PubMed Health⌕ Search

Biomedical subjects

K Kula

Publications and source records attributed to K Kula.

At least 37 records · Page 2Linked to original sources
PubMed1995

Stability of the palatal rugae as landmarks for analysis of dental casts.

The aims of this study were to determine if the palatal rugae are stable during normal growth, and whether treatment with either headgear or functional appliances affects the position of the rugae. Initial and 15-month recall dental casts of 94 patients enrolled in a study of early Class II treatment were evaluated. The children had been randomly assigned to one of three groups: control (n = 34), headgear (n = 30), and functional appliance (n = 30). Landmarks on the palatal raphe and palatal rugae were recorded using the Reflex Metrograph. A median palatal plane was constructed using the digitized raphe points as reference. Offsets from this plane to the ruga points and transverse and anteroposterior linear distances between ruga points were obtained for all casts. Transverse offsets and linear distances between medial points of the first rugae and the anteroposterior distances between the medial points of the second and third rugae did not show statistically significant changes in all groups. Significant changes were observed for the lateral points of the rugae, particularly in the headgear group. The medial rugae appear to be suitable anatomic points for the construction of stable reference planes for longitudinal cast analysis.

Analysis of Variance↗
PubMed1994

The effect of topical fluorides on ceramic brackets.

Topical fluorides are frequently prescribed to orthodontic patients to minimize development of initial carious lesions around brackets and bands. However, various topical fluorides are reported to cause surface changes and weight loss of dental materials composed of ceramic elements. Little is known of the effects of these fluorides on ceramic brackets. The purpose of this study was to determine the effects of topical fluorides (0.4% stannous fluoride, 0.5% acidulated phosphate fluoride, and 1.1% sodium fluoride) as compared with water, on the weight and on the surface of the wings and slots of aluminum oxide ceramic brackets. The brackets (n = 10 each treatment agent) were weighed before 6-minute immersions in the treatment agent, rinsed, dried, and reweighed for a total of 10 immersions. The surface appearance of the wings and the slots of the brackets (n = 5 each treatment group) were evaluated with scanning electron microscopy. No statistically significant changes in weight were found among the groups. Surface changes were not observed in either the slots nor the wings of ceramic brackets. Therefore it was concluded that the commercially available topical fluorides when applied as per the regimen in this study to the aluminum oxide ceramic brackets did not cause surface damage or significant weight loss as compared with controls (water).

Acidulated Phosphate Fluoride↗
PubMed1994

[Comparison between the influence of estradiol benzoate, testosterone propionate and human chorionic gonadotropin on initiation of spermatogenesis in the rat].

Newborn male rats were injected daily from the 5th to 15th day of life with: EB in doses of 6.2 or 12.5 or 25.0 micrograms and TP in doses of 1.2 or 2.5 or 5.0 mg (experiment 1), and with hCG (experiment 2) in doses of 2.0 or 4.0 or 8.0 I.U. Animals were sacrificed on the 16th day of life, testes and seminal vesicles were taken and fixed. The function of seminiferous tubules was examined by quantitative analysis of spermatogenesis. EB increased the mean number of germinal cells. TP stimulated differentiation of spermatogonia, but it decreased the number of all germinal cell types. Only the lowest dose of hCG stimulated the mean number of germ cells in the earliest stages of spermatogenesis, hCG used in the higher doses suppresses maturation of seminal tubules and decreases testicular weight.

Animals↗
PubMed1994

[Tamoxifen and spermatogenesis in rats subjected to effects of estradiol].

During 14 subsequent days male Wistar rats received subcutaneously 50 micrograms of EB and different doses of tamoxifen intratesticularly. Action of EB was examined by comparison with the group, which received the solvent for EB only. EB caused the reduction in the mean testis weight, degenerative changes of germinal cells and decrease of blood testosterone level to undetectable values. Tamoxifen did not prevent these changes, but revealed a positive influence on the mean numbers of spermatogonia, spermatocytes and spermatids, including spermatozoa. It indicates that tamoxifen may stimulate the whole spermatogenesis in spite of the inhibition of testosterone production.

Animals↗
PubMed1994

[Influence of intratesticular injections of tamoxifen on spermatogenesis and testosterone secretion in the rat].

Three groups of adult Wistar rats were injected every second day with: 5 or 10 or 20 micrograms of tamoxifen (Tx) to the right testis. Left testis was injected with the same volume of solvent. Control group received the solvent for Tx. Animals were killed after 15 days. Blood samples were taken from heart for testosterone determinations. Both testes were taken for histological examination and quantitative analysis of seminiferous epithelium was performed. Testosterone was analysed with radioimmunoassay method. It was demonstrated that intratesticular supply of Tx caused significant rise in the number of type A spermatogonia and significant increase of testosterone concentration in the blood. It is concluded that Tx influences spermatogenesis in adult rats through stimulation of the earliest steps of gamete formation. Testosterone may or may not mediate this effect.

Animals↗
PubMed1994

[Eosin and water tests and results of conventional semen analysis].

Semen analysis was performed in 95 men and the results of routine examination were correlated with two sperm viability tests: eosin (TE) and water test (TW). Results of TE and TW were expressed as a percent of spermatozoa revealing a functional integrity of the cell membrane. Linear regression analysis was used. Patients were divided into 3 groups: normozoospermia (n = 46), oligozoospermia (n = 27) and profound oligozoospermia (2-4 x 10(6) sperm/ml). No correlations were demonstrated between viability tests and the sperm number. TE and TW significantly positively correlated with each other in all groups. At normo- and oligozoospermia TE and TW positively correlated with the percent of motile spermatozoa. TW did not show such a correlation in men with profound oligozoospermia. It seems that TE and TW can be used alternatively. TW may be of great importance in men with very low sperm count.

Cell Membrane↗
PubMed1992

Dentists, drugs, and decisions: introduction to Part I--Therapeutic drugs.

Numerous dental therapeutic agents or drugs are available over the counter or with prescription for patient use at home or in a professional office. Knowledge of the processes by which these agents are evaluated for safety and efficacy by the FDA and ADA is necessary for dental professionals to make intelligent decisions concerning their use. Several examples of problems with drug/cosmetic evaluations are cited.

American Dental Association↗
PubMed1988

Induction of precocious maturation of spermatogenesis in infant rats by human menopausal gonadotropin and inhibition by simultaneous administration of gonadotropins and testosterone.

This study was undertaken to determine if the initiation of spermatogenesis could be modified by the administration of gonadotropins and sex hormones in infant rats. Five-day-old rats were injected daily between the 5th and 11th days of life with test substances and killed on day 15. Administration of testosterone propionate (TP; 2.5 mg daily), human menopausal gonadotropin (hMG; 7.5 IU daily), or coadministration of both of these substances (TP + hMG) or administration of estradiol benzoate (15 micrograms daily) caused quantitative changes in premeiotic spermatogenesis, as measured by the mean cell counts per tubule cross-section. hMG caused an increased yield of type A1 spermatogonia (SgA1) from undifferentiated type A spermatogonia (UnA) and increased the yield of type B spermatogonia from SgA1. TP was not effective in stimulating first premeiotic spermatogenesis, and in contrast to hMG, it had a negative influence on the numbers of UnA and SgA1 and on the volume of Sertoli cell nucleus. Administration of TP + hMG or estradiol benzoate resulted in a significant increase in the numbers of UnA and SgA1, but inhibited cell differentiation. TP + hMG significantly reduced the rate of premeiotic spermatogenesis. The results demonstrate that precocious numerical stabilization of premeiotic spermatogenesis can be achieved by the application of hMG. TP applied alone was able to induce peripheral androgenic effects (seminal vesicle weight) 100% greater than those produced by administration of hMG, but was not able to stimulate seminal tubule function. TP applied together with hMG produced inhibition of spermatogenesis. This effect might be due to the inhibition of Sertoli cell function by the direct influence of testosterone. In contrast to testosterone, estradiol may play a stimulatory role in the multiplication of the reserve stem cells of the first spermatogenesis of the rat.

Animals↗
PubMed1987

Pharmacological evaluation of an intra-oral fluoride-releasing device in adolescents.

The purpose of this study was to quantify fluoride (F) concentrations in body fluids of adolescents wearing two intra-oral fluoride-releasing devices (IFRDs) designed to release 0.10 mg F/day. Fluoride concentrations were determined potentiometrically. No significant increases occurred in urine or serum F concentrations during the 26-week device phase. Elevated salivary F concentrations were maintained throughout the device phase when broken or depleted IFRDs were replaced. However, salivary F concentrations returned to pre-device phase values by 26 weeks when the original IFRDs were maintained. These findings suggest that IFRDs can significantly elevate salivary F concentrations of adolescents without significant elevations in systemic F concentrations.

Adolescent↗
PubMed1986

Changes in gonadotropin regulation in both behavioral and phenotypic disturbances of sexual differentiation in men.

Determinations of gonadotropins and testosterone were performed in 22 men with hypospadias (H), seven male-to-female transsexuals (T) and in 16 normal men (N), all of similar age. The response of serum FSH and LH to GnRH was determined in six subjects in each group. Oligospermia was found in five of 13 patients with H. All patients with transsexualism revealed normospermia. Both the patients with H and with T had significantly higher mean serum concentrations of LH than the normals (H: 16.96 +/- 13.83 mIU/ml; T: 15.30 +/- 6.50 mIU/ml; vs 5.73 +/- 3.66 mIU/ml in N). Also, an exaggerated response of LH to GnRH was found in both H and T. No negative correlations were demonstrated between serum LH and testosterone in either the H or the T. Rather, higher mean serum LH occurred together with higher mean serum testosterone in severe H. A significant elevation of basal serum FSH was found in H (H: 7.24 +/- 2.14 mIU/ml vs N: 4.84 +/- 1.65 mIU/ml), which might be related to underlying gonadal injury. No increase of serum basal FSH concentration was found in T patients, but the FSH response to GnRH was higher than in N. It is concluded that hypospadias, a phenotypic disturbance of sexual differentiation, represents a less-specific change in the gonadotropin regulation, while male transsexualism reveals hypergonadotropism with a specifically increased evocability of gonadotropins not coexisting with signs of gonadal injury.

Adolescent↗
PubMed1986

A nonspecific disturbance of the gonadostat in women with transsexualism and isolated hypergonadotropism in the male-to-female disturbance of gender identity.

Principal parameters of gonadostat function were determined in 15 female-to-male (F-M) and 7 male-to-female (M-F) transsexual patients (T), all homosexuals. The data were compared with normal heterosexual controls of the respective sex. Anamnesis revealed prolongation of the menstrual cycles in F-M patients, mainly in those taking previously medication with depot-testosterone. However, also in patients with no previous medication the basal body temperature chart revealed anovulatory cycles (all 4 examined patients). In 8 of 9 patients (82.2%) with no previous medication an elevation of serum testosterone was found (63-600 ng/dl). No disturbances in gonadal functions were found in M-F group (semen analysis), serum testosterone was normal (328-710 ng/dl) except 1 case with reduced testosterone level (200 ng/ml). Both women and men with transsexualism revealed significantly higher mean basal serum concentration of LH in comparisons to controls (F-M: 23.14 +/- 16.16 vs 7.56 +/- 4.23; M-F 15.30 +/- 6.49 vs 5.75 +/- 3.66). No changes in basal serum FSH concentration were present. GnRH test (100 micrograms i.v.) revealed decreased evocability of LH in woman with T and exaggerated LH response in men with T. FSH hyperresponse to GnRH was nonsignificant in F-M and significant in M-F T. It is concluded that F-M transsexualism is associated with nonspecific disturbances of gonadostat since hypergonadotropism coexists with the signs of impaired gonadal function. In M-F T and isolated hypergonadotropism coexisted with specific, increased sensitivity of the pituitary to GnRH.

Adolescent↗