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Biomedical subjects

J G Gonzalez

Publications and source records attributed to J G Gonzalez.

At least 19 recordsLinked to original sources
PubMed2005

Second eye of patients with unilateral neovascular age-related macular degeneration: Caucasians vs Chinese.

PURPOSE: To investigate the correlation between morphological features of choroidal neovascularisation (CNV) secondary to age-related macular degeneration (AMD) in the first eye and the severity of age-related maculopathy (ARM) in the fellow eyes in two racial groups: Caucasians and Chinese. PARTICIPANTS: A total of 135, fluorescein angiograms of patients with unilateral neovascular AMD and ARM in the fellow eyes were included in the study: 38 Caucasians from King's College Hospital, UK; 45 Caucasians from West Kent Eye Centre, UK; 52 Chinese from Hong Kong Eye Hospital, Hong Kong. MAIN OUTCOME MEASURES: CNV subtype in the affected eye and ARM severity in the second eyes. RESULTS: Although the proportion of CNV subtypes in the three groups were similar, the Chinese cohort showed significantly less ARM severity compared to the Caucasian cohorts (P < 0.05). CONCLUSION: Although drusen and retinal pigmentary changes may be prognostic indicators of CNV, this study suggest that other factors contribute significantly to the pathogenesis of CNV in AMD.

Aged↗
PubMed2005

Feasibility and morbidity of reversal of Hartmann's.

OBJECTIVE: Reversal of Hartmann's is a major surgical procedure and associated with substantial morbidity and mortality. METHOD: This study retrospectively analysed the data at a single centre over an eight-year period to assess the clinical results and morbidity of reversal of Hartmann's. RESULTS: One hundred and ten Hartmann's procedures were performed during the period. Only 66 (61%) of patients had a reversal. Advanced age and comorbidity were the primary reasons for not reversing. Complications among the 66 patients (36 males and 30 females) who underwent reversal occurred in 26 (41%). There were no deaths. Patients who underwent reversal were ASA 2 (60%), ASA 3 (25%) and ASA 4 (4.6%). Univariate analysis demonstrated a significant association between complications following reversal and ASA grade (P =0.01), and hypertension (P = 0.03) There was no correlation between the patient variables and anastomotic leakage. Multiple logistic regression analysis showed a significant influence of hypertension, smoking and ASA grade on complications. CONCLUSIONS: About 40% of patients who undergo Hartmann's procedure will not have a reversal. Reversal is a feasible operation for selected patients, but there is a high complication rate.

Adult↗
PubMed2000

Optimal digital filtering for tremor suppression.

Remote manually operated tasks such as those found in teleoperation, virtual reality, or joystick-based computer access, require the generation of an intermediate electrical signal which is transmitted to the controlled subsystem (robot arm, virtual environment, or a cursor in a computer screen). When human movements are distorted, for instance, by tremor, performance can be improved by digitally filtering the intermediate signal before it reaches the controlled device. This paper introduces a novel tremor filtering framework in which digital equalizers are optimally designed through pursuit tracking task experiments. Due to inherent properties of the man-machine system, the design of tremor suppression equalizers presents two serious problems: 1) performance criteria leading to optimizations that minimize mean-squared error are not efficient for tremor elimination and 2) movement signals show ill-conditioned autocorrelation matrices, which often result in useless or unstable solutions. To address these problems, a new performance indicator in the context of tremor is introduced, and the optimal equalizer according to this new criterion is developed. Ill-conditioning of the autocorrelation matrix is overcome using a novel method which we call pulled-optimization. Experiments performed with artificially induced vibrations and a subject with Parkinson's disease show significant improvement in performance. Additional results, along with MATLAB source code of the algorithms, and a customizable demo for PC joysticks, are available on the Internet at http:¿tremor-suppression.com.

Algorithms↗
PubMed1995

Plasma norepinephrine, myocardial damage and left ventricular systolic function in Chagas' heart disease.

The functional status of the sympathetic nervous system in Chagas' heart disease is still the subject of intense controversy. To determine the nature of the abnormalities of the sympathetic nervous system, we measured the plasma norepinephrine concentration of chagasic patients with varying degrees of myocardial damage. Thirty-six patients with positive serology for Chagas' disease were studied. Twenty patients were in Functional Class I (New York Heart Association), 10 were in Functional Class II and six were in Functional Classes III-IV. Cardiac catheterization was performed in 24 patients. The asymptomatic patients had a plasma norepinephrine concentration (121 +/- 37 pg/ml, mean +/- S.D.) not different from normal controls (103 +/- 59 pg/ml). The symptomatic patients, however, had a significantly elevated plasma norepinephrine concentration (665 +/- 354 pg/ml, P < 0.001). The baseline heart rate of the asymptomatic and symptomatic patients directly correlated with the plasma norepinephrine concentration (r = 0.69, P < 0.0001). The symptomatic patients had larger ventricular volumes, higher left ventricular end-diastolic pressures and lower ejection fractions than the asymptomatic patients and normal controls. The plasma norepinephrine concentration correlated linearly with the left ventricular end-diastolic volume (r = 0.77, P < 0.0001), and non-linearly with the ejection fraction (r = -0.70, P < 0.0001) and the left ventricular end-diastolic pressure (r = 0.53, P < 0.007). These results indicate that, in Chagas' heart disease as in most other cardiac diseases, sympathetic nervous system activation is a late and compensatory phenomenon. In other words, sympathetic activation is very likely related to the progressive impairment of left ventricular function.

Adult↗
PubMed1994

Illegal immigration in the presence of labor unions.

"This paper develops a general equilibrium framework of a two-sector economy which incorporates illegal immigration in the presence of labor unions. It demonstrates that stricter enforcement of immigration laws, by reducing the demand for or supply of illegal aliens, benefits all legal workers in the economy. The model is used to evaluate the impact of these policy changes on national income. Results indicate that national income does not necessarily fall when immigration controls are tightened. The existence of a union mitigates the negative welfare impact of a reduction in the number of illegal immigrants."

Demography↗
PubMed1993

Aggressive angiomyxoma in men. A report of two cases associated with inguinal hernias.

Aggressive angiomyxoma is a rare, locally invasive, but nonmetastasizing soft-tissue tumor that most commonly occurs in the pelvis or perineum of premenopausal women. In this article, we report two cases of aggressive angiomyxoma that occurred in middle-aged men. Although both patients initially presented with inguinal hernias, in other respects the two cases were significantly different. In one case, the tumor was small and found only incidentally at the time of surgery. In the other case, the tumor was extremely large, primarily involved the scrotal soft tissue, and was clinically thought to represent a testicular tumor.

Adult↗
PubMed1992

Stromal osteoclast-like giant cells in an adenosquamous carcinoma of the gallbladder.

We report a case an adenosquamous carcinoma of the gallbladder that extended to the proximal transverse colon. Metastatic tumor was present in regional lymph nodes and the liver. Microscopically, the tumor was composed of malignant epithelial cells that were cytokeratin-, epithelial membrane antigen-, and carcinoembryonic antigen-positive. The adjacent desmoplastic stroma of the primary tumor, as well as the metastasis, contained giant cells that morphologically resembled osteoclasts. Immunohistochemical studies showed that the giant cells were cytokeratin-, epithelial membrane antigen-, and carcinoembryonic antigen-negative but weakly alpha 1-antichymotrypsin-positive. While tumors containing osteoclast-like giant cells have been described in the breast, lung, liver, and thyroid, this is the first report of a tumor with this morphology originating in the gallbladder. The presence of the giant cells adjacent to both the primary and metastatic tumor and not at any other location suggests that the tumor cells are producing a substance that induces the formation of the nontumoral giant cells.

Adenocarcinoma↗
PubMed1992

Morphologic findings in bone marrow precursor cells in zinc-induced copper deficiency anemia.

Damage to the bone marrow elements, as shown by cytoplasmic vacuolization, has been reported in patients with acute alcohol intoxication, drug reactions, nutritional deficiencies, myeloproliferative syndromes, malignant hematologic conditions, some metabolic conditions, and in those treated with chemotherapeutic agents. A case of zinc toxicity with anemia, leukopenia, and cytoplasmic vacuolization of both myeloid and erythroid precursors is described. The patient described was a 30-year-old quadriplegic man who was receiving oral zinc to promote the healing of and prevention of decubitus ulcers. In the gut, dietary zinc interacts with copper in a competitive manner, and high levels of zinc can lead to copper deficiency. Zinc-induced copper deficiency anemia can be morphologically identified in the bone marrow preparations by cytoplasmic vacuolization of both myeloid and erythroid precursor elements.

Adult↗
PubMed1991

Relationship between c-erbB-2 immunoreactivity and thymidine labelling index in breast carcinoma in situ.

The relationship between the presence of the c-erbB-2 protein, demonstrated immunohistochemically with antibody 21N, and thymidine labelling index (TLI) has been studied in the in situ component of 70 cases of carcinoma of the breast. A significant association was found between high TLI and positive staining. Twenty of the 70 cases stained (29%) and of those that were stained 75% had a high TLI; 43% of those with a high TLI stained positively but only 14% of those with a low TLI stained positively. Strong correlations were seen between nuclear size and histological pattern and both 21N staining and TLI. The majority of carcinomas of comedo pattern with large nuclei were 21N positive and had a high TLI, whilst those with small nuclei and a predominantly cribriform/micropapillary appearance did not stain and had a low TLI. In tumours of mixed histological pattern there was less concordance between staining and TLI. The significance of these findings in relation to the biological behaviour of these tumours and their clinical management is discussed.

Breast Neoplasms↗
PubMed1989

Reactive eosinophilic pleuritis. A sequela of pneumothorax in pulmonary eosinophilic granuloma.

Pneumothorax is a frequent complication of pulmonary eosinophilic granuloma (EG) and can be a presenting manifestation of this disorder. Histologically the differential diagnosis of EG in patients presenting with pneumothorax includes reactive eosinophilic pleuritis (REP), a nonspecific inflammatory reaction commonly observed in association with ruptured pleural blebs. The authors present a case in which both EG and REP were found in lung tissue from a patient with recurrent pneumothorax. Immunohistochemical stains for lysozyme and S-100 protein assisted in differentiating these two lesions. Histiocytic cells in areas of EG were S-100 positive and lysozyme negative, whereas mononuclear cells in areas of REP were S-100 negative and lysozyme positive. It is emphasized that the finding of REP and pleural blebs in lung tissue from patients presenting with pneumothorax does not exclude the diagnosis of EG.

Adult↗
PubMed1988

Flow cytometric analysis of breast needle aspirates.

This study investigated two hypotheses: (1) sufficient cells may be obtained by needle aspiration of breast nodules to produce good flow cytometric DNA profiles; and (2) benign breast lesions do not produce aneuploid G0G1 peaks, and therefore a distinct aneuploid peak is sufficient for a diagnosis of malignancy. Breast specimens received in Surgical Pathology between December 1985 and February 1987 were aspirated, and the cells stained with propidium iodide for flow cytometric DNA analysis. A total of 344 specimens were aspirated, of which 204 (59%) were malignant and 140 (41%) benign. One hundred fifty-three malignant and 111 benign specimens contained sufficient cells for analysis. Cytologic smears were available for 177 malignant and 123 benign specimens. DNA histograms were considered diagnostic of malignancy if an aneuploid peak was present which contained at least 20% of the cells in the distribution, and had a DNA index greater than or equal to 1.2. Using these criteria, 73 of 153 (48%) carcinomas could be identified. None of the benign lesions satisfied these criteria. One fibroadenoma with atypical hyperplasia produced a distinct peak which contained less than 5% of the cells in the histogram, and had a DNA index of 1.25. Flow cytometric analysis provides objective data that complement the subjective cytologic interpretation of fine needle aspirates.

Aneuploidy↗
PubMed1988

Pituitary gland growth during normal pregnancy: an in vivo study using magnetic resonance imaging.

PURPOSE: Autopsy studies have shown that pregnancy results in physiologic pituitary enlargement. We used magnetic resonance imaging (MRI) to corroborate those findings in vivo. PATIENTS AND METHODS: Based on gestational age, 32 normal primigravid patients were divided into three groups: Group I (n = 10), less than 12 gestational weeks; Group II (n = 11), 13 to 26 gestational weeks; and Group III (n = 11), 27 gestational weeks or more. The pituitary dimensions and volumes in these groups were compared with those in 20 healthy nulliparous women (control group). RESULTS: MRI measurements showed a significant increase in pituitary volume in Groups I, II, and III when compared with the control group (p less than 0.001). Furthermore, there was an increase in pituitary volume between Groups I and II and between Groups II and III, although the former was not statistically significant (p greater than 0.05). At the end of pregnancy, the hypophysis had increased 2.6 mm in vertical, anteroposterior, and transversal dimensions, with an overall increase of 136 percent when compared with that of the control group. CONCLUSION: Baseline measurements of the normal enlargement of the pituitary gland that occurs during pregnancy could prove useful when evaluating pregnant patients with suspected pituitary tumors or lymphocytic hypophysitis.

Adolescent↗
PubMed1987

Synovial metaplasia of the skin.

Synovial metaplasia has been described in bone or soft tissues following surgical procedures or under experimental conditions. Three cases in which skin biopsies showed synovial metaplasia of the dermis are herein reported. The metaplastic foci were associated with cyst formation and transepidermal fistulae. All patients had a history of previous surgical procedures in the area, and in all, the lesions clinically resembled suture granulomas. Microscopically, the lesions bore a striking resemblance to hyperplastic synovium. The immunohistochemical studies showed strong staining with vimentin and scattered positivity with alpha-1-antichymotrypsin (alpha-1ACT) and lysozyme. No basement membrane antigens or elastic fibers were demonstrated. We believe that the name "metaplastic synovial cyst" is an appropriate pathologic designation for this entity. An increased awareness of its occurrence will help to establish its true incidence.

Adult↗
PubMed1986

Giant cell lichenoid dermatitis.

A case of drug-induced lichenoid dermatitis with an unusual epidermotropic multinucleated giant cell inflammatory response is reported. The patient is a 52-year-old white woman who is steroid-dependent because of long-standing systemic lupus erythematosus. At the time of presentation of her generalized papulosquamous pruritic eruption, she was taking oral antihypertensive medications (methyldopa and chlorothiazide). After discontinuation of these medications and local treatment with topical corticosteroids, the skin eruption dramatically improved. Microscopically, the skin lesions had a lichenoid inflammatory pattern, with multiple cytoid bodies, multinucleated giant cells, and a mixed chronic inflammatory infiltrate that included lymphocytes, histiocytes, and eosinophils.

Chlorothiazide↗
PubMed1982

Chuchuhuasha - a drug used in folk medicine in the Amazonian and Andean areas. A chemical study of Maytenus laevis.

In the high Amazonian basin a plant named chuchuasha, (or chuchuaso) is used in traditional medicine for several purposes in the form of an alcoholic extract. This plant, a Maytenus species, most probably Maytenus laevis, grows in the subandean region of the Amazonian basin (Peru, Ecuador, Colombia). Antitumor and anti-inflammatory properties were recently attributed to the extracts of the root bark of the plant. The composition of the extract of M. laevis from the Putumayo area of Colombia was studied in order to establish the active principle responsible for these activities. The presence of phenoldienones (tingenone, 22-hydroxytingenone), a catechin (4'-methyl-(-)-epigallocatechin) and proanthocyanidins (Ouratea-proanthocyanidins A and B) was established. The biological activities of these compounds confirm the properties of the extracts of the plant claimed by traditional medicine.

Antineoplastic Agents, Phytogenic↗