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Biomedical subjects

A Bak

Publications and source records attributed to A Bak.

35 records · Page 2Linked to original sources
PubMed1998

[A case of congenital uveal ectropion with glaucoma].

A case of 21-year-old man with a rare congenital syndrome of uveal ectropion with glaucoma is described. The visual acuity was 1.0 with correction cyl. -1.0 axis 100 degrees. The highest intraocular pressure was 55 mm Hg. The optic nerve was damaged with glaucomatous cupping (cup/disc ratio 0.8). The visual field presented adequate few insular scotomas. The glaucoma filtering surgery was performed: goniotrepanatio by Fronimopoulos. After the surgery in one year observation intraocular pressure was about 15 mm Hg. The perimetry showed no increase in optic disc damage. We wanted to present this case because of its rare occurrence and good results of the surgery.

Adult↗
PubMed1997

Review article: treatment of Clostridium difficile infection.

AIM: A systematic review of controlled trials of therapy of Clostridium difficile intestinal infection using methodology described by the Cochrane Collaboration. METHODS: Trials were identified by searching computer databases over the years 1978-1996. Trials were included if they were (a) prospective randomized, controlled trials and (b) included patients with symptomatic disease. The primary end-point was clinical resolution of diarrhoea. Secondary end-points were clinical relapse and stool clearance of C. difficile and C. difficile toxin. RESULTS: Nine trials (469 patients) satisfying the inclusion criteria were identified. Two trials were placebo controlled. Six trials compared vancomycin to other antibiotics (fusidic acid, bacitracin, teicoplanin and metronidazole). For clinical resolution response rates ranged from 21 (placebo) to 100% (vancomycin). On pooling the trials, no antibiotic showed clear therapeutic superiority. Rates of clinical relapse ranged from 5 to 42%. Only one trial showed significant advantage of one antibiotic over another for prevention of relapse (teicoplanin vs. fusidic acid). CONCLUSION: The published data are limited, and further studies are required.

Anti-Bacterial Agents↗
PubMed1997

[A case of Cogan-Reese syndrome (iris nevus syndrome)].

A case of 37 years old woman with a classic form of Cogan-Reese iris naevus syndrome is presented. Closure angle glaucoma, being a part of syndrome, with glaucomatous disc damage was initially treated with drugs (betaxolol, trusopt) without effective IOP decrease. A surgery was performed (goniotrepanatio by Fronimopoulos modified by Palmberg, but without iridectomy), 5 fluorouracil subconjunctival injections were given to the patient postoperatively for 5 days. We received a good IOP control on the level of 12 mm Hg. The visual acuity was 1.0 after surgical procedure. We wanted to present this case because of its rarity and a typical surgical procedure (without applying iridectomy).

Adult↗
PubMed1995

Factors affecting the developmental stage of embryos recovered on day 7 from superovulated dairy cattle.

The objective of this retrospective study was to evaluate the factors influencing developmental stage of bovine embryos recovered from superovulated dairy cattle 7 d after estrus. From 217 superovulated dairy cows and heifers, 2,211 eggs were recovered, of which 1,495 were classified as transferable embryos based on morphological evaluation of developmental stage and quality. From the evaluated embryos, 1,429 were non-surgically transferred to recipients to produce 623 calves. The transferable embryos were classified into five developmental stages and four quality grades. The least-developed transferable embryos tended to be classified into poorer quality grades. A multifactorial statistical model was used to analyze whether the following factors were associated with the developmental stage and quality grade of the embryos: donor breed, parity, gonadotropin preparation, embryo sex, insemination bull, embryologist (the person evaluating the embryo), year, and season of recovery. Among these factors, only the embryologist and the donor animal accounted for significant variation in embryo development. It was concluded that the developmental stage of embryos recovered at d 7 from superovulated cattle, when evaluated by simple morphological criteria, was correlated with the embryo's quality and was affected by the donor animal but in this study not by the embryo sex, donor breed and parity, gonadotropin preparation, and insemination bull used. The embryo's quality grading was influenced by the embryologist. Consequently, sexing of an embryo recovered from superovulated cattle is not possible by simple morphological evaluation of the embryo's developmental stage.

Animals↗
PubMed1995

An automated hematology laboratory with computer-controlled robotics.

A highly automated hematology laboratory environment is described that has conveyance systems to move bar-coded specimens from one station ("workcell") to another, robotic handling devices to load and unload hematology analyzers, and a hematology workstation. Computer systems monitor the process and equipment, track the specimen, manage inventory, and interpret patient results. When a specimen arrives at the laboratory, the bar-code determines which workcell the specimen should go to for testing. Each specimen is handled individually and in real-time. Hematology specimens are routed to a workcell of Coulter STKS analyzers where complete blood counts with five-part leukocyte differentials are performed under full robotic control. The entire process is managed by a real-time Windows-based process control system that interacts with a networked laboratory information system. The hematology workstation is being evaluated for interpretive results reporting and to determine follow-up testing.

Clinical Laboratory Information Systems↗
PubMed1992

Tunicamycin reduces Na(+)-K(+)-pump expression in cultured skeletal muscle.

The purpose of this study was to examine effects of tunicamycin (TM), which inhibits core glycosylation of the beta-subunit, on functional expression of the Na(+)-K+ pump in primary cultures of embryonic chick skeletal muscle. Measurements were made of specific-[3H]-ouabain binding, ouabain-sensitive 86Rb uptake, resting membrane potential (Em), and electrogenic pump contribution to Em (Ep) of single myotubes with intracellular microelectrodes. Growth of 4-6-day-old skeletal myotubes in the presence of TM (1 microgram/ml) for 21-24 hr reduced the number of Na(+)-K+ pumps to 60-90% of control. Na(+)-K+ pump activity, the level of resting Em and Ep were also reduced significantly by TM. In addition, TM completely blocked the hyperpolarization of Em induced in single myotubes by cooling to 10 degrees C and then re-warming to 37 degrees C. Effects of tunicamycin were compared with those of tetrodotoxin (TTX; 2 x 10(-7) M for 24 hr), which blocks voltage-dependent Na+ channels. TM produced significantly greater decreases in ouabain-binding and Em than did TTX, findings that indicate that reduced Na(+)-K+ pump expression was not exclusively secondary to decreased intracellular Na+, the primary regulator of pump synthesis in cultured muscle. Similarly, effects of TM were significantly greater than those of cycloheximide, which inhibits protein synthesis by 95%. These findings demonstrate that effects were not due to inhibition of protein synthesis. We conclude that glycosylation of the Na(+)-K+ pump beta-subunit is required for full physiological expression of pump activity in skeletal muscle.

Animals↗
PubMed1992

Use of PMSG antiserum in superovulated cattle?

Two Pregnant Mare Serum Gonadotrophin (PMSG) antisera were tested in 174 dairy cows that were superovulated with PMSG and were then given prostaglandin at 60 hours after PMSG. At 48 hours after injection of prostaglandin, the cows were given either PMSG antiserum (monoclonal (n=56) or polyclonal (n=57)), or saline as control (n=61). Ova (n=1,206) were recovered either nonsurgically or after slaughter. Of these, 757 were evaluated morphologically to be transferable embryos. A proportion of these embryos (n=295 from 52 flushed donors) were transferred to synchronized recipients and the pregnancy results were recorded. The reproductive function of 37 flushed donors was followed for 6 months after superovulation. No significant effect of the PMSG antisera could be demonstrated in any of the parameters studied (i.e., ovulation rate, number of follicles at collection, total yield of ova, fertilization rate, number of transferable embryos, pregnancy results after transfer of embryos, or period required by the donor cows for restitution of reproductive function after superovulation and recovery). It is concluded that use of PMSG antiserum did not improve the embryo yield in terms of the number and quality of transferable embryos or enhance normalization of reproductive function of the donor in the 6-month period after superovulation. Therefore, in an embryo transfer operation, the routine use of PMSG antiserum in a PMSG superovulation regimen in cattle is not recommended.

Journal Article↗
PubMed1991

Bisection of bovine morulae and blastocysts from superovulated Danish dairy cows.

Sixtyfour compacted morulae and blastocysts were bisected with a microscalpel. The majority of the demi-embryos (n = 122) were reinserted into separate zona pellucidae (ZP) before non-surgical transfer to 113 synchronized recipients, as singles (n = 98) (DE-S) or in pairs (n = 30) (DE-P). Thirty non-manipulated embryos (E) were transferred during the same period and served as controls. Pregnancies were diagnosed by rectal palpation 4-7 weeks after transfer. The pregnancy rates for DE-S, DE-P and E were 32%, 53% and 40%, respectively (P greater than 0.05). A substantial number of abortions were recorded between 50 and 250 days of pregnancy among the recipients with DE-S. The fetal survival rate for DE-S was reduced to 21% and significantly lower (p less than 0.05) than the survival rates of DE-P (43%) and E (40%). The quality of DE and the presence of ZP did not significantly influence the results. No conclusive reasons for the fetal loss could be found but different possibilities are discussed.

Animals↗
PubMed1990

Preovulatory plasma estradiol-17beta concentrations and ovulation rates in PMSG/anti-PMSG treated heifers.

Possibilities for early characterization of the superovulatory response were studied in 41 PMSG/PG-treated dairy heifers, of which 21 received an additional treatment of PMSG-antiserum. Plasma was obtained at 33, 36, 41, 47 and 51 h after PG for hormone analyses. After slaughter at 6 or 7 d after insemination, the number of follicles and corpora lutea (CL) were recorded, and ova were recovered for morphological evaluation. Significant correlations were demonstrated between plasma concentrations of estradiol-17beta (E2) at 33, 36 and 41 h after PG and the ovulation rate (number of CL). Each of these correlations was equal to the one found by using the peak concentration of E2 achieved during the preovulatory E2 surge. In heifers with preovulatory E2 surges, as determined with the blood sampling scheme used, both the ovarian response (number of CL and follicles) and the quality of ova recovered (number of transferable embryos) was clearly better compared to heifers without this surge. None of the parameters studied was affected significantly by treatment with PMSG-antiserum. It is concluded that plasma E2 determinations at fixed times in relation to prostaglandin treatment can be used to characterize the superovulatory response in donor cattle in terms of the ovulation rate and the quality of ova recovered. No evidence was found in favor of using PMSG-antiserum for improving either the superovulatory response or such characterization.

Journal Article↗
PubMed1989

Differential cleavage rates and sex determination in bovine embryos.

The purpose of this study was to determine whether a correlation between embryonic cleavage rates and sex ratios in dairy cattle could be substantiated. Embryos were collected at Day 7 after estrus following superovulation and artificial insemination. Embryos from flushings where at least two different developmental stages within the same flushing could be identified were examined. A total of 476 such embryos was transferred to recipients and 110 calves were born. The sex effect was only demonstrable in flushings yielding embryos of at least three different developmental stages. The sex ratios from this group were 32%, 58% and 62% in the slow, intermediate and fast developing groups of embryos, respectively. The deviations were not significant (P = 0.084). Only 23% of the flushings provided embryos that fell into this cathegory, which limits the use of differential cleavage rates as a sexing method, unless additional embryo culture is introduced to the technique.

Journal Article↗
PubMed1987

Role of Na-K ATPase in regulation of resting membrane potential of cultured rat skeletal myotubes.

The role of Na-K ATPase in the determination of resting membrane potential (Em) as a function of extracellular K ion concentration was investigated in cultured rat myotubes. The Em of control myotubes at 37 degrees C varied as a function of (K+)0 with a slope of about 58-60 mV per ten-fold change in (K+)0. Inhibition of the Na-K pump with ouabain or by reduced temperature revealed that this relation consists of two components. One, between (K+)0 of 10 and 100 mM, remains unchanged by alterations in enzyme activity; The second, between (K+)0 of 1 and 10 mM, is related to the amount of Na-K pump activity, the slope decreasing as pump activity decreases. Indeed, with complete inhibition of the Na-K pump, Em does not change over the range of (K+)0 1 to 10 mM. Measurements of 86Rb efflux and input resistance of individual myotubes showed that membrane permeability does not change as (K+)0 increases from 1 to 10 mM but increases as (K+)0 increases further. Monensin, which increases Na ion permeability, increases Em at values of external K+ below 10 mM, and is without effect at higher values of K+ concentration. The effect of monensin is blocked by ouabain. Tetrodotoxin, which blocks voltage-dependent Na+ channels, decreases Em at low (2-10 mM) K+. We conclude that changes in Em as a function of extracellular K+ concentration in the physiological range are not adequately explained by the diffusion potential hypothesis of Em, and that other theories (electrogenic pump, surface-absorption) must be considered.

Animals↗
PubMed1986

Some electrophysiological properties of cultured rat cerebral cortical neurons dissociated from fetuses at various gestational ages.

Neurons from dissociated cerebral cortex of fetal rat of different gestational ages were grown in culture for up to 4 weeks. Studies of membrane and action potentials, input resistance, neuron size and neurite outgrowth showed that neurons from 7-day fetuses develop rapidly both electrophysiologically and morphologically, but are maintained for only about 2 weeks. In contrast, neurons from 14 to 17 day fetuses mature slowly, but can be maintained for at least 4 weeks. Neurons from both young and old fetuses show an increase in resting Em with age, the maximum value of -60 to -65 mV being attained by about 2 weeks. While neurons can be maintained in serum-free medium, their membrane electrical properties deteriorate with time. Thus, appropriate development of neurons in culture depends upon both the age of the starting tissue, and the presence of adequate, but still undefined factors found in animal serum for at least the first several days in culture.

Action Potentials↗
PubMed1985

Dependence of Na+,K+-ATPase and electrogenic component of Em in cultured myotubes on cell fusion.

This study was undertaken in order to determine the relation among cell fusion, [3H]ouabain binding and the membrane potential (Em) of cultured rat skeletal muscle. The amount of ouabain bound and the Em both increased with age, the increases being most dramatic following fusion. Inhibition of fusion prevented the developmental increases in both properties of cultured muscle. After fusion, the size of the electrogenic component of Em, determined by the decrease in Em produced by ouabain within 5-10 min, increased independent of the age at which fusion occurred. It is concluded that the increase in Em with age depends on postfusion appearance and activity of Na,K-ATPase.

Animals↗
PubMed1973

Hair cell generator potentials.

A technique is introduced using a piezoelectric device to stimulate hair cells of a molluscan statocyst while recording their responses intracellularly. Statocyst displacements produced with the technique are calibrated with stroboscopic photography. Properties of the hair cells' response to currents and mechanical stimulation are studied. The hair cell generator potential arises from a conductance increase and, for a certain range, is a logarithmic function of the amplitude of the displacement stimulus.

Animals↗