These results differ from a previous report that 1 week of pretreatment with desipramine, 75 mg per day, potentiated postoperative morphine analgesia. We conclude that if desipramine potentiation of opioid analgesia occurs in humans, its demonstration may require higher doses or chronic treatment.

Administration, Oral↗
PubMed1992

New Granada Medium for detection and identification of group B streptococci.

A methotrexate-containing medium for the detection of beta-hemolytic group B streptococci from clinical specimens on the basis of detection of pigment is described. The medium contained peptone, starch, serum, MgSO4, glucose, pyruvate, methotrexate (as pigment enhancer), phosphate-morpholine-propanesulfonic acid buffer, and selective agents. The recovery of beta-hemolytic group B streptococci was comparable to that obtained with selective broth.

Bacteriological Techniques↗