PubMed Health⌕ Search

Biomedical subjects

A A Rodriguez

Publications and source records attributed to A A Rodriguez.

At least 19 recordsLinked to original sources
PubMed2005

Comparison of and investigation into the size effects on the rotational dynamics of two spherical molecules: CCl4 and C60.

13C spin-lattice relaxation measurements were performed on CCl4 and C60, two spherical molecules, to investigate the role of molecular size on reorientational dynamics. Measurements were taken at common temperatures and in a common environment; deuterated chlorobenzene-d5. Our data indicate that both CCl4 and C6) reorient in the small-step diffusion limit. Correlation times for CCl4 were found to be smaller in CBZ than in the neat and much shorter than predicted by viscosity arguments. We have attributed the higher rotational freedom to higher "free volume" or lower solute-solvent contact probability, in CBZ than in the neat. Experimental tau C values for CCl4 and C60 in CBZ were found to be much different than those predicted by hydrodynamics. Pure inertia differences did not explain the disparities in the correlation times. However, a very reasonable explanation for our experimental findings was found by considering the solvent-to-probe molecular volume ratio and its effect on rotational diffusion. We applied four hydrodynamic-based theories to our data and found that the model by Gierer-Wirtz best duplicated our experimental observations. The success of this model suggests that the relative size of solute and solvent molecules, as well as events at the microscopic level, rather than bulk properties, are excellent descriptors of the factors affecting rotational diffusion.

Journal Article↗
PubMed2000

Monoclonal antibody DS6 detects a tumor-associated sialoglycotope expressed on human serous ovarian carcinomas.

A newly developed murine monoclonal antibody, DS6, immunohistochemically reacts with an antigen, CA6, that is expressed by human serous ovarian carcinomas but not by normal ovarian surface epithelium or mesothelium. CA6 has a limited distribution in normal adult tissues and is most characteristically detected in fallopian tube epithelium, inner urothelium and type 2 pneumocytes. Pre-treatment of tissue sections with either periodic acid or neuraminidase from Vibrio cholerae abolishes immunoreactivity with DS6, indicating that CA6 is a neuraminidase-sensitive and periodic acid-sensitive sialic acid glycoconjugate ("sialoglycotope"). SDS-PAGE of OVCAR5 cell lysates has revealed that the CA6 epitope is expressed on an 80 kDa non-disulfide-linked glycoprotein containing N-linked oligosaccharides. Two-dimensional non-equilibrium pH gradient gel electrophoresis indicates an isoelectric point of approximately 6.2 to 6.5. Comparison of the immunohistochemical distribution of CA6 in human serous ovarian adenocarcinomas has revealed similarities to that of CA125; however, distinct differences and some complementarity of antigen expression were revealed by double-label, 2-color immunohistochemical studies. The DS6-detected CA6 antigen appears to be distinct from other well-characterized tumor-associated antigens, including MUC1, CA125 and the histo-blood group-related antigens sLea, sLex and sTn.

Antibodies, Monoclonal↗
PubMed1996

Management of recurrent carotid stenosis: should asymptomatic lesions be treated surgically?

PURPOSE: The purpose of this study was to determine factors that may influence patient selection for surgery in recurrent carotid stenosis (RCS) and to contrast the results of primary and secondary carotid endarterectomy (CENDX) with regard to operative morbidity and stroke prevention. METHODS: Forty-eight patients who underwent CENDX for RCS (RCS-OP group) were compared with a contemporaneous group of 40 patients who on at least one post-CENDX duplex ultrasonography study had a greater than 50% stenosis but did not undergo operation (RCS-NO-OP group). This latter group was drawn from 1053 follow-up duplex studies in 348 patients who underwent primary CENDX between the years 1983 and 1993. Each of these two groups was compared with a metanalysis of six key series derived from the literature. RESULTS: No significant differences were seen in the demographics or the incidence of risk factors between the two groups except for a higher incidence of coronary artery disease (p < 0.03) and peripheral vascular disease (p < 0.001) in the RCS-OP group. The operation-specific stroke rate was 2.1%, and the 30-day mortality was also 2.1%. Symptomatic RCS was the indication in 56% of cases. Important anatomic differences were found between groups. The duplex/arteriographic degree of stenosis was greater than 90% in 75% of the patients in the RCS-OP group, whereas only 10% of the patients in the RCS-NO-OP group had greater than 80% stenosis, most being in the 50% to 80% range. An unexpected finding was the sudden progression to occlusion in 10 (25%) of 40 in the RCS-NO-OP group, with 2 (5%) of 10 of the occlusions presenting as unheralded strokes. Overall, a stroke without an antecedent transient ischemic attack occurred in 3 (7.5%) of 40 of patients in the RCS-NO-OP group, all in patients with greater than 75% stenosis on their last documented scan preceding the stroke. CONCLUSION: Given the relatively low stroke rate with surgery in the RCS-OP group (2.1%) and the higher incidence of unheralded strokes (7.5%) in the RCS-NO-OP group, a more aggressive approach may be warranted in patients with asymptomatic high-grade (> 75%) RCS, a strategy not unlike that adopted for primary CENDX.

Aged↗
PubMed1996

Duplex-derived valve closure times fail to correlate with reflux flow volumes in patients with chronic venous insufficiency.

The best way to quantitate venous reflux is still a matter of debate. Duplex-derived valve closure time (VCTs) have been used recently because they can be measured easily. We examined the relationships between VCT and duplex-obtained quantitation of venous volume and between VCT and air plethysmography (APG). Sixty-nine legs in 45 patients with varying clinical degrees of chronic venous insufficiency were studied by duplex scan and APG. VCTs were compared with duplex-derived flow calculations and with APG-derived venous filling index and residual volume fraction. The patient's mean age was 47.5 +/- 13.9 years; the mean duration of their symptoms was 13 +/- 4 years. Twenty percent had a history of deep venous thrombosis, and 29% had undergone venous surgery. No correlation was found between VCT and flow volume or between VCT and flow at peak reflux at any of the anatomic locations studied: saphenofemoral junction, greater saphenous vein, lesser saphenous vein, superficial femoral vein, profunda femoris vein, and popliteal vein. Likewise, no correlation was found between total VCT and APG-derived venous filling index or between total flow volumes and APG-derived residual volume fraction. Total VCT and total flow volumes did, however, have a moderate correlation (r = 0.65; p = 0.0003). Duplex-derived VCTs, although extremely useful in determining the presence of reflux, do not correlate with the magnitude of reflux, and should not be used to quantitate the degree of reflux.

Air↗
PubMed1995

Comparison of skeletal muscle laser Doppler flowmetry to changes in central hemodynamics in detecting the physiological response to moderate hemorrhage.

Previous studies have demonstrated that laser Doppler (LD) flowmetry is a useful technique for following changes in blood flow in a tissue bed, but the potential role of LD flowmetry in management of the critically ill patient is unclear. This study sought to establish the sensitivity of LD flowmetry compared to changes in centrally measured hemodynamic parameters in response to a mild hemorrhagic episode. In order to establish the correlation between LD flow and actual blood flow, livers from Sprague-Dawley rats were isolated and perfused via the portal vein with citrate anti-coagulated rat blood. Changes in LD flow were recorded while changing blood flow via the perfusion pump. There was a strong correlation between pump flow and LD flow (for N = 5 livers, r > 0.9; P < 0.05). This relationship was stable at hematocrits > 20. The second part of this study tested the sensitivity of LD flowmetry in anesthesized baboons. An LD probe was placed on the surface of the gracilis muscle of the adult male baboons. LD flow and hemodynamic parameters were measured following two episodes of bleeding and reinfusing 250 cc of blood. During the first bleed there were significant changes in heart rate (97 + 8 to 159 + 12), mean arterial pressure (125 + 6 to 105 + 9), and LD flow (20.6 + 4.6 to 11.9 + 3.6); these parameters returned to normal after reinfusion of blood. During the second bleed, the only parameters that showed significant changes were heart rate (118 + 5 to 135 + 12) and LD flow (17.5 + 8 to 10.7 + 3.4).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Adenomyosis as seen on blood flow and blood pool imaging during bone scintigraphy.

A 42-year-old woman presented with intermittent low back and left lower extremity pain. The blood flow and blood pool images of bone scintigraphy showed a large focus of increased activity in the right lower abdomen. Computed tomography showed an enlarged uterus displaced to the right side of the pelvis. At surgery, the uterus was found to be involved with adenomyosis. Three-phase bone scintigraphy consisting of blood flow and blood pool images over the anterior pelvis may be a valuable diagnostic aid in the evaluation of lower back or pelvic pain of a woman.

Adult↗
PubMed1993

Reliability determination of F mean response latency.

Two hundred consecutive ulnar F wave latencies were evaluated in 30 healthy controls (C) and in 9 patients with mild neuropathy (N). The primary study objective was to determine the F wave sample size required to obtain a reliable F mean latency. A secondary objective was to explore the diagnostic utility of three F wave parameters: the minimal F wave latency (Fmin), the average F wave latency (Fmean), and the minimal-maximal F wave latency difference (Frange). For the control group, the Fmean reliability estimates as measured by intraclass correlation coefficients were 0.87, 0.97, and 0.99 with 1, 5, and 10 responses, respectively; for the N group, the corresponding values were 0.73, 0.93, and 0.96. Fmean was abnormal in 89% of the subjects with mild neuropathy whereas Frange and Fmin were abnormal in 67% and 33%, respectively. The study suggests (1) a reliable F mean latency can be obtained by averaging ten F responses; and (2) Fmean and Frange offers promise in increasing the diagnostic utility of the F response in identifying mild neuropathies.

Adult↗
PubMed1992

A prospective, randomized trial of Unna's boot versus Duoderm CGF hydroactive dressing plus compression in the management of venous leg ulcers.

Leg ulcers caused by chronic venous insufficiency plague an estimated 500,000 Americans, but there have been few improvements in conservative treatment in this century, and Unna's boot continues to be a mainstay of therapy. A recent report suggests that Duoderm CGF dressing provides greater patient comfort and enhanced compliance, but Duoderm alone (without compression) resulted in slower healing compared with Unna's boot. We enrolled 30 patients (30 ulcers) in a clinical trial to compare Duoderm CGF plus compression (Coban wrap) to Unna's boot. No significant difference was observed between the two groups with respect to age, sex, initial ulcer area, ulcer duration, or extent of venous insufficiency by duplex scan. Eight of 16 ulcers (50%) in the Duoderm group healed completely versus 6 of 14 ulcers (43%) in the Unna's boot group (p = 0.18). Healing rates (square centimeters per week) correlated significantly with initial ulcer area and initial ulcer perimeter for both groups but best correlated with initial ulcer perimeter (r = 0.88 with Duoderm, p less than 0.0001; r = 0.80 with Unna's boot, p less than 0.002). After adjusting for differences in initial ulcer perimeter, healing rates were significantly faster for patients on Duoderm than patients on Unna's boot during the first 4 weeks of therapy (0.384 +/- 0.059 cm2/wk/cm perimeter for Duoderm versus 0.135 +/- 0.043 cm2/wk/cm perimeter for Unna's boot; p = 0.002). At 12 weeks patients on Duoderm again appeared to heal faster than those on Unna's boot, although the result did not reach statistical significance (0.049 +/- 0.007 cm2/wk/cm perimeter for Duoderm versus 0.020 +/- 0.017 for Unna's boot, p = 0.11).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1991

Patterns of venous insufficiency in patients with varicose veins.

The nature and distribution of venous disease surrounding the development of varicose veins and its treatment is controversial. Using duplex ultrasonography, we evaluated 54 lower extremities in 32 patients with varicose veins who were symptomatic and had obvious varicose veins by clinical examination. Twenty-eight percent had greater saphenous trunk incompetence, 2% had lesser saphenous trunk incompetence, and 96% had branch disease. Deep valvular incompetence was seen in 41%, saphenofemoral junction incompetence in 46%, and incompetence of one or more perforators in 46% of the extremities. Thirty-three percent demonstrated no evidence of associated saphenofemoral junction, deep vein, or perforating vein incompetence, while 20% had concurrent saphenofemoral junction, deep vein, and perforating vein incompetence. These data support the heterogeneity of venous disease seen in patients with varicose veins and suggest that surgical therapy be directed to a patient's specific pattern of incompetence rather than routine saphenofemoral junction ligation or stripping of the greater saphenous trunk.

Adult↗
PubMed1991

Liver viability after ischemia-reperfusion.

Lack of a reproducible model to quantitatively assess hepatocellular injury following ischemia has made it difficult to assess new strategies for minimizing hepatic injury. We studied the progression of hepatocellular injury after ischemia and ischemia with reperfusion in rats. Irreversible injury was quantitated using a triphenyltetrazolium chloride assay that was shown to correlate with ultrastructural changes. Adenosine triphosphate decreased to 36% of basal values after 30 minutes, but returned to normal with reperfusion with no decrease in viability. In contrast, viability fell by 30% after 60 minutes of ischemia, and by 64% when 60 minutes of ischemia was followed by reperfusion. We conclude that reperfusion of ischemic liver increases the degree of irreversible damage. The model employed here seems to be useful for studying ischemic and reperfusion injury in the liver.

Adenine Nucleotides↗
PubMed1991

Correlation of motor units with strength and spectral characteristics in polio survivors and controls.

The purpose of this study was to determine whether quantitative motor unit analysis in postpolio individuals correlates with muscle strength, endurance, work capacity, or power spectral characteristics of surface EMG and to determine whether power spectrum differentiates postpolio from control subjects. This study was designed to compare these variables in 34 symptomatic postpolio, 16 asymptomatic postpolio, and 41 control subjects. Quantitative motor unit analysis of the quadriceps femoris muscle was performed using a concentric needle electrode. Isometric knee extension peak torque, endurance (time to exhaustion) at 40% of maximal torque, work capacity (tension time index), and recovery of force through 10 minutes post-exhaustion were determined. Median frequency of the surface power spectrum was determined during the above testing. Power spectrum histograms were compared at the onset and termination of endurance exercise. Motor unit action potential variables did not correlate with isometric peak torque, tension time index, endurance time, recovery of strength, or with median frequency. Surface power spectrum did not differentiate postpolio from control subjects.

Action Potentials↗
PubMed1991

Serendipitous finding of transitional cell carcinoma of the kidney on bone and gallium imaging.

A 50-year-old woman presented with low back pain. Bone scintigraphy showed a focus of increased activity in the upper pole of the left kidney. Subsequent Ga-67 citrate scintigraphy demonstrated this same abnormal focus as a region of increased activity. Ultrasonography showed a renal mass in the upper pole of the left kidney. At surgery a transitional cell carcinoma of the upper pole of the left kidney was found.

Bone and Bones↗
PubMed1991

Distribution of valvular incompetence in patients with venous stasis ulceration.

Valvular incompetence associated with venous ulceration can occur in the superficial, deep, or perforating systems. Duplex imaging was used to evaluate 95 extremities (78 patients) with current venous ulceration to determine the location of incompetence in each extremity. In addition, in 91 of the 95 extremities the area of the venous ulcer was evaluated for the presence of perforating veins or any other superficial veins or both conditions. Sixty-three (66.3%) of the 95 extremities had multisystem incompetence (superficial and perforating plus superficial and deep plus perforating and deep plus superficial and perforating and deep), whereas single system incompetence (superficial plus perforating plus deep) was seen in only 26 (27.3%). Isolated deep incompetence was identified in only two extremities (2.1%). Furthermore, 45% (41/91) of the ulcers had no duplex evidence of any venous abnormality in the ulcer bed. These data show that the site of valvular incompetence occurred in multiple locations, that isolated valvular incompetence of the deep venous system was uncommon, and that perforating veins were not always in the ulcer bed itself. Because standard venous surgery has traditionally been directed toward only one system, this may provide one explanation for ulcer recurrence. Therefore complete venous evaluation with duplex imaging allowing for surgical intervention directed specifically to the sites of involvement in each system is recommended.

Female↗