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Biomedical subjects

G Zajicek

Publications and source records attributed to G Zajicek.

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

Streaming of labelled cells in the conjunctival epithelium.

This study examines epithelial cell streaming and turnover in normal rat bulbar conjunctiva. Twenty seven male adult random-bred Hebrew rats weighing between 250-300 g, were injected i.p. with [3H]-thymidine. Three rats were killed at various times, thereafter from 1 h to 28 days. The enucleated eyes were fixed in formalin, cut into 5 microns thick sections, dipped into liquid emulsion, exposed for three weeks and stained with haematoxylin and eosin. Conjunctival epithelium was scanned from the limbus and outward, using an ocular micrometer grid with 10 x 10 divisions. In each consecutive field the grid was positioned along the basement membrane which was defined as the x-axis. The y-axis extended from the basement membrane outward. The x, y coordinate of each nucleus with three grains or more and its grain content were recorded along the entire epithelium. Conjunctival epithelium is divided into two cell kinetic compartments: a progenitor (P), along the basal and supra basal layer, in which cells proliferate, and a non proliferating Q-compartment, in the layers above. One hour after labelling most of the labelled cells were in the basal and supra basal layers. From then onward labelled cells streamed along both axes. Their x-velocity was 10.5 +/- 2.4 microns/day and the y-velocity 9.3 +/- 5.4 microns/day. Cells are eliminated at the epithelial surface which is the outer Q-compartment boundary. Basal cell turnover was estimated from grain count dilution curves. The time it takes for the grains in a cell to reach half of their initial value was 8.3 days. It is closely related to the cell's generation time. The present study demonstrates that conjunctival epithelium in the rat streams along two axes, x, and y: 1. The x-axis extends along the basal layer, from the limbus and outward. 2. The y-axis extends from the basal layer into the layers above it. Cells first stream along the x-direction and then turn y-ward. Since cells are ultimately exfoliated from the conjunctival surface, and since the conjunctiva maintains steady state, we propose that stem cells located in the limbus generate transitional cells that stream along the two axes. Macroscopically the limbus is circular, and the stem cells are situated around the cornea. Each stem cell and its streaming progeny can be viewed as a conjunctival epithelial unit. We propose that conjunctival and corneal epithelium, are the descendants of an uncommitted stem cell that generates two differentiation pathways, a corneal and a conjunctival.

Animals↗
PubMed1995

Sex ratio in triplets.

Since the introduction of different ovulation induction regimens the incidence of triplet pregnancies increased from a spontaneous rate of about 1:10,000 to the frequency of nearly 1:1000. Sex ratio of trigemini and male/female proportion of the three newborns within the same triplet set is the amazing issue that we attempted to elucidate in the present study. Data on 36 women with triplet pregnancies delivered in our hospital and information regarding 2717 triplet pregnancies reported by 16 relevant papers were included in this study. 36 women delivered 63 (58%) male and 45 (42%) female babies. Triplet sets of same gender comprised 33% of all trigemini. Sex ratios (male/female) for the spontaneous, menotropin and clomiphene group were 2.00, 1.57 and 0.94 respectively. Homogenous male/female set ratio was 5.0, 2.0 and 0.5 in menotropin, spontaneous and clomiphene groups respectively. As the percentage of ovulation induction triplet pregnancies increased constantly from 0% to 100%, a decline in the fraction of homogenous gender triplet sets was observed--from 73% to 23%. It may be concluded that sex ratio in triplet newborns is divergent according to different publications with most of the authors reporting a male/female ratio of less than 1.00. Ovulation induction results in a lower proportion of homogenous sex triplets sets. Superovulation by menotropins cause a higher percentage of male triplet newborns when compared to ovulation induction by clomiphene.

Clomiphene↗
PubMed1994

A comparison between a standard and reduced dose of D-Trp-6-luteinizing hormone-releasing hormone administered after pituitary suppression for in-vitro fertilization.

A randomized prospective study was undertaken to compare low and standard luteinizing hormone-releasing hormone agonist (LHRHa) dosage used in combination with gonadotrophins in ovarian stimulation for in-vitro fertilization (IVF). A total of 42 ovulatory patients with mechanical infertility were administered 0.5 mg/day LHRHa (Decapeptyl) from day 21 of their cycles for 14 days. Following down-regulation, patients were randomly allocated to continue with the same dose of LHRHa (22 patients, group A) or to receive a lower dose of 0.1 mg/day LHRHa (20 patients, group B) during folliculogenesis. Luteal phase was supported by daily i.m. progesterone (50 mg) injections and human chorionic gonadotrophin (HCG; 1500 IU) every 4 days. Ovarian response, human menopausal gonadotrophin (HMG) dosage used for induction of ovulation, evidence of premature luteinization, and clinical and laboratory IVF outcome, were compared between groups A and B. The two groups were comparable in respect of: age (32.6 +/- 0.7 and 33.0 +/- 0.9 years), HMG dosage (33.0 +/- 1.6 and 36.0 +/- 2.5 ampoules), day of HCG (11.2 +/- 0.3 and 12.2 +/- 0.4), oocytes/patient (13.3 +/- 1.0 and 12.9 +/- 1.3), fertilization rate (68.5 and 65.2%), cleavage rate (95% for both), pregnancy/embryo transfer (32 and 35%) and implantation rate (10.8 and 10.5%), for groups A and B respectively. There was no evidence of premature luteinization or luteolysis in either group. It was concluded that lowering the dose of LHRHa to 0.1 mg/day during folliculogenesis had no adverse effect on ovarian response or clinical results. However, it had no advantage in reducing the HMG dose used for ovulation induction.

Adult↗
PubMed1993

Kinetic analysis of epithelial cell migration in the colon on a massively parallel processor (CM-2).

A cell kinetic model of proliferating tissues and its implementation on the massively parallel computer, Connection Machine Model 2 (CM-2), is presented. The model is applicable to all proliferating tissues of the organism and is illustrated on the crypt-villus unit (CU) of the gastrointestinal mucosa. The crypt unit consists of two compartments, a progenitor (P) in which cells proliferate, and a proliferative quiescent (Q) compartment, in which cells are incapable of synthesizing DNA and therefore do not divide. Cells are formed in P, enter Q, traverse it, and die at its outer boundary. The healthy CU maintains a steady state; cell proliferation is controlled by cell elimination. The crypt cylinder is mapped onto a two-dimensional CM-2 matrix such that each processor represents a cell in the unit. The interprocessor links serve as proliferation controls. Using cell counts, the frequency of P cells in each cell location along the crypt column was estimated and various columnar kinetic parameters were calculated. The kinetic analysis shows that cell migration occurs along the crypt column in the direction of the colonic lumen at a velocity averaging 0.244 cell locations per hour. In order to compare model results with experimental kinetic studies, the model was used to stimulate a labeling experiment. The results are in agreement with published kinetic experiments that were done on a normal CU. The model allows three-dimensional visualization of the spatial and temporal events within the crypt.

Algorithms↗
PubMed1993

Conception rate after in vitro fertilization in patients who conceived in a previous cycle.

OBJECTIVE: To evaluate whether a previously successful in vitro fertilization and embryo transfer (IVF-ET) cycle is a favorable prognostic factor for a subsequent cycle. DESIGN: A retrospective comparison between current IVF patients who have previously conceived in an IVF versus natural cycle. SETTING: The IVF unit of a university hospital. PATIENTS: Group A consisted of 51 patients (70 cycles of IVF-ET) who previously conceived in an IVF-ET cycle, and group B included 141 patients (201 cycles of IVF-ET) who previously conceived in a natural cycle. All couples with male factor infertility were excluded. Ovulation induction protocol was identical for both groups and consisted of gonadotropin-releasing hormone agonist pretreatment followed by gonadotropin stimulation. MAIN OUTCOME MEASURES: Pregnancy rate per ET, cumulative pregnancy rate, and livebirth rate in both groups. RESULTS: The following parameters were comparable for both groups: age, menotropin dosage required for an adequate stimulation, ovarian response, mean number of oocytes retrieved per cycle, fertilization and cleavage rates, and the mean number of embryo transferred. Group A attained a significantly higher pregnancy rate (PR) than group B (31.4% versus 19.4%). Group A also achieved a significantly higher livebirth rate (22.9% versus 11.4%) than group B. Similarly, the cumulative PR curves and the cumulative livebirth rate curves for three consecutive IVF-ET cycles differed significantly between the two groups. CONCLUSION: A previous successful IVF cycle is a positive prognostic factor for a repeated IVF attempt. This effect could be because of either an improved endometrial response or a better embryo quality. It may be that this patient population is relatively immune to the known untoward effects of ovulation induction on endometrial development and, therefore, may represent a potential clinical model that can be used to further identify the factors influencing uterine receptivity after ovulation induction.

Adult↗
PubMed1993

Elective suture of uterine cervix in triplets.

The incidence of triplet pregnancies has increased several times due to the widespread use of ovulation induction agents. Premature delivery is the main complication of triplet gestations. In twin conceptions it was shown definitely that elective cervical suture does not prolong these pregnancies. However, in higher order multifetal gestations the uterus is extremely overdistended and the application of cerclage is equivocal. This work intended to assess the value of elective cervical sutures in prolonging triplet pregnancies. Twelve of 35 women with triplet conceptions hospitalized at our high-risk pregnancy unit underwent an elective cerclage at 12 to 14 weeks and 23 women served as control subjects. None of them had any history or physical findings of cervical incompetence prior to the procedure. The gestational age (weeks) at delivery was 33.0 +/- 5.1 and 34.7 +/- 2.8 (mean +/- SD) for the sutured and noncerclage groups, respectively. The birthweight (grams) of the neonates was 1833.0 +/- 524.5 and 1884 +/- 455.5 (mean +/- SD) for the cerclage and nonsutured women, respectively. It seems that triplet gestations as such do not benefit from an elective cervical suture.

Birth Weight↗
PubMed1993

Discordancy in triplets.

Discordancy in twins is generally described as a weight difference between the fetuses of 15 to 25% and its prevalence in normal twin gestations is estimated at 15 to 29%. The present study was performed in order to determine the frequency of discordant newborns in uncomplicated triplet gestations. One hundred and fourteen normal triplet newborns were delivered during a period of 11 years. Their birthweight ranged from 493 to 2533 gm, with a mean of 1894.2 +/- 468.5 gm (+/- sd). In 58% of these 38 sets of triplets the difference in weight between the largest and smallest newborn was more than 15%. About a quarter of the newborns had a greater than 25% dissimilarity in their birthweights. There was no substantial fetal-fetal transfusion or difference in the Apgar scores between the discordant fetuses. It may be concluded that triplet newborns have a rate of discordancy double that of twins. Discordance per se does not necessarily mark an underlying complication of pregnancy or a bad perinatal outcome.

Birth Weight↗
PubMed1993

Sonographic growth curves of triplet conceptions.

The diagnosis of inappropriate intrauterine fetal growth in triplet pregnancies requires normal standard sonographically determined growth curves. The aim of the present study was to establish such nomograms. The biparietal diameter (BPD), femur length, head and abdominal circumferences (HC, AC) were once in 3 weeks sonographically evaluated in 108 normal triplet fetuses. The resulting growth curves were compared with those of normal singleton fetuses. The data showed that, compared with singletons, the mean triplet fetal BPD progressively lags to a maximum of 2 1/2 weeks as pregnancy continuous from the 25th to the 36th gestational week. Similarly, mean femur length of triplet fetuses gradually shortfalls to the greatest of 2 weeks as gestation advances from the 25th to the 36th week. HC to AC ratio of the triplet fetuses does not differ from the singletons curve. It may be concluded that a normal fetal growth curve in triplet pregnancies demonstrates a 1- to 3-week delay compared with singleton gestations.

Embryonic and Fetal Development↗
PubMed1993

A comparison of sonographic growth curves of triplet and twin fetuses.

Sonographic growth curves of 47 normal triplet pregnancies were compared with those of 71 uncomplicated twin gestations. Starting from the 25th week, the biparietal diameter in triplets was found to lag progressively compared with that of twins, reaching a mean difference of 2 weeks at 36 weeks gestation. Similarly, a significant difference was found between the femur length and head to abdomen circumference ratio growth curves of triplets and twins. It is concluded that as pregnancy continues from the 25th to the 36th gestational week, there is a significant delay in the growth patterns of normal triplet pregnancies compared with twin gestations.

Age Factors↗
PubMed1992

Cell kinetics of lamina propria fibroblasts in normal adult hamster bronchus.

Forty-nine 12-week-old male Syrian golden hamsters (Mesocricetus auratus), weighting 108 to 128 g, were injected i.p. with [3H]-thymidine (3HTdR 2 microCi/g body wt). Animals were divided into 7 weight-matched groups and were killed at 1 hour (day zero) and 1, 2, 3, 4, 7, and 14 days after thymidine injection. Lungs were fixed by vascular perfusion of 4% formalin/1% glutaraldehyde in 0.2 M cacodylate buffer at pH 7.4, cut at 2 microns, dipped in Kodak NTB3 or NTB2 nuclear emulsion, exposed for 2 weeks, developed and stained. In each airway cross-section, total epithelial and fibroblast counts and labeled cell count were estimated. A cell was considered labeled when 3 or more silver grains appeared on its nucleus. The background grain count was less than 1 grain per nucleus. Mean epithelial and fibroblast cell density in a 100 microns segment were respectively 14.8 +/- 0.1 and 6.6 +/- 0.1 cells (the second number is one standard error of the mean). One hour after labeling, their respective labeling indices (L.I.) were 0.13 +/- 0.02 and 1.24 +/- 0.1. On day 1, their L.I. doubled and then returned to the initial value. One hour after labeling, epithelial and fibroblast mean grain counts did not differ significantly. They were respectively 20.6 + 1, and 15.8 +/- 2. Because grain count intensity is closely related to DNA synthetic time, it seems plausible that epithelial and fibroblast synthetic times do not differ much. Cell turnover and cell cycle times were estimated from grain count dilution curves.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Bromobenzene accelerates hepatocyte streaming in rats.

Sixty male adult rats weighing between 250 and 300 g were divided in two equal experimental groups. The first experiment was designed to evaluate hepatocyte streaming. Animals were injected with 0.5 microCi [3H]thymidine and 1 hour later received one intraperitoneal injection of bromobenzene (3.8 mmol/kg, dissolved in corn oil). The animals were then killed in groups of five at 1 hour and 2, 4, 7, 14, and 30 days. The aim of the second experiment was to evaluate labeling index changes with time. Animals received one intraperitoneal injection of bromobenzene and were killed in groups of five at 1, 2, 3, 4, 7, and 14 days. They received [3H]thymidine 1 hour before killing. Bromobenzene induced a necrosis in the third acinus zone that disappeared within a week. On day 0 the labeling index of hepatocytes and littoral cells was 0.3% +/- 0.04% and 0.4% +/- 0.05%, respectively. On the second day, it reached 14.6% +/- 2.6% and 10.1% +/- 3.1% and returned to its initial value after 1 week. Dead cells in the third zone were replaced by inflowing cells from the intact zones. Hepatocytes and littoral cells streamed at the same velocity of 6 +/- 0.5 micron/day, faster than in untreated animals with velocity of 3.2 microns/day. Parenchyma and stroma responded to injury in a coordinated fashion. From the functional point of view, hepatocytes and littoral cells operate as a unit that is called proliferon. The maximal proliferon life span was 57 days after bromobenzene treatment and 108 days in controls.

Animals↗
PubMed1992

The state of leukocyte adhesiveness/aggregation in the peripheral blood is more sensitive than the white blood cell count for the detection of acute mental stress.

We determined the state of the leukocyte adhesiveness/aggregation in the peripheral blood by using a simple slide test and found it to be more sensitive than the white blood cell count for the detection of acute mental stress. Included were 71 controls, 64 young athletes examined just before their exercise, 14 volunteers who were examined 10-20 min before engagement in rappelling while an additional group of 20 were examined just before the act as they were facing an abyss from the top of a cliff. The state of leukocyte adhesiveness/aggregation correlated significantly (p less than 0.0005) only with the increasing strain assumed to occur from the first to the fourth group. The state of leukocyte adhesiveness/aggregation was 3.3 x more sensitive than white blood cell count in both rappelling groups and 5 x more sensitive than white blood cell count when evaluated in those examined at the last minute. We concluded that the state of leukocyte adhesiveness/aggregation is a reliable marker of acute mental stress.

Adolescent↗
PubMed1992

CA-125 is present in significant concentrations in periovulatory follicles of in vitro fertilization patients.

OBJECTIVE: To evaluate the presence of CA-125 in follicular fluid (FF) and its possible correlation to FF estradiol (E2), progesterone (P) and testosterone (T) and in vitro fertilization and embryo transfer (IVF-ET) outcome. DESIGN: Twenty-eight patients undergoing IVF-ET were randomly chosen and 123 FF were sampled. SETTING: Clinical IVF-ET program and immunology laboratory for tumor diagnosis in a university tertiary care center. PATIENTS: Pure tubal factor patients treated by midluteal (long) gonadotropin-releasing hormone agonist protocol coupled with follicular phase human menopausal gonadotropin. INTERVENTIONS: Transvaginal follicular aspiration followed 48 hours later by ET. MAIN OUTCOME MEASURES: The 28 treatment cycles resulted in six gestations including five take-home infants. The mean levels (+/- SD) were 30.1 +/- 66.0 U/ML for CA-125, 28.5 +/- 58.1 ng/ML for E2, 2,360.5 +/- 2,846.3 ng/ML for P, and 7.22 +/- 7.08 ng/ML for T. The FF CA-125 levels were found to be widely divergent in different follicles of the same patient. There was no significant correlation between FF CA-125 and E2, P, T, oocyte fertilization, embryo quality, and pregnancy rates. CONCLUSIONS: CA-125 exists in significant amounts in FF of periovulatory follicles of IVF-ET patients. Intrafollicular CA-125 secretion is neither interrelated to follicular steroidogenesis nor is correlated to the outcome of IVF-ET.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1992

Time dimension in histopathology.

In the liver acinus hepatocytes and littoral cells stream from the portal tract toward the terminal hepatic vein. Their average displacement trajectory was denominated as tissue radius. Since cells advance on the tissue radius in one direction, the farther a cell is the older it is, and cell age may be estimated from its position. This property is regarded as time dimension of a tissue. Since distance may be estimated by image cytometry, age determination may be incorporated in the image cytometer software. Distance may be expressed in two types of units: 1. metric e.g. microns, and 2. cell location or the number of cells separating a given cell from tissue origin. Cell age may also be expressed by two units: chronological and biological. Chronological age may be derived from the cell's displacement velocity. A hepatocyte advances daily 2 microns so that a cell at 100 microns distance is 50 days old. Biological age is defined as the cell's location on the radius. Cell location may serve as biological age unit since cells ranked according to their location are also ranked by their ages. The average acinus radius is 22 location long so that in biological age units, maximal hepatocyte life span is 22 locations. One may even say that a cell at location 5 is 2 biological units older than a cell at location 1. In order to estimate chronological age the cell has to be followed for a period of time, while biological age may be read off once from the section. There is yet another advantage for utilizing cell location as unit.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Division↗