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Biomedical subjects

M Tucker

Publications and source records attributed to M Tucker.

At least 19 recordsLinked to original sources
PubMed1992

Validity and reliability of the Neurobehavioral Assessment Scale.

The Neurobehavioral Assessment Scale (NAS) was developed to measure the full range of behavioral functioning from fully alert to deep coma. This investigator-rated scale was evaluated in 60 patients undergoing conscious sedation for maxillofacial procedures. The results obtained on the NAS were reliable, as evidenced by high correlations between the rating of the two raters. The scale is also valid as determined by high correlations between the NAS and a standard scale, the Glasgow Coma Scale (criterion validity) and between the NAS and the Digit Symbol Substitution Test (behavioral validity). The NAS clearly distinguished between two levels of sedation (heavy and light). Furthermore, the NAS appears to be better able to discriminate among the different degrees of sedation in lightly sedated patients than the Glasgow Coma Scale.

Adolescent↗
PubMed1992

Selective assisted hatching of human embryos.

Overall results of assisted hatching by zona drilling using acidic Tyrode's solution performed during three randomised trials in 330 in vitro fertilisation (IVF) patients are presented. It was demonstrated retrospectively and prospectively that assisted hatching by zona drilling was effective in embryos with thick zonae (> 15 microns). This procedure is called selective assisted hatching. In order to investigate whether the success rate of embryos with thin zonae (< 13 microns) can be improved further, a fourth trial was executed in 40 consenting patients. Embryos with thin zonae were left intact in one group (control), while the outside of zonae of similar embryos were thinned with acidic Tyrode's solution. Results thus far indicate that embryos with thin zonae do not benefit from this technique. Embryonic implantation (fetal heartbeat per embryo) was high (26%-27%) in both arms of the trial, probably as a result of selective zona drilling of low prognosis embryos with thick zonae. A method is presented for quantifying zona hardening in human embryos. The exposure to acidic Tyrode's solution of each embryo was expressed as a function of the duration to pierce the zona and the diameter of the needle. Preliminary findings suggested that embryonic viability is correlated with zona hardening. In order to test the hypothesis that extracellular fragments may affect embryonic viability, small amounts of fragments were removed from embryos during assisted hatching. The pregnancy rate in 36 patients with extracted fragments was relatively high (41%) considering the poor morphology of the embryos involved.

Adult↗
PubMed1991

Poor implantation of cryopreserved reinsemination-fertilized human embryos.

OBJECTIVE: To investigate whether a poor rate of implantation after in vitro fertilization (IVF) was due to poor embryonic/endometrial synchrony during the original IVF cycle, we have cryopreserved reinseminated-fertilized embryos for later more synchronous replacement after thawing. The chance of implantation of fresh reinseminated fertilized human oocytes is approximately one tenth that of timely fertilized embryos. STUDY DESIGN AND DATA: Retrospective study of 35 original oocyte collections in which initial normal fertilization was 47.3% (129/273 oocytes), with 49.6% fertilization (67/135) upon reinsemination. Of these, 70 initially fertilized and 67 reinsemination-fertilized embryos were cryopreserved, and 50 initially fertilized and all 67 reinsemination-fertilized embryos were subsequently thawed with 72% and 63% cryosurvival, respectively, (not significant). SETTING: Private infertility clinic. RESULTS: In 11 cycles, 23 thawed initially fertilized embryos (group A) were replaced with a 21.7% implantation rate per embryo; in 10 cycles, 13 initially fertilized and 12 reinsemination-fertilized embryos (group B) were replaced together with an 8% implantation rate; finally, in 16 cycles, 30 reinsemination-fertilized embryos (group C) were replaced with a 3.3% implantation rate (group A versus group C: P = 0.076). Comparison of clinical pregnancies between these groups was significantly different (6/11 versus 1/16; P = 0.0427). CONCLUSION: Reinsemination-fertilized embryos survive freezing as well as initially fertilized embryos, but better embryonic/endometrial synchrony does not improve chances of their implantation.

Adult↗
PubMed1990

Behavior of acyl carrier proteins on western blots.

Acyl carrier proteins (ACPs) from Escherichia coli and Euglena were analyzed on Western blots using rabbit antibodies raised against E. coli ACP. Euglena ACP, unlike that from E. coli, behaves upon electrophoresis under denaturing conditions as its size would predict. Oligomeric forms of both ACPs were evident on Western blots, but the bacterial ACP had more tendency to aggregate. That the oligomeric forms were not due to impurities was shown by their regeneration from low-Mr protein, reaction with antibodies isolated from low-Mr protein, and by molecular weight determination of the ACP by low-angle laser light scattering.

Acyl Carrier Protein↗
PubMed1990

Ethanol inhibits zymosan-stimulated and enhances nonstimulated platelet-activating factor production in a clonal macrophage cell line.

Ethanol was examined for its effects on zymosan phagocytosis and synthesis of platelet-activating factor (PAF) using a clonal macrophage cell line. PAF, identified as 1-O-alkyl-2-acetyl-sn-glycerol-3-phosphocholine, is a biologically active ether phospholipid produced by various cells types. PAF also activates a variety of inflammatory cells including the cells which produce PAF. Ethanol at 20 to 100 mM inhibited phagocytosis of unopsonized zymosan and concomitantly decreased PAF concentration in the stimulated macrophages. In contrast, in cells not stimulated with zymosan, ethanol increased the recoverable PAF. Ethanol, at 100 mM, inhibited the uptake of exogenous PAF but did not alter the distribution of PAF metabolites in the clonal macrophage cell line. The effect ethanol has on PAF synthesis appears dependent on the activation state of the cell. Two situations were identified in this study: 1) one linked to phagocytosis or cell stimulation which is inhibited by ethanol, and 2) PAF synthesis which is not dependent on overt cell activation that is enhanced by ethanol.

Animals↗
PubMed1989

One hundred pregnancies after treatment with pulsatile luteinising hormone releasing hormone to induce ovulation.

OBJECTIVE: To review treatment with pulsatile luteinising hormone releasing hormone in infertile women who do not ovulate and are resistant to clomiphene after 100 pregnancies achieved with this treatment. DESIGN: Retrospective analysis of 146 courses of treatment over 434 cycles. SETTING: Infertility clinic. PATIENTS: 118 Women whose failure to ovulate was due to idiopathic hypogonadotrophic hypogonadism (n = 39), amenorrhoea related to low weight (n = 17), organic pituitary disease (n = 15), or polycystic ovaries (n = 47). INTERVENTIONS: Dose of 15 micrograms luteinising hormone releasing hormone/pulse subcutaneously every 90 minutes given with a miniaturised pump throughout cycle monitored by ultrasound. Women with hypogonadotrophic hypogonadism had 48 courses, women with amenorrhoea related to low weight 23, women with organic pituitary disease 18, and women with polycystic ovaries 57. END POINT: Follow up of 100 pregnancies achieved in 77 women during six years after introducing treatment. MEASUREMENTS and main results--One hundred pregnancies (seven multiple, 28 miscarriages). Cumulative rates of pregnancy were 93-100% at six months in women with idiopathic hypogonadotrophic hypogonadism, amenorrhoea related to low weight, and organic pituitary disease. In women with polycystic ovaries (cumulative rate of pregnancy 74%) adverse prognostic factors were obesity, hyperandrogenism, and high luteinising hormone concentrations, which were also associated with a high rate of early pregnancy loss. CONCLUSIONS: Treatment with pulsatile luteinising hormone releasing hormone is safe, simple, and effective, and the preferred method of inducing ovulation in appropriately selected patients. Compared with exogenous gonadotrophin treatment there is little need for monitoring, no danger of hyperstimulation, and a low rate of multiple pregnancies.

Abortion, Spontaneous↗
PubMed1988

Synergism of pulsatile LHRH therapy with oral clomiphene treatment.

Eighteen anovulatory patients who were resistant to induction of ovulation with clomiphene and with subcutaneous pulsatile LHRH were treated with these two agents given simultaneously. Twelve of the 14 patients with polycystic ovary syndrome, 1 patient with weight-related amenorrhea and 1 of 3 patients with intrinsic pituitary disease responded to the combined treatment. Serial determinations of serum gonadotropin concentrations showed that these remained unchanged by clomiphene treatment, suggesting a direct action on the ovary. For induction of ovulation for in vivo fertilization, the combination of oral clomiphene with subcutaneous pulsatile LHRH is worth trying before proceeding to intravenous LHRH or hMG therapy.

Administration, Oral↗
PubMed1986

Different calcium dependence of the capping and cutting activities of villin.

The concentration of ionized calcium required for the capping of barbed filament ends by villin is about 4 orders of magnitude lower than that required for the cutting activity of villin. Capping was 50% complete at about 10-30 nM Ca2+, a level expected in resting cells, whereas the cutting rate was half-maximal at about 200 microM, making it possible to completely separate filament capping from filament cutting. Analysis of capping in terms of coupled equilibria between calcium binding to villin and calcium-villin binding to the barbed ends of actin filaments gives a value of 10(16)-10(17) M-2 for the product of the two binding constants. By comparison the binding constant reported for the rapidly exchanging calcium sites on villin is 2 X 10(5) M-1 and that for binding of calcium-saturated villin to barbed ends has a minimum value of 10(11) M-1 giving a product of 2 X 10(16) M-1. The close similarity of the two sets of values suggests that capping is regulated by the rapidly exchanging calcium sites on villin. In terms of coupled equilibria the calcium requirement for filament capping decreases with increasing concentrations of free villin. The scant information on the mechanism of cutting allows only an estimate of the maximal value for the calcium-binding constant of the site regulating cutting which is about 2-5 X 10(3) M-1. Cutting is followed by rapid capping of the newly released barbed ends.

Actins↗
PubMed1985

Successful pregnancies from the transfer of pronucleate embryos in an outpatient in vitro fertilization program.

Twenty-nine infertile women were given clomiphene citrate (100 mg/day, days 3 to 7), human menopausal gonadotropin (150 IU/day, days 7 to 12 or 13), and human chorionic gonadotropin (2000 IU) for the induction of ovulation. Eggs were collected by laparoscopy and preincubated for 6 hours before being cultured with spermatozoa for fertilization. Approximately 16 to 18 hours after insemination, the eggs that showed two pronuclei were transferred to the patient's uterus. As confirmed by the ultrasonic appearance of a gestational sac, six women who received pronucleate embryos became pregnant, and three pregnancies resulted in normal full-term deliveries. These results confirm that, unlike requirements for most laboratory and farm animals, the requirements of synchrony between the preimplantation human uterus and developing embryos are not very stringent. In vitro fertilization treatment procedures can thus be made simpler by the transfer of embryos at the pronucleate stage.

Adult↗