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Biomedical subjects

M A Gomez

Publications and source records attributed to M A Gomez.

At least 19 recordsLinked to original sources
PubMed2006

Correlation between the radiologic and histologic size of hepatocellular carcinoma in patients eligible for liver transplantation.

Hepatocellular carcinoma is the most prevalent primary hepatic tumor. Early diagnosis and staging is of paramount importance to obtain favorable survivals. So far, there is no general agreement on the most appropriate imaging technique to detect the tumor for correlation between pretransplant radiologic and pathologic size of the tumor, which remains inadequate. With greater clinical experience and increasing accuracy of imaging methods, magnetic resonance (MR) appears to be the most accurate method, yielding a correlation in 67% of cases.

Carcinoma, Hepatocellular↗
PubMed2005

[Assessment of a matrix-based quantitative ultrasound imaging device (Beam scanner): reproducibility].

PURPOSE: A new matrix-based quantitative ultrasound (QUS) device was developed for the assessment of two parameters: BUA (Broadband Ultrasound Attenuation) and SOS (Speed Of Sound). This device, called Beam scanner, is a contact imaging device designed to evaluate the calcaneus. The aim of this preliminary study was to evaluate the reproducibility of results in a sample of patient with heterogeneous age distribution. MATERIALS AND METHODS: Seventy-six subjects were included: 18 healthy young males, 18 healthy young women and 40 women aged over 50 years old, including 19 osteoporotic patients according to WHO criteria. Five measurements were made for each patient after foot repositioning. Short-term precision was estimated using the coefficient of variation (CV), standardized CV (SCV) and intra-class correlation coefficient (ICC). RESULTS: SCV varied with the group of subjects between 2.0 and 4.3% for BUA, and between 3.1 and 4.5% for SOS. Mean values of BUA and SOS were statistically lower for osteoporotic women compared with healthy young women or healthy young males (p<0.001). For BUA, only SCV and ICC were better for women aged over 50 years old but without statistical difference. CONCLUSION: This study shows that the heterogeneity of the studied sample population is not a significant factor when assessing precision. This new device has a precision similar to others QUS devices.

Absorptiometry, Photon↗
PubMed2004

2D arrays device for calcaneus bone transmission: an alternative technological solution using crossed beam forming.

In the context of manned space flight with the European Space Agency, a quantitative ultrasound device for transmission imaging through the calcaneus bone has been developed. It includes two matrix transducers of 576 elements each in order to electronically perform the scanning and the focusing of the 500 kHz ultrasonic beam. This device called the BEAM scanner, provides two parametric images of attenuation (BUA, broadband ultrasonic attenuation) and velocity (SOS, speed of sound) of the investigated skeletal site. The cost and complexity of such a device has motivated the study of an alternative solution, less demanding in terms of technology, based on a crossed beam former [H. Ermert et al., A new concept for a real-time ultrasound transmission camera, in: IEEE Ultrasonics Symposium Proceedings, 2000, pp. 1611-1614]. It consists in forming two perpendicular cylindrically focused planes, one in emission, one in reception, instead of two spherically focused apertures. The crossing line of the two planes replaces the focused beam. The 2D beam forming technological challenge is moved to a 1D simpler and cheaper architecture. In this work the two solutions have been compared for in vivo measurements. Data sets have been acquired using all spatial combinations of emission and reception single elements of the matrix. Then signals have been processed using either the cylindrical or the spherical focussing mode. For cylindrical focussing, the increased level of the side lobes caused severe artefacts. Several apodization techniques have been implemented to reduce these artefacts, resulting in encouraging results. After a brief description of this new ultrasonic method for bone quantitative assessment, several reconstructed images using both processing schemes are presented. Corresponding statistical results obtained in 29 subjects are also provided.

Algorithms↗
PubMed2003

[Primary epiploic appendicitis: an etiology of acute abdomen revealed by CT scan].

Primary epiploic appendicitis are considered to be a rare cause of acute abdomen. We reported 2 cases in which computed tomography CT suggested the diagnosis. Primary epiploic appendicitis shows characteristic CT findings that allow the diagnosis and follow-up. This entity resolves spontaneously and CT helps in avoiding unnecessary surgery.

Abdomen, Acute↗
PubMed2003

[Characterization of adrenal incidentaloma discovered with tomography. General review].

The detection of an incidentaloma at abdominal Computed Tomography (CT), except CT features that permit a specific diagnosis (hemorrhage, myelolipoma or cyst), become a problem to differentiate adenomas from "non adenomas" (primary or secondary malignancy) incidentalomas. A density of ten Hounsfield units or less with a nonenhanced CT is a feature of benign incidentaloma (essentially lipid-rich adrenal adenomas). There are two limitations of this characterization: incidentalomas initially detected at enhanced CT and lipid-poor adrenal adenomas. The relative enhancement washout on enhanced CT, by using a threshold of 50% washout, permit then to characterized as adenomas or "non adenomas" incidentalomas on a 10-minute-delayed enhanced CT. Limitations of this characterization are only for benign pheochromocytomas and atypical adrenal cortical carcinomas.

Adrenal Gland Neoplasms↗
PubMed2003

Differences between patients with non-Hodgkin's lymphomas in a cohort of HIV/AIDS patients in Puerto Rico.

The close association between AIDS and non-Hodgkin's lymphoma (NHL) is well known. Few studies are available that evaluate the profile of NHL in a cohort of HIV-infected patients who reside in Puerto Rico. The present study was performed in a cohort of 2,843 HIV-infected patients followed in the Retrovirus Research Center at Bayamón, Puerto Rico, evaluated between January 1992 until December 2000. NHL prevalence was determined and differences between AIDS defining and non-AIDS defining NHL were evaluated with the Fisher and ANOVA test. NHL prevalence was 0.9%. Nine (33%) were AIDS-defining (AIDS-d) NHL and 18 (67%) were non-AIDS-d NHL. Both groups were similar in gender distribution and mean diagnosis age. The median CD4+ T cell count at diagnosis was below 150/mm3 in both groups. Injecting drug use was higher in AIDS-d NHL patients and Homo-Bisexual contact was higher in non-AIDS-d NHL patients. Death rate in the first year after the NHL was 67% in the AIDS-d group and 56% in the non-AIDS-d group. AIDS-d NHL incidence decreased after the implementation of combined antiretroviral therapy in the cohort, a finding not seen in the non-AIDS-d NHL. In summary the study detected low NHL prevalence, with high degree of immunological damage at the time of the lymphoma diagnosis. Conversely dissimilar response to the antiretroviral therapies was also perceived in the incidence of the two NHL groups.

Adult↗
PubMed2003

Recurrent pneumonia mortality risk in a HIV/AIDS Puerto Rican cohort.

Recurrent pneumonia (RP) within 12 months is one of the AIDS diagnosis criteria. To gain knowledge of RP infection in HIV-infected patients, we studied 145 RP cases detected in a cohort of 2,996 HIV patients in Puerto Rico between Jan. 1992-Dec. 2001. The RP prevalence was 4.8%; 77.2% were males and 62.1% were injecting drug users (IDU). At the time of RP diagnosis, the mean CD4+ T cell count was 93.8 cells/mm3, 59.3% were in antiretroviral treatment, 13% had received the pneumococcal vaccine and 84.8% had another AIDS related condition. Over 37% received two or more antiretroviral medications. The death rate in the first year after the RP diagnosis was 63.4%. A Cox proportional hazard analysis showed that CD4+ T cells <200/mm3 (p<0.05), history of toxoplasmosis (p<0.01), wasting syndrome (p<0.01), esophageal candidiasis (p<0.05) and lower number of antiretroviral medications (p<0.05) increased their mortality risk. The studied patients had a highly compromised immune system and a very low pneumococcal vaccination percent at the time of RP diagnosis. Low CD4+ T cells significantly increased the hazard and mortality risk of the cases studied. Antecedents of antiretroviral therapy in these patients ensure a better outcome with lower mortality. Efforts to increase the vaccination rate should reduce the RP incidence in our HIV-infected population.

Adult↗
PubMed2003

[Radiologic appearance of epiploic appendages and their complications].

A wide spectrum of pathologic processes can involve epiploic appendages, and primary epiploic appendagitis is the most frequent. Pathologic processes are today more frequently identified with the increased use of radiological assessment (ultrasound and computed tomography) of patients presenting with acute abdominal pain. Recognition of specific imaging abnormalities of complications enables the radiologist to make the diagnosis, thus allowing appropriate treatment.

Colon↗
PubMed2002

In vivo performance of a matrix-based quantitative ultrasound imaging device dedicated to calcaneus investigation.

We developed a prototype of an ultrasound (US) bone matrix densitometer, the BEAM scanner, in the context of a European Space Agency research program. This device, which is a contact imaging device, was designed to overcome the limitations of immersion devices in space. Broadband US attenuation (BUA) and speed of sound (SOS) parameters were calculated from the radiofrequency (RF) signal. The principle aim of this study was to evaluate in vivo performance in direct comparison with a currently available device (UBIS 3000, DMS, France). The short-term precision of the BEAM scanner for BUA was estimated at 2.8%, whereas it was 2.3% with UBIS 3000. The short-term precision for SOS was 0.3%, and this was the same as the coefficient of variation (CV) of the UBIS 3000. CVs of 3.4% and 0.6% for midterm precision were found for BUA and SOS, respectively, and UBIS 3000 scores were 3% and 0.4%, respectively. This preliminary study demonstrates the high performance of the BEAM scanner and its new concept offers a wide range of improvements and new applications.

Adult↗
PubMed2000

The shape of the HIV/AIDS epidemic in Puerto Rico.

This study presents information on AIDS patients in Puerto Rico, including their general sociodemographic profile, some risk-related parameters, characteristics of vulnerable groups, and elements of the clinical spectrum of the disease. Data were analyzed from the Puerto Rico AIDS Surveillance Program and available studies about the HIV/AIDS epidemic in Puerto Rico. A total of 23,089 AIDS cases was reported to the Puerto Rico AIDS Surveillance Program from January 1981 through February 1999. The HIV/AIDS epidemic has affected mostly males and females between the ages of 30 and 49, though cases have also been reported for other age groups. The cumulative proportion of persons with AIDS who are women has increased tremendously, from 11.4% for the 1981-1986 period to 21.6% for the entire 1981-1999 period. In Puerto Rico the category of injecting drug users (IDUs) accounts for the majority of the AIDS cases (52%), followed by heterosexual contact (22%), and men who have sex with men (17%). The three main diagnoses for AIDS on the island are wasting syndrome (30.7%); esophageal, bronchial, and lung candidiasis (29.4%); and Pneumocystis carinii pneumonia (26.8%). According to 1994 vital statistics for Puerto Rico, AIDS was the fourth-leading cause of death. The overall reported AIDS mortality rate was 42.0 per 100,000 persons, with the rate for males, 67.8, much higher than it was for females, 17.4. AIDS is the first cause of death among persons between 30 and 39 years old. Intense efforts are needed to better understand the epidemic in Puerto Rico and its biology, social and family impacts, and financial costs.

AIDS-Related Opportunistic Infections↗
PubMed1999

Hepatitis C virus-related fibrosing cholestatic hepatitis after cardiac transplantation: is azathioprine a contributory factor?

We report a patient who acquired hepatitis C virus (HCV) infection at cardiac transplantation, developing fibrosing cholestatic hepatitis (FCH) with early liver failure and a fatal outcome. FCH is a recently described clinicopathological entity characterized by a cholestatic pattern of serum liver enzyme abnormalities, a progressive course leading to liver failure, and a pathological picture defined by periportal fibrosis, neutrophilic infiltrates and signs of histological cholestasis. Although it was initially described secondary to hepatitis B virus infection, it has also been recently related to HCV infection. Some histopathological features consistent with azathioprine hepatotoxicity like cholestasis, perisinusoidal fibrosis, veno-subocclusive lesions and nodular regenerative hyperplasia were also observed in this case. Therefore, a direct cytopathic effect of HCV and the concurrent pathogenic role of azathioprine hepatotoxicity may be involved in the development of this complication of transplantation.

Azathioprine↗
PubMed1998

Management of major tracheobronchial injuries: a 28-year experience.

BACKGROUND: Tracheobronchial injuries are rare but potentially life threatening. Their successful diagnosis and treatment often require a high level of suspicion and surgical repairs unique to the given injury. METHODS: We reviewed our experience with 32 patients with tracheobronchial injuries treated over the past 28 years. RESULTS: Forty-one percent (13/32) of the injuries were due to blunt trauma and 59% (19/32), to penetrating trauma. Most penetrating injuries were located in the cervical trachea (74%), whereas blunt injuries were more commonly located close to the carina (62%). Fifty-nine percent of the patients required urgent measures to secure the airway. Penetrating injuries were usually diagnosed by clinical findings or at surgical exploration. The diagnosis of blunt injuries was more difficult and required a high index of suspicion and the liberal use of bronchoscopy. The majority of the injuries were repaired primarily using techniques specific to the injury, and most patients returned to their normal activity soon after discharge. CONCLUSIONS: A high level of suspicion and the liberal use of bronchoscopy are important in the diagnosis of tracheobronchial injury. A tailored surgical approach is often necessary for definitive repair.

Adolescent↗
PubMed1997

Yeast bcy1 mutants with stationary phase-specific defects.

Entry into the stationary phase requires the yeast BCY1 gene, which encodes the regulatory subunit of the cAMP-dependent protein kinase (cAPK). New bcy1 mutants, constructed by in vitro mutagenesis of the 3'-region encoding the cAMP-binding domains, were classified as early or late-acting mutants based on viability studies. The late-acting bcy1 mutants accumulated fewer stationary phase-specific Bcy1p isoforms and had decreased cAPK activity. This late-acting class is novel and dies after 7 days in culture, later than two previously reported stationary phase mutants, ubi4 and ard1.

Acetates↗
PubMed1996

Study of lymphocyte subpopulations in peripheral blood and secondary lymphoid organs in the goat using monoclonal antibodies to surface markers of bovine lymphocytes.

Monoclonal antibodies (mAbs) to surface markers of bovine lymphocytes MHC I, MHC II, B-cells, T-cells (CD2, CD4, CD8 and gamma/delta) and interleukin-2 (IL-2) receptor were tested in the goat by flow cytometry and using immunohistochemical methods. Samples from peripheral blood and secondary lymphoid organs (mesenteric lymph nodes, spleen and ileal Peyer's patch) were studied. The percentage of positive cells obtained by flow cytometry and its compartmentalisation in different tissue sections showed that the mAbs against MHC I, MHC II, CD2, CD4, CD8, gamma/delta and IL-2 receptor recognised lymphocyte subpopulations similar to those present in the bovine. However, the mAbs tested on B-cells reacted only partially in the recognition of this subpopulation.

Animals↗
PubMed1996

An emergency department-based protocol for rapidly ruling out myocardial ischemia reduces hospital time and expense: results of a randomized study (ROMIO).

OBJECTIVES: We tested the hypothesis that an emergency department-based protocol for rapidly ruling out myocardial ischemia would reduce hospital time and expense but maintain diagnostic accuracy. BACKGROUND: Patients with a missed diagnosis of myocardial infarction have a high mortality rate; however, providing routine hospital care to low risk patients may not be time- or cost-effective. METHODS: One hundred low risk patients were entered into the study and randomized either to an emergency department-based rapid rule-out protocol (n = 50) or to routine hospital care (n = 50). Patients receiving routine care were managed by their attending physicians. The rapid protocol included serum enzyme testing at 0, 3, 6 and 9h, serial electrocardiograms with continuous ST segment monitoring and, if results were negative, a predischarge graded exercise test. Study patients were also compared with 160 historical control subjects. RESULTS: Myocardial infarction or unstable angina occurred in 6% of patients within 30 days; no diagnoses were missed. By intention to treat analysis (n = 50 in each group), the hospital stay was shorter and charges were lower with the rapid protocol than with routine care (p = 0.001). Among patients in whom ischemia was ruled out, those assigned to the rapid protocol had a shorter hospital stay (median 11.9 vs. 22.8 h, p = 0.0001) and lower initial ($893 vs $1,349, p = 0.0001) and 30-day ($898 vs. $1,522, p = 0.0001) hospital charges than did patients given routine care. In historical control subjects, the hospital stay was longer (median 34.5 h, p = 0.001 vs. either group) and charges greater (median $2,063, p = 0.001, vs rapid protocol, p = 0.02, vs. routine care group). CONCLUSIONS: In low risk patients who present to the emergency department with chest pain, the rapid protocol ruled out myocardial infarction and unstable angina more quickly and cost-effectively than did routine hospital care.

Clinical Enzyme Tests↗
PubMed1994

An in vitro study of proximal femoral allograft strains in revision hip arthroplasty.

Bone allografts are used frequently to replace bone stock subsequent to total hip arthroplasty. Revision of the failed hip replacement results in a complex structure of allograft bone, host bone and a metal femoral component. To evaluate the mechanics of the allograft-implant-host bone structure at the time of surgery, a strain gauge study was undertaken with six fresh/frozen human femora. Under defined loading conditions, cortical strain distributions were measured for five different cases: (1) normal bone, (2) bone with a femoral implant, (3) bone with the femoral component and an osteotomy at the mid-stem level of the implant (i.e. to stimulate the proximal allograft-host junction around the femoral stem), (4) bone with an osteotomy and an implant cemented into the 'allograft' (i.e. the proximal end of the femur), and (5) bone with an osteotomy and the implant cemented into both the proximal 'allograft' and the distal host bone. The results showed that, prior to making the osteotomy, proximal femoral strains were decreased with the insertion of a femoral stem. These strains were further decreased when an osteotomy had been made. This strain distribution did not change when the stem was cemented into the proximal 'allograft' bone, or cemented into the proximal 'allograft' and distal host bone. The decreases in strain for these test cases implied that the discontinuity between the bony segments caused an extended reduction in the tensile or compressive stresses transmitted through the cortices.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Transplantation↗
PubMed1993

Effect of cigarette smoking on coronary patency after thrombolytic therapy for myocardial infarction. TEAM-2 Investigators. Second Multicenter Thrombolytic Trials of Eminase in Acute Myocardial Infarction.

Smokers have been reported to have an improved short-term prognosis after myocardial infarction when compared with nonsmokers. This study examines the effect of smoking status on infarct-related artery patency, a determinant of outcome, following thrombolytic therapy for acute myocardial infarction (AMI). To evaluate patency outcome by smoking status, the database of the Second Thrombolytic Trial of Eminase in Acute Myocardial Infarction was reviewed, and baseline characteristics were compared with infarct-related artery patency early (90 to 240 minutes) after thrombolysis in smokers versus nonsmokers. Smokers were younger (mean age 53 vs 59 years, p = 0.0001), more likely to be men (86 vs 73%, p = 0.008), normotensive (74 vs 58%, p = 0.004), to have an inferior infarction (66 vs 51%, p = 0.007), and tended to have higher hematocrits and fibrinogen levels than nonsmokers. Smokers had a significantly greater chance of achieving complete perfusion (Thrombolysis in Myocardial Infarction trial grade 3) (66 vs 51% p = 0.007) than nonsmokers, although the combination of grades 2 and 3 did not differ. After correcting for imbalances in baseline and angiographic variables, multivariate logistic regression identified smoking (odds ratio 1.8, p = 0.01) and infarct location (odds ratio 1.7, p = 0.03) as independent predictors of achieving grade 3 flow. The independent predictive component of smoking for achieving grade 3 patency after thrombolysis suggests the hypothesis that more active thrombogenic mechanisms may be operative in smokers, leading to a larger thrombus component that is more susceptible to lytic therapy.

Anistreplase↗