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Biomedical subjects

G Zajicek

Publications and source records attributed to G Zajicek.

175 records · Page 10Linked to original sources
PubMedDate not supplied

Cancer as a systemic disease.

Theories on the nature of cancer may be classified into two categories. One regards cancer strictly as a local phenomenon while the second looks at cancer as a local manifestation of a systemic process or disease. Although the first dominates current medical thought, the theories of immunological surveillance and of protovirus-oncogene implicitly assume cancer to represent a local manifestation of a systemic process or disease. This is supported also by epidemiological data forwarded in the present paper. In order to clarify the exact meaning of a systemic disease, cancer and its manifestation are compared with arteriosclerosis and its sequelae. Arteriosclerosis could be regarded as a prototype of a systemic disease. It presents itself clinically solely by its local manifestations, like myocardial infarction or stroke. These local manifestations may be followed by secondary systemic sequelae like congestive heart failure. In the same context, it is proposed to regard cancer as one systemic disease which presents itself clinically by local phenomena like carcinoma, lymphoma and sarcoma. These local manifestations may lead further to secondary systemic sequelae like metastasis.

Adult↗
PubMedDate not supplied

The right-left symmetry axis of the brain on CT.

The location of the brain's symmetry axis on computerized tomography (CT) images was mathematically formulated. A series of computer programs were written to "peel off" the skull and artifacts external to the skull. Image lines were then tested for right-left symmetry and in each line a pixel was selected which best represented the center of symmetry of the skull contents. The resultant calculated symmetry line of images with and without pathology was comparable to the visually determined symmetry axis. This method permits computed screening for right-left asymmetry.

Brain↗
PubMedDate not supplied

Turnover and migration of meibomian gland cells in rats' eyelids.

PURPOSE: The object of this study is to determine the velocity and migration course of meibomian gland cells. MATERIALS AND METHODS: Twenty-seven adult rats weighing about 200 g were injected intraperitoneally with a single dose of 0.5 microCi [3H]-thymidine/g body weight. Three rats were sacrificed 1 h after injection and 3 rats each on days 3, 6, 9, 12, 15, 18, 21 and 28 after injection. The eyes and eyelids were removed in one piece, fixed in formalin, embedded in paraffin and cut into 5-micron-thick vertical sections along the pupillary-optic nerve axis. The sections were dipped in liquid autoradiographic emulsion, exposed for 3 weeks, and stained with HE. Meibomian glands were scanned in the lower eyelid of the left eye using an ocular micrometer grid. In each scan the basement membrane of each acinus served as a point of origin. Along the entire gland two parameters were noted for each nucleus with three grains or more: the distance from the basement membrane (Y) and grain count. RESULTS: This study demonstrates for the first time the exact timing and direction of meibomian gland cell migration. We have shown that the cells migrate from the basement membrane to the center of the acinus at an average rate of 0.62 +/- 0.11 micron/day. Cell generation time was an average of 4.1 days. CONCLUSIONS: The stem cells of meibomian glands lie at the circumference of each acinus. These cells migrate synchronously with a constant velocity towards the center of the acinus, and are secreted as sebaceous material.

Animals↗
PubMedDate not supplied

Role of attrition and occlusal contact in the physiology of the rat incisor: IX. Impeded and unimpeded eruption in lathyritic rats.

In the rat, the administration of a lathyrogenic agent reduced both impeded and unimpeded eruption rates of incisors. Unimpeded eruption rates were greater than impeded eruption rates. The general eruption pattern in the experimental rats was, however, similar to that in the control rats. Thus, eruption was possible even in rats with a lathyrogenically impaired periodontal ligament.

Aminopropionitrile↗
PubMedDate not supplied

Role of attrition and occlusal contact in the physiology of the rat incisor: X. The part played by the periodontal ligament in the eruptive process.

Removal of the proliferating base of the rat incisor did not influence the rate of eruption which responded to changes in impediment to eruption in a fashion similar to that for control teeth. It is the peridontal ligament rather than the proliferating cells that is responsible for tooth eruption. The elements of the peridontal ligament apparently responsible for tooth movement are the mature fibroblasts.

Animals↗
PubMedDate not supplied

Inaccuracies in estimates of life expectancies of patients with bronchial cancer in clinical decision making.

Approximations of life expectancy in clinical decision making frequently assume constant disease-specific ("excess") mortality hazards over age at diagnosis and over time from diagnosis. This assumption is inconsistent with the longer relative survival of younger patients with bladder cancer and with the declines in mortality hazards from bladder and breast cancers over time from diagnosis. To estimate the error that may result from these assumptions, the authors derived excess mortality hazards from the Surveillance, Epidemiology and End Result (SEER) tumor registry for bronchial cancers stratified by age at diagnosis and time from diagnosis. They compared the life expectancies calculated by a model using an average constant annual cancer-specific mortality hazard over time from diagnosis with those calculated using data-derived cancer-specific annual mortality hazards that varied as a function of time from diagnosis. For younger patients with less advanced disease, the constant-average-mortality model underestimated life expectancies by up to 50% relative to those predicted by the time-variant model. For those over 75 years old at diagnosis, and for all patients with advanced disease, the constant-average-mortality model overestimated life expectancies by up to 65% relative to those predicted by the time-variant model. The authors conclude that predictions of life expectancy with bronchial cancer, and probably with other neoplasms, are limited by the widespread use of oversimplified methods of calculation and by the lack of data describing mortality hazards as a function of time from diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Pernicious cachexia: a different view of cancer.

Despite intensive effort to cure breast cancer, treatment generally fails, as evidenced by the age adjusted mortality from breast cancer. For 60 years, breast cancer mortality remained virtually constant. As treatment failed to improve the life prospect of the average patient, it is based on false premises, e.g., Halsted's hypothesis, according to which the tumor is the only threat to the patient. Yet there is more to cancer than just the tumor. Two hallmarks of cancer, cachexia, and paraneoplasia, are usually ignored, since it is assumed that they are caused by the tumor. But, what if it is the other way around, and cancer is first of all a cachexia accompanied by a tumor? At least this could explain why in most cancers treatment fails. Cancer is a chronic systemic disease with local manifestations. Like arteriosclerosis, that is also systemic and manifested solely by its local manifestations, e.g., stroke and myocardial infarction. In the same way as treatment of an ailing heart does not cure the underlying arteriosclerosis, tumor removal does not cure cancer, since being "metabolically" systemic. It is proposed here that carcinogens deplete a vital substance and induce a metabolic deficiency that ends in cachexia. In order to survive, the organism grows a protective organ, the tumor, that replenishes the missing substance. During pre-clinical phase of cancer, deficiency is slight and compensated even by a minute tumor. With time it gets worse and the tumor has to grow more and more in order to make up for the loss, causing pain and secondary damage to vital functions. The patient seeks help and the disease starts its clinical course. When deficiency worsens, the patient becomes cachectic and dies. Such a metabolic relationship exists in pernicious anemia, that illustrates how a tumor might be protective. Cancer is viewed here as pernicious cachexia induced by the loss of a vital metabolite and compensated by the tumor. Until the discovery of the missing substance, treatment ought to preserve the tumor and alleviate its secondary manifestations.

Cachexia↗
PubMedDate not supplied

Cellular changes in the mammary gland epithelium during the menstrual cycle. A computer image analysis study.

While examining fine needle aspirates of lesions, it became evident that preovulatory aspirates differed from postovulatory ones. Proliferation activity was noted in cells and in fragments aspirated during the luteal phase. In order to verify this observation, pairs of smears obtained during different phases of the menstrual cycle from eight fertile women were studied by computer image analysis. Using discriminant analysis based on nuclear features extracted from the digitized cell images, 84.87% of all cells were correctly classified as preovulatory or postovulatory, according to the smear of origin. When the classification was restricted to only the cells from each woman, a 100% correct identification of cell types was obtained, which supports the visual observation that there are cellular changes in the mammary epithelium correlated to the menstrual cycle. Since some proliferative changes may mimic atypia or malignancy, these findings suggest that it is advisable to perform needle aspirations of breast lesions during the preovulatory phase of the cycle.

Adolescent↗