Biomedical subjects
Publications and source records attributed to M J Molina.
We present experimental results obtained with a differential scanning calorimeter (DSC) that indicate the small ice particles in low-temperature cirrus clouds are not completely solid but rather coated with an unfrozen H2SO4/H2O overlayer. Our results provide a new look on the formation, development, and microphysical properties of low-temperature cirrus clouds.
The aim of this study was to determine the association between lupus autoantibodies and the clinical manifestations and outcome in a cohort of Puerto Ricans patients with systemic lupus erythematosus (SLE). All patients fulfilled the American College of Rheumatology classification criteria for SLE. Demographic parameters, clinical manifestations over time and damage accrual were obtained at the last study visit. Disease damage was assessed with the Systemic Lupus International Collaborating Clinics Damage Index (SDI). ANA, ANA pattern, and anti-dsDNA, anti-Smith, anti-Ro (SSA), anti-La (SSB) and anti-snRNP antibodies were measured at the time of SLE diagnosis. Chi-square test, Fisher exact test, ANOVA, logistic regression and general lineal model analyses were used to evaluate these associations. Ninety-six percent of patients were females. The cohort had a mean age of 40.2 +/- 12.0 years and mean disease duration of 9.6 +/- 7.0 years. Patients with elevated anti-dsDNA antibodies were more likely to have vasculitis, pericardial effusion, renal involvement, anaemia, leukopenia, lymphopenia and thrombocytopenia. Anti-Smith antibodies were positively associated with skin ulcerations, elevated liver enzymes, renal involvement and thrombocytopenia. Anti-Ro antibodies were related with the presence of discoid lupus, serositis, pneumonitis, elevated liver enzymes, hemolytic anaemia, leukopenia and lymphopenia. No positive associations were found for anti-snRNP or anti-La antibodies. The presence of anti-dsDNA, anti-Smith and anti-Ro antibodies was associated with higher SDI scores. In conclusion, anti-dsDNA, anti-Smith and anti-Ro antibodies are associated with several clinical manifestations and more damage accrual in Puerto Ricans with SLE. These findings provide valuable clinical and prognostic information for this ethnic population.
Relative rate techniques were used to measure k(OH + HFE-7500) = (2.6+/-0.6) x 10(-14), k(Cl + HFE-7500) = (2.3+/-0.7) x 10(-12), k[Cl + n-C3F7CF(OC(O)H)CF(CF3)2] = (9.7+/-1.4) x 10(-15), and k[Cl + n-C3F7CF(OC(O)CH3)CF(CF3)2] < 6 x 10(-17) cm3 molecule(-1) s(-1) at 295 K [HFE-7500 = n-C3F7-CF(OC2H5)CF(CF3)2]. From the value of k(OH + HFE-7500) an estimate of 2.2 years for the atmospheric lifetime of HFE-7500 is obtained. Two competing loss mechanisms for n-C3F7-CF(OCHO.CH3)CF(CF3)2 radicals were identified in 700 Torr of N2/O2 diluent at 295 K; reaction with O2 and decomposition via C-C bond scission with kO2/k(decomp) = 0.013+/-0.006 Torr(-1). The Cl atom initiated oxidation of HFE-7500 in N2/O2 diluent gives n-C3F7CF(OC(O)CH3)CF(CF3)2 as the major product and n-C3F7CF(OC(O)H)CF(CF3)2 as a minor product. The atmospheric oxidation of HFE-7500 gives n-C3F7-CF(OC(O)CH3)CF(CF3)2 and n-C3F7CF(OC(O)H)CF(CF3)2 as oxidation products. The results are discussed with respect to the atmospheric chemistry and environmental impact of HFE-7500.
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The purpose of this study was to compare the shear bond strength of a resin composite to air abraded and not air abraded enamel and dentin surfaces, and to evaluate the need for acid conditioning before the application of a single component adhesive. Enamel (E) and dentin (D) flat surfaces were obtained from a pool of recently extracted human teeth (30 incisors and 30 molars) and prepared with different treatments with and without the application of air abrasion (AA) and phosphoric acid (PA). Composite samples were bonded to the surfaces and stored in distilled water at 37 degrees C. After 24 hours, shear bond strength tests were carried out with an Instron machine and the results were subjected to statistical analysis. Maximum bond strength was obtained in the E + AA + PA group (34.74 MPa--2.70), followed by: E + PA (31.26 MPa--1.87); D + PA (24.09-1.72); D + AA + PA (20.61 MPa--1.79); D + AA (8.96 MPa--0.82) and E + AA (7.17 MPa--1.75). The results were significantly lower in those groups that were not acid conditioned (P < 0.01). The bond strength of composite to enamel was slightly increased as a result of the combination of AA with PA. However, the opposite effect was observed on dentin surfaces. Acid etching is a necessary clinical step even on air abraded surfaces.
The inhibitory effect of nitric oxide (NO) on carotid chemosensory responses to hypoxia has been attributed in part to an antidromic inhibition of chemoreceptor cells activity. However, NO may also modulate the activity of the primary sensory neurons because NO is produced in the soma of these neurons located in the petrosal ganglion. Since a population of petrosal neurons is selectively activated by acetylcholine (ACh), we studied the effects of NO-donor, sodium nitroprusside (SNP), and the NO-synthase inhibitor, Nomega-nitro-l-arginine methyl ester (l-NAME), on the responses evoked in the carotid sinus nerve (CSN) by ACh applied to the petrosal ganglion in vitro. ACh (1 microgram-1 mg) increased the frequency of action potentials recorded from the CSN in a dose-dependent manner. SNP (10-50 microM) reduced the sensibility and amplitude of the CSN response to ACh, although the maximal response appears less affected. The withdrawal of SNP from the superfusion medium increased the sensibility of the responses to ACh. l-NAME (1-2 mM) slightly increased the sensibility of the ACh-induced responses, effect that persisted after l-NAME withdrawal. These results suggest that NO may play a role as modulator in this autonomic primary sensory ganglion.
BACKGROUND: Follow-up study of patients with surgical repair of aneurysmal subarachnoidal hemorrhage (SAH), looking for clinical outcome predictors. PATIENTS AND METHODS: Sixty two patients consecutively admitted to a teaching hospital, from January 1992 to December 1995 were included in the study. We studied preoperative, intraoperative and postoperative features looking for their relationship with the outcome. The ultimate outcome was evaluated by means of Glasgow Outcome Scale on discharge and 6 months later. RESULTS: Smoking (p = 0.0001) and arterial hypertension (AHT) (p = 0.0186) were more frequent in these patients than in general population, but without relationship to the outcome as with the age of the clinical status on admission. The greatest statistical relationship was found between the level of consciousness on postoperative awakening (measured by the Hunt and Hess scale), and the outcome (p = 2.53 x 10(-8). From our results we made an algorithm that correctly assigned 92% of studied patients to their outcome. CONCLUSIONS: All patients admitted on with aneurysm SAH deserve intensive care treatment besides their clinical grade. The level of consciousness on postoperative awakening was a good outcome predictor.
PURPOSE: Epidural anesthesia is believed to benefit colorectal anastomotic blood flow because of the sympathetic blockade it produces. Our purpose is to measure with tonometry the effect of epidural anesthesia on colorectal anastomotic oxygenation. PATIENTS AND METHODS: Fifteen patients operated on for rectal cancer (radical anterior resection) were monitored postoperatively using tonometers placed in the stomach (celiac trunk), transverse colon (superior mesenteric artery), and the anastomotic area during the operation. An epidural catheter was placed at L1-2, and on the first postoperative day, 8 ml of bupivacaine (0.25 percent) was administered. The anesthetic effect extended up to T-4. Intramucosal pH (pHi) at the three locations was measured before, during, and after the epidural blockade. RESULTS: Gastric and transverse colon pHi increased during the epidural blockade from 7.35 +/- 0.01 to 7.41 +/- 0.01 and from 7.34 +/- 0.02 to 7.40 +/- 0.02, respectively. The anastomotic pHi decreased from 7.3 +/- 0.02 to 7.24 +/- 0.03 under the epidural and increased up to 7.34 +/- 0.02 after withdrawal of the effect on the following day. All pHi variations were statistically significant (P < 0.05, paired Student's t-test and Wilcoxon's test), because it was the comparison between gastric and transverse colon pHi with the anastomotic pHi during the epidural (P < 0.05, one-way analysis of variance and Kruskal-Wallis tests). None of the patients developed anastomotic or other complications. CONCLUSIONS: Epidural anesthesia with bupivacaine causes a significant decrease in the oxygenation-perfusion state of colorectal anastomosis in comparison with the increase in other areas of the digestive tract. Further studies need to be done to see if other epidural anesthetic-analgesic protocols also worsen colorectal anastomotic blood flow.
A patient with myotonic dystrophy and associated primary hyperthyroidism and hyperparathyroidism is described; this association has not been reported previously, to the authors' knowledge. The patient also suffered from hypergonadotropic hypogonadism and hyperinsulinism with insulin resistance. The etiology of hyperthyroidism and hyperparathyroidism is not clear. At surgery, a parathyroid adenoma was extirpated, and a subtotal thyroidectomy was performed. Postoperative course was unremarkable, with consistently normal serum calcium levels but persistently elevated serum parathyroid hormone concentrations. The possibility that the patient had a residual hyperparathyroidism could not be eliminated. Thyroid function was normal. After surgery, the patient reported subjective improvement in his muscle strength. The authors conclude that both diseases-- hyperthyroidism and hyperparathyroidism--exert a negative effect on the myotonic dystrophy and that an early recognition of these two diseases is crucial for the favorable evolution of the patient.
Lactate determinations did not contribute to the quantification of the systemic and regional tissue oxygenation during OLT. Venous stasis was not an important factor in the tissue imbalance between oxygen supply and oxygen demand.
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A deterioration in cognitive functions is characteristic of the ageing process and is one of the principle causes for disability in old age. It is possible that some of the neuropsychiatric alterations associated with old age may be due to certain subclinical vitamin deficiencies and, as such, may be corrected in some cases with adequate nutrition. This article presents a broad review of the various research efforts published on the subject.
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