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Biomedical subjects

I Siegel

Publications and source records attributed to I Siegel.

At least 19 recordsLinked to original sources
PubMed1988

Variability of the pattern electroretinogram.

Conflicting results have been obtained concerning the parametric properties of the pattern electroretinogram. These discrepancies may be due to the large amount of variability inherent in recording amplitudes. We have found the variability within a single stimulus condition to be so large (ranging from 30% to 67% of the mean value) that it could mask any underlying spatial frequency tuning. Changing the stimulus conditions failed to significantly reduce the observed variability, although changing recording conditions produced some reduction. The use of a narrower rejection band, a greater number of sweeps, and placement of the reference electrode on the ipsilateral ear (as opposed to the ipsilateral temple) combined to decrease variability of the pattern electroretinogram within a single recording session; however, intersession variability remained high. Therefore one must be careful in evaluating data from this technique, and caution is advised in its clinical use.

Electroretinography↗
PubMed1988

Effects of short-term dietary restriction on survival of mammary ascites tumor-bearing rats.

We studied the effects of short-term dietary restriction on the survival of 3-4-month-old tumor-free and tumor-bearing Fisher rats. The diet-restricted food regimen consisted of alternate day ad libitum feeding followed by alternate day fasting. Diet-unrestricted control rats were fed ad libitum daily. Six tumor-free rats on the diet-restricted regimen compensated for the dietary restriction by an increase in food consumption during the alternate feeding days, and lost an average of only 2-3% of their weight in 13 days. Six tumor-free rats on a daily ad libitum feeding regimen gained an average of 6.8% in 15 days. The above dietary-restricted regimen was initiated 1 week before 24 rats were inoculated intraperitoneally with 15 million Mat 13762 ascites tumor cells. Sixteen of 24 (66.7%) diet-restricted tumor-bearing hosts and 5/24 (20.8%) diet-unrestricted tumor-bearing hosts survived at 9 days after tumor inoculation (p less than 0.005). Twelve of 24 (50%) diet-restricted tumor-bearing hosts, and 3 of 24 (12.5%) diet-unrestricted tumor-bearing hosts, survived at 10 days after tumor inoculation (p less than 0.025). Thus, the survival of tumor-bearing rats was enhanced by short-term relatively mild dietary restrictions. We suggest that relatively mild dietary restrictions should be included in clinical trials designed to inhibit cancer growth and enhance the survival of human cancer patients.

Animals↗
PubMed1988

The surgical treatment of chronic lateral humeral epicondylitis by common extensor release.

This retrospective study reports on the surgical treatment of chronic lateral epicondylitis. Thirty-four elbows were followed for an average of four years after surgery. Only those patients with persistent or recurrent local pain and muscle weakness, nonresponsive to conservative measures for at least six months, were considered for surgery. A complete release of the common extensor tendon permitted about a 1-cm distal muscle slide to a new resting length. The results indicate 73% excellent, 18% good, and 9% failures. Complete pain relief was obtained in 25 of 34 (73%) elbows, and eight of 33 (24%) had minimal residual symptoms that did not impair activity. There was no loss of range of motion in any patient, and 33 of 34 (97%) elbows had improved extremity muscle strength. All but one patient (97%) returned to their regular jobs on the average of five weeks after surgery. The gross and histologic findings were consistent with a degenerative process. This relatively simple outpatient procedure using Bier block anesthesia is recommended for carefully selected patients.

Adult↗
PubMed1987

Cytotoxic effects of free fatty acids on ascites tumor cells.

The effect of physiologic common free fatty acids (FFAs) on Mat 1376b ascites tumor cells in vitro and in vivo in F344 rats was investigated. Unsaturated fatty acids, such as palmitoleic (16:1), oleic (18:1), linoleic (18:2), linolenic (18:3), and arachidonic (20:4) acids, were significantly more effective killers of tumor cells in vitro than the corresponding saturated fatty acids of the same carbon length, including palmitic (16:0), stearic (18:0), and arachidic (20:0) acids. The saturated 16-carbon fatty acid (palmitic acid) was more toxic to tumor cells in vitro than the saturated 18-carbon (stearic) and 20-carbon (arachidic) acids. Injections of linoleic (18:2)-linolenic (18:3) acid combinations into rats inoculated with the tumor significantly enhanced the survival of the tumor-bearing animals. These results suggest that natural FFAs may under certain conditions be utilized as effective anticancer agents.

Animals↗
PubMed1986

Inhibition of sperm motility and agglutination of sperm cells by free fatty acids in whole semen.

The effects of a serial dilution of linoleic acid on human spermatozoa in whole semen was tested on 21 semen samples obtained from 11 normal volunteers. The minimal concentration of linoleic acid required to stop the movement of at least 75% of the moving sperm ranged from 1 to greater than 100 mg/dl. Fifteen of 21 (71%) of the semen samples were inhibited by added free fatty acids (FFA) concentrations that were less than or close to the physiologic concentration ranges of FFA in blood plasma (1 to 30 mg/dl). The immobilized sperm often formed aggregates similar to those formed by the action of autoantibodies against sperm cells. Preliminary studies conducted on a variety of other FFA have indicated that oleic acid (18/1) was less toxic than linoleic acid (18/2) and that linolenic acid (18/3) was more toxic than linoleic acid. The saturated FFA palmitic acid (16/0) and stearic acid (18/0) at concentrations up to 100 mg/dl showed little or no toxicity to sperm cells. It is suggested that FFA toxicity be included among physiologic factors that affect the motility and spontaneous aggregation of sperm cells.

Ascorbic Acid↗
PubMed1984

Lymphocyte subsets in endometriosis.

Recent investigations suggested a possible immunologic etiology for endometriosis. To determine whether cellular immunity may be affected in patients with endometriosis, peripheral lymphocyte populations were investigated in 31 confirmed endometriosis patients and 22 control patients. No statistical differences in OKT3, OKT4, OKT8, OKM1, and OKTa1 cells could be observed. Total lymphocyte numbers were within normal ranges for both groups. Helper/suppressor ratios were not statistically different and were in a normal range for both groups. It is concluded that numeric differences in lymphocyte subpopulations represent only a very unlikely contributing factor in a potential immunologic etiology of endometriosis.

Antibodies, Monoclonal↗
PubMed1983

Immunology of pregnancy.

Even though the paradox of the fetal allograft is still not completely understood, advances in reproductive immunology have made various immunological mechanisms apparent which seem to play a part in the tolerance of the fetal allograft by a seemingly normal maternal immune system. Pregnancy immunology is, however, not only restricted to the understanding of the transplant analogy of pregnancy, but has also achieved clinical significance through our increased awareness of immunological mechanisms being implicated in various pregnancy disorders. A review is presented outlining our present understanding of both basic immunological mechanisms and the normal process of pregnancy as well as those abnormal mechanisms which may be implicated in pathological states.

Antigen-Antibody Complex↗
PubMed1983

Developmental changes of components of the red cell immune system in the rabbit.

Red cell immune adherence (RCIA) occurs not only in primates but also in nonprimates such as the rabbit. We utilized the rabbit as an animal model to study developmental changes in the immune functions of rabbit red cells. Significant differences between adult and newborn rabbits were found. RCIA-receptor activity of the newborn rabbits was significantly larger than that of adult rabbits (p less than 0.0005). Serum RCIA inhibiting factor, which completely prevented any detectable RCIA, was evident in about 40% of adult but not in any of the newborn rabbits (p less than 0.01). RCIA-inhibiting factor was also detectable in three out of eight pregnant rabbits but did not cross the placenta into the rabbit fetus. High concentrations (33%-100%) of most adult sera but not of newborn sera inhibited RCIA (p less than 0.001). It is suggested that, like the thymus, red cell immune function may reach its peak activity during early developmental periods. The red cell immune function may be essential for the removal of antigen-antibody complement complexes from the fetal circulation and may participate in the activation of T suppressor cells which adhere to autologous red cells.

Age Factors↗
PubMed1982

Immune complexes in pregnancy. III. Immune complexes in immune complex-associated conditions.

Seventeen patients during the third trimester of pregnancy with associated immune complex disease and/or immune complex state and their infants' cord blood were investigated for the presence of immune complexes. In comparing maternal levels of immune complex in normal third-trimester pregnancies to the study group, no statistical significant difference was noted. However, levels in cord blood were significantly lower (p less than 0.0025) than levels in paired maternal samples, but were found to correlate significantly (p less than 0.002). On the basis of the immunochemical analysis of selected pairs, the conclusion is that IgG-containing immune complexes may be responsible for this observed correlation and may represent the normal physiologic situation of pregnancy, whereas IgM-containing immune complexes may represent pathologic, and, therefore, abnormal, states. The suggestion is that the presence of such IgM-containing immune complexes may become predictive of fetoplacental compromise.

Antigen-Antibody Complex↗
PubMed1981

The red-cell immune system.

It is suggested that red cells have an immune function as well as a respiratory one. Adherence of red cells to antigen-antibody-complement complexes (red-cell immune adherence) has been observed in primates and in rabbits and may represent a basic immune phenomenon that is common to at least all mammals. It is estimated that 95% of C3b receptors in the human circulation are located on red cells and that an antigen-antibody-complement complex has a 500-1000 times greater chance of being removed from the circulation by a red cell than by a white cell. That red cells also adhere to autologous thymocytes and T cells suggests that they may act as intermediaries bringing antigens and T cells together.

Animals↗
PubMed1981

Permeability of gingival sulcular epithelium in the development of scorbutic gingivitis.

Young adult nonhuman primates were initially fed an ascorbic-acid free diet and, subsequently, a diet with a suboptimal level of the vitamin. Following approximately 12 weeks of this dietary regime, five of seven experimental animals of the gingival sulcular epithelium to 3H-inulin, but not to 14C-butyric acid or 14C-urea, had increased significantly (+86%, P less than 0.01) in the experimental group as compared to ad libitum or pair-fed controls. This defect in the intercellular permeability barrier of the sulcular epithelium could have contributed to the pathogenesis of scorbutic gingivitis.

Animals↗