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Biomedical subjects

J A Ramirez

Publications and source records attributed to J A Ramirez.

At least 37 records · Page 2Linked to original sources
PubMed1999

Early switch from intravenous to oral antibiotics and early hospital discharge: a prospective observational study of 200 consecutive patients with community-acquired pneumonia.

UNLABELLED: To determine the proportion of patients who can be treated with early switch to oral antibiotics and early discharge, to evaluate clinical outcome and patient satisfaction for patients treated with early switch and early discharge, and to define the factors that interfere with early discharge for some of the patients who underwent early switch to oral antibiotic therapy. DESIGN: Prospective study. PARTICIPANTS: Two hundred consecutive hospitalized patients with community-acquired pneumonia. MAIN OUTCOME MEASURES: Number of days needed to switch to oral therapy and length of hospital stay. Clinical outcome and satisfaction with care were evaluated for those patients treated with early switch and early discharge. RESULTS: Early switch to oral antibiotics (within the first 3 days of hospitalization) was performed in 133 patients (67%). Clinical failure was documented in 1 patient. Early switch and early discharge was performed in 88 patients (44%). The mean length of hospital stay for this group was 3.4 days. The most common reason for prolonged hospitalization after the switch to oral antibiotics was the need for diagnostic workup. More than 95% of patients were satisfied with the care they had received. CONCLUSIONS: Using simple clinical and laboratory criteria, a significant proportion of hospitalized patients with community-acquired pneumonia (44%) can be treated with early switch and early discharge. This model did not affect patient outcome, decreased the length of hospitalization, and was associated with a high level of patient satisfaction.

Administration, Oral↗
PubMed1999

Infection of human endothelial cells with Chlamydia pneumoniae stimulates transendothelial migration of neutrophils and monocytes.

We have previously shown that different isolates of Chlamydia pneumoniae display heterogeneity in the in vitro stimulation of chemokines and adhesion molecules from infected human endothelial cells. In the present study, we examined the ability of different isolates of C. pneumoniae to promote transendothelial migration of neutrophils and monocytes. Human umbilical vein endothelial cells (HUVEC) were infected with low (<15)-passage C. pneumoniae isolates A-03, PS-32, and BR-393 and high (>40)-passage isolates BAL-16, TW-183, and T-2634, and levels of neutrophil and monocyte transendothelial migration were determined following 24 h of infection. Compared to mock-infected controls, significant increases in neutrophil migration were observed in response to most C. pneumoniae isolates examined (P < 0.001). Levels of monocyte migration were significantly increased in response to TW-183 and T-2634 (P < 0.001). Serial passage (>40 times) of the three low-passage isolates in HEp-2 cell cultures prior to infection of HUVEC generally resulted in the promotion of higher levels of neutrophil and monocyte transendothelial migration. These findings were compatible with differences observed in the extent of interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) stimulation between low- and high-passage A-03, PS-32, and BR-393. As opposed to C. pneumoniae, infection with C. trachomatis L2 caused only a slight increase in neutrophil transendothelial migration, which correlated with the lack of measurable IL-8 levels by this species. However, significant levels of monocyte migration were induced in response to C. trachomatis L2 despite a lack of measurable MCP-1 stimulation. C. trachomatis serovars A and E also failed to induce IL-8 and MCP-1 production in HUVEC. Results from this study indicate that the passage history of C. pneumoniae may play a role in the divergence of stimulatory activities observed among isolates in human endothelial cells. In addition, the differences observed between this organism and C. trachomatis suggest that the upregulation of IL-8 and MCP-1 in endothelial cells may be unique to C. pneumoniae.

Adult↗
PubMed1999

Histology and electron microscopy of explanted bifurcated endovascular aortic grafts: evidence of early incorporation and healing.

PURPOSE: To report an examination of explanted bifurcated endovascular aortic grafts for histologic evidence of early healing and incorporation. METHOD: Two bifurcated endovascular aortic grafts composed of polycarbonate urethane and Elgiloy wire were explanted 42 and 21 days after successful endovascular exclusion of abdominal aortic aneurysms. Both patients expired from causes unrelated to endograft deployment. The explanted devices were examined using immunohistochemical analysis and electron microscopy. RESULTS: On explantation, both grafts appeared to have excluded the aneurysm with no evidence of endoleak, graft migration, or thrombosis. Histological examination showed numerous inflammatory cells and good ingrowth of tissue into the proximal 2 cm of the graft. Collagen and smooth muscle cells were evident in the proximal portion of the graft with only collagen in the distal segments. Neointimal formation was seen within the proximal 2 cm also, but not at the distal segments. Macrophages were present in the graft. Scanning electron microscopy showed an extensive matrix of fibers that most likely represented collagen. CONCLUSIONS: Bifurcated endovascular aortic grafts show inflammatory and mild foreign body reactions, collagen formation, and intimal ingrowth during healing. These findings are similar to some of the healing properties reported for sutured grafts, as well as other endovascular grafts.

Actins↗
PubMed1998

Medium molecular weight pentastarch reduces reperfusion injury by decreasing capillary leak in an animal model of spinal cord ischemia.

PURPOSE: The medium molecular weight fraction of pentastarch (HES-Pz) has been shown to decrease reperfusion injury to myocardium and brain by reducing capillary leak. This study was undertaken to assess the effects of HES-Pz on neurologic function, microvascular permeability, and spinal cord infarction after temporary aortic cross-clamping in a rabbit model. METHODS: In 30 New Zealand White rabbits, a snare occlusion device was placed around the infrarenal aorta and tunneled into a subcutaneous position. Animals were allowed to recover for 48 hours and were randomized into three groups. In each group, the infrarenal aorta was occluded by tightening the snare in the awake animal for 21 minutes. Immediately after unclamping, animals received an intravenous infusion of 4% of their estimated blood volume of one of the following solutions: normal saline solution (NS; group 1); 6% standard hydroxyethyl starch (HES), molecular weight 10 to 3400 kD (group 2); and 6% HES-Pz, molecular weight 100 to 1000 kD (group 3). During 5 days of observation, neurologic recovery was graded by an independent observer using the Tarlov scale. Animals were then killed and their spinal cords harvested for histologic examination using hematoxylin-eosin and 2,3,5-triphenyltetrazolium chloride staining. In a separate group of animals (n = 15), the occurrence of spinal cord capillary permeability after NS, HES, and HES-Pz infusions was evaluated by spectrophotometric analysis of extravasated Evans blue. RESULTS: Complete paraplegia and marked histologic evidence of spinal cord cellular injury were seen in 90% of group 1 (NS) and in 78% of group 2 (HES). Treatment with HES-Pz (group 3) resulted in full neurologic recovery in 89% of animals (p < 0.05) and a threefold reduction of extravasated Evans blue compared with controls (p < 0.05). CONCLUSIONS: These results indicate that microvascular hyperpermeability plays an important role in reperfusion injury to the spinal cord. Treatment with HES-Pz reduced the capillary permeability, neuron membrane injury, and incidence of paraplegia after reperfusion of ischemic spinal cord in a rabbit model.

Animals↗
PubMed1998

Suxamethonium, masseter spasm and later malignant hyperthermia.

A 25-year-old man admitted with severe upper torso trauma displayed masseter muscle spasm after suxamethonium given during resuscitation. Anaesthesia was initially maintained with intravenous agents during transfer and X-ray angiography. However, during surgery to correct a brachial artery injury, malignant hyperthermia was triggered when isoflurane was given, 2.5 h after the suxamethonium. He responded to treatment, including dantrolene administration. Peak serum and urine myoglobin were 12,947 micrograms.l-1 and 54,571 micrograms.l-1, respectively, while maximum serum creatinine kinase was 17,300 IU. The patient made an uneventful recovery and later proved positive for malignant hyperthermia susceptibility on muscle contracture tests.

Adult↗
PubMed1998

Intermittent calcitriol therapy in secondary hyperparathyroidism: a comparison between oral and intraperitoneal administration.

BACKGROUND: Intermittent oral or intravenous doses of calcitriol given two or three times per week are commonly used to treat secondary hyperparathyroidism (secondary HPT). This study was undertaken to compare the biochemical and skeletal responses to thrice weekly intraperitoneal (i.p.) versus oral doses of calcitriol in children with secondary HPT undergoing peritoneal dialysis (CCPD). METHODS: Forty-six patients aged 12.5+/-4.8 years on CCPD for 22+/-25 months were randomly assigned to treatment with oral (p.o.) or i.p. calcitriol for 12 months; 17 subjects given p.o. calcitriol and 16 subjects given i.p. calcitriol completed the study. Bone biopsies were performed at the beginning and at the end of the study, while determinations of serum and total ionized calcium, phosphorus, alkaline phosphatase, parathyroid hormone (PTH) and calcitriol levels were done monthly. RESULTS: Serum total and ionized calcium levels were higher in subjects treated with i.p. calcitriol, P < 0.0001, whereas serum phosphorus levels were higher in those given p.o. calcitriol, P < 0.0001. For the i.p. group, serum PTH levels decreased from pre-treatment values of 648+/-125 pg/ml to a nadir of 169+/-57 pg/ml after nine months. In contrast, serum PTH levels did not change from baseline values of 670+/-97 pg/ml in subjects given p.o. calcitriol, P < 0.0001 by multiple regression analysis. Serum alkaline phosphatase levels were also lower in patients treated with i.p. calcitriol, P < 0.0001, but there was no difference between groups in the average dose of calcitriol given thrice weekly. The skeletal lesions of secondary HPT improved in both groups, 33% of patients developed adynamic bone lesion. CONCLUSION: Differences in the bioavailability of calcitriol and/or in phosphorus metabolism may account for the divergent biochemical response to p.o. and i.p. calcitriol.

Administration, Oral↗
PubMed1998

Bone disease in children and adolescents undergoing successful renal transplantation.

Little is known about the extent and severity of bone disease in children undergoing successful renal transplantation. To address this issue, 47 patients with stable renal function 3.2 +/- 1.7 years after transplantation (Tx) underwent iliac crest bone biopsy. The mean age of patients was 12 +/- 2.0 years; 36 had received cadaveric renal grafts, whereas 11 had undergone living-related Tx. Immunosuppressive drugs included cyclosporine 0.17 +/- 0.4 mg/kg/day, prednisone 7.5 +/- 2.1 mg/kg/day, and either azathioprine 1.6 +/- 0.9 mg/kg/day or mycophenolate mofetil 30 +/- 3 mg/kg/day. In addition to quantitative bone histomorphometry, the bone mineral content (BMC) of the lumbar spine was measured by dual energy X-ray absorptiometry (DXA) in 24/47 patients. Thirty-one transplant recipients had normal bone formation (N-Bfr), 11 had mild hyperparathyroidism (HPT) and 5 had adynamic skeletal lesions (AD). The interval since Tx, duration of dialysis before Tx and cumulative prednisone dose did not differ among groups. Trabecular bone area was highest in subjects with HPT. Unexpectedly, eroded bone perimeter exceeded normal reference values both in patients with AD and in those with N-Bfr; the osteoid area and osteoid perimeter were also elevated in these two groups. Hyperparathyroidism improved or resolved after Tx in all 14 subjects with this skeletal lesion prior to Tx, but one patient developed AD after Tx. Bone histology did not change after Tx in those with N-Bfr during regular dialysis, but bone formation increased after Tx in two of three patients with AD during regular dialysis. Z-scores for height in pre-pubertal patients after Tx were below age-appropriate values in each histologic subgroup, but values did not differ among groups. Z-scores for bone mineral content at the lumbar spine were also less than age-predicted values, -0.67 +/- 1.2. After adjusting for the degree of growth retardation, height-adjusted z-scores for lumbar spine BMC after Tx were above normal in all three histologic groups (0.68 +/- 1.0). The results suggest that reductions in bone mass and post-transplant osteoporosis are not prominent findings in pediatric renal transplant recipients when the influence of growth retardation on bone mass measurements by DXA is carefully considered.

Adolescent↗
PubMed1998

Inhibition of Chlamydia pneumoniae replication in HEp-2 cells by interferon-gamma: role of tryptophan catabolism.

Interferon-gamma (IFN-gamma) induces tryptophan catabolism in HEp-2 cells, possibly via stimulation of host cell indoleamine-2,3-dioxygenase activity, in a dose-dependent (12.5-1600 U/mL) fashion after 24 h, resulting in a 99% conversion to its metabolites at 1600 U/mL. Replication of Chlamydia pneumoniae isolates A-03 and BAL-16 was inhibited in HEp-2 cells following treatment with 50 and 100 U/mL IFN-gamma, respectively; however, addition of excess L-tryptophan (200 microg/mL) to monolayers infected with C. pneumoniae resulted in unrestricted growth of both isolates up to 1600 U/mL IFN-gamma. C. pneumoniae could be recovered from IFN-gamma-treated monolayers, indicating the potential for this bacterium to undergo an altered life cycle, in vitro, analogous to that described in detail for Chlamydia trachomatis. The ability of C. pneumoniae to persist in host tissue despite an immunologic response would be an important attribute in order to cause or exacerbate chronic infections.

Animals↗
PubMed1998

Characterization of a strain of Chlamydia pneumoniae isolated from a coronary atheroma by analysis of the omp1 gene and biological activity in human endothelial cells.

Chlamydia pneumoniae is a respiratory pathogen that has been associated with chronic inflammatory diseases such as asthma and atherosclerosis. Recent isolation of C. pneumoniae from human carotid and coronary atheromas provides additional support for a role of this organism in atherogenesis. We characterized the coronary strain C. pneumoniae A-03 by sequence analysis of the major outer membrane protein gene (omp1). In addition, the in vitro activities of A-03 and three respiratory strains of C. pneumoniae (BAL-16, TW-183, and T-2634) were examined in infected human umbilical vein endothelial cells (HUVEC) by analysis of the production of interleukin-8 (IL-8), monocyte chemotactic protein 1 (MCP-1), and soluble intercellular cell adhesion molecule 1 (sICAM-1). Sequence analysis of omp1 of C. pneumoniae A-03, compared to prototype strains TW-183 and AR-39, revealed five nucleotide changes resulting in nonsynonymous codons. Of interest was a nonconservative amino acid substitution (Ser to Pro) in position 61 of variable segment 1. In vitro, the extent of MCP-1, IL-8, and sICAM-1 production was dependent on the C. pneumoniae strain examined at low multiplicities of infection following 24 h of incubation. Strain A-03 displayed the lowest stimulatory activity in infected HUVEC, while T-2634 induced the highest levels of MCP-1, IL-8, and sICAM-1 among all strains examined. Heat-inactivated C. pneumoniae failed to stimulate production of these proteins by all strains tested. In contrast, only partial inhibition was observed by UV-inactivated organisms. Results from this study demonstrate that unlike prototype respiratory strains of C. pneumoniae, the coronary strain A-03 displays divergence in the omp1 gene. In addition, the stimulation of chemokines and adhesion molecules involved in the recruitment of leukocytes to sites of inflammation by C. pneumoniae may be important in the pathogenesis of diseases associated with this organism, including atherosclerosis.

Amino Acid Sequence↗
PubMed1998

Signal transduction during Legionella pneumophila entry into human monocytes.

Legionella pneumophila causes Legionnaires' disease by replication in alveolar macrophages and monocytes. The bacteria are internalized most efficiently by opsonin-dependent, CR3-mediated phagocytosis. This investigation focused on determining the role of actin polymerization and phosphorylation signals in this uptake mechanism. Uptake inhibition assays and confocal microscopic analysis indicated that entry of L. pneumophila activated tyrosine kinase (TK) and protein kinase C (PKC) and induced actin polymerization at the site of bacterial entry. Upon L. pneumophila entry, six major cellular proteins (75, 71, 59, 56, 53, and 52 kDa) were TK phosphorylated in soluble fractions of monocytes, and three of these proteins (52, 53, and 56 kDa) were consistently found in insoluble (i.e., cytoskeletal) fractions of monocytes as well. Tyrosine phosphorylation was suppressed when cells were pretreated with the kinase inhibitor genistein, tyrphostin, or staurosporine. A similar tyrosine-phosphorylated protein pattern was observed with CR3-mediated entry of avirulent L. pneumophila, Escherichia coli, or zymosan into monocytes. This study has shown that PKC and TK signals which activate actin polymerization during the process of phagocytosis are induced upon L. pneumophila entry. In addition, CR3 receptor-mediated phagocytosis into monocytes may involve tyrosine phosphorylation of similar proteins, regardless of the particle being phagocytosed. Therefore, the tyrosine-induced phosphorylation observed during opsonized L. pneumophila entry is not a virulence-associated event.

Actins↗
PubMed1998

Switch therapy with beta-lactam/beta-lactamase inhibitors in patients with community-acquired pneumonia.

BACKGROUND: Antimicrobial drugs are prescribed inappropriately nearly 50% of the time. To address this problem, a hospital antimicrobial team was formed integrating the talents of infectious disease physicians, pharmacists, microbiologists, infectious control practitioners, and nurses. The primary goal of the team is to provide optimal, cost-effective antimicrobial therapy. OBJECTIVE: To review the principles of streamlining antimicrobial therapy, with an emphasis on antibiotic switch therapy. DISCUSSION: With appropriate guidelines, switch therapy appears to be an important means to provide optimal antimicrobial therapy complementing the many social pressures placed on patients, while positively impacting on the overall cost of treatment. The use of beta-lactam/beta-lactamase inhibitor combinations as the antibiotics for initial intravenous medication to oral combination switch therapy is a viable approach to the treatment of hospitalized patients with community-acquired pneumonia. Preliminary data from our institution were obtained with such a therapeutic approach to assess the clinical efficacy, patient satisfaction with their care, and calculated dollar savings in the overall cost of care. The results of this evaluation strongly support the validity and desirability of such an approach. CONCLUSIONS: The prospective use of a program that incorporates the use of beta-lactam/beta-lactamase inhibitor combinations for intravenous and switch-to-oral drug administration is a cost-effective means of providing optimal antimicrobial therapy for patients with community-acquired pneumonia.

Administration, Oral↗
PubMed1998

[Efficacy and tolerance of the bisoprolol/hydrochlorothiazide combination in arterial hypertension].

PURPOSE: Multicenter, open and non-controlled study to evaluated the efficacy and the tolerability of a low-dose combination of two anti-hypertensive agents: a cardioselective beta-blocker, bisoprolol (2.5 and 5.0 mg) with 6.25 mg of hydrochlorothiazide. METHODS: One hundred and six patients in the stage I and stage II of the systemic hypertension (mild to moderate) were given the bisoprolol/hydrochlorothiazide combination once daily and the diastolic and systolic blood pressures were monitored during the 8-week trial. RESULTS: The bisoprolol/hydrochlorothiazide combination reduced the initial mean values of systolic and diastolic blood pressures, respectively, from the 157.4 mmHg and 98.8 mmHg to 137.3 mmHg and 87.4 mmHg. At the end of the treatment period, 61% of the patients normalized blood pressure values (< 90 mmHg) and 22.9% of them had responded to the treatment, resulting in a total response rate (normalized + responsive) of 83.9% of cases. Adverse events were described only in 18.9% of the patients and dizziness and headache were the most common. There were no clinically significant changes on plasma levels of potassium, uric acid, glucose, or in the lipid profile. CONCLUSION: The combination of low dosages of bisoprolol and hydrochlorothiazide may be considered an effective, well tolerated and rational alternative for the initial treatment of the patients with mild to moderate hypertension.

Adult↗
PubMed1997

Quality of life after kidney transplantation in children.

We assessed the long-term rehabilitation and quality of life after kidney transplantation in 17 recipients of transplants during their childhood who had reached 10 years or more after grafting. We found that all recipients considered themselves to be in good to excellent health, and 59% were completely satisfied with their life. Ninety-four percent of the recipients did not report any interference of their health with their family life. Only one recipient was unemployed, and five recipients have to miss work (n=2) and school (n=3) a few days a year due to their health status. Health seldom or never interfered with social life in 11 recipients, and in 6 of 9 sexually active recipients, their health status was not an obstacle in their sexual relationships. Two recipients expressed concerns about their short stature, and three were concerned with their body appearance. In conclusion, we describe a group of young adult recipients who presented a highly satisfactory rehabilitation and quality of life after their successful transplantation.

Adolescent↗
PubMed1997

Syndrome of inappropriate secretion of antidiuretic hormone in nasopharynx carcinoma.

The syndrome of inappropriate secretion of antidiuretic hormone (ADH) or SIADH has been reported in various disorders. We report a pediatric patient with nasopharynx carcinoma who may have developed a clinical SIADH with severe hyponatremia and generalized seizure during the administration of intravenous hydration. We propose that the inappropriately high plasma level of ADH led to the inability to excrete sufficient amounts of free water during a hyperhydration protocol with a relatively hypotonic fluid, which resulted in acute hyponatremia and central nervous system involvement. To avoid this complication, intravenous hydration before chemotherapy in children with nasopharynx carcinoma should be performed at a slower infusion rate and with a sodium chloride concentration of more than half isotonic.

Child↗