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Biomedical subjects

Z Schwartz

Publications and source records attributed to Z Schwartz.

At least 235 records · Page 13Linked to original sources
PubMed1988

The effects of vitamin D metabolites on phospholipase A2 activity of growth zone and resting zone cartilage cells in vitro.

Third passage confluent cultures of cartilage cells, initially derived from the growth zone (GC) and resting zone (RC) of rat costochondral cartilage, were incubated with either 10(-11)-10(-8) M 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] or 10(-9)-10(-6) M 24,25-(OH)2D3. Plasma membranes and extracellular matrix vesicles were isolated, and specific activities of phospholipase A2 and alkaline phosphatase were determined. The results demonstrate that the response to hormone is both cell and membrane specific. 1,25-(OH)2D3 produces an increase in GC matrix vesicle alkaline phosphatase and phospholipase A2 specific activities at 10(-9) and 10(-8) M, but has no effect on these enzyme activities in RC membranes. RC cultured in 24,25-(OH)2D3 exhibit increased matrix vesicle alkaline phosphatase but decreased phospholipase A2 activities at 10(-7) and 10(-6) M hormone. No effect on the RC plasma membrane enzymes or on GC plasma membrane or matrix vesicle enzymes was observed. The data suggest that changes in membrane fluidity due to phospholipase A2 activity may play a role in regulating alkaline phosphatase activity in response to vitamin D metabolites and that this regulation in GC and RC may proceed by different mechanisms.

24,25-Dihydroxyvitamin D 3↗
PubMed1988

The effects of vitamin D metabolites on the plasma and matrix vesicle membranes of growth and resting cartilage cells in vitro.

This study compares the effects of vitamins 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] and 24,25-(OH)2D3 on populations of chondrocytes at different developmental stages. Confluent third passage chondrocytes derived from the resting zone and adjacent growth region of rat costochondral cartilage were cultured in Dulbecco's Modified Eagle's Medium containing 10% fetal bovine serum and increasing concentrations of hormone. After determination of cell number, matrix vesicles and plasma membranes were isolated by differential centrifugation. The effects of hormone on alkaline phosphatase, 5'-nucleotidase, ouabain-sensitive Na+/K+-ATPase, and phospholipid composition were dependent on vitamin D metabolite and were cell specific. Growth cartilage chondrocytes responded primarily to 1,25-(OH)2D3, whereas resting zone cells responded primarily to 24,25-(OH)2D3. 1,25-(OH)2D3 inhibited growth cartilage cell number at pharmacological concentrations and had no effect on resting cartilage cell number. In contrast, 24,25-(OH)2D3 appeared to stimulate resting cartilage cell number at physiological concentrations and inhibit these cells at pharmacological doses, but had no effect on growth cartilage chondrocytes. These data were supported by [3H]thymidine incorporation studies. 1,25-(OH)2D3 stimulated alkaline phosphatase, 5'-nucleotidase activity, and Na+/K+-ATPase activity in the matrix vesicles of growth cartilage cells. 1,25-(OH)2D3 also stimulated Na+/K+-ATPase activity in the matrix vesicles and plasma membranes of resting zone cells. Incubation with 24,25-(OH)2D3 stimulated alkaline phosphatase, 5'-nucleotidase, and Na+/K+-ATPase in the matrix vesicles produced by resting zone cells. In addition, 24,25-(OH)2D3 stimulated Na+/K+-ATPase activity in the plasma membranes of resting zone cells as well as in both matrix vesicles and plasma membranes of growth cartilage cells.

24,25-Dihydroxyvitamin D 3↗
PubMed1988

Direct effects of 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 on growth zone and resting zone chondrocyte membrane alkaline phosphatase and phospholipase-A2 specific activities.

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] and 24,25-(OH)2D3 differentially affect the specific activity of alkaline phosphatase (ALPase) and phospholipase-A2 (PLA2) of plasma membranes and extracellular matrix vesicles produced by costochondral reserve zone and growth zone cartilage chondrocytes in culture. In the present study, growth zone and cartilage and reserve zone matrix vesicles and plasma membranes were isolated from confluent chondrocyte cultures and incubated with hormone for 3 and 24 h in vitro. Addition of 1,25-(OH)2D3 to GC matrix vesicles and plasma membranes resulted in dose-dependent increases in ALPase and PLA2 specific activities in both membrane fractions. Addition of 24,25-(OH)2D3 to RC membrane fractions stimulated matrix vesicle ALPase at 10(-7) and 10(-8) M and plasma membrane ALPase at 10(-8) M only. However, 24,25-(OH)2D3 inhibited matrix vesicle and plasma membrane PLA2 activity. The effects of the vitamin D metabolites were noticed after both 3 and 24 h. Neither hormone metabolite had any effect on these enzymes in membrane fractions from cultures of neonatal rat muscle mesenchymal cells, which do not calcify their matrix in vivo. These data suggest that 1,25-(OH)2D3 and 24,25-(OH)2D3 can directly affect chondrocyte membrane enzymes without genomic influence or protein synthesis and that membrane response depends on the stage of chondrocyte differentiation. Changes in PLA2 activity may change membrane fluidity and may be a mechanism by which the hormones affect cell membranes.

24,25-Dihydroxyvitamin D 3↗
PubMed1988

The relationship between extracellular matrix vesicles and the calcifying front on the 21st day after injury to rat tibial bone.

The relationship between extracellular matrix vesicles and the calcifying fronts was examined by studying vesicular diameters and types. Transmission electron microscopy combined with computerized morphometry three weeks after injury to the tibial bone in rats was used. The different vesicle types were defined as: (1) vesicles with electron lucent contents referred to as empty; (2) vesicles with amorphous electron opaque contents, called amorphic; (3) vesicles containing crystalline depositions, called crystalline; and (4) vesicles containing crystalline structures with ruptured membranes, referred to as ruptured. The diameters of most vesicles ranged between 0.07 and 0.17 micron. More than 95% of the vesicles were located less than 2 micron from the calcified front. The vesicles were distributed among the categories as follows: empty, 9.6%; amorphic, 19.3%; crystal, 39.2%; and ruptured, 31.9%, respectively. The diameters of the crystalline and ruptured vesicles were significantly larger than those of the empty and amorphic types. The ruptured type had the largest diameters. The sequence of distances from the calcified front was recorded as follows: ruptured, crystalline, amorphic, and empty, with the ruptured and crystalline types being the closest to the front. This study supports the accepted theory on matrix vesicle mineralization. The cell is responsible for secretion of empty vesicles that accumulate amorphous Ca and Pi to form a hydroxyapatite crystal. This is followed by rupture of the vesicular membrane. The propagation of the process is accompanied by an increase in the vesicular diameter and its approximation to the calcifying front.

Animals↗
PubMed1987

Changes in the distribution of extracellular matrix vesicles during healing of rat tibial bone (computerized morphometry and electron microscopy).

A study of the distribution of extracellular matrix vesicles during the first 3 weeks of healing of adult rat tibial bone was performed by transmission electron microscopy in combination with computerized morphometry. Bone injury comprised removal of the marrow followed by regeneration of the tissue via a phase of primary mineralization. A total number of 39,498 vesicles were traced on electron micrographs and sorted according to their diameters, distance from the calcified front and types. The different vesicular types were defined as follows: (a) vesicles with electron lucent contents, i.e. "empty", (b) vesicles with amorphous electron opaque contents, i.e. "amorphic", (c) vesicles containing crystalline depositions, i.e. "crystal", and (d) vesicles containing crystalline structures with ruptured membranes i.e. "rupture". The vesicles were studied on the days 3, 6, 14 and 21 after bone injury. Most of the vesicles were concentrated between diameters of 0.07 and 0.17 micron. Most of the vesicles were found in a distance less than 3 microns from the calcified front. The sequence of changes of distances from the calcified front and of the vesicular diameters were recorded as follows: "rupture", "crystal", "amorphic" and "empty", the "rupture" type being the closet to the front and of the largest diameter in each day. The results of the present study confirm the accepted hypothesis on calcification via extracellular matrix vesicles. It is thought that the cell secretes "empty" vesicles that accumulate Ca and Pi forming amorphous calcium phosphate that is then converted to hydroxyapatite. This is followed by rupture of the vesicular membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Ultrastructural tissue morphometry of the distribution of extracellular matrix vesicles in remodeling rat tibial bone six days after injury.

A study of the distribution of extracellular matrix vesicles on the 6th day of bone healing was performed by methods of transmission electron microscopy combined with computerized morphometry. The vesicles were detected on the electron micrographs and grouped according to their diameters, distance from the calcified front and type. The different types were selected as follows: vesicles with electron-lucent contents, i.e., 'empty'; vesicles with amorphous electron-opaque contents, i.e., 'amorphous'; vesicles containing crystalline depositions, i.e., 'crystal', and vesicles containing crystalline structures with ruptured membranes, i.e., 'rupture'. Most of the vesicles were concentrated between diameters of 0.02 and 0.22 microns. Most of the vesicles were found within a distance of less than 3 micron from the calcified front. The vesicles were distributed according to their types: 'empty', 'amorphous', 'crystal' and 'rupture' in 14, 39, 34 and 13%, respectively. The diameters of the 'crystal' and 'rupture' vesicles were significantly larger than those of the 'empty' and 'amorphous' types. The sequence of distances from the calcified front was recorded as follows: 'rupture', 'crystal', 'amorphous' and 'empty', the 'rupture' type being the closest to the front. The results of the present study confirm the accepted hypothesis on calcification via extracellular matrix vesicles. It is thought that the cell secretes 'empty' vesicles that accumulate amorphous Ca and P to form a hydroxy-apatite crystal. This is followed by rupture of the vesicular membrane. The propagation of the process is accompanied by increase in the vesicular diameter and its approximation to the calcifying front.

Animals↗
PubMed1987

Extracellular matrix vesicle distribution in primary mineralization two weeks after injury to rat tibial bone (ultrastructural tissue morphometry).

Primary mineralization on the 14th day of bone healing served as a model to study the distribution of extracellular matrix vesicles by means of transmission electron microscopy combined with computerized morphometry. Vesicles were traced on electron micrographs and classified according to diameter, distance from the calcified front, and type. The different types were determined as follows: electron-lucent vesicles ("empty"), vesicles with amorphous contents ("amorphic"), vesicles containing crystalline depositions ("crystal"), and vesicles with crystals and ruptured membranes ("rupture"). The majority of the vesicles measured between 0.02 and 0.07 micron and were located at a distance of less than 3 micron from the calcified front. They were distributed according to "empty", "amorphic", "crystal" and "rupture" type in concentrations of 10%, 31%, 51% and 8%, respectively. The diameters of the "rupture" vesicles were significantly larger than those of the "empty" and "amorphic" types. The sequence of their location, starting at the calcified front, ran as follows: "rupture", "crystal", "amorphic" and "empty", with the "rupture" type proximate to the front. According to the working hypothesis on calcification via extracellular matrix vesicles, it is thought that the "empty" vesicles are secreted by the cell and that subsequently amorphous Ca and Pi accumulate intravesicularly to form a hydroxyapatite crystal which, in turn, brings about rupture of the vesicle's membrane. The results of the present study support this theory and, additionally, show that the maturation process is accompanied by an increase of the vesicular diameter and by its approximation to the calcifying front.

Animals↗
PubMed1986

Second primary genital malignancies associated with endometrial cancer.

Epidemiological data on Israeli patients with second primary genital malignancies associated with endometrial cancer is presented. During the 7 years of study, 29 (2.9%) of 1,007 patients with endometrial cancer had additional primary malignancy involving the genital organs. Of these, there were 25 (2.5%) ovarian and 4 (0.4%) cervical malignancies. The occurrence of a second malignancy was related to ethnic origin. The ratio of European/American to Asian/African Jewish descendants was 8.7 to 1. A significantly greater than expected incidence of ovarian and cervical malignancy was detected in the endometrial cancer patient (P less than 0.0001). The prognosis was mainly influenced by the clinical staging of disease at the time of diagnosis. Recognition of the fact that second primary cancers occur at a higher than expected frequency in patients with endometrial cancer, offers an opportunity for their early detection.

Age Factors↗
PubMed1986

Enzyme activities in the androgenized rat uterus refractory to oestrogenic stimulation.

Uterine enzymes involved in the intermediary metabolism of glucose have been measured in the androgenized rat in which there is evidence of diminution of the oestrogenic responses despite raised glycogen and glucose typical of maximal oestrogenic stimulation. Phosphofructokinase and isocitrate dehydrogenase (NADP, cytosolic) activities were significantly decreased in the androgenized rat and were elevated following treatment with natural progesterone and synthetic progestins which partially reverse the uterine abnormalities of the androgenized rat. Mitochondrial protein was decreased in the uterus of the androgenized rat but there was an apparent sparing effect on isocitrate (NAD) and malate (NAD) dehydrogenase. The data suggest that selective effects on specific enzymes involved in intermediary metabolism are a feature of the refractory state associated with constant oestrogenic stimulation. The possible cellular mechanisms underlying these effects are discussed.

Animals↗
PubMed1986

The development of fetal mice long bones in vitro: an assay of bone modeling.

This study was carried out to develop an in vitro system for the analysis of bone modeling (coincidentally occurring bone growth, formation, mineralization, and resorption) as is seen during bone development. The fetuses of pregnant mice previously labeled with 45Ca were removed on Days 15, 16, and 17 of gestation. The radii and ulnae were dissected free and cultured for up to 6 days in a chemically defined medium (BGJ) supplemented with fetal calf serum or human serum albumin and 150 micrograms/ml vitamin C. The change in bone length over the culture period was measured as were the changes in calcium and phosphorus content, the hydroxyproline: protein ratio, and the percent 45Ca released into the medium. The effect of insulin and parathyroid extract on the system was also examined. The results indicate that cultures of 16-day-old fetal bones provided the most suitable model. During culture there was a continuous increase in bone length as well as calcium and phosphorus content in the ratio of 2:1, a significant increase in the hydroxyproline content, and a continuous release of 45Ca into the medium. Parathyroid extract caused a dose-dependent inhibition of both growth in diaphyseal length and calcium and phosphorus uptake with an increase in 45Ca release into the medium. Insulin at 10(-9) M and 10(-10) M resulted in a significant increase in diaphyseal length and calcium and phosphorus uptake without affecting 45Ca release. These results indicate that the assay described is suitable for the study of bone modeling, providing a means to measure bone growth, formation, calcification, and resorption. The direct effect of various factors on bone modeling can also be measured.

Animals↗
PubMed1986

Constant ovulation on the side of an occluded tube treated with human menopausal gonadotropin.

We have presented the case of a woman with unilateral occlusion of a tube ovulated permanently on the same side. The other ovary and tube were intact. To overcome this problem, we gave full menotropic treatment to induce super-ovulation, and the patient became pregnant in the second treatment cycle. We think medical treatment should be attempted before paradoxical oophorectomy is contemplated in women with unilateral occlusion who cannot become pregnant.

Adult↗
PubMed1986

Face presentation.

The diagnosis, aetiology, management and outcome of face presentation were analyzed in 51 cases. Primigravidas accounted for 17.6%, multiparas for 54.9% and grand multiparas (5 deliveries or more) for 27.5%. Prematurity did not appear to be an important aetiologic factor. The position was mentum anterior in 26 patients (51%), all but one of whom were delivered vaginally. Of 12 fetuses in the mentum transverse position, 11 were delivered vaginally after spontaneous rotation to mentum anterior. Ten patients presented with mentum posterior; only 2 were delivered vaginally after spontaneous rotation. Three fetuses were diagnosed as face presentation during Caesarean section. The mean birth-weight of the infants who rotated from mentum posterior to mentum anterior was 3,425 +/- 35g, while that of those with persistent mentum posterior was 3,792 +/- 347 (p less than 0.01). Records of monitored fetal heart rate were available in 21 cases. Late decelerations and variable decelerations were recorded in 6 (28.5%). The incidence of Caesarean section was 25.5% compared to an overall incidence of 4.4% during the period of the study. Oxytocin was administered to 10 patients, and 7 of them were delivered vaginally. Early diagnosis of presentation and position, with close fetal surveillance may improve fetal outcome. In case of mento-posterior position, primary Caesarean section at term should be considered.

Adult↗
PubMed1986

Urinary retention caused by impaction of leiomyoma in pregnancy.

Complete urinary retention caused by incarceration of a retroverted gravid uterus or large fibroid uterus is a rare condition. The following case report illustrates the acute onset of urinary retention caused by the combination of a large leiomyoma and pregnancy. Total hysterectomy was performed. To the best of our knowledge, such a combination has not been reported previously.

Adult↗