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Biomedical subjects

M Ginzburg

Publications and source records attributed to M Ginzburg.

At least 19 recordsLinked to original sources
PubMed2000

Shaped ceramics with tunable magnetic properties from metal-containing polymers

A shaped, magnetic ceramic was obtained from a metal-containing polymer network, which was synthesized by thermal polymerization of a metal-containing organosilicon monomer. Pyrolysis of a cylinder, shape, or film of the metal-containing polymer precursor produced a low-density magnetic ceramic replica in high yield. The magnetic properties of the shaped ceramic could be tuned between a superparamagnetic and ferromagnetic state by controlling the pyrolysis conditions, with the particular state dependent on the size of iron nanoclusters homogeneously dispersed throughout the carbosilane-graphitic-silicon nitride matrix. These results indicate that cross-linked metal-containing polymers may be useful precursors to ceramic monoliths with tailorable magnetic properties.

Journal Article↗
PubMed1999

GABAergic activation inhibits the hypothalamic-pituitary-ovaric axis and sexual development in the immature female rat. Associated changes in hypothalamic glutamatergic and taurinergic systems.

The aim of the present studies was to assess, in immature female rats, the effect of the GABAergic system on the reproductive axis and on pubertal development. With this purpose we initially evaluated, in 30-day-old female rats, the effect of persistently enhanced GABAergic activity (aminooxyacetic acid (AOAA) 10 mg/kg per day i.p., during postnatal days 23-29) on hypothalamic gonadotropin-releasing hormone (GnRH) and amino acid neurotransmitter (AANT; glutamate or GLU, and taurine or TAU) concentrations, on circulating luteinizing hormone (LH) and estradiol levels, and on ovaric weight. In a second group of similarly treated rats, the date of vaginal opening (VO) was recorded. Complementary in vitro experiments (superfusion of anterior/mediobasal hypothalamic fragments obtained from rats aged 30 days) were performed to evaluate the effect of the short-term activation of the GABAergic system (by means of AOAA, muscimol or baclofen) on hypothalamic GnRH and AANT release. Prolonged treatment with AOAA led to a marked increase in hypothalamic gamma-aminobutyric-acid (GABA) concentrations (p<0.002), and to a significant decrease in hypothalamic GnRH and GLU content (p<0.05 and <0.02, respectively). Furthermore, treated animals showed diminished serum LH (p<0.05) and estradiol (p<0.005) levels, and a clear reduction in ovaric weight (p<0.002). Mean age at VO was 30. 8+/-0.6 days in control animals (range: 29-34 days), and 36.7+/-0.98 days in AOAA-treated rats (range: 33-40 days; p<0.0001). Acute treatment with AOAA resulted in a decreased GnRH and GLU output, and in an increased TAU release from superfused hypothalamic fragments. This effect was mimicked by the GABA-A and GABA-B agonists. Our results show that the activation of the GABAergic system during postnatal days 23-29 significantly restrains the hypothalamic-pituitary-ovaric axis, resulting in a clear-cut delay in sexual development. This can be attributed to the inhibitory effect exerted by GABA (acting on both GABA-A and GABA-B receptor subtypes) on GnRH release. Furthermore, the pharmacologic manipulation of the GABAergic system induces significant changes in the release of GLU and TAU, giving biochemical support to the existence of a physiological cross-talk between the excitatory and inhibitory AANT regulating GnRH release during the onset of puberty.

Aminooxyacetic Acid↗
PubMed1998

Changes in mediobasal hypothalamic dopamine and GABA release: a possible mechanism underlying taurine-induced prolactin secretion.

Taurine (Tau), a putative inhibitory amino acid neurotransmitter, has been shown to stimulate prolactin (PRL) release. Using ovariectomized, estrogen-replaced adult rats we investigated initially the effect of this amino acid, injected by different routes, on PRL secretion in vivo. Tau (100-500 mg/kg) had no effect on PRL release when given i.p.; 15 min after i.c.v. injection of Tau (3 mumoles), a significant increase in serum PRL levels was observed (78 +/- 9 ng/ml over basal levels, p < 0.01 vs. controls). In vitro (cultured anterior pituitary cells) PRL release was not affected by a 5 h incubation with Tau (10(-3)-10(-8) M). Basal dopamine (DA) or gamma-aminobutyric acid (GABA) output from superfused mediobasal hypothalamic fragments (MBH) was not affected by Tau (10(-3) M or 10(-5) M). However, during stimulation with KCl (50 mM), Tau (10(-3) M) significantly lowered DA release, and increased GABA output. It is concluded that Tau acts at a central level to increase PRL secretion, most probably by modulating the hypothalamic release of neurotransmitters controlling lactotroph function.

Animals↗
PubMed1995

Repeated intracerebroventricular administration of taurine lowers LH levels and postpones vaginal opening in peripubertal female rats.

UNLABELLED: We investigated the effect of repeated intracerebroventricular injections of taurine (Tau, 0.15 mumol/3 microliters distilled water), administered during postnatal days 23-29, on serum LH levels, and on the hypothalamic content of LHRH and amino acid neurotransmitters (measured by HPLC and electrochemical detection) in 30-day-old female rats (n = 18). Treatment with Tau lowered serum LH (Tau: 0.20 +/- 0.04; CONTROLS: 1.04 +/- 0.21 ng/ml RP3; mean +/- S.E.M.; P < 0.05) as well as hypothalamic LHRH levels (Tau: 82.6 +/- 9.5; controls: 128.7 +/- 14.1 pg/mg wet tissue, P < 0.05). Tau treatment doubled hypothalamic GABA levels (Tau: 31.3 +/- 2.9; CONTROLS: 15.6 +/- 1.2 nmoles/mg wet tissue, P < 0.001). In a second group of animals (n = 13), Tau treatment delayed vaginal opening by more than 2 days (P < 0.05 vs. controls). It is concluded that supplementation with Tau during the fourth postnatal week reduces LHRH/LH secretion and postpones sexual development, perhaps by increasing the activity of the hypothalamic GABAergic system.

Amino Acids↗
PubMed1993

The reliability of midstream urine culture from circumcised male infants.

The reliability of midstream urine culture from circumcised male infants was studied in 60 infants aged 1 to 21 weeks. A midstream urine specimen was collected after cleansing the penis. When the bladder was full again, a suprapubic bladder aspiration (SPA) was also performed. The results of the urine cultures were almost identical in specimens obtained midstream and by SPA. In 37 infants the cultures were sterile and in 13 positive, with the same microorganism being cultured in both instances. In one case, few colonies of Staphylococcus epidermidis grew only from the midstream culture. In nine infants, only midstream specimens were obtained because three attempts at SPA were unsuccessful. These results suggest that in circumcised male infants, the midstream method of obtaining urine for a culture is as reliable as SPA.

Circumcision, Male↗
PubMed1992

Serum soluble interleukin-2 receptor levels are associated with clinical disease status and histopathological grade in non-Hodgkin's lymphoma and chronic lymphocytic leukemia.

Serum soluble Interleukin-2 receptor levels (sIL-2R) were measured in 121 patients (pts) with non-Hodgkin's lymphoma (NHL) and in 30 patients with Chronic lymphocytic leukemia (CLL). Sera collected from 32 normal volunteers and 18 patients with infection or a variety of non malignant hematological disorders served as controls. A small number of patients with Hairy cell leukemia (HCL) and Hodgkin's disease (HD) were also studied. NHL patients were classified according to their clinical status as "active" (82 pts) or "non-active" (39 pts) and CLL according to the stage of their disease. NHL patients were also further classified as low (55 pts), intermediate (38 pts) and high grade malignancy (28 pts), according to the Working formulation scheme. A significant difference was found between the high levels of sIL-2R in patients with "active" disease and the lower levels in patients with quiescent or responsive disease. Significantly different high levels were found in patients with aggressive (intermediate and high grade) lymphoma as opposed to low grade lymphoma and CLL. In CLL itself higher levels of sIL-2R were seen in more advanced disease than in early disease. Thirteen patients with active Hodgkin's disease (HD) had moderately elevated sIL-2R levels, similar to those recorded for patients with infections and some non-malignant hematological disorders while another 13 HD patients in remission, had normal levels comparable to those recorded in normal controls. Extremely high levels of sIL-2R were seen in 2 patients with HD with severe viral infections and levels approaching those seen in HCL, were noted (20-30,000 u/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1990

Haloarcula marismortui (Volcani) sp. nov., nom. rev., an extremely halophilic bacterium from the Dead Sea.

An extremely halophilic red archaebacterium isolated from the Dead Sea (Ginzburg et al., J. Gen. Physiol. 55: 187-207, 1970) belongs to the genus Haloarcula and differs sufficiently from the previously described species of the genus to be designated a new species; we propose the name Haloarcula marismortui (Volcani) sp. nov., nom. rev. because of the close resemblance of this organism to "Halobacterium marismortui," which was first described by Volcani in 1940. The type strain is strain ATCC 43049.

Archaea↗
PubMed1986

The primary role of the Erb's point--axilla segment in median and ulnar motor nerve conduction determinations in alcoholic neuropathy.

Motor nerve conduction velocity (MNCV) was explored in the Erb's point-axilla (N-A) nerve segment of median and ulnar nerves, bilaterally, in 10 patients with a history of prolonged heavy drinking but in whom no other predisposing factors to peripheral neuropathy were found. For comparison, MNCV was determined also in the axilla-elbow (A-E), elbow-wrist (E-W) nerve segments, as well as the motor terminal latency (MTL) of the same nerves. A total of 140 nerve segments were tested tested but only 133 results were obtained. Abnormal MNCV or MTL was found in 36 or 27% of all tested nerve segments. From the latter, 38.9% were in the N-A nerve segments. Of N-A nerve segments tested, reduction in MNCV was found in 46.7%. Our results are statistically significant.

Adult↗
PubMed1979

Distribution of non-electrolytes in Halobacterium cells. I. Halobacterium marismortui.

Halobacterium marismortui is an obligatorily halophilic species isolated from the Dead Sea. When inulin, fructose or glycerol are added to suspensions of bacteria, the amounts of these substances recovered from centrifuges pellets are more than could have been present in the extracellular space. Thus a certain amount becomes associated with the bacteria, though not enough to equilibrate with all the cell water. The inulin or fructose concentration found after uptake of these substances was correlated with the cell sodium concentration. It is argued that inulin, fructose or glycerol is unlikely to be adsorbed on the outside of the bacteria and more probably crosses the plasma membrane. A possible scheme for explaining the data is presented.

Cell Membrane Permeability↗
PubMed1978

Passive electrical properties of Halobacterium species. I. Low-frequency range.

The electrical conductivity of suspensions of two species of Halobacterium was measured at low A. C. frequency. The results obtained from Halobacterium halobium suspensions show that the bacteria act as non-conducting particles. In contrast, the cells of a Halobacterium obtained from the Dead Sea (Halobacterium marismortui) had an apparently high conductivity which can be explained partly in terms of the cell-membrane being pierced by pores through which ions can move freely and partly in terms of highly concentrated cell ions, all of which are mobile.

Cell Count↗
PubMed1978

Median and ulnar nerve conduction determinations in the Erb's point--axilla segment in normal subjects.

Twenty-one median and 22 ulnar nerves were tested in 12 patients for motor nerve conduction velocity (MNCV) and motor nerve conduction time (MNCT) in the segments from Erb's point (N) to axilla (A) bilaterally. It was found that on this segment for both nerves, MNCV values equal to or smaller than 51 m/s or conduction times equal to or longer than 4 ms are to be considered abnormal. For comparative studies and for checking the normality of the tested nerves in their entire length, the more distally located segments in the same nerve were also tested. For diagnostic purposes, the differences between right and left MNCV or MNCT values determined in the same person on N-A segments of homologous nerves were analysed. Motor nerve conduction velocity or MNCT determinations on the N-A nerve segment are expected to replace MNCV determinations on the longer N-AE (AE=100 mm above elbow) nerve segment, which is now in use, for diagnosis of the thoracic outlet syndrome.

Adult↗
PubMed1976

Regulation of cell volume and ion concentrations in a Halobacterium.

Changes in cell volume and ion content of a Halobacterium species are described in terms of the NaCl concentration (0.5--3.5M) and pH(4-8) of the suspending medium. Cell volume, per unit content of protein of bacteria in stationary phase cultures, rose as the [NaCl] of the growth medium was increased. Logarithmic-phase bacteria shrank as the pH fell from 7 to 5.5. These changes are characteristic of bacteria with a moderate or rapid rate of O2 consumption. Starving (i.e. nonmetabolizing) bacteria, on the other hand, did not change in size within the above ranges of [NaCl] and pH. At lower values, however, such bacteria swelled and eventually lysed. Effects of low pH on cell ions are compared in metabolizing and starving bacteria, and it is shown that changes in the state of the cell K are correlated with movements of cell Na. It appears that the cell K is used to maintain cell [Na] below the NaCl concentration of the medium. The results are explained in terms of a model involving interactions between polyelectrolytes, salts and water in the concentrated cytoplasm of these halophilic organisms.

Bacterial Proteins↗