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Biomedical subjects

G Ramirez

Publications and source records attributed to G Ramirez.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effect of potassium concentration in dialysate on total body potassium.

OBJECTIVE: To investigate the effects of the presence/absence of potassium in the dialysate on total body potassium content in stable hemodialysis patients. DESIGN: Randomized selection. SETTING: Outpatient chronic hemodialysis unit at the James A. Haley VA Hospital in Tampa, Florida. PATIENTS: Six adult hemodialysis patients (mean age 48 +/- 11.61 years, range 32-65 years) participated in this study. They were all males, four African-Americans and two Caucasians. INTERVENTION: Subjects in a random order received dialysis using a dialysate containing no potassium for 3 months, followed by a 2 mEq/L of potassium for another 3 months. Total body potassium measurements and routine blood analysis were taken at baseline and after each three month period. All subjects received diet instruction pre and monthly on a 3 g/day potassium dietary restriction. MAIN OUTCOME MEASURED: There were no significant differences in the amount of total body potassium concentration between the two different dialysates containing 0 or 2 mEq/L potassium. Mean values of serum albumin were significantly higher when the subjects were dialyzed on a 0 potassium bath. CONCLUSION: The use of dialysate containing 0 or 2 mEq/L potassium concentration does not make a significant difference with regard to total body potassium concentration and maybe advantageous for the patients in terms of more freedom in nutritional intake as demonstrated by a significant increase in serum albumin when they were dialyzed on a 0 potassium bath.

Adult↗
PubMed1998

Effects of guanine nucleotides on glutamate-induced chemiluminescence in rat hippocampal slices submitted to hypoxia.

Glutamate significantly increased levels of spontaneous chemiluminescence (CL) in rat hippocampal slices incubated under hypoxic conditions. Although it has been previously shown that guanine nucleotides (GN) displace glutamate from several of its receptors, in our study only GMP, as well as the glutamate antagonist MK-801, was able to reverse the increase in CL provoked by glutamate. On the other hand, not only GTP or Gpp(NH)p failed to reverse the action of glutamate, but they increased CL production like glutamate. This effect of GTP/Gpp(NH)p was also reversed by GMP. We concluded that, under neurotoxic conditions, GMP acted as an antagonist and GTP or Gpp(NH)p acted as agonists of glutamate. These results reinforced the evidence of the existence of extracellular site(s) for GN and indicated a possible role for GN in excitotoxicity.

Animals↗
PubMed1998

Role of IL-1 in renal ischemic reperfusion injury.

Interleukin-1 (IL-1) is a central component of many acute inflammatory processes. Blocking IL-1 receptor (IL-1R) with IL-1R antagonist (IL-1Ra) has attenuated ischemic reperfusion injury in brain, heart, and liver models. However, the role of IL-1 in renal ischemic reperfusion injury (IRI) is not known. Therefore, the role of IL-1 in renal IRI was evaluated using the complementary approaches of IL-1R blockade in wild-type mice in addition to the study of renal IRI in IL-1R knockout (KO) mice. Ischemia was induced by bilateral renal pedicle clamping for 30 min. IL-1Ra was administered at 10 mg/kg every 4 h, high doses that have been protective in previous organ injury models in mice. IL-1R KO animals, previously characterized as insensitive to IL-1, had the absence of IL-1R1 confirmed by DNA blots. IL-1Ra, IL-1R KO, and control groups had similar elevations of blood urea nitrogen (114 +/- 13, 133 +/- 11, and 120 +/- 11 mg/dl) and serum creatinine (1.7 +/- 0.3, 2.1 +/- 0.2, and 1.6 +/- 0.3 mg/dl) 24 h after ischemia. Furthermore, acute tubular necrosis scores were also similar in IL-1Ra-treated mice (3.0 +/- 0.3), IL-1R KO mice (2.7 +/- 0.3), and control mice (3.1 +/- 0.2). However, both IL-1Ra and IL-1R KO groups, compared with control animals, developed significantly less infiltration of polymorphonuclear leukocytes per 10 high-power fields in postischemic renal tissue (1111 +/- 228 and 967 +/- 198 versus 1820 +/- 190, P < 0.05). In contrast to the comparable renal functions at 24 h, recovery of renal function was significantly accelerated in the IL-1R KO group compared with control at both 48 (P < 0.05) and 72 (P < 0.05) h. Recovery in the IL-1Ra group was similar to that in the control animals. These data demonstrate that IL-1 is unlikely to be beneficial in the recovery of renal function after ischemia and may play a deleterious role.

Analysis of Variance↗
PubMed1998

The leukointegrin alpha d/beta 2 (alpha d/CD18): specific changes in surface expression in patients on hemodialysis.

Alpha d/CD18 is a newly discovered leukocyte adhesion molecule with sequence homology to CD11a, b and c of the beta 2 integrin family. Little is known about alpha d expression in vivo, particularly how it compares with the other beta 2 integrins. Previous studies have demonstrated that beta 2 integrin expression, particularly CD11b, is upregulated in vivo during hemodialysis (HD) with complement activating membranes. These changes may contribute to the immunologic abnormalities seen in HD patients. Given the well described changes of beta 2 integrins in these patients, we hypothesized that alpha d expression could also be altered by HD. Using flow cytometry with two specific antibodies to alpha d, alpha d expression in healthy adults (n = 16) was compared on macrophages (MO) > polymorphonuclear cells (PMNs) > lymphocytes (LY). Phorbol ester treatment of leukocytes in vitro significantly increased expression on MO and PMN, but not LY. Chronic HD patients at baseline (n = 15) had elevated (P < 0.05) alpha d mean channel fluorescence (MCF) on MOs, PMNs and LYs compared to normals. PMN alpha d MCF increased at 15 min into HD, but then returned to baseline levels at 180 min. Alpha d MCF for LYs decreased at 180 min, while MOs levels were unchanged. Alpha d expression is increased in chronic renal failure and further regulated by hemodialysis, but with unique characteristics compared to the other beta 2 integrins. Alpha d may be important in abnormal cell-cell contacts in renal failure.

Adult↗
PubMed1998

Treatment of depression--newer pharmacotherapies.

OBJECTIVES: Depressive disorders are persistent, recurring illnesses that impose enormous personal suffering on individuals and their families. Major depression alone is estimated as the fourth most important cause of worldwide loss in disability-adjusted life years and is likely to become the second most important within 20 years. A continued quest for more effective treatments has spawned newer antidepressants and herbal treatments, which have contributed to explosive growth in antidepressant prescribing, increasing pharmacy costs, and wider but sometimes confusing choices for clinicians and patients. This evidence report provides a comprehensive evaluation of the benefits and adverse effects of newer pharmacotherapies and herbal treatments for depressive disorders in adults and children. SEARCH STRATEGY: Pertinent literature from 1980 to January 1998 was identified from a specialized registry of controlled trials, meta-analyses, and experts. The registry contained trials addressing depression that had been identified from multiple electronic bibliographic databases, hand searches of journals, and pharmaceutical companies. The search, which yielded 1,277 records, combined terms "depression," "depressive disorder," or "dysthymic disorder" with a list of 32 specific "newer" antidepressant and herbal treatments. SELECTION CRITERIA: Randomized controlled trials were reviewed if they (1) were at least 6 weeks in duration; (2) compared a "newer" antidepressant with another antidepressant (newer or older), placebo, or psychosocial intervention; (3) involved participants with depressive disorders; and (4) had a clinical outcome. Two or more independent reviewers identified 315 trials that met these criteria. DATA COLLECTION AND ANALYSIS: Two persons independently abstracted data from each trial. Data were synthesized descriptively, paying attention to participant and diagnostic descriptors, intervention characteristics, study designs and clinical outcomes. Some data were analyzed quantitatively using an empirical Bayes random-effects estimator method. Primary outcomes were response rate, total discontinuation rates (dropouts), and discontinuation rates due to adverse events. Response rates were defined as a 50 percent or greater improvement in symptoms as assessed by a depression symptoms rating scale or a rating of much or very much improved as assessed by a global assessment method. MAIN RESULTS: There were 264 trials that evaluated antidepressants in patients (adults and children) with major depression. Of these, 81 compared newer agents with placebo, 150 newer with older agents, 32 newer agents with newer agents, and 1 newer agent with psychotherapy. There were 14 trials evaluating hypericum (St. John's wort), 27 trials each in primary care patients and older adults, 10 trials limited to patients with specific concomitant illnesses, 9 trials in patients with dysthymia, 3 trials each in patients with mixed anxiety depression and subsyndromal depression, 2 trials in adolescents, and 1 in the postpartum setting. Most trials were conducted in outpatients and examined only acute phase treatment of less than 12 weeks' duration. Newer antidepressants were more effective than placebo in treating major depression (risk ratio 1.6, 95% CI 1.5 to 1.7) and dysthymia (risk ratio 1.7, 95% CI 1.3 to 2.3). They were effective among older adults and in primary care patients. In general, there were no significant differences in efficacy among individual newer agents or between newer and older agents. Hypericum (St. John's wort) was more effective than placebo in treating mild to moderately severe depressive disorders (risk ratio 1.9, 95% CI 1.2 to 2.8). Whether hypericum (St. John's wort) is as effective as standard antidepressant agents given in adequate doses was not established. No significant differences were found between newer and older antidepressants in overall discontinuation rates. Selective serotonin reuptake inhibitors (SSRIs), reversi

Adult↗
PubMed1998

Partial renal resistance to arginine vasopressin as an adaptation to high altitude living.

BACKGROUND: The normal physiological response to high altitude (HA) is a decrease in total body water (TBW) and plasma and extracellular volume. The present investigation was designed to determine the mechanisms of the decrease in TBW with HA adaptation. METHOD: There were 10 men from the Southern Colombian Andes (2600 m) in Pasto, Colombia, who were compared to age-matched men from sea level (SL), Tampa, FL, in the U.S., with respect to their TBW, ability to handle a water load and response to exogenous arginine vasopressin (AVP). Measurements included circulating AVP, atrial natriuretic peptides [atrial natriuretic factor (ANF) and vessel dilator], and urinary excretion of the AVP sensitive water channel, aquaporin-2 (AQP2). RESULTS: The HA subjects had significantly (p < 0.01) lower TBW (29.37 +/- 0.98 vs 39.71 +/- 1.66 Kg), AQP2 excretion and vessel dilator circulating levels at baseline compared to SL subjects. ANF levels were not significantly different between the two groups. With water loading (20 ml.kg-1 in 15 min) there was a rapid increase in urine volume at 30 min with a decline thereafter in HA subjects while SL subjects had a gradual increment peaking at 120 min. There was a significant (p < 0.05) decrease in plasma AVP in the SL subjects within 30 min after the water load while the HA subjects had no significant decrease in AVP levels. Excretion of AQP2 decreased significantly after the water load only in the SL subjects. Administration of exogenous AVP increased AQP2 3- to 4-fold in the HA in comparison to SL subjects. CONCLUSIONS: Present data demonstrate the following adaptations to HA: decrease in TBW, better ability to handle a water load despite high levels of AVP, a significant decrease in the circulation of vessel dilator, and diminished excretion of AQP2 water channel. These findings indicate an insensitivity of the collecting duct of HA subjects to the actions AVP. However, exogenous administration of AVP caused a marked excretion of AQP2.

Acclimatization↗
PubMed1997

Are the clinical effects of homeopathy placebo effects? A meta-analysis of placebo-controlled trials.

BACKGROUND: Homeopathy seems scientifically implausible, but has widespread use. We aimed to assess whether the clinical effect reported in randomised controlled trials of homeopathic remedies is equivalent to that reported for placebo. METHODS: We sought studies from computerised bibliographies and contracts with researchers, institutions, manufacturers, individual collectors, homeopathic conference proceedings, and books. We included all languages. Double-blind and/or randomised placebo-controlled trials of clinical conditions were considered. Our review of 185 trials identified 119 that met the inclusion criteria. 89 had adequate data for meta-analysis, and two sets of trial were used to assess reproducibility. Two reviewers assessed study quality with two scales and extracted data for information on clinical condition, homeopathy type, dilution, "remedy", population, and outcomes. FINDINGS: The combined odds ratio for the 89 studies entered into the main meta-analysis was 2.45 (95% CI 2.05, 2.93) in favour of homeopathy. The odds ratio for the 26 good-quality studies was 1.66 (1.33, 2.08), and that corrected for publication bias was 1.78 (1.03, 3.10). Four studies on the effects of a single remedy on seasonal allergies had a pooled odds ratio for ocular symptoms at 4 weeks of 2.03 (1.51, 2.74). Five studies on postoperative ileus had a pooled mean effect-size-difference of -0.22 standard deviations (95% CI -0.36, -0.09) for flatus, and -0.18 SDs (-0.33, -0.03) for stool (both p < 0.05). INTERPRETATION: The results of our meta-analysis are not compatible with the hypothesis that the clinical effects of homeopathy are completely due to placebo. However, we found insufficient evidence from these studies that homeopathy is clearly efficacious for any single clinical condition. Further research on homeopathy is warranted provided it is rigorous and systematic.

Double-Blind Method↗
PubMed1997

A woman with abdominal pain and a history of thromboses.

A 39-year-old woman presented with progressively severe, sharp abdominal pain of three days' duration. The pain originated in the right lower quadrant of the abdomen and radiated to the back and suprapubic area. It worsened on ambulation and was associated with nausea and loose stools.

Abdominal Pain↗
PubMed1997

A naturally occurring mutant human epidermal growth factor receptor as a target for peptide vaccine immunotherapy of tumors.

The type III EGF receptor (EGFRvIII) is the result of an in-frame deletion from nucleotides 275 to 1075 in the EGF receptor cDNA sequence creating a novel epitope at the fusion junction. This spontaneously occurring alteration is found in a high percentage of primary human brain, breast, lung and ovarian tumors. We have explored whether a peptide derived from the fusion junction could serve as the basis for an antitumor vaccine. Preimmunization of mice with this peptide substantially inhibited tumor formation by cells expressing EGFRvIII. Tumor cell inoculation followed by immunization could also enhance the regression of existing tumors. Antibody production was elicited in animals that was highly specific for the novel epitope and also a CTL response that was mediated by CD8+ T lymphocytes. The alteration present in EGFRvIII could serve as the basis for an antitumor vaccine with potentially wide application in humans.

3T3 Cells↗
PubMed1997

Molecular modeling of (E)-1-alkyl-4(3)-[2-(1H-azolyl)vinyl]-pyridinium salts and evaluation of their behavior towards choline acetyltransferase.

A new type of extended pi-system aza-analogue of (E)-4-[2-(1-naphthylvinyl)]-1-substituted pyridinium salts (NVP+) has been designed and its inhibitory activity towards choline acetyltransferase (ChAT) has been evaluated in vitro. Among the several examples of the title quaternary salts synthesized 2 and 3, the indolylvinylpyridinium salt 2e is the only one to show a very low ChAT inhibition. The molecular modeling study is highly illustrative of their behavior towards ChAT and interaction with the recognition site. Thus, several selected cations together with the reference NVP+ compound 1a were studied at the PM3 and AM1 levels respectively. At the global minima, all the compounds are planar, which, from the electron charge distribution, shows a degree of polarization similar to the NVP+ model compound 1a. However, the fitting of all optimized structures indicated that only the indole derivative 2e showed the same aromatic fragment orientation as 1a, which allows us to define a volume that is not accessible to ligands in the enzyme and consequently to a refined model of the choline acetyltransferase recognition site.

Animals↗
PubMed1997

Effect of guanine nucleotides on [3H]glutamate binding and on adenylate cyclase activity in rat brain membranes.

GMP-PNP, a non-hydrolyzable analog of GTP binds tightly to G-protein in the presence of Mg2+, so that the binding is stable even after exhaustive washings. This property was exploited to prepare membrane samples of rat brain where G-protein GTP-binding sites were saturated with GMP-PNP. Experiments carried out with these membranes showed that GTP, GMP-PNP, GDP-S and GMP (1 mM) inhibit the sodium-independent [3H]glutamate binding by 30-40% [F(4,40) = 5.9; p < .001], whereas only GMP-PNP activates adenylate cyclase activity [F(6,42) = 3.56; p < .01]. The inhibition of sodium-independent [3H]glutamate binding occurred in the absence of Mg2+. These findings suggest that guanine nucleotides may inhibit glutamate binding and activate adenylate cyclase through distinct mechanisms by acting on different sites.

Adenylyl Cyclases↗
PubMed1997

The treatment of chronic constipation in adults. A systematic review.

OBJECTIVE: To evaluate whether laxatives and fiber therapies improve symptoms and bowel movement frequency in adults with chronic constipation. DATA SOURCES: English language studies were identified from computerized MEDLINE (1966-1995). Biological Abstracts (1990-1995), and Micromedex searches; bibliographies; textbooks; laxative manufactures; and experts. STUDY SELECTION: Randomized trials of laxative or fiber therapies lasting more than 1 week that evaluated clinical outcomes in adults with chronic constipation. MEASUREMENTS AND MAIN RESULTS: Two independent reviewers appraised each trial's characteristics including methodologic quality. There were 36 trials involving 1,815 persons from a variety of settings including clinics, hospitals and nursing homes. Twenty-three trials were 1 month or less in duration. Several laxative and fiber preparations were evaluated. Twenty trials had a placebo, usual care, or discontinuation of laxative control group, and 16 directly compared different agents. Laxatives and fiber increased bowel movement frequency by an overall weighted average of 1.4 (95% confidence interval [CI] 1.1-1.8) bowel movements per week. Fiber and bulk laxatives decreased abdominal pain and improved stool consistency compared with placebo. Most nonbulk laxative data concerning abdominal pain and stool consistency were inconclusive, though cisapride, lactulose, and lactitol improved consistency. Data concerning superiority of various treatments were inconclusive. No severe side effects for any of the therapies were reported. CONCLUSIONS: Both fiber and laxatives modestly improved bowel movement frequency in adults with chronic constipation. There was inadequate evidence to establish whether fiber was superior to laxatives or one laxative class was superior to another.

Adult↗
PubMed1997

Anatomy of the cranioencephalic structures of the goat (Capra hircus L.) by imaging techniques: a computerized tomographic study.

A topographic study of the cranioencephalic structure was carried out by computerized tomography on Canarian breed adult goats of medium size and weight, with similar cephalic parameters. In this way, transversal, sagittal and horizontal tomographic images were obtained. Identification of the observed anatomic structures represents the basis of this work from which applicable specie data are derived.

Animals↗
PubMed1997

[Pigmented villonodular synovitis of the wrist. Apropos of a case].

The authors presented a case of pigmented villonodular synovitis of the wrist with extrinsic bony defects on opposing articular surfaces, seen after two recurrences following excision surgery. They performed a total synovectomy followed by curettage and autogenous bone grafting of the carpal and radiocubital bone lesions. Four years after the procedure, the patient-a woman aged 44-was symptom-free and there was no objectivable evidence of recurrence. Pigmented villonodular synovitis (PVNS) is an uncommon, benign, chronic process that causes synovial proliferation. Its etiology is unknown. The majority of patients is young to middle-aged adults. Especially the knee but other joints are involved including the hip, ankle, wrist, hand, and foot. Both soft tissue and bone abnormalities occur in PVNS. Magnetic resonance imaging (MRI) shows a heterogenous synovial mass with intermediate and low signal intensity areas on T1 and T2-weighted images, consistent with hemosiderin deposition. Computed tomography defines clearly the extrinsic bone erosions and excavations, which usually exhibit a sclerotic margin, produced by intraosseous invasion of the expanding synovia. After excision recurrence is common, leading eventually to arthrodesis, arthroplasty and even radiation therapy. The etiology of PVNS is controversial. First approach is conservative surgical treatment with total synovectomy and curettage of the osteolytic foyers. Bone grafts are employed for filling the sites of osteolysis. The sensitivity of MRI permits early detection of the process and may obviate the need for radical management options in PVNS.

Adult↗
PubMed1996

St John's wort for depression--an overview and meta-analysis of randomised clinical trials.

OBJECTIVE: To investigate if extracts of Hypericum perforatum (St John's wort) are more effective than placebo in the treatment of depression, are as effective as standard antidepressive treatment, and have fewer side effects than standard antidepressant drugs. DESIGN: Systematic review and meta-analysis of trials revealed by searches. TRIALS: 23 randomised trials including a total of 1757 outpatients with mainly mild or moderately severe depressive disorders: 15 (14 testing single preparations and one a combination with other plant extracts) were placebo controlled, and eight (six testing single preparations and two combinations) compared hypericum with another drug treatment. MAIN OUTCOME MEASURES: A pooled estimate of the responder rate ratio (responder rate in treatment group/responder rate in control group), and numbers of patients reporting and dropping out for side effects. RESULTS: Hypericum extracts were significantly superior to placebo (ratio = 2.67; 95% confidence interval 1.78 to 4.01) and similarly effective as standard antidepressants (single preparations 1.10; 0.93 to 1.31, combinations 1.52; 0.78 to 2.94). There were two (0.8%) drop outs for side effects with hypericum and seven (3.0%) with standard antidepressant drugs. Side effects occurred in 50 (19.8%) patients on hypericum and 84 (52.8%) patients on standard antidepressants. CONCLUSION: There is evidence that extracts of hypericum are more effective than placebo for the treatment of mild to moderately severe depressive disorders. Further studies comparing extracts with standard antidepressants in well defined groups of patients and comparing different extracts and doses are needed.

Antidepressive Agents↗
PubMed1996

Multiple primary malignancies in a renal transplant patient.

Organ transplantation and the use of immunosuppressive therapy has been associated with an increased incidence of malignancy. We report the case of a long-term renal transplant recipient who developed concomitant skin cancers, non-Hodgkin's lymphoma, and malignant fibrous histiocytoma. The development of three seemingly unrelated cancers in the same patient illustrates the favorable host environment in transplant patients for the development of malignancies.

Histiocytoma, Benign Fibrous↗