Search PubMed⌕ Search

Biomedical subjects

S Ullman

Publications and source records attributed to S Ullman.

At least 19 recordsLinked to original sources
PubMed1992

Low-level aspects of segmentation and recognition.

This paper discusses two problems related to three-dimensional object recognition. The first is segmentation and the selection of a candidate object in the image, the second is the recognition of a three-dimensional object from different viewing positions. Regarding segmentation, it is shown how globally salient structures can be extracted from a contour image based on geometrical attributes, including smoothness and contour length. This computation is performed by a parallel network of locally connected neuron-like elements. With respect to the effect of viewing, it is shown how the problem can be overcome by using the linear combinations of a small number of two-dimensional object views. In both problems the emphasis is on methods that are relatively low level in nature. Segmentation is performed using a bottom-up process, driven by the geometry of image contours. Recognition is performed without using explicit three-dimensional models, but by the direct manipulation of two-dimensional images.

Computer Simulation↗
PubMed1992

[Leprosy--still a possibility in Denmark].

A case of borderline tuberculoid leprosy in a 27 year old woman from the Philippines is presented. The diagnosis was made after repeated biopsies. Only a single mycobacterium was present and the histology of the initial biopsies was inconclusive. This case emphasizes that leprosy is still imported to Denmark, and that the diagnosis is often difficult and delayed for years.

Adult↗
PubMed1992

Clinical manifestations in patients with autoantibodies specific for nuclear lamin proteins.

IgG antibodies to nuclear lamin proteins have been found in serum samples from 31 patients using immunofluorescence on HEp-2 cells, Western blotting, and enzyme-linked immunosorbent assay, performed against a nuclear lamina preparation from Ehrlich ascites tumor cells. Antilamin antibodies were most prevalent among patients with nonerosive, seronegative polyarthritis, or patients showing serum antiphospholipid reactivity as well. It is possible that anti-lamin antibodies may thus be a marker for a subgroup of polyarthritis patients who have a different prognosis from that of those with seropositive rheumatoid arthritis. The mechanism for the combined occurrence of anti-lamin and antiphospholipid autoantibodies is obscure. Future studies will answer whether these two antibodies represent a distinct antibody profile in patients with antiphospholipid antibody syndrome.

Adolescent↗
PubMed1992

Lipoid proteinosis.

Lipoid proteinosis (Urbach-Wiethe disease) is a rare, recessively inherited disorder that is characterized by the deposition of hyaline-like material in the skin, oral cavity, and other tissues. It usually appears in infancy with hoarseness. We report a case of lipoid proteinosis in a 10-year-old boy that demonstrates the characteristic clinical, histologic, and ultramicroscopic features of this disease.

Child↗
PubMed1991

[Systemic lupus erythematosus. 1. Disease manifestations, infections, thrombotic episodes, causes of death and survival in a case load of 173 patients followed for 13.9 years].

One hundred and seventy-three patients had systemic lupus erythematosus according to the 1982-ARA-criteria. The mean disease duration at the time of the study was 16.4 years, and the patients were followed by three Copenhagen clinics for a mean of 13.9 years until 1987/88 or death. Half of the patients had nephropathy, 61 patients developed severe infections, and 39 patients had thrombotic episodes. Fifty-six patients died during the observation period, 24 due to active lupus (12 of kidney failure), 12 because of infections, and 11 because of atherosclerotic cardio-vascular disease. The patients had 10-, 15- and 20-year survival rates of 80, 65 and 48 per cent. The deaths were evenly distributed throughout the observation period.

Adult↗
PubMed1991

[Systemic lupus erythematosus. 2. Factors of predictive significance for survival].

Sixty-one of 173 patients with systemic lupus erythematosus followed for a mean of 13.9 years had severe infections which influenced their survival more than could be accounted for by the mortality (20 per cent) caused by the infections. Patients with infections had more SLE manifestations than patients without infections, and they died of lupus manifestations more often than patients without infections. Patients who went into a permanent remission and patients who died of lupus differed most markedly by the rates of infection. The rate of infection was increased more than tenfold in patients treated with high dosages of glucocorticoid compared with patients who received low dosages. Treatment with cytostatics influenced the rate of infections to a moderate degree. Nephropathy also influenced survival but half of the patients with nephropathy maintained a normal plasma creatinine in spite of the long observation period. 16 per cent of the patients with nephropathy died of kidney failure or are receiving chronic hemodialysis.

Adult↗
PubMed1991

Short- and long-range processes in structure-from-motion.

Human ability to detect 3-D structure in an array of 2-D moving dots was tested. Under limited exposure time, we found high detection rates only when the 2-D motion was restricted to the spatio-temporal region of short-range motion. Long-range moving dots failed to produce a strong impression of 3-D structure and yielded only weak detection rates. This result is consistent with the view that the processing of long-range motion is more serial than that of short-range motion.

Depth Perception↗
PubMed1991

Xeroderma pigmentosum lesions related to ultraviolet transmittance by clothes.

Xeroderma pigmentosum is associated with severe actinic degeneration of the skin. Our patient with xeroderma pigmentosum showed increasing actinic damage in some areas covered by clothes. We therefore performed a complete evaluation of the patient's exposure to ultraviolet radiation. This included transmission measurements of the patient's clothes, glasses, and car windows. The transmission of UVB (280 to 320 nm) by the clothes varied from none to 17.8%. The transmitted UVB radiation was proportional to the clinical manifestations of xeroderma pigmentosum. The patient's wardrobe was changed, and UVA-blocking film was applied to the windows of the car and house. A decline in manifestations was seen after 18 months of improved ultraviolet protection.

Adult↗
PubMed1991

Visual curve tracing properties.

Subjects decided whether 2 dots were on the same curve or 2 different curves, and the curvature of the curves or the proximity of other (distractor) curves to the target curve was varied. Response time increased as the arc length of the curve connecting the 2 dots increased, suggesting that the curve was traced to perform the task. Tracing rate was faster for low- than high-curvature contours and was increasingly slower as distractor contours were increasingly proximal to the traced curve. Proximity results were predicted by a model in which response time depends on the ratio of the distance between the dots and the distance between adjacent lines. Curve tracing operations used to integrate information along contours are sensitive to several properties of the contours. The implications of the sensitivity of tracing operations to these curve properties are discussed.

Adult↗
PubMed1990

Autoantibodies to lamins A and C in sera of patients showing peripheral fluorescent antinuclear antibody pattern on HEP-2 cells.

Lamins A, B, and C are the major proteins of a polymeric structure called nuclear lamina, which is intercalated between chromatin and the inner membrane of the nuclear envelope. Using immunofluorescence on HEp-2 cells, specific enzyme-linked immunosorbent assay, and Western blotting performed against nuclear lamina preparation from Ehrlich ascites tumor cells, we characterized three patients, whose sera contained antibodies to nuclear lamins. The reaction pattern observed in two of the patients may result from single or combined occurrence of anti-lamin A and C antibodies. The third patient had antibodies that probably recognized an epitope in the carboxy-terminal region of lamin C. The sera were donated by a heterogeneous group of patients, and no common clinical or laboratory signs seemed to link them together.

Adult↗
PubMed1990

Generalized morphea with blisters. A case report.

A patient suffering from generalized morphea developed blisters in the morpheic plaques on her buttocks. The plaques had an increased concentration of serum aminoterminal propertice of type III procollagen, an echo response and thickened skin on ultrasound scanning, and compact bundles of collagen fibrils with bimodal distribution of the diameters. The blisters appeared as an echo-free band in the subepidermal zone by ultrasound scanning. Electron microscopy revealed blisters in the upper papillary dermis, surrounded by degraded collagen fibrils.

Aged↗
PubMed1989

Aligning pictorial descriptions: an approach to object recognition.

This paper examines the problem of shape-based object recognition, and proposes a new approach, the alignment of pictorial descriptions. The first part of the paper reviews general approaches to visual object recognition, and divides these approaches into three broad classes: invariant properties methods, object decomposition methods, and alignment methods. The second part presents the alignment method. In this approach the recognition process is divided into two stages. The first determines the transformation in space that is necessary to bring the viewed object into alignment with possible object models. This stage can proceed on the basis of minimal information, such as the object's dominant orientation, or a small number of corresponding feature points in the object and model. The second stage determines the model that best matches the viewed object. At this stage, the search is over all the possible object models, but not over their possible views, since the transformation has already been determined uniquely in the alignment stage. The proposed alignment method also uses abstract description, but unlike structural description methods it uses them pictorially, rather than in symbolic structural descriptions.

Form Perception↗
PubMed1989

The development of AIDS or AIDS-related conditions in a cohort of HIV antibody-positive homosexual men during a 3-year follow-up period.

One hundred and thirty-three homosexual men seropositive for the antibody against human immunodeficiency virus (HIV) were enrolled in a prospective study in 1984-85. The 3-year cumulative incidences of the acquired immunodeficiency syndrome (AIDS) and AIDS-related conditions, by life-table analyses, were 18% and 34%. The cumulative incidence of immune deficiency defined as CD4 lymphocytes less than 0.5 x 10(9) l-1 was 70% at 3 years. Absence of antibodies to p24 antigen, HIV antigenaemia, CD4 lymphocytes less than 0.3 x 10 l-1 and elevated serum level of IgA were significantly associated with the development of AIDS. There was no association between disease progression and persistent generalized lymphadenopathy. When adjusted to the probable year of infection, these results are in accordance with previous cohort studies. It is concluded that most, or all, subjects seropositive for HIV will develop progressive loss of CD4 lymphocytes followed by clinical signs of immune deficiency, and that differences among previous cohorts with respect to disease progression are probably due to differences in the duration of infection.

AIDS-Related Complex↗
PubMed1987

Lymphocyte transformation response to pokeweed mitogen as a predictive marker for development of AIDS and AIDS related symptoms in homosexual men with HIV antibodies.

To identify factors that may predict the development of the acquired immune deficiency syndrome (AIDS) or AIDS related symptoms various immunological measurements were studied in a group of homosexual men attending screening clinics for AIDS in Copenhagen. Fifty seven men whose ratio of T helper lymphocytes to T suppressor lymphocytes (CD4:CD8 ratio) was less than 1.0 before the study began were included. Forty two were positive for antibody to the human immunodeficiency virus (HIV), of whom 38 were reinvestigated after a median observation period of 10 months. Among the seropositive men the transformation responses to pokeweed mitogen and cytomegalovirus and the absolute count of CD4 positive lymphocytes were the most common abnormal values. In particular, a low relative response to pokeweed mitogen on initial investigation correlated with a worsened clinical condition on reinvestigation. The risk of a worsened clinical condition was 55 times higher in seropositive men whose responses to pokeweed mitogen were low than in other seropositive men. The corresponding relative risks for low transformation responses to cytomegalovirus and for a decreased absolute count of CD4 positive lymphocytes were 18 and six. The relative response to pokeweed mitogen is therefore a very sensitive short term predictive marker of the clinical condition of seropositive patients who have a CD4:CD8 ratio of less than 1.0.

AIDS-Related Complex↗