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Biomedical subjects

K Banovac

Publications and source records attributed to K Banovac.

At least 19 recordsLinked to original sources
PubMed1992

Effect of mast cell chymase on the morphology of thyroid cells in vitro.

We studied the effect of mast cell chymase on the thyroid cells in culture. Rat serosal mast cells, similar functionally to connective tissue mast cells, were obtained after lavage of the peritoneal cavity and lyzed by freezing. The resulting lysate was used as crude enzyme preparation. Mast cell chymase was purified from the crude preparation by anion exchange chromatography. Crude and purified chymase incubated with thyroid cells induced cellular retraction, the appearance of long processes and gradual cell detachment from the substratum. The effect of the enzyme was not cytotoxic. The immunofluorescence studies of thyroid cells showed a decreased amount of polymerized actin and tubulin after incubation with chymase. Neutral protease inhibitor abolished the effect of crude and purified chymase on thyroid cell morphology. The above findings suggest that mast cell chymase may have a function in the control of cell morphology and cell-matrix interaction.

Actins↗
PubMed1992

The effect of mast cell chymase on extracellular matrix: studies in autoimmune thyroiditis and in cultured thyroid cells.

In the first part of the study we analyzed the morphology of mast cells in autoimmune thyroiditis of BB/W rats. In the early stage of thyroiditis mast cells showed exocytosis of granules into the interstitium; this was associated with disorganization of the extracellular matrix and the appearance of a translucent ground substance in stroma. Mast cells were not seen in the mononuclear infiltrates in the later stages of thyroiditis. In order to further study the effect of mast cells on the extracellular matrix, we evaluated the effect of mast cell lysate and purified chymase on the matrix of cultured thyroid cells. Mast cells were obtained from peritoneal cavity; mast cell chymase was purified by anion exchange chromatography. After exposure to chymase there was a reduction of pericellular fibronectin in cultured thyroid cells, while laminin in matrix remained unchanged. Similarly, as found by gel electrophoresis, soluble fibronectin and vitronectin were digested by chymase in the reaction mixture. Cell attachment on both fibronectin and vitronectin was significantly decreased upon exposure of matrix proteins to chymase. The effects of chymase were abolished by enzyme inhibitor phenylmethane sulfonyl fluoride. These data suggest that mast cells possess proteolytic enzymes capable of digesting different host proteins which may have a role in the thyroid cell interaction with the surrounding matrix.

Animals↗
PubMed1991

Autoregulation of cerebral blood flow in patients with orthostatic hypotension after spinal cord injury.

Two groups of patients who developed orthostatic hypotension (OH) after spinal cord injury (SCI) were studied. In the first group all patients (4 females and 6 males) were asymptomatic, whereas in the second group (1 female and 9 males) all had clinical manifestations of hypotension. All but 3 patients were tetraplegic, and these patients were paraplegic above the T6 level. For this study blood pressure (BP), heart rate and cerebral blood flow (CBF) velocity were measured simultaneously on a tilt table at 0, 30, 60, and 80 degrees. Cerebral blood flow in the middle cerebral artery was measured bilaterally utilising the transcranial Doppler technique. In asymptomatic patients the mean baseline (0 degrees) BP (110 +/- 16/70 +/- 77 mm Hg systolic/diastolic) was not significantly different from the BP (106 +/- 16/68 +/- 11 mm Hg) of symptomatic patients. The mean maximal change in BP during tilting in the asymptomatic group (-23 +/- 10/10 +/- 7 mm Hg) was also not significantly different when compared to the symptomatic group (-29 +/- 13/11 +/- 6 mm Hg). CBF in the symptomatic group during the hypotensive reaction at 80 degrees was 32.5 +/- 5 cm/sec, while at the same body position in the asymptomatic group it was 40.9 +/- 8 cm/sec (significant at the p less than 0.02). In addition, CBF decreased in the symptomatic group at 80 degrees to 55.5 +/- 9.6% of baseline, while in the asymptomatic group the fall was 69.3 +/- 7.2% (p less than 0.001). Our data suggest that autoregulation of CBF rather than systemic BP plays a dominant role in the adaptation to OH in patients with SCI.

Adult↗
PubMed1991

Decreased incidence of urinary tract infections in patients with spinal cord injury: effect of methenamine.

This study was designed to determine the effect of methenamine on the frequency of urinary tract infections (UTI) in hospitalized patients after spinal cord injury. The study included 56 patients with neurogenic bladder dysfunction treated with intermittent catheterization. A group of 34 patients was treated with methenamine, 1g twice daily; the other group of 22 patients was the control group receiving no antimicrobial therapy. On a weekly basis urine samples from all patients were obtained for urinalysis and culture. A total of 500 urine samples were analyzed. The patients treated with methenamine had 23.4% positive urine cultures which was significantly lower than 57.5% in the untreated control group (p less than 0.001). Our data suggest that methenamine therapy is an effective prevention of UTI in paralyzed patients with neurogenic bladder dysfunction during the rehabilitation in hospital.

Bacteriuria↗
PubMed1989

A study of hepatic metabolism of thyroxine in BB/W rats treated with L-thyroxine.

The effect of thyroxine (T4) on T4 conversion to triiodothyronine (T3) and reverse T3 (rT3) was studied in BB/W rats. A colony of 38 BB/W rats was obtained and half were treated with thyroxine (T4), 1 mg per liter of drinking water. At 106 days of age the following groups were identified: nondiabetic, no T4 treatment, 8 rats; nondiabetic, T4 treated, 8 rats; diabetic, no T4 treatment, 10 rats; diabetic, T4 treated, 7 rats. All animals with diabetes were treated with insulin. T4 conversion to T3 and rT3 was assessed in liver homogenates in 0.1 M Tris-HCl buffer, pH 7.4, with or without 5 mM dithiothreitol (DDT). Serum T4 and rT3 were significantly elevated in both T4-treated groups (P less than 0.001), while serum T3 was not affected in either. Basal T4 deiodination to T3 by the liver homogenate did not change on treatment with T4; the addition of DTT increased T3 production in the homogenate from T4 treated nondiabetic animals (P less than 0.05). In both nondiabetic and insulin-treated diabetic rats there was no effect of T4 on the rate of rT3 production. Since, in the rat, 30-40% of circulating T3 is a direct contribution of thyroid gland secretion, and that would be absent in our T4-suppressed animals, the normal serum T3 may reflect increased absolute peripheral T3 production from the greater concentration of circulating T4.

Animals↗
PubMed1989

Intrathyroidal mast cells express major histocompatibility complex class-II antigens.

We studied the expression of major histocompatibility complex (MHC) class-II antigen in mast cells of rat thyroid glands. In the normal rat thyroid, mast cells express MHC class-II antigen. In BioBreeding Wistar (BB/W) rats, the strain of animals prone to develop spontaneous autoimmune thyroiditis, the number of MHC class-II-positive mast cells was significantly higher than in normal rats (p less than 0.01). Furthermore, intrathyroidal mast cells in BB/W rats showed an increased MHC class-II expression before the appearance of circulating thyroid antibodies or the infiltration of tissue with mononuclear cells. These data suggest that mast cells in the rat thyroid gland may have a function as antigen-presenting cells.

Animals↗
PubMed1989

Are the mast cells antigen presenting cells?

Mast cells have an important role in allergic reactions secreting histamine and other mediators of immediate hypersensitivity. In the present study we evaluated major histocompatibility complex (MHC) class II antigen expression in mast cells and their possible role in antigen presentation. In rats, 10% of mast cells isolated from the pleural cavity expressed MHC class II antigen; after incubation with gamma interferon (INF) 80% of the cells were positive. These findings suggest that mast cells, in addition to their secretory function in allergic reactions, may also function as antigen presenting cells.

Animals↗
PubMed1989

Evidence of hyperthyroidism in apparently euthyroid patients treated with levothyroxine.

A concentration of serum thyroxine (T4) above the accepted normal range has recently been recognized to result from commonly prescribed replacement dosages of levothyroxine sodium. To determine if the high levels of serum T4 have undesirable metabolic effects, despite the fact that the subjects are accepted as euthyroid, we studied 28 patients receiving long-term levothyroxine therapy; 19 patients were considered to be receiving replacement dosages and nine suppressive dosages of levothyroxine. To assess the effect of levothyroxine on target tissue, we measured the thyrotropin response to protirelin and systolic time intervals obtained by simultaneous electrocardiography and echocardiography. Thyrotropin response to protirelin was suppressed in patients with elevated serum T4 levels and normal serum triiodothyronine levels. These patients also had shortened systolic time intervals typical of hyperthyroidism. Our data indicate that commonly given replacement dosages of levothyroxine may induce undesirable metabolic consequences and that these patients perhaps ought to be seen as having "subclinical hyperthyroidism." The prescribed dosage of levothyroxine as therapy for hypothyroidism is still frequently excessive.

Adolescent↗
PubMed1988

The effect of thyroxine on spontaneous thyroiditis in BB/W rats.

The effect of T4 on the incidence of lymphocytic thyroiditis and on titers of antibodies to thyroglobulin and thyroid microsomal antigen was studied in BB/W rats that are prone to develop spontaneously autoimmune thyroiditis and diabetes. Thirty-three animals were separated in two groups. Rats in one group had 1 mg T4 per liter of drinking water, and the other group was given no T4. After 3-4 months of therapy the T4-treated group had a reduced production of antibody to thyroglobulin (p less than 0.05) and to microsomal antigen (p less than 0.005) and a significantly lower frequency of lymphocytic thyroiditis (p less than 0.05). Our data are consistent with previous findings in experimentally induced thyroiditis in rats and suggest that T4 has an immunosuppressive effect.

Animals↗
PubMed1985

Thyroidal thyroxine and triiodothyronine in autonomously functioning thyroid nodule and paranodular tissue.

Thyroidal thyroxine (T4), triiodothyronine (T3), thyroglobulin (Tg) and T4/T3 ratio were investigated in nodular and paranodular tissue from 16 patients with autonomously functioning thyroid adenomas. The concentration of T4 and T3 in the nodule were 97.7 +/- 20.5 (Mean +/- SE) and 10.2 +/- 2.4 micrograms/g wet weight (w.w.). Both iodothyronines were significantly lower in paranodular tissue (22.6 +/- 4.8 and 1.45 +/- 0.32 micrograms/g w.w., respectively), but with disproportionately decreased T3 which resulted in T4/T3 ratio (25.4 +/- 6.4) higher than in adenoma tissue (11.2 +/- 1.6). In patients with high normal or supranormal serum T3 concentration, thyroidal concentration of T3 in adenoma tissue was higher (15.6 +/- 5.0 vs. 6.3 +/- 1.2 micrograms/g w.w.) and T4/T3 ratio lower (8.05 +/- 2.1 vs. 13.2 +/- 1.9) than in patients with normal serum T3. The results suggest that thyroid release of T3 from adenoma is relatively higher than T4 in patients with autonomously functioning thyroid nodules and increased peripheral T3.

Adenoma↗
PubMed1983

Increased serum reverse triiodothyronine in patients with hyperemesis gravidarum.

Thyroid function and pituitary responsiveness to TRH were studied in patients with hyperemesis gravidarum. Serum T3 and T4 concentrations were normal. Serum TBG levels in hyperemesis were normal for gestation, and the T4:TBG ratio was in the euthyroid range. In all patients a normal TSH response to TRH was found. Mean serum rT3 concentration was increased by 31% as compared to a control group of normal pregnant women (P less than 0.001). The data suggest that in patients with hyperemesis gravidarum there is: (a) normal function of the thyroid gland and pituitary-thyroid axis, (b) an enhanced peripheral conversion of T4 to rT3.

Adult↗
PubMed1982

Reduction of total and free triiodothyronine in serum after abortion.

The effect of abortion on serum concentration of thyroid hormones was studied in 11 normal women. After abortion, serum free and total T3 fall significantly, while free and total reverse T3, T4, TSH and TBG in serum show no significant variation. These data suggest that surgical stress in normal subjects may only influence 5'-deiodinase activity, and that the peripheral conversion of T4 to active T3 and inactive rT3 are controlled by different mechanisms.

Abortion, Spontaneous↗
PubMed1981

Absence of thyroid-stimulating antibody and long acting thyroid stimulator in relatives of Graves' disease patients.

None of the 76 euthyroid relatives of patients with Graves' disease had detectable LATS in their serum nor was thyroid-stimulating antibody (TSAb), assessed by an increment of cAMP in human thyroid slices, detected in any of the 60 sera tested. Seven of 41 were slightly positive for TSH binding-inhibiting immunoglobulin (TBII). Nineteen of 73 sera were positive (greater than 1:1600) for antibody to thyroid antimicrosomal antigen, of which 4 were also positive (greater than 1:400) for antibody to thyroglobulin; 3 of the 19 had a slightly elevated basal TSH which rose excessively after TRH. Thus, although these euthyroid relatives had evidence of thyroid immunological defects, a thyroid-stimulating antibody was not found.

Antibodies↗
PubMed1980

Clinical significance of assay of thyroid-stimulating antibody in Graves' disease.

We correlated thyroid-stimulating antibody (direct thyroid stimulation method) with the clinical course of 187 patients with Graves' disease. Of 64 patients with newly diagnosed hyperthyroidism, 59 were positive; 36 of 38 patients tested early in therapy were positive. Twenty-eight patients received antithyroid drug therapy, and thyroid-stimulating antibody was measured at cessation of therapy; 13 patients, negative in the assay, remained in remission, and of 15 relapsed cases 12 were positive. Of 57 patients previously treated by various means for hyperthyroidism, 34 were positive, and they primarily had had relapse after initial treatment, then ablative therapy causing hypothyroidism. Six of 10 patients with euthyroid ophthalmopathy had a positive assay and an abnormal thyrotropin-releasing hormone (TRH) test or thyroid suppression test; the four negative patients had a normal TRH test. Thus measurement of thyroid-stimulating antibody appears effectively to reflect activity of the underlying disturbance in Graves' disease.

Antibodies↗