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Biomedical subjects

S Rodriguez

Publications and source records attributed to S Rodriguez.

At least 91 records · Page 5Linked to original sources
PubMed1992

Lack of relationship between the true airway pressure and the pressure displayed with an infant ventilator.

OBJECTIVE: To establish if the pressure indicated in the manometer of an infant ventilator (IV 100B, Sechrist, Anaheim, CA) reflects the true pressure delivered to the proximal airway during mechanical ventilation in the neonatal ICU. DESIGN: With approval of our Institutional Research Board, data were collected prospectively. Peak inspiratory pressure and end-expiratory pressure were measured at the "Y" piece of the breathing tubing. Pressure readings from the conventional ventilator's manometer were compared with simultaneously obtained measurements using an electronic monitor. SETTING: This study was conducted in a 45-bed neonatal ICU, admitting 700 to 750 newborns per year. PATIENTS: Twelve neonates who required mechanical ventilation were included in the study. INTERVENTIONS: Specific interventions were not made by study design. Measurements routinely obtained were compared. MEASUREMENTS AND MAIN RESULTS: Two hundred seventy-five simultaneous measurements of peak inspiratory pressure and positive end-expiratory pressure were compared. Peak inspiratory pressure values were higher with the electronic monitor in 273 (99%) of 275 measurements and the mean of the differences between the electronic monitor and ventilator's manometer was statistically significant (p less than .001). For positive end-expiratory pressure measurements, values indicated by the electronic monitor were lower in 152 (55%) of 275 determinations, equal in 65 (23%), and higher in 58 (21%) determinations. Percent variations between methods ranged from 0% to 140% for peak inspiratory pressures and from 0% to 500% for positive end-expiratory pressure. CONCLUSIONS: These data demonstrate that it is impossible to know the true pressure delivered to the proximal airway of a neonate during mechanical ventilation by observing the ventilator pressure manometer. The manometer readings consistently underestimate the true peak inspiratory pressure values and are very unpredictable regarding positive end-expiratory pressure values. These findings support the use of other methods to monitor the proximal airway pressure besides the ventilator's manometer in the neonatal ICU. Furthermore, mean airway pressure should not be calculated from the pressure readings obtained from the tested ventilator's manometer.

Airway Resistance↗
PubMed1992

Fibrinogen Lima: a homozygous dysfibrinogen with an A alpha-arginine-141 to serine substitution associated with extra N-glycosylation at A alpha-asparagine-139. Impaired fibrin gel formation but normal fibrin-facilitated plasminogen activation catalyzed by tissue-type plasminogen activator.

An A alpha-arginine-141 to serine substitution has been identified in a homozygous dysfibrinogen, fibrinogen Lima, associated with impaired fibrin polymerization. The point mutation created an asparagine-X-serine-type glycosylation sequence, and indeed, extra, mainly disialylated biantennary oligosaccharides have been isolated from A alpha asparagine-139 of the patient's fibrinogen. This type of glycosylation sequence is unique for human fibrinogen, because the sequences shown for normal and abnormal fibrinogens are all asparagine-X-threonine types. The terminal sialic acids of the extra oligosaccharides seem to have largely contributed to the impaired fibrin gel formation, as evidenced by its correction to a near normal level by desialylation. Nevertheless, the polymerizing fibrin facilitated tissue-type plasminogen activator-catalyzed plasmin formation in a normal fashion, indicating that the initial two-stranded fibrin protofibrils had been constructed normally. Thus the impaired fibrin gel formation could be attributed to the delay in their subsequent lateral association, most probably because of the repulsive forces generated by the negative electric charge of the extra sialic acids. The substitution of a basic residue arginine to a noncharged residue serine may also have contributed to the impaired function in a similar manner or by steric hindrance in association with bulky extra oligosaccharide chains.

Amino Acids↗
PubMed1991

Spectrum of Aeromonas and Plesiomonas infections in patients with cancer and AIDS.

The spectrum of infection with Aeromonas and Plesiomonas included gastroenteritis, bacteremia, biliary tract infection, perirectal infection, and disseminated disease. Most patients (86%) with bacteremia were neutropenic (less than 500 PMN/mm3). Colonization of stools and sputum also occurred. Therapy with aminoglycosides, beta-lactams, trimethoprim/sulfamethoxazole, and the newer quinolones was effective in patients with AIDS and cancer.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Clostridial bacteremia in cancer patients. A 12-year experience.

Over 12 years, 136 episodes of bacteremia caused by clostridial species were documented. Eighty-three were monomicrobial, and 53 were polymicrobial. Gastrointestinal, genitourinary carcinomas, and acute leukemia were the most common underlying malignancies. Septic shock occurred in 29% of monomicrobial bacteremias and 45% of polymicrobial bacteremias and was associated with a high mortality rate. Acute hemolysis, gas gangrene, and diffuse spreading cellulitis occurred infrequently but were associated with a 100% fatality rate. Many infections caused by Clostridium perfringens and C. septicum were associated with abdominal disease. The most commonly isolated organism was C. perfringens, followed by C. septicum and C. sporogenes. Overall survival was 58%, but it was 66% for monomicrobial episodes and 45% for polymicrobial infections. All of the patients with bacteremia due to an aerobic gram-negative bacillus in addition to the clostridial species died of their infection. The most effective antibiotics were clindamycin, penicillin, metronidazole, and moxalactam. Surgical drainage of abscesses was an important component of therapy.

Adolescent↗
PubMed1990

Evidence that protein kinase M does not maintain long-term potentiation.

We have shown that the induction but not maintenance of long-term potentiation (LTP) in the Schaffer collateral-CA1 synaptic zone of the rat hippocampus is blocked by the extracellular application of the protein kinase inhibitor staurosporine. This compound was also found to block the induction of LTP in the perforant path-granule cell synaptic zone of the intact hippocampus. We have determined that staurosporine is membrane-permeable and can be detected inside cells by fluorescence microscopy. When cultured fetal hippocampal neurons were treated with staurosporine, fluorescence was observed throughout the cytoplasm and in neurites. Other cell types gave similar results. It has been proposed that constitutively active cytosolic protein kinase M or other protein kinases maintain long-term potentiation. Since staurosporine has access to the cytosol and inhibits protein kinase M in vitro, our results suggest that this enzyme is not responsible for the maintenance of LTP. This conclusion may extend to other protein kinases as well, since staurosporine has been shown to inhibit a variety of these enzymes.

Alkaloids↗
PubMed1990

Fibrinogen Lima. A new dysfibrinogenaemia with a high-molecular-weight alpha-chain and effective polymerization.

A patient with transient microhaematuria was studied. Coagulation tests revealed prolonged thrombin and reptilase times concomitant with abnormal fibrin polymerization rate (also abnormal in both parents). In the patient and her patients, the abnormal fibrin polymerization rate was only slightly corrected by addition of calcium ions. The alpha-chain had a molecular weight higher than normal and there was deficient formation of alpha-polymers. The molecule showed a more anodal migration than the control. The abnormality described has been classified as Fibrinogen Lima.

Afibrinogenemia↗
PubMed1990

A multicenter clinical trial of oral ribavirin in HIV-infected patients with lymphadenopathy. The Ribavirin-LAS Collaborative Group.

A double-blind, randomized, placebo-controlled trial comparing two daily doses of oral ribavirin and placebo was conducted at four medical centers. One hundred sixty-four adult men with lymphadenopathy were enrolled over a 2-month period and randomized to receive ribavirin 800 mg (53 subjects), ribavirin 600 mg (55 subjects), or placebo (56 subjects). Active treatment was administered for 24 weeks followed by a 4-week washout period. Nine subjects receiving placebo, four receiving ribavirin 600 mg, and none in the 800 mg group developed AIDS during the 24 weeks of active treatment. One patient randomized to the 800 mg group had Kaposi's sarcoma at study entry and was included in the intent-to-treat analysis. An overall significant difference in progression to AIDS was observed among the three treatment groups (p = 0.028) with patients randomized to receive 800 mg having a significantly longer time to AIDS than placebo patients (p = 0.012; relative risk, 9.0; 95% confidence interval, 1.1 to 70.8). There was no significant difference between the 600 mg and placebo groups (p = 0.15; relative risk, 2.3; 95% confidence interval, 0.7 to 7.6). Baseline CD4 cell count and hematocrit made independent contributions and formed a multivariate prognostic set for these progression data. The significant treatment superiority of 800 mg compared to placebo remained after adjustment for these factors (p = 0.019). After deletion of patients with major protocol violations at entry, the difference between the 800 mg and placebo treatment remained significant (p = 0.021).(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1990

Bacterial and fungal infections in patients with the acquired immunodeficiency syndrome.

Over a 14-month period, 136 episodes of bacterial and 26 episodes of fungal infection were identified from the microbiology records of 444 patients with acquired immunodeficiency syndrome (AIDS). The respective rates for infection were 31 of 100 admissions (bacterial) and 5 of 100 admissions (fungal). Contributory factors appeared to be therapy with antineoplastic agents, ganciclovir and zidovudine, resulting in neutropenia, corticosteroid therapy, and increased use of central venous catheters. Bacteria isolated most often were Staphylococcus spp., the Enterobacteriaceae, and Pseudomonas aeruginosa. Aspergillus spp. and Candida spp. were the common fungal pathogens. However, several unusual fungal organisms seem to be emerging as important pathogens and can cause disseminated infection. Appropriate and prompt antimicrobial therapy resulted in the resolution of most bacterial infections. Disseminated fungal infections were difficult to treat and responded less often.

Acquired Immunodeficiency Syndrome↗